Sleep Homeostasis in Infant Rats.

Homeostatic regulation is a defining characteristic of sleep but has rarely been examined in infants. This study presents an automated method of sleep deprivation in which 5-day-old rats were shocked whenever the nuchal muscle became atonic. The intensity of shock was always set at the minimal level required to maintain arousal. Deprived pups exhibited rapid increases in sleep pressure, as evidenced by increased attempts to enter sleep and subsequent increases in sensory threshold; this increased sensory threshold was not due to sensory adaptation of peripheral receptors. In addition, myoclonic twitching was suppressed during the 30-min deprivation period, leading to rebound twitching during recovery sleep. These results provide the earliest demonstration of the homeostatic regulation of sleep in an altricial mammal. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sniffing in Infant Rats During Sleep and Wakefulness.

Sniffing, a behavior that enhances detection and localization of odorants, is typically assumed to require behavioral arousal. In an effort to determine whether sniffing and arousal are dissociable, dimethyl disulfide (DMDS) was presented to 8-day-old rats while respiration and behavioral state were monitored. Pups sniffed in response to the highest concentrations of DMDS, exhibiting a lower olfactory threshold when awake. Surprisingly, sniffing occurred even while pups remained asleep. Sniffing was mediated by the olfactory system, as evidenced by the abolition of sniffing when the lateral olfactory tracts, were cut and the retention of rapid arousal in response to a trigeminal stimulant, acetic acid. Finally, sleeping pups presented with acetic acid awakened without sniffing. Thus, although olfactory threshold increases during sleep, sleeping does not preclude sniffing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sleep, wakefulness, and consciousness.

This paper presents an analysis of some of the major issues concerning the evolutionary theory of sleep and wakefulness proposed by the writer some 2 decades ago. A discussion of the current controversy over the research literature in this area is included. 16 references. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Separable Brainstem and Forebrain Contributions to Ultrasonic Vocalizations in Infant Rats.

Competing views persist concerning the functional significance of ultrasonic vocalizations (USVs) emitted by infant rats. One perspective holds that USVs result from an emotional state of fear and anxiety, the adult expression of which depends in part on forebrain mechanisms. Here the authors examine whether pups lacking forebrain input are capable of emitting USVs. Aspirations of neocortex and hippocampus or precollicular decerebrations were performed on 8-day-old rats. After the rats recovered, USV responses were recorded for 10 min at room temperature (Phase 1) followed by enhanced cooling for 20 min (Phase 2). Experimental pups emitted significantly fewer USVs than shams during Phase 1 but vocalized at similar rates during Phase 2. Thus, in infants, brainstem neural circuitry is sufficient to support emission of USVs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Positive Geotaxis in Infant Rats (Rattus norvegicus) : A Natural Behavior and a Historical Correction.

Infant rats (Rattus norvegicus) placed on a shallow incline (2°, 4°, or 8°) oriented and moved downhill within 1 min; that is, they displayed positive geotaxis. Their downhill translocation increased with angle of inclination. A variety of possible behavioral elements (e.g., initial orientation, rotational movements, ambulatory velocities) were eliminated as explanations of the geotaxis. Wall contact was recognized as a determinative event: Pups on the inclines showed no orientation with respect to the geogravitational stimulus before contacting a wall. The event of wall contact, however, evoked reliable downhill orientation and more linear movements. Positive geotaxis was created by pups' orientation against walls and an associated increase in movement velocity. This is a distinct perspective on a behavioral response that replaces a traditionally misinterpreted phenomenon. The authors discuss the ecological validity and historical context of these findings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Infant sleep and parental sleep-related cognitions.

Infant sleep is a major source of distress in many families. The purpose of this study was to assess infant sleep and parental sleep-related cognitions about infant sleep in clinical and control samples. The clinical sample consisted of 48 infants referred to a sleep clinic because of night-wakings problems. The control sample included 48 infants with no parental complaints about sleep difficulties. Sleep of all participating infants was monitored for 1 week with actigraphs and parental daily logs. Parents completed 2 questionnaires testing their cognitions about infant sleep. As expected, significant group differences were found with regard to the sleep-quality measures and parental cognitions. Parental cognitions about difficulties in limit setting were associated with poorer sleep quality. Significant differences were found between fathers and mothers on the cognitions scales. The results highlight the links between parental cognitions and infant sleep and the unique perspective of each parent in this area. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sleep deprivation in adolescents and adults: Changes in affect.

The present study investigated the impact of sleep deprivation on several aspects of affective functioning in healthy participants selected from three different developmental periods: early adolescence (ages 10–13), midadolescence (ages 13–16), and adulthood (ages 30–60). Participants completed an affective functioning battery under conditions of sleep deprivation (a maximum of 6.5 hours total sleep time on the first night followed by a maximum of 2 hours total sleep time on the second night) and rest (approximately 7–8 hours total sleep time each night for two consecutive nights). Less positive affect was observed in the sleep-deprived, compared to rested, condition. This effect held for 9 of the 12 positive affect items on the PANAS-C. Participants also reported a greater increase in anxiety during a catastrophizing task and rated the likelihood of potential catastrophes as higher when sleep deprived, relative to when rested. Early adolescents appraised their main worry as more threatening when sleep deprived, relative to when rested. These results support and extend previous research underscoring the adverse affective consequences of sleep deprivation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

酒钢2号高炉热风炉热平衡及热效率的计算与分析

本文通过对酒钢2号高炉3座热风炉的热平衡进行测定,并根据测定结果计算3座热风炉的热效率。通过对热平衡及热效率的分析,指出热风炉现存在的问题,并提出如何解决存在的问题,提高热风炉风温水平的方法。     

Brainstem and hypothalamic regulation of sleep pressure and rebound in newborn rats.

Sleep pressure and rebound comprise the two compensatory or “homeostatic” responses to sleep deprivation. Although sleep pressure is expressed by infant rats as early as postnatal day (P)5, sleep rebound does not appear to emerge until after P11. We reexamined the developmental expression of these sleep-regulatory processes in P2 and P8 rats by depriving them of sleep for 30 min using a cold, arousing stimulus delivered to a cold-sensitive region of the snout. This method effectively increased sleep pressure over the 30-min period (i.e., increases in the number of arousing stimuli presented over time). Moreover, sleep rebound (i.e., increased sleep during the recovery period) is demonstrated for the first time at these ages. Next, we showed that precollicular transections in P2 rats prevent sleep rebound without affecting sleep pressure, suggesting that the brainstem is sufficient to support sleep pressure, but sleep rebound depends on neural mechanisms that lie rostral to the transection. Finally, again in P2 rats, we used c-fos immunohistochemistry to examine neural activation throughout the neuraxis during sleep deprivation and recovery. Sleep deprivation and rebound were accompanied by significant increases in neural activation in both brainstem and hypothalamic nuclei, including the ventrolateral preoptic area and median preoptic nucleus. This early developmental expression of sleep pressure and rebound and the apparent involvement of brainstem and hypothalamic structures in their expression further solidify the notion that sleep–wake processes in newborns—defined at these ages without reference to state-dependent EEG activity—provide the foundation on which the more familiar processes of adults are built. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The sleep-like nature of early mammalian behavioral rhythms: Theoretical comment on Todd et al. (2010).

Early sleep patterns lack several of the major defining physiological criteria used to identify sleep states in adult animals, but many typical aspects of mature sleep can nevertheless be demonstrated at surprisingly early stages of development. In Todd, Gibson, Shaw, & Blumberg (2010), the ability to compensate for enforced sleep deprivation is found to be present already shortly after birth in laboratory rats, an altricial mammalian species. Whereas the brainstem is capable of resisting enforced wakefulness by an increasing “pressure” to fall asleep, “catch-up” replacement of the lost sleep by means of longer subsequent sleep durations requires forebrain participation. This investigation represents an initial foray into the theoretically important area of the ontogeny of homeostatic regulatory mechanisms for behaviorally crucial neurophysiological processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Noradrenergic System Interacts With Genital Reflexes Induced by Cocaine in Paradoxical Sleep-Deprived Male Rats.

Different doses of α-1, α-2, β-1, and β-2 adrenoceptor agonists or antagonists were administered to paradoxical sleep-deprived (PSD) rats prior to cocaine administration. Methoxamine reduced the percentage of rats displaying erection, whereas prazosin did not. Yohimbine significantly decreased this percentage. For β-1 adrenoceptor drugs, both compounds reduced the percentage of rats displaying erection at the highest dose; β-2 adrenoceptor drugs had no effect. Except for clonidine, all drugs significantly reduced the frequency of erection. Ejaculation was significantly decreased following yohimbine and β-1 drugs, whereas it was completely abolished by prazosin. The results showed that noradrenergic drugs inhibited genital reflexes in PSD rats, with distinct responses in relation to their respective action over the adrenoceptor. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Behavioral characterization of amygdala involvement in mediating intra-accumbens opioid-driven feeding behavior.

The present experiments were conducted to provide a more detailed behavioral analysis of the dissociable roles of the basolateral (BLA) and central nucleus (CeA) of the amygdala in mediating intra-accumbens (Acb) opioid-induced feeding of a high-fat diet. Confirming previous findings, temporary inactivation of the CeA with the GABAA agonist muscimol reduced DAMGO (D-Ala2-NMe-Phe4-Glyol5-enkephalin)-induced and baseline food intake, whereas intra-BLA muscimol selectively blocked only DAMGO-induced food intake, leaving baseline feeding intact. However, although inactivation of the BLA reduced DAMGO-induced food intake to control levels, this treatment led to exaggerated number and duration of food hopper entries after food intake had ended. A subsequent experiment under conditions of limited access to the diet found the identical pattern of behavior following intra-Acb administration of DAMGO, regardless of whether the BLA was inactivated. Last, BLA inactivation was shown to have no influence on feeding driven by a state of negative-energy balance (24-hr food deprivation), demonstrating a specific influence of the BLA on opioid-driven feeding. These findings suggest that BLA mediates palatability-driven feeding and that this influence is particular to the consummatory act of ingestion. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The union of the state: Myoclonic twitching is coupled with nuchal muscle atonia in infant rats.

Active sleep (AS), as measured by the occurrence of myoclonic twitching (MT), is the most prevalent behavioral state in newborn rats. Historically, AS has been considered a developmental precursor of REM sleep, but recently this idea has been questioned. In the present study, the authors assess, in 2-, 5-, and 8-day-old rats, the relationship between MT and nuchal muscle atonia, a widely recognized component of REM sleep. At all ages, muscle atonia preceded MT and persisted until awake behaviors occurred. In addition, muscle tone decreased gradually during transitions from awake behavior to twitching. Thus, MT during infancy occurs against a backdrop of muscle atonia, a result that is consistent with the view that AS is a developmental precursor of REM sleep. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sleep Responses to Light and Dark Are Shaped by Early Experience.

Light regulates sleep timing through circadian entrapment and by eliciting acute changes in behavior. These behaviors are mediated by the subcortical visual system, retinorecipient nuclei distinct from the geniculocortical system. To test the hypothesis that early visual experience shapes light regulation of behavior, the authors recorded sleep in albino rats reared in continuous dark, continuous light, or a 12-hr light-dark cycle. Dark rearing strengthened and light rearing weakened acute responses to light, including light modulation of REM sleep, a marker for pretectal function in albino rats. However, neither dark nor light rearing altered daily amounts of wakefulness, non-REM sleep, or REM sleep. Thus, light and dark rearing might differentially affect the balance between acute and circadian responses to light that, in concert, govern sleep timing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Brief Maternal Interaction Increases Number, Amplitude, and Bout Size of Isolation-Induced Ultrasonic Vocalizations in Infant Rats (Rattus norvegicus).

The number, amplitude, duration, and bout structure of isolation-induced ultrasonic vocalization (USV) of infant rats (Rattus norvegicus) were measured on postnatal Day 10. Measurements were made before and after a brief, 1-min, active interaction with their mother or before and after a "pick-up" control procedure. Consistent with prior studies, the number of USVs emitted was significantly increased in the period following the maternal reunion but not after the control procedure. The average amplitude of USVs was also greater following maternal reunion. Finally, analyses characterizing the bout structure of USV production indicated that the average bout size (i.e.. number of USVs/bout) was increased severalfold following the reunion with the mother, accounting for the greater rate of USV production during the second isolation period. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

蓄热式燃烧技术在环形炉上的应用

简述了自身蓄热式高温空气燃烧技术的原理及特点,介绍了自身蓄热式高温空气燃烧技术在170机组Ф21m环形炉上的改造应用情况,证明自身蓄热式燃烧技术在环形炉上具有推广应用价值.     

Behavioral Limits of Auditory Temporal Resolution in the Rat: Amplitude Modulation and Duration Discrimination.

Thresholds for detecting the presence of amplitude modulation in a noise carrier were determined for rats using conditioned avoidance procedures. There was a progressive increase in threshold with modulation rates between 5 Hz and 2 kHz. Further tests were conducted to determine difference thresholds for detecting an increase in modulation rate for standard rates of 10, 50, and 100 Hz. The size of the difference threshold increased progressively as the standard rate increased. In addition, thresholds for detecting an increase in the duration of a noise burst were determined for various standard durations. The difference thresholds were constant for values between 10 and 50 ms but increased progressively, with standard durations between 0.1 and 1.0 s. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of oral deprivation on responses to subliminal and supraliminal verbal food stimuli.

The effect of 2 kinds of oral deprivation on reactions to a subliminal and supraliminal food stimulus was investigated. Varying hours of food deprivation (1-5 or more) constituted the 1st independent variable; smoking frequency constituted the 2nd. Different groups of Ss were exposed to a word list preceded by: (a) no stimulus, (b) the subliminal stimulus CHEESE, and (c) the supraliminal stimulus CHEESE. The stimulus word was associatively linked to 10 of the words on the recall list. Relative recall of stimulus-related associates was a function of hours of deprivation in the subliminal and supraliminal conditions, and a function of smoking frequency in the subliminal condition. Other nutritional and oral variables were also investigated. (21 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Partner's Stress Status Influences Social Buffering Effects in Rats.

The relationship between a social partner's stress status and the social buffering effect was examined in adult male Wistar rats. Fear-conditioned rats were exposed to the same context along with either a shocked or nonshocked conspecific partner. Changes in body temperature and behavioral responses were monitored in order to compare the effects of social buffering, and the Fos protein in the paraventricular nucleus was immunostained. The presence of the partner rat attenuated stress-induced hyperthermia, as well as behavioral responses and Fos expression in response to the fearful context, and nonshocked partners were more effective than shocked partners. These findings suggest that the social buffering effect depends on the stress status of the accompanying conspecific animal. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Doubling the rate of signal presentation in a vigilance task during sleep deprivation.

An experiment was conducted to test the effect of doubling the amount of work required of Ss after loss of sleep. Ss were required to detect defined sequences of 3 digits ("signals") within an apparently random series. Digits were presented continuously for 30 min. either at 1 per sec. (slow) or 2 per sec. (fast). The slow condition contained 20 signals; the fast condition 40. Slow and fast groups were tested on 3 successive days of a 60-hr. vigil and 2 similar groups under control conditions. The results showed that loss of sleep affects performance under fast less than under slow. These and other results suggested that stimulation reduces the effect of sleepiness on performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)