PSY 312 Exam 2 Terms UKY

Concentration gradient

move from high concentration to low concentration

graded

weak signal, small PSP. Strong signal, large PSP

decremental

lose amplitude as they travel

depolarize

EPSP, increase likelihood that neuron will fire

hyperpolarize

IPSP, decrease likelihood neuron will fire

spatial summation

EPSP sum to form greater EPSP, IPSP sum to form greater IPSP

Temporal summation

PSP produced in rapid succession to form greater signal.

threshold 

depolarize membrane to -55 mv and AP is generated

absolute refractory period

impossible to elicit a second AP

relative refractory period

possible to elicit another AP but only is higher than normal stimulation is applied.

antidromic conduction

AP goes axon→cell body

orthodromic conduction

AP goes cell body→ terminal buttons

axodendritic synapse

axon terminal buttons on dendrites

axosomatic synapses

axon terminal buttons on soma

dendrodendritic synapse

transmission in either direction

axoaxonic synapse

axon terminal synapse onto another axon terminal

directed synapse 

site of NT release and site of NT reception are close 

nondirected synapse

site of NT release and NT reception are not close.

autoreceptor

metabotropic receptors that monitor number of NT in synapse to reduce release when levels are high and increase release when levels are low.

agonist drug 

facilitates or activates the effect of an NT

antagonist drug

inhibits or blocks the effects of an NT

totipotent

cell can develop into any class of cell

pluripotent

cell can develop into many but not all classes of cells

multipotent

cell can develop into different cells of only one class

unipotent

cell can develop into only one type of cell

radial migration

proceeds in straight line toward outer wall of tube, towards brains surface 

tangential migration

parallel to tube walls and brains surface

somal translocation

extension grows from cell into direction of migration, explores environment for cues.

glia-mediated migration

tube wall thicken, radial glial cells appear and cells move along glial networks 

aggregation

aligning themselves with other developing neurons that migrated to the same area to form structures of the nervous system.

cell adhesion molecules

mediate migration and aggregation

growth cone

at dendrite, extends and retracts filopodia as if searching for the correct route

necrosis

passive, cell breaks apart and spills contents in extracellular fluid

apoptosis

active, packaged before the cell breaks apart.

neurotrophins

promote growth and survival of neurons, axon guidance molecules, stimulat synaptogensis

nerve growth factor

first neurotrophin to be isolated

synapse rearrangement

as neurons die, the space they leave is filled by sprouting axon terminals of surviving neurons.

chemoaffinity hypothesis

each postsynaptic surface releases a specific chemical label and that each growing axon is attracted by the label to its target

pioneer growth cones

first growth cones to travel along one particular route

fasciculation

tendency of axons to grow along paths established by preceding axons

topographic gradient hypothesis

axons growing from one topographic surface to another are guided to specific targets

synaptogensis

once axons have reached their sites, they must establish synapses.

preservative error

children would continue to select the previously correct screen even though it was incorrect.

critical period

it is absolutely essential for an experience to occur within a particular time frame in influence development, strict timeframe

sensitive period

if an experience has a great effect on development when it occurs during a particular interval but can still have weak effect outside of the interval, flexible timeframe

heterogenous

some may be impaired, some may be superior

savants

people with developmental disabilities who display amazing or specific cognitive or artistic abilities