Frontotemporal cerebral blood flow change during executive and declarative memory tasks in schizophrenia: a positron emission tomography study

Abstract

Schizophrenia affects prefrontal and temporal-limbic networks. These regions were examined by contrasting regional cerebral blood flow (rCBF) during executive (Wisconsin Card Sorting Test [WCST]), and declarative memory tasks (Paired Associate Recognition Test [PART]). The tasks, and a resting baseline, were administered to 15 patients with schizophrenia and 15 healthy controls during 10 min positron emission tomography 15O-water measures of rCBF. Patients were worse on both tasks. Controls activated inferior frontal, occipitotemporal, and temporal pole regions for both tasks. Similar results were obtained for controls matched to level of patient performance. Patients showed no activation of hypothesized regions during the WCST and activated the dorsolateral prefrontal cortex during the PART. On the PART, occipitotemporal activation correlated with better performance for controls only. Better WCST performance correlated with CBF increase in prefrontal regions for controls and in the parahippocampal gyrus for patients. Results suggest that schizophrenia may involve a breakdown in the integration of a frontotemporal network that is responsive to executive and declarative memory demands in healthy individuals.

Figure 1

Placement of representative regions of interest (ROIs) on MRI images. ROI labels are abbreviated as follows (regions included in the main analysis are in boldface): SF = superior frontal; DL = dorsolateral prefrontal; DM = dorsomedial prefrontal; MF = mid-frontal; IF = inferior frontal; SM = sensorimotor; SP = superior parietal; SG = supramarginal gyrus; OM = occipital-medial; OL = occipital-lateral; LI = lingual gyrus; FG = fusiform gyrus; OT = occipitotemporal; ST = superior temporal; MT = mid-temporal; IT = inferior temporal; TP = temporal pole; PH = parahippocampal gyrus; HI = hippocampus; AM = amygdala; IN = insula; OF = orbital frontal; RG = rectal gyrus; CA = cingulate gyrus-anterior, CG = cingulate gyrus; CP = cingulate gyrus-posterior, C1 = corpus callosum-anterior; C2 = corpus callosum-posterior, CN = caudate nucleus; LM = lenticular-medial (globus pallidus); LL = lenticula-lateral (putamen); MB = mammillary body; TH = thalamus; MI = midbrain; PO = pons; CE = cerebellum.

Figure 2

Mean (±SEM) relative change in regional cerebral blood flow (rCBFΔ; baseline subtracted) for Paired Associate Recognition Test (PART; top graph) and Wisconsin Card Sorting Test (WCST; bottom graph) for 15 demographically matched controls (open bars) and 15 patients with schizophrenia (shaded bars). SF = superior frontal; DL = dorsolateral prefrontal; DM = dorsomedial prefrontal; IF = inferior frontal; OT = occipitotemporal; MT = mid-temporal; IT = inferior temporal; TP = temporal pole; PH = parahippocampal gyrus; HI = hippocampus; AM = amygdala; OF = orbital frontal. *p < .05, **p < .005 controls; +p < .05 patients; all two-tailed.

Figure 3

Mean (±SEM) relative change in regional cerebral blood flow (rCBFΔ; baseline subtracted) for Paired Associate Recognition Test (PART; top graph) and Wisconsin Card Sorting Test (WCST; bottom graph) for 15 demographically matched controls (open bars) and 15 performance matched controls (shaded bars). SF = superior frontal; DL = dorsolateral prefrontal; DM = dorsomedial prefrontal; IF = inferior frontal; OT = occipitotemporal; MT = mid-temporal; IT = inferior temporal; TP = temporal pole; PH = parahippocampal gyrus; HI = hippocampus; AM = amygdala; OF = orbital frontal. *p < .05 demographically matched controls; +p < .05 performance-matched controls.

Figure 4

Scatter plot of relationship between Paired Associate Recognition Test (PART) regional cerebral blood flow change from baseline in the occipitotemporal region (rCBFΔ, x-axis) and PART percent correct performance (PARTPCOR, y-axis) for 15 demographically matched healthy controls.

Figure 5

Scatter plots of relationship between Wisconsin Card Sorting Test (WCST) number of categories (WCSTCAT, y-axis) and regional cerebral blood flow change from baseline in superior frontal region (rCBFΔ, x-axis) for 15 demographically matched healthy controls (left graph) and rCBFΔ in the parahippocampal gyrus for 15 patients (right graph).

Figure 6

Mean (±SEM) relative regional cerebral blood flow change (rCBFΔ; baseline subtracted) for all 36 regions of interest (ROIs) for Paired Associate Recognition Test (PART; top graph) and Wisconsin Card Sorting Test (WCST; bottom graph) for 15 demographically matched controls (open bars) and 15 patients with schizophrenia (shaded bars). SF = superior frontal; DL = dorsolateral prefrontal; DM = dorsomedial prefrontal; MF = mid-frontal; IF = inferior frontal; SM = sensorimotor; SP = superior parietal; SG = supramarginal gyrus; OM = occipital-medial; OL = occipital-lateral; LI = lingual gyrus; FG = fusiform gyrus; OT = occipitotemporal; ST = superior temporal; MT = mid-temporal; IT = inferior temporal; TP = temporal pole; PH = parahippocampal gyrus; HI = hippocampus; AM = amygdala; IN = insula; OF = orbital frontal; RG = rectal gyrus; CA = cingulate gyrus-anterior; CG = cingulate gyrus; CP = cingulate gyrus-posterior; Cl = corpus callosum-anterior; C2 = corpus callosum-posterior; CN = caudate nucleus; LM = lenticular-medial (globus pallidus); LL = lenticula-lateral (putamen); MB = mammillary body; TH = thalamus; MI = midbrain; PO = pons; CE = cerebellum; PAR = parietal; OCC = occipital; CC = corpus callosum; BG = basal ganglia; DIE = diencephalon; BS = brainstem. Regions that were analyzed in the primary analysis are in bold. *p < .05 controls; +p < .05 patients; all two-tailed.

Figure 7

Statistical parametric map projections (SPM |z|) of areas of significant activation when resting baseline was subtracted from Paired Associate Recognition Test (PART) and Wisconsin Card Sorting Test (WCST) conditions. The top two images (A,B) are for PART minus baseline subtractions for 13 demographically matched controls (CT) and 13 patients (PT), respectively. The bottom two images (C,D) present control and patient data for the WCST minus baseline subtraction. Areas of activation (p < .005, uncorrected) are illustrated in the Talairach coordinate system for sagittal, coronal, and transverse planes.