[bioundgrd] brain & cog lecture 4/11

[Rachel McPherson]

The Department of Brain & Cognitive Sciences is pleased to announce:
The 8th Annual Margaret Bidwell Memorial Lecture

Peter Strick, PhD
Professor, Department of Neurobiology, and Co-director Center for the 
Neural Basis of Cognition (CNBC)
University of Pittsburgh
Building blocks for movement in the motor cortex

4:00 PM, Tuesday April 11th, 2006
46-3002 Auditorium

Abstract:
How are the cortical neurons that control a muscle distributed in the 
primary motor cortex (M1)?  To answer this classical question we used 
retrograde transneuronal transport of rabies virus from single 
muscles of macaques.  This enabled us to define cortico-motoneuronal 
(CM) cells that make monosynaptic connections with the motoneurons of 
the injected muscle.  We examined the distribution of CM cells that 
project to motoneurons of 3 thumb and finger muscles.  We found that 
the CM cells for these digit muscles are restricted to the caudal 
portion of M1 which is buried in the central sulcus.  Within this 
region of M1, CM cells for one muscle display a remarkably widespread 
distribution and fill the entire mediolateral extent of the arm area. 
In fact, CM cells for digit muscles are found in regions of M1 that 
are known to contain the shoulder representation.  The cortical 
territories occupied by CM cells for different muscles overlap 
extensively.  Thus, we found no evidence for a focal representation 
of single muscles in M1.  Instead, the overlap and intermingling 
among the different populations of CM cells may be the neural 
substrate to create a wide variety of muscle synergies.  Indeed, we 
will present physiological evidence that the task of the motor cortex 
is to function as a flexible central pattern generator.
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