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Biological Bases of Behavior AP PSYCHOLOGY UNIT III Historical Perspectives The idea of the “mind” has been around since Plato Franz Gall, a German physician, believed that bumps on a persons head could be used to determine their personality and mental abilities Right idea, wrong format We know now that the brain has specialized areas Biological psychology: the scientific study of the links between biological and psychological processes Micro to Macro Biological psychology is best understood from the smallest parts to the biggest parts We know that all parts of us are made of cells Nerve cells allow communication within the body Individual cells make organs, organs make systems, systems work together for us to live There are specific systems in the brain with specific functions A quick aside: There is A LOT of vocabulary in this unit. Expect a vocabulary quiz daily. Neurons & Neural Communication The building block of the nervous system is the neuron, or nerve cell Other “Parts” of the Neuron Nodes of Ranvier: the spaces between the myelin sheath; essential for allowing the message to travel quickly down the axon Terminal Buttons: ends of the terminal branch of the axon; release the chemicals into the synapse Synapse: presynaptic neuron buttons, synapse, and postsynaptic neuron dendrites Synaptic cleft: space between neurons where chemicals are released and absorbed by the next neuron to continue the action potential Action Potential The action potential is the process by which a message is transported down a neuron When the neuron is not firing, it is at resting potential The neuron is relatively negative on the inside and positive on the outside There is more K+ on the inside, more Na+ on the outside The ion channels are selectively permeable K+ will flow slowly in and out, but Na+ only enters when the sodium channels are open In order for a neuron to fire, it needs to reach a minimum threshold Each neuron has 2 types of messages being sent to it at the same time: inhibitory & excitatory If there are more excitatory, it will send the message Na+ channels open and it enters the neuron, making the inside more positive K+ channels open and it leaves the neuron to return the inside to a negative charge All-or-none response – a neuron either sends the message or it doesn’t Applies to a single message…we interpret a difference between a light tap and a slap because there are more messages being sent at the same time Refractory period – the period of time after a neuron sends a message when it cannot send another message The action potential is a lot like flushing a toilet, if you think about it. Explain how… Neurotransmitters (NTs) NTs are chemical messengers released from the axon of one neuron to cross the synaptic cleft and bind to receptor sites on the dendrites of the next neuron Reuptake: when the sending neuron reabsorbs any NTs left in the cleft How NTs Work & NTs to Know NTs effect specific behaviors and emotions, sometimes individually, other times in concert with another NT Particular brain pathways may use only 1or 2 NTs Two types of NTs & Drugs Agonist: stimulate a response Antagonist: inhibit or block a response Drugs work by either acting as an agonist or antagonist Opiates increase feelings of arousal Botulin blocks ACh release and paralyze muscles Top NTs to Know (Table 9.1) Acetylcholine (Ach) Dopamine Serotonin Norepinepherine GABA Glutamate Endorphins Nervous System The Nervous System is the body’s communication network made up of all of the nerve cells in the central & peripheral nervous systems Nerve: bundle of axons 2 main divisions of the nervous system Central Nervous System (CNS): brain & spinal cord Peripheral Nervous System (PNS): sensory and motor neurons that connect the CNS to the rest of the body Interneuron: neurons within the brain & spinal cord that communicate internally and between the sensory inputs and motor outputs NERVOUS SYSTEM CENTRAL NERVOUS SYSTEM PERIPHERAL NERVOUS SYSTEM Central Nervous System BRAIN SPINAL CORD Where our thoughts, behaviors, & emotions originate from Connects the brain to the PNS and vice versa Made up of 40-86 Billion neurons, 400 Trillion synapses Reflexes—automatic responses to stimuli Neuron clusters organize into neural networks—connecting with nearby neurons to create quick, short connections Experiences strengthen these connections…that’s why practice is important Go through the spinal cord…a single sensory neuron sends info to the spinal cord, which activates a motor neuron to send the response Allows your body to react before your brain has time to process what is going on Neural Chain, aka Reflex Arc The brain processes the sensory info and decides what to do Sensory information enters the body through receptor cells Motor neurons receive commands from the brain and react NERVOUS SYSTEM CENTRAL NERVOUS SYSTEM BRAIN SPINAL CORD PERIPHERAL NERVOUS SYSTEM Peripheral Nervous System SOMATIC NS AUTONOMIC NS Voluntary control of skeletal muscle movements Controls glands and muscles of the internal organs Almost everything you do is controlled by this branch Controls breathing, heart rate, digestion Some activities can be consciously overridden (slowing your breathing rate) Broken into 2 subsystems Talking Walking Writing Sympathetic Parasympathetic NERVOUS SYSTEM CENTRAL NERVOUS SYSTEM BRAIN SPINAL CORD PERIPHERAL NERVOUS SYSTEM SOMATIC NERVOUS SYSTEM AUTONOMIC NERVOUS SYSTEM Autonomic Nervous System Sympathetic Nervous System: alerts body to an emergency Parasympathetic Nervous System: calms body after an emergency Organs work under both sympathetic & parasympathetic Eyes: pupils dilate (sympathetic) & contract (parasympathetic) Stomach: inhibits digestion (sympathetic) & stimulates digestion (parasympathetic) Bladder: relaxes (sympathetic) & contracts (parasympathetic) Sound File NERVOUS SYSTEM CENTRAL NERVOUS SYSTEM BRAIN SPINAL CORD PERIPHERAL NERVOUS SYSTEM SOMATIC NERVOUS SYSTEM AUTONOMIC NERVOUS SYSTEM SYMPATHETIC NERVOUS SYSTEM PARASYMPATHETIC NERVOUS SYSTEM Endocrine System Body’s slow communication system; glands that secrete hormones into the bloodstream Hormones: chemical messengers created by endocrine glands Endocrine glands Pituitary – “master gland” that influences release of hormones by other glands; releases growth hormone & oxytocin (giving birth & breastfeeding) – controlled by hypothalamus Adrenal – pair of glands that secrete epinephrine (adrenaline) & norepinephrine, which help arouse the body in times of stress Works with sympathetic NS to initiate fight-or-flight Thyroid – metabolism Pancreas – regulates blood sugar Brain Scanning Techniques We can’t look into your brain and see your thoughts or emotions, but we can see what your brain is doing when you have thoughts and experience emotions Lesions: destroyed brain tissue; naturally or experimentally caused Electroencephalogram (EEG): amplified recording of energy waves across the brain’s surface Computed Tomography (CT) Scan: x-rays taken from a variety of angles and combined into a composite representation of a slice the brain Positron Emission Tomography (PET) Scan: shows brain area’s consumption of glucose, which occurs when an area is active; person is given a task and we can see what part of the brain is used to complete it Magnetic Resonance Imaging (MRI): using magnetic fields and radio waves to produce images of the brain; shows us the parts Head is put into a strong magnetic field, then radio waves disorient the atoms in the brain When the atoms return to their normal spin they emit signals that provide detailed pictures Funtional MRI (fMRI): shows structure and function of brain by showing bloodflow Look at MRIs taken seconds apart to see changes when completing a task or looking at a picture Brain Scans Older Brain Structures Structures of the brain that control base needs: breathing, sleeping, feeding Brainstem: oldest part of the brain, starts at the top of the spinal cord, made up of the medulla & pons. Medulla: base of the brainstem; controls heartbeat & breathing Pons: controls movement People in a vegetative state have damage above the brainstem-they can still breathe, their heart pumps, but other faculties have been lost Mike the Headless Chicken Also the nerve crossover point that allows the right hemisphere to control the left side of the body and vice versa Thalamus: pair of egg-shaped structures that sit on top of the brainstem; act as your sensory relay station taking information from every sense except smell and routing it to the appropriate part of the brain. Reticular Formation: netlike nerve network that goes from the spinal cord through the thalamus. Filters some of the sensory information going to the thalamus and sends it on to other brain areas. Also plays a role in arousal. Cerebellum: at rear of the brainstem, split in two, it looks like a minibrain. Has many roles—enables nonverbal learning, memory, helps judge time, & moderate emotions. Coordinates voluntary movement…if you are an athlete, dancer, can drive a car…thank your cerebellum. Limbic System Located between the hemispheres and brainstem. Primarily associated with emotions & drives. Amygdala: two nerve clusters the size of lima beans. Strong link with aggression & fear. Hypothalamus: below thalamus; regulates many bodily functions including hunger, thirst, body temp, sexual behavior. Kluver & Pucy study of rhesus monkey by removing/stimulating amygdala. (Olds, 1975) through accidental placement of an electrode, psychologists discovered that hypothalamus contains a reward center. Rats would continuously press a button that stimulated that part of the brain. They would even run over electrified floors to get to the button. Hippocampus: connected with memory. Cerebral Cortex-Structure The cerebral cortex is the outer layer of the 2 hemispheres of the brain. It is where high-level thinking occurs. Glial cells: cells that support neurons by providing nutrients & myelin, guiding neural connections, and cleaning up ions & NTs. Broken into 2 hemispheres with 4 lobes each Frontal: speaking, muscle movement, judgment, emotions, planning Parietal: behind frontal; receives sensory input for touch & body position Occipital: at back of head; receives info from visual fields Temporal: above ears; primarily the auditory area Cerebral Cortex-Function Motor cortex: strip at back of frontal lobes Controls motor function Mapped out by body part (p. 106); the more precise the control, the larger the area devoted Psychologists & physicians are able to map this out because your brain has no sensory nerves, allowing the patient to remain awake during brain surgery Somatosensory cortex: strip at front of parietal lobes Processes body touch and movement sensations Similar to the motor cortex, each body part has its own spot The more sensitive the body part, the larger the space There are other areas of the brain that deal with sensory information beside touch Association Areas Areas of the cerebral cortex not involved in primary motor or sensory functions Can’t map them like the sensory & motor areas Prefrontal cortex: judgment, planning, processing new memories Parietal lobes: areas believed to be connected to math & spatial reasoning Right temporal lobe: facial recognition (if damaged, you would still recognize facial features, but not who the person is) Broca’s area: speaking Wernicke’s area: understanding language Aphasia Patient Aphasia Patient Plasticity & Other Stuff Plasticity is the brain’s ability to change and reorganize after damage and form new pathways as the result of experiences Some brain functions seem set in location, while others are able to be reorganized Neurons are a different matter-if they are severed, they do not regenerate…if your spine is cut, you will be paralyzed Neurogenesis: formation of new neurons Occurs deep in the brain, then neurons migrate Brain-Computer Interfaces Psychologists have been able to implant electrodes in certain parts of the brain and connect that to a computer that is able to complete a task the person is thinking about…Just think of the applications! Brain Hemispheres The corpus callosum is a bundle of nerves that connects the 2 hemispheres of the brain and facilitates communication. Split brain refers to patients whose corpus callosum has been severed, or in some cases never developed. This procedure is usually performed to stop excessive neural activity and seizures. Psychologists learn a great deal from these patients about the functions of each hemisphere and other specialized areas of the brain. They also help better understand the interesting organization of sensory information coming in through the eye. Man with Split Brain You have probably heard people talk about being “rightbrained” or “left-brained”, but those are inaccurate statements. We all use all of our brain, it’s just that some of us are more specialized in one hemisphere’s skills. Left Hemisphere Right Hemisphere Logical Visual Language centers Artistic Speech Excels at making inferences Consciousness Consciousness is our awareness of ourselves and environment. It is what allows us to “read” our surroundings and survive. It also provides us with long-term vision, so to speak. Without consciousness, we would live only for right now, seeking pleasure, without considering the consequences of our actions. Cognitive neuroscience seeks to study how brain activity is linked to cognition (perception, thinking, memory, language). With scans, psychologists can see that some non-communicative patients brains are stimulated in areas associated with activities they are imagining. Dual Processing Psychologists are discovering that our brain works on two separate tracks, conscious and unconscious, simultaneously. When we see an object in front of us, we consciously identify it (that’s a baseball). At the same time, our brain is processing information about the ball. A lot of what we do occurs below our conscious thought. These unconscious actions and processes allow us to focus our conscious thoughts on more immediate concerns. Behavior Genetics The study of the power and limits of genetics on behavior. In other words, how much effect does your nature have on behavior…Nature vs. Nurture. The human body has 20,000-25,000 genes. Some are active, others are inactive-waiting to be turned on by your environment. As a human race, we are a lot more alike than we are different because of our genetic makeup. Psychologists are looking at the differences between individuals. There isn’t one gene for aggression, many genes come together to influence that trait. Twin & Adoption Studies The single best way to determine the effect of nature and nurture on behavior because you are separating the two. Identical twins are especially important to study because of their genetically identical makeup. Key point: they have the same genes, but not always the same number of genes-that is why one twin might develop a disease the other may not. Fraternal twins also serve as good subjects because while they are no more similar than regular siblings, they are raised at the exact same time period eliminating variables related to the time period a child is raised in. Identical twins separated at birth have been studied since about 1980. There are some examples of separated twins that have led remarkably similar lives, see the “Jim’s” story in your book. What twin studies tell us is that nature and nurture play a pretty even role in our behavior. It’s important to note that a genetic predisposition does not mean a person will develop a disease, certain personality trait, or grow to be exactly 5’10’’. It means that genetic markers indicate it could happen. The other side of separated twin studies is the environment they are raised in. These studies give us a pure look at environmental influences since the children bear zero genetic relationship to their adoptive parents. People who grow up together do not have similar personalities, whether they are genetically related or not. Think about you and your siblings…how much do you have in common with each other? This does not mean that environment does not influence our personality. Adoption does seem to have a positive effect on adopted children. Adopted children tend to score higher on intelligence tests & be more well-adjusted than their bio parents. Molecular Genetics Study of the molecular structure and function of genes Looking at individual genes to see if they can determine who would be predisposed to a certain disease They would look at a family with generational history of bipolar, for example, and take blood samples to look at each person’s DNA What are the ethical implications of knowing this when a woman is pregnant? What types of actions might be taken by someone who’s child has been labeled “at risk for disease x”? Heritability First off, this does not mean inherited! Heritability is the extent to which variation among individuals can be attributed to genetics. Having two eyes has 0 heritability, essentially everyone has 2 eyes. Height or intelligence are highly heritable - diabetes and cancer are less heritable. As environments become more similar, heritability increases. If people had similar genetics but different upbringings, heritability would decrease. Gene-Environment Interaction Our genetics and environments interact to create our personality. Are boys rough and girls gentle because it’s their nature, or does the environment encourage it? Boy v. girl baby Boy v. girl toys Epigenetics is the study of environmental influences on gene expression without DNA changes Agouti Mice Evolutionary Psychology Remember that evolutionary psychology is the study of the evolution of behavior and the mind. Natural selection: inherited trait variations that contribute to reproduction and survival will most likely be passed on. Mutation: random error in gene replication that results in a change. Differences between groups (5%), ie-India vs. Russia, is less than differences within groups (95%) Because of natural selection…those that asked the right questions and stayed alive procreated and created offspring, those that ate the poisonous plants and tried to pet the leopards usually died Today: evolutionary psychology is used to answer many questions Nature-Nurture We are a true combination of both, but neither is totally predetermined. We can choose not to reproduce, we can choose not to go with the crowd. Does our environment shape us, or do we shape our environment? Figure 15.1 Biopsychosocial approach