Publications [#70610] of Ruey-Kuang Cheng

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1. *Cheng, R.K., Manuelli, B., MacDonald, C.J., & Meck, W.H. (November 6, 2007). Oscillations of local field potentials in the dorsal striatum during interval timing reveal the encoding/decoding of temporal memory. (Poster presentation given at the 37th annual meeting of the Society for Neuroscience, San Diego, CA.).
   (last updated on 2008/06/18)

   Abstract:
   Recent evidence has shown that the dorsal striatum (DS) and frontal cortices are both involved in timing and time perception in the seconds-to-minutes range. These findings lead to the hypothesis that frontal-striatal circuits are able to code temporal information as a function of striatal median spiny neurons (MSN) receiving thousands of cortical inputs in an oscillatory pattern. Hence, the MSNs can monitor the temporal dynamics of cortical activity and the interactions between both regions yield a “time stamp” for event durations. In order to further elucidate the properties of this timing circuit, the current study investigated the oscillatory patterns in the DS by recording local field potentials (LFPs) in awake behaving animals. Sprague-Dawley male rats (6 mo) were first trained to press a lever and then underwent surgery for the implantation of a stainless-steel wire array in the right DS (A:+ 1.2 mm, L:+2.5 mm, and V:-4.0 mm to Bregma). Following recovery, LFPs were recorded while the rats received 10 daily sessions of discrete-trials fixed-interval (FI) 20-s training with the availability of food reinforcement signaled by a light stimulus. Rats then received an additional 12 sessions of peak-interval (PI) 20-s training during which a random half of the trials were unreinforced probe trials and the light signal remained on for a minimum of 60 s. Analysis of the lever pressing and LFP data indicated that early in FI training, during which lever pressing showed no temporal gradient, the power ratio of delta oscillations (1-4 Hz) in the DS increased at signal onset. This delta increase remained constant during the trial until food delivery, an event that reliably increased the ratio of high-gamma oscillations (100-200 Hz). Interestingly, as the rats gradually acquired temporal control of lever pressing, the major change in frequency-band ratios was that the high-gamma oscillations sharpened and shifted closer to the time of reinforcement (e.g., leftward). Moreover, during the PI probe trials a decrease in the delta ratio accompanied by an increase in high gamma occurred around the time of reinforcement (e.g., 20 s) - even though no food was delivered. In sum, the current data suggest that delta oscillations in the DS reflect the ongoing activation of a timing mechanism and that high-gamma oscillations reflect the encoding-decoding of the patterns of cortical-striatal activity stored in temporal memory.