TY - JOUR

T1 - Cortical responses to promontorial stimulation in postlingual deafness

AU - Mortensen, Malene Vejby

AU - Madsen, Stig

AU - Gjedde, Albert

PY - 2005

Y1 - 2005

N2 - Electrical stimulation with a transtympanic electrode on the promontory of the middle ear allows the tasks of gap detection and temporal difference limen (TDL) to be carried out by both normally hearing and deaf subjects. Previous neuroimaging of normally hearing subjects revealed a region in the right posterior temporal lobe that is crucial to duration discrimination. The present study tested the hypothesis that postlingually deaf subjects recruit this area when they make subtle temporal discriminations. Fourteen postlingually deaf adult cochlear implant candidates were stimulated in the ear chosen for implantation. Altered cerebral activity was recorded with positron emission tomography as incremental 15-O-labelled water uptake. On stimulation with tone bursts, we found bilateral activity close to the primary auditory cortex in all subjects. However, subjects performing well on the TDL task demonstrated right-lateralized fronto-temporal and left-lateralized temporal activity in the respective TDL and gap-detection tasks, while subjects who failed to detect duration differences of less than 200 ms in the TDL discrimination task only had frontal and occipital rather than temporal lobe activation. We conclude that the ability to involve the right posterior temporal region is important to duration discrimination. This ability can be evaluated pre-operatively.

AB - Electrical stimulation with a transtympanic electrode on the promontory of the middle ear allows the tasks of gap detection and temporal difference limen (TDL) to be carried out by both normally hearing and deaf subjects. Previous neuroimaging of normally hearing subjects revealed a region in the right posterior temporal lobe that is crucial to duration discrimination. The present study tested the hypothesis that postlingually deaf subjects recruit this area when they make subtle temporal discriminations. Fourteen postlingually deaf adult cochlear implant candidates were stimulated in the ear chosen for implantation. Altered cerebral activity was recorded with positron emission tomography as incremental 15-O-labelled water uptake. On stimulation with tone bursts, we found bilateral activity close to the primary auditory cortex in all subjects. However, subjects performing well on the TDL task demonstrated right-lateralized fronto-temporal and left-lateralized temporal activity in the respective TDL and gap-detection tasks, while subjects who failed to detect duration differences of less than 200 ms in the TDL discrimination task only had frontal and occipital rather than temporal lobe activation. We conclude that the ability to involve the right posterior temporal region is important to duration discrimination. This ability can be evaluated pre-operatively.

U2 - 10.1016/j.heares.2005.05.011

DO - 10.1016/j.heares.2005.05.011

M3 - Journal article

C2 - 16098697

VL - 209

SP - 32

EP - 41

JO - Hearing Research

JF - Hearing Research

SN - 0378-5955

IS - 1-2

ER -