1 Department of Psychology, Concordia University, Montreal, Quebec, Canada, H4B 1R6.
2 Hearts for Hearing Foundation, Oklahoma City, OK 73120, USA.
3 Department of Otolaryngology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
4 Department of Audiology & Speech-Language Pathology, University of North Texas, Denton, TX 76201, USA.
5 Department of Developmental and Social Psychology, University of Padova, 35131 Padua, Italy.
6 Section of Neural Engineering with Signal Analytics and Artificial Intelligence, Department of Neurology, University Hospital Würzburg, 97080 Würzburg, Germany.
7 Haskins Laboratories, New Haven, CT 06511, USA.

Over the first years of life, the brain undergoes substantial organization in response to environmental stimulation. In a silent world, it may promote vision by (i) recruiting resources from the auditory cortex and (ii) making the visual cortex more efficient. It is unclear when such changes occur and how adaptive they are, questions that children with cochlear implants can help address. Here, we examined 7-18 years old children: 50 had cochlear implants, with delayed or age-appropriate language abilities, and 25 had typical hearing and language. High-density electroencephalography and functional near-infrared spectroscopy were used to evaluate cortical responses to a low-level visual task. Evidence for a 'weaker visual cortex response' and 'less synchronized or less inhibitory activity of auditory association areas' in the implanted children with language delays suggests that cross-modal reorganization can be maladaptive and does not necessarily strengthen the dominant visual sense.