title: Beyond Emotional and Spatial Processes: Cognitive Dysfunction in a Depressive Phenotype Produced by Long Photoperiod Exposure.
abstract: Cognitive dysfunction in depression has recently been given more attention and legitimacy as a core symptom of the disorder. However, animal investigations of depression-related cognitive deficits have generally focused on emotional or spatial memory processing. Additionally, the relationship between the cognitive and affective disturbances that are present in depression remains obscure. Interestingly, sleep disruption is one aspect of depression that can be related both to cognition and affect, and may serve as a link between the two. Previous studies have correlated sleep disruption with negative mood and impaired cognition. The present study investigated whether a long photoperiod-induced depressive phenotype showed cognitive deficits, as measured by novel object recognition, and displayed a cognitive vulnerability to an acute period of total sleep deprivation. Adult male Wistar rats were subjected to a long photoperiod (21L:3D) or a normal photoperiod (12L:12D) condition. Our results indicate that our long photoperiod exposed animals showed behaviors in the forced swim test consistent with a depressive phenotype, and showed significant deficits in novel object recognition. Three hours of total sleep deprivation, however, did not significantly change novel object recognition in either group, but the trends suggest that the long photoperiod and normal photoperiod groups had different cognitive responses to total sleep deprivation. Collectively, these results underline the extent of cognitive dysfunction present in depression, and suggest that altered sleep plays a role in generating both the affective and cognitive symptoms of depression.
authors.affiliation: Department of Anesthesiology, Graduate School of Medicine, The University of Tennessee, Knoxville, TN, United States of America.|Department of Psychology, College of Arts and Sciences, The University of Tennessee, Knoxville, TN, United States of America.
authors.forename: Abigail K
authors.initials: AK
authors.lastname: Barnes
authors.affiliation: Department of Psychology, College of Arts and Sciences, The University of Tennessee, Knoxville, TN, United States of America.
authors.forename: Summer B
authors.initials: SB
authors.lastname: Smith
authors.affiliation: Department of Anesthesiology, Graduate School of Medicine, The University of Tennessee, Knoxville, TN, United States of America.|Department of Psychology, College of Arts and Sciences, The University of Tennessee, Knoxville, TN, United States of America.|Program in Comparative and Experimental Medicine, College of Veterinary Medicine, The University of Tennessee, Knoxville, TN, United States of America.
authors.forename: Subimal
authors.identifier: http://orcid.org/0000-0003-1786-238X
authors.initials: S
authors.lastname: Datta
mesh_terms: D000818:Animals; D001007:Anxiety; D001522:Behavior, Animal; D060825:Cognitive Dysfunction; D003863:Depression; D004644:Emotions; D008297:Male; D018782:Maze Learning; D010641:Phenotype; D017440:Photoperiod; D010805:Physical Conditioning, Animal; D051381:Rats; D012892:Sleep Deprivation; D013997:Time Factors