LGN+Cortex 2 - Receptive field of ganglion cell On-center...

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Unformatted text preview: 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 Images fall on corresponding portions of the two retinas 1 2 3 4A 4B 4C 5 6 From lateral geniculate Simple cell in visual cortex Place microelectrode in visual cortex to record action potentials from neurons in visual cortex + + + + Simple cell in visual cortex Fires weakly when light goes OFF! + + + + Simple cell in visual cortex On region of receptive field + + + + Off region of receptive field Simple cell in visual cortex Present a stimulus that covers the entire ON region Neuron responds strongly + + + + Simple cell in visual cortex Present a stimulus that covers the entire OFF region Neuron responds strongly when light goes OFF + + + + Simple cell in visual cortex Bar that covers entire ON receptive field has best orientation Neuron responds strongly Best orientation + + + + Simple cell in visual cortex Other orientations are less effective or not effective at all Neuron response is weaker + + + + Simple cell in visual cortex Other orientations are less effective or not effective at all Neuron does not response + + + + Simple cell in visual cortex Bar at optimal orientation at any other region of space is ineffective Neuron does not response + + + + Simple cells in visual cortex have Orientation Specificity Most effective stimulus has a particular orientation that covers the entire ON region Neuron responds strongly + + + + All geniculate cells make excitatory connections with stellate cells in layer 4C + + + + + All stellate cells make excitatory connections with simple cortical neuron + + + + + 3 simple cells Cell fires + + Complex cell + + + + + 3 simple cells Cell fires + + Complex cell + + + + + + 3 simple cells Cell fires + + Complex cell + 3 simple cells Cell does not fire + + Complex cell Inhibitory + Inhibitory excitatory - - Neuron fires strongly Cell is excited No response Cell is inhibited No response Cell is inhibited No response Inhibitory surrounds cancel excitatory center and the cell is inhibited End-Stopped Cells only respond to a bar of light with a limited spatial extent Neuron fires strongly Cell is excited 1 2 3 4A 4B 4C 5 6 Complex and End-Stopped Simple and Complex Simple and Complex Center-surround Complex Complex From lateral geniculate ...
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