Frequency-Specific Coupling in the Cortico-Cerebellar Auditory System

1 Department of the Neurosciences, Centre for Applied Medical Research, University of Navarra School of Medicine, Pamplona, Spain; and 2 Wellcome Department of Imaging Neuroscience, Institute of Neurology, University College of London, London, United Kingdom Submitted 31 July 2008; accepted in final form 31 July 2008 Induced oscillatory activity in the auditory cortex peaks at around 40 Hz in humans. Using regional cerebral blood flow and positron emission tomography we previously confirmed frequency-selective cortical responses to 40-Hz tones in auditory primary cortices and concomitant bilateral activation of the cerebellar hemispheres. In this study, using functional magnetic resonance imaging (fMRI) we estimated the influence of 40-Hz auditory stimulation on the coupling between auditory cortex and superior temporal sulcus (STS) and Crus II, using a dynamic causal model of the interactions between medial geniculate nuclei, auditory superior temporal gyrus (STG)/STS, and the cerebellar Crus II auditory region. Specifically, we tested the hypothesis that 40-Hz-selective responses in the cerebellar Crus II auditory region could be explained by frequency-specific enabling of interactions in the auditory cortico–cerebellar–thalamic loop. Our model comparison results suggest that input from auditory STG/STS to cerebellum is enhanced selectively at gamma-band frequencies around 40 Hz. Address for reprint requests and other correspondence: M. A. Pastor, Centre for Applied Medical Research, Department of the Neurosciences, University of Navarra School of Medicine, CUN, 31080 Pamplona, Spain (E-mail: mapastor{at}unav.es )