Short-Term Depression in Thalamocortical Synapses of Cat Primary Visual Cortex

Boudreau, C. Elizabeth; Ferster, David

doi:10.1523/jneurosci.1445-05.2005

Cited by 134 publications

(168 citation statements)

References 71 publications

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“…Our most recent estimates indicate that there are only an average of between 100 and 300 thalamic synapses per SS cell (Peters and Payne, 1993;Ahmed et al, 1994;Anderson et al, 1994;Binzegger et al, 2004). This contrasts with the rat barrel cortex, where the thalamic axons (Boudreau and Ferster, 2005;Banitt et al, 2007) are estimated to form ϳ600 synapses with their targets (Bruno and Sakmann, 2006; but see Meyer et al, 2010).…”

Section: Introductionmentioning

confidence: 78%

“…The excitatory input to spiny stellate (SS) cells is dominated by the input from layer 6 pyramids and other layer 4 pyramids (Ahmed et al, 1994;Binzegger et al, 2004). Even though activation of single dLGN afferents in vitro evokes twofold larger EPSPs than the other known inputs to the layer 4 SS cells (Stratford et al, 1996;TarczyHornoch et al, 1999), the thalamocortical synapses undergo short-term depression that offsets this advantage in vivo (Boudreau and Ferster, 2005;Banitt et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

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How Thalamus Connects to Spiny Stellate Cells in the Cat's Visual Cortex

Costa¹,

Martin²

2011

J. Neurosci.

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In the cat's visual cortex, the responses of simple cells seem to be totally determined by their thalamic input, yet only a few percent of the excitatory synapses in layer 4 arise from the thalamus. To resolve this discrepancy between structure and function, we used correlated light and electron microscopy to search individual spiny stellate cells (simple cells) for possible structural features that would explain the biophysical efficacy of the thalamic input, such as synaptic location on dendrites, size of postsynaptic densities, and postsynaptic targets. We find that thalamic axons form a small number of synapses with the spiny stellates (188 on average), that the median size of the synapses is slightly larger than that of other synapses on the dendrites of spiny stellates, that they are not located particularly proximal to the soma, and that they do not cluster on the dendrites. These findings point to alternative mechanisms, such as synchronous activation of the sparse thalamic synapses to boost the efficacy of the thalamic input. The results also support the idea that the thalamic input does not by itself determine the cortical response of spiny stellate cells, allowing the cortical microcircuit to amplify and modulate its response according to the particular context and computation being performed.

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Section: Introductionmentioning

confidence: 78%

Section: Introductionmentioning

confidence: 99%

How Thalamus Connects to Spiny Stellate Cells in the Cat's Visual Cortex

Costa¹,

Martin²

2011

J. Neurosci.

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“…This mechanism is ubiquitous in vertebrate neural circuits (Boudreau and Ferster 2005) and may thus contribute to directional selectivity and other spatiotemporal computations across sensory modalities and species.…”

Section: Resultsmentioning

confidence: 99%

Differences in the Time Course of Short-Term Depression Across Receptive Fields Are Correlated With Directional Selectivity in Electrosensory Neurons

Chacron

Toporikova

Fortune

2009

Journal of Neurophysiology

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Chacron MJ, Toporikova N, Fortune ES. Differences in the time course of short-term depression across receptive fields are correlated with directional selectivity in electrosensory neurons. J Neurophysiol 102: 3270 -3279, 2009. First published September 30, 2009 doi:10.1152/jn.00645.2009. Directional selectivity, in which neurons respond preferentially to one direction of movement ("preferred") over the opposite direction ("null"), is a critical computation that is found in the nervous systems of many animals. Here we show the first experimental evidence for a correlation between differences in short-term depression and direction-selective responses to moving objects. As predicted by quantitative models, the observed differences in the time courses of short-term depression at different locations within receptive fields were correlated with measures of direction selectivity in awake, behaving weakly electric fish (Apteronotus leptorhynchus). Because short-term depression is ubiquitous in the central nervous systems of vertebrate animals, it may be a common mechanism used for the generation of directional selectivity and other spatiotemporal computations.

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“…Recently, Freeman et al (2002) proposed that synaptic depression in thalamocortical synapses might underlie crossorientation suppression (but see Boudreau and Ferster, 2005). Based on their recordings in cat area 17, they suggest that a cortical basis is unlikely because the suppression is essentially immune to visual adaptation and is engaged by gratings drifting faster than 20 Hz, which exceeds the temporal resolution of most cells in primary visual cortex.…”

Section: Discussionmentioning

confidence: 99%

“…The time constant for recovery from synaptic depression in vitro is reported to be from 60 to 600 ms Thomson and Deuchars, 1997;Varela et al, 1997), whereas we observed recovery from suppression no more than 20 ms after response onset. Furthermore, Boudreau and Ferster (2005) studied synaptic depression at the thalamocortical synapse in anesthetized cats and concluded that synaptic depression is near saturation at spontaneous levels of activity. These findings that indicate synaptic depression is an unlikely source for cross-orientation suppression.…”

Section: Discussionmentioning

confidence: 99%

Dynamics of Suppression in Macaque Primary Visual Cortex

2006

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The response of a neuron in primary visual cortex (V1) to an optimal stimulus in its classical receptive field (CRF) can be reduced by the presence of an orthogonal mask, a phenomenon known as cross-orientation suppression. The presence of a parallel stimulus outside the CRF can have a similar effect, in this case known as surround suppression. We used a novel stimulus to probe the time course of cross-orientation suppression and found that it is very fast, starting even before the response to optimal excitatory stimuli. However, it occurs with some delay after the offset response, considered to be a measure of the earliest excitatory signals that reach the CRF. We also examined the time course of response to a stimulus presented outside the CRF and found that cross-orientation suppression begins substantially earlier than surround suppression measured in the same cells. Together, these findings suggest that cross-orientation suppression is attributable to either direct feedforward signal paths to V1 neurons or a circuit involving fast local interneurons within V1. Feedback from higher cortical areas is implicated in surround suppression, but our results make this an implausible mechanism for cross-orientation suppression. We conclude that suppression from inside and outside the CRF occur through different mechanisms.

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Short-Term Depression in Thalamocortical Synapses of Cat Primary Visual Cortex

Cited by 134 publications

References 71 publications

How Thalamus Connects to Spiny Stellate Cells in the Cat's Visual Cortex

How Thalamus Connects to Spiny Stellate Cells in the Cat's Visual Cortex

Differences in the Time Course of Short-Term Depression Across Receptive Fields Are Correlated With Directional Selectivity in Electrosensory Neurons

Dynamics of Suppression in Macaque Primary Visual Cortex

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