Metabolic brain pattern of sustained auditory discrimination

Abstract

Positron emission tomography of [18F]-2-fluorodeoxyglucose was used to assess the functional brain activity of normal subjects while performing auditory discrimination (CPT), while receiving an identical set of tones as in CPT, but with the instructions that they were background noise, or while at rest. The present study: (1) confirms earlier findings of an association between the functional activity of the right midprefrontal cortex and the performance of auditory discrimination, (2) localizes this increase in right prefrontal cortex activity to the middle prefrontal gyrus; and (3) provides a framework of specific testable hypotheses for the evaluation of the importance of certain limbic and paralimbic areas in the biological determination of sustained attention to be addressed in future studies. The framework accounts for the now confirmed finding that the middle cingulate has lower metabolic activity in CPT than at rest, and new findings of alterations in temporal lobe processing of tones in response to attention.

Abnormalities in the Distributed Network of Sustained Attention Predict Neuroleptic Treatment Response in Schizophrenia

“…Sustained attention on continuous performance tasks (CPT) has served as a laboratory model of this failure in positron emission tomography (PET) studies of regional glucose metabolic rates (Cohen et al 1988a). In PET studies (Buchsbaum et al 1990(Buchsbaum et al , 1992aCohen et al 1987), medication-withdrawn and neuroleptic-naive patients with schizophrenia performing CPT, and in our study, regardless of performance and medication status, were found to have abnormally low functional activity of the midprefrontal cortex area that served as the biological determinant of this task in normal controls (Cohen et al 1987(Cohen et al , 1988c(Cohen et al , 1992. These studies, although consistent with earlier data from a variety of methods on the importance of the right prefrontal cortex in attentional processes (Mesulam 1981), and subsequent and concurrent other PET studies utilizing cerebral blood flow as a measure of activation (Posner and Petersen 1990), were all performed at low resolutions and most, if not all, with calculated attenuation corrections.…”

“…This expectation was borne out in a new study of normal controls performing CPT (Cohen et al 1992) that provided evidence of basal ganglia involvement in the task per-formance of normal controls that had previously gone undetected. The new findings were consistent with earlier animal and human studies of basal ganglia involvement in attentional processes (see Mesulam, 1981 andCohen et al, 1992 for references).…”

“…This expectation was borne out in a new study of normal controls performing CPT (Cohen et al 1992) that provided evidence of basal ganglia involvement in the task per-formance of normal controls that had previously gone undetected. The new findings were consistent with earlier animal and human studies of basal ganglia involvement in attentional processes (see Mesulam, 1981 andCohen et al, 1992 for references). The importance of this finding for understanding the phenotypic expression of schizophrenia attained greater significance as a result of the findings of Buchsbaum and his colleagues (Buchsbaum et al 1992a).…”

“…An accuracy measure LNCPT, calculated as ln [HITS/ (FA ϩ 1)], is used to correct for subject response bias. LNCPT is highly correlated to the more usual modeldependent signal analysis parameter d ' (Cohen et al 1992), and has been demonstrated to correlate with right midprefrontal cortex activity (Cohen et al 1992), and to be sensitive to a neuropsychiatric disorder with attention abnormalities (Matochik et al 1996) as well as a drug known to affect attention processes . Because of technical difficulties, CPT response records were only recoverable for 34 of the normal controls and 14 of the schizophrenic patients limiting the number of subjects that could be used in these analyses relating to CPT performance.…”

The Brain Metabolic Patterns of Clozapine- and Fluphenazine-Treated Female Patients with Schizophrenia Evidence of a Sex Effect

“…To extract regional glucose metabolic rates, 60 rectangular boxes were located in five standard planes (plane A, 94 mm above CM line; plane B, 81 mm above CM line; plane C, 67 mm above CM line; plane D, 53 mm above CM line; plane E, 40 mm above CM line) chosen from one of the four seven-plane scan sets (Cohen et al 1988a;Cohen et al 1992;Semple et al 1993). Anatomical structures were judged as contained within these regions according to the human brain atlas of Matsui and Hirano (1978).…”