Long-Range Auditory Functional Connectivity in Hearing Loss and Rehabilitation

Background: Patients with age-related sensorineural hearing loss (HL) may benefit from auditory input amplification by using hearing aids (HAs). However, the impact of both HL- and HA-based rehabilitation on central auditory functional connectivity (FC) is not clear. Methodology: Sixty-two HL (22 females, aged 64.4 +/- 7.6 years, pure-tone average 50.9 +/- 14.7 dB right ear, 50.7 +/- 12.9 dB left ear) and 32 normal hearing (NH) subjects (22 females, aged 59.3 +/- 7.3 years) were examined in a 3T magnetic resonance imaging (MRI) study. HL patients were analyzed cross-sectionally at baseline (vs. NH subjects) and longitudinally at 6-month follow-up. Between the 2 scans, 31/62 patients used the HA 9.5 +/- 3.8 h a day. Arterial spin labeling and blood oxygen level-dependent resting-state functional MRI were performed to measure regional perfusion in the primary auditory cortex and, from here to the whole brain, seed-based FC was performed. Before each scan, HL patients underwent audiological and neurological assessments. Results: At baseline, the HL condition was associated with regional hypoperfusion in right Heschl's gyrus (seed) and negative seed-based FC (anticorrelation) in posterior brain regions. Long-range FC in the precuneus correlated negatively with pure-tone and speech reception average thresholds. At 6-month follow-up, HA usage was associated with seed-based FC increase in the right superior frontal gyrus (SFG) and seed-based FC reduction in the right middle temporal gyrus. Long-range FC changes in the SFG correlated positively with executive function improvements. Conclusions: These findings suggest that HA-based rehabilitation may not reverse HL-related neural effects and yet carry neurological benefits by retuning long-range FC of the auditory system.