Background: Selective declarative memory processes are differentially compromised in chronic alcoholism (ALC) and HIV infection (HIV) and likely reflect neuropathology associated with each condition: frontocerebellar dysfunction in ALC and frontostriatal dysfunction in HIV infection. Evidence for disease overlap derives from observed exacerbated impairments in these declarative memory processes in ALC-HIV comorbidity. Less is known about nondeclarative memory processes in these disease conditions. Examination of visuomotor learning in chronic ALC and HIV infection could provide insight into the differential and combined contribution of selective disease-related injury to visuomotor procedural memory processes.
Methods : We examined component processes of visuomotor learning and retention on the rotary pursuit task in 29 ALC, 23 HIV, 28 ALC + HIV, and 20 control subjects. Participants were given 4 rotary pursuit learning sessions over 2 testing days, typically separated by 1 week, to assess visuomotor learning and retention patterns. Ancillary measures of simple motor, psychomotor, explicit memory, and balance abilities were administered to test which component processes independently predicted visuomotor learning.
Results : All clinical groups showed visuomotor learning across rotary pursuit testing sessions, despite impairment in visuomotor speed in the HIV groups and impairment in explicit memory and psychomotor speed in the alcohol groups. The 2 alcoholic groups showed retention and consolidation over time (i.e., improved performance without further training), whereas the HIV-infected group showed learning and retention but no consolidation effect. The comorbid group shared impairments associated with the ALC-only group (explicit memory and psychomotor speed) and the HIV-only group (visuomotor speed), although there was no clear compounded effect of alcohol and HIV infection on visuomotor learning performance.
Conclusions: This study supports the hypothesis that ALC and HIV infection exert differential effects on components of visuomotor procedural learning. Further, the results provide behavioral evidence for dissociable influences of frontocerebellar and frontostriatal disruption to visuomotor procedural learning and retention.