Limits...
Modulation of Purkinje cell complex spike waveform by synchrony levels in the olivocerebellar system.

Lang EJ, Tang T, Suh CY, Xiao J, Kotsurovskyy Y, Blenkinsop TA, Marshall SP, Sugihara I - Front Syst Neurosci (2014)

Bottom Line: Control experiments showed that changes in variance with synchrony were primarily due to changes in the CS waveform, as opposed to changes in the strength of field potentials from surrounding cells.Direct counts of spikelets showed that their number increased with synchronization of CS activity.In sum, these results provide evidence of a causal link between two of the distinguishing characteristics of the olivocerebellar system, its ability to generate synchronous activity and the waveform of the CS.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroscience and Physiology, New York University School of Medicine New York, NY, USA.

ABSTRACT
Purkinje cells (PCs) generate complex spikes (CSs) when activated by the olivocerebellar system. Unlike most spikes, the CS waveform is highly variable, with the number, amplitude, and timing of the spikelets that comprise it varying with each occurrence. This variability suggests that CS waveform could be an important control parameter of olivocerebellar activity. The origin of this variation is not well known. Thus, we obtained extracellular recordings of CSs to investigate the possibility that the electrical coupling state of the inferior olive (IO) affects the CS waveform. Using multielectrode recordings from arrays of PCs we showed that the variance in the recording signal during the period when the spikelets occur is correlated with CS synchrony levels in local groups of PCs. The correlation was demonstrated under both ketamine and urethane, indicating that it is robust. Moreover, climbing fiber reflex evoked CSs showed an analogous positive correlation between spikelet-related variance and the number of cells that responded to a stimulus. Intra-IO injections of GABA-A receptor antagonists or the gap junction blocker carbenoxolone produced correlated changes in the variance and synchrony levels, indicating the presence of a causal relationship. Control experiments showed that changes in variance with synchrony were primarily due to changes in the CS waveform, as opposed to changes in the strength of field potentials from surrounding cells. Direct counts of spikelets showed that their number increased with synchronization of CS activity. In sum, these results provide evidence of a causal link between two of the distinguishing characteristics of the olivocerebellar system, its ability to generate synchronous activity and the waveform of the CS.

No MeSH data available.


Intra-IO injection of carbenoxolone reduces spikelet-related variance. (A1,B1) Schematics showing layout of multielectrode recording arrays from two experiments. In the second experiment (B1) the red circles represent PCs whose CSs became less synchronous after carbenoxolone and the black circles represent PCs whose CSs became more synchronous. (A2,B2) scatter plot of spikelet-related variance in control vs. carbenoxolone condition. (A3,B3) Scatter plot of percent change in synchrony vs. percent change in variance between control and carbenoxolone conditions. (C) Data from plots (A3,B3) combined.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4214199&req=5

Figure 7: Intra-IO injection of carbenoxolone reduces spikelet-related variance. (A1,B1) Schematics showing layout of multielectrode recording arrays from two experiments. In the second experiment (B1) the red circles represent PCs whose CSs became less synchronous after carbenoxolone and the black circles represent PCs whose CSs became more synchronous. (A2,B2) scatter plot of spikelet-related variance in control vs. carbenoxolone condition. (A3,B3) Scatter plot of percent change in synchrony vs. percent change in variance between control and carbenoxolone conditions. (C) Data from plots (A3,B3) combined.

Mentions: We next tested whether spikelet-related variance decreased when CS synchrony was reduced by injection of carbenoxolone, a gap junction blocker, into the IO in two experiments from a previous study (Blenkinsop and Lang, 2006). The recording arrays are shown in Figures 7A1,B1. Overall, the induced changes in synchrony and variance were highly correlated. In the first experiment the intra-IO injection produced a −72.5 ± 11.0% change in synchrony, with all PCs showing a reduction (n = 14 PCs; p = 6.4 × 10−5, paired t-test). Correspondingly, variance was reduced from control levels in every PC (−28.2 ± 12.7%; p = 1.5 × 10−5, paired t-test; Figure 7A2, all circles below y = x line). However, a scatterplot of the percent changes in synchrony and variance showed only a relatively weak correlation that was not significant (r = 0.37, p = 0.187; Figure 7A3).


Modulation of Purkinje cell complex spike waveform by synchrony levels in the olivocerebellar system.

Lang EJ, Tang T, Suh CY, Xiao J, Kotsurovskyy Y, Blenkinsop TA, Marshall SP, Sugihara I - Front Syst Neurosci (2014)

Intra-IO injection of carbenoxolone reduces spikelet-related variance. (A1,B1) Schematics showing layout of multielectrode recording arrays from two experiments. In the second experiment (B1) the red circles represent PCs whose CSs became less synchronous after carbenoxolone and the black circles represent PCs whose CSs became more synchronous. (A2,B2) scatter plot of spikelet-related variance in control vs. carbenoxolone condition. (A3,B3) Scatter plot of percent change in synchrony vs. percent change in variance between control and carbenoxolone conditions. (C) Data from plots (A3,B3) combined.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4214199&req=5

Figure 7: Intra-IO injection of carbenoxolone reduces spikelet-related variance. (A1,B1) Schematics showing layout of multielectrode recording arrays from two experiments. In the second experiment (B1) the red circles represent PCs whose CSs became less synchronous after carbenoxolone and the black circles represent PCs whose CSs became more synchronous. (A2,B2) scatter plot of spikelet-related variance in control vs. carbenoxolone condition. (A3,B3) Scatter plot of percent change in synchrony vs. percent change in variance between control and carbenoxolone conditions. (C) Data from plots (A3,B3) combined.
Mentions: We next tested whether spikelet-related variance decreased when CS synchrony was reduced by injection of carbenoxolone, a gap junction blocker, into the IO in two experiments from a previous study (Blenkinsop and Lang, 2006). The recording arrays are shown in Figures 7A1,B1. Overall, the induced changes in synchrony and variance were highly correlated. In the first experiment the intra-IO injection produced a −72.5 ± 11.0% change in synchrony, with all PCs showing a reduction (n = 14 PCs; p = 6.4 × 10−5, paired t-test). Correspondingly, variance was reduced from control levels in every PC (−28.2 ± 12.7%; p = 1.5 × 10−5, paired t-test; Figure 7A2, all circles below y = x line). However, a scatterplot of the percent changes in synchrony and variance showed only a relatively weak correlation that was not significant (r = 0.37, p = 0.187; Figure 7A3).

Bottom Line: Control experiments showed that changes in variance with synchrony were primarily due to changes in the CS waveform, as opposed to changes in the strength of field potentials from surrounding cells.Direct counts of spikelets showed that their number increased with synchronization of CS activity.In sum, these results provide evidence of a causal link between two of the distinguishing characteristics of the olivocerebellar system, its ability to generate synchronous activity and the waveform of the CS.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroscience and Physiology, New York University School of Medicine New York, NY, USA.

ABSTRACT
Purkinje cells (PCs) generate complex spikes (CSs) when activated by the olivocerebellar system. Unlike most spikes, the CS waveform is highly variable, with the number, amplitude, and timing of the spikelets that comprise it varying with each occurrence. This variability suggests that CS waveform could be an important control parameter of olivocerebellar activity. The origin of this variation is not well known. Thus, we obtained extracellular recordings of CSs to investigate the possibility that the electrical coupling state of the inferior olive (IO) affects the CS waveform. Using multielectrode recordings from arrays of PCs we showed that the variance in the recording signal during the period when the spikelets occur is correlated with CS synchrony levels in local groups of PCs. The correlation was demonstrated under both ketamine and urethane, indicating that it is robust. Moreover, climbing fiber reflex evoked CSs showed an analogous positive correlation between spikelet-related variance and the number of cells that responded to a stimulus. Intra-IO injections of GABA-A receptor antagonists or the gap junction blocker carbenoxolone produced correlated changes in the variance and synchrony levels, indicating the presence of a causal relationship. Control experiments showed that changes in variance with synchrony were primarily due to changes in the CS waveform, as opposed to changes in the strength of field potentials from surrounding cells. Direct counts of spikelets showed that their number increased with synchronization of CS activity. In sum, these results provide evidence of a causal link between two of the distinguishing characteristics of the olivocerebellar system, its ability to generate synchronous activity and the waveform of the CS.

No MeSH data available.