Neural body maps in human infants: Somatotopic responses to tactile stimulation in 7-month-olds

A large literature has examined somatotopic representations of the body in the adult brain, but little attention has been paid to the development of somatotopic neural organization in human infants. In the present study we examined whether the somatosensory evoked potential (SEP) elicited by brief tactile stimulation of infants' hands and feet shows a somatotopic response pattern at 7 months postnatal age. The tactile stimuli elicited a prominent positive component in the SEP at central sites that peaked around 175 ms after stimulus onset. Consistent with a somatotopic response pattern, the amplitude of the response to hand stimulation was greater at lateral central electrodes (C3 and C4) than at the midline central electrode (Cz). As expected, the opposite pattern was obtained to foot stimulation, with greater peak amplitude at Cz than at C3 and C4. These results provide evidence of somatotopy in human infants and suggest that the developing body map can be delineated using readily available methods such as EEG. These findings open up possibilities for further work investigating the organization and plasticity of infant body maps.