examining-local-network-processing-using-multi-contact-laminar

Examining Local Network Processing using Multi-contact Laminar Electrode Recording

Cortical layers are ubiquitous structures throughout neocortex1-4 that consist of highly recurrent local networks. In recent years, significant progress ...

It is generally believed that attention enhances the processing of sensory information during perception and learning. Here we report that, contrary to common belief, attention limits the degree of plasticity induced by repeated exposure to image features. Specifically, daily exposure to oriented stimuli that are not linked to a specific task causes an orientation-specific improvement in perceptual performance along the "exposed" axes. This effect is modulated by attention: human subjects showed a larger improvement in orientation discrimination when attention is directed toward the location where stimuli are presented. However, the capacity to perform discriminations away from the exposed orientation is enhanced when the exposure stimuli are unattended. Importantly, the improvement in orientation discrimination at the unattended location leads to a robust enhancement in the discrimination of complex stimuli, such as natural texture images, with orientation components along the exposed axes, whereas the improvement in orientation discrimination at the attended location exhibits only weak transfer to complex stimuli. These results indicate that sensory adaptation by passive stimulus exposure should be viewed as a form of perceptual learning that is complementary to practice-based learning in that it reduces constraints on generalization.

Attention alters visual plasticity during exposure-based learning.

A fundamental feature of information processing in neocortex is the ability of individual neurons to adapt to changes in incoming stimuli. It is increasingly being understood that cortical adaptation is a phenomenon that requires network interactions. The fact that the structure of local networks depends critically on cortical layer raises the possibility that adaptation could induce specific effects in different layers. Here we show that brief exposure (300 ms) to a stimulus of fixed orientation modulates the strength of synchronization between individual neurons and local population activity in the gamma-band frequency (30-80 Hz) in macaque primary visual cortex (V1) and influences the ability of individual neurons to encode stimulus orientation. Using laminar probes, we found that although stimulus presentation elicits a large increase in the gamma synchronization of rhythmic neuronal activity in the input (granular) layers of V1, adaptation caused a pronounced increase in synchronization in the cortical output (supragranular) layers. The increase in gamma synchronization after adaptation was significantly correlated with an improvement in neuronal orientation discrimination performance only in the supragranular layers. Thus, synchronization between the spiking activity of individual neurons and their local population may enhance sensory coding to optimize network processing across laminar circuits.

Adaptation-induced synchronization in laminar cortical circuits.

Ein grundlegendes Merkmal der Informationsverarbeitung im Neocortex ist die F&auml;higkeit der einzelnen Neuronen zur Anpassung an &Auml;nderungen im eintreffende Reize. Es ist zunehmend erkannt wird dass kortikale Anpassung ein Ph&auml;nomen ist, das Netzwerk Interaktionen erfordert. Die Tatsache, dass die Struktur der lokalen Netzwerke kritisch, kortikale Schicht abh&auml;ngt l&ouml;st die M&ouml;glichkeit, dass Anpassung spezifische Wirkungen in verschiedenen Schichten ausl&ouml;sen kann. Hier zeigen wir, dass kurzer Exposition (300 ms) auf einen Reiz der feste Orientierung die St&auml;rke der Synchronisierung zwischen einzelnen Neuronen und lokale Bev&ouml;lkerung Aktivit&auml;t der Gamma-Band Frequenz (30-80 Hz) in Makak prim&auml;re Sehrinde (V1 moduliert) und beeinflusst die F&auml;higkeit der einzelnen Neuronen Reiz Orientierung zu codieren. Mit laminare Sonden, fanden wir, dass obwohl Reiz Pr&auml;sentation eine starke Zunahme der Gamma-Synchronisation rhythmische neuronaler Aktivit&auml;t in den Eingang (granularen) Schichten der V1 entlockt, Anpassung in Synchronisierung in den kortikalen Ausgabe (Supragranular)-Schichten eine ausgepr&auml;gte Erh&ouml;hung verursacht. Der Anstieg der Gamma-Synchronisation nach der Anpassung deutlich mit einer Verbesserung der neuronalen Orientierung Diskriminierung Leistung nur in den Supragranular Schichten korrelierte. Somit kann Synchronisierung zwischen der Blindkontrollen Aktivit&auml;t von einzelnen Neuronen und ihrer lokalen Bev&ouml;lkerung verbessern sensorische Kodierung zur Optimierung der Netzwerk-Verarbeitung in laminar Schaltungen.

Article	Year
Attention alters visual plasticity during exposure-based learning. Current biology : CB\| PubMed ID: 19268592	2009
Adaptation-induced synchronization in laminar cortical circuits. Proceedings of the National Academy of Sciences of the United States of America\| PubMed ID: 21659632	2011

Bryan J. Hansen

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