NIH VideoCast - Microcircuits of the Medial Entorhinal Cortex and a Theory of Spatial Memory Formation

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Microcircuits of the Medial Entorhinal Cortex and a Theory of Spatial Memory Formation

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Air date:	Monday, June 21, 2010, 12:00:00 PM Time displayed is Eastern Time, Washington DC Local
Views:	Total views: 255 * This only includes stats from October 2011 and forward.
Category:	Neuroscience
Runtime:	00:58:50
Closed captioning:	Check box to display CC outside of the video Note: You can drag the captioning window around and resize it
Description:	Rodent medial entorhinal cortex represents both spatial information (in grid cells) and head-direction information but the microcircuits integrating the two types of signals are unknown. To explore the relationship between activity and neuronal connectivity in the MEC, Dr. Brecht's lab developed a new method for recording and labeling single neurons by juxtacellular stimulation in freely-moving rats. Their method is based on novel a head-mountable, friction-based devise for mechanical stabilization of the glass pipette during the recording. They find that large fraction of grid-cells were spiny stellate neurons organized in about 500-700 small patches in layer 2. Grid cells and other superficial layer neurons were mainly active during exploration. Deep layers neurons in contrast rarely showed exploration activity and became active at rest. Most head-direction-cells were aspiny neurons residing in a system of about 25 pairs of large patches at the dorso-medial borders of medial entorhinal cortex. Head-direction-patches are large clusters of layer 2 neurons inserted in the cortical sheet with little or no other cortical layers associated. They identify three long-range axon systems in the MEC: A system of centrifugal axons, through which most if not all grid-cells axons target single head-direction-patches. A system of centripetal axons, through which most if not all head-direction-cells target single grid patches. A system of circumcurrent axons through which head-direction-cells connected many other head-direction patches. They suggest a microcircuit model how these axons might function in the alignment and formation of entorhinal maps. Accordingly, circumcurrent axons impose a global “one head-direction” constraint. Centripetal axons rotate grid orientations upon head movements and centrifugal axons send a “stop rotate-signal”. Assuming that grid cell firing increases with the fit of landmark inputs to grid vertices such a circuit could align head-direction and map information. In a novel environment the entorhinal map could be fractured and aligned to landmarks by the relative rotation of the orientation of grid-patches. NIH Neuroscience Seminar Series

NLM Title:	Microcircuits of the medial entorhinal cortex and a theory of spatial memory formation / Michael Brecht.
Author:	Brecht, Michael. National Institutes of Health (U.S.)
Publisher:
Abstract:	(CIT): Rodent medial entorhinal cortex represents both spatial information (in grid cells) and head-direction information but the microcircuits integrating the two types of signals are unknown. To explore the relationship between activity and neuronal connectivity in the MEC, Dr. Brecht's lab developed a new method for recording and labeling single neurons by juxtacellular stimulation in freely-moving rats. Their method is based on novel a head-mountable, friction-based devise for mechanical stabilization of the glass pipette during the recording. They find that large fraction of grid-cells were spiny stellate neurons organized in about 500-700 small patches in layer 2. Grid cells and other superficial layer neurons were mainly active during exploration. Deep layers neurons in contrast rarely showed exploration activity and became active at rest. Most head-direction-cells were aspiny neurons residing in a system of about 25 pairs of large patches at the dorso-medial borders of medial entorhinal cortex. Head-direction-patches are large clusters of layer 2 neurons inserted in the cortical sheet with little or no other cortical layers associated. They identify three long-range axon systems in the MEC: A system of centrifugal axons, through which most if not all grid-cells axons target single head-direction-patches. A system of centripetal axons, through which most if not all head-direction-cells target single grid patches. A system of circumcurrent axons through which head-direction-cells connected many other head-direction patches. They suggest a microcircuit model how these axons might function in the alignment and formation of entorhinal maps. Accordingly, circumcurrent axons impose a global "one head-direction" constraint. Centripetal axons rotate grid orientations upon head movements and centrifugal axons send a "stop rotate-signal". Assuming that grid cell firing increases with the fit of landmark inputs to grid vertices such a circuit could align head-direction and map information. In a novel environment the entorhinal map could be fractured and aligned to landmarks by the relative rotation of the orientation of grid-patches.
Subjects:	Entorhinal Cortex--physiology Memory--physiology Neural Pathways--physiology Spatial Behavior--physiology
Publication Types:	Lecture Webcast
NLM Classification:	WL 307
NLM ID:	101535283
CIT Live ID:	9364
Permanent link:	https://videocast.nih.gov/watch=9364

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