Decreased frontal activation of schizophrenics during stimulation with the continuous performance test—A functional magnetic resonance imaging study

Abstract

Summary -The Continuous Performance Test (CPT) has become an essential constituent of the neuropsychological investigation of schizophrenia. Also, a vast number of brain imaging studies, mostly PET investigations, have employed the CPT as a cognitive challenge and established a relative hypofrontality in schizophrenics compared to controls. The aim of the present investigation was to clarify whether this predescribed hypofrontality could also be verified using functional magnetic resonance imaging (fMRI). 20 healthy volunteers and 14 schizophrenics on stable neuroleptic medication were included. Imaging was performed using the CPT-double-T-version and a clinical 1.5 T MRI-scanner with a single slice technique and a T 2 *-weighted gradient-echo-sequence. The schizophrenics exhibited a decreased activation in the right mesial prefrontal cortex, the right cingulate and the left thalamus compared to controls. These results obtained by fMRI are discussed in relation to published findings using PET. © Elsevier, Paris functional magnetic resonance imaging / schizophrenia / attention / hypofrontality

Impact of Catechol-O-Methyltransferase on Prefrontal Brain Functioning in Schizophrenia Spectrum Disorders

“…Based on such findings, the NGA has been suggested to be an electrophysiological correlate of cognitive response control and a neurophysiological marker of ACC function, even though other brain regions, particularly within the prefrontal cortex, are likely to be involved as well (eg Ford et al, 2004). In accordance with the hypofrontality concept, schizophrenic patients were found to have a significantly diminished NGA (Fallgatter and Mueller, 2001) and a reduced activation of the ACC during Nogo conditions (Fallgatter et al, 2003), findings that are again largely in line with electrophysiological (Kopp and Rist, 1999;Strandburg et al, 1999;Kiehl et al, 2000;Weisbrod et al, 2000;Mathalon et al, 2002) and neuroimaging data (Volz et al, 1999;Carter et al, 2001;Rubia et al, 2001;Laurens et al, 2003).…”

Guanfacine Treatment of Cognitive Impairment in Schizophrenia

“…Although performance on the spatial working memory test (Arnsten and Goldman-Rakic 1985;Avery et al 2000; has been clearly linked to the integrity of frontal lobe functions, it may be argued that the improvement in performance on CPT reaction time observed in this study was related to guanfacine's effect on psychomotor speed and not a change in frontal lobe function. However, neuroimaging has correlated poor CPT performance with reduced frontal activity in schizophrenic patients (Buchsbaum et al 1990;Volz et al 1999). In addition, reaction tine performance on the CPT has been validated as an index of attention (Reinvang 1998).…”

Too Little and Too Much: Hypoactivation and Disinhibition of Medial Prefrontal Cortex Cause Attentional Deficits

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