Society of Neuroscience(SfN) is having its annual meeting in Washington D.C.–I will be presenting a poster at SfN on the mouse visual system and the relevance of electrical coupling in vision.

Laminar Distribution of Gap Junctions in Mouse Primary Visual Cortex

         Naqi Haider, Michael Chary, and Ehud Kaplan

     Department of Neuroscience & Friedman Brain Institute
The Neuron Doctrine, proposed by Santiago Ramon y Cajal,
dominates neuroscience today. It describes the nervous
system as composed of discrete anatomical and functional
unitsneurons.The Reticular Theory, a competing view of
neuroscience supported by Camillo Golgi, viewed the nervous
system as a giant syncytium of interconnected cells. We now
know that neurons are often electrically coupled to each other
by gap junctions, which allow for the transmission of subthreshold
currents and molecules. Electrical coupling can form
networks between specific types of neurons. Gap Junctions
also form connections between neurons and glia. Electrical
coupling between neurons through gap junctions can change
those neuron’s response properties. In the mammalian cortex,
inhibitory neurons are more frequently coupled electrically than
excitatory neurons. Hubel and Wiesel (1962) demonstrated
orientation selective cells in the cat primary visual cortex (V1),
where inhibitory neurons are thought to sharpen a neuron's
orientation tuning. Therefore, understanding how inhibition
affects orientation tuning, it is important to determine the spatial
distribution of gap junctions across V1.

Here we present preliminary immunohistochemical data
showing the laminar distribution of connexin36 gap junctions in
the mouse primary visual cortex among parvalbumin positive
inhibitory neurons. Companion simulations indicate that the
distribution of gap junctions is important for the sharpening of
the orientation tuning curve mediated by intracortical inhibition.
We anticipate this study to lay the groundwork for studies on
whether gap junctions are important in the temporal evolution of
orientation tuning curves. Furthermore, our approach
demonstrates how to include the effect of gap junctions into
quantitative models of the visual system.

FullPoster: Laminar Distribution of Gap Junctions in Mouse Primary Visual Cortex