Following implantation of a cochlear prosthetic, auditory cortex exhibits a remarkable plasticity in its ability to establish auditory signal processing after a period of deprivation. Our long-term goal is to understand and define the capabilities of non-primary auditory cortex to establish auditory function following cochlear implant. This endeavor requires the elucidation of the essential contributions that non-primary auditory cortex makes to fundamental aurally-guided behaviors in the intact (hearing) condition, as well as an assessment of the behavioral capabilities of non-primary auditory cortex following cochlear implant in congenitally deaf subjects. The first specific aim of this application is to determine that non-primary auditory cortex contains specialized regions for the processing of pattern perception and spatial localization. In intact cats, we will examine the contributions that the anterior and posterior auditory fields (AAF and PAF, respectively) make to pattern recognition and the perception of auditory space. Each area will be reversibly deactivated with cooling and we expect to be able to doubly-dissociate pattern discrimination and spatial localization functions to AAF and PAF cortices, respectively.
The second aim i n the study is to determine if congenitally deaf (CD) cats with cochlear prosthetics implanted early in development (2 months of age) can establish aurally-mediated behaviors. We will test if the animals are able to attain high performance levels on the auditory discrimination, detection, and localization tasks examined in Aim 1. The results of the first two aims are brought together in Aim 3, where we will combine the CD cats with cochlear implants examined in Aim 2 with the reversible deactivation techniques used in Aim 1 to determine if the characteristic normal functional cartography of non-primary auditory cortex is established following early cochlear implantation. To accomplish this, we will reversibly deactivate AAF and PAF cortices in the CD cats with cochlear implants while performing the battery of auditory tasks described above, and compare the results with those from the intact cats in Aim 1. The results from these studies will be directly applicable to clinical situations concerning the functional outcomes of cochlear implants in young children. ? ?
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| Kral, Andrej; Eggermont, Jos J (2007) What's to lose and what's to learn: development under auditory deprivation, cochlear implants and limits of cortical plasticity. Brain Res Rev 56:259-69 |
| Malhotra, Shveta; Hall, Amee J; Lomber, Stephen G (2004) Cortical control of sound localization in the cat: unilateral cooling deactivation of 19 cerebral areas. J Neurophysiol 92:1625-43 |
