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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.


Demonstration of the windows used for variance measurements. The windows used to measure signal variance are illustrated: B (baseline), S (spikelet), N (non-spikelet), and T (total). (A,B) each present a sample CS waveform recorded from PC soma and dendrite.
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Figure 1: Demonstration of the windows used for variance measurements. The windows used to measure signal variance are illustrated: B (baseline), S (spikelet), N (non-spikelet), and T (total). (A,B) each present a sample CS waveform recorded from PC soma and dendrite.

Mentions: We define several time windows for which variance measurements will be made (Figure 1A). The first is the total spikelet window (T), which is a fixed duration window that starts at the termination of the initial spike, and lasts long enough so that all (or nearly all) spikelets from any CS from the recorded PC will occur within it. The duration was chosen by first visually inspecting an overlay of all CSs and/or an average of all CSs from a PC to determine the approximate times of appropriate start and end points for that PC. The difference in these points set the duration of the T window. The exact duration used was not critical (similar results were obtained when the duration was varied by several milliseconds in test cases). However, if a PC had a few very long outlier CSs, they were excluded from the analysis in order to avoid making the T window excessively long, as that decreased its sensitivity for distinguishing between the vast majority of CSs.


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)

Demonstration of the windows used for variance measurements. The windows used to measure signal variance are illustrated: B (baseline), S (spikelet), N (non-spikelet), and T (total). (A,B) each present a sample CS waveform recorded from PC soma and dendrite.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: Demonstration of the windows used for variance measurements. The windows used to measure signal variance are illustrated: B (baseline), S (spikelet), N (non-spikelet), and T (total). (A,B) each present a sample CS waveform recorded from PC soma and dendrite.
Mentions: We define several time windows for which variance measurements will be made (Figure 1A). The first is the total spikelet window (T), which is a fixed duration window that starts at the termination of the initial spike, and lasts long enough so that all (or nearly all) spikelets from any CS from the recorded PC will occur within it. The duration was chosen by first visually inspecting an overlay of all CSs and/or an average of all CSs from a PC to determine the approximate times of appropriate start and end points for that PC. The difference in these points set the duration of the T window. The exact duration used was not critical (similar results were obtained when the duration was varied by several milliseconds in test cases). However, if a PC had a few very long outlier CSs, they were excluded from the analysis in order to avoid making the T window excessively long, as that decreased its sensitivity for distinguishing between the vast majority of CSs.

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.