Mechanistic account of the left auditory cortex for tone-matching in schizophrenia: A pilot transcranial random noise stimulation (tRNS) sham-controlled study.

OBJECTIVE: Deficits in the ability to match tones following brief delay and their contribution to higher-order cognitive alterations have been repeatedly documented in schizophrenia. The aim was to explore if left fronto-temporal high-frequency transcranial random noise stimulation (hf-tRNS), with electrodes placed over brain regions involved in tone-matching would significantly modulate performances in participants with schizophrenia. METHODS: In a randomized, double-blind sham-controlled study, 10 participants with schizophrenia were allocated to receive ten sessions of either active or sham hf-tRNS. The anode was placed over the left prefrontal cortex and the cathode over the left temporoparietal junction. A tone-matching task was administered before and after the hf-tRNS. RESULTS: We calculated the changes in tone-matching performance before and after hf-tRNS session in each group. A significant between-group difference was observed for the difficult tone-matching conditions (W= 14.500, p = 0.032), with tone-matching improvement in the sham group and no improvement in the active group. DISCUSSION: hf-tRNS could disrupt the test-retest learning effect in the tone-matching task in individuals with schizophrenia. It is likely that this disruption resulted from cathodal-induced inhibition of the functional coupling between auditory cortical areas that correlates with tone-matching performance in patients. CONCLUSION: The findings contribute to our understanding of hf-tRNS effects on early auditory processing in schizophrenia.

Basic auditory processing and its relationship with symptoms in patients with schizophrenia: A systematic review.

Processing of basic auditory features, one of the earliest stages of auditory perception, has been the focus of considerable investigations in schizophrenia. Although numerous studies have shown abnormalities in pitch perception in schizophrenia, other basic auditory features such as intensity, duration, and sound localization have been less explored. Additionally, the relationship between basic auditory features and symptom severity shows inconsistent results, preventing concrete conclusions. Our aim was to present a comprehensive overview of basic auditory processing in schizophrenia and its relationship with symptoms. We conducted a systematic review according to the PRISMA guidelines. PubMed, Embase, and PsycINFO databases were searched for studies exploring auditory perception in schizophrenia compared to controls, with at least one behavioral task investigating basic auditory processing using pure tones. Forty-one studies were included. The majority investigated pitch processing while the others investigated intensity, duration and sound localization. The results revealed that patients have a significant deficit in the processing of all basic auditory features. Although the search for a relationship with symptoms was limited, auditory hallucinations experience appears to have an impact on basic auditory processing. Further research may examine correlations with clinical symptoms to explore the performance of patient subgroups and possibly implement remediation strategies.