PSY2301 - Andra Smith PDF

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PSY2301: BIOLOGICAL FOUNDATIONS OF BEHAVIOURChapter 1 - OriginsWhy Study Brain and Behaviour? - Many behavioral disorders can be explained and possibly cured by understanding the brain - The brain is the most complex living organ on Earth - How the brain produces both behavior and human consciousnes...

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PSY2301: BIOLOGICAL FOUNDATIONS OF BEHAVIOUR Chapter 1 - Origins Why Study Brain and Behaviour? • Many behavioral disorders can be explained and possibly cured by understanding the brain • The brain is the most complex living organ on Earth • How the brain produces both behavior and human consciousness is a major unanswered scientific question • What is the Brain? • Cerebral Cortex • Heavily folded outer layer of brain tissue composed of neurons (cortex = “bark”) • Gyri: bumps on the folded surface • 1.3 kg of an organ that has gyri • Sulci: grooves of the cortex • Gyri and sulci help us identify what part of the brain we’re talking about. • Gross Structure of the Nervous System • Central Nervous System (CNS) • The brain and spinal cord • Spinal Cord: Part of the CNS encased within the vertebrae or spinal column • Spinal cord gets info to the brain from the rest of the body • Peripheral Nervous System (PNS) • All the neurons in the body located outside the CNS • pns has an autonomic and somatic system; somatic more related to muscles and sensations we have and autonomic is things we aren’t consciously aware of (ie. reading). • What we have in our peripheral system are nerves, in the brain it’s neurons. • Neuron • A brain cell engaged in information processing • Sensory Neuron • Neuron that carries incoming information from sensory receptors into the spinal cord and brain

ie. if I stick my hand on top of a hot stove top, the sensory neurons send info to the brain and tell you to take your hand off through the motor neurons. • Motor Neuron • Neuron that carries information from the spinal cord and brain to make muscles contract • 100 billions of neurons that help us create our behaviour What is Behaviour? • Irenäus Eibl-Eibesfeldt: • “behaviour consists of patterns in time.” • Wrote Love & Hate, father of ethology (study of animal behavior) from Vienna • Examples • Movements, vocalizations, thinking, memory • Julien Offroy de la Mettrie argued that thought was produced by the brain. • Got a fever, was forced to quit his position because he said this in a period where everyone believed everything was controlled by God • Damnatio memoriae; the damnation of memory (he must not be remembered), was erased from history • Innate behaviours • ‘Patterns in time’ that are relatively fixed, invariant ways of responding • Ie. kittens attack birds even when they aren’t hungry • Learned behaviours • Flexible ways of responding • Ie. baby learning to take a bottle • Complexity of behaviour varies considerably in different species • Simple nervous system  narrow range of behaviour • Complex nervous system  wider range of behaviour • neural structure becomes much more advanced when behaviours are much more complex. •

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History of Brain Research: Perspectives on Brain and Behaviour • Mentalism o An explanation of behaviour as a function of the nonmaterial mind o Ancient Greece: Aristotle  Brain cooled the blood; no role in producing behaviour  Psyche: Synonym for mind; an entity once proposed to be the source of human behavior (if we don’t have a psyche we don’t exist) • Dualism o A nonmaterial mind and the material body contribute to behaviour o “The mind and body must be joined and united to constitute people”

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o Mind-Body Problem  Quandary of explaining a nonmaterial mind in command of a material body (dualism) o Rene Descartes  Mind directs rational behaviour  Body and brain direct all other behaviour via mechanical and physical principles  Examples: sensation, movement, and digestion  Mind is located in the pineal gland of the brain, which sits beside ventricles filled with fluid  Believed ventricles that have CBSF is controlled by the pineal gland which cause the muscles to move; this is obviously wrong.  Mind regulates behaviour by directing the flow of ventricular fluid to appropriate muscles o Problems with Descartes  Pineal gland is involved in biological rhythms, but not in intelligence or behavioural control  Fluid is not pumped from the ventricles to control movement  Questions  Are they separate entities working together or separate? o Penfield  neurosurgeon in Montreal who did surgery on patients with epilepsy and was able to map some of the functions of the brain (ie. motor cortex and language areas)  Died in the 70s and was a pioneer in neuroscience in mapping the brain  Relevant because even though he’s a neurosurgeon, he argued that he was probably a dualist. Materialism o Behaviour can be explained as a function of the nervous system without explanatory recourse to the mind o Supported evolutionary theories of Alfred Wallace and Charles Darwin  Both were struck by the many similarities among species o Darwin’s Concept of Natural Selection  Explanation for how new species evolve and existing species change over time  Differential success in the reproduction of different characteristics (phenotypes) results from the interaction of organisms with their environment o How are traits selected naturally  1. Genetic Mutation  2. Adaptive Trait  3. Increases Chances of Survival

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4. Trait Passed on to Offspring  If the vegetation changes, if theres a drought, then theres an adaptation that passes along to enhance survival so they can create offspring o Implications of Natural Selection  Because all animal species are related, their neurons and their brains must be related, too  Rationale for studying simpler animals to understand humans  Because all species of animals are related, their behaviour must be related, too  Emotional expressions in humans (across cultures) and other animals are similar  Both the brain and behaviour changed bit by bit in animals that evolved to greater complexity, as humans obviously did Evolution of Brain and Behaviour • Can trace our lineage by comparing the genes, brains, and behaviours of different animals (ie. in 2015, there was a new set of bones found = new species) • Origin of Brain Cells and Brains • Despite the age of the Earth (4.5 billion years), brain cells and brains are quite recent adaptations • First forms of life: 3.5 billion years ago • First brain cells: 700 million years ago • First brain: 250 million years ago • First human-like brain: 3 - 4 million years ago • Modern brain: 100,000 - 200,000 years ago • Animals with Nervous Systems

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Among the various animal categories, the nervous system has evolved considerably o Nerve net: simplified sensory neurons and motor neurons o Segmented nerve trunk: complexity of movement o Ganglia: collection of the nerve cells together o Chordates: ganglia gets much more complex

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Chordate Nervous System o Nervous systems vary widely among chordates, but all are/have:  Bilaterally symmetrical and segmented  Brain and spinal cord encased in cartilage/bone

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Crossed organization: Each hemisphere receives information from and controls the opposite side of the body  Spinal cord is dorsal (at the back) to the heart and gut o Behavioural complexity among chordates is correlated with the evolution of cerebral hemispheres and cerebellum:  Cerebellum: located in the hindbrain; involved in the coordination of motor and other mental processes  Increased size and more convolutions (increases the volume of the cerebral cortex)  The larger the cerebellum, more motor activity you can coordinate

Human Evolution: Members of the Primate Order • Features common to primates: o Excellent color vision o Eyes in front of face: enhance depth perception o Females: Usually only one infant per pregnancy; infants require more care o Larger brains • We’re chordates but also primates

Brain Size and Behaviour • Jerison (1973) o Principle of Proper Mass: Species exhibiting more complex behaviours will possess relatively larger brains o Developed an index of brain size to allow comparisons among different species  Used body size to predict brain size This chart is body weight vs. brain weight - The homo sapiens are at the farthest level, meaning they have the largest relative brain size to body weight - As body weight increases, so does the brain, but at 2/3s of the body weight

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Ie. porpoises have big brains, yet relative to body size humans are larger and more density •

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Encephalization Quotient (EQ) o Measure of brain size obtained from the ratio of actual brain size to the expected brain size for an animal of a particular body size H. sapiens have the largest EQ

Enlarging Hominid Brain • Relative size of the hominid brain has increased nearly threefold – Australopithecus afarensis (smallest) – Homo erectus (center) – Modern Homo sapiens (largest) • Rapid climate changes have been thought to produce new environments that select for new traits (e.g., larger brains); adaptation to environmental challenges • Example: – Animals that walked upright would do well in grass-covered areas that were not previously covered with grass • 1. The Primate Lifestyle – The foraging behaviour of primates is more complex than other animals • Finding fruit is more difficult than eating grass or other vegetation on the ground • Need good sensory, spatial, and memory skills • Fruit eaters have larger brains • 2. Changes in Hominid Physiology – Radiator Hypothesis (Falk, 1990) – The more active the brain is, the more heat it generates – Increased blood circulation  improved brain cooling  enabled size of hominid brains to increase – Stedman (2004) • Genetic mutation  smaller facial muscles and bones  change in diet  increased brain size • In other words, intro of meat and protein into diet made brain bigger Studying Brain and Behaviour in Modern Humans • Evolutionary Approach – Make brain-behaviour comparisons between different species • CAUTION:

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– Difficult to make brain-behaviour comparisons between members within the same species • Example: Brain size and intelligence Are people with larger brains more intelligent? – Problems with answering this question: How does one measure brain size? – Control for skull thickness – Volume versus weight – Control for body weight – Can fluctuate within an individual over time – Effect of age, physical health, brain damage? How does one measure intelligence? – People vary enormously in their individual abilities, depending on the task – Ie. Person A is good at math and bad at spatial abilities, vice versa for B In other words, brain size and intelligence are not related. – Research has shown that many smart people (e.g., Einstein) have average size brains – Women’s brains weigh about 10% less than men, but the two sexes do not differ in measures of average intelligence If gross brain size does not seem to correlate with intelligence, what explains the difference in abilities among individuals? – Relative size and function of certain brain regions? Culture: – Learned behaviours that are passed on from one generation to the next through teaching and learning Brain is highly flexible: – We perform many tasks today that our brains were not originally selected for early during evolution • Example: programming computers

Ch. 2 - NS Function & Structure The Brain’s Primary Functions 1. Creating a Sensory Reality a. Evolution has equipped each species with a view of the world that helps it survive i. Ie. dogs have better smell than humnas, humans see colours better 2. Integrating information a. Current knowledge can be compared with past knowledge i. To create knowledge that integrates information from different times and sensory domains and then use that knowledge to guide behaviour 3. Producing Behaviour a. Example: Movement

To and From the Brain  To the brain: Afferent  From the Brain: Efferent

Summary • Top: dorsal or superior • Bottom: ventral or inferior • Front: anterior or rostral • Back: posterior or caudal • Middle: medial • Side: lateral • Afferent: information to the brain • Efferent: information from the brain Overview of Brain Function and Structure: Surface Features  Meninges: three layers of protective tissue o 1. Dura: (hard) Tough double layer of Fibrous tissue enclosing the brain in kind of loose sack  Bottom picture

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o 2. Arachnoid: thin sheet of delicate connective tissue that follows the brain’s contours o 3. Pia Matter: (soft) moderately tough membrane of connective tissue fibers that cling to the surface of the brain Meningitis o Caused by infections in the meninges (particularly in the pia matter and the arachnoid layer, and the CSF between them) o Can result in swelling of the brain o Sx include: headaches, cervical rigidity, drowsiness, stupor, coma  NOTE: there is a difference between meningitis and encephalitis. The latter refers to an infection to the brain itself Cerebrospinal Fluid (CSF) o Sodium chloride and other salts o Fills the ventricles and circulates around the brain and spinal cord in the subarachnoid space (located between the arachnoid layer and the pia mater) o Cushions the brain o Meningitis: Infection of the meninges and CSF Folded Tissue o Gyri: outer of the folds o Sulci: inner of the folds o Increases SA so can fit more material in  Thick unfolded vs. folded paper in a cup Cerebral Cortex o Outer layer of the brain  Near occipital lobe  there is a gap  Central sulcus  only sulcus that goes across the whole brain  Good landmark to identify all the gyri you have

Brainstem o Central structures of the brain, including the hindbrain, midbrain, and diencephalon

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Surface Blood Vessels o Anterior, middle, and posterior cerebral arteries o Stroke:  Sudden appearance of neurological symptoms as a result of severe interruption of blood flow

Major Arteries  Brain Irrigation o Three major arteries  Anterior cerebral artery  Middle cerebral artery  Posterior cerebral artery  Stroke o A sudden disruption of blood flow to the brain o The nature of deficit depends on the site affected o 2 major types of stroke  Hemorrhagic (20% of strokes)  Ischemic (80% of strokes)  Embolic (embolus) a clot formed outside the brain  Thrombotic (thrombus) a clot formed inside the brain

Internal Features

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White Matter – Areas of the NS rich in fat-sheathed neural axons • The axons of the neurons myelin sheath largest is corpus collosum Gray Matter – Areas of the nervous system predominately composed of cell bodies and blood vessels • Mainly cell bodies and blood vessels Ventricle – A cavity in the brain that contains cerebrospinal fluid (CSF) – Four ventricles • Two lateral ventricles (left and right) • Third ventricle • Fourth ventricle Corpus Callosum – Fiber system connecting the two cerebral hemispheres

Microscopic Inspection  Two main types of cells: o Neurons  Carry out the brain’s major functions o Glia  Aid and modulate neurons’ activities  Nucleus (pl. nuclei) o A group of cells forming a cluster that can be identified with special stains to form a functional grouping  Nerve o Large collection of axons coursing together outside the central nervous system  Tract o Large collection of axons coursing together inside the central nervous system Evolutionary Development

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Human brain is a complex mammalian brain, yet it still retains most of the features of other less complex mammalian brains • Our brain has added to reptilian and mammalian brain • Occipital helps us to see, but many other areas that help process visual stimuli • 1:12 ratio of brain part to behaviour Most behaviours are not the product of a single locus in the brain, but rather of many brain areas and levels Evolution of refinement of behavior is the refinement of the nervous system.  Adaptation added on more neuronal connection.  Hence we do see many similarities between vertebrates, and more developed brains as these structures were added on.  The behavior was able to get more complex and refined. Evolution has not discarded any region of the brain.

The Central Nervous System • The Spinal Cord – Controls most body movements – Can act independently of the brain • Spinal reflex: – Automatic movement – Hard to prevent (brain cannot inhibit) – Example: Knee-jerk reflex • The Brainstem • Begins where spinal cord enters the skull • Produces movement and creates a sensory world • Three regions: – Hindbrain – Midbrain – Diencephalon Hindbrain • Evolutionarily the oldest part of the brain • Integrates both voluntary and involuntary body movement • Contains: – Cerebellum – Reticular Formation

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– Pons – Medulla Control of movement

– Cerebellum – Controls complex movements and has a role in a variety of cognitive functions (ie. balance) – Subcortical: just below the cortex – A little brain of its own – impulsivity which is considered to be a PFC behaviour gets input from cerebellum – Size of cerebellum increases with the physical speed and dexterity of a species – Reticular Formation – Netlike mixture of neurons (gray matter) and nerve fibers (white matter) – “Reticular activating system” • a lot of different nuclei in the hindbrain – Stimulates the forebrain: • Regulation of sleep-wake behaviour and behavioural arousal • Pons (“bridge”) – Connects cerebellum to the rest of the brain – Controls important movements of the body • Medulla – Rostral end of brain – Vital functions: • Control of breathing and heart rate Midbrain • Tectum (roof of midbrain) – Sensory processing (visual and auditory) – Produces orienting movements • Tegmentum (floor of midbrain) – Eye and limb movements – Species-specific behaviours – Perception of pain • ventral tegmental area (big part of the tegmentum is where dopamine is produced • Vital part of our dopamine source • Tectum is on the dorsal side, tegmentum is on the ventral side – Tegmentum = motor output of what the tectum brings in – Ones for visual processing info and one is for audio processing info Diencephalon: integrates sensory and motor information on its way to the cerebral cortex

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– Made up of the hypothalamus and thalamus – Takes in sensory input (they all do and create motor output) – As we get higher in the brain, we get more complicated processing Hypothalamus – Very small, only about .3 percent of brain volume, regulates homeostatic functions • The kingpin that exists in our endocrine system • Stress response is produced because the hypothalamus allows it, then turns it off when you’re done the exam – Feeding – Sexual behaviour – Sleeping – Temperature regulation – Emotional behaviour – Hormone function • Through connections with the pituitary gland Thalamus – 20 different nuclei, a center relay system – Brings in all sensory input and sends that info to the rest of the cortex – Also contributes to other types of processing • Sensory processing • Motor processing • Integrative functions • Motivation • Memory ie. lateral geniculate nucleus part of our visual pathway that takes in information, whereas the medial one takes auditory – Example of how auditory and visual info is kept separate (organized) – Thalamus is large, hypothalamus is just below it

The Forebrain 3 Structures • Neocortex: – Regulates various mental activities • Newer brain part – Cerebral cortex (same thing) • .5-4 mm thick – 6 layers of gray matter – Creates and responds to a perceptual world • Basal Ganglia: – Control of movement • Group of nuclei – Caudate nucleus, putamen, globus pallidus • Limbic System:

– Regulates emotions and behaviours that create and require memory • Related to memory and motivation – Does have layers of GM but fewer and less complex and much older than the neocortex layers The Neocortex/cortex  Four Lobes o Occipital: Vision o Parietal: Tactile o Temporal: Visual, auditory, and gustatory o Frontal: Integrates sensory and motor functions; planning  all speak to each other (one doesn’t function separately)  Layers o Di...