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Short-Term Depression in Thalamocortical Synapses of Cat Primary Visual Cortex
- Publication Year :
- 2005
- Publisher :
- Society for Neuroscience, 2005.
-
Abstract
- Neurons in primary visual cortex exhibit several nonlinearities in their responses to visual stimuli, including response decrements to repeated stimuli, contrast-dependent phase advance, contrast saturation, and cross-orientation suppression. Thalamocortical synaptic depression has been implicated in these phenomena but has not been examined directly in visual cortexin vivo. We assessed depression of visual thalamocortical synapsesin vivousing 20-100 Hz trains of electrical stimuli delivered to the LGN. Cortical cells receiving direct input from the LGN, identified by short latency and low jitter of LGN-evoked PSPs, showed moderate reductions in PSP amplitude during the fastest trains. Cells receiving indirect input from the thalamus via other cortical excitatory neurons show a marked reduction in PSP amplitude during a train, which could be explained either by synaptic depression in corticocortical synapses or by an inhibition-mediated suppression of the firing of their afferents. Reducing spontaneous activity in the LGN (by retinal blockade) unmasked additional depression at the thalamocortical synapse but only for the first stimulus in the train. That is, the first PSP was increased in amplitude relative to the unblocked condition, but subsequent responses were essentially unchanged. Thus, the synapses are maintained at significant levels of depression by spontaneous activity. These findings constrain the role that thalamocortical depression can play in shaping cortical responses to visual stimuli.
- Subjects :
- Visual perception
Time Factors
genetic structures
Thalamus
Models, Neurological
Behavioral/Systems/Cognitive
Stimulus (physiology)
Neurotransmission
Synaptic Transmission
Synapse
chemistry.chemical_compound
medicine
Animals
Visual Cortex
Neurons
General Neuroscience
Long-Term Synaptic Depression
Electric Conductivity
Geniculate Bodies
Retinal
Electric Stimulation
Visual cortex
medicine.anatomical_structure
chemistry
Synapses
Excitatory postsynaptic potential
Cats
Psychology
Neuroscience
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Accession number :
- edsair.doi.dedup.....5f0cccd5e659f2d9e128fd5afbc94b75