This is an older article, but it came up on my search and may be of some use going forward.
Zhongguo Zhong Xi Yi Jie He Za Zhi. 2012 Oct;32(10):1403-6.
[Nonlinear dynamic analysis of electrical signals of wide dynamic range neurons in the spinal dorsal horn evoked by acupuncture manipulation at different frequencies].
[Article in Chinese]

Abstract

OBJECTIVE:

To study the encoding information of electrical signals of wide dynamic range (WDR) neurons in the spinal dorsal horn evoked by acupuncture manipulation at different frequencies using nonlinear dynamics analysis.

METHODS:

Microelectrode extracellular recordings were used to observe the WDR neuron discharge evoked by acupuncture manipulation at Zusanli point (ST36) with different frequencies (0.5, 1, 2, and 3 Hz) in SD rats. The nonlinear dynamics analysis method was used to extract the nonlinear characteristic parameters, such as interspike interval, the Lyapunov exponent, Lempel-Ziv complexity, and the neural coding of the electrical signal evoked by acupuncture manipulations at different frequencies.

RESULTS:

Different characteristics were manifested with acupuncture manipulations at 4 different frequencies. More than a simple linear correlation was shown between the firing rate of the WDR neurons and the frequency of the acupuncture manipulation. The electrical signals evoked by acupuncture manipulation at Zusanli point (ST36) showed distinguished chaotic features.

CONCLUSIONS:

It is applicable and feasible to describe and summarize the rhythm of the acupuncture electrical signal using the concepts and terminology of the nonlinear dynamics. Different acupuncture manipulation methods could interfere the transmission, coding, and processing of electrical signals in the spinal dorsal horn.