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Biological Foundations of Behaviour Midterm 1 Notes

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Patrick Davidson

Biological Foundations of Behaviour January 10, 2014 Terminology • Neuroscience • Biopsychology / Psychobiology / Behavioural Neuroscience o Physiological Psychology (recording brain activity, system level) o Neuropsychology (effect of brain lesions on behaviour) o Comparative/Evolutionary (bio-) psychology Implicitly Assumed Model? • An interconnection between psychology & biology etc. PSYCHOLOGY BIOLOGY Philosophical Influences CHEMISTRY • Evolution of Analogies About Mind/Brain PHYSICS o Greeks - basic physics o 17 Century - pumps o Industrial Revolution - great machine o 1960s - computer * usually still use this vie/theory o Today – Quantum physics o (Ancient China, India & Egypt – trephination) The Greeks • Greeks proposed idea of mind (spirit-self) o Divided into components: sensation, memory, reasoning o On different plane, separate from physical self • Socrates & Plato o Dualism: mind & body are separate o Nativism: knowledge is innate • Aristotle o Monism: mind & body are connected o Empiricism: knowledge comes from experience • Dualism o Definition: mind separate from body, different realm from physical world o Mind-Body problem  How do the mind and body interact?  Where? Brain? Heart? Blood? • The Greeks on Abnormal Behaviour o Somatogenic – from physical cause o Psychogenic – from mental cause  Psychogenic/dissociative amnesia • Hippocrates o One of 1 to suggest somatogenic causes of abnormal behaviour o Dysfunction of body leads to dysfunction of thought & action. o Believed that psychopathology was the result of body's humours.  Blood (moodiness/passion)  Black bile (melancholy)  Yellow bile (irritability & anxiousness)  Phlegm (dullness, sluggishness) o Suggested that epilepsy caused by problems in brain, suggested that brain is seat of mind Renaissance • 1300s to 1600s • “Rebirth” in arts and sciences • Thinkers often crossed disciplines, studied various topics • Relevant advances o Basic physics (Kepler, Newton) o Basic anatomy (Leonardo, Vesalius) o Visual artistic techniques (Leonardo, others) o Mechanistic systems • Rene Descartes -1600s o “Cogito ergo sum" = I think, therefore I am o Animal Human difference = soul o All animal behaviour therefore reflexive  Also much of human behaviour o Controlled by brain, nerves o Soul & brain interact - pineal gland. • Descartes on Mind-Body Interaction: o Mechanistic Explanation of Reflexes:  Energy from fine causes mechanical signal to brain (via thread) o Brain opens value to a conduit leading to muscle o Resulting fluid pressure expands muscle, allowing its withdrawal • Materialism o Thomas Hobbes  Broke from dualism by rejecting soul  Mind generated through operation of body (brain): Materialism  Mind is product of sensory experience: Empiricism • Mind is blank slate • "Tabula Rasa"  Contrast to nativism (mind & mental faculties innate, inborn)  Nature vs. Nurture Philosophical Approaches to Mind • Advantages: o Clear thinking, based on “first principles” (assumptions) and clear logic following from them o No resources required (money, lab, research, participants) • Disadvantages: o What if first principles are wrong? o Dispassionate, carefully collected, repeated observations, can often help settle arguments Biological Influences • Effects of different drugs/substances on mind/body • Ancient Egypt: o Descriptions of effects of brain injuries • Ancient Greece: o Rudimentary brain surgery (trephination) o Description of many sensory nerves (feeding into brain) o Hippocrates:  Epilepsy is brain disease  Brain is seat of mind • Knowledge of anatomy came before knowledge of physiology o Anatomy = structure o Physiology = function • Leonardo da Vinci o Careful drawings based on cadavers o Used wax to make impression of ventricles • 1700s & 1800s o Galvani:  Nerves, muscles function through electricity (1791) o Localization of function  Different areas do different things o Helmholtz:  Speed of electrical transmission in nerve (not instantaneous) • Weber: o Magnitude of sensory perceptions  Data followed orderly (physical) laws  Origin of psychophysics • Scientific Revolution: Basic Tenets 1. Mind follows rules same as material world 2. Mind can be measured and quantified 3. One person’s mind (and brain) works similarly to another’s • Detour: Phrenology o Basic assumptions still a line today o "Highbrow" / “Lowbrow" o Florenz used ablation/lesion to test hypothesis o Idea is right, map was wrong Evidence from human lesions o Broca's patient "Tan" (reported 1861)  Could only say "tan”  Other faculties appeared intact (Basic Tennet 2)  Other cases found (Basic Tennet 3) o Language function in left frontal lobe th th • 19 & 20 Century Explosion in Knowledge January 15, 2014 Evolutionary Bases • Charles Darwin – Biological origins of ALL animals o Theory of evolution implied direct link between man and nature o Natural selection of physical as well as behavioural traits o Theory is incompatible with idea that humans are "special" • Perspectives on Brain and Behaviour Darwin’s Concept of Natural Selection: o Explanation for how new species evolve and existing species change over time o Differential success in the reproduction of different characteristics (phenotypes) results from the interaction of organisms with their environment o Biological level simpler o Psychology trait (personality) more complicated/controversial o Implications of Natural Selection:  Because all animal species are related, their neurons & 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 • Lot of similarities in structure & function but are different o Top/outside - fairly different o Level down - Limbic system - fairly similar o Ponds - greater similarity Differences Between Species • Gross anatomy often sufficient • As time/species developed, brain size increased Evolution of the Human Brain Brain Size and Behaviour • Principle of Proper Mass: o Species exhibiting more complex behaviours will possess relatively larger brains • Developed an index of brain size to allow comparisons among different species o Used body size to predict brain size • Heavier, more dense brain = more complex behaviours o Weight of brain relative to weight of body • Many animals have cerebral cortex (part of brain with most sophisticated behaviour) but humans have a lot of folding Why the Hominid Brain Enlarged 1. The Primate Lifestyle • The foraging behaviour of primates is more complex than other animals o Finding fruit is more difficult than eating grass or other vegetation on the ground:  Sensory  Conceptual  Spatial  Memory  Social-Strategic (Co-operative competition)  Teaching/Learning – culture 2. Changes in Hominid Physiology • Radiator Hypothesis o The more active the brain is, the more heat it generates 3. Neoteny • Rate of maturation is slowed o Allows more brain cells to be produced • Adults retain some infant characteristics • Newly evolved species resemble the young of their common ancestors o Human heads look more like the heads of juvenile chimpanzees than adult chimpanzees Studying Brain and Behaviour in Modern Humans • Evolutionary Approach o Acceptable to compare brain & behaviour between species BUT difficult to compare within species! Brain Size & Intelligence • How does one measure brain size? o Control for skull thickness o Volume vs. weight o Control for body weight  Can fluctuate within an individual over time o Effect of age, physical health, brain damage? • How does one measure intelligence? o What cognitive/behavioural skills do you count as intelligent? o People vary enormously in their individual abilities, depending on the task • Are people with larger brains more intelligent? o Brain size and intelligence do not seem to be particularly 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  Gross brain size doesn't correlate o If gross brain size does not seem to correlate with intelligence, what explains the difference in abilities among individuals?  Relative size of certain brain regions?  Relative function of certain brain regions?  Synaptic density? Is more dense better? Animal Studies • Humans appear to be exceptionally encephalized • Humans have certain faculties that are much more sophisticated than other animals’ • Converse: humans have certain faculties that are much LESS sophisticated than other animals’ • This is a course relating biology to HUMAN behaviour (rather than zoology) • Certain biological and psychological functions should be preserved across species, especially close relatives • There is less disagreement about how to treat humans than animals (meaning we simply refuse to allow some procedures on humans) • The cost of not learning about neurological diseases is high: o Material cost (health care, productivity etc.) o Human (suffering) • Animal Research: o Must:  Be approved by a quasi-independent research board, which includes community members  Have plausible chance of advancing science, to benefit humans, animals, or environment  Be necessary (cannot be done any other way)  Use minimum number of subjects (statistical power)  Use most human methods, and follow optimal standards for health and care 10 Principles Of Nervous System Function 1. Principle 1 • The nervous system’s function is to produce action/movement within the perceptual world created by the brain • The sequence of processing is: o “In" -> Integrate -> "Out" (Sensory) (Behaviour) • At cellular level (affect neurons have on neighbouring neurons) o Nuclei level o Brain level 2. Principle 2 • The Details of Nervous-System Functioning are Constantly Changing, an Attribute called Neuroplasticity o Learning o Experience o Recovery of function 3. Principle 3 • Many Brain’s Circuits are crossed (Right side processed by Left Hemisphere) 4. Principle 4 • The Central Nervous System Functions on multiple levels o “Descent with Modification"  During evolution, new brain areas were placed on top of older ones • Newer brain levels added increased control and processing • Levels work together to produce behaviour 5. Principle 5 • Brain is both Symmetrical & Asymmetrical o Asymmetry is essential for certain tasks:  Language is usually on the left side  Spatial functions are usually on the right side 6. Principle 6 • Brain systems are organized both Hierarchically & in Parallel o Splits and feedback contributes to sophisticated behaviour o Binding Problem: Because a single sensory event is analyzed by multiple parallel channels that do not converge onto a single brain region, there is said to be a problem in binding together the segregated analyses into a single sensory experience 7. Principle 7 • Sensory & Motor Divisions exist throughout the Nervous System o Sensory and Motor divisions in the Somatic Nervous System o Sensory and Motor divisions in the Central Nervous System 8. Principle 8 • Sensory Input to the Brain is divided for Object Recognition and Motor Control o Example: Dorsal and ventral processing streams in the visual system 9. Principle 9 • Functions in the Brain are both Localized and Distributed o Because functions (e.g. language) have many aspects, it is note surprising that these aspects reside in widely separated areas of the brain o Small area of damage = focal symptoms o Large area of damage = remove entire function 10.Principle 10 • The Nervous System works by juxtaposing excitation and inhibition o Excitation: process by which the activity of a neuron is increased o Inhibition: process by which the activity of a neuron is decreased or stopped o Applies to individual neurons and to nuclei o Not the same as mental/behavioural excitation or inhibition Anatomy and Functions • How many neurons in the brain? o Human brain: 100 billion o Octopus brain: 300 million o Honey bee brain: 950,000 o Aplysia nervous system: 18,000-20,000 How Does The Nervous System Function? Overview of Brain Function and Structure • The Brain’s Primary Functions: 1. Creating a sensory reality: There are more motor parts of the brain 2. Integrating Information: There are parts of the brain very sophisticated 3. Producing Behaviour • Peripheral Nervous System: Somatic and Autonomic Systems: Sympathetic and Parasympathetic Divisions. • Central Nervous System: Brain and Spinal Cord • Everything happening in the brain can be happening microscopically but if you pull the lens back the individual neurons are working together. With a cellular perspective you cannot forget the system perspective. Molar/Systems Level • Orientation within the brain: o Dorsal: above or referred to as rostral superior o Posterior: Tail, caudal o Medial: Middle o Lateral: Side o Anterior: front or frontal or o Ventral: Below, belly, inferior • Slices of the Brain: o Has new terminology: Coronal, Horizontal, Sagittal • Afferent Nerve: carries information from sensory receptors in skin to the brain • Efferent Nerve: carries information from the brain to the neurons controlling leg muscle, causing a response. Surface Features: • 5 layers: o Skull o Dura mater o Arachnoid layer o Pia mater o Subarachoid space (filled with CSF) o o Brain Internal Features • White Matter: o Areas of the nervous system rich in fat-sheathed neural axons. o Connecting bundles usually sending information from one center to anther and receiving it back. • Gray Matter: o Areas of the nervous system predominately composed of cells bodies and blood vessels • Ventricle: o A cavity in the brain that contains cerebrospinal fluid (CSF) o 4 in total Tour of Anatomy Organization of the Nervous System The Central Nervous System • Brainstem o Hindbrain:  Evolutionarily the oldest part of the brain  Contains: • Cerebellum • Reticular Formation • Pons • Medulla  Important for the Control of Movement o Cerebellum:  Controls complex movements and has a role in a variety of cognitive functions, as well  May support memory, understanding, using numbers, and self control  Size of cerebellum increases with the physical speed and dexterity of a species o Reticular Formation:  Netlike mixture of neurons (gray matter) and nerve fibers (white matter)  “Reticular Activating System”  Stimulates the forebrain: • Regulation of sleep-wake behaviour and behavioural arousal o Pons:  “Bridge”  Connects cerebellum to the rest of the brain  Controls important movements of the body o Medulla:  Rostral end of the brain  Vital functions: • Control of breathing and heart rate • Midbrain o Tectum:  Roof of midbrain  Important for: • Sensory processing (visual and auditory) • Produces orienting move
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