Rick M. Dijkhuizen, Ph.D.
MGH-NMR Center
Department of Radiology
Massachusetts General Hospital, Harvard Medical School
will speak on
Functional MRI of Reorganization in Rat Brain after Stroke
Abstract:
Stroke regularly causes acute loss of sensorimotor function. Although
often incomplete, some degree of functional recovery is common at later
stages, which has been associated with brain plasticity. Our goal was to
correlate recovery of sensorimotor function with changes in brain
activation patterns in relation to the cerebral pathophysiological status,
as measured with functional MRI techniques, in a rat stroke model. Our
results indicate that early after stroke, when sensorimotor deficits are
severe, activation-induced responses are absent in the damaged hemisphere
upon stimulation of the impaired forelimb. However, significant responses
are detected in the intact hemisphere, which is ipsilateral to the
stimulated forelimb. At chronic stages, when function of the impaired limb
has largely recovered, signs of activation are found in the infarction
borderzone and in the intact hemisphere. These findings of extension of
forelimb representational areas into adjacent cortical areas, and
activation responses in the intact hemisphere after unilateral stroke in
rat brain, are consistent with the reorganization observed in human brain
recovering from ischemic injury. Our data also suggest that the degree of
dysfunction of the impaired limb is related to loss of brain activation in
the contralateral sensorimotor cortex. Restoration of sensorimotor
function may be associated with recruitment of peri- and contralesional
functional fields in the brain.
The lecture will take place in the
Lecture Hall, Room 401, 44 Cummington St.
on Tuesday, October 25, 2000
at 3:00 pm
Hosted by the
Brain and Vision Research Laboratory