Intro to Psychology - Y3B2 PDF

Week 1 session 1: Methods of Psychology (ch2) § Psychology as the science of behavior and the mind § Science: attmept to answer questions through the systematic collection and analysis of objecive, publicly observable data § Science of psychology: observe and explain behavior o Once the results of a scientiﬁc experiment are collected and analyzed, they need to be explained in natural cause-and-eBect terms o In psychology: data are measures or descriptions of some form of human or animal behav ior o Challenges exist in choosing what data to collect, collecting the data, and drawing conclusions from them. § Lessons from clever hans o Clever hans: horse o Pfungst: psychologist o The mystery: the horse could answer questions to many disciplines in many languages o The solution: psychologist Oskar Pfungst performed a few simple experiments § Pfungst theorized that Hans answered questions through responding to visual signals inadvertently produced by the questioner or other observers. § Signals: Immediately after asking a question that demanded a hoof-tap answer, the questioner and other observers would naturally move their heads down just a bit to observe the horse’s hoof. This, it turned out, was the signal for Hans to start tapping. To determine whether Hans would be correct or not, the questioner and other observers would then count the taps and, unintentionally, make another response as soon as the correct number had been reached. This response varied from person to person, but a common component was a slight upward movement of either the whole head or some facial feature, such as the eyebrows. § Hans’s yes–no headshake responses were also controlled by visual signals. Questioners and observers would unconsciously produce slight up-and-down head movements when they expected the horse to answer yes and slight back-and-forth head movements when they expected him to answer no, and Hans would shake his head accordingly § Observations, theories, and hypotheses o Observation: objective statement that reasonable observers agree is true § In psychology: usually particular behaviors, or reliable patterns of behaviors, of people or animals o Theory: an idea, or a conceptual model, designed to explain existing observation and make predictions about new observations that might be discovered o Hypothesis: prediction about new observation made from a theory o Cycle of science: Observations lead to theories, which lead to hypotheses, which are tested with experiments or other research studies; these in turn lead to new observations, which sometimes lead to new theories, etc § Theory without observations is merely speculation, and observations without theory are simply data without explanations. § The lessons o 3 lessons about scientiﬁc reseaarch in the story § Value of skepticism Critical thinking (using knowledge of the world to develop alternative perspectives and then develop tests to evaluate them ) Parsimony or Occam’s razor o the more extraordinary a claim is—the more it deviates from accepted scientiﬁc principles—the stronger the evidence for the new theory needs to be. To suggest a complex, extraordinary explanation of some behavior requires that all simple and conventional explanations be considered ﬁrst and judged inadequate o The simpler the explanation, the better it tends to be o Principle of parsimony = when there are two or more explanations that are equally able to account for a phenomenon, the simplest is usually preferred § Value of careful observations under controlled conditions Identifying the conditions certain behaviors are contingent upon § The problem of observer-expectancy eBects In studies o fhumans and other sentient animals the observers may unintentionally communicate to subjects their expectations about how they “should’’ behave, and the subjects, intentionally or not, may respond by doing just what the researchers expect. § Types of research strategies o 3 dimensions of research strategies: § Research design: experiments, correlational studies, and descriptive studies § Setting: ﬁeld and laboratory § Data-collection method: self-report and observation o Research designs § To test a hypothesis, choosing the design that best ﬁts the conditions they want to control § Experiments Molst direct and conclusive approach testing a hypothesis about a cause–eBect relationship between two variables (= anything that c an channge or assume diBerent values). Independent variable: hypothesized to cause some eBect on another variable Dependent variable: the variable aBected o In psychology: ususally measures of behavior Experiment = a procedure in which a researcher systematically manipulates one or more independent variables and looks for chnages in one or more dependent variables whil keeping all other variables constant o Causation can be assumed due to ceteris paribus Subjects/Participants of the experiment: o within-subject /repeated-measures experiments: each subject is tested in each of the diBerent conditions of the independent variable o between-groups/between-subjects experiments: there is a separate group of subjects for each diBerent condition of the independent variable. § Here random assignment of participants into treatment groups to avoid bias § Correlational studies Impossibility of experiments due to practical or ethical reasons -› so instead correlational study o = the researcher does nit manipulate any varaible, but observes or measures two or more already existing dependent varaibles to ﬁnd relationships between them o can identify relationships between variables -› make predictions about one variable based on knowledge of another -› but do not tell us whether change in one variable is the cause of change in another. Cause and eBect cannot be determined here as: o The researcher didn’t control any variable o The causal relationship may go in both directions o Or there might have been a confounding third variable aBecting both that we didn’t account for § Leads to spurious correlations o Correlation doesn’t imply causality Analysis of correlational studies often: one variable used to place subjects into separate groups and the groups are compared on the other variable o Or both variables measured numerically and see their correlation (e.g height and popularity) § Here data assessed by correlation coeBicient statistic § Descriptive studies = describing the behavior of an individual or set of individuals without assessing relationships between diBerent variables o E.g. prevalence of a mental disorder within a population -› numerical descriptive o Or courtship behavior of animals –› non-numerical o Research settings: § Laboratory study: subjects are brought to a specially designated area that has been set up to facilitate the researcher’s collection of data or control over environmental conditions Data collection. Under more uniform, controlled conditions -› but als artiﬁcial setting may induce behaviors that obscure to-be-studied behavior o Strange environment and awareness of being ob served More for experimetns § Field study: research study conducted in a setting where the researcher does not have control over the subjects’ experiences. In subject’s natural environment More for correlational and descriptive studies § Combined lab and ﬁeld studies to counteract some of the problems o Data collection methods: § Self-report methods: people are asked to rate or describe their own behavior or mental state Through questionnaires or brief esssay questions o Validity of this data is limited by subjects’ ability to observe and remember their own behavior or moods o + wilingness to respond and report on these frankly Or through intrviews o Tightly or loosely structured interview One form of self-report is introspection (=personal observations of one’s thoughts, perceptions, and feelings) o Used in modern psychology (Wilhelm Wundt) o Modern methods for measuring neural activity are able to correlate people’s introspections with what’s happening in the brain, providing more objective, “observable behavior” § Observatgional methods: all procedures by which researchers observe and record the behavior of interest One subcategory: tests o Researcher delibertaely presents a problem, task or situation to ehich subjects respond o easily scored but are by nature artiﬁcial, and their relevance to everyday behavior is not always clear Another: naturalistic observation: researcher doesn’t interfere with the subjects’ behavior o But one caution: subjects know that they are being watched -› Hawthorne eBect (= changes in subjects’ behavior as a result of knowing they are being watched) o To minimize Hawthorne eBect: § Habituation: a decline in response when a stimulus is repreatedly or continuously present over time, subjects may habituate to the presence of the researcher and go about their daily activities more naturally than they would if suddenly placed under observation. o They also take great amount of time § + diBiculty of observing ongoing behavior without interfering with it § diBiculty of coding results in a form that can be used for statistical analysis. § Statistical methods in psychology o 1) descriptive statistics: used to summarize sets of data § All numrical methods for summarizing a set of data § Mean, median and measure of variability § Decribing a set of scores: Mean: arithmetic avergae Median: center score o determined by arranging the scores from highest to lowest and ﬁnding the score that has the same number of scores above it as below it, that is, the score representing the 50th percentile. Not only central tendency but also variability of a set of nmbers o Variability = the degree to which numbers in the set diBer from one another and from the mean o Comon measure: standard deviation § Calculated by a formula -› the farther most individual scores are from the mean, the greater is the standard deviation. § Describing a correlation: examine two or more variables to determine whether or not a nonrandom relationship exists between them When both variables are measured numerically -› strength and direction of relationship can be assessed by the correlation coe+icient. o calculated by a formula that produces a result ranging from –1.00 to +1.00. o positive correlation, an increase in one variable coincides with a tendency for the other variable to increase o a negative correlation, an increase in one variable coincides with a tendency for the other variable to decrease. absolute value of the correlation coeBicient indicates the strength of the correlation. o To the degree that a correlation is strong (close to +1.00 or –1.00), you can predict the value of one variable by knowing the other. o A correlation close to zero (0) means that the two variables are statistically unrelated, that is, knowing the value of one variable does not help you predict the value of the other. o Moderate and sotrong correltaions o 2) inferential statistics: helps deciding how conﬁdent researchers can be in judging whether results observed are due to chance § Necessary due to the degree of variability that can be attributed to chnace § Answering general conclusions with the laws of probability § Statistical signiﬁcance: Inferential statistical methods, applied to either an experiment or a correlational study, are procedures for calculating the probability that the observed results could derive from chance alon Calculating the p statistics = level of signiﬁcance o When two means are being compared, the p value is the probability that a diBerence as great as or greater than that observed would occur by chance if, in the larger population, there were no diBerence between the two means. o p value is the probability that a diBerence as large as or larger than that observed would occur if the independent variable had no real eBect on the scores. o In the case of a correlational study, p is the probability that a correlation coeBicient as large as or larger than that observed (in absolute value) would occur by chance if, in the larger population, the two variables were truly uncorrelated o results are usually labeled as statistically signiﬁcant if the p value is less than.05 (5%). § To say that results are statistically signiﬁcant is to say that the probability is acceptably small (generally less than 5%) that they could be caused by chance alone § The components of a test of statistical signiﬁcance Size of observed eBect o Large eBect more likely to be signiﬁcant than a small one Number of individual subjects or observations in the study o Results are more likely to be signiﬁcant the more subjects or observations included o larger the sample is, the more accurately an observed mean (or correlation coeBicient) reﬂects the true mean (or correlation coeBicient) of the population o If the number of subjects or observations is huge, even very small eBects is statistically signiﬁcant, that is, reﬂect a “true” diBerence in the population Variability of the data within each group o Variability can be described as an index of the degree to which uncontrolled, chance factors inﬂuence the scores in a set of data o the less the variability is within each group, the more likely the results are to be signiﬁcant. § But statistical signiﬁcance is not practical signiﬁcance § Minimizing bias in Psyc hological research o Bias = nonrandom (directed) eBects caused by some factors extraneous to the research hypothesis § Statistical techniques cannot identify or correct for bias § error only reduces the chance that researchers will ﬁnd statistically signiﬁcant results (by increasing the variability of the data), bias can lead researchers to the false conclusion that their hypothesis has been supported when some factor irrelevant to the hypothesis caused the observed results o avioding biased samples: § group is a biased sample if: the members of a particular group are initially diBerent from those of another group in some systematic way, o Counteract it with random assignment of participants -› then individual diBerences are mainly a source of error and not bias Members are diBerent from the larger population that the researcher is interested in o Problem of human subjects who are easily available to be studied may not be representative of the greater population o most psychological research is drawn from samples from Western, Educated, Industrialized, Rich, and Democratic (WEIRD) societies, and that this greatly limits what we can say about any universal characteristics we may uncover. o Reliability and validity of measurements § Reliability: has to do with measurement error measure is reliable to the degree that it yields similar results each time it is used with a particular subject under a particular set of conditions, sometimes referred to as replicability. o low reliability decreases the chance of ﬁnding statistical signiﬁcance Second type of reliability is interobseved reliability: the same bhavior seen by one observer is also seen by a second ovserber o Requires careful deﬁnition of behavior priorly -› operational deﬁnition to deﬁne the dependent measure § deﬁnes something in terms of the identiﬁable and repeatable procedures, or operations, by which it can be observed and measured § Validity: Lack of validity can be a source of bias measurement procedure is valid if it measures or predicts what it is intended to measure or predict for example, suppose we decided to assess personality in adults by measuring thumb length. This procedure is highly reliable (we would get nearly the same thumb length score for a given person each time) but almost certainly not valid (thumb length is almost assuredly unrelated to personality) If the measurement procedure appears to assess the variable that it is supposed to measure, we say the procedure has face validity more certain way to gauge validity -› correlate its scores with another, more direct index of the characteristic that we wish to measure or predict. o more direct index is called the criterion o validity is called criterion validity. requires a clear operational deﬁnition of the characteristic to be measured or predicted o avoiding observer-expectancy and subject-expectancy eBects § form of bias from expectations of the experimenters –› observer- expectancy eBects § researcher who wants or expects a subject to respond in a particular way may unintentionally communicate that expectation and thereby inﬂuence the subject’s behavior. Like the case of clever hans Avoiding observer-expectancy eBects in typical experiments o To keep observer blind (uninformed) about those aspects of the study’s design that could lead him or her to form potentially biasing expectations. § a blind observer would not be told which subjects received which treatment Avoiding subject-expectancy eBects o Blindness about the treatment o Double-blind experiment: in which both observer and subject are kept blind o Replicating earlier studies § Replicability with respect to reliability: A measure is reliable/replicable to the degree that it yields similar results each time it is used with a particular subject under particular conditions § Recent research has shown that many ﬁndings published in prominent psychology journals do not replicate, although most replication studies produced the same pattern as the original studies. § Science is a conservative institution, and textbook writers in particular are likely to include only well-established ﬁndings. § Ethical issues in Psychological research o Research with humans § Informed consent before participating Informed about what the study is about, and potential risks § Person’s right ot privacy not have to share any information about themselves that they do not wish to share keeping reports and records in ways that ensure anonymity. § The possibility of discomfort or harm Participants must be free to quit § The use of deception Can be resolved by posterior debrieﬁng § Special considerations for children, limited intellectual capacity, limited DM capacities (e.g. prisoners) o Research with animlas § ethical obligation to balance the animals’ suBering against the potential beneﬁts of the research. § Animals must be well cared for and not subjected to unnecessary deprivation or pain o Formal principles and safeguars for ethical research § Establishment of ethics review panels in some countries -› Institutional Review Boards (IRBs) Week 1 session 2: neural Coding of Behavior (ch4) – look at notes in summary pdf § Neurons: the building blocks of the brain o Brain: most complex and compact computing machine in the universe § Consumer 20% of metabolic energy § o Contains 86 billion nerve cells or neurons § Unlike other cells -› neurons are not compressed but separated but communicate with each other Through connections called synapses (100 trillion) Neurons are constantly active, and their collective activity monitors our internal and external environments, creates all of our mental experiences, and controls all of our behavior. § Each neuron in itself is a compex Dming machine o Three basic varieties of neurons and structure common § Layout of the human nervous system: § Central nervous system: brain and spinal cord Integrates and synthesizes neural info § Peripheral nervous system: nerves Relays info to and from the brain from other parts of the body § Neuron vs nerve Neuron: single cell of the nervous system Nerve. Bundle of many neurons o Or a bundle consisting of the axons of many neurons within the peripheral nervous system o Nerves connect the central nervous system to the body’s sensory organs, muscles, and glands. § central and peripheral nervous systems are not two separate systems, but are parts of an integrated whole § 3 diBerenrt categories of neurons according to their functions and their locations in the overall layout of the nervous system: Sensory neurons: o bundledtogethertoformnerves,carryinformation from sensory organs (including the eyes, ears, nose, tongue, and skin) into the central nervous system Motor neurons: o Also bundled into nerves, carry messages out from the central nervous system to operate muscles and glands. Interneurons: o Exist entirely within the central nervous system and carry messages from one set of neurons to another. Interneurons collect, organize, and integrate messages from various sources. They vastly outnumber the other two types. o interneurons make sense of the input that comes from sensory neurons, generate all our mental experiences, and initiate and coordinate all our behavioral actions through their connections to motor neurons. § § Parts of neurons: cell body :widest part of the neuron o contains the cell nucleus and other basic machinery common to all bodily cells. Dendrites: thin, tubelike extensions that branch extensively and function to receive input to the neuron. o In motor neurons and interneurons dendrites extend directly oB the cell body and generally branch out from it, forming bushlike structures. § increase the surface area of the cell and thereby allow for receipt of signals from many other neurons. o In sensory neurons, dendrites branch out from one end of the axon, rather than directly from the cell body. T § extend into a sensory organ and respond to sensory signals, such as sound waves in the ear or touch on the skin Axon: thin, tubelike extension from the cell body. o Its function is to carry messages to other neurons or, in the case of motor neurons, to muscle cells. o microscopically thin, but some extremely long. o Most axons form many branches some distance away from the cell body, and each branch ends with a small swelling called an axon terminal. § designed to release chemical transmitter molecules onto other neurons or, in the case of motor neurons, onto muscle cells or glandular cells. o The axons of some neurons are surrounded by a casing called a myelin sheath. Myelin is a fatty substance produced by supportive brain cells called glial cells. § helps to speed up the movement of neural impulses along the axon. Motor neuron: o How neurons send messages along their axons § Exerting inﬂuence on other neurons or muscle cells by ﬁring oB all- or-none impulses called action potentials § Motor and interneurons: action potential triggeed at the junction between cell body and axon -› travel down rapidly to axon terminals § Sensory neurons: triggered at the dendritic end of the axon and travel past the cell body to the axon terminals § All-or-non: action potentials either occur or don’t -› they don’t occur partially or in diBerent sizes or gradations Action potentials produced by the same neurons are the same strentgth + each retains its full strength all the way down to the axon each action potential is all or none but a neuron can convey varying degrees of intensity in its message by varying its rate of producing action potentials. o rate anywhere from less than 1 per second to as many as 1,000 per second. o By varying its rate of action potentials, a neuron varies the strength of its eBect on other neurons or muscle cells. o The resting neuron has a constant electrical charge across its membrane § Cell membrane enclosing each neuron = porous skin permiting certain chemical to ﬂow into and out of the cell, while blocking others Solution of water and dissolved chemicals (= intercellular ﬂuid) o On the outside: another solution of water and dissolved chemicals of extracellular ﬂuid Some of these chemicals dissolved with electrical charges o soluble protein molecules (A−), which have negative charges and exist only in the intracellular ﬂuid; o potassium ions (K+), which are more concentrated in the intracellular than the extracellular ﬂuid o sodium ions (Na+) and chloride ions (Cl−), which are more concentrated in the extracellular than the intracellular ﬂuid. o more negatively charged particles exist inside the cell than outside. § imbalance results in an electrical charge across the membrane, with the inside typically about −70 millivolts relative to the outside. § charge across the membrane of an inactive neuron = resting potential the source of electrical energy that makes an action potential possible. § o The action potential is elicited by a brief change in membrane permeability § action potential is a wave of change in the electrical charge across the axon membrane § moves rapidly from one end of the axon to the other § Its electrical recording over time: § Action(about 1 milisecond) potential initiated by a change in the structure of the cell membrane at one end of the axon Sodium channels open up -› sodium ﬂows into the cell -› reverse electricaé charge across the membrane (positive inside momentarily) o -› depolarization phase Then sodium channels close, but potassium channels remian open -› they are pushed outwards o Reestablisihing initail resting potential -› repolarization phase To maintain the original balance of these ions across the membrane, each portion of the membrane contains a chemical mechanism, the sodium-potassium pump, that continuously moves sodium out of the cell and potassium into it § The action potential regenerates itself from point to point along the axon Action potentials triggered at one end of an axon by inﬂuences reducing the electrical charge across the cell membrane. o Sensory neurons inﬂuenced by sensory stimuli acting on the dendrites o motor neurons inﬂuenced by other neurons acting on the axon at its junction with the cell body. axon’s membrane’s sodium channels open in response to depolarization (reduction in charge across the membrane) to some critical value. o called the cell’s threshold -›triggers an action potential Once an action potential occurs at one location on the axon, it depolarizes the area of the axon just ahead of where it is occurring, thus triggering the sodium channels to open there. o action potential keeps renewing itself and moves continuously along the axon. When an axon branches, the action potential follows each branch and thus reaches each of the possibly thousands of axon terminals. Speed aBected by the axon’s diameter o Large-diameter axons conduct action potetials faster + also the myelin sheath -› protects and insulates axons -› speeds the rate of nervous impulses o Process of developing myelin (=myelination) begins before birth but uncomplete until adulthood o Neurosn in the sensory system are ﬁrst to be myelinated (before age 1) -› then of the motor area (before age 2) -› and lastly the associative areas in the frontal cortex (thinking area of brain)(in adulthood) o How neurons inﬂuence other neurons: synaptic transmission § Rate of action potential inﬂuenced by all the info sent to them from other neurons § Synapse: juntion between each axon terminal and the cell body or dendrite if the receiving neuron § When action potential reaches action terminal -› causes terminal to release chemical substance = neurotransmitter (includes dopamine, acetylcholine, GABA (gamma-aminobutyric acid), and serotonin, etc) Moves across intercell space Alters the adjacent, receiving neuron to inﬂuence its production of action potentials -› increasing or decreasing (inhibiting) the likelihood that a neuron will ﬁre Finctions of diBerent neurotransmotters: § best-understood synapses: between axon terminals and muscle cells or between axon terminals and the dendrites of other neurons § narrow gap, = synaptic cleft, separates the axon terminal from the membrane of the cell that it inﬂuences. § presynaptic membrane: membrane of the axon terminal that abuts the cleft § postsynaptic membrane: that of the cell on the other side of the cleft § Within the axon terminal -› tiny globe-like vesicles -›each contains several thousand molecules of a chemical neurotransmitter. § § some of the neurotransmitter molecules diBuse across the cleft and bind at special receptors on the postsynaptic membrane, where they open channels that permit ions to ﬂow through the membrane. § If the postsynaptic cell is muscle cell-› ﬂow of ions triggers a biochemical process that causes cell to contract § If is a neuron, -› change in the polarization of that neuron -› direction of change depends on whether synapse is excitatory or inhibitory excitatory synapse: channels permeable to sodium ions (Na+) open, allowing an inﬂux of positive charges into the receiving neuron o depolarization and increase in the rate of action potentials triggered inhibitory synapse: channels permeable to chloride ions (Cl–)or potassium (K+) open -› movement of negatively charged Cl- into the cell or of positively charged K+ out of the cell causes slight hyperpolarization of the receiving neuron (becomes even more negative inside than it was before). o Hyperpolarization tends to decrease the rate of action potentials. § Postsynaptic neurons integrate their excitatory and inhibitory inputs Many simoultaneous exitatory and inhibitors inputs -› spread passively through the dendrites and cell body -› integrated eBect on the electrical charge across the membrane of the axon at its junstion with the cell body whenever axon membrane depolarized below critical value, -› action potentials triggered o greater the degree of depolarization below that value, the greater the number of action potentials per second. rate of action potentials in the postsynaptic neuron’s axon depends on the net eBect of the depolarizing and hyperpolarizing inﬂuences from excitatory and inhibitory synapses. o The development of neurons § Newborns have more neurons in their brains than adults § Neurogenesis = process of creating new neurons During the ﬁrst 20 weeks after conception -› continues after birth well into adulthood, particularly in the hippocampus, an area involved in memory After “birth” neurons migrate to their permament location in the brain Last stage of development = diBerentiation o neurons grow in size and increase their numbers of dendrites and axon terminals + the number of synapses they form -› doesn’t stop at birth. o Synapse formation is most rapid in the months immediately following birth, but the peak of synapse formation varies for diBerent parts of the brain § Cell death and synaptic pruning After birth -› loss of neurons o Although brains do grow larger with age, this increase is due primarily to the increasing size of individual neurons and myelination of axons, not to the generation of new neurons o Number of neurons and synapses decreases after early developmnt Selective cell death/ apoptosis = death of neurons Synaptic pruning = loss of synapses They occur at diBerent rates in diBerent brain parts Brain development as a metaphor of sculpting o First overproduction of neurons and synapses o Then chiseling down o Mirror neurons: a means of social learning? § Mirror neurons: Organized systems of neurons that seem to be well designed for social learning Help to mimic what we observe and experience Found in various parts of the cerecral cortex of monkey and humans active both when a subject engages in a behavior and when the subject observes someone else perform a similar action. -› basis for imitation more generally they refelct an individual being able to recognize when another is doing something the self can do o in monkeys Transcranial Magnetic Stimulation (TMS) and functional magentic resonance imaging (fMRI) allows for the observation of mirror neurons in humans o Mirror neurons in humans: § They code for movements forming an action not only for action itself (unlike monkeys) Impritance in imitative learning § Some believe mirror neurons represent a brain- based mechanism for identifying with others -› basis of imitative learning, speech perception, empathy, and even language § Understanding others’ intentions is the foundation for advanced forms of social cognition § Methods for mapping the brain’s behavioral Functions o Methods used for studying the human brain § 3 general categories 1) observing behavioral deﬁcits that occur when a part of the brain is destroyed or is temporarily inactivated (2) observing behavioral eBects of artiﬁcially stimulating speciﬁc parts of the brain (3) recording changes in neural activity that occur in speciﬁc parts of the brain when a person or animal is engaged in a particular mental or behavioral task. § observing eBects of localised brain damage: By studying people who have damage in the same general area of the brain -› draw reasonable inferences about the behavioral and mental functions of that area. Logic: if some abilities are missing and other abilities remain when a part of the brain is missing, then that brain part must contribute in some essential way to the missing abilities but not to those that remain Caution: brain damage can rarely be narrowed to one area o frequently involves complications beyond that of simple lesions, or areas of speciﬁc damage o Lesions in one area of the brain can also lead to changes in other brain areas § Observing eBects of magnetic interference with normal brain activity Transcranial magnetic stimulation (TMS): o Pulse of electricity sent through small copper coil -› magnetic ﬁeld around coil -› held above a person’s scalp to induce electric current in the neurons immediately below the coil o Repetitive pulses cause a temporary loss in those neurons’ abilities to ﬁre normally -› eBect comparable to that of lesioning a small area of the brain, with the advantage that the eBect is temporary and reversible. o Can be used for mapping functions only of the outermost, yet largest part of the brain (cerebral cortex) o TMS is usually used to study the eBects of temporary inactivation of a brain area § But can also be used to study the eBects of temporary activation o TMS can be used to produce a map of the functional connections between speciﬁc areas within movement-control portions of the cerebral cortex and the muscles controlled by those areas. similar technique: transcranial direct current stimulation (tDCS): directing weak electrical currents to speciﬁc areas of the brain o alters perceptual, cognitive, and motor functioning. o Also eBective in alleviating some brain disorders § Recording brain activity electrically, through the scalp constant activity of brain’s billions of neurons produces continuous electrical “chatter,” which to some degree penetrates the skull and scalp. placing electrodes on a person’s scalp-› detect and amplify these signals. resulting record of brain activity = electroencephalogram (EEG) o Patterns in EEG can be used as an index of whether a person is highly aroused, or relaxed, or asleep and can be used to identify various stages of sleep. brief change in EEG record immediately following the stimulus = event- related potential (ERP) o Comparison of average ERPs recorded at diBerent scalp locations reveals pattern of brain activity as the person detects and responds to the stimulus § Viewing brain activity with imaging methods sensitive to blood ﬂow Some methods rely on: increased neural activity in a brain area is accompanied by increased blood ﬂow to that area o Blood carries oxygen and glucose -› sources of energy required to sustain increased neural activity o Creating 3D neuroimages depicting the amount of blood ﬂowing through each part of the brain Positron emission tomography (PET) o Injecting a radioactive substance into the blood + measuring the radioactivity that is emitted from each portion of the brain Functional magnetic resonance imaging (fMRI) o creation of a magnetic ﬁeld around a person’s head, causing hemoglobin molecules that are carrying oxygen in the blood to give oB radio waves of a certain frequency; o waves can be detected and used to assess the amount of blood in each part of the brain. o Unlike the EEG, PET and fMRI can depict activity anywhere in the brain, not just on the surface near the skull. § +produce a more ﬁne-grained picture of the spatial locations of activity § fMRI is used much more often than PET, partly because it shows better spatial resolution. o But need for appropriate control conditions for accurate data and conclusions § subtracting the amount of activity measured in each brain area in the control condition (when the person is not performing the speciﬁc task) from the amount measured in the same areas in the experimental condition (when the person is performing the task) -› determine which areas show the greatest increase in activity during the task o These studies must be accompanied by behavioral assessment and experimental studies o Methods used for studying brains of nonhuman animals § Observing eBects of deliberately placed brain lesions Lesions = areas of damage o Produced in animals’ brains byelectrically or chemically destroying neurons o To identify precise brain areas that are crucial for speciﬁc types of behaviors § EBects of stimulating speciﬁc areas of the brain Electrically or chemically o Electrical shock: strong enough to induce action potentials in, but not destroy, neurons near the electrode tip o Chemically: tiny amount of a neurotransmitter substance or other chemical known to activate neurons is injected o stimulation in certain deep areas of the brain can cause an animal to exhibit drive states or emotional states that last only as long as the period of stimulation. § Electrical recording from single neurons Electrodes to record neural activity in speciﬁc areas as the animal engages in behavioral tasks Place cells: help animals keep track of direction they are facing within familiar environments § Functional organization of the nervous system o Nervous system hierarchically organized § Two distinct but interacting hierarchies 1) sensory-perceptual hierarchy o Involved in data processing o receives sensory data about a person’s internal and external environment, and it analyzes those data to make decisions about the person’s bodily needs and about threats and opportunities in the outside world. o ﬂow of information: primarily from bottom (sensory receptors) to top (perceptual centers in the brain) 2) motor-control hierarchy o Control of movement o Flow of info primarily from top (executive centers making decisions about activities to engage in) to bottom (centers that translate those decisions into speciﬁc patterns of muscle movement) § Bottom parts of the hierarchy are evolutionarily the most primitive and are most directly tied to the muscles and the sensory organs. o Peripheral nerves: the nervous system’s interface with the world § Peripheral nervous system: Entire set of nerves connecting the entral nervous system to the body’s sensory organs, muscles, and glands Nerves divided in 2 classes corresponding to the portion of the central nervous system from which they protrude: o Cranial nerves: project directly from the brain o Spinal nerves projects from the spinal chord Nerves exits in pairs -› right and left member o 12 pairs of cranial nerves and 31 pairs of spinal nerves § Sensory neurons provide data needed for governing behavior sensory neurons are activated at their dendritic ends by the eBects of sensory stimuli send action potential into the central nervous system through their long axons o rates and patterns of action potentials in sensory neurons = data that perceptual areas of the central nervous system use to ﬁgure out the state of the external and internal environment o sensory input from sensory organs on the head -› enter the brain through cranial nerves o sensory input from rest of the body -› enters central nervous system through both cranial and spinal nerves somatosensation= sensations conveyed ny these inputs (e.g. touch, pain) o = set of sensations that derive from the whole body as opposed to those that come just from the special sensory organs of the head. § Motor neurons are the “ﬁnal common path” for control of behavior Motor neurons with cell bodies inside the central nervous system o send their long axons out through cranial or spinal nerves, to terminate on muscles or glands. o behavioral decisions of the nervous system are translated into patterns of action potentials in the axons of motor neurons -› determine our behavior. § The motor system includes somatic and autonomic divisions Motor neurons act on two broad classes of structures: o Skeletal muscles attached to bones and produce externally observable movements of the body when contracted. § Neurons that act on skeletal muscles = somatic (body) portion of the peripheral motor system § They initiate activity -› skeletal muscles inactive in absence of neural input o visceral muscles and glands § Visceral muscles form the walls of the heart, arteries, stomach, intestines § Glands: produce secretions (saliva and sweat) § Neurons here make up the autonomic portion of peripheral motor system Visceral muscles have built-in, nonneural mechansism for generating activity Most visceral muscles and glands receive two sets of neurons producing opposite eBects and come from two anatomically distinct divisions of the autonomic system: sympathetic and parasympathetic sympathetic: responds to stressful stimulation, preparing for ﬂight or ﬁght o EBects: § Increased heart rate and blood pressure § Release of energy molecules (sugars and fats) from storage deposits to permit high energy expenditure § Increased blood ﬂow to skeletal muscles § Inhibition of digestive processes Parasympathetic division: regenerative, growth-promoting, and energy-conserving functions through eBects that include the opposites of those just listed for the sympathetic division. § The modulate (modify) rather than initiate activity o The spinal chord: a conduit and an organizer if simple behaviors § The spinal cord contains pathways to and from the brain Asceding tracks: carry somatosensory information brought in by the spinal nerves up to the brain descending tracts: carry motor control commands down from the brain to be transmitted out by spinal nerves to muscles § the spinal chord organizes simple reﬂexes some reﬂexive behaviors do not require the brain; they are organized by the spinal cord alone ﬂexion reﬂex: involves the contraction of ﬂexor muscles that bend the limb at each joint, causing it to be pulled inward (ﬂexed) toward the body adaptive advantage of the ﬂexion reﬂex: quickly and automatically moves the limb away from potentially damaging stimuli o occurs quickly as it occurs at the level of the spinal cord and does not require that messages be sent up to the brain for further processing and then be sent back down again. § The spinal cord contains pattern generators for locomotion spinal cord is capable of generating sustained, organized movements without the involvement of the brain -› chicken with head cut oB spinal cord contains networks of neurons (=pattern generators) that stimulate one another in a cyclic manner -› produce bursts of action potentials that wax and wane in regular, repeating rhythm Pattern generators activate motor neurons in the spinal cord to produce the rhythmic sequence of muscle movements that results in walking, running, ﬂying, swimming Normally, pattern generators controlled by neurons descending from the brain -› can be either inhibited, ( motionless animal) or activated to varying degrees, producing varying rates of locomotion. o Subcortical structures of the brain § Lower more primitive parts of the brain = subcortical structures Due to position beneath the cerebral cortex (topmost part of brain) § The brainstem organizes species-typical behavioral patterns The spinal cord enlarges and becomes the brainstem as it enters the head o Parts of brainstem (from bottom up): § Medulla § Pons § Midbrain brainstem functionally and anatomically similar to the spinal cord, but more elaborate. spinal cord: site of entry of spinal nerves brainstem is the site of entry of most (10 of the 12 pairs) of the cranial nerves. Both spinal cord and brainstem contain ascending (sensory) and descending (motor) tracts that communicate between nerves and higher parts of the brain. like the spinal cord, brainstem has some neural centers that organize reﬂexes and species-typical behavior patterns Medullas and pons: organize reﬂexes that are more complex and sustained than spinal reﬂexes o Postural reﬂexes (help maintain balance while standing or moving) o Vital reﬂexes (regulate breathing rate, heart rate) Midbrain: neural centers that govern species-typical movement patterns (eating, drinking, attacking) o + neurons that act on pattern generators in the spinal cord to increase or decrease the spped of locomotion o midbrain and structures below it contain neural systems that organize species-typical patterns of movement but do not contain neural systems that permit deliberate decisions to move or refrain from moving in accordance with the animal’s long-term interests or needs. § The cerebellum and the basal ganglia help to coordinate skilled movements Cerebellum: little brain Basal ganglia: set of interconnected structures on each side of the thalamus Damage to either can greatly interfere with a person’s ability to produce learned, skilled, well-coordinated movements o Damage to cerebellum: loss of ability to rapid, well- timed sequences of muscle movements, such as pitching a baseball, leaping over a hurdle, playing a musical instrument, or typing a series of words at a computer o Damage to basal ganglia: oss of ability to coordinate slower, deliberate movements, such as reaching out to pick up an object § Both structures use sensory info to quide movements o Basal ganglis uses sensory info in a feedback manner -› sensory input pertaining to an ongoing movement (such as the sight of how the hand is moving) feeds back into the basal ganglia and is used to adjust the movement as it progresses. o Cerebellum uses sensory information primarily in a feed- forward manner –› uses sensory info to program appropriate force and timing of a movement before it is initiated -›crucial for movements that occur too rapidly to be modiﬁed once they are in progress. § The thalamus is a relay station for sensory, motor, and arousal pathways Thalamus as a relay station that connects various parts of the brain with one another. Most of the sensory tracts that ascend through the brainstem terminate in special nuclei in the thalamus; those nuclei, send their output to speciﬁc areas in the cerebral cortex. o also nuclei that relay messages from higher parts of the brain to movement- control centers in the brainstem. Role in the arousal of the brain as a whole o Arousal pathways in the midbrain converge in the center of thalamus and project diBusely to all areas of the cerebral cortex. § The limbic system and the hypothalamus play essential roles in motivation and emotion § Limbic system: as the border dividing the evolutionarily older parts of the brain below it from the newest part (the cerebral cortex), above it. o consists of several distinct structures that interconnect with one another in a circuit wrapped around the thalamus and basal ganglia o Some of these structures especially the amygdala involved in regulation of basic drives and emotions o hippocampus: keeping track of spatial location (direction-sensitive place cells located here) + encoding certain kinds of memories o strong connection to the nose and sense of smell -› can invoke drive, emotions, and memories o limbic system receives input from all other sensory organs § connected to the basal ganglia -› helps translate emotions and drives into actions hypothalamus: o connected to all structures of the limbic system o primary task: regulate the internal environment of the body by § (a) inﬂuencing the activity of the autonomic nervous system § (b) controlling the release of certain hormones § (c) aBecting certain drive states, such as hunger and thirst. § through its connections with the limbic system, it helps to regulate emotional states, such as fear and anger. o Major role in regulating basic drives of survival § Fighting, ﬂeeing, feeding, fornicating o The cerebral cortex § Evolutionary newest and outermost and largest part of brain § Divided into left and right hemispheres Each hemisphere divided into 4 lobes demarcated by prominent inwardly folding creases or ﬁssures Lobes from back to front: o Occipital o Temporal o Parietal o Frontal lobes o § The cortex includes sensory, motor, and association areas 3 categories of functional regions o 1) Primary sensory areas: receive signals from sensory nerves and tracts by way of relay nuclei in the thalamus § include the visual area in the occipital lobe, the auditory area in the temporal lobe, and the somatosensory area in the parietal lobe. o 2) primary motor area: sends axons down to motor neurons in the brainstem and spinal cord § At the rear of the frontal lobe o 3) association areas § All remaining parts of the cortex § Receive inputs from the sensory areas and lower parts of the brain § Invlved in complex processes of perception, thought, and decision making § The primary sensory and motor areas are topographically orgnaized Principle of topographic orgnaization: primary sensory and motor areas are organized in such a way that adjacent neurons receive signals from or send signals to adjacent portions of the sensory or muscular tissue to which they are ultimately connected o Eg neurons that are near one another in the visual cortex receive signals from receptor cells that are near one another in the retina of the eye o amount of cortex devoted to each part of the body corresponds not to the size but to the degree of sensitivity of that part (in the case of the sensory map) or the ﬁneness of its movements (in the case of the motor map) § Huge areas devoted to controlling ﬁngers and vocal apparatus (ﬁne control) Premotor areas: o in front of the primary motor areas o Devoted to motor control -› neural programs for producing organized movements or patterns of movement based on info sent from the anterior (forward) portion of the frontal lobe involved in overall behavioral planning o executing an action program: send info out tocerebellum, basal ganglia, and motor cortex to reﬁne the program further before sending messages down toward the muscles § § Prefrontal association areas create general plans for action Prefrontal cortex: o Most advanced in humans o Involved in executive function = processes involved in regulating attention and in determining what to do with info gathered or retrieved from long-term memory o Central role in planning and behaving ﬂexibly § Especially when dealing with new info o General ﬂow of info in the cortex for control of movements (pic above): § Association areas in the rear of the cortex, especially in parietal and temporal lobes, analyze info that comes to them from sensory areas. § then send output to prefrontal association areas, which also receive info about the internal environment through strong connections with the limbic system § combining all info -› preforntal areas set general plans for action § plans put into eBects through connections to motor cortex and downward links to the basal ganglia and cerebellum § hierarchical orgnaization in the control of movement: a summary review of movement-control functions o Structures organized according to their general roles in controlling movement, not according to anatomical positions. § highest structures involved in motivation and planning, § lower structures involved in reﬁning and executing plans, turning them into action. § both subcortical and cortical structures involved at each of the top three levels in the hierarchy. § §Word of caution: knowledge that certain parts of the brain are essential for certain aspects of behavioral control can be mistaken for knowledge about how those processes are accomplished. The discovery of “where” does not explain “how § How hormones interact with the nervous system o Blood and heart (circulatory system) -› vital communicative role in the body § Slower messenger system than nerevous system Carries chemicals that aBect both physical growth and behavior Among these chemicals: hormones o Hormones: chemical messengers secreted naturally into the blood § Carried by blood to all the body where they act on speciﬁc target tissues § Classic hormones – best understood Secreted by special hormone-producing glands = endocrine glands (pic) § many other hormones secreted by other organs that are such as stomach, intestines, kidneys, and brain o How hormones aBect behavior § ABect the growth of peripheral bodily structures (muscles and bones) -› inﬂuence bheavioral capacity § ABect metabolic processes throughout the body -› inﬂuence amount of available energy for action § Also act in the brain and inﬂuence drives and moods § Some eBects are long term and irreversibel and some of these occur before birth Anatomical diBerences between sexes -› caused by androgens (e.g. testosterones) -› both physical and mental diBerences At puberty -› increased production of sex hormones (testosterone and estrogen) -› new set of growth processes that further diBerentiate males and females anatomically and thereby inﬂuence their behavior. § short-term eBects of hormones range in duration from a few minutes to many days. response to stressful stimulation -› adrenal cortex ( external layer of the adrenal gland) secretes various stress hormones, including cortisol-› produce eBects that help in a stressful situation (release sugar and fat molecules into blood to supply extra energy for “ﬁght or ﬂight,” suppress inﬂammation caused by wounds) o These hormones also taken up by neurons in certain brain parts and act there to help adapt behaviorally to the stressful situation o How hormones are controlled by the brain § Pituitary: Master endocrine gland Produces hormones that stimulate the production of other hormones in other glands (adrenal cortex and gonads (ovaries and testes)) Relationship between the brain and pituitary o rear part of the pituitary (posterior lobe) is a part of the brain consisting mainly of modiﬁed neurons, referred to as neurosecretory cells, which extend down from the hypothalamus § When activated by brain neurons that lie above them, they release their hormones into a bed of capillaries -› transported into the rest of the circulatory system to aBect various parts of the body. o Anterior lobe: § Not part of brain (no neurons descend into it) § But connected to it by specialized set of capillaries §Neurosecretory cells in hypothalamus produce releasing factors, hormones that are secreted into the special capillary system and are carried to the anterior pituitary, where they stimulate the anterior pituitary cells to synthesize and release hormones into capillaries that carry the hormones into the bloodstream § DiBerent releasing factors, produced by diBerent sets of neurosecretory cells in the hypothalamus, act selectively to stimulate the production of diBerent anterior pituitary hormones. Sequence of hormonal events triggered by the brain o (1) A shadowy ﬁgure is seen at night, and brain interprets it as fearsome o (2) The association cortex sends a neural message to the viewer’s hypothalamus that causes it to secrete corticotropin-releasing factor o (3) The specialized capillary system transports this releasing factor to the anterior pituitary, where it stimulates the release of another hormone, corticotropin, into the bloodstream o (4) From the bloodstream, corticotropin enters the adrenal cortex, where it causes the release of adrenal cortical hormones, including cortisol o (5) These adrenal hormones are carried throughout the body to help prepare it for a possible emergency. o At the same time, many other brain-controlled eBects are occurring to deal with possible emergency suggested by the sight of the shadowy ﬁgure (activation of the sympathetic portion of the autonomic nervous system, development of a plan to escape) o Hormonal inﬂuence on sex drive § Hormonal inﬂuences on male sex drive Most crucial hormone is testosterone o Produced by the testes Medical preoptic area o Part of hypothalamus o Neurons here contain many receptor sites for tesotsterone Amount of testosterone men secrete into their blood aBected by psychological conditions. conditions that promote self-conﬁdence tend to increase a man’s production of testosterone § Hormonal inﬂuences of female sex drive After puberty -› ovaries secrete estrogen and progesterone on a cyclic pattern -› menstrual cycle in humans, estrous cycle in other mammals o Controls ovulation (release of one or more eggs so that pregnancy can occur) o Cycle of hormones also inﬂuences sexual drive § Only seeking opportunities for mating when ovulating for mammals § Human can experience high or low sex drive at any time in their hormonal cycle Hormonal activation of drive has been taken over largely by adrenal androgens (= category of homones, including testosterine, produced by the testes in male animals and are normally thought of as “male hormones.”) These hormones are also produced at lower levels by the adrenal glands, in females as well as in males o Although ovarian cycle does not control women’s sexual drive -› evidence that it inﬂuences it to some degree. § women are signiﬁcantly more motivated sexually at the time in their cycle when they are fertile than at other times. § Hemispheric diBerences in the cerebral cortex o Nearly all part of the brain exists in duplicate § Most evident in the cerebral cortex § Two hemispheres connected by a massive bundle of axons called the corpus callosum located below the ﬁssure § Hemispheres quite symmetrical in their primary sensory and motor functions Same job for diBerent half of the body o Most neural paths between the primary sensory and motor areas of the cortex and the parts of the body to which they connect are crossed, or contralateral. § -› Sensory neurons in the right side of the skin send signals to the somatosensory area of the left hemisphere § This symmetry breaks doen in association areas § Most obvious distinction between the two cortical hemispheres in humans: Large areas in the left specialised for language Comparable areas in the right specialised for nonverbal, visuospatial analysis of info o EBects of surgical separation of the hemispeheres: split brain, split mind § Last-resort treatment for epilepsy to cut two hemispheres by cutting the corpus callosum No serious aftereBect But under special conditions where info is provided to just one hemisphere -› split brain people behave as thogh they have to separate minds with diBerent abilities § How each hemisphere can be tested separately after the split- brain operation Split-brain studies examine the crossed sensory and motor connections between the brain and peripheral parts of the body. each hemisphere most directly controls movement in, and receives somatosensory information from, the opposite half of the body. o connections from eyes to the brain: input from the right-hand half of a person’s ﬁeld of view goes ﬁrst to the left hemisphere, while input from the left visual ﬁeld goes ﬁrst to the right hemisphere. In normal brain: all info that goes to either hemisphere subsequently travels to the other through the corpus callosum o split-brain surgery destroys those connections o with split brains as subjects, it is possible to § (a) send visual information to just one hemisphere by presenting the stimulus in only the opposite half of the visual ﬁeld § (b) send tactile (touch) information to just one hemisphere by having the subject feel an object with the opposite hand § (c) test the knowledge of just one hemisphere by having the subject respond with the hand opposite to that hemisphere. § § Split-brain evidence for left-hemisphere language and right- hemisphere spatial ability § How patients with split brains can cope as well as they do Sometimes conﬂicts where the left hemisphere wins But most often no conﬂict due to several coordination mechnaisms o They only cut the upper bridge o Info can still travel on the lower routes o More competent hemisphere takes over in a given task o Hemispheres learn to communicate indirectly -› cross-cueing= observing and responding to the behavior that the other produces § Split-brain insight into consciousness: the left-hemisphere interpreter When asked to explain some behavior triggered by the right hemisphere, the person (speaking from the left hemisphere) usually generates quickly and conﬁdently a seemingly logical (but often false) explanation Conclusion: one natural function of the left hemisphere is to interpret , or make logical sense of everything a person does o Role to tell stories both to the person and to others, desinged to make sense of the seemingly contradictory and irrational things one does o Centerpiece of Freud’s theory of consciousness: § we do things because unconscious decision- making processes in our mind make us do them. But one part of our mind observes what we do and tells a running story about it; that story constitutes our conscious understanding of our actions and the reasons for them o Language areas of the left hemisphere § Much of the left hemispehre of the human cortex involved with language § Aphasia = any loss of language ability reulting from brain damage classiﬁed into a number of types, depending on the speciﬁc nature and degree of loss § EBects of damage to Broca’s area Area of the left frontal lobe (Broca’s area) anterior to the primary motor area Speech becomes labored and telegraphic (min number of words are used to convey the message) o Mostly nouns and verbs, rarely longer than 3-4 words Disorder: Broca’s aphasia / nonﬂuent aphasia o Neurons in Broca’s area are crucial for ﬂuent speech production -› lies close to motor areas controling speech muscles o + diBiculty understanding language especially transforming grammatically complex sentences into simpler ones in order to extract the meaning. § EBects of damage to Wernicke’s Area Wernicke’s area: left temporal lobe, near the primary auditory area Wernicke’s aphasics: diBiculty understanding the meaning of words and ﬁnding appropriate words to express meaning they want to convey Speech of these patients almost opposite of Broca patients o Rich in little words that serve to form the grammatical structureof a sentence (articles, prepositions, conjunctions) but very deﬁcient in nouns, verbs, adjectives o inability to come up with the correct names of objects and actions leads to a heavy use of pronouns and nonsense words as substitutes o speech retains its ﬂuency and grammatical structure but loses its meaning disorder = Wernicke’s aphasia/ﬂuent aphasia o neurons in this area as involved in translating the sounds of words into their meanings and in locating, through connections to other cortical association areas, the words needed to express intended meanings § identifying language areas through neuroimaging with PET and fMRI we can determine which areas of the brain become more active when a person enbgages in a language-related task results: o viewing or hearing words, without having to act on them in high activity in the relevant sensory areas: visual areas of the occipital lobe for viewing and auditory areas of the temporal lobe for hearing o Repeating aloud words resulted in high activity in areas of the primary motor cortex that are involved in control of the vocal apparatus. o Generating appropriate verbs in response to seen or heard nouns resulted in high activity in an area of the frontal lobe that encompassed Broca’s area and in a portion of the temporal lobe somewhat behind Wernicke’s area § Changes in the brain over time o Neurons are soft, pliable living cells § can change their sizes, shapes, excitabilities, and patterns of connections in ways that help adapt their changing circumstances. o brain not only changes during the span of an individual’s life; it has also changed over the course of evolution. o If you use it, it will grow § Regions of the brain tend to groe when used and antrophy when not § EBects of deprived and enriched environments on the brain brains of the enriched group had thicker cerebral cortexes, larger cortical neurons, more acetylcholine (a prominent neurotransmitter), more synapses per neuron, and thicker, more fully developed synapses than did those of the dperived group increases in learning ability they proved that contrary to prior belief, new neurons are constantly being generated in some parts of the brain, including the adult human brain o mostly in the hippocampus (known to be involved in learning and memory) § restructuring of the cortex during skill development As an animal or person develops skill at a task, ever more neurons in the brain are recruited into the performance of that skill. o E.g. blind people’s heightened senses § Spatial learning and growth of the hippocampus Hippocampus involved in memory, especially for spatial locations o hippocampal enlargement depends at least partly on experience o extensive spatial learning can increase hippocampal suze in humans too o strengthening of synapses as a foundation for learning § the hebbian synapse: neurons that ﬁre togther wire together hebb: some synapses in the brain have the property of growing stronger (more eBective) whenever the postsynaptic neuron ﬁres immediately after the presynaptic neuron o neurons could acquire the capacity to respond to input that they previously didn’t respond to. o basis for classical conditioning and other forms of learning o Timothy Bliss and Terge Lømo discovered phenomenon called long-term potentiation(LTP), § o When neuron A becomes active, some of the neurotransmitter molecules it releases become bound to conventional, fast-acting receptors on the postsynaptic membrane, where they produce a depolarization that is too slight to play a signiﬁcant role in triggering action potentials. o Other transmitter molecules at the same synapse, however, become bound temporarily to special LTP- inducing receptors on the postsynaptic membrane. If neuron C then ﬁres an action potential (due to input from other neurons, such as B), the combination of that ﬁring and the presence of transmitter molecules in the LTP-inducing receptors triggers a series of biochemical events that strengthen the synapse o The presynaptic terminal becomes larger, able to release more transmitter substance than it could before, and the postsynaptic membrane develops more conventional receptor sites than it had before. o As a result of such changes, ﬁring in neuron A produces more depolarization in neuron C than it did before and therefore plays a greater role in triggering action potentials in that cell than it did before. § Evidence that log-term potentiation is a basis for learning LTP involved in learning Increase LTP -› increase memory in mice o The evolution of the human brain § brains change over the course of an individual’s development and in response to learning § but also longer evolutionary change brain orgaization similar in all mammals change over evolution: amount of volume dedicated to the associative areas of the brain relative to the sensory and motor areas Most prominent feature of human brain is its size Encephalization quotient (EQ): formula for evaluating the expected ratio between brain weight and body weight for animals In-class notes: - Observer-expenctancy: clever hans - Participant – expectancy eBect : placebo - Neurons: o Electrical sinals going up to he brain and down to the body o Neurons: dendrite (connection to other cells), cell body (with nucleus), axon, axon terminals (connection to other cell), myelin sheath § Axon terminals connect to the dendrits of another neurons o Signals(electrical activity) always goes from cell body to axon § Due to diBerent ions Na+, Cl-, a-, K+ § Movement of positive and negative ions around the membrane that generate these electric signals o Sensory neurons – carry infor from sensory organs into central nevous system o Motor neurons? Carry infor out from the brain to the muscles and glands o Interneuron: carry ifnor within the central nervous syystem § Collect, orgnaize, and integrate info § They generate our consciousness § Ensuring connection between neurons – between sound and vision, motor and sensory neurons o Communication between neurons -› neuronal signalling § Sodium, potassium, chloride, proteins -› basis of electrolytes § Gates or pumps that let these elements through -› causes change in electronic activity of the neuron -› action potential § In restig position. All neurons have a slightly negative potential by default To send a signal – raise electrical potential from -70 to -50 (make it more positive) and then it shoots a signal

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