Circadian variations of performances and basic rhythms

Difficulties with chronopsychology studies include a masking effect of variables, the combination of different rhythms and variations of strategies. An experiment is conducted to analyze the role of circadian variations of elementary processes in the variations of performance for a complex task. Twenty-four subjects solved anagrams and tried to find the rule of anagram construction, during two sessions, at 10 am and 5 pm. Responses were classified in three groups: (a) discovery of the anagram construction rule (R2 responses); (b) resolution of anagram without discovery of rule (R1 responses); (c) failure, no resolution of anagram (R0 responses). During the second session, R2 performances were better at 10 am than at 5 pm. In contrast, R1 performances were better at 5 pm than at 10 am. Rule application was faster at 10 am than at 5 pm. Results are discussed in terms of variations of short-term memory capacity (Folkard and Monk, 1980). Using chronopsychology to analyze the role of elementary processes in a complex task is discussed.     

Circadian rhythms and partial recovery of regulatory drinking in rats after lateral hypothalamic lesions.

Rats that had recovered spontaneous ingestive behavior after lesions of the lateral hypothalamus were challenged with acute injections of hypertonic NaCl administered at different times during the day/night cycle. Following these injections, drinking was observed only during the nighttime. After morning injections the rats frequently waited until nightfall before drinking, whereas animals injected at night showed much shorter delays in the behavioral response; a similar nocturnal predominance of drinking was seen after food deprivation and in the ad-lib situation. Studies in blinded animals suggested that these effects were due to an endogenous circadian rhythm.     

Circadian rhythms determined by cosine curve fitting: Analysis of continuous work and sleep-loss data

In this study, we report the effects of sleep loss upon circadian rhythm parameters analyzed by the cosine curve fitting (cosinor) method. Rhythm alterations are described as reductions in rhythm strength, increases in individual variations producing an increase in the 95% confidence limits, and reductions in rhythm amplitude. Subjects worked continuously at tasks for 45 h with time-of-day cues. Circadian cycles in physiological and mood variables remained intact, but rhythms in some task performance measures no longer showed significant 24-h/cycle activities. The relationship between oral temperature, mood, and pulse rhythms continued undisturbed during the continuous work period; however, the performance linkage to oral temperature was lost. These findings direct attention to individual difference in susceptibility to continuous work periods and suggest that 24-h rhythms in some performance and physiological measures perhaps are more readily responsive to an altered wake/sleep cycle than other circadian rhythms.     

Circadian rhythms in executive function during the transition to adolescence: the effect of synchrony between chronotype and time of day

To explore the influence of circadian rhythms on executive function during early adolescence, we administered a battery of executive function measures (including a Go-Nogo task, the Iowa Gambling Task, a Self-ordered Pointing task, and an Intra/Extradimensional Shift task) to Morning-preference and Evening-preference participants (N = 80) between the ages of 11 and 14 years who were tested in the morning or afternoon. Significant Chronotype × Time of Day interactions (controlling for amount of sleep the previous night) revealed that adolescents tested at their optimal times of day performed better than those tested at their nonoptimal times. Implications for our understanding of physiological arousal, sleep, and executive function during adolescence are discussed.     

Sleep-wakefulness rhythms in the rabbit

The characteristics and stability of sleep-wakefulness patterns across consecutive 24-h periods were examined in adult male rabbits implanted for chronic recording of electroencephalographic, eye movement, and nuchal muscle activities. Criteria for stage scoring along with associated scoring reliability are presented. Rabbits slept an average of 11.4 h per day, 25.9% of which was drowsy, 64.5% slow wave sleep, and 9.6% paradoxical sleep. Diurnal differences in amount and type of sleep, consisting of increased wakefulness and decreased paradoxical sleep during the dark phase of the light-dark cycle, were observed. The results are integrated with those of previous sleep studies in this species and phylogenetic implications of variations in the distribution and characteristics of sleep in the rabbit are discussed.     

Seven-minute rhythms in stable avoidance conditioning

Investigation of the “inextinguishable” locomotor avoidance reflex revealed periodic oscillating of reaction times, motor reaction times, and latent periods, when the conditional stimuli were applied every half minute. These rhythmic properties were verified by autocorrelation. Frequency distribution of all significant wavelengths occurring in rhythmic processes of stabilized conditioning showed seven-minute wavelengths for the most part and smaller numbers of wavelengths of 5 to 9 and 14 minutes. A significant number of wavelengths of 3.5 minutes was not seen. Locomotor avoidance conditioning permitted separate automatic registration of reaction times and motor reaction times. The two values showed synchronous periodic courses in stabilized conditioning, with the motor reaction times being longer. The periodicities found, thought to be due to controlling processes in the central nervous system, can be explained in either or both of two ways: the periodic courses represent a frequency range of a structured time mechanism in the sense of a “clock inherent in an organism”; the rhythms of conditional processes represent an adaptation mechanism in organism-environment interrelations. It can be assumed that the two mechnanisms work synergistically.     

Circadian time perception

The variability of anticipating a meal was investigated. Sprague-Dawley rats earned food by inspecting a food source during a 3-hr interval. Food was not available at other times. In Experiment 1, the meal started 3 or 7 hr after light offset in a 12-hr light-dark cycle. Experiment 2 was conducted in constant darkness with 14-, 22-, 22.5-, 24-, 25.5-, 26-, or 34-hr intermeal intervals. Inspections increased before the meal. Rats timed intervals in the circadian range (22-26 hr) with lower variability than that for intervals outside this range (3-14 and 34 hr). Higher precision in timing selected intervals violates the scalar property. Proximity to a circadian oscillator improves timing precision. Variability may be used to identify oscillators with noncircadian periods.     

From biological rhythms to social rhythms: Physiological precursors of mother-infant synchrony

Links between neonatal biological rhythms and the emergence of interaction rhythms were examined in 3 groups (N = 71): high-risk preterms (HR; birth weight <1,000 g), low-risk preterms (LR; birth weight =1,700-1,850 g), and full-term (FT) infants. Once a week for premature infants and on the 2nd day for FT infants, sleep-wake cyclicity was extracted from 4-hr observations and cardiac vagal tone was measured. At term age, infant orientation was tested with the Neonatal Behavior Assessment Scale. At 3 months, arousal modulation and emotion regulation were assessed, and mother-infant synchrony was computed from microanalysis of face-to-face interactions using time-series analysis. Sleep-wake amplitudes showed a developmental leap at 31 weeks gestation, followed by a shift in vagal tone at 34 weeks gestation. At term, differences among FT, LR, and HR infants were observed for biological rhythms in a linear-decline pattern. Sleep-wake cyclicity, vagal tone, newborn orientation, and arousal modulation were each uniquely predictive of mother-infant synchrony. The organization of physiological oscillators appears to lay the foundation for the infant's capacity to partake in a temporally matched social dialogue.     

Modality differences in short-term memory for rhythms

Prior research has established that performance in short-term memory tasks using auditory rhythmic stimuli is frequently superior to that in tasks using visual stimuli. In five experiments, the reasons for this were explored further. In a same-different task, pairs of brief rhythms were presented in which each rhythm was visual or auditory, resulting in two same-modality conditions and two cross-modality conditions. Three different rates of presentation were used. The results supported the temporal advantage of the auditory modality in short-term memory, which was quite robust at the quickest presentation rates. This advantage tended to decay as the presentation rate was slowed down, consistent with the view that, with time, the temporal patterns were being recoded into a more generic form.     

Ultradian rhythms of gastric acidity

Measurements of gastric pH and hydrogen ion concentration were made serially for six hours in five rhesus monkeys. Both pH and hydrogen ion concentration showed rapid fluctuations with periods approximating 90 minutes. These rhythms persisted in the face of continous infusion with Pentagastrin, indicating that while gastrin release is sufficient to stimulate acid secretion, it is not the only mechanism of acid control.     

Vigilance ratios implicate biological rhythms

Vigilance research has been focused on differences, yet ratios might have intrinsic, numerical significance. Reanalysis of data from Watkins' 1963 psychophysical experiment and 49 vigilance reports showed that individual and group ratios, including errors or misses: detections, were related to roots (particularly of base 1/12 and multiples), powers, e-base ratios (EBR), and fractions. Examples are given from well-known experiments of remarkably exact relationships between conditions, time periods, etc. It is suggested that these phenomena are the product of biological rhythms. Theoretical implications are briefly discussed and the advantages of ratio analysis noted, as when this method proved that criterion beta changes, given as nonsignificant, formed part of an ordered set. In a real-world application, the frequency of lane-drifts in O'Hanlon and Kelly's 1977 report is shown to follow a mathematical pattern.     

Servo control of behavior rhythms

A laboratory computer was used to implement a servo-control arrangement wherein environmental feedback to a behaving animal oscillates sinusoidally in real time. The location and period of behavior rhythms generated by the servo-control arrangement covary with the location and period of the sinusoidal command signal.     

Modality effects in the coding reproduction of rhythms

The temporal coding assumption is that time of presentation is coded more accurately for auditory events than for visual events. This assumption has been used to explain the modality effect, in which recall of recent auditory events is superior to recall of recent visual events. We tested the temporal coding assumption by examining the coding and reproduction of quintessentially temporal stimuli-rhythms. The rhythms were produced by sequences of short and long auditory stimuli or short and long visual stimuli; in either case, the task was to reproduce the temporal sequence. The results from four experiments demonstrated reproduction of auditory rhythms superior to that of visual rhythms. We conclude that speech-based explanations of modality effects cannot accommodate these findings, whereas the findings are consistent with explanations based on the temporal coding assumption.     

日周期类型与心理健康

个体间表现出的昼夜节律差异现象可以从日周期类型上进行分类, 包括偏爱早睡早起的清晨型, 偏爱晚睡晚起的夜晚型以及处于两者之间的中间型。已有研究表明, 夜晚型与心境障碍、注意缺陷多动障碍和进食障碍等心理疾病有关, 而日周期类型与心理健康的关系可能受到基因、社会时差、人格等因素的影响。未来应改进研究设计和测量方法, 深入考察日周期类型与心理健康的关系及其作用机制, 以及在我国文化背景下推进日周期类型与心理健康的关系研究。