Eggermont J J
Department of Psychology, University of Calgary, Alberta, Canada.
Hear Res. 1991 Nov;56(1-2):153-67. doi: 10.1016/0378-5955(91)90165-6.
Periodicity coding was studied in primary auditory cortex of the ketamine anesthetized cat by simultaneously recording with two electrodes from up to 6 neural units in response to one second long click trains presented once per 3 s. Trains with click rates of 1, 2, 4, 8, 16 and 32/s were used and the responses of the single units were quantified by both rate measures (entrainment and rate modulation transfer function, rMTF) and synchronization measures (vector strength VS and temporal modulation transfer functions, tMTF). The rate measures resulted in low-pass functions of click rate and the synchrony measures resulted in band-pass functions of click rate. Limiting rates (-6 dB point of maximum response) were in the range of 3-24 Hz depending on the measure used. Best modulating frequencies were in the range of 5-8 Hz again depending on the synchrony measure used. It appeared that especially the VS was highly sensitive to spontaneous firing rate, duration of the post click suppression and the size of the rebound response after the suppression. These factors were dominantly responsible for the band-pass character of the VS-rate function and the peak VS frequency was nearly identical to the inverse of the suppression period. It is concluded that the use of the VS and to a lesser extent also the tMTF as the sole measure for the characterization of periodicity coding is not recommended in cases where there is a strong suppression of spontaneous activity. The combination of entrainment and tMTF appeared to characterize the periodicity coding in an unambiguous way.
在氯胺酮麻醉猫的初级听觉皮层中研究了周期性编码，通过两个电极同时记录多达6个神经单元对每3秒呈现一次的1秒长的滴答声序列的反应。使用了滴答声速率为1、2、4、8、16和32/秒的序列，单个单元的反应通过速率测量（夹带和速率调制传递函数，rMTF）和同步测量（向量强度VS和时间调制传递函数，tMTF）进行量化。速率测量产生了滴答声速率的低通函数，同步测量产生了滴答声速率的带通函数。根据所使用的测量方法，极限速率（最大反应的-6 dB点）在3-24 Hz范围内。最佳调制频率再次在5-8 Hz范围内，这同样取决于所使用的同步测量方法。似乎特别是VS对自发放电速率、滴答声后抑制的持续时间以及抑制后反弹反应的大小高度敏感。这些因素主要决定了VS-速率函数的带通特性，并且VS峰值频率几乎与抑制期的倒数相同。得出的结论是，在自发活动受到强烈抑制的情况下，不建议仅使用VS以及在较小程度上使用tMTF作为表征周期性编码的唯一测量方法。夹带和tMTF的组合似乎以明确的方式表征了周期性编码。
