Psychology Final Exam Neuropsychology I The neuron 10 billion to a trillion Dendrites cell body soma axon terminal endings terminal buttons Nerve impulse action potential Process 1 Start with electrical resting potential inside of cell is 70 mV more negative than outside due to Cl ions inside and Na ions outside so resting potential is 70 mV 2 Stimulation of neuron lets in Na ions which makes the inside more positive 70 69 68 67 3 When enough Na ions get in for the potential to be reduced to 55 mV suddenly the doors ion gates to the cell membrane are flung open allowing Na to rush in 4 So much Na enters that the potential doesn t just go to 0 it shoots all the way up to 40 mV so the inside is now positive relative to the outside the action potential Ion pumps work to reduce potential back to 70 mV by pushing positive ions out actually K because Na goes out slower then another pump takes Na back out and puts K back in 5 Note 55mV is a threshold below that voltage there is no action potential firing is all or none More intense stimulation doesn t cause a more intense action potential just more frequent ones up to 1000 sec and in more neurons Action potential travels down length of axon by depolarizing neighboring areas Travels NOT at speed of electrical current in wire but rather at about 50 to 100m sec Communication across the synapse Neurotransmitters 1 Synapse is gap between two neurons the presynaptic and the postsynaptic neurons terminal endings of presynaptic neuron relay impulse to dendrites of postsynaptic neuron 2 Terminal buttons contain little sacs vesicles of chemicals neurotransmitters At action potential vesicles burst and release neurotransmitters into synapse 3 Receptor molecules on membrane of dendrite are like little locks to be opened neurotransmitters are the keys and this is what opens ion gates to allow Na inside in the first place 4 Neurotransmitters may open a gate to let Na inside excitatory more likely to fire because potential is getting smaller toward 55 OR they may open a gate that pushes positive K ions out inhibitory less likely to fire because potential is getting larger e g 70 71 72 Central nervous system CNS center includes brain and spinal cord Peripheral nervous system PNS away from center includes everything but brain and spinal cord A Somatic division body nerve fibers connecting to muscles senses B Autonomic division self rule regulates vital functions heart rate breathing digestion etc 1 Sympathetic branch 2 Parasympathetic branch with feeling excited states energy consuming arousal mobilizes for emergency speeds heart and lungs inhibits digestion and sex etc goes with sympathetic vegetative states energy conserving or storing calms maintains normal functioning slows heart and lungs etc Brain bottom to top inside to outside old to new Hindbrain medulla breathing heartbeat blood circulation pons arousal and attention cerebellum integration of muscles to perform fine movements but no coordination direction of these movements balance Ex cat transected above hindbrain can move but not act Midbrain forms movements into acts controls whole body responses to visual and auditory stimuli Ex cat transected above midbrain can act but without regard to environment without purpose Forebrain Thalamus sensory and motor relay center to various cerebral lobes Hypothalamus controls responses to basic needs food temperature sex Basal ganglia regulates muscle contractions for smooth movements Limbic system memory hippocampus and emotion amygdala Cerebral cortex or neocortex four lobes frontal parietal occipital temporal seat of higher intellectual functions Ex cat transected above limbic system acts normal with purpose but clumsy Cerebral Hemispheres or Cerebrum Corpus callosum o Connects hemispheres o Each hemisphere controls OPPOSITE SIDE of body Cerebral cortex skin or bark o 1 to 3 mm thick 2 or 3 square feet if flattened out o Higher motor sensory and intellectual functions Four Lobes of Cortex Frontal lobe planning social behavior motor control o Front of brain Parietal lobe somatosensory sense of touch o On top and toward back of brain Occipital lobe vision o Back of brain Temporal lobe hearing memory o Side of brain Two General Rules of Cortical Function 1 Left Hemisphere language Right Hemisphere spatial abilities 2 Front expression actions plans Back reception perceptions interpretations Damage to Non Primary Association Cortex Pre frontal lesions loss of planning moral reasoning sensitivity to social context or loss of initiation of action deliberation Apraxia no doing failure in sequencing components of actions inability to organize familiar movements o Frontal lesions just forward of motor cortex o NOT paralysis as from motor cortex lesion Agnosia no knowing o Deficit in interpreting categorizing labeling knowing o Occipital visual or temporal auditory lesions o Sensory systems themselves e g eyes are okay Neglect Right hemisphere parietal damage causes inattention to whole left side Aphasia Left hemisphere frontal or temporal damage causes deficits in language function Aphasia disorder of language Left hemisphere brain lesions Essentially apraxia if lesion is in front or agnosia if lesion is in back of language Expressive aphasia cannot produce speech o Lesion to Broca s area frontal association area Receptive aphasia cannot understand speech and consequently cannot produce speech o Lesion to Wernicke s area back association area Split Brain Studies Sever corpus callosum to reduce severity of seizures Leaves patient mostly normal but with left and right brain independent in subtle ways Note visual pathways Left side of each eye sends info to left hemisphere Right side of each eye sends info to right hemisphere Result Left visual field goes to right hemisphere Right visual field goes to left hemisphere Experiment on split brain patient 1 Patient looks straight ahead picture flashed quicker than eyes can move ask what did you see a Picture of cup on right LH says cup b Picture of spoon to left LH says nothing 2 BUT when told to reach for that object with the left hand RH grabs spoon 3 Ask what is it and LH guesses pencil and RH may frown at that Learning II Classical Conditioning US unconditioned stimulus e g food in mouth input to a reflex UR unconditioned response e g salivation to food output of reflex CS conditioned stimulus e g bell initially results in investigatory response then habituation after conditioning results in CR CR conditioned