Diurnal variation and distribution of grooming behavior in captive common marmoset families (Callithrix jacchus)

Grooming is an important social activity among primates. In an investigation of its diurnal distribution, all grooming episodes (self-and allo-) were recorded in three families of captive common marmosets (Callithrix jacchus) kept under natural environmental conditions at hourly intervals for periods of 20 min from 05:00 to 18:00 h, for three consecutive days a week for four weeks. The three families were composed of a reproductive pair and their offspring, with 8, 8 and 7 individuals, respectively. No significant variations were detected within families in terms of days or weeks. However, one family did perform more grooming than the others. The frequency of grooming episodes per hour/per family was higher during the period from 08:00-12:00 h, with acrophases narrowly distributed near 10:00 h, (Family 1 = 10:32 ñ 00:33 h; Family 2 = 10:11 ñ 00:13 h; Family 3 = 09:45 ñ 00:14 h) and lower frequencies were observed at the beginning and end of the active period. The differences between families are probably related to the social dynamics of the individual groups and not to their size

Correlations between morningness-eveningness character, sleep habits and temperature rhythm adolescents

The correlations between morningness-eveningness character (Horne & Ostberg score), sleep habits and temperature acrophase of 62 adolescents (mean age 13 years and 6 months) were investigated on three occasions at 6-month intervals. Home & Ostberg scores ranged from 29 to 74 with a similar distribution on the three occasions. Temperature acrophase mode occurred around 15:00 p.m. Earlier sleep onset time and wake-up time and earlier temperature acrophase were associated with morningness. The more evening type the adolescent was, the shorter was the sleep lengh on schools days and the longer was the sleep length on non-school days. Correlations between temperature acrophase and morningness-eveningness character were found in a subgroup of adolescents and require further confirmation. The correlations between morningness-eveningness and sleep habits were present on the three occasions investigated, indicating that these are stable correlations and that morningness-eveningness questionnaires can provide suitable information for studies of this age group

Remarkable similarities between the temporal organization of neocortical electrographic sleep patterns of rats and humans

Electrocorticographic activity was automatically recorded in albino rats for 72 consecutive h and analyzed by procedures suitable to detect 24-h rhythms. Beta (alert wakefulness), theta (somnolence), delta (slow wave sleep) and sigma 1 (superficial synchronized sleep) activities showed a robust circadian rhythmic distribution. The acrophases (maxima of the adjusted cosine curve) occurred at 23:39, 07:59, 08:37 and 13:25 h, respectively. EMG atonia and extreme hypotonia (less than 10% of mean EMG level) episodes showed a 24-h rhythm peaking at 14:18 h. The temporal sequence within the circadian rest period, i.e., somnolence, slow, wave sleep, superficial synchronized sleep and paradoxical sleep, is very similar to that known to occur during the nocturnal sleep of humans

Lack of similarity between the effect of lesions of the suprachcasmatic nucleus and subparaventricular hypothalamic zone on behavioral circadian rhythms

Rats were submitted to eletrolytic lesion of either the suprachiasmatic nucleus (SCN) or the subparaventricular hypothalamic zone (SPVH) and the effects on circadian behavioral rhythms were compared. While the SCN lesion abolished the circadian rythmicity of all behavioral patterns, the SPVH lesion only abolished that of the eating and drinking behavior and reduced the amplitude of a behavioral item usually associated with REM sleep