Cortical activations in sequential bilateral cochlear implant users

Abstract

This study aimed to examine auditory and visual cortical activations in bilateral cochlear implant recipients using [(18)F]-FDG positron emission tomography. We aimed to compare the activations from use of the first implant alone, the second implant alone, and both implants together. When both implants were activated simultaneously, summation of cortical activity did not occur. The first and second implants demonstrated evidence of developing distinct neural networks. The first implants show stronger bilateral recruitment of the auditory areas than the second implants. Visual cortical activations occur in response to stimulation of the second but not the first implants. When both implants were activated together, there were no visual activations suggesting interaction between the first- and second-implant networks. These findings add to the existing knowledge of plasticity following cochlear implantation and demonstrate a variability of these processes that was previously unreported.

Combined Brain-Perfusion SPECT and EEG Measurements Suggest Distinct Strategies for Speech Comprehension in CI Users With Higher and Lower Performance

“…Similarly, previous fMRI studies with NH listeners have reported that monaural presentation of speech results in a stronger contralateral activation of the primary auditory cortex (Jäncke et al, 2002;Stefanatos et al, 2008). Contralaterally predominant activation has also been observed with unilateral as opposed to bilateral stimulation in CI users (Green et al, 2011;Coez et al, 2014).…”

Changes in children's speech discrimination and spatial release from masking between 2 and 4 years after sequential cochlear implantation

“…As a result, sequentially-implanted children may experience prolonged and asymmetrical auditory deprivation compared to normally-hearing children, children who use bilateral hearing aids and children who undergo simultaneous cochlear implantation. As a consequence, the development of binaural listening skills for sequentially-implanted children is more likely to be limited by changes in plasticity in the maturing auditory system (Sharma et al, 2007;Green et al, 2011;Gordon et al, 2013;Sparreboom, 2013).…”

Potential benefits from cochlear implantation of children with unilateral hearing loss

“…Supporting evidence of these changes is also available from functional imaging studies. Green et al (2011), for example, reported visual cortex activation produced by the second device in sequential CI recipients, but not the first, as indicated by positron emission tomography. Tibbetts et al (2011) used functional MRI (fMRI) to compare cortical connectivity in children with UHL with that of their NH siblings.…”