Alteration of electrical correlates of sensory processing by tetrahydrocannabinol.

The action of tetrahydrocannabinol on the function of four multimodality responsive neocortical areas was assessed in the cat. Cats, anesthetized with alpha-chloralose, were subjected to auditory, somatosensory, and two types of visual stimulation. Simultaneous evoked field potentials and multiple-unit activity were recorded.

Differential effects of lysergic acid diethylamide, methysergide, and cyproheptadine on modality-specific and nonspecific sensory evoked potentials.

The effects of lysergic acid diethylamide (LSD), methysergide, and cyproheptadine on activity in classical primary pathways of the visual and somatosensory systems were compared with their effects on activity in sensory convergent (association) regions in alpha-chloralose-anesthetized cats. Those effects were blocked by cyproheptadine whereas methysergide potentiated the actions of LSD on visual primary activity. In contrast, LSD depressed the primary somatic pathway, at small doses (25 to 50 micrograms/kg) and facilitated the response at larger doses (200 micrograms/kg).

Voltage threshold and excitability among variously sized cat hindlimb motoneurons.

Intracellular recording has been performed to examine whether any differences in apparent initial-segment voltage threshold exist between types F and S cat triceps surae motoneurons. Voltage threshold was estimated using orthodromic action potentials initiated by large, monosynaptic excitatory postsynaptic potentials (EPSPs) evoked by dorsal root stimulation. No significant differences in voltage threshold could be detected between types F and S motoneurons.

Slowing of cortical somatosensory evoked activity by delta 9-tetrahydrocannabinol and dimethylheptylpyran in alpha-chloralose-anesthetized cats.

Somatosensory and visual evoked potentials in the classical afferent primary pathways in cats anesthetized with alpha-chloralose were studied in order to characterize the effects of delta 9-tetrahydrocannabinol (THC) and the synthetic analog, dimethylheptylpyran (DMHP) on central sensory processing. THC and DMHP slowed primary cortical responses to radial nerve or ventralis posterolateralis (VPL) stimulation in a dose dependent manner. THC did not alter VPL activity evoked by radial nerve stimulation.