Distinct α- and β-band rhythms over rat somatosensory cortex with similar properties as in humans

J Neurophysiol. 2016 Jun 1;115(6):3030-44. doi: 10.1152/jn.00507.2015. Epub 2016 Mar 23.

Abstract

We demonstrate distinct α- (7-14 Hz) and β-band (15-30 Hz) rhythms in rat somatosensory cortex in vivo using epidural electrocorticography recordings. Moreover, we show in rats that a genuine β-rhythm coexists alongside β-activity that reflects the second harmonic of the arch-shaped somatosensory α-rhythm. This demonstration of a genuine somatosensory β-rhythm depends on a novel quantification of neuronal oscillations that is based on their rhythmic nature: lagged coherence. Using lagged coherence, we provide two lines of evidence that this somatosensory β-rhythm is distinct from the second harmonic of the arch-shaped α-rhythm. The first is based on the rhythms' spatial properties: the α- and β-rhythms are demonstrated to have significantly different topographies. The second is based on the rhythms' temporal properties: the lagged phase-phase coupling between the α- and β-rhythms is demonstrated to be significantly less than would be expected if both reflected a single underlying nonsinusoidal rhythm. Finally, we demonstrate that 1) the lagged coherence spectrum is consistent between signals from rat and human somatosensory cortex; and 2) a tactile stimulus has the same effect on the somatosensory α- and β-rhythms in both rats and humans, namely suppressing them. Thus we not only provide evidence for the existence of genuine α- and β-rhythms in rat somatosensory cortex, but also for their homology to the primate sensorimotor α- and β-rhythms.

Keywords: barrel cortex; sensorimotor oscillations; somatosensory cortex; β-rhythm; μ-rhythm.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials / physiology*
  • Alpha Rhythm / physiology*
  • Animals
  • Beta Rhythm / physiology*
  • Brain Mapping*
  • Electrocorticography
  • Electrodes
  • Female
  • Fourier Analysis
  • Humans
  • Male
  • Periodicity
  • Physical Stimulation
  • Rats
  • Rats, Long-Evans
  • Somatosensory Cortex / physiology*
  • Touch