Auditory discrimination training rescues developmentally degraded directional selectivity and restores mature expression of GABA(A) and AMPA receptor subunits in rat auditory cortex.
Auditory frequency discrimination training can remediate deteriorated frequency representations and temporal information processing in the adult primary auditory cortex induced by early post-natal pulsed noise exposure. In this study, we investigated the neural mechanisms underlying the restoration of directional selectivity by auditory spatial discrimination training. Rats exposed to pulsed noise during a post-natal critical period demonstrated reduced auditory directional selectivity but could be successfully trained to identify a target sound stimulus at a specific azimuth angle using a reward-contingent auditory discrimination task (EXP rats). In contrast, rats passively exposed to the training procedure but no reward for correct identification of the azimuth angle (PNR rats) showed no improvement and behavioral performance remained significantly below EXP rats and control (CON) rats reared under a normal sonic environment. The expression levels of GABA(A) receptor subunits α1, α3, β2, and β3, and the AMPA GluR2 subunit were significantly altered in the auditory cortex of untrained noise-raised (NR and PNR) rats compared to age-matched CON rats, while trained noise-raised (EXP) rats exhibited levels of expression not significantly different from CON rats. Thus, reward-contingent sound-azimuth discrimination training may remediate directional selectivity by restoring the proper expression profile of neurotransmitter receptor subunits in the auditory cortex, allowing for normal spatial selectivity by cortical neurons. The development of auditory directional selectivity depends on the regulated expression of these excitatory and inhibitory neurotransmitter receptor subunits; early pulsed noise may disrupt the normal development of directional selectivity by interfering with receptor expression.
School of Life Science, Key Laboratory of Brain Functional Genomics, Ministry of Education, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062, China.
Fei
F
Guo
Jiping
J
Zhang
Xiaoqing
X
Zhu
Rui
R
Cai
Xiaoming
X
Zhou
Xinde
X
Sun
D000161:Acoustic Stimulation / Q000379:methods; D000818:Animals; D001303:Auditory Cortex / Q000378:metabolism* / Q000502:physiology*; D001307:Auditory Perception / Q000502:physiology*; D003423:Critical Period, Psychological; D004193:Discrimination Learning / Q000502:physiology*; D005260:Female; D006317:Hearing Loss, Noise-Induced / Q000378:metabolism* / Q000503:physiopathology*; D008297:Male; D021122:Protein Subunits / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000096:biosynthesis*; D011963:Receptors, GABA-A / Q000096:biosynthesis*; D020127:Recovery of Function / Q000502:physiology; D012201:Reward; D013017:Sound Localization / Q000502:physiology
D021122:Protein Subunits; D018091:Receptors, AMPA; D011963:Receptors, GABA-A