Graciela Mexicano

Sleep characteristics in the turkey Meleagris gallopavo

Electrophysiological and behavioral characteristics of the states of vigilance were analyzed in chronically implanted specimens of the turkey Meleagris gallopavo (M. gallopavo). Five different states of vigilance were observed throughout the nyctohemeral period: active wakefulness (AW), quiet wakefulness (QW), drowsiness (D), slow wave sleep (SWS) and rapid eye movement (REM) sleep. These states exhibit characteristics similar to those described in other bird species. Sleep periods displayed a polyphasic distribution; however, they showed the tendency to concentrate between 2100 and 0900 h in spite of the fact that the recordings were carried out under constant illumination. Sleep period occupied 45.71% of the nyctohemeral cycle, 43.33% corresponded to SWS, while 2.38% to REM sleep. The average duration of the REM sleep phase was very short, lasting 7.7+/-0.55 s (mean+/-S.D.). In contrast, its frequency was very high with an average recurrence of 268+/-63 phases throughout the nyctohemeral cycle. The short duration of REM sleep phase presented by the turkey as by other bird species studied up to now may be dependent upon genetic factors shared by this group of vertebrates.

Effect of p-chlorophenylalanine (PCPA) on sleep and monoamines content in the brain of a lizard species

Administration of PCPA, a specific inhibitor of serotonin synthesis, induced a significant decrease of total sleep time in the lizard Ctenosaura pectinata. This effect was exerted on both quiet sleep and active sleep, but it was more intense on active sleep. Reduction in the amount of active sleep was due to a decrease in the number of the episodes not in their mean duration, since this parameter increased significantly from 5.97 s, under control conditions, to 11.77 s, 10.66 s and 8.85 s at 24, 48 and 72 h after PCPA injection, respectively. Neurochemical analysis showed a significant decrease in the amount of serotonin in the analyzed brain stem structures 12 h after PCPA administration. The possible participation of serotonergic mechanisms in the regulation of reptilian sleep is discussed.

Effects of genital stimulation upon spinal reflex activity of female cats under various hormonal conditions.

Abstract Electrical responses to stimulation of either the medial gastrocnemius or the sural nerve were recorded from the L 7 ventral root in female spinal cats (C 1 - C 2 level). Experiments were performed in 7 intact, 10 ovariectomized, and 8 estradiol treated ovariectomized cats. Stimulation of the sural nerve elicited a two peaked polysynaptic response, and stimulation of the medial gastrocnemius nerve produced a monosynaptic response followed by a complex polysynaptic response. Tactile stimulation of the perivulvar skin area or the neck inhibited the polysynaptic response to both sural and medial gastrocnemius stimulation and facilitated the monosynaptic response to medial gastrocnemius stimulation. Vaginal and cervical stimulation inhibited the polysynaptic response induced by medial gastrocnemius stimulation. Enhancement of the monosynaptic response to medial gastrocnemius stimulation was noted at cessation of cervical stimulation. The effects obtained were independent of the endocrine condition of the animals. The responses here reported are probably related to the posture adopted by the female cat during coitus.

Interhemispheric changes in alpha rhythm related to time perception

Each cerebral hemisphere processes environmental information in a different but complementary manner. Structures located in the left hemisphere are assumed to participate in symbolic-logic thinking. Time perception may be considered among such thinking processes. The present study evaluates bilateral occipito-central EEG activity in healthy, right-handed subjects which was produced while they performed a visuomotor monitoring task. The task consisted of two stages. The first stage involved the subjects learning a fixed time interval (10 sec) and the measurement of their reaction time. Subjects responded to an isolated light stimulus by pressing a button with the dominant hand. In the second stage, the subjects accuracy in estimating interval-length was evaluated. Two forms of EEG analysis were used, frequency and alpha ratio, each of which was measured both prior to and subsequent to the motor response. A reversal group was used to carry out a complementary test. Subjects responded in the first block of experiments with the non-dominant (left) hand and with the dominant hand in the second. Results showed that left hemisphere activity was continuous during the interval-learning stage and with optimal reaction times and remained continuous when estimation values approximated the real interval. In addition, in optimal reaction time and near to optimal time estimation responses, the left side showed lower frequency and alpha ratio than did the right. Finally a progressive enhancement in both parameters from the right hemisphere was related to deterioration in test performance. Results from the reversal group did not differ from those of the first group. As evaluated by gross measurements of the EEG, a predominant participation of the left hemisphere in time processing is concluded.

Spike and wave complexes produced by four hallucinogenic compounds in the cat

The ability of four hallucinogenic compounds: ketamine, phencyclidine, quipazine and SKF-10,047 to produce spike and wave activity in the limbic system, was studied in cats with permanently implanted electrodes. Electronic frequency integrators were used to analyze the results and the percent of change in electrographic alterations was calculated. All the compounds studied, produced trains of 6/sec spike and waves complexes in the cingulum, rapid synchronous discharges in the amygdaloid complex, and slow wave synchronous activity and spiking in the septal areas. At low but hallucinatory concentrations of these drugs, the cortical EEG was not affected. Exploratory movements directed toward non-existent objects, classified as hallucinatory-like behavior, appeared simultaneous with these changes in the EEG recordings. It was concluded that there could exist a relationship between the appearance of 6/sec spike and wave complexes in the cingulum and the presence of hallucinations, produced by some synthetic drugs in the cat, this activity could be interpreted as the spreading of altered function of limbic and non-limbic nuclei related with this bundle which explain unspecificity of action.

Effect of a depleter of cerebral monoamines on sleep patterns of a chelonian reptile

Effect of reserpine administration on sleep patterns was studied in chronically implanted adult turtles Gopherus berlandieri. Four states of vigilance that differed behaviorally and electrophysiologically were observed: active wakefulness, quiet wakefulness, quiet sleep, and active sleep. Animals spent 88 and 2.92% of the nychthemeral cycle in quiet and active sleep, respectively. The active sleep phases were of short duration reaching a mean of 22 ± 6 sec (mean ± SD) and showing an occurrence of 124 ± 33 (mean ± SD) throughout the 24‐h period. High voltage spikes were observed during quiet sleep at a frequency of 37 ± 9 spikes/min (mean ± SD). Reserpine elicited a significant reduction in total sleep time and in the occurrence of high voltage spikes (P < 0.05). The number of active sleep episodes showed an important decrement throughout the nychthemeral cycle (P < 0.01). Our data provide electrophysiological and pharmacological evidence to support the analogy of reptilian and mammalian sleep. Drug Dev. Res. 39:115–120

Effect of oxcarbazepine on sleep architecture.

The most common side effects following administration of antiepileptic drugs involve alterations in sleep architecture and varying degrees of daytime sleepiness. Oxcarbazepine is a drug that is approved as monotherapy for the treatment of partial seizures and generalized tonic-clonic seizures. However, there is no information about its effects on sleep pattern organization; therefore, the objective of this work was to analyze such effects. Animals (Wistar rats) exhibited three different behavioral and electrophysiological states of vigilance: wakefulness, slow wave sleep (SWS), and rapid eye movement (REM) sleep. Oral treatment with oxcarbazepine (100 mg/kg) produced an increment in total sleep time throughout the recording period. This increment involved both SWS and REM sleep. Mean duration of the REM sleep phase was not affected. In contrast, the frequency of this sleep phase increased significantly across the 10-hour period. REM sleep latency shortened significantly. Results obtained in this work indicate that oxcarbazepines acute effects point to hypnotic properties.

Lateralization of spike and wave complexes produced by hallucinogenic compounds in the cat

The ability of four hallucinogenic compounds--ketamine, phencyclidine, quipazine, and SKF-10 047--to produce some specific electrical pattern in portions of the limbic system and the hemispheric lateralization of such effects were studied in cats with permanently implanted electrodes. Electronic frequency and area integrators were used to analyze the results, and the percentage change in electrographic alterations was calculated. All compounds studied produced trains of spike and wave complexes in the cingulum, rapid discharges in the amygdala complex, and slow-wave synchronous activity in the septal nucleus. Those changes predominated in the left hemisphere. At small but hallucinatory concentrations of these drugs, the cortical EEG was not affected. Exploratory movements directed toward nonexistent objects, classified as hallucinatory-like behavior, appeared simultaneous with these changes in the EEG recordings. We concluded that there could exist a relationship between the appearance of spike and wave complexes in the limbic system without epileptic signs (twitching or myoclonus) and the presence of hallucinations, and that there is a left side hemispheric lateralization of the electrographic effects, viewing cerebral dominance phenomena as a functional and fluctuating state.

Sleep Characteristics in Blind Subjects

The sleep patterns of ten blind adults and their matched controls were studied during three consecutive nights. The first night was allowed for adaptation. Significant electroencephalographic and quantitative findings were obtained from nights 2 and 3. Although alpha-like rhythm was registered in only one blind subject during wakefulness, it was displayed by 8 of the 10 blind participants of this study during REM sleep. This rhythm was also present during the N2 sleep stage. The delta phase of sleep was markedly reduced as compared to the healthy subjects. Mean duration of REM sleep episodes was significantly longer in blind subjects; in contrast, their frequency was lower than in the corresponding control subjects. Total sleep time and sleep efficiency was noticeably shorter in blind subjects. Atypical brain activity and quantitative sleep abnormalities found in the blind subjects may be explained on the basis of degeneration of cerebral organization and circadian rhythm alterations induced by absence of visual stimulation.

Projections of the Nucleus Accumbens in the Cat

Abstract: Due to the recent advances in knowledge on the function of the limbic sys tem it would be wise to consider this system as being widely distributed throughout the diencephalic and mesencephalic levels as well as the forebrain. Numerous regions have been discovered that are related to the limbic structures in anatomical and functional respects. According to Koikegami et al. (1967), it would be adequate to divide this system into two main categories–the major limbic rim or the structure proper and the paralimbic structures. The former defined phylogenetically and ontogenetically as those structures around the third ventricle such as: the hippocampus, septum, dentate gyrus, fimbria hippocampi, anterior and posterior cingulate gyri, area paraolfactoria, amygdala and Diagonal Band of Broca.