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Unit 1: Biological Bases of Thought and Behaviour esearch Methods 1 R Two Reasons to Love Research Methods It allows you to get at the why question It allows you to critically evaluate the conclusions that others have reached Step 1: Coming up with a research quest...
Unit 1: Biological Bases of Thought and Behaviour esearch Methods 1 R Two Reasons to Love Research Methods It allows you to get at the why question It allows you to critically evaluate the conclusions that others have reached Step 1: Coming up with a research question, and making a prediction about the expected relationship between variables (i.e., a hypothesis) Example: Research question: Is there a relationship between watching violence on TV and aggressive behavior in children? Translate into a testable prediction: ○ H0: There will be no differences in the number of aggressive behaviors between children who watch a violent TV show and children who watch a nonviolent TV show. ○ H1: Children who watch a violent TV show will exhibit more aggressive behaviors than children who watch a nonviolent TV show. Step 2: Design a study to test your hypothesis! First, operationalize your variables ○ Define your variables in a way that allows you to test your hypothesis ○ Example: H1: Children who watch a violent TV show will exhibit more aggressive behaviors than children who watch a nonviolent TV show. How should we operationalize each of these variables? Different types of designs: ○ Experiments ○ Correlational studies Determine whether a causal relationship exists between two or more variables. Hallmarks of Experiments ○ Independent Variable – manipulated by experimenter, hypothesized to cause some effect on another variable Different conditions are called different levels Important to have a control group, which does not get the manipulation, as a comparison ○ Dependent Variable – also called the “outcome” variable, it is the variable that is hypothesized to be affected ○ “We want to test the effects of ________ on ________.” Example: C hildren who watch a violent TV show will exhibit more aggressive behaviors than children who watch a nonviolent TV show. Independent Variable: Type of television show (violent vs. nonviolent) Dependent Variable: Number of aggressive behaviors (as operationally defined) ○ Random Assignment: each person has an equally likely chance to get placed in each condition ○ In experiments, we try to vary one factor (the IV) and keep other aspects of the situation constant. Only then can we say the IV “caused” the DV. ○ Studies can be between-subjects or within-subjects Between-subjects = participants are in separate conditions (i.e., they are exposed to only 1 level of the independent variable Within-subjects = participants are in multiple conditions (i.e., the same subjects are exposed to multiple levels of the independent variable) ○ Studies can be blind or double-blind Blind experiment – subject is ‘blind’ to treatment condition Double-blind experiment – Observer and subjects are both blind to treatment condition Causation 1. Covariance ○ The IV and the DV should covary/co-occur/be correlated 2. Temporal precedence ○ The IV (the cause) should clearly come first in time, before the DV (the effect) 3. No plausible alternative explanations ○ Keep as much constant as possible between the experimental and control conditions Research Methods 2 Correlational Designs Correlational research measures statistical relationship between two or more variables. (No experimental manipulation of variables; no IV) Correlation coefficient (“r”) – ranges from -1.0 to +1.0 Positive correlation = when one variable increases, the other variable increases Negative correlation = when one variable increases, the other variable decreases Correlation does not equal causation Key Concepts for Research Reliability→Does your measure consistently achieve similar results? Validity→Is your measure accurate? Construct validity→Do you have good operationalizations? ○ ○ External validity→Do your results generalize? ○ Internal validity→Can you rule out alternative explanations? Step 3: Analyze the data Results support the hypothesis or results do not support the hypothesis? Statistics = measurements of samples, in order to make an inference about the broader population Descriptive Statistics Central tendencies = summarizes the entire data set ○ Mean = “average” (sum of scores / number of scores) ○ Median = when data are ordered from lowest score to highest score, median divides the group of scores in half ○ Mode = most frequently occurring score(s) Variability = how the sample is spread out from the mean in one or both directions ○ Standard deviation (average deviation, or difference, of a score from the mean) 68% of data falls within one standard deviation of the mean 95% of the data falls within 2 standard deviations of the mean Inferential statistics Allow us to generalize findings from our sample to our population Establishing the confidence that results are not due to chance (determine the likelihood of obtaining a particular value for a sample, given that the null hypothesis is true) Probability of a chance finding (p-value) is the significance level Convention is that we accept 5% chance or less Step 4: Interpret the results and plan further research enes and Inheritance (Behavioral Genetics) G Nature vs. Nurture Behavioral Genetics The role of genetics in behavior and trait variation Genes Build and modify physical aspects of the body Code and regulate protein production Indirectly affect behavior Behavioral Genetics: Important Terms Genotype: Set of inherited genes Phenotype: Observable traits/behaviors associated with genes and the environment Monozygotic twins: Individuals who are genetically identical Dizygotic twins: Fraternal twins, same degree of genetic similarity as any non-twin siblings Concordance rate: If one twin has a particular trait, the likelihood of the other twin having the same trait Nature vs. Nurture / Genes vs. Environment What do we mean by genes? ○ Gene = segment of a DNA molecule that forms/modifies the anatomy and physiology of the body via building/activating proteins. What do we mean by environment? ○ Everything else. For example… Prenatal environment(in the womb) Early experience Peer influence Physical features of the environment Cultural norms It’s not one or the other – it’s both! Gene BY Environment interactions A Common Misconception: Number of Genes Most of the normal variability in behavior is due to multiple genes and their interactions with the environment ○ Eye color – 6 genes ○ Skin color – 40 genes ○ Weight – 500+ genes Environments Influence Genes [epigenetics] What about Genes Influence Environments? Passive Evocative Active Genetics and Stress Genes code for the susceptibility for a particular clinical disorder (e.g., anxiety) Stress in the environment can trigger the onset of such disorders Genes code for susceptibility to the environment For those more “sensitive” to their environment, there can be both negative and positive effects Heredity Alleles ○ Genes that occupy same locus on chromosome pairs ○ Dominant genes produce effects no matter pair (hetero- or homozygous) ○ Recessive genes only produce effect with matched pair (homozygous) Autosomal recessive conditions ○ Autosomal: non-sex chromosome ○ Recessive: Carried on a recessive allele ○ With two carrier parents, 25% chance that child will have condition, 50% for carriers, 25% do not carry gene ○ e.g., cystic fibrosis, sickle cell anemia, phenylketonuria (PKU) Evolutionary Psychology Darwin’s Theory of Evolution Charles Darwin, The Origin of Species, 1859 Primary goal of behavior: reproduce All species ○ Share common ancestry (hence, similarities) ○ Have adapted to their environments (hence, differences) Selection occurs… ○ Naturally, through influences on reproductive success, e.g., food ○ supply, mate attraction ○ Artificially, through, e.g., selective breeding Sexual Selection Focused on adaptations that arise due to successful mating (not necessarily survival) Two pathways ○ Intrasexual competition = competition between members of one sex, the outcomes of which determine access to the other sex ○ Intersexual competition = preferential mate choice Theory of Evolution Modern synthesis Genes are the unit of selection ○ Genetic variation ○ Random shuffling of genes (meiosis) ○ Mutations (errors in DNA replication) Cross-Species Comparisons Homology: Any similarity that exists because of different species’ common ancestry ○ Example: Smiling and laughing in both chimps and humans Analogy: Any similarity that exists because of convergent evolution (independent evolution of similar traits) ○ Example: Wings in both birds and bats Parental Investment Theory Key difference between males and females: extent to which they are biologically obligated to invest in offspring Because of these biological differences… ○ The sex that invests more in offspring will be more selective about mating (“choosy”) ○ The sex that invests less in offspring will be more competitive for sexual access to the high-investing sex (“compete”) Fallacies about Evolution Evolution has foresight Naturalistic fallacy All traits are adaptations ○ Vestigial traits—no longer adaptive ○ Byproducts—no actual benefit on its own ○ Exaptations—originally evolved for something else ○ Context—something might be adaptive sometimes, but not always Concluding Points Not everything can be explained by evolution Evolutionary explanations and social/cultural explanations can co-exist; they are not mutually exclusive! Neurons and Synapses Nervous system is a network of neurons that run throughout your brain and body. nerves—collections of neurons—carry signals to and from your brain, relating perceptions, thoughts, and feelings into actions. Spinal cord: major bundle of nerves that connects your body to your brain The nervous system also allows us to have some important behaviors such as reflexes without requiring the brain at all Neuron Fundamentals Neuron = Nerve cell in the brain & nervous system ○ S ensory neuron: Carry messages from sensory organs to CNS. Carry information from within your body and the outside world to your brain ○ Interneuron: Carry messages from one set of neurons to another. They interpret, store, and retrieve information about the world, allowing you to make informed decision before you act ○ Motor neuron: Carry messages from CNS to muscles and glands Divisions of the Nervous System The central nervous system consists of the brain and spinal cord. The peripheral nervous system has two divisions: the somatic nervous system and the autonomic nervous system. Somatic nervous system is related to voluntary commands-or commands that we choose to do ○ not only senses the body, but also controls your conscious body movements ○ includes your skeletal muscles. Autonomic nervous system is related to involuntary commands, those largely not in your control ○ maintains the operations of the inside of your body-for example, your heart-and is mostly outside of your conscious control. ○ includes your organs, blood vessels, and glands, which are hormone-secreting organs ○ branches into the sympathetic and parasympathetic nervous systems sympathetic branch ensures that your body provides essential resources needed for the fight-or-flight response, To make fight-or-flight possible, your body redirects energy from processes that are not essential in the moment, such as digestion and sexual reproduction. a cts on blood vessels, organs, and glands in ways that prepare the body for action, especially in life-threatening situations The parasympathetic nervous system acts on blood vessels, organs, and glands in a way that returns the body to a resting state by both counteracting and complementing the actions of the sympathetic system. The restorative function of the rest-and-digest response allows you to regenerate the energy that your body needs when it is safe to do so. Eating is one important restorative activity. "Emotional eating" is their attempt to regulate stress by engaging the parasympathetic nervous system's anti-stress response. Although often working in opposition to each other, the sympathetic and parasympathetic nervous systems work together to prepare the body for the challenges that the brain sees lying ahead. The Structure of Neurons Cell Body: The cell body collects neural impulses, contains the nucleus, and provides life-sustaining functions for the cell Dendrites : receive chemical messages from other neurons. The axon: transports electrical impulses called action potentials to the terminal branches, where they are converted into chemical messages that are sent to other neurons. Myelin: is a layer of fatty tissue that covers and insulates the axon to ensure electrical messages are kept intact and travel quickly. ○ Degradation of myelin, called demyelination, is a central characteristic of neurodegenerative diseases ○ Shrinks with aging ○ Glia: cells that make up the myelin. Insulate, support, and nourish the neuron. Serve as cellular glue contribute to information processing during childhood development and into adulthood Are essential for brain development, providing a scaffold along which axons grow and guiding them to their correct location in the nervous system A id in the formation of neural networks: cluster of cells that work together as a functional unit Terminal branches: convert electrical signals into chemical messages that they then send to other neurons. Action Potential and How Nerves Fire Them Neurons are bathed in extracellular fluid composed of positively and negatively charged particles or ions (sodium (NA+), chloride (Cl-), potassium (k+), and calcium (CA2+)) The membrane that separates the intracellular (inside the cell) and extracellular (outside the cell) fluids is selective, which means that only certain ions can pass through the membrane to the inside of a neuron Normally, at resting potential, positively charged ions are outside the cell so the intracellular fluid is relatively positive compared to the negative intracellular environment ○ A neuron cannot fire an action potential as long as this resting potential is strongly negatively polarized If a neuron is stimulated sufficiently to pass its voltage threshold, an action potential fires ○ When other neurons sufficiently stimulate a neuron’s dendrites ion changes open allowing positively charged sodium (Na + ) ions into the neuron. As these positively charged ions flood into the neuron, they set off a chain reaction as they spread down the axon, causing more channels to open. 1) Depolarization: occurs when the voltage of a neuron becomes less negatively polarized and moves toward and past a critical voltage threshold to fire an action potential. a) positive ions flowing into the axon. 2) Voltage threshold: the critical voltage(around -50 millivolts) that the neuron must reach to fire an action potential. The neuron's voltage then surges rapidly and becomes positive as it passes zero. 3) Repolarization: occurs as the neuron returns to its resting state voltage a) positive ions flowing out of the axon. 4) Refractory period: is the time required before a neuron is able to fire its next action potential a) during which it is difficult or impossible to get a neuron to fire an action potential again Neuron Signals One of two kinds: Excitatory or Inhibitory e xcitatory messages: move the voltage of the neuron closer to its threshold. inhibitory messages: move it farther away from its voltage threshold. ○ If the excitatory (positive/+) messages outweigh the inhibitory (negative/-) messages enough to reach the voltage threshold, then the neuron fires an action potential ○ If the neuron receives many inhibitory (negative/-) signals, it is much less likely to reach the threshold necessary for firing. Neurotransmission: How Neurons Communicate Synapse: The gap where a sending neuron communicates with the dendrites or the cell body of the receiving neuron The process of neurotransmission allows the electrical message to bridge the synaptic gap by converting the electrical signal into a chemical one, thus allowing neurons to transmit their signals to one another. Electrical-to-chemical translation is critical for communication between neurons-from the sending presynaptic neuron's terminals to the receiving postsynaptic target neuron's dendrites Without making anatomical contact, the terminal branches release chemical messengers called neurotransmitters , across the synaptic gap toward the target, receiving neuron On the surface of target neurons are receptors that recognize and bind with specific neurotransmitters. Each neurotransmitter has specific receptors that selectively recognize it. 'Thus, each receptor is like a lock with a key-a neurotransmitter-that will open it. Once the neurotransmitter binds to its receptor ion channels open hereby inducing changes in on flow across the target neurons cell membrane. As a result an electronic signal is generated in the target neuron Receptor Response to Neurotransmitters Receptors targeted by neurotransmitters produce excitatory or inhibitory electrical signals in the target neuron Ions enter the receptor, moving the target neuron closer to or farther from its action potential threshold The receptor's response, not the neurotransmitter itself, determines whether the signal is excitatory or inhibitory Neurotransmitter Inactivation Inactivation of neurotransmitters in the synapse is crucial after signal generation P revents constant stimulation and maintains neuronal balance Mechanisms for neurotransmitter removal: ○ a) Diffusion: Neurotransmitters drift out of the synapse into extracellular space ○ b) Degradation: Chemical reactions break down neurotransmitters in the synapse ○ c) Reuptake: Presynaptic terminals reabsorb neurotransmitters Antidepressants and Neurotransmitter Function Some antidepressants prevent neurotransmitter reuptake Selective Serotonin Reuptake Inhibitors (SSRIs) keep neurotransmitters in the synapse longer Can be helpful for depression but may cause side effects like upset stomach or insomnia Class of neurotransmitters Amino acids: such as glutamate and gamma-aminobutyric acid (GABA), are the brain’s most abundant neurotransmitters Monoamines: are important for fight-or-flight response activation Acetylcholine: can behave as both an inhibitory and an excitatory signal. It supports heart and skeletal muscle, and cognitive function. Brain Mapping and the Nervous System Terminology: The Compass of the Brain Brain Structure CEREBRAL CORTEX Frontal lobe ○ ○ Parietal lobe ○ Temporal lobe Occipital lobe (Insular lobe) SUBCORTICAL STRUCTURES ○ Basal ganglia ○ Hippocampus ○ Amygdala ○ Thalamus and hypothalamus ○ Corpus callosum OTHER ○ Brainstem ○ Midbrain ○ Pons ○ Medulla oblongata ○ Reticular formation ○ Cerebellum Brain Mapping Caveats Certain parts of the brain are responsible for certain functions, but… ○ Individual differences ○ Most behaviors require multiple areas ○ Brain can reorganize through early experience or reaction to trauma “plasticity” Major Brain Divisions The brain is organized into three major structures during development: ○ Forebrain ○ Midbrain ○ Hindbrain The Cerebral Cortex T he cerebral cortex is the largest and outermost portion of the human brain, supporting complex mental activity. Neocortex The majority of the cerebral cortex is neocortex, which: ○ Is evolutionarily the youngest part of the brain ○ Develops through late adolescence and young adulthood ○ Supports complex functions like language, thought, problem-solving, and imagination ○ Is extensively folded to accommodate a large number of neurons Cerebral Hemispheres and Lobes The cerebral cortex is divided into two hemispheres, each with subdivisions called lobes: 1. Occipital Lobe Located at the back of the head Primarily devoted to vision Contains the primary visual cortex 2. Temporal Lobe Runs alongside the ears Contains the primary auditory cortex Responsible for hearing, language understanding, and object/people recognition 3. Parietal Lobe Located above and behind the ears Contains the primary somatosensory cortex Supports body mapping, sense of touch, and attention to visual world 4. Frontal Lobe Located in the front of the head Contains the primary motor cortex Includes the prefrontal cortex, responsible for thought, planning, decision-making, and self-control 5. Insular Lobe Hidden under the temporal, frontal, and parietal lobes Allows perception of internal body states Includes the primary taste cortex Sensory and Motor Areas Each lobe contains specific sensory and motor areas: Primary sensory areas for each of the five senses Primary motor cortex for voluntary movements Association Cortex The association cortex: Integrates sensory information with existing knowledge Helps interpret and recognize sensory patterns Supports connections between sensory regions and pleasure Is present in every lobe Is responsible for the brain's most sophisticated abilities Comparative Brain Anatomy The cerebral cortex varies among species: Primates have a higher proportion of association cortex compared to other mammals The size of the frontal cortex and number of convolutions differ among species Dogs have a densely packed cerebral cortex, potentially supporting a rich mental life The Subcortical Brain: Emotion, Motivation, and Memory Subcortical Structures S ome of these subcortical structures are older forms of cortex, but most are clusters of cells, called nuclei, that are very distinct from the cortex. The Limbic System ○ The limbic system bridges the newer, higher brain structures that are more related to complex mental functions with the older, lower, brain regions that regulate your body and its movements (MacLean, 1990). The limbic system consists of multiple interconnected yet distinct structures, including the hippocampus, amygdala, basal ganglia, thalamus, and hypothalamus (FIGURE 3.14). The limbic system is often described as the "emotional brain," but that description is not entirely accurate because the limbic system also plays important and diverse roles in smell, learning and memory, and motivation (Nishijo et al., 2018). Hippocampus ○ One of the best-understood limbic structures, the hippocampus, is crucial for certain aspects of memory and your ability to navigate the environment (Maguire et al., 2006). The hippocampus is an older region in the depths of the temporal lobe that creates memories of an event's time and place, supporting mental time-travel into the past (Moscovitch et al., 2016). The hippocampus is related to emotions insofar as it helps you remember emotionally prominent events from your life and think about your hopes and desires for your future (K. L. Campbell et al., 2018). Amygdala ○ An essential component of the limbic system that is dedicated to emotion is the almond-shaped amygdala (Latin for "almond"), which is cradled in the outstretched arms of the hippocampus. It plays an essential role in how you register the emotional significance of events. In lab animals, the removal of the amygdala can dramatically change emotional behavior. A once-ferocious animal may become tame, and fearful animals may become fearless. As FIGURE 3.15 shows, a rat without an amygdala will snuggle up to a predator, a cat -at least a partially sedated one (C. I. Li et al., 2004). ○ Abnormalities in the amygdala can result in what was once called psychic blindness: Animals could still see, but the psychological importance of what they saw appeared to be absent. Because the amygdala is one of the most interconnected regions of the brain, it touches on many aspects of what the brain does, including how you see, think, and remember (Pessoa, 2008; Todd et al., 2013). Your most vivid memories are likely to be emotionally significant, and the amygdala enhances these memories by influencing the hippocampus (Cahill & McGaugh, 1998; LaBar & Cabeza, 2006; Roozendaal et al., 2009). Basal Ganglia ○ The basal ganglia are a group of interconnected structures that are an evolutionarily older subcortical motor system that is necessary for planning and executing movement. They bridge the motor regions of the cerebral cortex with nuclei that communicate with the spinal cord, sending signals to your muscles to act. Degeneration of the basal ganglia results in slow, rigid, tremor-filled movements or involuntary writhing, suggesting that the basal ganglia are critical for both starting and stopping (or inhibiting) movement. Parkinson's disease, which affects the basal ganglia, compromises the ability to plan, initiate, execute, and control movement (A. B. Nelson & Kreitzer, 2014; Zhuang et al., 2017), leading to a substantial difficulty in initiating actions that results in slow movements and tremors. As we will discuss, certain components of the basal ganglia are also involved in learning and motivation, the psychological forces that will us to move. Thalamus ○ Located between the basal ganglia and resembling two large symmetrical eggs, the thalamus serves as a central subcortical hub for the signals it receives from all of the sensory systems except the olfactory (smell) system. There is two-way communication between the thalamus, which sits deep in the middle of the brain, and the brain regions that receive its messages. This communication is critical to how your brain determines what is out there in the world (Rauss et al., 2011) ○ As you sleep, the thalamus helps you shut out the outside world by turning down its relaying of sensory inputs. In dreams, your world becomes one with the possibilities your brain can imagine. Because the thalamus plays a central role in relaying sensory information to and from the cerebral cortex, damage to it can result in a wide variety of impairments, from loss of touch, to blindness, to memory loss. Hypothalamus ○ Despite its small size, the hypothalamus, which sits below the thalamus, is the major interface between the brain and the body, integrating internal bodily signals with their associated feelings and behaviors. Like the thalamus, the hypothalamus is composed of many specialized nuclei that regulate specific functions, including hunger, biorhythms, reward seeking, and aggression. The Brainstem and Cerebellum: Key Components of the Central Nervous System The Brainstem ○ Overview Located at the base of the skull Regulates vital functions like breathing and heart rate Connects most sensory nerves to the brain Evolutionarily oldest and most primitive brain region Structure From top to bottom ○ Midbrain Pons ○ ○ Medulla oblongata ○ Reticular formation (runs through the brainstem) Functions of Brainstem Components Midbrain ○ Includes the tegmentum for reflexive head and eye movements ○ Contains the ventral tegmental area, part of the motivation and reward system ○ Houses the substantia nigra, involved in movement regulation Pons ○ Controls breathing rate ○ Relays sensations like hearing, taste, and balance Medulla Oblongata ○ Controls autonomic functions (heart rate, blood pressure) ○ Manages critical reflexes (coughing, swallowing) Reticular Formation ○ Central to arousal and attention ○ Regulates sleep and wakefulness ○ Plays a role in ADHD ○ Important for maintaining cognitive abilities with age The Cerebellum Overview ○ Located behind the pons and medulla in the hindbrain ○ Shaped like a small brain at the back of the brainstem Functions ○ Contributes to coordination, precision, balance, and accurate timing ○ Adjusts head and eye movements for balance ○ Critical for learning precision movements ○ Plays a role in thought and planning Importance in Movement and Cognition ○ Enables complex and detailed movements (e.g., sports activities) ○ Involved in mental practice for learning movements ○ Increasingly recognized for its role in overall cognition Neural Plasticity: Key Concepts and Implications Neural plasticity refers to the brain's ability to physiologically modify, regenerate, and reinvent itself throughout a lifetime. Key Concepts Critical Periods ○ Early life stages where specific experiences are crucial for normal development ○ Example: Cataract removal in infants for normal face recognition ability Damage Plasticity ○ Neural modification following injury ○ Involves brain reorganization in response to altered inputs Adult Plasticity ○ Shaping and reshaping of neural circuits in adulthood ○ Examples: Learning to navigate complex city streets, practicing musical instruments Mechanisms of Neural Plasticity Synaptogenesis ○ Generation of new synapses between neurons ○ Supports learning and memory Neurogenesis ○ Birth of entirely new neurons throughout the lifespan ○ Potentially involved in new memory formation ○ May be related to stress and depression Conclusion Understanding and harnessing neuroplasticity offers promising avenues for improving human lives and treating various neurological conditions. rain Function and Lateralization B Functional Categorization Primary sensory areas Primary motor area Association areas Lobes of the Brain Frontal lobe ○ Executive function, risk-taking, planning, creativity, emotions, smell, muscle movements, personality...and much more! ○ Includes the prefrontal cortex, the primary motor cortex, Broca’s area (left hemisphere) ○ Disorders associated with the frontal lobe Apraxias = disorders of action Aphasias = disorders of language (e.g., Broca’s/nonfluent aphasia) Personality… Parietal lobe ○ Perception, pain, integration of sensory input ○ Includes the primary somatosensory cortex ○ Disorders associated with the parietal lobe Agnosias = disorders of perception Prosopagnosia = difficulty recognizing faces Astereognosis = inability to recognize common objects by feeling them Occipital lobe V ○ ision, color perception ○ Includes the primary visual cortex ○ Disorders associated with the Occipital Lobe Impaired visual recognition Blindness Brain Lateralization Hemispheres are symmetrical with respect to primary sensory and motor functions (same job, different half of the body - contralateral) Association areas have some different functions Left & Right Hemisphere Functions LEFT ○ Language ○ Logic ○ Analytical thought RIGHT ○ Spatial relations ○ Facial recognition ○ Perceiving emotion Intuitive thought ○ Musical ability Individual Differences Handedness ○ Left-handers & language: 70% on the left 15% on the right 15% both hemispheres Gender ○ Men are more lateralized for language than women Evidence of Hemispheric Asymmetry “Split-brain” patients Prosopagnosia Demo How can we study lateralization in people without split brains? Reaction time – takes slightly more time for info to go from right hemisphere to left hemisphere, compared to going only to the right hemisphere fMRI scanning to localize active brain regions Transcranial magnetic stimulation temporary brain damage!* *(no actual brain damage; makes it so that particular neurons cannot fire, temporarily; perfectly safe!) Contralateral transmission Hemispatial Neglect Most commonly a result of damage to the right parietal cortex; left visual field is affected ○ An issue of attention, not vision Lateralization Conclusions Despite the split-brain examples… The two sides of our brain are constantly working together Both hemispheres are responsible for complex human capacities Don’t believe the popular press—being ‘left- or right- brained’ is too simplistic Two Hemispheres, One Mind: Understanding Brain Lateralization 1. Brain Symmetry and Function The brain has anatomical symmetry, similar to most body organs Each hemisphere has corresponding structures, but functions are not always equally divided Early studies revealed left hemisphere dominance for language 2. Hemispheric Specialization Broca's area (left frontal lobe): Important for speech production Wernicke's area (left temporal lobe): Crucial for speech comprehension Left hemisphere: Usually dominant for language Right hemisphere: Silent but important partner in language processing 3. Corpus Callosum: The Brain's Bridge Connects the two hemispheres, allowing information sharing Supports contralateral communication between brain and body Can be severed in split-brain procedures to treat severe epilepsy 4. Contralateral Organization Right side of the body is controlled by the left hemisphere, and vice versa Applies to sensory information and motor control Visual information from each side of the visual field goes to the opposite hemisphere 5. Split-Brain Studies Roger Sperry's Nobel Prize-winning experiments Revealed independent functions of right and left hemispheres Demonstrated how each hemisphere processes information separately in split-brain patients 6. Hemispheric Differences Left hemisphere: More involved in verbal and conceptual tasks, focuses on details Right hemisphere: More engaged with perceptual and some emotional tasks, focuses on the big picture Myth debunked: People are not strictly "left-brained" or "right-brained" 7. Unified Mind The singularity of our mind and self results from the cooperation between hemispheres Both hemispheres work together in daily life for normal brain function tress and Health S Biopsychosocial Model of Health’ Biopsychosocial Model & Stress “A physiological response to an environmental event that is perceived as taxing or even exceeding one’s ability to adapt” Uncertainty Lack of control Concern with being evaluated and/or being treated negatively by others General Adaptation Syndrome Alarm Stage ○ “Fight or flight” ○ Increased heart rate ○ Palms sweat ○ Release of cortisol and epinephrine ○ Stress resistance is low Resistance Stage ○ Greater cardiovascular support ○ Greater immunological functioning ○ Stress resistance is high (temporarily) Exhaustion Stage ○ Weakened immune system ○ Inability to physically adapt to ongoing stressor ○ Stress resistance is sharp decline Stress, Health, and Demographics Health disparities: Differences in health outcomes due to various demographic characteristics Higher socioeconomic status (SES) is consistently related to better health outcomes. ○ Access to health care, medicine, and other resources There are also known links between SES and healthy behavior Individuals who believe they have lower status than others in the community: ○ Feel less in control of their experiences ○ Report other negative emotions Can prolong body’s response to stress ○ Find it harder to fall asleep at night Have a higher resting heart rate ○ Are at higher risk of obesity ○ Are more susceptible to illness Motivation and Reward Social Support Social support: The degree to which people believe they can turn to other people for information, help, advice, or comfort. People who report having a larger and more supportive social network have: ○ Lower blood pressure ○ Fewer stress hormones ○ Stronger immune systems ○ A decreased likelihood of depression ○ Increased lifespans Motivation and Reward Broadly, why do we do what we do? Drives motivate us towards rewards. ○ Drives: A state of internal bodily tension, such as hunger, thirst, or the need for sleep Motivate: A force that leads an individual to behave in a particular way ○ ○ Rewards: A positive, pleasurable outcome Homeostasis ○ The body’s tendency to maintain equilibrium through various forms of self-regulation Mammalian Drives for Survival and Reproduction Regulatory drives ○ Towards homeostasis, e.g., hunger, thirst Non-regulatory drives ○ Safety drives, e.g., shelter ○ Reproductive drives, e.g., ○ care/protection of offspring, sex ○ Social drives, e.g., respect, favors, manners ○ Educative drives, e.g., exploration Other Drives ○ Artificial drives, e.g., gambling, addictive substances ○ Aesthetic drives, e.g., art, music, literature, dance Reward Mechanisms Endorphins ○ Are critical for “liking” a reward (receiving a pleasurable stimulus) ○ Opiates bind to endorphin receptor sites Dopamine ○ Is critical for “wanting” (anticipating) a reward ○ Boosts associative learning between stimuli and rewards, including addictive substances and behaviors ○ Released by midbrain neurons terminating in the nucleus accumbens Reward Mechanisms Liking: the subjective feeling of pleasure or satisfaction that occurs when one receives a reward Wanting: the desire to obtain a reward/anticipation of receiving a reward Reinforcement: the effects that rewards have in promoting learning Reward Circuitry Hierarchy of Needs Maslow’s theory of a “hierarchy of needs” suggests that higher-level motives (e.g., esteem, self-actualization) only shape our behavior once lower-level motives (e.g., safety) are fulfilled. Drugs vs. Neurotransmitters Agonists: mimic/enhance the action of a NT Antagonists: oppose/inhibit the action of the NT Example: Acetylcholine, a NT between motor neurons and voluntary muscles ○ Nicotine is an Ach agonist ○ Curare is an Ach antagonist Synaptic Transmission How do drugs influence activity at a synapse? 1) Act on presynaptic neuron (facilitating or inhibiting the synthesis or release of the NT) Ex. Amphetamines 2) Act in synaptic cleft (facilitating or inhibiting reuptake or enzyme deactivation) Ex. Cocaine 3) Act on the post-synaptic binding sites (producing same effect or blocking NT from producing normal effect) Ex. Opiates Intrinsic vs. Extrinsic Motivation INTRINSIC ○ An incentive to engage in a specific activity that derives from pleasure in the activity itself (e.g., a genuine interest in a subject studied) rather than ecause of any external benefits that might be obtained (e.g., money, course b credits) EXTRINSIC ○ An external incentive to engage in a specific activity, especially motivation arising from the expectation of punishment or reward (e.g., completing a disliked chore in exchange for payment) motions E Terminology Emotion: the coordinated behaviors, feelings, and physiological changes that occur when a situation becomes relevant to our personal goals Mood: a short-lived emotional state, usually of low intensity; generally undirected towards any particular target Affect: any experience of feeling or emotion, generally considered along a positive-negative dimension; both emotions and moods are affective states Discrete Emotion Theory The idea that basic emotions are… ○ Innate ○ Universal ○ Identifiable by unique facial expressions ○ Associated with distinctive bodily responses The most common classification identifies 6 primary emotions ○ Happiness, Sadness, Anger, Fear, Surprise, and Disgust But... There is evidence both for and against the idea of discrete, universal emotions Dimensional Approach (some) Important dimensions ○ Valence: Pleasant vs. unpleasant (or positive vs. negative) ○ Activation: High vs. low arousal (or intense vs. mild) ○ Motivation: Approach vs. avoidance Examples Anger = negative / high arousal / approach Excitement = positive / high arousal / approach Sadness = negative / low arousal / avoidance Theories of Emotion James-Lange Theory Cannon-Bard Theory Schachter-Singer Theory Emotion Regulation Up-regulation→strategies to increase an emotion Down-regulation→strategies to decrease an emotion Emotion Regulation Strategies Situation selection: exposing yourself to/avoiding emotional situations Situation modification: changing something about the situation you’re already in Attentional deployment: directing your attention towards/away from the situation/emotional stimulus Cognitive change: changing your interpretation of the situation Response modulation: changing your direct behavioral/physiological response to the situation Emotion and the Brain Amygdala ○ Rapidly evaluates sensory information for its significance to survival or well-being and triggers bodily responses
