Functional connectivity corresponding to the tonotopic differentiation of the human auditory cortex

Improvement of symptoms in children with autism by TOMATIS training: a cross-sectional and longitudinal study

Introduction

Autism spectrum disorder (ASD) is a neurological condition that is marked by deficits in social interaction, difficulty expressing oneself, lack of enthusiasm, and stereotypical conduct. The TOMATIS training method is an effective music therapy for children with ASD for its individually developed programs to improve behavioral deficits.

Methods

The research employed both longitudinal and crosssectional designs.

Results

In the cross-sectional study, the experimental group showed significant improvement in symptoms after TOMATIS training compared to the control group of children with ASD. The results validated the effect of TOMATIS treatment for ASD-related deficits, including perceptual-motor, attentional, social, and emotional issues.

Discussion

ASD's auditory hypersensitivity hampers social information processing, but TOMATIS enhances cochlear frequency selectivity, aiding in capturing relevant auditory stimuli. In addition, the longitudinal study confirmed these findings, which proved TOMATIS training effective in clinically treating ASD. This study focused on audiometric indicators and behavioural improvement, elucidating the mechanisms behind the training's success. Behavioral improvements might stem from TOMATIS' frequency selectivity, reshaping auditory organ-cortical feedback loops to filter interference and focus on valid information.

Resting-state functional connectivity in an auditory network differs between aspiring professional and amateur musicians and correlates with performance

Auditory experience-dependent plasticity is often studied in the domain of musical expertise. Available evidence suggests that years of musical practice are associated with structural and functional changes in auditory cortex and related brain regions. Resting-state functional magnetic resonance imaging (MRI) can be used to investigate neural correlates of musical training and expertise beyond specific task influences. Here, we compared two groups of musicians with varying expertise: 24 aspiring professional musicians preparing for their entrance exam at Universities of Arts versus 17 amateur musicians without any such aspirations but who also performed music on a regular basis. We used an interval recognition task to define task-relevant brain regions and computed functional connectivity and graph-theoretical measures in this network on separately acquired resting-state data. Aspiring professionals performed significantly better on all behavioral indicators including interval recognition and also showed significantly greater network strength and global efficiency than amateur musicians. Critically, both average network strength and global efficiency were correlated with interval recognition task performance assessed in the scanner, and with an additional measure of interval identification ability. These findings demonstrate that task-informed resting-state fMRI can capture connectivity differences that correspond to expertise-related differences in behavior.

Revealing the differences of the representations of sounds from different directions in the human brain using functional connectivity

Many studies have focused on the processing mechanism of sound directions in the human brain, however, as far as we know, it remains unclear whether the representations of sounds from different directions are different. In the present study, 28 subjects were scanned while listening to sounds from different directions. We used the whole-brain functional connectivity (FC) analysis to explore which brain regions had significant changes. Our results revealed that sounds from different directions affected the FC in the widely distributed regions. Importantly, all regions showed significant differences in FC between the central and eccentric directions, while few regions showed a difference between the left and right directions. These findings revealed the differences in the representations of sounds from different directions.

Can theta burst stimulation safely influence auditory hearing thresholds in healthy young adults?

OBJECTIVE

This TBS sham-controlled study aimed to evaluate the effects of intermittent TBS (iTBS) and continuous TBS (cTBS) upon ipsilateral hearing thresholds after stimulation on the left auditory cortex.

METHODS

Sixty healthy adults, aged between 19 and 32 years (median of 23 years), were randomly distributed into three groups and underwent iTBS, cTBS or sham stimulation. Each double-blind experimental session comprised two pure tone audiometric evaluations per subject, before and after stimulation. To assess volunteer safety, a follow-up of at least 48 hours was implemented.

RESULTS

The iTBS group mean thresholds displayed a tendency to decrease after stimulation, predominantly in the 500 Hz-6000 Hz interval and group comparisons revealed significant differences between the iTBS and sham groups for 500 Hz (p = 0.041) and between the iTBS and cTBS groups for 4000 Hz (p = 0.038). Neither relevant side effects nor any significant hearing threshold impairment after active or sham stimulation were found.

CONCLUSIONS

A single stimulation session led to an effective neuromodulation of the auditory cortex, reflected in lower thresholds when using iTBS.

SIGNIFICANCE

These encouraging results with this safe noninvasive tool suggest that iTBS may have the potential to positively influence hearing thresholds.

Functional connectivity corresponding to the tonotopic differentiation of the human auditory cortex

Recent research has demonstrated that resting-state functional connectivity (RS-FC) within the human auditory cortex (HAC) is frequency-selective, but whether RS-FC between the HAC and other brain areas is differentiated by frequency remains unclear. Three types of data were collected in this study, including resting-state functional magnetic resonance imaging (fMRI) data, task-based fMRI data using six pure tone stimuli (200, 400, 800, 1,600, 3,200, and 6,400 Hz), and structural imaging data. We first used task-based fMRI to identify frequency-selective cortical regions in the HAC. Six regions of interest (ROIs) were defined based on the responses of 50 participants to the six pure tone stimuli. Then, these ROIs were used as seeds to determine RS-FC between the HAC and other brain regions. The results showed that there was RS-FC between the HAC and brain regions that included the superior temporal gyrus, dorsolateral prefrontal cortex (DL-PFC), parietal cortex, occipital lobe, and subcortical structures. Importantly, significant differences in FC were observed among most of the brain regions that showed RS-FC with the HAC. Specifically, there was stronger RS-FC between (1) low-frequency (200 and 400 Hz) regions and brain regions including the premotor cortex, somatosensory/-association cortex, and DL-PFC; (2) intermediate-frequency (800 and 1,600 Hz) regions and brain regions including the anterior/posterior superior temporal sulcus, supramarginal gyrus, and inferior frontal cortex; (3) intermediate/low-frequency regions and vision-related regions; (4) high-frequency (3,200 and 6,400 Hz) regions and the anterior cingulate cortex or left DL-PFC. These findings demonstrate that RS-FC between the HAC and other brain areas is frequency selective.