Wideband phase locking to modulated whisker vibration point to a temporal code for texture in the rat's barrel cortex.

Rats probe objects with their whiskers and make decisions about sizes, shapes, textures and distances within a few tens of milliseconds. This perceptual analysis requires the processing of tactile high-frequency object components reflecting surface roughness. We have shown that neurons in the barrel cortex of rats encode high-frequency sinusoidal vibrations of whiskers for sustained periods when presented with constant amplitudes and frequencies.

High-frequency whisker vibration is encoded by phase-locked responses of neurons in the rat's barrel cortex.

Rats perform texture discrimination during tactile exploration with their whiskers with high spatial and temporal precision. Although the peripheral mechanoreceptors provide tactile information with exquisite temporal resolution, physiological studies have suggested that this information might be lost at the cortical level. To address this discrepancy, multiunit and single-unit recordings were performed in the barrel cortex of isoflurane-anesthetized rats using continuous sinusoidal vibration of single whiskers at 15-700 Hz.

Corresponding minimum alveolar concentrations of isoflurane and isoflurane/nitrous oxide have divergent effects on thalamic nociceptive signalling.

Background: Suppression of nociceptive signalling in the thalamus is considered to contribute significantly to the anaesthetic state. Assuming additivity of anaesthetic mixtures, our study assessed the effects of corresponding minimum alveolar concentrations (MACs) of isoflurane and isoflurane/nitrous oxide on thalamic nociceptive signalling.

Methods: Nociceptive response activity (elicited by controlled radiant heat stimuli applied to cutaneous receptive fields) of single thalamic neurons was compared in rats anaesthetized at approximately 1.

Contributions of GABAergic and glutamatergic mechanisms to isoflurane-induced suppression of thalamic somatosensory information transfer.

Indications for a pivotal role of the thalamocortical network in producing the state of anesthesia have come from in vivo animal studies as well as imaging studies in humans. We studied possible synaptic mechanisms of anesthesia-induced suppression of touch perception in the rat's thalamus. Thalamocortical relay neurons (TCNs) receive ascending and descending glutamatergic excitatory inputs via NMDA and non-NMDA receptors (AMPAR) and are subjected to GABA(A)ergic inhibitory input which shapes the sensory information conveyed to the cortex.

Temporal shaping of phasic neuronal responses by GABA- and non-GABA-mediated mechanisms in the somatosensory thalamus of the rat.

Trapezoidal mechanical movement of whiskers was used to study the responses of 44 single thalamic ventral posteromedial (VPM) neurons to dynamic and static stimulus components in urethane-anesthetized rats. The effects of local administration of the GABAA receptor antagonist, bicuculline, and the GABAB receptor antagonist, 2-hydroxysaclofen, were tested to determine whether and to what extent the responses altered when GABA-mediated inhibitory synaptic transmission was blocked. Two classes of phasically responding neurons were identified, ON/OFF and movement-sensitive types.