Aberrant Neuronal Dynamics during Working Memory Operations in the Aging HIV-Infected Brain.
Impairments in working memory are among the most prevalent features of HIV-associated neurocognitive disorders (HAND), yet their origins are unknown, with some studies arguing that encoding operations are disturbed and others supporting deficits in memory maintenance. The current investigation directly addresses this issue by using a dynamic mapping approach to identify when and where processing in working memory circuits degrades. HIV-infected older adults and a demographically-matched group of uninfected controls performed a verbal working memory task during magnetoencephalography (MEG). Significant oscillatory neural responses were imaged using a beamforming approach to illuminate the spatiotemporal dynamics of neuronal activity. HIV-infected patients were significantly less accurate on the working memory task and their neuronal dynamics indicated that encoding operations were preserved, while memory maintenance processes were abnormal. Specifically, no group differences were detected during the encoding period, yet dysfunction in occipital, fronto-temporal, hippocampal, and cerebellar cortices emerged during memory maintenance. In addition, task performance in the controls covaried with occipital alpha synchronization and activity in right prefrontal cortices. In conclusion, working memory impairments are common and significantly impact the daily functioning and independence of HIV-infected patients. These impairments likely reflect deficits in the maintenance of memory representations, not failures to adequately encode stimuli.
Department of Neurological Sciences, University of Nebraska Medical Center (UNMC), Omaha, NE, USA.|Department of Pharmacology and Experimental Neuroscience, UNMC,Omaha, NE, USA.|Center for Magnetoencephalography, UNMC, Omaha, NE, USA.
Tony W
TW
Wilson
Center for Magnetoencephalography, UNMC, Omaha, NE, USA.|Department of Psychology, University of Nebraska-Omaha, NE, USA.
Amy L
AL
Proskovec
Department of Neurological Sciences, University of Nebraska Medical Center (UNMC), Omaha, NE, USA.|Center for Magnetoencephalography, UNMC, Omaha, NE, USA.
Elizabeth
E
Heinrichs-Graham
Department of Internal Medicine, Division of Infectious Diseases, UNMC, Omaha, NE, USA.
Jennifer
J
O'Neill
Department of Neurology, University of North Carolina School of Medicine, Chapel Hill, NC, USA.
Kevin R
KR
Robertson
Department of Pharmacology and Experimental Neuroscience, UNMC,Omaha, NE, USA.
Howard S
HS
Fox
Department of Internal Medicine, Division of Infectious Diseases, UNMC, Omaha, NE, USA.
Susan
S
Swindells
D000367:Age Factors; D001921:Brain / Q000503:physiopathology* / Q000821:virology*; D001931:Brain Mapping; D016022:Case-Control Studies; D005260:Female; D015658:HIV Infections / Q000523:psychology* / Q000821:virology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D015225:Magnetoencephalography; D008297:Male; D008570:Memory, Short-Term; D009483:Neuropsychological Tests