Spatial inhibition and the visual cortex: a magnetic resonance spectroscopy imaging study.

Area of Science:

• Neuroscience
• Cognitive Psychology
• Neuroimaging

Background:

• Dopamine system abnormalities are linked to spatial information processing deficits.
• Psychostimulants like methamphetamine (MA) are neurotoxic to the dopamine system.

Purpose of the Study:

• To investigate spatial attention performance in MA-dependent individuals.
• To explore the relationship between brain metabolites and spatial attention in MA users.

Main Methods:

• 51 MA-dependent subjects and 22 controls completed a Spatial Stroop attention test.
• MR Spectroscopy (MRS) analyzed brain metabolites in 32 MA abusers and 13 controls.

Main Results:

• No behavioral differences were observed between MA users and controls on the Spatial Stroop task.
• MA abusers showed an inverse correlation between NAA/Cr ratios in the Primary Visual Cortex (PVC) and spatial interference.
• A similar inverse correlation was noted in the Anterior Cingulate Cortex (ACC).

Conclusions:

• Preserved neuronal integrity in the PVC of MA-dependent individuals may modulate the processing of implicit spatial information.
• NAA/Cr levels in the PVC are associated with spatial conflict suppression in stimulant abusers.