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Background and Aim: Following an early visual deprivation, the neural network involved in processing auditory spatial information undergoes a profound reorganization. In order to investigate this process, event-related potentials provide accurate information about time course neural activation as well as perception and cognitive processes. In this study, the latency and amplitude of auditory P300 were compared in sighted and early blind individuals in age range of 18-25 years old.

Methods: In this cross-sectional study, auditory P300 potential was measured in conventional oddball paradigm by using two tone burst stimuli (1000 and 2000 Hz) on 40 sighted subjects and 19 early blind subjects with mean age 20.94 years old.

Results: The mean latency of P300 in early blind subjects was significantly smaller than sighted subjects (p=0.00.( There was no significant difference in amplitude between two groups (p>0.05).

Conclusion: Reduced latency of P300 in early blind subjects in comparison to sighted subjects probably indicates the rate of automatic processing and information categorization is faster in early blind subjects because of sensory compensation. It seems that neural plasticity increases the rate of auditory processing and attention in early blind subjects.

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Background and Aim: Studies have shown that long-term use of monaural hearing aid in symmetrical hearing losses may lead to physiological changes. In this research, the possibility of plasticity occurrence in bilaterally hearing impaired listeners fitted with only one hearing aid was investigated.

Methods: Our study was carried out on 12 elderly listeners with a mean age of 61.92 years who had symmetrical moderate to severe sensory neural hearing loss in both ears. All of the participants had minimum monaural hearing aid experience of 2 years. We used auditory brainstem response (ABR) testing in order to compare absolute latency and amplitude of wave V between the two ears of cases. Air conduction click stimuli were presented monaurally at 80, 90 and 100 dB nHL.

Results: Despite the shorter absolute latency of wave V in the fitted ear, no significant difference was found between the two ears (p>0.389). The difference between wave V amplitude of both ears was greater in 90 dB nHL level (p=0.043). Women showed shorter mean latency than men and the mean amplitude of women was greater than men. Significant gender difference was observed in absolute latency of wave V (p<0.037).

Conclusion: Our findings indicate that the use of monaural hearing aid in symmetrical hearing losses can induce neural plasticity within auditory brainstem pathways which can be displayed by auditory brainstem response test.