Sleep deprivation in rats produces attentional impairments on a 5-choice serial reaction time task

Abstract

Study objectives: To develop a rodent model of the attentional dysfunction caused by sleep loss.

Design: The attentional performance of rats was assessed after 4, 7, and 10 hours of total sleep deprivation on a 5-choice serial reaction time task, in which rats detect and respond to brief visual stimuli.

Setting: The rats were housed, sleep deprived, and behaviorally tested in a controlled laboratory setting.

Participants: Ten male Long-Evans rats were used in the study.

Interventions: Rats were trained to criteria and subsequently tested in daily sessions of 100 trials at approximately 4:00 PM (lights on 8:00 AM-8:00 PM). Attentional performance was measured after 4, 7, 10 hours of total sleep deprivation induced by gentle handling.

Results: Sleep deprivation produced a monotonic increase in response latencies across the 4-hour, 7-hour, and 10-hour deprivations. Sleep deprivation also led to increased omission errors, but the overall number of perseverative and premature responses was unchanged. Subgroups of rats were differentially affected in the number of omission errors and perseverative responses.

Conclusions: The effects of sleep deprivation on rats are compatible with a range of human findings on the effects of sleepiness on selective attention, psychomotor vigilance, and behavioral control. Rats also exhibited differential susceptibility to the effects of sleep deprivation, consistent with 'trait-like' susceptibility that has been found in humans. These findings indicate the feasibility of using the 5-choice serial reaction time task as an animal model for investigating the direct links between homeostatic sleep mechanisms and resulting attentional impairments within a single animal subject.

Figure 1

The 5-choice reaction time test operant chamber. The behavioral chamber contained 5 evenly spaced ports containing a light stimulus and a sensor that registered nose entry by the interruption of an infrared beam. In each trial, a 0.5-second light stimulus was presented in 1 of 5 ports. A nose poke into the illuminated port triggered the delivery of a sucrose pellet into a reward tray in the opposite wall of the chamber that was accessible through a flap door.

Figure 2

Contingency diagram of the 5-choice reaction time test. Each daily session began with the delivery of 1 free sugar pellet into the reward tray (bottom left) and continued for 100 experimental trials. The release of the flap door, following either a reward or an error, triggered the next stimulus after a 5-seconds intertrial interval (ITI). A timely response into a briefly illuminated port was rewarded with a sucrose pellet (a correct response), and an incorrect response turned off the house lights for 5 seconds (a time out). Incorrect responses include responding before the presentation of a stimulus (a premature response), not responding to the stimulus within 3-second period (an omission error), responding into a port that was not illuminated (incorrect response), and responding repeatedly into a port (a perseverative error, not shown). Credit: Campden Instruments.

Figure 3

Mean latency + SEM of correct responses across the 3 durations of sleep deprivation (4 hours, 7 hours, and 10 hours). Average latency of all matched nondeprivation conditions is shown for comparison (0 hours). Sleep deprivation led to a significant increase in the mean latency of responses following sleep deprivation and a significant interaction of deprivation condition and testing day (deprivation length). Posthoc comparisons of show that 10 hours of sleep deprivation led to significantly increased latency compared with 4 hours of sleep deprivation (*P < .05).

Figure 4

Mean number of correct responses in deprivation and control conditions (+ SEM). The number of correct responses was significantly lower following sleep deprivation (*P < .01). B—Mean number of omission errors in deprivation and control conditions. The number of omission errors was significantly higher following sleep deprivation. (**P < .01).

Figure 5

Effects of sleep deprivation on performance of individual rats. Each point represents the average number of omission errors across control or deprivation conditions for each rat. A significant interaction of rats by deprivation indicates that the performance lapses of individual rats were differentially affected by sleep deprivation. In most rats, sleep deprivation led to an increase in the number of omission errors. However, some rats committed fewer omission errors following sleep deprivation.

Figure 6

Comparison of the number of omission errors of individual rats during the first 10-hour deprivation (Dep 1) versus the second 10-hour deprivation (Dep 2). The rats are rank ordered on the basis of average performance across the 2 sessions. An interclass correlation of the rat’s scores between the 2 weeks was nearly significant (r = 0.703, p = 0.051), indicating a consistency of deprivation effects on the number of omission errors committed by individual rats.