Middle and inferior temporal gyrus gray matter volume abnormalities in chronic schizophrenia: an MRI study

Abstract

Objective: The middle temporal gyrus and inferior temporal gyrus subserve language and semantic memory processing, visual perception, and multimodal sensory integration. Functional deficits in these cognitive processes have been well documented in patients with schizophrenia. However, there have been few in vivo structural magnetic resonance imaging (MRI) studies of the middle temporal gyrus and inferior temporal gyrus in schizophrenia.

Method: Middle temporal gyrus and inferior temporal gyrus gray matter volumes were measured in 23 male patients diagnosed with chronic schizophrenia and 28 healthy male subjects by using high-spatial-resolution MRI. For comparison, superior temporal gyrus and fusiform gyrus gray matter volumes were also measured. Correlations between these four regions and clinical symptoms were also investigated.

Results: Relative to healthy subjects, the patients with chronic schizophrenia showed gray matter volume reductions in the left middle temporal gyrus (13% difference) and bilateral inferior temporal gyrus (10% difference in both hemispheres). In addition, the patients showed gray matter volume reductions in the left superior temporal gyrus (13% difference) and bilateral fusiform gyrus (10% difference in both hemispheres). More severe hallucinations were significantly correlated with smaller left hemisphere volumes in the superior temporal gyrus and middle temporal gyrus.

Conclusions: These results suggest that patients with schizophrenia evince reduced gray matter volume in the left middle temporal gyrus and bilateral reductions in the inferior temporal gyrus. In conjunction with findings of left superior temporal gyrus reduction and bilateral fusiform gyrus reductions, these data suggest that schizophrenia may be characterized by left hemisphere-selective dorsal pathophysiology and bilateral ventral pathophysiology in temporal lobe gray matter.

FIGURE 1. Delineation of the Middle Temporal Gyrus and Inferior Temporal Gyrus^a

^a The red line illustrates the guideline extending the sulcal course of the superior temporal sulcus. The yellow line illustrates the guideline extending the sulcal course of the inferior temporal sulcus. The magnified views of slices A and B correspond to the green squares of the above images. Slice B shows a transitional area between the middle temporal gyrus and inferior temporal gyrus; they were separated by extending the guideline (the yellow dot) horizontally to the lateral surface of the temporal lobe.

FIGURE 2

Superior Temporal Gyrus, Middle Temporal Gyrus, Inferior Temporal Gyrus, and Fusiform Gyrus in a Coronal Slice and Three-Dimensional Reconstructions

FIGURE 3. Relative Volumes of the Middle Temporal Gyrus and Inferior Temporal Gyrus by Hemisphere in Male Patients With Chronic Schizophrenia (N=23) and Healthy Male Comparison Subjects (N=28)^a

^a Horizontal lines represent the mean relative volume.