Tactile cortical responses and association with tactile reactivity in young children on the autism spectrum

Abstract

Background Unusual behavioral reactions to sensory stimuli are frequently reported in individuals on the autism spectrum (AS). Despite the early emergence of sensory features (< age 3) and their potential impact on development and quality of life, little is known about the neural mechanisms underlying sensory reactivity in early childhood autism. Methods Here, we used electroencephalography (EEG) to investigate tactile cortical processing in young children aged 3–6 years with autism and in neurotypical (NT) children. Scalp EEG was recorded from 33 children with autism, including those with low cognitive and/or verbal abilities, and 45 age- and sex-matched NT children during passive tactile fingertip stimulation. We compared properties of early and later somatosensory-evoked potentials (SEPs) and their adaptation with repetitive stimulation between autistic and NT children and assessed whether these neural measures are linked to “real-world” parent-reported tactile reactivity. Results As expected, we found elevated tactile reactivity in children on the autism spectrum. Our findings indicated no differences in amplitude or latency of early and mid-latency somatosensory-evoked potentials (P50, N80, P100), nor adaptation between autistic and NT children. However, latency of later processing of tactile information (N140) was shorter in young children with autism compared to NT children, suggesting faster processing speed in young autistic children. Further, correlational analyses and exploratory analyses using tactile reactivity as a grouping variable found that enhanced early neural responses were associated with greater tactile reactivity in autism. Limitations The relatively small sample size and the inclusion of a broad range of autistic children (e.g., with low cognitive and/or verbal abilities) may have limited our power to detect subtle group differences and associations. Hence, replications are needed to verify these results. Conclusions Our findings suggest that electrophysiological somatosensory cortex processing measures may be indices of “real-world” tactile reactivity in early childhood autism. Together, these findings advance our understanding of the neurophysiological mechanisms underlying tactile reactivity in early childhood autism and, in the clinical context, may have therapeutic implications.

Autism interest intensity in early childhood associates with executive functioning but not reward sensitivity or anxiety symptoms

“…Exclusion criteria for the autism group included a known genetic etiology of autism or history of major head trauma including loss of consciousness for >5 min. Children participated in a separate study that included electroencephalography (EEG) described elsewhere ( Espenhahn et al, 2021 ) and were therefore also excluded if they experienced seizures. Co-occurring conditions in the autism group were reported by parents and included attention-deficit/hyperactivity disorder ( N = 5), global developmental delay ( N = 3), and global developmental delay coupled with pre-term birth, <28 weeks gestational age ( N = 1).…”

Tactile sensory processing as a precursor of executive attention: Toward early detection of attention impairments and neurodevelopmental disorders

“…We now need to address the mechanisms mediating the relationship between somatosensory processing and NDD, taking into account the variety of syndromes. EEG studies in ADHD show increased SEP amplitude (Parush et al, 2007), whereas in ASD they found decreased amplitude and shorter latency (Espenhahn et al, 2021).…”

“…Recently, Espenhahn et al (2021) found that the N140 response, a component of SEP, had a lower amplitude and shorter latency in children with ASD. As for ADHD, the authors propose that an imbalance between excitation and inhibition in the brain underlies these observations.…”

Modulation of the thermosensory system by oxytocin

“…Moreover, patients with ASD have an aversion to touch, suggesting that a tactile stimulus, albeit weak, is a source of discomfort indicating a potential hypersensitivity to this type of stimulus (Moore, 2015 ; Kaiser et al, 2016 ). This tactile atypia could be explained by an excitation/inhibition imbalance at the level of somatosensory neurons of the DRG (Lipina and Blundell, 2022 ), modification of somatosensation and somatotopic map (Espenhahn et al, 2021 ), or even direct alteration of the somatosensory circuit in patients with ASD (Orefice, 2020 ).…”