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

Abstract

Fransen AM, Dimitriadis G, van Ede F, Maris E. Distinct ␣-and ␤-band rhythms over rat somatosensory cortex with similar properties as in humans. J Neurophysiol 115: 3030 -3044, 2016. First published March 23, 2016 doi:10.1152/jn.00507.2015.-We demonstrate distinct ␣-(7-14 Hz) and ␤-band (15-30 Hz) rhythms in rat somatosensory cortex in vivo using epidural electrocorticography recordings. Moreover, we show in rats that a genuine ␤-rhythm coexists alongside ␤-activity that reflects the second harmonic of the arch-shaped somatosensory ␣-rhythm. This demonstration of a genuine somatosensory ␤-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 ␤-rhythm is distinct from the second harmonic of the archshaped ␣-rhythm. The first is based on the rhythms' spatial properties: the ␣-and ␤-rhythms are demonstrated to have significantly different topographies. The second is based on the rhythms' temporal properties: the lagged phase-phase coupling between the ␣-and ␤-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 ␣-and ␤-rhythms in both rats and humans, namely suppressing them. Thus we not only provide evidence for the existence of genuine ␣-and ␤-rhythms in rat somatosensory cortex, but also for their homology to the primate sensorimotor ␣-and ␤-rhythms.

The Development of Nociceptive Network Activity in the Somatosensory Cortex of Freely Moving Rat Pups

“…Nevertheless, homologous brain rhythms have been recorded in the adult rat, primate, and human somatosensory cortex (Fransen et al 2016). Using comparative anatomical data, the P14 rat cortex has been proposed to be equivalent to that of a 29-week gestation human infant (Clancy et al 2001), while a more recent algorithm, based on the maturation of visual cortical synaptic proteins, suggests that a P11 rat pup is equivalent to a term human infant (Pinto et al 2015).…”

Pulsed Facilitation of Corticospinal Excitability by the Sensorimotor μ-Alpha Rhythm

“…Sensorimotor -alpha and -beta rhythms are physiologically and functionally separate rhythms that fluctuate independently (McFarland et al, 2000;Fransen et al, 2016;Stolk et al, 2019), and whereas beta was not investigated during this -alpha focused investigation, its precentral origin and clear motor taskrelated modulation make it a strong candidate for exerting power-and phase-specific effects on corticospinal excitability. However, in our previous studies we could not identify any such effects of beta by means of post hoc analyses, neither with respect to phase nor power (Thies et al, 2018), and real-time beta-triggered TMS may be needed to answer that question in the future.…”

When brain rhythms aren't ‘rhythmic’: implication for their mechanisms and meaning

“…In this vein, Fransen et al, 2015 have proposed a new method to define rhythmicity based on repeatability of activity in adjacent time windows, termed lagged coherence. They applied this measure to distinguish separable alpha and beta components of the somatosensory mu rhythm [62*,63]. …”