Brief reportReduced frontotemporal functional connectivity in schizophrenia associated with auditory hallucinations
Introduction
Hypofrontality, particularly in dorsolateral prefrontal cortex (DLPFC), has been commonly but inconsistently found in schizophrenia Ebmeier et al 1995, Lawrie 1999, Weinberger and Berman 1996. Superior temporal gyrus (STG) abnormalities have been associated with auditory hallucinations (e.g., Shergill et al 2000), and some studies have suggested abnormal frontotemporal connectivity Fletcher et al 1996, Frith et al 1995, Yurgelun-Todd et al 1996. We have used fMRI to study schizophrenia patients and healthy control subjects while they completed a version of the Hayling Sentence Completion Task (Burgess and Shallice 1997). This task is sensitive to lesions of the frontal lobe (Burgess and Shallice 1996) and activates frontal and temporal regions (Nathaniel-James et al 1997). We tested the hypotheses that patients with schizophrenia would show less frontal activity and reduced frontotemporal connectivity, specifically between the left DLPFC and STG, compared with control subjects, and that reduced connectivity would be associated with auditory hallucinations.
Section snippets
Participants
The eight patients were clinically stable outpatients in Edinburgh, diagnosed with schizophrenia but no other major disorders according to DSM-IV criteria (American Psychiatric Association 1994) by two experienced clinicians (SML, ECJ). Three were men, and five were women; mean age was 28.6 years (SD 5.8), mean illness duration was 8 years (SD 6), and mean premorbid IQ (Nelson 1982) was 107.0 (SD 8.8). All patients were Caucasian and right-handed. All were medicated: three received clozapine,
Behavioral measures
The mean reaction times and word appropriateness scores for schizophrenia patients and control subjects are shown in Table 1. Both groups showed the expected increasing reaction times and word appropriateness scores with reduced constraint. Both measures showed group effects (p < .05 and p < .01 respectively) and condition (constraint) effects (both p < .01), but a nonsignificant interaction (both .05 <p < .1).
Sentence completion versus rest
Both groups showed activations of the bilateral DLPFC and the left middle/superior
Discussion
These schizophrenia patients were able to do the task, although they took longer and seemed to produce fewer appropriate words than did control subjects. We did not find hypofrontality while they performed this task nor any differential effect of varying constraint. Rather, we report direct evidence of reduced frontotemporal functional connectivity in schizophrenia, associated with auditory hallucinations but not delusions. We did, however, study a small group of high-functioning patients, only
Acknowledgements
The authors thank Majella Byrne, Richard Cosway, Julia Kestelman, and Robby Steel for help in recruiting the patients and control subjects, the MR physics and radiographer team at the Functional Imaging Laboratory in London, and the participating subjects. We also thank Norma Brearley for the careful preparation of the manuscript.
References (18)
- et al.
Response suppression, initiation and strategy use following frontal lobe lesions
Neuropsychologia
(1996) - et al.
The functional anatomy of verbal initiation and suppression using the Hayling Test
Neuropsychologia
(1997) Diagnostic and Statistical Manual of Mental Disorders
(1994)- et al.
Completion norms for 329 sentence contexts
Mem Cog
(1980) Vergleichende Lokalisationslehre der Grosshirnrinde in ihren Prinzipien dargestellt aug Grund dex Zellenbaues
(1909)- et al.
The Hayling and Brixton Tests
(1997) - et al.
Hypofrontality revisitedA high-resolution single photon emission computed tomography study in schizophrenia
J Neurol Neurosurg Psychiatry
(1995) - et al.
Local and distributed effects of apomorphine on fronto-temporal function in acute unmedicated schizophrenia
J Neurosci
(1996) - et al.
Regional brain activity in chronic schizophrenic patients during the performance of a verbal fluency task
Br J Psychiatry
(1995)
Cited by (478)
Abnormal brain network community structure related to psychological stress in schizophrenia
2023, Schizophrenia ResearchThe Neuroepigenome: Implications of Chemical and Physical Modifications of Genomic DNA in Schizophrenia
2022, Biological PsychiatryPerceptual reality monitoring: Neural mechanisms dissociating imagination from reality
2022, Neuroscience and Biobehavioral Reviews