Cortical reponses to electrical stimulation from cochlear implants

In order to examine factors contributing to speech perception performance variations in cochlear implant users, single photon emission computed tomography (SPECT) was used to examine cortical activity elicited by the electrical stimulation of multichannel cochlear implants. Subjects watched a 15‐min videotaped story under several conditions: (a) audio presented monaurally in the aided right or left ears; (b) audio presented binaurally with aids; (c) a visual‐only presentation; and (d) signals processed through the implant. Five minutes after the start of each story, 99mTc HMPAO was injected over 30 s to insure subjects were unaware of the tracer administration. Right and left monaural stimulation in normal‐hearing subjects resulted in significant bilateral activation of Brodmann areas 41, 42, 22, 21, and 38. Despite similar hearing losses to each ear, significant differences in per‐operative auditory cortex activation was observed between ears across the subjects. Post‐implant, individuals with relatively...