Amphetamine, haloperidol, and experience interact to affect rate of recovery after motor cortex injury.

Rats subjected to unilateral ablation of the motor cortex and placed on a narrow beam displayed transient contralateral paresis. An immediate and enduring acceleration of recovery was produced by a single dose of d-amphetamine given 24 hours after injury. This effect was blocked by haloperidol or by restraining the animals for 8 hours beginning immediately after amphetamine administration. A single dose of haloperidol given 24 hours after injury markedly slowed recovery. This effect was also blocked by restraining the animals.

Neuropsychological effects of Interferon Alfa-n3 treatment in asymptomatic human immunodeficiency virus-1-infected individuals.

Eighteen asymptomatic HIV-1-infected (HIV+) individuals were evaluated neuropsychologically before and during Interferon Alfa-n3 treatment. All 18 were evaluated twice, and 9 were evaluated three times. Analyses revealed few significant effects of treatment on cognitive, motor, and affective function. Improvements occurred over visits on measures of attention and appeared to reflect practice effects. Decrements occurred over visits on measures of procedural and supraspan learning. Examination of the data suggested that decrements were due to procedural artifacts and were not medication effects. In contrast to prior studies reporting significant neuropsychiatric side effects of interferon alpha treatment, few such effects occurred when HIV+ individuals were treated with Interferon Alfa-n3 and were evaluated neuropsychologically in a systematic manner.

Reaction time slowing in HIV-1-infected individuals: role of the preparatory interval.

Psychomotor speed and directed attention were evaluated in 83 human immunodeficiency virus-1-infected individuals (HIV+) and 50 HIV-1 seronegative (HIV-) control participants using simple and choice reaction time (RT) tasks. The simple RT task included 1- and 3-s, irregularly varied preparatory intervals (PI) between the warning and target lights. Relative to the HIV- group, simple and choice RT were significantly slowed in the HIV+ group. Further, again relative to the HIV- controls, the HIV+ group did not show expected faster RT with increased response preparation time in the simple RT task. This also occurred in some HIV+ subjects who did not have psychomotor slowing. These findings suggest that RT performance in HIV-1-infected individuals may reflect separate processes associated with psychomotor slowing and impaired ability to direct attention. Possible neural mechanisms associated with control of these processes are discussed.

Neuropsychological performance, mood, and complaints of cognitive and motor difficulties in individuals infected with the human immunodeficiency virus.

Seventy-nine military medical beneficiaries infected with human immunodeficiency virus (HIV+) and 27 HIV-seronegative control subjects (HIV-) completed a neuropsychological evaluation and a semistructured interview inquiring about difficulties in function. More HIV+ than HIV- subjects reported difficulties. HIV+ subjects reporting difficulties were significantly more likely to be deficient on attention, response speed, motor function, and memory than those not reporting difficulties. Findings for early-stage HIV+ subjects were similar. HIV+ individuals who complained of difficulties reported depression and anxiety symptoms significantly more frequently than those who did not complain, but these symptoms were not related to neuropsychological performance. Complaints of difficulties by HIV+ individuals may reflect either actual neuropsychological deficiency or mood disturbance, but the effects of each appear to be independent.

Progressive slowing of reaction time and increasing cerebrospinal fluid concentrations of quinolinic acid in HIV-infected individuals.

Neuropsychological functioning and cerebrospinal fluid concentrations of an endogenous neurotoxin, quinolinic acid (QUIN) were evaluated in 52 HIV-positive individuals (71% without constitutional symptoms) and 33 HIV-seronegative controls (including 15 psychiatric patients with adjustment disorders). Although the HIV-positive subjects did not differ from controls on standard neuropsychological tests, simple and choice reactions times (RT) were slow at initial evaluation (P less than 0.01) and became progressively slower at 6-month re-evaluation (P less than 0.05). Cerebrospinal fluid (CSF) QUIN was elevated at initial evaluation and increased during the 6-month interval (P less than 0.05). Moreover, during this 6-month interval, progressive slowing of RT was highly correlated with increasing levels of CSF QUIN (r = 0.85, df = 15, P less than 0.0001) but not with changes in mood, constitutional symptoms, or CD4 cell count. These findings suggest that RT may provide a sensitive behavioral measure of relatively early central nervous system involvement in HIV-infected individuals and that QUIN may play an important role in the pathogenesis of HIV-related neurological dysfunction.

Working memory in individuals with HIV infection.

The central executive component (CE) of Baddeley's working memory model (Baddeley, 1992) was evaluated in 26 asymptomatic human immunodeficiency virus-infected individuals (HIV+) and 23 HIV-control subjects using a dual-task working memory paradigm. The HIV+ and HIV- groups showed an equivalent reduction in performance on both the primary task (visual vigilance) and the secondary task (letter span) when they were performed concurrently relative to when either task was performed alone. This result suggested normal CE functioning in these HIV+ subjects. In contrast, the HIV+ subjects had significantly longer response latencies on reaction time measures relative to the HIV- control group. These findings indicated that slowed processing in early stage HIV-infected individuals is not associated with a working memory deficit.