Sleepiness and REM sleep recurrence: the effects of stage 2 and REM sleep awakenings.

Determinants of daytime sleepiness include sleep length, sleep continuity, and circadian factors. Sleep stage composition has not been seen as influencing subsequent daytime functioning; however, earlier studies did not focus explicitly on sleepiness. The present experiment studied the effects of selective sleep-stage restriction on an objective measure of sleep tendency, and explored the relationship between sleepiness and subsequent REM recurrence during REM deprivation. Daytime sleep latency was measured by a modified Multiple Sleep Latency Test prior to and following two nights of awakenings from either REM or Stage 2 sleep in 16 normal young adults. Sleep latency following these awakenings was also measured. REM sleep and Stage 2 awakenings produced comparable levels of sleepiness, both during the Awakening Nights and subsequent daytime Multiple Sleep Latency Testing. Pooling the groups, daytime and nocturnal sleepiness measures were correlated within individuals. In the REM-Awakening Group, Pre-Awakening daytime sleepiness was associated with the tendency for REM sleep to recur following experimental awakenings. Comparable levels of sleepiness may result from nonspecific processes such as sleep curtailment and fragmentation, or alternatively from separate REM and Stage 2 mechanisms. The relationship between REM sleep and sleepiness is discussed in the context of both state and trait models.

The development of scales to measure the experience of self-participation in sleep.

Recent literature suggests that how the self is represented is a cardinal aspect of the dream experience. A review of studies of phasic-tonic distinctions within rapid eye movement (REM) sleep revealed that increasing self-participation marked awakenings from phasic intervals. Five scales specifically designed to measure absorption in dreaming were compared with three scales previously shown to discriminate phasic from tonic awakenings within REM sleep. Eight reports per night (two stage REM, six stage 2) were collected from each of 20 subjects on 4 baseline nights. Awakenings were controlled for time into the REMP and time of night, correcting the methodological flaws of previous studies in this area. Scales developed to measure self-participation were able to discriminate phasic from tonic awakenings better than those already in the literature. Results are discussed in terms of the psychometric properties of the individual scales.

Dynamics of REM sleep in narcolepsy.

The discovery of sleep onset REM periods (SOREMPs) in narcolepsy first suggested the important role of REM sleep in the disorder. We have conducted a series of studies exploring factors that affect the onset and termination of REM sleep in narcolepsy. Following a preliminary study of REM sleep deprivation, we compared the sleep onset response of narcoleptic and normal subjects to awakenings at REM sleep onsets and awakenings during NREM sleep. In addition, we have investigated the relationship of these awakenings to daytime sleepiness. We have demonstrated that an index of the REM sleep process predicts the sleepiness of both normal and narcoleptic subjects. The finding of increased frequency of SOREMPs following both REM and NREM sleep awakenings in the narcoleptic patient suggests that accelerated triggering and inertia of the REM sleep process are pathophysiological mechanisms of the disorder.

Intracranial self-stimulation: temporal interactions among mesencephalic and diencephalic sites.

The monophasic pulse pair technique has been employed to ascertain whether pairs of intracranial self-stimulation (ICSS) sites interact with each other. The present study investigated the interactive properties of ICSS placements in the substantia nigra (SN) and mid-ventral periaqueductal gray (MV) with those hypothalamic ICSS placements within (MFB) or outside of (non MFB) the medial forebrain bundle. ICSS response rates when pulses of each pulse pair were split between two ICSS sites were significantly higher than the sum of rates when each site was stimulated singly with single-pulse trains. Moreover, all interaction conditions yielded higher rates than pulse pairs delivered to the mesencephalic site at an optimal interval, yet similar rates to pulse pair stimulation delivered to the diencephalic site. The symmetry of the interactions depended upon electrode loci: MV/MFB and SN/non MFB interactions were significantly higher when the mesencephalic site received the first pulse of each pair, effects which accounted for 49 and 58% of the variance respectively. Conversely, MV/non MFB and SN/MFB interactions were significantly higher when the mesencephalic site received the second pulse of each pair, effects which accounted for 5 and 14% of the variance respectively. These behavioral ICSS interactions are discussed in terms of interrelated heterogeneous subsystems subserving ICSS behavior.

Brain site variations in effects of morphine on electrical self-stimulation.

Pairs of bipolar electrodes were stereotaxically aimed at two of three sites: the locus coeruleus (LC), the substantia nigra, pars compacta (SNC), and the median forebrain bundle (MFB). Rats were shaped to bar-press for trains of intracranial electrical stimulation presented as pairs of monophasic pulses. The first pulse of a pair (the C, conditioning pulse) was followed by a second pulse (the T, test pulse) after a parametrically varied interval. The effects of chronic morphine administration were tested in a paradigm of 7 days saline, 7 days morphine, 1 day morphine+naloxone, and 6 days post-drug saline. High doses of morphine (5 mg/kg) depressed response rates for intracranial self-stimulation (ICSS). LC placements and those just lateral or ventral to the LC showed large increases in ICSS rates under morphine (2.5 mg/kg). This area was delimited on either side by tips that showed response rate depressions under morphine. MFB placements yielded response rate facilitations under morphine. Sites medial to the MFB and ventral within the MFB showed rate depressions under morphine. Dorsal substantia nigra placements showed facilitated rates, whereas placements ventral within the SNC and substantia nigra, pars reticulata (SNR) produced more variable results, with rates tending to be depressed by morphine. The ICSS procedure may be a useful animal model for detecting the abuse potential of drugs.

An examination of some recent criticisms of psychoanalytic "metapsychology".

Some of the recent criticisms of psychoanalytic metapsychology are discussed, particularly the contributions of Schafer and Rubinstein. An examination of the logic underlying these criticisms indicates that many of them are either I) extratheoretical and say nothing about the scientific status of the theory or formulation under scrutiny; 2) rely on certain a priori philosophical assumptions which, if adopted, would severely limit the scope of psychoanalytic theorizing. Several suggestions are offered which would allow for more fruitful discussion of substantive logical and empirical question.

Morphine and intracranial self-stimulation in the hypothalamus and dorsal brainstem: differential effects of dose, time and site.

The purpose of this study was to examine if morphine, a drug of abuse, exerts site-specific effects on intracranial self-stimulation (ICSS). Rats, implanted with dorsal brainstem (DB) and hypothalamic (HYP) electrodes, bar-pressed for ICSS at two current intensities eight hours a day during six days each of predrug saline, morphine (2.5, 5.0, 7.5 or 10.0 mg/kg) and postdrug saline conditions. There were three patterns of drug effects: "pure" depressions, "pure" facilitations and a biphasic pattern (depressions followed by facilitations). Repeated morphine administration modified the temporal patterning of these effects: shortened duration of depressions and produced earlier onsets of facilitations. Within an animal, DB electrodes displayed more depressions than the HYP electrodes. Tolerance to the depressant effects, observed frequently, occurred occasionally to the facilitative effects of morphine. The drug effects on ICSS were dissociated from those observed on other behavioral measures, and thus are not artifacts of concomitant changes in activity levels.

Characterization of self-stimulation elicited from rat dorsolateral pariaqueductal gray.

Rats were stereotaxically implanted with chronic bipolar electrodes aimed at the periaqueductal central gray (PCG) and were subsequently tested for intracranial self-stimulation (ICSS) behavior. Consistent and reliable ICSS behavior was elicited from both the midventral and dorsolateral portions of the PCG, the latter result occurring in loci previously reported as predominantly aversive. Midventral PCG ICSS rates were significantly higher than dorsolateral PCG ICSS rates. The higher rates were not accounted for by either current intensity used or motor artifacts. Moreover, both sites displayed reliable ICSS behavior characterized by regular low-variability rates and no seizure activity, seen with other brainstem ICSS sites, but unlike diencephalic and telencephalic ICSS behavior which is characterized by irregular bursts of responding which are highly variable and sometimes accompanied by seizures. The differential ICSS responsivity between PCG structures suggests that they may be mediated by different anatomically-localizable substrates.

Alteration of escape from rewarding electrical brain stimulation by D-amphetamine.

Rats were trained both to barpress for and escape from locus coeruleus, midbrain periaqueductal gray and hypothalamic stimulation. Rate-intensity functions for intracranial self-stimulation (ICSS) behavior and latency-intensity functions for escape behavior were obtained for each electrode site in each animal. Following baseline, d-amphetamine was administered and responding was compared with the saline condition for both rate-intensity and latency-intensity functions. ICSS response rates were enhanced by d-amphetamine at all loci, particularly at threshold intensities, while escape responding was biphasically affected by d-amphetamine at all loci. D-amphetamine increased escape latencies at intensities which, under saline, elicited short escape latencies, while decreasing escape latencies at intensities which, under saline, elicited long escape latencies. A significant correspondence was noted between intensities which, under the influence of d-amphetamine, both elicited longer escape latencies and higher ICSS response rates, suggesting that in both ICSS and escape paradigms, animals were titrating the duration of the stimulus train. No site-specific effects of d-amphetamine upon escape behavior were noted.

Comparison of behaviors elicited by electrical brain stimulation in dorsal brain stem and hypothalamus of rats.

Four brain-stimulation phenomena elicited from both dorsal brain stem and hypothalamic sites were investigated with the following results: (a) intracranial self-stimulation rate-intensity functions for dorsal brain stem and hypothalamic sites yielded very high (over 1,000 responses/15 min.) to moderate (201-500 responses/15 min.) response rates; (b) d-amphetamine produced higher response rates than either l-amphetamine or saline at both dorsal brain stem and hypothalamic sites, indicating that noradrenergic dorsal brain stem fibers (or cell bodies) support intracranial self-stimulation; (c) dorsal brain stem and hypothalamic self-stimulation sites reliably produced escape behavior; (d) simultaneous stimulation of dorsal brain stem and hypothalamic sites at subthreshold intensities interacted to produce suprathreshold response rates.

Relation between REM sleep and intracranial self-stimulation.

Depriving rats of rapid eye movement (REM) sleep was shown to lower their thresholds and raise their response rates for rewarding brain stimulation. Conversely, allowing rats to self-stimulate while they were being deprived of this sleep form reduced the amount of REM rebound during recovery from deprivation. These results demonstrate a reciprocal relation between rewarding brain stimulation and REM sleep.

Deafferentation in monkeys: effect on conditioned grasp response.

A preliminary technique was developed for conditioning grasp response in monkeys, for use in studying the effect of damage to the central nervous system on skilled movement. That subjects were able to learn this response with a deafferented hand, in the absence of vision, indicated that purposive movements of the distal musculature are less under the control of peripheral feedback than had been generally believed.