Sleep: suppression of rapid eye movement phase in the cat after electroconvulsive shock

Electroconvulsive shock, administered for 5 to 7 days, reduced the daily rapid eye movement sleep time of seven cats to as little as 28 percent of base line levels. After day 4, eye movements during periods of cortical activation without tonic electromyographic activity were greatlyreduced. Although partially deprived of rapid eye movements for as long as 7 days, the cats showed no compensatory rise in rapid eye movement time during the recovery period, but controls equally deprived gave significant rebounds. Rapid eye movement time of anesthetized cats was not affected by current that usually produces con vulsions; it was lowered in animals convulsed with metrazol, but the same dosage of this drug, administered so as to avoid convulsions, had little eflect.It appears that some aspect of the convulsion is responsible for lowering the rapid eye movement time.     

Sleep: the effect of electroconvulsive shock in cats deprived of REM sleep

Three cats were deprived of rapid-eye-movement (REM) sleep for 10 days, and three were deprived for 12 days. All cats received an electrically induced convulsion on each of the last 3 days of deprivation, as well as on the 1st recovery day just prior to sleep onset. As controls, four cats were deprived of REM sleep for 12 days and one was deprived for 10 days; the controls received no convulsions. Compensatory increases in REM sleep during recovery days were present in the convulsed animals, but were substantially lower than the recovery increases of control animals. During recovery REM sleep, convulsed cats did not display the exaggerated bursts of eye movements and body twitches seen in the nonconvulsed controls.     

Retrograde amnesia: electroconvulsive shock effects after termination of rapid eye movement sleep deprivation

Mice that were deprived of rapid eye movement sleep for 2 days immediately after one-trial training in an inhibitory avoidance task and were given an electroconvulsive shock after deprivation displayed retrograde amnesia on a retention test given 24 hours later. Electroconvulsive shock produced no amnesia in comparable groups of animals that were not deprived of rapid eye movement sleep.     

Sleep: changes in threshold to electroconvulsive shock in rats after deprivation of "paradoxical" phase

Rats were deprived of paradoxical (radid eye movement or REM) sleep for a 6-day period but were allowed substantial non-REM (slow wave) sleep. Thresholds for electroconvulsive shock dropped significantly after deprivation in all these animals, but thresholds in control animals treated in a similar manner, but allowed REM sleep exhibited no change. Deprivation seems to heighten neural excitability.     

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.     

Encephalic cycles during sleep and wakefulness in humans: a 24-hour pattern

Twenty-four-hour polygraphic tracings from normal humans indicate that a pattern of alternating periods of the presence and absence of rapid eye movement, shown to exist for normal sleep, exist over all 24 hours of the daily period. This finding suggests that the so-called sleep-dream cycle of human sleep is not specific to sleep, but is a general activity pattern of the brain.     

Anemia in sleep-deprived rats receiving anticoagulants

Independent groups of rats were deprived of sleep and treated with the anticoagulant drugs phenylindanedione or dicoumarol for 1 to 8 days. These animals developed an extremely severe anemia which was accelerated by p-chlorophenylalanine. The red cell count and amount of hemoglobin decreased to half of normal values. No decrease occurred in animals subjected to any one single treatment. Histological examination indicated hemolysis, hypoplasia of hemopoietic organs, slight hemorrhage, but no evidence of stress. The severity of the anemia was inversely related to the amount of sleep permitted during sleep deprivation. This new syndrome demonstrates marked effects of sleep deprivation on both maturation and destruction of red blood cells. Depletion of serotonin by injection of parachlorophenylalanine blocked the increase in amount of brain waves of the type commonly seen in slow wave sleep but did not eliminate the production of these waves. This result is at variance with the theory that serotonin is the neurochemical responsible for the "priming" of slow wave sleep.     

Sleep stage characteristics of long and short sleepers

The possibility of different sleep stage characteristics being associated with different sleep lengths was explored by comparing two groups of high school seniors, who characteristically slept 6(1/2) hours or less or who slept 8(1/2) hours or more, with an age-matched control group not selected on the basis of sleep length. All-night electroencephalography was used to examine the sleep stage characteristics of these groups. Compared with the unselected age-matched group, the short sleepers showed no significant diminution in their stage 4 (deep) or rapid eye movement (dream) sleep. The long sleepers were observed to obtain significantly more rapid eye movement sleep than did the other groups.     

Odor cues during slow-wave sleep prompt declarative memory consolidation

Sleep facilitates memory consolidation. A widely held model assumes that this is because newly encoded memories undergo covert reactivation during sleep. We cued new memories in humans during sleep by presenting an odor that had been presented as context during prior learning, and so showed that reactivation indeed causes memory consolidation during sleep. Re-exposure to the odor during slow-wave sleep (SWS) improved the retention of hippocampus-dependent declarative memories but not of hippocampus-independent procedural memories. Odor re-exposure was ineffective during rapid eye movement sleep or wakefulness or when the odor had been omitted during prior learning. Concurring with these findings, functional magnetic resonance imaging revealed significant hippocampal activation in response to odor re-exposure during SWS.     

Observational Learning in Octopus vulgaris

Untrained Octopus vulgaris (observers) were allowed to watch conditioned Octopus(demonstrators) perform the task of selecting one of two objects that were presented simultaneously and differed only in color. After being placed in isolation, the observers, in a similar test, consistently selected the same object as did the demonstrators. This learning by observation occurred irrespective of the object chosen by the demonstrators as the positive choice and was more rapid than the learning that occurred during the conditioning of animals. The task was performed correctly without significant errors and further conditioning for 5 days. These results show that observational learning can occur in invertebrates.     

Monocularly deprived cats: improvement of the deprived eye's vision by visual decortication

Monocularly deprived cats were tested for visual perinetry before and after visual cortex lesions. Such a lesion greatly enhances the deprived eye's performance and impairs that of the nondeprived eye so that the pronounced preoperative interocular asymmetry is lost postoperatively. Apparently this destruction of abnormal corticotectal pathways allows the expression of previously suppressed, normal retinotectal pathways.     

Spontaneous middle ear muscle activity in man: a rapid eye movement sleep phenomenon

Changes in compliance of the tympanic membrane have been detected in normal human sleep, presumably due to spontaneous contraction of the stapedius and tensor tympani muscles of the middle ear. In the waking state, these muscles generally respond to loud sound (middle ear reflex). Middle ear muscle activity typically erupts before or at the onset of rapid eye movement (REM) sleep and persists throughout the REM period in a discontinuous pattern resembling that exhibited by rapid eye movements. Approximately 80 percent of all nocturnal middle ear muscle activity is contained in REM sleep. Half of the remaining 20 percent occurs in the 10-minute intervals just prior to the onset of REM sleep. Middle ear muscle activity is often associated with other phasic events such as momentary enhancement of electromyogram inhibition, apnea, and K complexes. Rapid eye movements and middle ear muscle activity, though significantly correlated in REM sleep, are not always simultaneous.     

Rapid extragranular plasticity in the absence of thalamocortical plasticity in the developing primary visual cortex

Monocular deprivation during early postnatal development remodels the circuitry of the primary visual cortex so that most neurons respond poorly to stimuli presented to the deprived eye. This rapid physiological change is ultimately accompanied by a matching anatomical loss of input from the deprived eye. This remodeling is thought to be initiated at the thalamocortical synapse. Ocular dominance plasticity after brief (24 hours) monocular deprivation was analyzed by intrinsic signal optical imaging and by targeted extracellular unit recordings. Deprived-eye responsiveness was lost in the extragranular layers, whereas normal binocularity in layer IV was preserved. This finding supports the hypothesis that thalamocortical organization is guided by earlier changes at higher stages.     

Paradoxical sleep: effect of low partial pressures of atmospheric oxygen

When cats are subjected to an atmosphere of 100 percent oxygen at a sufficiently low pressure, their sleeping patterns are changed: paradoxical sleep disappears and drowsiness increases. This change appears when the pressure decreases to a level close to that at which the hemoglobin begins to dissociate. Return of a cat to a normal atmosphere produces a rebound: the cat spends more time in paradoxical sleep than it did during the base-line period. This finding suggests that a mechanism, closely related to the metabolism of oxygen in the brain, must play an important role in the production of paradoxical sleep. Yet the increase in paradoxical sleep after decompression indicates that still other mechanisms must merge to produce paradoxical sleep.     

Neuronal activity in narcolepsy: identification of cataplexy-related cells in the medial medulla

Narcolepsy is a neurological disorder characterized by sleepiness and episodes of cataplexy. Cataplexy is an abrupt loss of muscle tone, most often triggered by sudden, strong emotions. A subset of cells in the medial medulla of the narcoleptic dog discharged at high rates only in cataplexy and rapid eye movement (REM) sleep. These cells were noncholinergic and were localized to ventromedial and caudal portions of the nucleus magnocellularis. The localization and discharge pattern of these cells indicate that cataplexy results from a triggering in waking of the neurons responsible for the suppression of muscle tone in REM sleep. However, most medullary cells were inactive during cataplexy but were active during REM sleep. These data demonstrate that cataplexy is a distinct behavioral state, differing from other sleep and waking states in its pattern of brainstem neuronal activity.     

Computer-detected patterns of electroencephalographic delta activity during and after extended sleep

Delta (0.5 to 3 hertz) waves are the electroencephalographic hallmark of human sleep. We measured their rate of production during and following an extended night of sleep. On the extended night, we confirmed previous observations of a linear decline in delta wave production across the first four periods of non-rapid-eye-movement (non-REM) sleep. An asymptote was reached in the fifth non-REM period, perhaps signifying that sleep processes reached completion. On the day after the extended night, subjects were allowed to remain awake 3.6 hours less than normal. During the next sleep session, amplitude and number of delta waves in non-REM periods 1 and 3 were significantly reduced. These findings illustrate the value of computer analysis of electroencephalographic waveforms in sleep. Systematic measurement of the amount and distribution of these waveforms as a function of preceding waking duration should provide clues to the kinetics of the metabolic processes underlying sleep.     

Sleep and memory

Two experiments demonstrated that memory over an interval with relatively high amounts of rapid eye movement (REM) sleep was inferior to memory over an interval with relatively high amounts of stage 4 sleep. The results suggest that, at least for humans, REM sleep does not facilitate memory consolidation and that stage 4 sleep may be beneficial to memory.     

Changes of simple and complex spike activity of cerebellar purkinje cells with sleep and waking

Action potentials of cerebellar Purkinje cells were observed in intact monkeys during sleep and waking. Purkinje cells exhibit two sorts of action potentials, called simple and complex spikes, and these two sorts of spikes were differently affected by sleep. Simple-spike activity (generated by the parallel fiber inputs to the Purkinje cell) was highest during sleep with rapid eye movements as compared with both waking and sleep with electroencephalographic slow waves. In contrast, complex-spike activity (generated by the climbing fiber inputs to the Purkinje cell) was lowest during sleep with rapid eye movements. The complex action potential of the Purkinje cell consists of an initial large spike followed by one or more smaller secondary spikes, and the number of these secondary spikes was found to be independent of the background discharge frequency of the simple spike. This independence suggests a possible role of presynaptic factors rather than the excitability level of the Purkinje cell itself in determining the number of secondary discharges occurring in the complex spike.     

Sleep patterns of the monkey and brain serotonin concentration: effect of p-chlorophenylalanine

The amount of time that monkeys (Macaca mulatta) slept was reduced after they were given p-chlorophenylalanine, a selective depletor of serotonin in animal tissues. The time spent in the rapid eye movement stage of sleep was unchanged, but the time in other sleep stages decreased. Seven regions of the brain had a 31 to 46 percent decrease in serotonin content; the concentration of cerebellar serotonin increased by 44 percent.     

Long Evans鼠初级视皮层眼优势柱可塑性的发育性变化

目的:利用电生理学技术探讨Long Evans大鼠视皮层眼优势柱可塑性的发育性变化。方法:取22d Long Evans大鼠7只和100d Long Evans大鼠5只,通过缝合一侧眼睑建立单眼剥夺大鼠动物模型。利用电生理学技术检测22 d正常大鼠、22 d单眼剥夺大鼠、100 d正常大鼠、100 d单眼剥夺大鼠眼优势柱的分布。结果:正常22 d Long Evans大鼠、正常100 d Long Evans大鼠和100 d单眼剥夺大鼠视皮层眼优势柱分布为对侧眼优势,22 d单眼剥夺大鼠视皮层眼优势柱分布为同侧眼优势。结论:正常视觉环境下发育的Long Evans大鼠,其眼优势柱的分布为对侧眼优势,幼年Long Evans大鼠视皮层具有可塑性,异常的视觉环境能影响其眼优势柱的分布;成年Long Evans大鼠视觉可塑性终止,异常的视觉环境不能再影响其眼优势柱的分布。