The Nervous System Friday August 30 2013 8 49 PM Physiological Psychology Behavior Pseudoscience Specialization of Function Phrenology 1800s the whole brain contains the mind The mind has different parts of the brain The idea of specialization proved correct Evidence came from patients with selective brain damage Phineas Gage 1848 worker on the railroad Iron rod entered his skull under his cheek he survived and never lost consciousness during the accident After the injury he suffered profound personality changes he became impulsive and crude Descartes error different functions of the mind and thus different aspects of personality are distributed Parts of the mind are linked to the machine Tan s Brain 1861 patient unable to speak except for tan His brain was damaged in a certain area now called Broca s area Broca s Aphasia difficulty with speech and grammar but understands individual words Wernicke s Aphasia difficulty with meaning but follows grammar Broca s and Wernicke s areas for language Visual cortex receives written words as visual stimulation Transforms visual representations into an auditory code Wernicke s area interprets auditory code Motor Cortex word is pronounced Broca s area controls speech muscle s via the motor cortex Hormones How are messages sent through the body Hormones and neural communication Hormones are one method for sending messages Primitive intercellular communication Hormonal communication endocrine cells secrete chemicals into the blood stream Neurohormone communication The pituitary gland secretes neurohormones into the blood stream that trigger the release of hormones from the adrenal gland Endocrine Glands Adrenal glands helps trigger the fight or flight response Five step process for fight or flight 1 The brain interprets something as scary and signals the hypothalamus 2 The hypothalamus connects to the pituitary gland 3 The pituitary gland releases neurohormones into the bloodstream 4 The adrenal glands secrete hormones into the bloodstream 5 The body reacts to prepare for fight or flight Neural Communication The neuron Cell body Dendrites Axon and axon terminals how messages are passed in and out Axon coated in myelin sheath fat Three types of neurons Sensory Motor Interneurons Sensory and Motor A few million exist in the body Can be up to five feet long Interneurons 100 billion Neurons in the brain connect with one another to form networks After about 15 months of life no new neurons are made just new connections The action potential An electrical impulse that moves down the axon Influences the activity of other cells Is a charge in the permeability of the cell membrane The change in permeability allows charged ions to pass in and out of the cell Action potential begins with resting potential Resting potential the cell is charged with more negative molecules on the inside Why potassium K can move out of the cell through open channels while sodium Na cannot move in 1 Depolarization Sodium channels open allowing sodium Na to move into the cell to balance the electrical force So many rush in that the charge inside cell becomes positive This causes sodium channels further down to open 2 Repolarization The Synapse Neurotransmitters Potassium then flows out to recharge the membrane The sodium and potassium are put back via a process that uses food and O2 from the bloodstream The action potential reaches the axon terminal and causes neurotransmitters to spill out The neurotransmitters bind with the receiving cell Blind with the receiving cell Open channels allowing either sodium or chloride Cl to pass into the receiving cell Thus the connection can either be excitatory or inhibitory The Lock and Key Model There are many neurotransmitters Specific neurotransmitters fit into specific keyholes or receptors Drugs Work by enhancing or blocking synaptic transmission Overactive neurotransmitters can be blocked by drugs If a neurotransmitter is missing or inactive the drug can act as a substitute Drugs can block the channel by filling the receptor without completely filling it therefore not causing it to open Drugs can also block neurotransmitter reuptake released neurotransmitters that do not bind with receptors and taken back Tolerance and Withdrawal Physiological changes counteract drugs Tolerance more drugs are needed for the same effect Withdrawal some drug is needed for normal functioning Specialization of Function Central nervous system brain and spinal cord Peripheral nervous system nerves Peripheral Nervous System Skeletal nervous system controls skeletal muscles which are responsible for the movement of arms legs etc Autonomic nervous system controls glands and visceral muscles which are internal organs such as heart and lungs Sympathetic arouses fight or flight Parasympathetic calms regeneration and growth Central Nervous System Subcortical the brainstem thalamus and spinal cord Brainstem midbrain pons medulla Is considered more primitive Subcortical is responsible for locomotion and reflexes The pons and medulla are responsible for postural reflexes such as balance and vital reflexes like breathing heart rate metabolism etc Thalamus the relay station between the spinal cord and the brain Spinal Cat scientists severed the spinal cord from the brain of a cat the cat could still walk afterwards Cerebellum coordinates rapid movements such as throwing kicking playing music etc Basal Ganglia coordinates slower and deliberate movements such as reaching for a cup Limbic System regulates motivation emotions and memory Made of the hippocampus amygdala and hypothalamus Hippocampus unites memories to make sense of them Does not store the memories but connects them together Amygdala regulates and controls emotions Phineas Gage damages connections between the amygdala and higher areas in the cortex Cortical cortex Hypothalamus controls hunger and thirst Brain grey matter is the cell bodies The white matter is the wiring and myelin sheaths About the size of four sheets of paper Cerebral Cortex two hemispheres each with four lobes Frontal parietal occipital and temporal lobes Four main characteristics Specialization of function Topographical organization Cortical magnification Lateralization Specialization of Function Primary motor areas Primary sensory areas senses the outside world Association areas memory association decisions and meaning Topographical Organization Motor homunculus pictorial representation of the anatomical divisions within the cortex The