Sleep clearly influences learning and memory since sleep deprivation and stress impairs both cognitive processes. Working memory is an essential cognitive process and refers to a short-term holding of incoming informa...Sleep clearly influences learning and memory since sleep deprivation and stress impairs both cognitive processes. Working memory is an essential cognitive process and refers to a short-term holding of incoming information required to update the long-term mnemonic storage and to manipulate new elements in order to solve problems and make decisions. Nevertheless, the influence of sleep deprivation on working memory has scarcely been studied. In this study we evaluated working memory using the N-back test after increasing periods of wakefulness. Healthy young males were kept awake for 36 hours and the two N-back tasks with low (1-Back) and high (3-Back) levels of complexity were applied every 6 hours. Additionally, salivary cortisol was determined along the study. Unlike the control non-deprived participants, the sleep deprived volunteers showed a significant decrease in their efficiency to solve the 1-Back task after 24 hours of sleep deprivation. However, no differences were observed after 30 and 36 hours of sleep deprivation. Concerning the 3-Back task no differences were observed after sleep deprivation. Regarding reaction time, the deprived group manifested slower responses for the 1-Back task and for the 3-Back task after 30 hours and 36 hours of sleep deprivation, respectively. Cortisol levels presented the normal daily oscillation and no differences were observed between groups. This data suggests that sleep deprivation affects basal states of attention instead of working memory while performing simple tasks. The impact of sleep deprivation on the cognitive performance depends on the moment of day when the task is applied and the complexity of the tests used to assess these mnemonic skills.展开更多
文摘Sleep clearly influences learning and memory since sleep deprivation and stress impairs both cognitive processes. Working memory is an essential cognitive process and refers to a short-term holding of incoming information required to update the long-term mnemonic storage and to manipulate new elements in order to solve problems and make decisions. Nevertheless, the influence of sleep deprivation on working memory has scarcely been studied. In this study we evaluated working memory using the N-back test after increasing periods of wakefulness. Healthy young males were kept awake for 36 hours and the two N-back tasks with low (1-Back) and high (3-Back) levels of complexity were applied every 6 hours. Additionally, salivary cortisol was determined along the study. Unlike the control non-deprived participants, the sleep deprived volunteers showed a significant decrease in their efficiency to solve the 1-Back task after 24 hours of sleep deprivation. However, no differences were observed after 30 and 36 hours of sleep deprivation. Concerning the 3-Back task no differences were observed after sleep deprivation. Regarding reaction time, the deprived group manifested slower responses for the 1-Back task and for the 3-Back task after 30 hours and 36 hours of sleep deprivation, respectively. Cortisol levels presented the normal daily oscillation and no differences were observed between groups. This data suggests that sleep deprivation affects basal states of attention instead of working memory while performing simple tasks. The impact of sleep deprivation on the cognitive performance depends on the moment of day when the task is applied and the complexity of the tests used to assess these mnemonic skills.
文摘目的探讨功能性近红外光谱成像(functional near-infrared spectroscopy,fNIRS)对重性抑郁障碍(Major Depressive Disorder,MDD)患者的N-back表现及相关脑区激活情况。方法去符合美国《精神障碍诊断与统计手册第5版》(diagnostic and statistical manual of mental disorders,5th Edition,DSM-5)诊断标准的抑郁障碍患者26例为研究对象,并选择22名正常成人作为对照。使用17项汉密尔顿抑郁量表(17-item Hamilton depression scale,HAMD-17)评定患者抑郁症状,数字N-back测试评估工作记忆,应用fNIRS测量执行N-back任务时额叶脑区的激活情况。结果①在正确率和反应时间上,负荷水平主效应显著(P<0.05),组别和负荷水平的交互作用显著(P<0.05)。进行简单效应分析发现,在0-back条件下,MDD患者的正确率和反应时间与健康成人不存在显著差异(P>0.05),在1-back和2-back条件下,MDD患者的正确率和反应时间存在显著性差异(P<0.05)。②与健康对照组相比,MDD患者在2-back任务中,背外侧前额叶皮层(通道3、4、5、6、8)和额极皮层(通道47)氧合血红蛋白(Oxyhemoglobin,Oxy-Hb)的激活明显减少(P<0.05)。结论MDD患者fNIRS实验测试所见证据是背外侧前额叶皮层和额极皮层激活减弱。这一初步结果有待于进一步证实。
