Chapter 17 Intraoperative recording of the very fast oscillatory activities evoked by median nerve stimulation in the human thalamus

Publisher Summary This chapter characterizes thalamic very fast oscillations (VFOs) and their relationship with thalamic neuronal firing. VFOs at a frequency of 500–700 Hz are superimposed on scalp-recorded cortical potentials from the human sensory cortex (S1). VFOs have also been observed as small notches superimposed on positive SEPs recorded with electrodes in the human thalamus. In the chapter, microstimulation is performed at regular intervals and perceptual and/or motor effects are determined. This strategy allowed a physiological map to be constructed relative to the imaged coordinates. The recorded VFOs showed phase reversal at the anterior commisure (AC)–posterior commisure (PC) line and their amplitudes were largest near the AC–PC line. Tactile neuron firing was closely correlated with VFOs. The chapter suggests that either VFOs may determine the exact time of neuron firing in ventrocaudal nucleus (Vc) or that Vc neuron firing is somehow time-locked in a repetitive pattern, giving rise to oscillatory VFO.