title: Spatial inhibition and the visual cortex: a magnetic resonance spectroscopy imaging study.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Psychiatry and Behavioral Sciences, University of California, Davis, CA, United States; Imaging Research Center, University of California, Davis, CA, United States. Electronic address: resalo@ucdavis.edu.
authors.forename: R
authors.initials: R
authors.lastname: Salo
authors.affiliation: Department of Psychiatry and Behavioral Sciences, University of California, Davis, CA, United States; Imaging Research Center, University of California, Davis, CA, United States.
authors.forename: T E
authors.initials: TE
authors.lastname: Nordahl
authors.affiliation: Imaging Research Center, University of California, Davis, CA, United States; Department of Biomedical Engineering, University of California, Davis, CA, United States.
authors.forename: M H
authors.initials: MH
authors.lastname: Buonocore
authors.affiliation: Imaging Research Center, University of California, Davis, CA, United States.
authors.forename: Y T
authors.initials: YT
authors.lastname: Natsuaki
authors.affiliation: Kaiser Chemical Dependence Recovery Program, Sacramento, CA, United States.
authors.forename: C D
authors.initials: CD
authors.lastname: Moore
authors.affiliation: Kaiser Chemical Dependence Recovery Program, Sacramento, CA, United States.
authors.forename: C
authors.initials: C
authors.lastname: Waters
authors.affiliation: Department of Psychiatry and Behavioral Sciences, University of California, Davis, CA, United States.
authors.forename: M H
authors.initials: MH
authors.lastname: Leamon
mesh_terms: D000328:Adult; D019969:Amphetamine-Related Disorders / Q000473:pathology / Q000503:physiopathology; D000704:Analysis of Variance; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D001288:Attention / Q000502:physiology*; D001931:Brain Mapping; D016022:Case-Control Studies; D002794:Choline / Q000378:metabolism; D003401:Creatine / Q000378:metabolism; D005260:Female; D006801:Humans; D007266:Inhibition, Psychological; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010775:Photic Stimulation; D011930:Reaction Time / Q000502:physiology; D013028:Space Perception / Q000502:physiology*; D013223:Statistics as Topic; D014793:Visual Cortex / Q000378:metabolism / Q000502:physiology*
chemical_list: D001224:Aspartic Acid; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline