Motor-to-sensory Transformation Mediates Auditory Hallucinations

Perceptual representation can be established through both bottom-up and top-down pathways.In auditory domain,for example,auditory representation can be generated by external acoustic stimuli.Similar auditory representations can also be established without external stimuli through motor-sensory transformation.This construction of similar auditory representations between motor-sensory transformation and external acoustic stimuli raises an important computational challenge: how the brain determines the source of information.However,from the reverse perspective,cognitive theory proposes that the abnormal monitoring of the representation source of sound perception may be the cause of auditory hallucination.Therefore,this study focuses on exploring the cognitive neural mechanism of auditory hallucinations,so as to further understand the monitoring mechanism of information sources in the brain from the perspective of psychiatry.Specifically,in this study,meta-analysis was used to introduce the hypothesis of the mechanism of motor-sensory transformation from the perspective of clinical treatment.Brain imaging studies were used to reveal the global monitoring of motor-sensory transformation,and EEG studies were used to detail the specific monitoring of motor-sensory transformation and its relationship with auditory hallucinations.Study one: In the theory of monitoring,the monitoring function in motor-tosensory transformation has also been mentioned.However,there are few studies directly intervention auditory hallucinations in motor sensory brain networks.Transcranial direct current stimulation(t DCS)can visually study the relationship between brain function and symptoms by targeting the brain regions associated with auditory hallucination.In order to explore the efficacy and potential mechanism of t DCS in treatment of auditory hallucinations,this study conducted a meta-analysis of previous studies before May 12,2018 of t DCS on auditory hallucinations.The results showed that the anodes on the left dorsolateral prefrontal lobe and the cathodes on the left temporoparietal junction had a potential therapeutic effect on auditory hallucinations.The results suggest that t DCS electrode stimulation of motor sensory transformation network may be an effective intervention technique to alleviate auditory hallucinations,and the functional abnormalities of motor sensory transformation may be one of the causes of auditory hallucinations from the perspective of treatment.Study two: The most general monitoring function for speech control is to start and stop speaking,and in some cases,stopping speaking in time is as important as starting speaking.Therefore,inhibition of speech is an important part of speech monitoring function,and whether this general speech monitoring function based on inhibition processing is missing in auditory hallucination patients.In this f MRI study,29 schizophrenia patients with auditory hallucinations and 31 healthy controls performed inhibitory control tasks of overt articulation and covert imagery articulation.The results showed that the neural networks involved in inhibition were basically the same in both overt and covert speech tasks.Compared with the healthy controls,auditory hallucinations patients showed slower stop-signal response time and lower right inferior frontal gyrus response,but higher activation in the inferior parietal gyrus supermarginal gyrus and angular gyrus in overt articulation tasks,and the normal right inferior frontal cortex response and lower supermarginal gyrus and angular gyrus response during the inhibition of imagery articulation task.These results suggest that inefficient processing of the right inferior frontal gyrus and the abnormal estimate of the SMG and AG mediates a deficiency of inhibitory control in motor-to-sensory transformation in auditory hallucination patients.Study three: In different stages of speech production,the articulatory motor system will send signals of different functions to the auditory system,Corollary discharge or Efference copy.The present study hypothesizes that a possible mechanism of auditory hallucinations is the abnormal evaluation of sensory signals by the motor system and the inability to mark whether the speech source is internal or external.That is,auditory hallucinations may be related to abnormal monitoring of specific information of the sensory system by the motor system.This hypothesis was tested by electroencephalogram experiments with an update delayed articulation task paradigm in 19 schizophrenic patients with auditory hallucinations and 16 schizophrenic patients without auditory hallucinations.Contrast with the result of healthy controls(19subjects),the results showed that the EC function of schizophrenic patients with and without auditory hallucinations was as normal as healthy controls,and the auditory representation could be established.However,the CD function of schizophrenic patients with auditory hallucinations was abnormal at different stages of motor-tosensory transformation,and the source monitoring of auditory representation was malfunctional.The results of this series of temporal dynamics and functional specificity indicate that the motor signals generated by motor-to-sensory transformation play a role in speech monitoring,and the abnormal motor-to-sensory transformation and its specific function of monitoring sensory signals may be the cause of auditory hallucinations.In summary,three studies were conducted to explore the monitoring function of auditory hallucinations in motor-to-sensory transformation.The intervention of physical stimulation-t DCS on auditory hallucinations has potential efficacy when the anode is located in motor cortex of the left dorsolateral prefrontal lobe and the cathode is located in sensory evaluation cortex of the left temporoparietal junction.In patients with auditory hallucinations,the general speech monitoring function based on inhibitory processing is missing,resulting in abnormal monitoring function of the source of sound.And the sensory system has an abnormal evaluation of specific signals in the motor system,resulting in an inability to specifically distinguish between internal and external speech responses.In this study,we obtained consistent evidence from the perspectives of motor-to-sensory transformation,supporting the hypothesis that the abnormal neural mechanism of information source monitoring is responsible for auditory hallucinations.