Graded potentials

Graded potentials - Graded potentials- strength determined...

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Graded potentials- strength determined by amount of neurotransmitter bound by receptors -lose strength as they spread out from point of origination Eric Kandel- -studied sea snail, aplysia’s, startle reflex -snails would withdraw gills at touch -eventually, snail habituated and Kandel saw a decrease in neurotransmitter released by neurons controlling gill-withdrawal reflex -changes in synaptic transmission underlie changes in behavior NEUROTRANSMITTERS- Acetylcholine -found in both central and peripheral nervous systems -in parasympathetic system, Ach is used to transmit nerve impulses to muscles -in central nervous system, Ach linked to Alzheimer’s (progressive and incurable loss of memory); Ach lost in neurons connected to hippocampus Monoamine Neurotransmitters Catecholamines -epinephrine, norepinephrine, dopamine; also known as monoamines, biogenic amines -play important role in emotions -NE (adrenaline): important for alertness and wakefulness, implicated in depression and mania; too much NE results in mania (intense euphoria and impaired judgment); too little NE and SE results in depression -dopamine important in movement and posture; normally found in the basal ganglia (brain region that helps our movements be smooth and posture steady); -DA hypothesis: too much DA or too much sensitivity to DA may result in delusions, hallucination, and agitation found in schizophrenia; amphetamines increase DA at synapse and too much amphetamines results in psychosis, disorder resembling paranoid schizophrenia; antipsychotic drugs, like phenothiazines are thought to decrease DA receptor sensitivity -Parkinson’s disease- result of too little DA neurons in basal ganglia in substantia nigra; disruption of DA leads to jerky movements; anti-psychotic drugs have Parkinson’s-like side effects called tardive dyskinesia; motor movements can be treated with L-dopa, a
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Graded potentials - Graded potentials- strength determined...

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