Lecture 21- Neural processing in retina copy

Lecture 21- Neural processing in retina copy - horizontal...

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Unformatted text preview: horizontal cells Ganglion cells Bipolar cells No response No Receptive field of ganglion cell With On-center Off-surround Place microelectrode in optic nerve to record action potentials from retinal ganglion cells Ganglion cell fires when light is on Flash a spot of light On the screen + We mark that location with a plus sign (+) Receptive field of ganglion cell With On-center Off-surround Ganglion cell fires when light goes off Flash another spot of light on the screen + - We mark that location with a minus (-) Receptive field of ganglion cell With On-center Off-surround Keep flashing lights In different locations Ganglion cell fires when light goes off + -+- Neuron’s receptive field is all spatial locations from which light can influence the neuron’s ability to evoke discharges Receptive field of ganglion cell With On-center Light presented from any location outside of the receptive Off-surround field does has no influence on the neuron No response No response + +- Receptive field of ganglion cell On-center Off-surround Light on Ganglion cell fires when light is on Keep flashing lights In different locations Ganglion cell fires when light goes off + -+- Neuron’s receptive field is all spatial locations from which light can influence the neuron’s ability to evoke discharges Ganglion cell light light Synaptic connection from horizontal to bipolar cell Ganglion cell light Synaptic connection from horizontal to bipolar cell Ganglion cell light light light Ganglion cell Off response Off response Off response Inhibitory synapse excitatory synapse glutamate Glutamate activates G Protein that removes cGMP cG M P Na cGMP + Na + Na + Na + Inhibitory synapses on bipolar cells are mediated by metabotropic glutamate receptors that act just like rhodopsin in rods glutamate cG M P Na cGMP + Na + Na + Na + Inhibitory synapses on bipolar cells are mediated by metabotropic glutamate receptors that act just like rhodopsin in rods glutamate Glutamate activates G Protein that removes cGMP cG M P Na cGMP + Na + Na + Na + + ----K + K Off Center Receptive field depolarized Membrane potential 0 mv hyperpolarized Membrane potential Light on 0 mv -75 mv -75 mv depolarized + 0 mv + Light on 0 mv -75 mv -75 mv depolarized + 0 mv + 0 mv Light on -75 mv -75 mv On Center depolarized Membrane potential 0 mv hyperpolarized Membrane potential 0 mv Light on -75 mv -75 mv hyperpolarized 0 mv depolarized 0 mv -75 mv Light on -75 mv Rest (Ek) 0 mv depolarized 0 mv + -75 mv + Light on -75 mv off center - on surround shine light on surround membrane p ot e nt ial shine light on center dark light on + on surround + + dark light on ++ + off center me mbrane p o t e n t ia l dark light on dark light on dark light on dark light on light on o ticn rv p ee light on o ticn rv p ee Horizontal cell makes an Inhibitory connection with bipolar cell on center - off surround shine light on surround mm ra e ebn p te tia on l shine light on center light on + +_ + off surround dark light on +_ + + on center mmrane eb potential dark light on dark light on dark light on dark light on light on o ticn rv p ee light on o ticn rv p ee Horizontal cell makes an excitatory connection with bipolar cell ...
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