Mechanisms and functions of human neocortical rhythms in sensory perception
Stephanie Jones (May 10, 2013)
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Low frequency neocortical rhythms are among the most prominent activity measured in human brain imaging signals such as electro- and magneto-encephalography (EEG/MEG). Elucidating the role that these dynamics play in perception, cognition and action is a key challenge of modern neuroscience. We have recently combined human brain imaging, computational neural modeling, and electrophysiological recordings in rodents to explore the functional relevance and mechanistic underpinnings of rhythms in primary somatosensory cortex (SI), containing Alpha (7-14Hz) and Beta (15-29Hz) components. In this talk, I will review our findings showing this rhythm impacts tactile detection, changes with healthy aging and practice, and is modulated with attention. Constrained by the human imaging data, our biophysically principled computational modeling work has led to a novel prediction on the origin of this rhythm predicting that it emerges from the combination of two stochastic ~10 Hz thalamic drives to the granular/infragranular and supragranular cortical layers. Relative Alpha/Beta expression depends on the strength and delay between the thalamic drives. This model is able to accurately reproduce numerous key features of the human rhythm and proposes a specific mechanistic link between the Beta component of the rhythm and sensory perception. Further, initial electrophysiological recordings in rodents support out hypotheses and suggest a role for non-lemniscal pallidal thalamus in coordinating Beta rhythmicity, with relevance to understanding disrupt Beta in Parkinson's Disease.