Effects of sleep deprivation on cortical activation during directed attention in the absence and presence of visual stimuli

Sleep deprivation (SD) can give rise to faltering attention but the mechanics underlying this remain uncertain. Using a covert attention task that required attention to a peripheral target location, we compared the effects of attention and SD on baseline activity prior to visual stimulation as well as on stimulus-evoked activity. Volunteers were studied after a night of normal sleep (RW) and a night of SD. Baseline signal elevations evoked by preparatory attention in the absence of visual stimulation were attenuated within rFEF, rIPS (sparing SEF) and all retinotopically mapped visual areas during SD, indicative of impaired endogenous attention. In response to visual stimuli, attention modulated activation in higher cortical areas and extrastriate cortex (hV4, ventral occipital areas) after RW. SD attenuated rFEF, rIPS, V3a and VO stimulus-evoked activation regardless of whether stimuli were attended. Notably, the modulation of stimulus-evoked activation by attention was not affected by SD unlike for the preparatory period, suggesting a reduced number, but still functional circuits during SD. Deficits in endogenous attention in SD dominate in the preparatory period, whereas changes in stimulus-related activation arise from an interaction between compromised fronto-parietal top-down control of attention and reduced sensitivity of extrastriate visual cortex to top-down or bottom-up inputs.

Sleep deprivation and interference by emotional distracters

STUDY OBJECTIVES

We determined if sleep deprivation would amplify the effect of negative emotional distracters on working memory.

DESIGN

A crossover design involving 2 functional neuroimaging scans conducted at least one week apart. One scan followed a normal night of sleep and the other followed 24 h of sleep deprivation. Scanning order was counterbalanced across subjects.

SETTING

The study took place in a research laboratory.

PARTICIPANTS

24 young, healthy volunteers with no history of any sleep, psychiatric, or neurologic disorders.

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

Study participants were scanned while performing a delayed-response working memory task. Two distracters were presented during the maintenance phase, and these differed in content: highly arousing, negative emotional scenes; low-arousing, neutral scenes; and digitally scrambled versions of the pictures. Irrespective of whether volunteers were sleep deprived, negative emotional (relative to neutral) distracters elicited greater maintenance-related activity in the amygdala, ventrolateral prefrontal cortex, and fusiform gyri, while concurrently depressing activity in cognitive control regions. Individuals who maintained or increased distracter-related amygdala activation after sleep deprivation showed increased working memory disruptions by negative emotional distracters. These individuals also showed reduced functional connectivity between the amygdala and the ventromedial and dorsolateral prefrontal cortices, regions postulated to mediate cognitive control against emotional distraction.

CONCLUSIONS

Increased distraction by emotional stimuli following sleep deprivation is accompanied by increases in amygdala activation and reduced functional connectivity between the amygdala and prefrontal cognitive control regions. These findings shed light on the neural basis for interindividual variation in how negative emotional stimuli might distract sleep deprived persons.

Sleep deprivation impairs object-selective attention: a view from the ventral visual cortex

Background

Most prior studies on selective attention in the setting of total sleep deprivation (SD) have focused on behavior or activation within fronto-parietal cognitive control areas. Here, we evaluated the effects of SD on the top-down biasing of activation of ventral visual cortex and on functional connectivity between cognitive control and other brain regions.

Methodology/Principal Findings

Twenty-three healthy young adult volunteers underwent fMRI after a normal night of sleep (RW) and after sleep deprivation in a counterbalanced manner while performing a selective attention task. During this task, pictures of houses or faces were randomly interleaved among scrambled images. Across different blocks, volunteers responded to house but not face pictures, face but not house pictures, or passively viewed pictures without responding. The appearance of task-relevant pictures was unpredictable in this paradigm. SD resulted in less accurate detection of target pictures without affecting the mean false alarm rate or response time. In addition to a reduction of fronto-parietal activation, attending to houses strongly modulated parahippocampal place area (PPA) activation during RW, but this attention-driven biasing of PPA activation was abolished following SD. Additionally, SD resulted in a significant decrement in functional connectivity between the PPA and two cognitive control areas, the left intraparietal sulcus and the left inferior frontal lobe.

Conclusions/Significance

SD impairs selective attention as evidenced by reduced selectivity in PPA activation. Further, reduction in fronto-parietal and ventral visual task-related activation suggests that it also affects sustained attention. Reductions in functional connectivity may be an important additional imaging parameter to consider in characterizing the effects of sleep deprivation on cognition.

Sleep deprivation and its effects on object-selective attention

Sleep deprivation (SD) affects attention but it is an open question as to whether all subtypes of attention are similarly affected. We investigated the effects of 24 h of total SD on object-selective attention. 26 healthy, young adults viewed quartets of alternating faces or place scenes and performed selective judgments on faces only, scenes only or both faces and scenes. Volunteers underwent fMRI following a normal night of sleep and again following approximately 24 h of total sleep deprivation in a counterbalanced fashion. Sleep deprivation resulted in slower and less accurate picture classification as well as poorer recognition memory for scenes. Attention strongly modulated activation in the Parahippocampal Place Area (PPA). Task-related activation in the fronto-parietal cortex and PPA was reduced in SD, but the relative modulation of PPA activation by attention was preserved. Psychophysiological interaction between the left intra-parietal sulcus and the PPA that was clearly present after a normal night of sleep was reduced below threshold following SD suggesting that PPI may be a more sensitive method of detecting change in selective attention. Sleep deprivation may affect object-selective attention in addition to exerting a task-independent deficit in attention.