Issue Archive

Origins of P_(2a) and P_(2b) of auditory brainstem responses in the cat

Kang Jian, Wei Baoling

Audiological Laboratory of China Medical University

Abstract

Procaine or kainic acid was microinjected into the cochlear nucleus (CN) and superior olivary complexus (SOC) in 33 cats. Origins of P_(2a) and P_(2b) were investigated through observing effects of these agents on auditory brainstem responses (ABR). Incidence of the appearance of P_(2a) in cats was related to site of the reference electrode. It was 90% in vertex-vs-neck lead, but only 18% in vertex-vsmastoid lead. After injection of procaine into CN, only P_(1) remained in the ipsilateral ABR while the contralateral ABR did not change. After injection of kainic acid into CN, both P_(1) andP_(2a) remained but the amplitude of P_(2a) is increased. P_(3), P_(4) and P_(5) disappeared after bilateral injection of procaine into SOC. These results suggest that P_(2a) is generated mainly from the axon terminals of the primary auditory afferent neurons in the vicinity of CN, and is somewhat modified by a negative potential generated from the second auditory afferent neurons below SOC. Contralateral brainstem structures have no contribution to P_(2a) and P_(2b) in the cat.

Key words: Auditory brainstem response;Origin of potential;Procaine effect;Kainic acid effect

Received: 　　Accepted:

Corresponding author: 　　E-mail:

Citing This Article：

Kang Jian, Wei Baoling. Origins of P_(2a) and P_(2b) of auditory brainstem responses in the cat. Acta Physiol Sin 1986; 38 (3): (in Chinese with English abstract).