Cortical responses to tactile stimuli in preterm infants

Abstract

The conventional assessment of preterm somatosensory functions using averaged cortical responses to electrical stimulation ignores the characteristic components of preterm somatosensory evoked responses (SERs). Our study aimed to systematically evaluate the occurrence and development of SERs after tactile stimulus in preterm infants. We analysed SERs performed during 45 electroencephalograms (EEGs) from 29 infants at the mean post‐menstrual age of 30.7 weeks. Altogether 2,087 SERs were identified visually at single‐trial level from unfiltered signals capturing also their slowest components. We observed salient SERs with a high‐amplitude slow component at a high success rate after hand (95%) and foot (83%) stimuli. There was a clear developmental change in both the slow wave and the higher‐frequency components of the SERs. Infants with intraventricular haemorrhage (IVH; eleven infants) had initially normal SERs, but those with bilateral IVH later showed a developmental decrease in the ipsilateral SER occurrence after 30 weeks of post‐menstrual age. Our study shows that tactile stimulus applied at bedside elicits salient SERs with a large slow component and an overriding fast oscillation, which are specific to the preterm period. Prior experimental research indicates that such SERs allow studying both subplate and cortical functions. Our present findings further suggest that they might offer a window to the emergence of neurodevelopmental sequelae after major structural brain lesions and, hence, an additional tool for both research and clinical neurophysiological evaluation of infants before term age.

Development of prefrontal cortex

“…In preterm birth, changes in white and gray matter including reductions in cortical surface area and cortical thickness of the PFC are described [ 361 – 364 ]. Disruptions in PFC network activity often further aggravates the already compromised neurocognitive development in these children [ 365 , 366 ].…”

Sensorimotor Integration in Childhood Dystonia and Dystonic Cerebral Palsy—A Developmental Perspective

“…Recent fMRI studies show a somatotopic organization of sensorimotor cortex even in preterm human infants (55), suggesting early intrinsic determination of a broad somatotopic map. This is supported by the topography of sensory evoked responses to tactile stimulation of the upper and lower limbs in preterms (56). However, the fine-tuning of somatotopic organization within sensory and motor cortices requires experience-dependent synaptic plasticity.…”

“…It can be envisaged that injury or dysfunction of the ascending sensory tracts of the posterior thalamic radiation will disrupt the passage of sensory information to the sensory cortex, and that the subsequent disruption of sensorimotor cortex neuronal oscillatory activity will in turn affect the development of sensorimotor circuits, even if the dysfunction of ascending pathways is only transient. Indeed, in preterm infants with structural brain lesions (bilateral intraventricular hemorrhage) somatosensory evoked responses to tactile stimuli are abnormal (56). Interestingly, the responses only became abnormal after a delay of several weeks (56), suggesting that the abnormality may reflect a neuroplastic response with re-organization of the relevant neuronal networks.…”

“…Indeed, in preterm infants with structural brain lesions (bilateral intraventricular hemorrhage) somatosensory evoked responses to tactile stimuli are abnormal (56). Interestingly, the responses only became abnormal after a delay of several weeks (56), suggesting that the abnormality may reflect a neuroplastic response with re-organization of the relevant neuronal networks.…”

The impact of premature extrauterine exposure on infants’ stimulus-evoked brain activity across multiple sensory systems

“…Brain activity evoked by sensory stimulation can be recorded using electroencephalography (EEG) to assess the functional integrity of these developing sensory systems. Somatosensory (Leikos et al, 2020;Majnemer and Rosenblatt, 1996;Vanhatalo et al, 2009), noxious (Hartley et al, 2017;Slater et al, 2010b), auditory (Ribeiro and Carvallo, 2008;Taylor et al, 1996), and visual (Majnemer and Rosenblatt, 1996;Taylor et al, 1992;Whyte, 1993) evoked potentials have all previously been independently identified in infants using a variety of analytical methods. However, to date, there is limited data assessing the impact of extrauterine exposure on the developmental trajectory of sensory evoked cortical activity across multiple stimulus modalities within the same infants.…”