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Date and Time 2015-07-21 15:00 - 16:00
Venue Seminar roomC301
Speaker Tatsuo Sato
Affiliation Carandini Laboratory, UCL Institute of Ophthalmology, Visual Neuroscience, University College London
Title 感覚神経回路形成研究チーム主催セミナー　Probing the function of distal network connectivity in visual cortex
Host Takeshi Imai
Summary （This seminar will be held in Japanese. 日本語でのセミナーです。）

Neurons in different locations across the cortex are connected through polysynaptic networks including both excitatory and inhibitory neurons. However, it is not known how the networks recruit synaptic excitation and inhibition. It is also not known whether their overall impact is increase or decrease in spike activity, and whether their impact is fixed or depends on other factors.
To answer these questions, we triggered fixed amount of spikes optogenetically in a local region of mouse primary visual cortex (V1), and then investigate their causal effects on a distal V1 region. Extracellular measurements showed that this local activation had two effects on spike activity at distal locations1: drive when cortex was silent, and suppression when sensory-stimulated. The balance between the two depended on strength of visual stimulation, and was correctly captured by a divisive normalization, one of canonical cortical computations. Furthermore, in vivo whole-cell recordings revealed that drive as caused by increase in synaptic excitation and inhibition, whereas suppression was mediated not by increase in inhibition but by decrease in both excitation and inhibition2. These results indicate that distal network connectivity can flexibly recruit or disengage synaptic inputs, achieving adaptable impact on spike activity at distal cortical sites.

References

1) Distal connectivity causes summation and division across mouse visual cortex
Sato, Häusser and Carandini, Nature Neuroscience, 2014

2) An excitatory basis for normalization in mouse visual cortex
Sato, Haider, Häusser and Carandini, submitted
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