Biomedical subjects

Jean Foret

Publications and source records attributed to Jean Foret.

5 recordsLinked to original sources

PubMed2006

Slow wave sleep and recollection in recognition memory.

Recognition memory performance reflects two distinct memory processes: a conscious process of recollection, which allows remembering specific details of a previous event, and familiarity, which emerges in the absence of any conscious information about the context in which the event occurred. Slow wave sleep (SWS) and rapid eye movement (REM) sleep are differentially involved in the consolidation of different types of memory. The study assessed the effects of SWS and REM sleep on recollection, by means of the "remember"/"know" paradigm. Subjects studied three blocks of 12 words before a 3-h retention interval filled with SWS, REM sleep or wakefulness, placed between 3 a.m. and 6 a.m. Afterwards, recognition and recollection were tested. Recollection was higher after a retention interval rich in SWS than after a retention interval rich in REM sleep or filled with wakefulness. The results suggest that SWS facilitates the process of recollection in recognition memory.

Adult↗

PubMed2006

Effects of partial sleep deprivation on within-format and cross-format priming.

STUDY OBJECTIVES: The purpose of this study was to examine the effects of sleep on long-term priming. We report the results of a preliminary experiment that enabled us to verify that priming can last for 4 hours, and we also report the results of a study of partial sleep-deprivation. DESIGN: Subjects performed 2 tasks: within-format and cross-format priming. SETTINGS: Sleep laboratory. PARTICIPANTS: Ninety-eight healthy young subjects participated in the 2 studies reported here: 48 in the preliminary experiment and 50 in the sleep-deprivation study. INTERVENTION: Testing after a 4-hour diurnal retention interval (Experiment 1) or after an equivalent interval filled with early or late sleep, or corresponding periods of wakefulness (Experiment 2). MEASUREMENTS AND RESULTS: A tachistoscopic identification paradigm, consisting of naming aloud briefly flashed drawings, was used to assess 2 priming conditions: a same-format or within-format condition (in which items were drawings in the study and test phases) and a different- or cross-format condition (in which the symbolic format of the items differed between the 2 phases: words/drawings). In Experiment 1, we revealed significant priming effects in both conditions after a 4-hour interval. In Experiment 2, only same-format priming effects were observed, but their magnitude was smaller than in Experiment 1. There was no significant difference in priming scores between the sleep and wake groups. CONCLUSIONS: Sleep does not appear to have a strong effect on priming. Instead, priming appears to be affected by circadian influences.

Adolescent↗

PubMed2005

The relationships between memory systems and sleep stages.

Sleep function remains elusive despite our rapidly increasing comprehension of the processes generating and maintaining the different sleep stages. Several lines of evidence support the hypothesis that sleep is involved in the off-line reprocessing of recently-acquired memories. In this review, we summarize the main results obtained in the field of sleep and memory consolidation in both animals and humans, and try to connect sleep stages with the different memory systems. To this end, we have collated data obtained using several methodological approaches, including electrophysiological recordings of neuronal ensembles, post-training modifications of sleep architecture, sleep deprivation and functional neuroimaging studies. Broadly speaking, all the various studies emphasize the fact that the four long-term memory systems (procedural memory, perceptual representation system, semantic and episodic memory, according to Tulving's SPI model; Tulving, 1995) benefit either from non-rapid eye movement (NREM) (not just SWS) or rapid eye movement (REM) sleep, or from both sleep stages. Tulving's classification of memory systems appears more pertinent than the declarative/non-declarative dichotomy when it comes to understanding the role of sleep in memory. Indeed, this model allows us to resolve several contradictions, notably the fact that episodic and semantic memory (the two memory systems encompassed in declarative memory) appear to rely on different sleep stages. Likewise, this model provides an explanation for why the acquisition of various types of skills (perceptual-motor, sensory-perceptual and cognitive skills) and priming effects, subserved by different brain structures but all designated by the generic term of implicit or non-declarative memory, may not benefit from the same sleep stages.

Animals↗

PubMed2004

Consolidation of strictly episodic memories mainly requires rapid eye movement sleep.

STUDY OBJECTIVES: The aim of this study is to examine the effects of sleep deprivation during the first or second half of the night on episodic memory consolidation. Episodic memory is defined as memory for events located in time and space. It is also characterized by autonoetic consciousness, which gives a subject the conscious sensation of traveling back in time to relive the original event and forward into the future. DESIGN: Consolidation of episodic information was tested after 4-hour retention intervals, which followed learning and occurred during either the early or late half night, respectively dominated by slow wave sleep (SWS) or rapid eye movement (REM) sleep, or corresponding periods of wakefulness. SETTING: Data collection occurred in the sleep laboratory. PARTICIPANTS: Forty-three young healthy subjects: 9 men and 34 women, age ranging from 18 to 26 years (mean 20.18 +/- 1.94 years) were included in this study. INTERVENTIONS: Waking after a 4-hour retention interval filled with early or late sleep, or 4-hour sleep deprivation, during early or late period of night. MEASUREMENTS AND RESULTS: The cognitive task, named the What-Where-When test, was specially designed to assess factual, spatial, and temporal components of episodic memory. This task was associated with the Remember/Know paradigm to assess autonoetic consciousness. We measured performance on immediate free recall, delayed free recall (after a 4-hour interval of wakefulness or sleep), and delayed recognition. We also calculated a forgetting rate for each feature (factual, spatial, and temporal) and, for the recognition task, scores of autonoetic consciousness (R responses). REM-sleep deprivation was associated with significantly lower recall of spatial information compared to SWS deprivation (P < .01) or late sleep (P < .05) conditions. REM-sleep deprivation was also associated with a higher forgetting rate of temporal information as compared to the early sleep condition (P< .01). Finally, REM-sleep deprivation led subjects to give significantly fewer R responses, indicative of true memories, as compared to SWS deprivation (P < .05). CONCLUSIONS: These results suggest that consolidation of truly episodic memories mainly involves REM sleep.

Adolescent↗

PubMed2004

Sleep strategies of 12-hour shift nurses with emphasis on night sleep episodes.

OBJECTIVES: Episodes of sleep during a nightshift are frequently reported in various types of jobs. This phenomenon has been seldom documented so far. This field study investigated individual differences in the sleep-wake behavior of nurses. METHODS: A group of eight nurses working in an intensive care unit on a two 12-hour shift system kept a "sleep diary" for 1 month, recording main sleep periods and naps. They subjectively assessed sleepiness, sleep quality, and the need for sleep at various times of the day and night. Continuous actimetric measurements provided an evaluation of the rest-activity patterns and of the sleep parameters. RESULTS: Half of the nurses chose to take naps in 75% of their nightshifts. No differences between the night-nappers and nonnight-nappers were found for either total sleep length or the temporal patterns of subjective sleepiness at night but, during nightwork, night-nappers needed sleep earlier than nonnight-nappers. They had long naps during a worknight and short daytime sleep, sometimes followed by a late afternoon nap. This strategy probably favored the maintenance of a diurnal orientation. Nonnight-nappers had long daytime sleep and took preventive naps to anticipate sleepiness during nightwork. However, their readjustment to diurnal life seemed more difficult than that of night-nappers. CONCLUSIONS: Nurses use different sleep-wake strategies to cope with nightwork. These different strategies may be due to circadian influence although social factors cannot be totally excluded.

France↗