Development of Human Somatosensory Cortical Functions – What have We Learned from Magnetoencephalography: A Review

Abstract

The mysteries of early development of cortical processing in humans have started to unravel with the help of new non-invasive brain research tools like multichannel magnetoencephalography (MEG). In this review, we evaluate, within a wider neuroscientific and clinical context, the value of MEG in studying normal and disturbed functional development of the human somatosensory system. The combination of excellent temporal resolution and good localization accuracy provided by MEG has, in the case of somatosensory studies, enabled the differentiation of activation patterns from the newborn’s primary (SI) and secondary somatosensory (SII) areas. Furthermore, MEG has shown that the functioning of both SI and SII in newborns has particular immature features in comparison with adults. In extremely preterm infants, the neonatal MEG response from SII also seems to potentially predict developmental outcome: those lacking SII responses at term show worse motor performance at age 2 years than those with normal SII responses at term. In older children with unilateral early brain lesions, bilateral alterations in somatosensory cortical activation detected in MEG imply that the impact of a localized insult may have an unexpectedly wide effect on cortical somatosensory networks. The achievements over the last decade show that MEG provides a unique approach for studying the development of the somatosensory system and its disturbances in childhood. MEG well complements other neuroimaging methods in studies of cortical processes in the developing brain.

Measuring Change in Somatosensation Across the Lifespan

“…Young children (3-4 yr) had the most varied and least accurate performance across all measures, which likely reflects expected developmental trajectories (Hane et al, 2010;Nevalainen et al, 2014). Testing demands are likely to have affected results.…”

“…Somatosensory function in particular (part of the "sensory" function of the NIH Toolbox) is important for studies of development and aging because sensation affects daily life function, relationships, and health outcomes (Hane, Henderson, Reeb-Sutherland, & Fox, 2010;Hirabayashi & Iwasaki, 1995;Nevalainen, Lauronen, & Pihko, 2014;Parush, Sohmer, Steinberg, & Kaitz, 2007). Somatosensory function refers to the detection, discrimination, and recognition of touch sensation and proprioception.…”

“…Somatosensory processing also enables people to experience pleasure and satisfaction (Hill, Fisher, Schmid, Crabtree, & Page, 2014), learn and adapt (Hane et al, 2010;Nevalainen et al, 2014), process the touch experiences of others (Keysers et al, 2010), and take action (Dijkerman & de Haan, 2007). Hill et al (2014) reported on the importance of touch sensation to performance of valued activities after stroke, highlighting the relationship between somatosensation and quality of life.…”

Body maps in the infant brain

“…In two EEG studies of preterm newborns, tactile stimulation of the hands was associated with visibly increased oscillatory activity at lateral central electrodes, while stimulation of the feet was associated with increased activity at the midline central electrode [42, 43]. The stimuli used in these studies were relatively uncontrolled in terms of their precise location, intensity, and duration, and the unusual profile of the preterm EEG signal [44] precludes comparisons with the brain responses of older children and adults.…”

Neuromagnetic Cortical Activation during Initiation of Optokinetic Nystagmus: An MEG Pilot Study

“…MEG outweighs EEG's ability to localize neuronal activity and resolve events with a higher temporal precision than fMRI. In addition, anatomical localization by MEG is acceptable even when compared with fMRI [Kandori et al, 2003;Stoeckel et al, 2007;Ilg, 2008;Nevalainen et al, 2014].…”