Journal Article

Gain control by layer six in cortical circuits of vision

Bortone, Dante S., Adesnik, Hillel, Scanziani, Massimo, Olsen, Shawn R.

2012

Overview

After entering the cerebral cortex, sensory information spreads through six different horizontal neuronal layers that are interconnected by vertical axonal projections. It is believed that through these projections layers can influence each other's response to sensory stimuli, but the specific role that each layer has in cortical processing is still poorly understood. Here we show that layer six in the primary visual cortex of the mouse has a crucial role in controlling the gain of visually evoked activity in neurons of the upper layers without changing their tuning to orientation. This gain modulation results from the coordinated action of layer six intracortical projections to superficial layers and deep projections to the thalamus, with a substantial role of the intracortical circuit. This study establishes layer six as a major mediator of cortical gain modulation and suggests that it could be a node through which convergent inputs from several brain areas can regulate the earliest steps of cortical visual processing. Layer six in the mouse primary visual cortex is a major mediator of cortical gain modulation and may be a node through which convergent inputs from several brain areas can regulate the earliest steps of cortical visual processing. Visual processing stacks up The cerebral cortex, which is responsible for perception and other cognitive functions, is composed of multiple distinct layers of cells. Little is known about how individual layers function, but here, Massimo Scanziani and colleagues establish the role of a specific cortical layer in sensory processing. Using optogenetics to selectively drive or suppress layer-six neurons in the mouse visual cortex — a previously impossible manipulation — the authors show that the neurons modulate the size of the response of upper-layer neurons to visual stimuli without changing their selectivity. The authors conclude that layer six plays a part in controlling the gain of visual cortical processing by interacting with other neurons in both the cortex and the thalamus.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 631/443/376 / Animals / Biological and medical sciences / Brain / Eye and associated structures. Visual pathways and centers. Vision / Fundamental and applied biological sciences. Psychology / Humanities and Social Sciences / Mice / Models, Neurological / multidisciplinary / Neural Inhibition - radiation effects / Neural Pathways - physiology / Neural Pathways - radiation effects / Neurology / Neurons - physiology / Neurons - radiation effects / Photic Stimulation / Science / Science (multidisciplinary) / Synapses - metabolism / Synapses - radiation effects / Thalamic Nuclei - cytology / Thalamic Nuclei - physiology / Thalamic Nuclei - radiation effects / Vertebrates: nervous system and sense organs / Visual Cortex - anatomy & histology / Visual Cortex - cytology / Visual Cortex - physiology / Visual Cortex - radiation effects / Visual Perception - physiology / Visual Perception - radiation effects