[Functional magnetic resonance in the evaluation of the activity of the anterior cingulate cortex using Stroop's paradigm]. / Resonancia magnética funcional en la evaluación de la actividad del cingulado anterior mediante el paradigma de Stroop.

INTRODUCTION: Stroop s paradigm has been used to evaluate the anterior attention system which regulates the inhibitory capacity of automatic responses. Functional neuroimaging techniques have shown a preponderant role for the anterior cingulate cortex in carrying out this paradigm. OBJECTIVE: To evaluate the activity of the anterior cingulate cortex in view of its clinical importance in the study of neurological and psychiatric disorders. PATIENTS AND METHODS: Eleven healthy volunteers took part in the study. The functional images were analyzed using the software SPM99 and by second order individual and group analysis. RESULTS: Initial local analysis showed activation in the right anterior cingulated cortex (Brodmann s area 32) and left central (areas 31 and 23); caudate nucleus (right body and left tail) and thalamus (bilateral). Overall there was significant activation of the left hemisphere, in areas 44 (Broca s area), 7, 40 (supra marginal gyrus and insular cortex, and in the right hemisphere in area 19. In spite of this there was great individual variation. CONCLUSIONS: The overall results are concordant with complex functional connections for attention and the control of automatic responses. In our study the anterior cingulated cortex was not selectively activated. The activation of the thalamus and caudate nucleus may be explained by their involvement in the frontostriatal circuits. The lack of individual consistency may be due to different personal cognitive styles of resolving conflicts. According to our results, Stroop s paradigm would not be clinically useful for showing good or bad functioning of the anterior cingulated cortex.