Cerebral blood flow relationships associated with a difficult tone recognition task in trained normal volunteers

Tone recognition is partially subserved by neural activity in the rightfrontal and primary auditory cortices. First we determined the brain areasassociated with tone perception and recognition. This study then examinedhow regional cerebral blood flow (rCBF) in these and other brain regionscorrelates with the behavioral characteristics of a difficult tonerecognition task. rCBF changes were assessed using H2(15)O positronemission tomography. Subtraction procedures were used to localizesignificant change regions and correlational analyses were applied todetermine how response times (RT) predicted rCBF patterns. Twelve trainednormal volunteers were studied in three conditions: REST, sensory motorcontrol (SMC) and decision (DEC). The SMC-REST contrast revealed bilateralactivation of primary auditory cortices, cerebellum and bilateral inferiorfrontal gyri. DEC-SMC produced significant clusters in the right middle andinferior frontal gyri, insula and claustrum; the anterior cingulate gyrusand supplementary motor area; the left insula/claustrum; and the leftcerebellum. Correlational analyses, RT versus rCBF from DEC scans, showed apositive correlation in right inferior and middle frontal cortex; rCBF inbilateral auditory cortices and cerebellum exhibited significant negativecorrelations with RT These changes suggest that neural activity in theright frontal, superior temporal and cerebellar regions shifts back andforth in magnitude depending on whether tone recognition RT is relativelyfast or slow, during a difficult, accurate assessment.