Auditory cortex in deaf brains gets recruited by visual stimuli, harming later implant success.

Evidence

Lee et al. ( 2003 ) used positron emission tomography (PET) to compare resting-state activity in 9 profoundly deaf individuals and 9 age-matched normal-hearing controls. They found that glucose metabolism in some auditory areas was lower than in normally-hearing people, but significantly increased with duration of deafness, and concluded that plasticity occurs in the sensory-deprived mature brain. Later, they showed that children with good speech understanding 3 years after implantation had enhanced metabolic activity in the left prefrontal cortex and decreased metabolic activity in right Heschl’s gyrus and in the posterior superior temporal sulcus before implantation compared to those with poor speech understanding (Lee et al. 2007 ). They argued that increased activity in the resting state in auditory areas may reflect cross modal plasticity that is detrimental to later success with the cochlear implant (CI). Recently, Dewey and Hartley ( 2015 ) used functional near infrared spectroscopy (fNIRS) to demonstrate that the auditory cortex of deaf individuals is abnormally activated by simple visual stimuli. — Dijk, Pim van, Physiology, Psychoacoustics and…, 4277

Categorization

• XREF: Cross-modal plasticity echoes the ‘use it or lose it’ deprivation-competition ideas in visual cortex research (e.g., congenital blindness recruiting visual cortex).
• QUESTION: Does resting-state auditory area hyperactivity in pre-implant deaf children correlate with implant outcomes in a way that could guide early intervention?