Abnormalities of thalamic activation and cognition in schizophrenia

Objective: Functional and structural magnetic resonance imaging (MRI) was used to investigate relationships among structure, functional activation, and cognitive deficits related to the thalamus in individuals with schizophrenia and healthy comparison subjects. Method: Thirty-six schizophrenia subjects and 28 healthy comparison subjects matched by age, gender, race, and parental socioeconomic status underwent structural and functional MRI while performing a series of memory tasks, including an N-back task (working memory), intentional memorization of a series of pictures or words (episodic encoding), and a yes/no recognition task. Functional activation magnitudes in seven regions of interest within the thalamic complex, as defined by anatomical and functional criteria, were computed for each group. Results: Participants with schizophrenia exhibited decreased activation within the whole thalamus, the anterior nuclei, and the medial dorsal nucleus. These nuclei overlap with subregions of the thalamic surface that the authors previously reported to exhibit morphological abnormalities in schizophrenia. However, there were no significant correlations between specific dimensions of thalamic shape variation (i.e., eigenvectors) and the activation patterns within thalamic regions of interest. Better performance on the working memory task among individuals with schizophrenia was significantly associated with increased activation in the anterior nuclei, the centromedian nucleus, the pulvinar, and the ventrolateral nuclei. Conclusions: These results suggest that there are limited relationships between morphological and functional abnormalities of the thalamus in schizophrenia subjects and highlight the importance of investigating relationships between brain structure and function.