PSYC100 0917 Action Potential Stimulation of the neuron causes the channels to open inside of the membrane becomes more positive When reaches threshold neuron fires Sodium then rushes in Characteristics of impulses All or nothing Fixed Amplitude the strength amplitude of the neural impulses is always the same Each action potential remains the same for each neuron independent of the intensity of the stimulus The stronger the stimulus effects the rate of the firing but not each shot Propagation of the action potential continued Chemical communication between neurons Neurotransmitters are chemical messengers They are stored in the synaptic vessels Neurotransmitters bind to the postsynaptic membrane Diffuse across the synapse first and then bind to the receptors Lock and Key metaphor similarity of their structural configuration matters The binding of the neurotransmitter to the receptor affects ion channels Thus it will contribute to either the stimulation or inhibition of the action potential in the postsynaptic neuron Brain is most important organ to psychology Average adult brain weighs 1400g 3 pounds Functions Perception integration and association neural activity resulting In coordinated motor responses Hemispheric lateralization brain can roughly be divided into cerebrum cerebellum brain stem Input to the brain comes from the spinal cord and cranial nerves Output comes from brain stem spinal cord and cranial nerves gray matter contains the cell bodies of neurons white matter consists of tracts containing myelinated axons Foramina are holes in the skull through which nerves pass The foramen magnum is the largest hole Both the brain and spinal cord float in cerebrospinal fluid CSF CSF acts as the shock absorber Medulla is responsible for heartbeat breathing muscle tone swallowing Pons a larger swelling above the medulla Have a role in arousal sleep and dreaming Also have influence in coordination movements on the right and left sides of the body Reticular Formation interconnected neurons running through the pons and medulla and beyond It is responsible for keeping you alert and aroused Also the ability to selectively attend to certain stimuli and ignore constant unchanging stimuli One parts is the reticular activating system which stimulates the upper part of your brain keeping you awake and alert Suggested that this is involved in ADD and comas Cerebellum at the base of the skull behind the pons It is below the main part of the brain It controls all involuntary rapid and fine motor movements and coordinated motor movements and balance Also coordinates voluntary movements that must take place in rapid succession helps keep track of where your arms and legs are The cerebral hemispheres determine what you do and the cerebellum works out the details Because of your cerebellum you don t have to consciously think about your posture muscle tone and balance Learned reflexes skills habits are stored there Hippocampus located w in the temporal lobes on both side of the brain Important for long term permanent memories Acetylcholine is important for the memory functions of the hippocampus Amygdala responsible for fear responses and memory of fear Sensory information goes here prior to the higher parts of the brain Thus people can react to danger very quickly Kluver Bucy Syndrome 1939 discovered that monkeys with large amounts of their temporal lobes removed including the amygdala were completely unafraid of snakes and humans
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