FPSH1014 Understanding Self and Others - Biological Psychology PDF

FPSH1014 Understanding Self and Others Topic 2 Biological Psychology Prepared by: Tony Ooi Presented by: Kelvin Wee  Nervous System Cells ❑ Our brain consists of an enormous number of separate cells called neurons. ❑ Nervo...

FPSH1014 Understanding Self and Others Topic 2 Biological Psychology Prepared by: Tony Ooi Presented by: Kelvin Wee  Nervous System Cells ❑ Our brain consists of an enormous number of separate cells called neurons. ❑ Nervous system is our bodies’ command centre (in the brain); controls our movements, thoughts & automatic responses to the world around us. ❑ Neurons = cells of the nervous system that receive information & transmit it to other cells by conducting electrochemical impulses. ❑ A neuron consists of 3 parts: ▪ Cell body ▪ Dendrites ▪ Axon Nervous System Cells ❑ Cell body – contains the nucleus* of the cell. ❑ Dendrites – the widely branching structures that receive input from other neurons. ❑ Axon – a single, long, thin, straight fibre with branches near its tip. ❑ Myelin – an insulating sheath covering the axon that speeds up the transmission of impulses along an axon. ❑ Axon transmits information (sends messages) to other cells; dendrite receives that information (receives messages) from other neurons. *an organelle within a cell that contains genetic code of an organism Action Potential https://www.youtube.com/watch?v=OZG8M_ldA1M  Action Potential ❑ When neurons transmit signals through the body, the transmission process involves an electrical impulse called action potential. ❑ Function of an axon – convey information over long distances; e.g. from skin to spinal cord, from spinal cord to muscle. ❑ Axons convey information by a process called an action potential, ❑ Action potential = an excitation that travels along an axon at a constant strength (no matter how far it travels). ❑ Action potentials are like nerve signals; neurons generate & conduct these signals in order to transmit them to the target tissues. ❑ Example: you want to pick up a glass to drink water action potential carries that message from the brain hand.  Action Potential How Action Potential Works? ❑ Neuron firing takes place as a communication between neurons. ❑ The firing of a neuron involves the action potential process. ❑ The action potential process consists of 3 stages: i. Prior to Action Potential ii. During Action Potential iii. After Action Potential A type of mineral essential to help our body function Action Potential normally. I. Prior to Action Potential ❑ When a neuron isn’t sending signals, the neuron’s: ▪ Inside = negatively charged ▪ Outside = positively charged ❑ The membrane has a resting potential – an electrical polarization across the membrane of an axon. ❑ A mechanism called the sodium-potassium pump: Pushes sodium ions out of the axon. Pulls potassium ions in. ❑ Consequently, sodium ions = more concentrated outside the axon; potassium ions are more concentrated inside.  Action Potential II. During Action Potential ❑ During an action potential: ▪ Sodium gates on axon’s membrane open. ▪ Sodium ions enter axon (carrying a positive charge). ❑ Like how magnet works, sodium ions (highly concentrated outside the membrane) rush into the cell, attracted by negative charge inside. ❑ Influx (flooding) of positively charged sodium ions = action potential. ❑ Positive charge enters axon at one point stimulates next point along the axon starts opening sodium gates repeating the process.  Action Potential III. After Action Potential ❑ After sodium gates have been open for few milliseconds snap shut. ❑ As sodium gates close potassium gates open potassium ions flow out of the axon. ❑ Reasons: ▪ Inside of cell is positively charged (because of sodium ions) no longer attracts potassium ions (positive charge). ▪ Potassium ions are more concentrated inside the cell flow out of the cell, carrying positive charges with them. ❑ Exit of potassium ions inside of the axon back to its resting potential.  Action Potential Highlights of Action Potential ❑ Sodium ions enter the cell (excitation); potassium ions leave (return to the resting potential). ❑ Neuron firing is like a fire burning along a string; fire at each point ignites the next point ignites the next point. ❑ Inside axon, after sodium ions enter some ions diffuse to the neighbouring portion inside the axon exciting the next point enough to open its own sodium gates. ❑ Action potential will spreads to this next point so on down the axon.  Synapse ❑ Our stream of experiences is produced with all neurons communicating with one another. ❑ Neuron communicates with one another by releasing a chemical called a neurotransmitter at a specialized junction called a synapse. ❑ Synapse = the point of contact between neurons where information is passed from one neuron to the next. ❑ Neurotransmitter = chemical that activates receptors on other neurons. ❑ Synapse is a junction of a presynaptic (message-sending) cell and a postsynaptic (message-receiving) cell. ❑ Neurotransmitter can either excite/inhibit the next neuron.  How Neurons Communicate? ▪1 Action potential travels down the axon synapse. ▪2 At the synapse, neurotransmitter is released. 1 Neurotransmitter Terminal bouton = bulge at the end of an axon which releases neurotransmitters 2  How Neurons Communicate? 3▪ Neurotransmitter crosses synaptic cleft binds to the receptors on the surface of the postsynaptic cell (usually on the dendrites). Postsynaptic neuron = neuron on the receiving end of the synapse  How Neurons Communicate? ❑ 4 If binding of neurotransmitter to the receptor cell opens gates for positively charged sodium ions to enter cell will produce more action potential (called excitatory synapse). 4  How Neurons Communicate? ❑ 5 If binding of neurotransmitter to the receptor cell opens gates for positively charged potassium ions to leave cell will produce fewer action potential (called inhibitory synapse). 5  Types of Neurotransmitters Neurotransmitter Functions Comment Glutamate The brain’s main excitatory transmitter, Strokes kill neurons mostly by releasing extra present at most synapses; essential for glutamate that overstimulates them. almost all brain activities, including learning. GABA (gamma-aminobutyric The brain’s main inhibitory transmitter. Anti-anxiety drugs and anti-epileptic drugs acid) increase activity at GABA synapses. Acetylcholine Increases brain arousal. Acetylcholine is also released by motor neurons to stimulate skeletal muscles.  Types of Neurotransmitters Neurotransmitter Functions Comment Dopamine One path is important for movement Most antipsychotic drugs decrease activity at (Reward Chemical) (damaged in Parkinson’s disease). dopamine synapses. L-dopa, used for Another path is important for memory Parkinson’s disease, increases availability of and cognition. dopamine. Serotonin Modifies many types of motivated and Most antidepressant drugs prolong activity at (Good mood chemical) emotional behavior. serotonin synapses. Norepinephrine Enhances storage of memory of All or nearly all axons releasing emotional or otherwise meaningful norepinephrine originate from one small brain events. area, called the locus coeruleus.  Types of Neurotransmitters Neurotransmitter Functions Comment Histamine Increases arousal and alertness. Antihistamines (for allergies) block histamine and therefore lead to drowsiness. Endorphins Decrease pain and increase pleasure. Morphine and heroin stimulate the same (Pain reliever chemical) receptors as endorphins. Nitric oxide Dilates blood vessels in the most active This is the only known transmitter that is a brain areas. gas. Anandamide, 2AG, and Sent by the postsynaptic neuron back to THC (Tetrahydrocannabinol), the active others the presynaptic neuron to decrease chemical in marijuana, stimulates these same further release of transmitters. presynaptic receptors.  Brain & Behaviour ❑ When studying the brain, we can easily get bogged down in memorizing the names & functions of brain areas. ❑ Let’s start with 2 points that are important to remember: i. You use all of your brain. ii. Concept of monism. Continued…  Brain & Behaviour 1. You Use All of Your Brain ❑ You may have heard that “they say” we use only 10% of our brains. ❑ At any moment, some brain areas are more active than usual & others are less active. ❑ However, it’s wrong to assume that you would be smarter if you increased activity in all of your brain. ❑ Inhibition is just as important as excitation. ❑ Useful brain activity requires a pattern of activating some neurons while inhibiting others.  Brain & Behaviour 2. Concept of Monism ❑ Monism = idea that mental activity & brain activity are inseparable. ❑ If you lose part of your brain you lose part of your mind. ❑ You can’t have mental activity without brain activity. ❑ Likewise, you can’t have certain kinds of brain activity without mental activity. ❑ Concept of monism – believes that mental activity = brain activity. Topic 2 Biological Psychology Part 2  Nervous System ❑ The major components of the nervous system are the: i. Central nervous system ii. Peripheral nervous system ❑ Central nervous system (CNS) = consists of the brain + spinal cord. ❑ Peripheral nervous system (PNS) = consists of nerves connecting the spinal cord with the rest of the body. ❑ CNS communicates with the rest of the body by the PNS.  Nervous System ❑ Within PNS, there are 2 types of nervous systems: ▪ Somatic nervous system – connects to the skin & muscles. ▪ Autonomic nervous system – connects to the heart, stomach & other organs. ❑ Sensory nerves bring information from other body areas spinal cord. ❑ Motor nerves take information from the spinal cord muscles (where they cause contractions).  Cerebral Cortex ❑ The vertebrate brain has 3 major divisions i. Hindbrain ii. Midbrain iii. Forebrain ❑ In fish, amphibians, reptile & birds, the midbrain constitutes a large portion of the brain. ❑ In mammals (including humans), the forebrain is by far the largest area. ❑ The forebrain consists of 2 hemispheres: ▪ Left hemisphere ▪ Right hemisphere Continued…  Cerebral Cortex ❑ Each hemisphere controls sensation & movement on the opposite side of the body. ❑ The outer covering of the forebrain, known as the cerebral cortex, is especially prominent in humans. ❑ Cerebral cortex is divided into 4 lobes: i. Occipital lobe ii. Parietal lobe iii. Temporal lobe iv. Frontal lobe  Occipital Lobe ❑ Occipital lobe = area of the cerebral cortex located at the back of the head. ❑ Functions: ▪ Contains the primary visual cortex, which is responsible for interpreting incoming visual information. ▪ Receives sensory information from retinas of the eyes encoded into visual data (e.g. colour, orientation, motion). ❑ Transmit visual information to temporal lobes, which aids in: ▪ Giving meaning to visual information; ▪ Storing memories; ▪ Responding to external stimuli in the world.  Temporal Lobe ❑ Temporal lobe = cortical area located toward the left & right sides of the head. ❑ Function: ▪ Largely responsible for hearing & certain aspects of vision. ❑ Left temporal lobe – understanding language, learning, memorizing, forming speech & remembering verbal information. ❑ Right temporal lobe –learning & memorizing non-verbal information (e.g. drawings, music), recognizing information, & determining facial expressions. ❑ Amygdala = a small structure underneath temporal lobe; primarily involved in the processing of emotions & memories associated with fear.  Parietal Lobe ❑ Parietal lobe = structure just anterior (forward) from the occipital lobe. ❑ Function: ▪ Specialized for body senses, including touch, pain, temperature, & awareness of the location of body parts in space. ❑ Divided into 2 functional areas: i. Sensation & perception – which integrates sensory information to develop a single perception (also known as cognition). ii. Integrating sensory input – mainly visual & aids in constructing spatial maps to represent the world around us.  Frontal Lobe ❑ Frontal lobe = the anterior (forward) pole of the brain, which includes the primary motor cortex. ❑ Function: ▪ Associated typically with ‘higher’ cognitive functions, including decision-making, problem-solving, thought & attention. ❑ Primary motor cortex = brain area important for controlling fine movements (e.g. moving a finger, wiggling a toe) ❑ Each area of primary motor cortex controls a different part of the body; larger part controls areas involving precision (e.g. tongue, fingers). Continued…  Frontal Lobe ❑ Prefrontal cortex ▪ Anterior (forward) sections of frontal lobe; ▪ Responsible for higher-level cognitive functioning; ▪ Important for memory of what has just happened & what we plan to do next; ▪ Critical for directing attention; ▪ Participates heavily in decision making. ❑ 2 frontal lobes; each lobe controls the operations on opposite sides of the body: ▪ Left frontal lobe – most dominant lobe; works predominantly with language, logical thinking & analytical reasoning. ▪ Right frontal lobe – most associated with non-verbal abilities, creativity, imagination, musical & art skills. 2 Hemispheres & Their Connections ❑ Each hemisphere of the brain: ▪ Gets sensory input mostly from the opposite side of the body. ▪ Controls muscles on the opposite side. ❑ Left hemisphere – specialized for language. ❑ Right hemisphere – important for understanding spatial relationships & for interpreting emotional expressions. ❑ Both hemispheres constantly exchange information: ▪ E.g. If you feel something with the left hand & something else with the right, you can tell if they’re made of the same material. ▪ Reason: the hemispheres pass information back & forth through the corpus callosum. Continued…  2 Hemispheres & Their Connections ❑ Corpus callosum = a large set of nerve fibers that connect the left & right hemispheres of the cerebral cortex. ❑ Corpus callosum allows: ▪ Both hemispheres to convey information + communicate with each other. ▪ For information being processed on one side of the brain to be shared with the other side. ❑ Hence, if the corpus callosum is damaged, both hemispheres can’t share information with one another. Additional Video Reference https://www.youtube.com/watch?v=RpXQnCw2RnI Measuring Brain Activity ❑ Electroencephalograph (EEG) = Device that measures & amplifies tiny electrical changes on the scalp that reflect brain activity. ❑ Magnetoencephalograph (MEG) = Also for measuring brain activity; this device records magnetic changes. ❑ Both methods provide data on a millisecond-by-millisecond basis, measuring the brain’s reactions to lights, sounds, & other events. ❑ However, because they record from the surface of the scalp, they provide little precision about the location of the activity. Measuring Brain Activity ❑ Positron-emission tomography (PET) = device that records radioactivity of various brain areas emitted from injected chemicals. ❑ Red shows areas of most increased activity during some task; yellow shows areas of next most increased activity. ❑ Functional magnetic resonance imaging (fMRI) = procedure that uses magnetic detectors outside the head to compare the amounts of hemoglobin (protein inside red blood cells) with & without oxygen in different brain areas. ❑ Brain MRI help doctors look for conditions (i.e. bleeding, swelling, tumors, infections, damage from injury, stroke, problems with blood vessels). ❑ MRI also can help doctors look for causes of headaches/seizures.  Subcortical Areas ❑ Subcortical areas = areas under the cerebral cortex; it ends at where the spinal cord enters the brain. Thalamus ❑ Heavily involved in relaying (transmit) information between cortex & brain stem. ❑ Like a switchboard – from here sensory information is being directed to different parts of cortex for further processing. ❑ Surrounding the thalamus are areas called the limbic system. Continued…  Subcortical Areas Limbic System ❑ Consists of a number of structures: ▪ Amygdala – process of emotions & memories associated with fear. ▪ Hippocampus – important for memory. ▪ Hypothalamus Hypothalamus ❑ Located just below thalamus; ❑ Important for hunger, thirst, temperature regulation, sex, & other motivated behaviors. Continued…  Subcortical Areas ❑ Cerebral cortex doesn’t directly control the muscles. ❑ It sends output to the: ▪ Pons – brain area that controls certain muscles of the head. ▪ Medulla – brain area that controls some muscles of the head, some sensations from head & output to stomach & intestines. ▪ Spinal cord Spinal Cord ❑ Structure that controls the muscles from the neck down. ❑ Controls many reflexes, such as the knee-jerk reflex. ❑ Reflex = rapid, automatic response to a stimulus; e.g. quickly jerking your hand away from something hot. Continued…  Subcortical Areas Cerebellum ❑ Part of the hindbrain; primarily involved in coordinating movement & balance. ❑ Also plays a role in cognitive functions (e.g. language & attention). Autonomic Nervous System ❑ Autonomic nervous system = section of the nervous system that controls the organs; closely associated with spinal cord, controls the heart, digestive system & other organs. ❑ The term autonomic = involuntary/automatic; e.g. we can’t decide to increase our heart rate the same way that we could decide to wave our hands. ❑ 2 parts of autonomic nervous systems: i. Sympathetic nervous system – activates the fight/flight response during a threat/perceived danger. ii. Parasympathetic nervous system – restores the body to a state of calm. Continued…  Autonomic Nervous System Sympathetic Nervous System Parasympathetic Nervous System Involved in maintaining homeostasis (balance in Involved in the fight/flight response. body system) & permits rest & digest response. Prepares the body for any potential danger. Aims to bring the body to a state of calm. Has shorter neuron pathways hence a faster Has comparatively longer neuron pathways hence response time. a slower response time. Increases heartbeat, muscles tense up. Reduces heartbeat, muscles relaxes. Pupil dilates to let in more light. Pupil contracts. Saliva secretion is inhibited. Saliva secretion increases & digestion increases. In “fight & flight” situations, adrenaline is released by adrenal glands; more glycogen is converted to No such functions exist in “fight or flight” situations. glucose.  Endocrine System Endocrine System ❑ Made up of several organs called glands. ❑ These glands (located all over the body) create & secrete (release) hormones. ❑ Hormones = chemicals that coordinate different functions in the body by carrying messages through blood organs, skin, muscles & other tissues. ❑ These signals tell the body what to do & when to do it. Continued…  Endocrine System Endocrine System ❑ Some hormonal effects are brief: ▪ E.g. changes in heart rate/blood pressure. ❑ Other hormonal effects: ▪ Prepare animals for pregnancy, migration, hibernation/other long-lasting activities. ❑ Within the brain, hormones produce temporary changes in excitability of cells; also influence the survival, growth & connections of cells. ❑ Sex hormones [androgens (male) & estrogens (female)] have strong effects during early development: ▪ Produce differences between male & female anatomies + certain brain areas as well as the rest of the body.  Brain Plasticity ❑ When we talk about brain anatomy, it’s easy to get the impression that the structures are fixed. ❑ In fact, brain structure shows considerable plasticity. ❑ Plasticity = change as a result of experience. ❑ Experiences can alter brain connections; prolonged unusual experiences, e.g. musicians who practice many hours a day change the brain in profound ways.  Brain Plasticity https://www.youtube.com/watch?v=ELpfYCZa87 g  Genetic Principles ❑ Except for red blood cells, all cells contain a nucleus that includes strands of hereditary material called chromosomes. ❑ Chromosomes = threadlike structures made of protein & a single molecule of DNA which carry genomic information. ❑ Each cell = 23 pairs (46) of chromosomes, except ovum & sperm cells (23 each, unpaired chromosomes). ❑ At fertilization – 23 chromosomes from ovum + 23 chromosome from sperm cell form 23 pairs for the new person. Continued…  Genetic Principles ❑ Gene = inherited structures that control the chemical reactions that direct development. ❑ Example: Gene influence height, hair color. ❑ To explain the concept of genes, let’s look at the eye color: ▪ If you have either 1 or 2 genes for brown eyes brown eyes. ✔ Reason: brown-eye gene is dominant; 1 copy of the gene is enough to produce its effect. ▪ If you have 2 genes for blue eyes only will have blue eyes. ✔ Reason: blue-eye gene is recessive; its effects appear only if the dominant gene is absent. Continued…  Sex Chromosomes ❑ Autosome (1st – 22nd pair) = any chromosome not considered as a sex chromosome; associated with various metabolic functions of cell except for sex determination. ❑ Sex chromosome (23rd pair) = either of a pair of chromosomes that determine whether a person is male/female. ❑ Mammals’ sex chromosomes are known as X & Y: ▪ X chromosome – females have 2 per cell; males have 1. ▪ Y chromosome – males have 1 per cell; females have none. ❑ Mother contributes an X chromosome to each child; father contributes either an X chromosome or a Y chromosome. Estimating Heritability in Humans ❑ Heritability = an estimate of the variance within a population that is due to heredity. ❑ Researchers estimate heritability by comparing monozygotic & dizygotic twins: ▪ Monozygotic twins = (“one-egg” twins) twins developed from the same fertilized egg (zygote) have identical genes. ▪ Dizygotic twins = twins who develop from two eggs share only half their genes. Continued… Estimating Heritability in Humans ❑ Researchers examined about 100 pairs of twins (monozygotic & dizygotic) – reared separately & reunited as adults. ❑ On average, monozygotic twins resembled each other more strongly in these aspects: ▪ Hobbies ▪ Vocational interests ▪ Answers on personality tests ▪ Tendency to trust other people ▪ Job/life satisfaction ▪ Probability of mental illness ▪ Consumption of coffee and fruit juices ▪ Preference for awakening early in the morning/staying up late at night ❑ The implication is that genes influence a wide variety of behaviours. Studies of Adopted Children ❑ Another kind of evidence for heritability comes from studies of adopted children: ▪ Resemblance to adopting parents implies environmental influence. ▪ Resemblance to biological parents implies genetic influence. ❑ However, the results are sometimes hard to interpret; example: ▪ Evidence of many adopted children with arrest records had biological mothers with a criminal history. ▪ This could indicate genetic influence, but mothers also provided the prenatal environment (many mothers with criminal records smoked, drank alcohol, perhaps used other drugs) endangered fetus’ brain development. ❑ Prenatal environment is an important influence on development. How Genes Affect Behaviour ❑ Genes affect behaviors by altering the chemistry of the brain. ▪ Example: genetic influence number of taste buds on tongue people’s food preferences. ❑ Genes exert indirect effects by influencing other organs that in turn influence behavior. ▪ Example: dietary choices – almost all infants can digest lactose (sugar in milk). Within a few years, nearly all Asian children & many others lose the ability to digest it; loss depends on genes, not on how often people drink milk. ❑ Genes also influence behaviours by altering body anatomy. ▪ Example: Genes unusually good-looking many people smile at you, invite you to parties, try to become your friend increased self-confidence & social skills. The Multiplier Effect ❑ Multiplier Effect = a small initial advantage in some behaviour, possibly genetic in origin, alters the environment & magnifies that advantage. ❑ What started as a small natural advantage greater & greater – as a result of environmental influences + genetics. ❑ Example: ▪ Genes made a person tall + help develop fast running skills. ▪ Tall + fast running skills natural advantage in basketball playing (compared to others of the same age) get into basketball teams. ▪ Get into basketball team receive coaching skills improve. ▪ Skills improve experience more success + receive further encouragement. Environmental Modification of Genetic Effects ❑ Phenylketonuria (PKU) = an inherited disorder that increases the levels of a substance called phenylalanine in the blood. ❑ Phenylalanine = a building block of proteins (amino acid) that is obtained through diet. ❑ PKU gene is recessive; meaning a person must have TWO genes to genetically inherit PKU. ❑ If untreated, PKU mental retardation; phenylalanine can build up to toxic levels in blood & other tissues. ❑ Nerve cells in brain are particularly sensitive to phenylalanine levels. ❑ Excessive amounts of phenylalanine cause brain damage. Continued… Environmental Modification of Genetic Effects ❑ Phenylalanine – found in most protein-containing foods; e.g. milk, eggs, cheese, nuts, soybeans, chicken, beef, beans & fish. ❑ People with PKU can’t metabolize (breakdown) phenylalanine. ❑ On ordinary diet, an affected child accumulates phenylalanine in the brain becomes mentally retarded. ❑ Thus, a special diet with low phenylalanine is required to protect the brain. ❑ Fact: about 2% of people with European/Asian ancestry & almost no Africans have the recessive gene that leads to PKU. Evolutionary Psychology ❑ Evolution = gradual change in frequency of various genes from one generation to the next. ❑ However, some aspects of human behaviuor make no sense except in the context of evolution; examples: ▪ Goose bumps (when we’re cold) – they don’t do anything for humans today (our body hairs are short, usually covered with clothing); but for other mammals with hairier skin, goose bumps helps erect their hairs when they’re cold extra insulation in cold environment (useful for ancient ancestors). ▪ Baby’s grasp reflex – infant’s hand tightly grasps anything placed into the palm; serves no function today, but for our ancient ancestors, it helped infants hold onto the mother as she travelled.