Facilitation of sensorimotor temporal recalibration mechanisms by cerebellar tDCS in patients with schizophrenia spectrum disorder and healthy subjects

Core symptoms in patients with schizophrenia spectrum disorder (SSD), such as hallucinations or ego-disturbances, have been associated with a failure of the forward model to adequately predict the sensory outcomes of self-generated actions. Importantly, depending on the requirements of the environment, forward model predictions must also be able to recalibrate flexibly, for example to account for additional delays between action and outcome. In this study, we aimed to investigate whether non-invasive brain stimulation via transcranial direct current stimulation (tDCS) can be used to improve these sensorimotor temporal recalibration mechanisms in patients and in healthy subjects. While receiving tDCS on the cerebellum, temporo-parietal junction (TPJ), supplementary motor area (SMA), or sham stimulation, patients with SSD and healthy control subjects were repeatedly exposed to delays between actively elicited or passively performed button press movements and auditory sensory outcomes. Effects of this procedure on temporal perception were assessed with a delay detection task. We found similar sensorimotor temporal recalibration effects in both SSD and healthy subjects. Furthermore, cerebellar tDCS facilitated recalibration effects in both groups. Our findings indicate that sensorimotor recalibration mechanisms may be preserved in SSD and highlight the importance of the cerebellum in both patients and healthy subjects for this process. Our results suggest that cerebellar tDCS could be a promising tool for addressing deficits in action-outcome monitoring and related adaptive sensorimotor processes in SSD, and potentially alleviating associated symptoms.