McGill University - School of Computer Science

Algorithms Seminar

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DATE: Wednesday, September 22nd, 1999
TIME: 16:30-17:30
PLACE: McConnell 320
TITLE: Non-Random Patterns of Synaptic Connectivity in Neuronal Networks.
SPEAKER: Dr. Danny Baranes, Department of Anatomy and Cell biology, McGill University

Neuronal networks, the basic information processing units in the brain, specify their function by unique assembly of their synaptic connections into patterns of connectivity during development. We have identified a novel mechanism of neuronal connectivity in vivo and in vitro, which may play a key role in fashioning the circuitry within neuronal networks.

Neurites, neuronal processes through which information is transmitted between neurons (dendrites - receiving information; axons - transmitting information) predominantly grow through intersections between other neurites. This results in the formation of multi-neurite intersections (MNIs) at frequencies higher than those in simulated neuronal networks where neurons are positioned randomly. The system is reinforced by activity-mediated addition of neurites to the existing MNIs. This behavior gives rise to highly organized geometrical shapes, or polygon-like spaces, between bundles of neurites connected through MNIs. Axons involved in these gigantic intersections cluster their synaptic connections at the points of intersection.

In addition, they make multi-synaptic connections with several of the intersecting dendrites and occasionally switch targets at intersections. Thus, wiring of neurons through MNIs increases and patterns synaptic connectivity in the neuronal network.

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