Serotonergic neurons in the brainstem modulate animal hypnosis

Activity of rabbit neocortex and hippocampus neurons in orientational-investigative behavior and freezing

Autocorrelation histograms were used to study the nature of spike activity in neurons recorded bilaterally from the visual and parietal areas of the cortex and hippocampal field CA1 in rabbits in free behavior during exposure to emotionally significant stimuli. Active movement orientational-investigative reactions to stimuli were associated with grouping of discharges and periodicity in the spike activity of most neurons in the cortex and hippocampus, this being dominated by the theta frequency (predominantly 4-5 Hz in the cortex and 4-5 and 6-7 Hz in the hippocampus). As compared with active movement reactions, freezing in response to stimulation was associated with increased numbers of neurons with uniform discharge distributions, while the spike activity of neurons with discharge periodicity showed increases in the intensity of the delta frequency (predominantly from 2 to 4 Hz), while theta intensity decreased. The number of neurons with periodic frequency in the delta range was greater in freezing than in the baseline state of calmly sitting rabbits.

Effect of hypnotic sedation during percutaneous transluminal coronary angioplasty on myocardial ischemia and cardiac sympathetic drive

Forty-six patients were randomized to receive drug (group 1) or hypnotic sedation (group 2) during percutaneous transluminal coronary angioplasty of the left anterior descending coronary artery. Intracoronary and standard electrocardiograms were continuously registered, and heart rate spectral variability was studied. Normalized units of low- and high-frequency components and the ratio of low to high frequency were measured during balloon inflations. The ST segment shifted at the first balloon inflation from 0.02 +/- 0.01 to 0.09 +/- 0.6 mm in group 1 and from 0.02 +/- 0.08 to 0.1 +/- 0.6 in group 2 mm (p <0.05). In group 1, the low-frequency band and the ratio of low to high frequency increased significantly during the first balloon inflation (from 59 +/- 10 to 75 +/- 10 normalized units and from 2.4 +/- 1.4 to 7.3 +/- 4.7, respectively; p <0.001). The increase of the ratio of low to high frequency was significantly related to ST shift (r = 0.706; p <0.01). In contrast, no significant variation of spectral parameters was found in group 2. The increase in cardiac sympathetic activity associated with balloon inflation and myocardial ischemia during percutaneous transluminal coronary angioplasty of the left anterior descending coronary artery was selectively eliminated by hypnosis but not by drug sedation.

Comparative analysis of the frequency of neuron spike activity in the sensorimotor cortex of the right and left hemispheres in conditions of immobilization catatonia in rabbits

Multineuron activity was recorded from the sensorimotor cortex of the right and left hemispheres during immobilization catatonia in rabbits. The first session of immobilization of the animals was followed by changes in spike frequency in 47% of neurons in the sensorimotor cortex of the right hemisphere. Of these, 30% showed decreases in spike frequency and 17% showed increases. Spike frequency in the sensorimotor cortex of the left hemisphere changed in only 18% of cells, of which 13% showed decreases in spike frequency and 5% showed increases. The spike frequency of neighboring (recorded with the same electrode) neurons could change reciprocally. Differences in neuron activity in the two hemispheres were virtually absent after the second session of immobilization (several days after the first)--spike activity changed in 21% of neurons in the right hemisphere and 24% in the left hemisphere. The ratios of the numbers of neurons with increases and decreases in spike activity in "hypnosis" also became identical in the cortex of the right and left hemispheres. A hypothesis is proposed for the involvement of cortical neurons in the organization of "hypnosis-like" states.