Suppression of Deactivation of Working Memory and Promotion of Activation of Sustained Attention in the Default Mode Network Are Affected by Schizotypy in a Large Sample of Nonclinical Subjects

Abstract

Introduction: Schizotypy is a personality trait characterized by subclinical expression of the signs and symptoms of schizophrenia. Maladaptive schizotypy is given the clinical designation of schizotypal personality disorder. Previous studies have shown that functional disturbance of the default mode network (DMN) is associated with maladaptive schizotypy. Working memory impairment is a particularly common feature of maladaptive schizotypy and schizophrenia. As these characteristics can also be observed in the healthy population, our purpose was to identify the neural correlates of schizotypy during sustained attention tasks and working memory tasks in nonclinical subjects.

Methods: We recruited 409 healthy individuals (251 men and 158 women; 20.7 ± 1.8 [SD] years of age) and determined their schizotypy scores using the Schizotypal Personality Questionnaire. We used a typical functional MRI (fMRI) task under 0-back and 2-back conditions. Corrections for multiple comparisons were performed via the threshold-free cluster enhancement method with a familywise error-corrected threshold of p < 0.0167 (0.05/3) at the whole-brain level, including the cerebellum.

Results: Suppression of deactivation of the DMN (the medial prefrontal cortex (mPFC), the posterior cingulate cortex, the inferior parietal lobule, and the middle temporal gyrus) in the working memory (2-back > rest) task and promotion of activation during the sustained attention (0-back > rest) task were associated with schizotypy scores. Among the schizotypy subscores, cognitive-perceptual deficits were significantly related only to the left precuneus, the mPFC, and the superior temporal gyrus for the 2-back > 0-back contrast; to the left precuneus and the bilateral mPFC for the 2-back > rest contrast; and to the left superior temporal cortex and the right precuneus for the 0-back > rest contrast within the DMN.

Conclusion: Disturbance of the DMN is related to the degree of schizotypy, especially to the degree of cognitive‒perceptual deficits, even in nonclinical subjects.

Keywords: default mode network; schizotypy; sustained attention; working memory.

FIGURE 1

Distribution of total schizotypy scores for males and females. The histograms show the distributions of schizotypy scores in males and females.

FIGURE 2

Associations between brain activity during the working memory task and schizotypy scores. Suppression of deactivation in the left superior temporal gyrus (a1), the bilateral anterior cingulate cortex (b1), the right parietal operculum (c1), and the right superior parietal lobule (d1) is associated with schizotypy score during the 2‐back task. The results were obtained using a significance threshold of p < 0.05/3, corrected for multiple comparisons based on 5000 permutations using threshold‐free cluster enhancement (TFCE) scores. All the results are overlaid on a “single‐subject T1” SPM12 image. The scatter plots show the associations between each cluster and the eigenvector values of the beta estimates in each cluster (a2, b2, c2, and d2).

FIGURE 3

Associations between brain activity during the sustained attention task and schizotypy scores. Brain suppression of activation in the inferior cortex via the middle to superior temporal gyri (a1), the bilateral superior frontal gyri (b1), and the right middle cingulate cortex (c1) during the 0‐back task was associated with schizotypy score. The results were obtained using a significance threshold of p < 0.05/3, corrected for multiple comparisons based on 5000 permutations using threshold‐free cluster enhancement (TFCE) scores. All the results are overlaid on a “single‐subject T1” SPM12 image. The scatter plots show the association between each cluster and the mean beta estimates in each cluster; this association is more robust to heterogeneity of response within a cluster (a2, b2, and c2).

FIGURE 4

Associations between brain activity during the working memory task and cognitive–perceptual deficits subscores. Cognitive–perceptual deficits subscores were significantly correlated with beta estimates for the “2‐back > 0‐back” (a1), “2‐back < 0‐back” (a2), “2‐back > rest” contrast (b1), “2‐back < rest” (b2), “0‐back > rest” (c1), and “0‐back < rest” (c2) contrast. The results were obtained using a significance threshold of p < 0.05/3, corrected for multiple comparisons based on 5000 permutations using threshold‐free cluster enhancement (TFCE) scores. All the results are overlaid on a “single‐subject T1” SPM12 image.