Transcranial Direct Current Stimulation Does Not Increase Auditory False Perceptions in Healthy Participants

Area of Science:

• Neuroscience
• Cognitive Psychology
• Psychiatry

Background:

• Auditory hallucinations are a core symptom of psychotic disorders.
• A leading neurocognitive model suggests they stem from imbalanced brain activity in the left temporoparietal cortex and left dorsolateral prefrontal cortex.
• Understanding the neural underpinnings is crucial for developing effective treatments.

Purpose of the Study:

• To test a neurocognitive model of auditory hallucinations.
• To investigate the role of the left temporoparietal cortex and left dorsolateral prefrontal cortex in auditory false perceptions.
• To examine the effects of transcranial direct current stimulation (tDCS) on auditory false perceptions and their modulation by top-down and bottom-up factors.

Main Methods:

• 104 healthy participants completed a signal detection task to induce auditory false perceptions.
• Participants received either real or sham transcranial direct current stimulation (tDCS) with two different electrode montages.
• The study measured the rate of auditory false perceptions under varying conditions of expectation (top-down) and sensory input (bottom-up).

Main Results:

• Robust top-down and bottom-up interactions were observed, influencing the occurrence of auditory false perceptions.
• Neither the electrode montage nor the administration of real tDCS significantly modulated the rate of auditory false perceptions.
• The findings did not support the proposed hyperactive temporoparietal/hypoactive dorsolateral prefrontal cortex model.

Conclusions:

• Auditory verbal hallucinations appear to result from an interplay between bottom-up and top-down processes.
• The specific neurocognitive model tested, involving targeted brain stimulation, was not supported by the results.
• Potential reasons for the lack of tDCS effects, such as insufficient stimulation of target areas, warrant further investigation.