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

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.

Download Full-text

Recording High Frequency Neural Signals Using Conformable and Low-Impedance ECoG Electrodes Arrays Coated with PEDOT-PSS-PEG

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.102.77 ◽

2016 ◽

Vol 102 ◽

pp. 77-85 ◽

Cited By ~ 2

Author(s):

Elisa Castagnola ◽

Marco Marrani ◽

Emma Maggiolini ◽

Francesco Maita ◽

Luca Pazzini ◽

...

Keyword(s):

Somatosensory Cortex ◽

High Frequency ◽

Cortical Neurons ◽

Ad Hoc ◽

Ionic Conductivities ◽

Neural Signals ◽

Brain Surface ◽

Small Neuron ◽

Rat Somatosensory Cortex

Electrocorticography (ECoG) is receiving growing attention for both clinical and research applications thanks to its reduced invasiveness and ability of addressing large cortical areas. These benefits come with a main drawback, i.e. a limited frequency bandwidth. However, recent studies have shown that spiking activity from cortical neurons can be recorded when the ECoG grids present the following combined properties: (I) conformable substrate, (II) small neuron-sized electrodes with (III) low-impedance interfaces. We introduce here an ad-hoc designed ECoG device for investigating how electrode size, interface material composition and electrochemical properties affect the capability to record evoked and spontaneous neural signals from the rat somatosensory cortex and influence the ability to record high frequency neural signal components.Contact diameter reduction down to 8 μm was possible thanks to a specific coating of a (3,4-ethylenedioxytiophene)-poly (styrenesulfonate)-poly-(ethyleneglycol) (PEDOT-PSS-PEG) composite that drastically reduces impedance and increases electrical and ionic conductivities. In addition, the extreme thinness of the polyimide substrate (6 - 8 μm) and the presence of multiple perforations through the device ensure an effective contact with the brain surface and the free flow of cerebrospinal fluid. In-vivo validation was performed on rat somatosensory cortex.

Download Full-text

Effects of Ventrobasal Lesion and Cortical Cooling on Fast Oscillations (>200 Hz) in Rat Somatosensory Cortex

Journal of Neurophysiology ◽

10.1152/jn.01098.2002 ◽

2003 ◽

Vol 89 (5) ◽

pp. 2380-2388 ◽

Cited By ~ 13

Author(s):

Richard J. Staba ◽

Barbara Brett-Green ◽

Marcy Paulsen ◽

Daniel S. Barth

Keyword(s):

Somatosensory Cortex ◽

Oscillatory Activity ◽

Electrode Arrays ◽

Subcortical Structures ◽

Ventrobasal Thalamus ◽

Before And After ◽

Cortical Cooling ◽

Rat Somatosensory Cortex ◽

Fast Oscillations

High-frequency oscillatory activity (>200 Hz) termed “fast oscillations” (FO) have been recorded in the rodent somatosensory cortex and may reflect very rapid integration of vibrissal information in sensory cortex. Yet, while electrophysiological correlates suggest that FO is generated within intracortical networks, contributions of subcortical structures along the trigeminal pathway remain uncertain. Using surface and laminar electrode arrays, in vivo recordings of vibrissal and electrically evoked FO were made within somatosensory cortex of anesthetized rodents before and after ablation of the ventrobasal thalamus (VB) or during reversible cortical cooling. In VB-lesioned animals, vibrissal stimulation failed to evoke FO, while epicortical stimulation in lesioned animals remained effective in generating FO. In nonlesioned animals, cortical cooling eliminated vibrissal-evoked FO despite the persistence of thalamocortical input. Vibrissal-evoked FO returned with the return to physiological temperatures. Results from this study indicate that somatosensory cortex alone is able to initiate and sustain FO. Moreover, these data suggest that cortical network interactions are solely responsible for the generation of FO, while synchronized thalamocortical input serves as the afferent trigger.

Download Full-text

Intracellular Correlates of Fast (>200 Hz) Electrical Oscillations in Rat Somatosensory Cortex

Journal of Neurophysiology ◽

10.1152/jn.2000.84.3.1505 ◽

2000 ◽

Vol 84 (3) ◽

pp. 1505-1518 ◽

Cited By ~ 121

Author(s):

Michael S. Jones ◽

Kurt D. MacDonald ◽

ByungJu Choi ◽

F. Edward Dudek ◽

Daniel S. Barth

Keyword(s):

Action Potential ◽

Somatosensory Cortex ◽

Field Potential ◽

Oscillatory Activity ◽

Cellular Events ◽

Recurrent Activity ◽

Potential Recording ◽

Rat Somatosensory Cortex ◽

Fast Oscillations

Oscillatory activity in excess of several hundred hertz has been observed in somatosensory evoked potentials (SEP) recorded in both humans and animals and is attracting increasing interest regarding its role in brain function. Currently, however, little is known about the cellular events underlying these oscillations. The present study employed simultaneous in-vivo intracellular and epipial field-potential recording to investigate the cellular correlates of fast oscillations in rat somatosensory cortex evoked by vibrissa stimulation. Two distinct types of fast oscillations were observed, here termed “fast oscillations” (FO) (200–400 Hz) and “very fast oscillations” (VFO) (400–600 Hz). FO coincided with the earliest slow-wave components of the SEP whereas VFO typically were later and of smaller amplitude. Regular spiking (RS) cells exhibited vibrissa-evoked responses associated with one or both types of fast oscillations and consisted of combinations of spike and/or subthreshold events that, when superimposed across trials, clustered at latencies separated by successive cycles of FO or VFO activity, or a combination of both. Fast spiking (FS) cells responded to vibrissae stimulation with bursts of action potentials that closely approximated the periodicity of the surface VFO. No cells were encountered that produced action potential bursts related to FO activity in an analogous fashion. We propose that fast oscillations define preferred latencies for action potential generation in cortical RS cells, with VFO generated by inhibitory interneurons and FO reflecting both sequential and recurrent activity of stations in the cortical lamina.

Download Full-text