Developmental and cross-modal plasticity in deafness: Evidence from the P1 and N1 event related potentials in cochlear implanted children

Abstract

Cortical development is dependent on extrinsic stimulation. As such, sensory deprivation, as in congenital deafness, can dramatically alter functional connectivity and growth in the auditory system. Cochlear implants ameliorate deprivation-induced delays in maturation by directly stimulating the central nervous system, and thereby restoring auditory input. The scenario in which hearing is lost due to deafness and then reestablished via a cochlear implant provides a window into the development of the central auditory system. Converging evidence from electrophysiologic and brain imaging studies of deaf animals and children fitted with cochlear implants has allowed us to elucidate the details of the time course for auditory cortical maturation under conditions of deprivation. Here, we review how the P1 cortical auditory evoked potential (CAEP) provides useful insight into sensitive period cut-offs for development of the primary auditory cortex in deaf children fitted with cochlear implants. Additionally, we present new data on similar sensitive period dynamics in higher-order auditory cortices, as measured by the N1 CAEP in cochlear implant recipients. Furthermore, cortical re-organization, secondary to sensory deprivation, may take the form of compensatory cross-modal plasticity. We provide new case-study evidence that cross-modal re-organization, in which intact sensory modalities (i.e., vision and somatosensation) recruit cortical regions associated with deficient sensory modalities (i.e., auditory) in cochlear implanted children may influence their behavioral outcomes with the implant. Improvements in our understanding of developmental neuroplasticity in the auditory system should lead to harnessing central auditory plasticity for superior clinical technique.

Maturação dos potenciais evocados auditivos de longa latência em crianças ouvintes: análise do complexo P1-N1-P2-N2

“…Intrinsic factors are related amongst other things to the susceptibility of the individual and to abilities for learning, such as cognitive functions for attention and memory. On the other hand, extrinsic factors are related to the exposure of the individual to the environment (1,26) . Such variables are capable of providing different development rhythms, and therefore, of leading to differences in the time of emergence for each component of the complex P1-N1-P2-N2.…”

“…After nine months of stimulation, a reduction of latency values of component P1 in younger children (G1) was observed, as well as for component N2 in older children (G2). It is known that myelination as well as maturation of the auditory nervous fibers, mainly occurs in peripheral regions and gradually extends to the more central regions of the auditory system (26) . This process is possibly responsible for the reduction in latency values for LLAEP components (15,27) .…”

Modularity in complex multilayer networks with multiple aspects: a static perspective

“…For instance, suppose we have a multilayer electroencephalogram network in which each person is treated as a layer. Apparently, the age difference and gender of the patients will greatly influence the result (Sharma et al 2015;Repovs et al 2011). Therefore, we should enable the proposed model to handle such networks with unevenly distributed layers.…”

Impact of hearing aid use on auditory perception and verbal short-term memory in children with bimodal stimulation

“…After that age there is a high likelihood of de-coupling of the primary auditory cortical areas wich are likely to be de-coupled from surrounding higher-order cortex (Kral & Sharma, 2012). Secondary to sensory deprivation, cross-modal reorganization of auditory cortex happens, in which intact sensory modalities (such as vision and somatosensation) recruit cortical regions associated with deficient sensory modalities (i.e., auditory) (Sharma, Campbell & Cardon, 2014). Lateimplanted subjects can detect the auditory stimulus, but the majority cannot discriminate complex sounds appropriately, resulting in compromised speech understanding and oral language learning.…”