Investigating the association of ventral and dorsal striatal dysfunction during reward anticipation with negative symptoms in patients with schizophrenia and healthy individuals

Background Negative symptoms are a core feature of schizophrenia and also found in healthy individuals in subclinical forms. According to the current literature the two negative symptom domains, apathy and diminished expression may have different underlying neural mechanisms. Previous observations suggest that striatal dysfunction is associated with apathy in schizophrenia. However, it is unclear whether apathy is specifically related to ventral or dorsal striatal alterations. Here, we investigated striatal dysfunction during reward anticipation in patients with schizophrenia and a non-clinical population, to determine whether it is associated with apathy. Methods Chronic schizophrenia patients (n = 16) and healthy controls (n = 23) underwent an event- related functional MRI, while performing a variant of the Monetary Incentive Delay Task. The two negative symptom domains were assessed in both groups using the Brief Negative Symptoms Scale. Results In schizophrenia patients, we saw a strong negative correlation between apathy and ventral and dorsal striatal activation during reward anticipation. In contrast, there was no correlation with diminished expression. In healthy controls, apathy was not correlated with ventral or dorsal striatal activation during reward anticipation. Conclusion This study replicates our previous findings of a correlation between ventral striatal activity and apathy but not diminished expression in chronic schizophrenia patients. The association between apathy and reduced dorsal striatal activity during reward anticipation suggests that impaired action-outcome selection is involved in the pathophysiology of motivational deficits in schizophrenia

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Clinical and demographic characteristics.

<p>Clinical and demographic characteristics.</p

Correlations of the two negative symptom dimensions with VS activation during reward anticipation.

<p>Bivariate Spearman correlation of (A) apathy (r_s = -.59, p = .02) and (B) diminished expression (<i>r</i>_<i>s</i> = .30 p = .26) with percent signal change in the ventral striatum in patients with schizophrenia. Bivariate Spearman correlation of (C) apathy (r_s = -.06, p = .79) and (D) diminished expression (r_s = -.20, p = .35) with percent signal change in the ventral striatum in healthy controls. BNSS = Brief Negative Symptom Scale.</p

Correlations of the two negative symptom dimensions with DS activation during reward anticipation.

<p> Bivariate Spearman correlation of (A) apathy (<i>r</i>_<i>s</i> = -.56, p = .02) and (B) diminished expression (<i>r</i>_<i>s</i> = .30, p = .26) with percent signal change in the dorsal striatum in patients with schizophrenia. Bivariate Spearman correlation of (C) apathy (r_s = -.01, p = .96) and (D) diminished expression (r_s = -.39, p = .07) with percent signal change in the dorsal striatum in healthy controls. BNSS = Brief Negative Symptom Scale.</p

Behavioral results of the variant of the Monetary Incentive Delay Task.

<p>Behavioral results of the variant of the Monetary Incentive Delay Task.</p

Schematic illustration of the variant of Monetary Incentive Delay Task (MID) (adapted from Kirschner et al. [6]).

<p>In each trial, participants saw 1 of 3 cues, indicating the amount of money to be won. After a delay period, participants had to identify an outlier from an array of 3 circles by pressing a correct button (either left or right). Immediately after a correct button press, participants were informed via visual feedback about the amount of money they had won during the current trial. A red horizontal line on the column ranging from the minimal amount (0 CHF) to the maximal win amount (2.0 CHF) indicated the precise amount of money won in each trial.</p

Summary of the main findings.

<p>Correlations between the striatal signal during reward anticipation and dimensions of negative symptoms in patients with chronic schizophrenia and healthy participants.</p