420 Task Related Physiology of the Dentalothalamocortical Circuit in Naïve and Stroke Rats

Abstract

INTRODUCTION: As stroke mortality has declined, a growing number of patients are left with chronic, residual post-stroke hemiparesis. Targeted, neurostimulation-based upregulation of activity of the dentatothalamocortical (DTC) pathway, a disynaptic pathway with net excitatory effects on widespread areas of the cerebral cortex, has been proposed previously as a potential approach to enhance cortical excitability in surviving, perilesional cortical regions and promote motor rehabilitation after a stroke. METHODS: 13 rats (7 naÏve and 6 stroke) were implanted unilaterally with a 9 channel recording electrode in the DN (ipsilateral to dominate forepaw) and cortical EEG screws (contralateral to dominate forepaw) were placed over the perilesional area. LFPs were recorded from the DN and motor cortex during a reach/pull task for 4 weeks after surgery. RESULTS: At a 25g force threshold, DN LFPs were diminished in the 8-12 hz in the pre-movement and movement phase in stroke rats compared with naÏve rats. At a 5g force threshold, 8-12 hz LFPs in the DN were significantly diminished in the stroke animals relative to naive during the pre-movement and movement phase (p < .05). At a 50g force threshold, cortical 1.5-4 hz oscillations were significantly diminished during the pre-movement and movement phase in stroke rats compared to naÏve rats (p < .05). CONCLUSION: Diminished 8-12 hz reach-related LFP activity in the DN of stroke rats relative to naÏve rats during the pre-movement and movement phase of a reaching task, may function as a potential predefined trigger for the onset of deep brain stimulation as a therapeutic intervention to promote motor rehabilitation for chronic post-stroke hemiparesis.