Week 3-Parts of the Brain and Neurotransmitters
Week 3-Parts of the Brain and Neurotransmitters PSYS 001
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This 11 page Class Notes was uploaded by Adele on Thursday February 4, 2016. The Class Notes belongs to PSYS 001 at University of Vermont taught by Rudiger in Winter 2016. Since its upload, it has received 50 views. For similar materials see Intro to Psychological Science in Psychlogy at University of Vermont.
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Date Created: 02/04/16
Notes from the Acrobatiq Platform Unit 4: Brains, Bodies, and Behavior Module 5: Neurons: The Building Block of the Nervous System Neurons are Specialized Cells Designed for Communication Neuron-cell within the nervous system that receives and transmits info o Nervous system contains around 100 billion neurons Neurons are composed of three major parts o Soma-cell body which contains nucleus and keeps cell alive o Dendrite-collects info from other cells and sends said info to the soma Made up of a branching fiber o Axon-transmits info away from soma to neurons/muscles/glands Made up of a long and segmented fiber Each is specialized Often surrounded by a myelin sheath Myelin sheath is a fatty tissue later that functions as a insulator and increases the speed of electrical signal transmission At the end of each axon is a terminal button o If signal reaches terminal buttons they are signaled to give out chemicals known as neurotransmitters o Synapses-spaces between neurons Neurons Communicate Using Electrochemical Processes Electrical signals in neurons move due to changes in electrical charges within the axon Resting potential-the state the axon is normally in o Where interior of neuron has a larger number of negatively charged ions than the area outside the cell When part of axon that is closest to body cell is stimulated by electric signal from dendrites + this signal is strong enough to pass a certain threshold then the cell membrane opens and allows sodium ions with positive charges to enter. Once this happens then positive charges between greater than negative charges. o The electrical change described is called action potential Axon is segmented by breaks/gaps, each of which is called a node of Ranvier o As each segment passes on impulse, one behind goes back to negative resting potential o Axon potential=all or nothing. Therefore neurons can more energy by increasing sped but cannot fire more strongly. Also cannot fire repeatedly due to a refractory period-brief time when cannot fire again because has not returned to resting potential Neurotransmitters: The Body’s Chemical Messengers Synapses allows axon to communicate with many dendrites in neighboring cells Neurotransmitter-chemical that relays signals between neurons via synapses o Travel between terminal button of one neuron to dendrites of others Their release is triggered when the electrical impulse from the action potential reaches then end of the axon. Receptor sites and neurotransmitters are specialized to recognize each other o May cause either excitatory or inhibitory Neurotransmitters that are not accepted have to be removed from synapse in order to the next stimulation to occur o Occurs partially via enzyme breakdown and partially via reuptake (neurotransmitters in synapse are reabsorbed into transmitting terminal buttons) Drugs: o Agonist-binds to receptor sites in dendrites to excite neuron (acting like neurotransmitter) Ex. Cocaine o Antagonist-reduces or stops normal effects of neurotransmitters. Binds to receptor sites and blocks it. Major Neurotransmitters o Acetylcholine (ACh)-used in spinal cord and motor neurons to stimulate muscle contractions Also used by the brain to regulate dreaming, memory and sleeping o Dopamine-involved in learning, makes feeling of pleasure in brain’s reward system, involved in motivation, emotion, and movement o Endorphins-natural pain relievers. Released as a response to orgasm, eating spicy food and vigorous exercise o GABA (gamma-aminobutyric acid)-major inhibitory neurotransmitter in brain o Glutamate-most common neurotransmitter (release in 90% of brain;s synapses) o Serotonin-many functionsmood, sleep, aggression and appetite Module 6: Brain Regions The Old Brain: Wired for Survival old brain (innermost structures)-regulates survival functions- moving, breathing, feeding, emotion, resting cerebral cortex-outer layer of brain that humans have brain stem-oldest/innermost regions o controls most basic functions of life such as attention, motor responses and breathing o begins where spinal cord enters the skull and forms the medulla which is the area of the brain stem that controls breathing and heart rate o spherical shape about the medulla is called the pons which helps in controlling the body’s movements (mostly walking and balance). Also plays a bit roll in dreaming, waking, sleep and arousal o The reticular formation is a network of neurons that runs through the pons and medulla. Its job is to filter out some stimuli that =coming into the brain from spinal cord and to pass on the other info to other areas of the brain Plays big role in eating, walking, sexual activity and sleeping. attention and alertness o Thalamus-sits about brain stem (egg shaped) Filters more of sensory info coming from spinal cord + reticular formation. Passes on remaining signals to higher brain levels Also receives some of the replies and passes them to the cerebellum and the medulla. Helps in sleep as shuts off incoming signals from senses o Cerebellum Coordinates voluntary movement Has two wrinkled ovals behind brain stem The Limbic System Brain stem’s primary function is to regulate the most basic aspects of life Limbic system’s primary function is responsibility for emotions and memory o System of brain structures around and beneath the thalamus Include: amygdala, hypothalamus, hippocampus and others Pituitary gland is controlled by the limbic system Amygdala-made up of two almond-shaped clusters o Primarily responsible for reactions to/perception of aggression and fear o Connected to sympathetic nervous system, processing of smell, facial response and release of neurotransmitters that are related to aggression and fear. Hypothalamus-under thalamus o Helps regulate hunger, thirst, body temperature, sex drive, response to satisfaction of all the above needs by creating feelings of pleasure Hippocampus-has to horn-shaped structures that curve away from the amygdala o Helps store info in LTM The Cerebral Cortex Intelligence cannot be measured by ration of brain weight to body weight Human intelligence can be attributed to the fact that we have larger cerebral cortexes. o Cerebral cortex is a outer layer that is barklike and allows humans to use language, create tools, live in social groups and acquire complex skills. It is about 1/10 of an inch think but makes up 80% of brain’s weight. o Humans have a folded cerebral cortex, which gives it a greater surface area and increased capacity for remembering, thinking and learning. This folding is called corticalization. o Glial cells-support neurons, Link to neurons/surround them, protect them, absorb unused neurotransmitters and provide neurons with nutrients Come in many different forms-ex. Myelin sheath is a kind of glial cell o Cerebral cortex is divided into two hemisphere(left and right), each hemisphere into four lobes (temporal, frontal, occipital and parietal) , each of which is separated by folds (called fissures) frontal lobe-behind the forehead primary responsibility is for planning, thinking, judgment and memory houses motor cortex parietal lobe-middle to back of skull primary responsibility is processing info about touch occipital lobe-back of skull primary responsibility is processing visual info temporal lobe-in front occipital lobe (~between ears) primarily responsibility is for language and hearing Functions of the Cortex o Contralateral control-brain is wired so that (a majority of the time) one hemisphere of the brain controls and receives signals from the opposite side of the body o Motor cortex-runs across top of the brain from ear to ear in frontal lobe. Controls and executes movements of the body by sending signals to cerebellum and spinal cord Sends messages to specific parts of the body and the somatosensory cortex receives messages from the different parts of the body. It is right behind the motor cortex in the front of the parietal lobe. For both, the most complex/sensitive the regions controlled, the more space is allotted to it in the cortex o Visual cortex- in occipital lobe. Processes visual info o Auditory cortex-within the temporal lobe(which also processes visual info that allows us to name objects) Responsible for language and hearing o the rest of the cortex is made up of areas where motor and sensory info is combined with stored knowledge Random note: brain has no sensory receptors Neuroplasticity, Neurogenesis, and Brain Lateralization Neuroplasticity –brain’s ability to change structure and function in order to adapt to experience and/or damage o Most plastic when young Neurogenesis-formation of new neurons o These new neurons form deep in the brain and then can later migrate Brain lateralization-left and right hemisphere are specialized to perform different functions Corpus callosum-connects two hemispheres of the brain Results of split brain experiment o left hemisphere houses ability to write, speak and understand languages. Also better with math, time and rhythm. Also better at coordinating complex movements o right hemisphere is better at perceptual things such as puzzle, draw, faces, melodies and patterns Module 7: Methods for Studying the Brain Cadaver and Lesion Studies cadaver o benefit-can study entire brain o drawback-brain no longer active/alive o lesions-damages in brain caused by various things (rarely by surgery) lesion studies: allow to study loss of brain function that may occur. Used to study damaged part of brain to determine functioning utility o a lot of social decision-making abilities originate in frontal lobe now often use nonintrusive imaging Noninvasive Techniques noninvasive techniques o lesion studies=done using neuroimaging o single-unit recording method-thin microelectrode is surgically inserted in or near an individual neuron (mostly used with animals) records electrical response/activity in specific neuron o EEG (electroencephalograph)-instrument that records electrical activity produced by brain’s neurons via electrodes placed on surface of person’s head. Looks at brain waves Benefits: person can move around Does not provide clear photo of structure of brain o PET scan (positron emission tomography scan) Invasive imagining technique that provides colour- coded of brain activity by tracking brain’s use of radioactively tagged compound (glucose, oxygen, injected drug) Person lays in scanner and completes mental task o fMRI (Functional magnetic resonance imaging) type of brain scan that uses magnetic field to form images of brain activity in different areas of the brain detects amount of blood flow in each brain region (more oxygen needed shows more activity) noninvasive Transcranial Magnetic Stimulation transcranial magnetic stimulation (TMS) o magnetic pulses are applied to the brian of living people with goal of safely/temporarily deactivating a small region of the brain electrical stimulus=applied before or during a task, effects are assessed. Main benefit: allows person to draw causal conclusions concerning influence of brain structures on thoughts/feelings/behaviors Module 8: The Nervous System and the Endocrine System The Central Nervous System Central nervous system (CNS) o Involves the brain and spinal cord o Main controller of body’s functions o Receives signal, processes it, and responds it o Nerves are differentiated according to their function Sensory neuron-carries info from sensory receptors Motor neuron transmits info to muscles and glands Interneuron-most common types of neuron. Responsible for communicating among neurons. allows the brain to combine multiple sources o Spinal cord-long, thin, tubular bundle of nerves and supporting cells that extend down from the brain. When quick response is needed, brain can be bypassed and cord takes care of everything on its own o Reflex-involuntary and nearly instantaneous movement in response to a stimulus Triggered when sensory information is powerful enough to reach a certain threshold and interneurons in spinal cord act without the brain, sending info through motor neurons The Peripheral Nervous System Peripheral nervous system (PNS)-links CNS to body’s sense receptors, muscles, and glands o Divided into two subsystems-one controls internal responses and the other external responses Autonomic nervous system (ANS)-the one that govern the internal activities of human body-heart rate, breathing, salivation, digestion, urination, perspiration and sexual arousal. This system can also be divided into two parts Sympathetic division of the Ans-preparing the body for rapid action in response to stress from threats or emergencies by activating organs + glands in the endocrine system. Bodies entire changes=fight or flight response. Parasympathetic division of the ANS-tends to calm body by slowing heart, breathing and allowing body to recover from reactions triggered by the sympathetic system. Works slower than the sympathetic system but eventually returns the body to homeostasis. Somatic nervous system (SNS)-control external aspects of the body-skin, skeletal muscles, and sense organs The Endocrine System Primary function of sympathetic and parasympathetic nervous systems=to interact with the endocrine system-secretes chemical messengers called hormones that influence emotions and behaviors. System=made up of glands(groups of cells that secrete hormones into the bloodstream). System works closely with the nervous system Secretion of hormones=regulated by the hypothalamus o Main link between nervous system and endocrine system o Directs release of hormones by interactions with the pituitary Pituitary-controls body’s growth but also has other influences o Controls ovulation/menstrual cycle o Influence response to pain o Influences hormones that signal ovaries/testes to make sex hormones Pancreas-secretes hormones that are designed to keep the body supplied with fuel so at to be able to produce and maintain energy stores Pineal gland-in middle of brain o Secretes melatonin-helps the wake-sleep cycle Adrenal glands-located on top of each kidney. Triangular in shape. o Produce hormones that regulate salt/water balance. o Involved in metabolism, sexual development/function and the immune system o Secrete epinephrine (adrenaline) and norepinephrine Lecture Notes (little bit on memory but mostly brain structure) Desirable Difficulties o Vary conditions o Distribute(no massing) o Interleave SUBJECTS (not topics) About 45 min then switch o Test yourself o Don’t drop flashcards too soon o Don’t permanently drop flashcards o Get comfortable with being ignorant Why people choke under pressure (specific to test taking anxiety) o What helps: write about worst fears about ten min before test o The trouble comes from the stress of wasting energy trying not to think about anxiety caused by the exam during the exam Research hypothesis and variables o Hypothesis: a precise statement about presumed relationships btwn specific parts of a theory Another definition: a specific and falsifiable prediction about relationships btwn/among two variables o Variables: attribute that can assume different values btwn people/tings across different times or places Occam’s Razor o When two competing theories make exactly the same predications, the simpler one is preferred o Idea of parsimony Statistical Significance o Difference btwn groups o Quantitative means of evaluating the research hypothesis o P=probability that the observed pattern is due to random variation/chance o P –value threshold (meaning is not due to chance) is less than or equal to .05 Inhibitory neurotransmitters o Decrease likelihood neuron will fire Excitatory neurotransmitters o Increase likelihood will fire Exogenous Substance o Agonist-chemically similar, mimics effects of a neurotransmitter o Antagonist-reduces/blocks effects of a neurotransmitter Neurotransmitters o Acetylcholine-muscle contractions, memory, sleep, dreaming Associated with Alzheimer’s o Dopamine-emotion, reward with learning, movement, motivation Elevated levels associated with schizophrenia Deficit associated with Parkinsons o GABA-inhibitory transmitter Low associated with anxiety and can caused involuntary motor actions o Serotonin-mood, sleep, appetite, aggression Low levels are associated with depression o Endorphins-natural pain killers Released with exercise, orgasm and spicy foods Brain stem: o Thalamus-relay between brainstem and rest of brain All senses except smell Sleep/wakefulness o Reticular Formation o Pons Hearing Balance Taste Touch Pain(especially in the face) o Medulla Respiration Heart rate Lobes: Frontal, Temporal, Parietal, Occipital Hemisphere: o left: language, math, judging time and rhythm, sequencing complex movement o right: perceptual skills, recognizing objects and faces, recognizing patterns and melodies, drawing pictures human brain o deeper something is in the brain-the more basic function it tends to have output: motor cortex input: somatosensory cortex neuroplasticity-brain’s ability to change its structure and function in response to experience or damage reflexes: behavior that occurs without brain; happens in spinal cord
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