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Abstract #0661

Cortical & Thalamic Sensory Responses in Rat Brain by fMRI and Neurophysiology

Basavaraju G. Sanganahalli1, Peter Herman1, Douglas L. Rothman1, 2, Hal Blumenfeld3, Fahmeed Hyder1, 2

1Diagnostic Radiology, Yale University, New haven, CT, United States; 2Biomedical Engineering, Yale University; 3Neurology, Yale University, New Haven

Peripheral electrical stimulation (2mA, 0.3ms, variable frequencies 1-48Hz) of the rat forepaw evoked a positive BOLD signal change in the contralateral cortical (S1FL) and ventral posterior nucleus (VPL) of thalamus under different anesthetics (Isoflurane, Domitor and α-chloralose). The BOLD responses were correlated with neural activities. However both fMRI and neuronal responses exhibited a different frequency tuning curve for each anesthetic in the (S1FL), while the same linear frequency response in VPL was elicited in all anesthetic conditions. These results suggest that subcortical structure is less influenced by anesthesia, while in the cortex the deeper anesthesia augments the process of adaptation.