The study included 44 infants and toddlers, 23 of whom had hearing impairment and underwent auditory exams and fMRIs prior to implantation, and 29 of whom had normal hearing and participated as a control group. The children ranged in age from eight to 67 months.
Prior to implantation, the investigators tested two types of auditory stimuli (natural language speech and narrow-band noise tones) designed to stimulate blood flow and related activity in different areas of the brain. Two years after implantation, language performance was measured in the children who underwent implantation.
Using the pre-surgical tests, the study found elevated activity in two regions of the brain—one in the left hemisphere of the brain in areas (superior and middle temporal gyri) associated with speech recognition and language, and the other in the right cerebellar structures of the brain—that predict which children will benefit the most from cochlear implants and therefore indicate potential as biomarkers.