Article

Deficits in processing spatial information have been observed in
clinical populations who have abnormalities within the dopamine (DA) system. As
psychostimulants such as methamphetamine (MA) are particularly neurotoxic to the
dopaminergic system it was of interest to examine the performance of MA-dependent
individuals on a task of spatial attention. METHOD: 51 MA-dependent subjects and
22 age-matched non-substance abusing control subjects were tested on a Spatial
Stroop attention test. MR Spectroscopy (MRS) imaging data were analyzed from 32
MA abusers and 13 controls. RESULTS: No group differences in response time or
accuracy emerged on the behavioral task with both groups exhibiting equivalent
slowing when the word meaning and the spatial location of the word were in
conflict. MRS imaging data from the MA abusers revealed a strong inverse
correlation between NAA/Cr ratios in the Primary Visual Cortex (PVC) and spatial
interference (p=0.0001). Moderate inverse correlations were also seen in the
Anterior Cingulate Cortex (ACC) (p=0.02). No significant correlations were
observed in the controls, perhaps due to the small sample of imaging data
available (n=13). DISCUSSION: The strong correlation between spatial conflict
suppression and NAA/Cr levels within the PVC in the MA-dependent individuals
suggests that preserved neuronal integrity within the PVC of stimulant abusers
may modulate cognitive mechanisms that process implicit spatial information.
CI - Copyright (c) 2011 Elsevier Ltd. All rights reserved.

Langue : ANGLAIS