TMS Modulation of Sensory-Evoked Neural Activity in Autistic Adults with Sensory Over-Responsivity
Poster No:
107
Submission Type:
Abstract Submission
Authors:
Amy Than1, Melis Cakar1, Akila Kadambi1, Elizabeth Matsiyevskiy1, Sapna Ramappa2, Megan Banchik1, Apurva Chaturvedi1, Urvi Shah1, Emily Wood1, Mirella Dapretto1, Marco Iacoboni1, Shulamite Green1
Institutions:
1University of California, Los Angeles, Los Angeles, CA, 2University of California, San Francisco, San Francisco, CA
First Author:
Co-Author(s):
Introduction:
Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder marked by challenges with social communication, language, and repetitive behaviors as well as sensory processing. Of the sensory symptoms in ASD, sensory over-responsivity (SOR) is highly impairing and affects 50-70% of autistic individuals (Baranek et al., 2006). SOR is characterized by an aversive response to ordinary sensory stimuli and dysregulation in brain regions such as the prefrontal and sensory cortices (Schwarzlose et al., 2023; Green et al., 2017). To date, there are no pharmacological or behavioral treatments for SOR. While repetitive transcranial magnetic stimulation (rTMS) has been a promising treatment for core symptoms of ASD such as repetitive and stereotyped behaviors as well as social impairments (Barahona et.al., 2018; Gomez et.al., 2017), its effect on symptoms within the sensory domain remains unclear. This study utilized functional magnetic resonance imaging (fMRI) to investigate the effects of intermittent theta-burst stimulation (iTBS) to the left dorsolateral prefrontal cortex (dlPFC) on sensory processing in adults with ASD and SOR.
Methods:
Participants were young adults, 18-24 years of age, with ASD and SOR (N=12). Task-based fMRI data were collected at two time points. The fMRI task consisted of 15-second blocks of mildly aversive tactile stimuli (scratchy cloth rubbed on participant's left arm) presented simultaneously with alternating auditory or visual stimuli, with 12.5 seconds of fixation between blocks. In the current analysis, we focused on the auditory plus tactile stimulation condition, as this joint condition has previously been shown to elicit the most atypical neural responses in autistic youth (e.g., Green et al., 2015, 2019). Six blocks of each condition were presented, for a total of 6.7 minutes. The order of stimulus conditions was counterbalanced among participants. Immediately before the second MRI session, intermittent Theta-Burst Stimulation (iTBS) was administered to the left dlPFC, which has been shown to produce NMDA receptor dependent long-lasting facilitatory effects on cortical excitability (Huang et al., 2007; Huang et al., 2005). A Figure 8, 700mm coil (Magstim Rapid2) was used with an intensity of 80% active motor threshold. A total of 600 pulses was delivered in 20 two-second on and 8-second off cycles. Statistical analyses were conducted using the general linear model (GLM) implemented in FSL.
Results:
During joint auditory and tactile stimulation, excitatory TMS administration elicited greater neural activity in occipital fusiform gyrus and inferior lateral occipital cortex compared to baseline (Figure 1, left). Additionally, excitatory TMS administration diminished neural activity in the postcentral gyrus/supramarginal gyrus/operculum (Figure 1, right), compared to baseline.
Conclusions:
Our results show that iTBS to the left dlPFC modulates atypical neural responses to mildly aversive stimuli in autistic adults with SOR. More specifically, iTBS to the left dlPFC downregulated neural responses in primary and higher-order somatosensory processing regions that have previously been shown to be hyperactive in individuals with ASD and SOR (Green et al. 2015, 2019). Results suggest that iTBS to the PFC, a region implicated in sensory regulation in ASD (e.g., Green et al., 2019), facilitated inhibition of sensory responses. Additionally iTBS to the left dlPFC elicited more activity in visual processing regions, indicating recruitment of task-irrelevant information possibly to disengage from aversive task-related sensory experiences. Future directions include replicating results with a larger sample. To the best of our knowledge, this is the first study to examine changes in MRI-based brain responses to aversive sensory stimuli following TMS over the dlPFC in adults with ASD. Our findings may inform future TMS intervention strategies for SOR in autistic individuals.
Brain Stimulation:
TMS 1
Disorders of the Nervous System:
Neurodevelopmental/ Early Life (eg. ADHD, autism) 2
Modeling and Analysis Methods:
Activation (eg. BOLD task-fMRI)
Keywords:
Autism
FUNCTIONAL MRI
MRI
Somatosensory
Transcranial Magnetic Stimulation (TMS)
1|2Indicates the priority used for review
Provide references using author date format
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Green, S.A. (2013), “Overreactive Brain Responses to Sensory Stimuli in Youth with Autism Spectrum Disorders.” Journal of the American Academy of Child and Adolescent Psychiatry 52(11): 1158–72
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