Limits...
Sub-Millisecond Firing Synchrony of Closely Neighboring Pyramidal Neurons in Hippocampal CA1 of Rats During Delayed Non-Matching to Sample Task.

Takahashi S, Sakurai Y - Front Neural Circuits (2009)

Bottom Line: The synchrony generally co-occurred with the firing rate modulation in relation to both internal (retention and comparison) and external (stimulus input and motor output) events during the task.However, the synchrony occasionally occurred in relation to stimulus inputs even when rate modulation was clearly absent, suggesting that the synchrony is not simply accompanied with firing rate modulation and that the synchrony and the rate modulation might code similar information independently.We therefore conclude that the sub-millisecond firing synchrony in the hippocampus is an effective carrier for propagating information - as represented by the firing rate modulations - to downstream neurons.

View Article: PubMed Central - PubMed

Affiliation: Khoyama Center for Neuroscience, Faculty of Computer Science and Engineering, Kyoto Sangyo University Kyoto, Japan.

ABSTRACT
Firing synchrony among neurons is thought to play functional roles in several brain regions. In theoretical analyses, firing synchrony among neurons within sub-millisecond precision is feasible to convey information. However, little is known about the occurrence and the functional significance of the sub-millisecond synchrony among closely neighboring neurons in the brain of behaving animals because of a technical issue: spikes simultaneously generated from closely neighboring neurons are overlapped in the extracellular space and are not easily separated. As described herein, using a unique spike sorting technique based on independent component analysis together with extracellular 12-channel multi-electrodes (dodecatrodes), we separated such overlapping spikes and investigated the firing synchrony among closely neighboring pyramidal neurons in the hippocampal CA1 of rats during a delayed non-matching to sample task. Results showed that closely neighboring pyramidal neurons in the hippocampal CA1 can co-fire with sub-millisecond precision. The synchrony generally co-occurred with the firing rate modulation in relation to both internal (retention and comparison) and external (stimulus input and motor output) events during the task. However, the synchrony occasionally occurred in relation to stimulus inputs even when rate modulation was clearly absent, suggesting that the synchrony is not simply accompanied with firing rate modulation and that the synchrony and the rate modulation might code similar information independently. We therefore conclude that the sub-millisecond firing synchrony in the hippocampus is an effective carrier for propagating information - as represented by the firing rate modulations - to downstream neurons.

No MeSH data available.


Related in: MedlinePlus

SSSs related to motor outputs are associated with firing rate modulations. Comparison of SSSs and rate modulations between non-match/match (go/no-go) trials was selected in this example. Each subfigure averages all correct trials of a session. Results of U-tests of 11 s of tone presentation in the preceding trial, 5 s of delay, and 2 s of tone presentation in the next trial are shown. (A) Firing rates of neuron 9 in match (red) and non-match (blue) trials. (B,C) Raster plots of spikes of neuron 9 in match (red) and non-match (blue) trials. (D) P-values of neuron 9 for a difference between rates in match trials and in non-match trials. (E) Firing rates of neuron 10. (F,G) Raster plots of neuron 10. (H) P-values of neuron 10. (I) Rates of the SSS between neurons 9 and 10. (J–M) In copies of raster plots from (B), (C), (F), and (G) (black dots), SSSs are shown as green dots. (N) P-value of the SSS between neurons 9 and 10. The significant firing rates of neurons 9 and 10 are associated with SSS. Additional details are presented in Figure 5 and described in Section ‘Materials and Methods’.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2742662&req=5

Figure 7: SSSs related to motor outputs are associated with firing rate modulations. Comparison of SSSs and rate modulations between non-match/match (go/no-go) trials was selected in this example. Each subfigure averages all correct trials of a session. Results of U-tests of 11 s of tone presentation in the preceding trial, 5 s of delay, and 2 s of tone presentation in the next trial are shown. (A) Firing rates of neuron 9 in match (red) and non-match (blue) trials. (B,C) Raster plots of spikes of neuron 9 in match (red) and non-match (blue) trials. (D) P-values of neuron 9 for a difference between rates in match trials and in non-match trials. (E) Firing rates of neuron 10. (F,G) Raster plots of neuron 10. (H) P-values of neuron 10. (I) Rates of the SSS between neurons 9 and 10. (J–M) In copies of raster plots from (B), (C), (F), and (G) (black dots), SSSs are shown as green dots. (N) P-value of the SSS between neurons 9 and 10. The significant firing rates of neurons 9 and 10 are associated with SSS. Additional details are presented in Figure 5 and described in Section ‘Materials and Methods’.

Mentions: To confirm whether SSSs can code information as well as rate modulations, we analyzed the relation between the SSSs of closely neighboring neurons and behavioral events during the DNMS task. We used a non-parametric statistical U-test because it is often difficult to predict the type of distribution of neuronal firing rates. In this experiment, we defined groups of simultaneously monitored neurons from one dodecatrode as a local neuron group. In our spike sorting, each local neuron group was shown to consist of two to six pyramidal neurons. In all, 13 groups were analyzed. During the sample, delay, and test periods of the DNMS task, both the SSSs and rate modulations were analyzed in relation to behavioral events, i.e., stimulus inputs, stimulus retention, motor outputs, and comparison of the stimuli. At least two groups showed that SSSs and firing rate modulations of participating neurons were coupled and correlated with stimulus inputs (Figure 5N), stimulus retention (Figure 6N), motor outputs (Figure 7N), and comparison of stimuli (Figure 8N), respectively.


Sub-Millisecond Firing Synchrony of Closely Neighboring Pyramidal Neurons in Hippocampal CA1 of Rats During Delayed Non-Matching to Sample Task.

Takahashi S, Sakurai Y - Front Neural Circuits (2009)

SSSs related to motor outputs are associated with firing rate modulations. Comparison of SSSs and rate modulations between non-match/match (go/no-go) trials was selected in this example. Each subfigure averages all correct trials of a session. Results of U-tests of 11 s of tone presentation in the preceding trial, 5 s of delay, and 2 s of tone presentation in the next trial are shown. (A) Firing rates of neuron 9 in match (red) and non-match (blue) trials. (B,C) Raster plots of spikes of neuron 9 in match (red) and non-match (blue) trials. (D) P-values of neuron 9 for a difference between rates in match trials and in non-match trials. (E) Firing rates of neuron 10. (F,G) Raster plots of neuron 10. (H) P-values of neuron 10. (I) Rates of the SSS between neurons 9 and 10. (J–M) In copies of raster plots from (B), (C), (F), and (G) (black dots), SSSs are shown as green dots. (N) P-value of the SSS between neurons 9 and 10. The significant firing rates of neurons 9 and 10 are associated with SSS. Additional details are presented in Figure 5 and described in Section ‘Materials and Methods’.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2742662&req=5

Figure 7: SSSs related to motor outputs are associated with firing rate modulations. Comparison of SSSs and rate modulations between non-match/match (go/no-go) trials was selected in this example. Each subfigure averages all correct trials of a session. Results of U-tests of 11 s of tone presentation in the preceding trial, 5 s of delay, and 2 s of tone presentation in the next trial are shown. (A) Firing rates of neuron 9 in match (red) and non-match (blue) trials. (B,C) Raster plots of spikes of neuron 9 in match (red) and non-match (blue) trials. (D) P-values of neuron 9 for a difference between rates in match trials and in non-match trials. (E) Firing rates of neuron 10. (F,G) Raster plots of neuron 10. (H) P-values of neuron 10. (I) Rates of the SSS between neurons 9 and 10. (J–M) In copies of raster plots from (B), (C), (F), and (G) (black dots), SSSs are shown as green dots. (N) P-value of the SSS between neurons 9 and 10. The significant firing rates of neurons 9 and 10 are associated with SSS. Additional details are presented in Figure 5 and described in Section ‘Materials and Methods’.
Mentions: To confirm whether SSSs can code information as well as rate modulations, we analyzed the relation between the SSSs of closely neighboring neurons and behavioral events during the DNMS task. We used a non-parametric statistical U-test because it is often difficult to predict the type of distribution of neuronal firing rates. In this experiment, we defined groups of simultaneously monitored neurons from one dodecatrode as a local neuron group. In our spike sorting, each local neuron group was shown to consist of two to six pyramidal neurons. In all, 13 groups were analyzed. During the sample, delay, and test periods of the DNMS task, both the SSSs and rate modulations were analyzed in relation to behavioral events, i.e., stimulus inputs, stimulus retention, motor outputs, and comparison of the stimuli. At least two groups showed that SSSs and firing rate modulations of participating neurons were coupled and correlated with stimulus inputs (Figure 5N), stimulus retention (Figure 6N), motor outputs (Figure 7N), and comparison of stimuli (Figure 8N), respectively.

Bottom Line: The synchrony generally co-occurred with the firing rate modulation in relation to both internal (retention and comparison) and external (stimulus input and motor output) events during the task.However, the synchrony occasionally occurred in relation to stimulus inputs even when rate modulation was clearly absent, suggesting that the synchrony is not simply accompanied with firing rate modulation and that the synchrony and the rate modulation might code similar information independently.We therefore conclude that the sub-millisecond firing synchrony in the hippocampus is an effective carrier for propagating information - as represented by the firing rate modulations - to downstream neurons.

View Article: PubMed Central - PubMed

Affiliation: Khoyama Center for Neuroscience, Faculty of Computer Science and Engineering, Kyoto Sangyo University Kyoto, Japan.

ABSTRACT
Firing synchrony among neurons is thought to play functional roles in several brain regions. In theoretical analyses, firing synchrony among neurons within sub-millisecond precision is feasible to convey information. However, little is known about the occurrence and the functional significance of the sub-millisecond synchrony among closely neighboring neurons in the brain of behaving animals because of a technical issue: spikes simultaneously generated from closely neighboring neurons are overlapped in the extracellular space and are not easily separated. As described herein, using a unique spike sorting technique based on independent component analysis together with extracellular 12-channel multi-electrodes (dodecatrodes), we separated such overlapping spikes and investigated the firing synchrony among closely neighboring pyramidal neurons in the hippocampal CA1 of rats during a delayed non-matching to sample task. Results showed that closely neighboring pyramidal neurons in the hippocampal CA1 can co-fire with sub-millisecond precision. The synchrony generally co-occurred with the firing rate modulation in relation to both internal (retention and comparison) and external (stimulus input and motor output) events during the task. However, the synchrony occasionally occurred in relation to stimulus inputs even when rate modulation was clearly absent, suggesting that the synchrony is not simply accompanied with firing rate modulation and that the synchrony and the rate modulation might code similar information independently. We therefore conclude that the sub-millisecond firing synchrony in the hippocampus is an effective carrier for propagating information - as represented by the firing rate modulations - to downstream neurons.

No MeSH data available.


Related in: MedlinePlus