Biology of Mind Essay

Custom Student Mr. Teacher ENG 1001-04 14 November 2016

Biology of Mind

* Everything psychological is simultaneously biological  * Plato correctly located the mind in the spherical head * Aristotle believed mind was in the heart  * Although heart is the symbol for love, psychology has proven that you fall in love using your brain * 1800s Franz Gall (German psychologist) invented phrenology theory that claims that bumps on our skull could reveal our mental ability and character traits * Biological Psychology – the branch of psychology concerned with the links between biology and behaviour * Biological psychologists sometimes called Behavioural neuroscientist, neuropsychologist, behaviour geneticist, psychological psychologist, bio psychologist …

* We are a system of substances, that are composed of even smaller substances (tiny cells make up body organs) * Body’s information system is built from billions of tiny interconnected system of neurones * Sensory Neurones – neurons that carry incoming information from the sensory receptor the brain and the spinal cord for processing – “afferent” * Motor Neurons – the neurons that carry outgoing information from the brain to the muscles and the glands – “efferent” * Interneurons – neurons within the brain and the spinal corf that that communicate internally and intervene between the sensory inputs and the motor outputs * Each neuron consists of a:

* Cell body and branching fibres (the cell’s life support center) * Dendrite fibres – receive information and conduct it toward the cell body * Axon – passes messages away from the cell body to other neurons, muscles and glands * Can be very long projecting several feet into the body * Myelin sheath – a layer of fatty tissue segmentally encasing the fibres of many neurons * Allows for fast impulse transmission among neurons * If myelin sheath degenerates, communication to muscles slow with eventual loss of muscle control * Action potential – brief electric charge that travels down a neuron’s axon (neural impulse) * Generally an axon is in a negative state, while the fluid outside an axon is in a positive state * Resting potential – the positive outside/ negative inside state of an inert neuron * K+ [ ] in axon < Na+ [ ] outside axon (-70mv)

* Axon membrane is Selectively Permeable – does not allow everything inside (selective) * When a neuron fires, the first bit of the axon opens up allowing positively charged sodium ions to enter * That section of the ion becomes depolarized, making the axon’s next channel to open up * During resting period(refractory period) the neurons pump the positively charged sodium ions back outside * Each neuron receives signals from hundreds of other neurons * Excitatory signals – like pushing a neuron accelerator * Inhibitory signals – like pushing its breaks

* Threshold – the level of stimulation required to trigger a natural impulse * If the excitatory signal minus inhibitory signal exceeds a min intensity (-60mv) * How neurons communicate: Before thought that axon of one cell fused with dendrites of another, but Sir Charles Sherrington noticed that it takes a long time for the signal to travel. Therefore concluded that there is a gap * Synapse – the junction between the axon tip of the sending neuron and the dendrite of the receiving cell * Synapse gap (synaptic cleft) – the tiny gap at the junction (less than a millionth inch wide) * When action potential reaches the terminal’s at the axon, release of chemical messenger is triggered (neurotransmitters) * Soon the neurotransmitters cross the synapse gap and bind to the receptor site on the receiving neuron * For an instant the receptors unlock the channels at the receiving site and electrically changed atoms flow in , exciting or inhibiting the receiving neuron readiness to fire * Then reuptake occurs (a process when the sending neuron reabsorbs the neurotransmitters)

* How neurotransmitters Influence Us : there is a particular path way in the brain for certain neurotransmitters and particular neurotransmitters may have particular effect on behaviour and emotion * Example: Acetylcholine (ACh) – one of the best understood neurotransmitters * Has to do with learning and memory

* At every junction between motor neurons and skeletal muscles * Muscles contract, but when pathway is blocked we are paralyzed * Drugs like artificial opiates (like heroin and morphine) lessen pain and boost mood, may cause brain to stop producing its natural opiates (may cause discomfort) * Drugs and other chemical affect brain chemistry at synapses by either amplifying or blocking a neurotransmitter’s activity * Agonist – a molecule similar to a neurotransmitter that can mimic its effect or block the reuptake * Black widow spider venom floods synapses with Ach cause muscle contractions … and possibly death * Antagonists – block neurotransmitter’s functioning * May occupy receptor sites – but not similar enough to stimulate receptor

* Nervous system – body’s electrochemical communication network consisting of nerve cells from peripheral and central nervous systems * Peripheral Nervous System (PNS) – sensory and motor nervous system that connects the CNS to the rest of the body. Has 2 components: * Somatic Nervous System – part of the PNS that controls skeletal muscles * Automatic Nervous System – part of the PNS that controls the glands and muscles of the internal organs (ie the heart) * Sympathetic nervous System – arouses the body and gives energy * Accelerate heartbeat, raise blood pressure, slow digestion … when something alarms, enrages or challenges you making you alert and ready for action * Parasympathetic Nervous System – calms the body down, conserving energy (opposite of sympathetic) The two work together to keep you in steady internal state

* Central Nervous System (CNS) – the brain and the spinal cord * Neural networks– groups of brain neurons cluster into work groups * Neurons network with near-by neurons with which they can make fast connection * Spinal cord – information way connecting PNS to the Brain * Reflex – an automatic response to a sensory stimulus – spinal cord’s work * Simple reflex pathway is composed of single sensory & motor neurons * Communicate through interneurons

* Below pt of injury on spinal cord – loses connection w/ brain – lose all sensation and voluntary movement in body regions with sensory & motor connections * The Endocrine System – body’s slow chemical communication system; a set of glands that produce hormones into your bloodstream * Hormones – chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream and affect other tissues * Slower than neural massages, but last longer

* Adrenal Gland – a pair of endocrine glands that sit just above the kidneys and secrete hormones (epinephrine and norepinephrine) that help arouse the body at time of stress * Increase heart rate, blood sugar levels, blood pressure … * Pituitary Gland – endocrine system’s most influential gland. When under hypothalamus influence, the pituitary gland regulates growth and controls other endocrine glands * Pea sized structure located in the core of the brain * Example pituitary gland influences the sex glands to release sex hormones * (brain pituitary other hormone brain ) – connection b/w endocrine + nervous

Module 5

* Lesion – tissue destruction  * Brain lesion -Naturally or experimentally caused destruction of brain tissue * Used in Experiments: tiny clusters of normal/defective brain cells would be destroyed w/ surrounding unharmed – which part influences what Scientists electrically/chemically/magnetically stimulate various parts of the brain – note effects * Neuroscientists study the working brain by: recording brain’s electrical activity * Electroencephalogram (EEG) – amplified recording of the waves of electrical activity that sweep across the brain’s surface (measured by electrodes places on scalp) * PET (positron emission tomography) Scan – visual display that shows brain activity that detects where radioactive glucose (gamma rays) goes in the brain while it performs a certain task * Active neurons are glucose hogs

* MRI (magnetic resonance imaging) – technique that uses magnetic field and radio waves to produce computer generated images of the soft tissue – show brain anatomy * Align spinning atoms of the brain molecules, then radio wave pulse temporarily disorients atoms return to normal spin; formed detailed pic of the brain tissue b/c released signals * fMRI (functional MRI) – a technique revealing blood flow (brain activity), by comparing successive MRIs – show brain function and structure

* Brainstem – the oldest part of the central core of the brain * Starts where the spinal cord swells as it enters the skull * Responsible for automatic survival functions  * Medulla – base of brainstem * Responsible for heartbeat and breathing * Right above the medulla are the pons help coordinate movement Brainstem is where most nerves to and from each side of the brain connects to the opposite side of the body – crossover pt * Reticular formation – located inside brainstem b/w ears – extends from spinal cord thalamus * A nerve network – plays an important role in controlling arousal * Filters incoming stimuli and relays important info to other parts of brain * Thalamus – brain’s sensory switchboard receives sensory info – except smell – from all senses, then directs messages to the sensory receiving area in the cortex and transmits replies to the cerebellum and medulla * Located on top of the brainstem

* Cerebellum – functions include processing sensory input and coordinating voluntary movement output and balance – located at the back of the brainstem * Enables nonverbal learning + memory – judge time, modulate emotions, discriminate sounds/textures Limbic System – neural system associated with emotions and drive * Located below cerebral hemisphere – 2 halves of brain (brain hemisphere) * Hippocampus – process memory

* Amygdala – two neural clusters linked to emotion (influences aggression and fear) * Hypothalamus – located below the thalamus – keep body’s internal environment in a steady state * Directs several maintenance activities (eating, drinking, body temperature) * Helps govern endocrine system via pituitary glands

* Linked to emotions and reward

Module 6

* Older brain networks sustain basic functions and enable emotion, memory and basic derives * Newer brain networks (within the cerebrum the two hemispheres that make up 85% of our brain mass) are responsible for more advanced things like speaking and thinking and perceiving Cerebral cortex – thin layer of interconnected neural cells covers the brain(cerebral) hemispheres. – body’s ultimate control + info-processing center (thinking mostly occurs) * As we move up the animal ladder, cerebral cortex expands, genetic control decreases, and adaptation increases * small cerebral cortex (ie frogs) operate mostly on programed genetic instructions (instinct); larger cortex – larger capacity for learning & thinking more adaptable * Humans have a very complex functioning cortex

Structure: Has lots of wrinkles and if expanded, triples the area * brain hemispheres filled w/ axons connecting cerebral cortex to all other brain regions * Glial cells – cells in the nervous system that protect, nourish and support neurons * Provide nutrients, insulating myelin, guide neural connection and mop up ions and neurotransmitters to neurons * May also participate in information transmission and memory * Moving up animal chain proportion of glial cells to neurons increases * Each hemispheres (there are 2) are divided into 4 lobes separated by fissures (folds) * Frontal lobe (behind the forehead) – involved in speaking and muscle movement also controls making plans and judgments * Parietal lobe (at the top to rear) – receives sensory input for touch & body position * Occipital lobe (at the back of the head) – receives information from visual fields * Temporal lobe (above the ear) – includes auditory areas (receives info from opposite ear) Functions:

* German physician Gustav Fritsch and Eduard Hitzing applied mild electric stimulation to a dog’s cortex caused parts of the dog’s body to move * Worked only when stimulating the arch shaped regions on the back of the frontal lobe * Stimulating parts of this region in the left/right hemisphere caused movements on opposite side of certain body parts Motor cortex – area at the rear of the frontal lobe that controls voluntary movement * Areas of body that require most control (like fingers and mouth) have largest area * Sensory cortex – area at front of parietal lobe that process sensory touch &movement sensations * The more sensitive the body region, the larger area for sensory cortex is developed for it * Association area – areas of the cerebral cortex not involved in primary motor control function or sensory functions: they are involved in more complex functions like learning, memory, thinking and speaking * Not dormant areas – rather interpret, integrate & act on info processed by sensory areas * found in all four lobes

* Front lobe enable judging, processing of new memories and planning * Damage to frontal lobe may cause personality change (Ex Gage, damaged frontal lobe, but still had all memories and skills intact.. just became more irritable and dishonest) * Parietal lobe enable mathematical and three-dimensional reasoning * Underside of the right temporal lobe allows us to recognize faces * Memory, language & attention results from synchronized activity among brain areas * Brain’s Plasticity – brain’s ability to change, during childhood, by reorganizing after damage or building new paths based on experience * Severed neurons do not regenerate and some specific brain functions are reassigned to certain areas * Some neural tissue can be reorganized if the person is still young * Constraint-induced therapy – aims to rewire the brain by warning a fully functioning limb and forcing the used of the disfunctioning limb * Losing a finger may cause the sensory area responsible for that finger to input adjacent figures (making them more sensitive) * Neurogenesis – formation of new neurons

* The fact that brain`s two sides serve different functions is seen when there is damage * 1961, Philip Vogel and Joseph Bogen thought that major epileptic seizures were caused by increase in brain activity bouncing back and forth between the cerebral hemispheres * Tried cutting the corpus callosum – the large band of axon fibre connecting the two brain hemispheres and carrying massages between them * Split brain – condition resulting from the surgery that isolates the brain`s two hemispheres by cutting the fibres (mainly those in corpus callosum) connecting them * Normal personality and intellect hardly affected * Right hemisphere – used when a person preforms perceptual tasks * Makes inferences to languages

* Left hemisphere – increase activity when a person speaks or calculates * Makes quick, literal interpretations of language * Also responsible for sign language in deaf people

* 90% of people are right handed and 10% of people are left handed ( a bit more male left handed people and a bit less female) * 96% of right handed people process speech in left hemisphere * 70% of left handed people process speech in left hemisphere, and everyone else either left or both * Bias of right hand is unique to humans (and other primates like chimpanzees and baboons) * Either genes or parental factor indicates handedness

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