Isoflurane preferentially modulates synaptic responses to corticocortical stimulation over thalamocortical stimulation

Abstract Objective To test the effect of Isoflurane on synaptic transmission of cortico-cortical and thalamocortical projections to the auditory cortex, and investigate how it modulates cortical sensory information processing to produce unconsciousness. Methods Using murine auditory thalamocortical brain slices, afferent pathways from the medial geniculate body (MGB) and layer 1 of the proximal cortex were stimulated to evoke excitatory postsynaptic potentials (eEPSPs) in cortical neurons. Whole-cell recordings were made from pyramidal and fast-spiking neurons in layer 2/3 and layer 5. eEPSPs were evaluated along with intrinsic membrane properties in response to stimulation of both pathways with and without isoflurane. Results Isoflurane administration resulted in significant eEPSP amplitude reduction following stimulation of both thalamic and cortical pathways, in layer 2/3 (p=0.015, p