Individual variation in brain organization

Synopsis

Brain organization is who we are: our personalities and abilities are determined by the connections of neurons. Learning is a change in this organization. For example, when an animal has been trained to reach precisely for a food pellet, the area of cortex devoted to control of the reaching hand is enlarged. Such "cortical magnification" of the representation of important body parts is thought to improve relevant sensorimotor processing. Therefore, the arrangement of the representation of muscles and movements in the neocortex provides a window into the behavioural priorities of the brain.

Decades of "cortical mapping" have led to a consensus among neuroscientists that brain organization varies significantly between individuals, even between untrained laboratory animals reared in identical conditions. But does a brain's baseline organization affect how much or what kinds of change can take place with practice and experience? Before asking such questions we need to understand what parameters vary between brains and the scale of these differences, both of which are currently unknown.  

I am conducting the first systematic study of variation in brain organization using as my model system the motor cortex and surrounding network of sensorimotor brain areas that integrate sensory information to guide movement. I will describe preliminary studies mapping functional organization and reversibly deactivating portions of the network to simulate brain injury during skilled reaching behaviour. Next I will describe plans to refine these techniques and combine them with EMG data from 20-30 muscles to create extremely dense maps of brain organization in rats that will be used to characterize variation. My goal is to test if certain cortical variants are correlated with greater motor skills or are more resistant to brain injury.