resting potential and membrane potential
more positive outside
more negative inside
difference in potential of 70mv
chemical gradients
more na (sodium) outside more K (potassium) inside
action potentials
occur at thresholds of 55 mv all or none phenomenon constant amplitude - 100mv constant time course - 1 or 2 ms followed by refractory period (5 ms)
self regenerating propogation
action potentials travel down to axons to synapses without losing their strength
neurotransmitter
synaptic cleft
receptors
signal from pre to post synaptic cell is chemical
gap between pre and post synaptic cell
reception of neurotransmitter by post synaptic cell causes post synaptic potential (PSP)
Post synaptic potential
originate at synapses
graded (large or small)
propagate electronically to axon hillock
depend on neurotransmitter and receptors
EPSP
IPSP
increase in positive charge inside the cell
increase the negative charge inside the cell
PSP vary in
size: how much neurotransmitter and how many receptors
sign: type of transmitter and receptors
speed: ionotropic of metabtropic receptors
temporal summation
spatial summation
PSPs from different times can sum together at the axon hillock
-PSPs from different synapses sum together at the axon hillock
integrate and fire (neural function)
the inputs are graded (vary along a continuum)
- at each point in time, the neuron sums all of its inputs ad fires or not
- output is all or none
center surround receptive field
retinal ganglion cells
-on center and off surround
off center on surround
if the light is focused on the on area then there will be firing of the cell - cant cover the whole thing or it will inhibit
emphasize edges to give us info about external environment
lateral inhibition
inhibits the action of the neighbouring neuron when it itself is excited
-brain pinpoints where the exact stimulus is coming from
superior colliculus
regulates involuntary eye movements
dorsal stream
ventral stream
where/how pathway (parietal lobe)
-what/why pathway (temporal lobe)
ocular dominance columns
stripes when visual field (left and right) overlap
-centre of visual field
orientation columns
represent light at same locaiton but different orientations
