2022-09-26 カリフォルニア大学校アーバイン校(UCI)
フィードフォワード信号とフィードバック信号が、大脳新皮質の頭頂部にある単一ニューロンに収束していることを突き止めた。さらに、皮質ニューロンの種類が異なると、この2つの情報の流れが著しく異なる時間スケールで統合されることを発見し、これらの違いを支える細胞および回路の構造を明らかにした。
<関連情報>
- https://news.uci.edu/2022/09/26/uci-study-ids-what-brings-our-senses-and-thoughts-together/
- https://www.cell.com/neuron/fulltext/S0896-6273(22)00755-3
後頭葉皮質におけるフィードフォワードおよびフィードバック・シナプス入力の細胞型特異的な統合 Cell-type-specific integration of feedforward and feedback synaptic inputs in the posterior parietal cortex
Daniel J. Rindner,Archana Proddutur,Gyorgy Lur
Neuron Published:September 09, 2022
DOI:https://doi.org/10.1016/j.neuron.2022.08.019
Highlights
•PPC neurons receive converging monosynaptic input from frontal and sensory cortices
•L5 cell types display distinct temporal dynamics of multimodal synaptic integration
•Cell-type-specific ionic and inhibitory mechanisms shape integration timing
•Subthreshold integration dynamics translate to nonlinear action potential firing
Summary
The integration of feedforward (sensory) and feedback (top-down) neuronal signals is a principal function of the neocortex. Yet, we have limited insight into how these information streams are combined by individual neurons. Using a two-color optogenetic strategy, we found that layer 5 pyramidal neurons in the posterior parietal cortex receive monosynaptic dual innervation, combining sensory inputs with top-down signals. Subclasses of layer 5 pyramidal neurons integrated these synapses with distinct temporal dynamics. Specifically, regular spiking cells exhibited supralinear enhancement of delayed—but not coincident—inputs, while intrinsic burst-firing neurons selectively boosted coincident synaptic events. These subthreshold integration characteristics translated to a nonlinear summation of action potential firing. Complementing electrophysiology with computational modeling, we found that distinct integration profiles arose from a cell-type-specific interaction of ionic mechanisms and feedforward inhibition. These data provide insight into the cellular properties that guide the nonlinear interaction of distinct long-range afferents in the neocortex.
