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Locomotion-Related Population Cortical Ca 2+ Transients in Freely Behaving Mice

View Article: PubMed Central - PubMed

ABSTRACT

Locomotion involves complex neural activity throughout different cortical and subcortical networks. The primary motor cortex (M1) receives a variety of projections from different brain regions and is responsible for executing movements. The primary visual cortex (V1) receives external visual stimuli and plays an important role in guiding locomotion. Understanding how exactly the M1 and the V1 are involved in locomotion requires recording the neural activities in these areas in freely moving animals. Here, we used an optical fiber-based method for the real-time monitoring of neuronal population activities in freely moving mice. We combined the bulk loading of a synthetic Ca2+ indicator and the optical fiber-based Ca2+ recordings of neuronal activities. An optical fiber 200 μm in diameter can detect the coherent activity of a subpopulation of neurons. In layer 5 of the M1 and V1, we showed that population Ca2+ transients reliably occurred preceding the impending locomotion. Interestingly, the M1 Ca2+ transients started ~100 ms earlier than that in V1. Furthermore, the population Ca2+ transients were robustly correlated with head movements. Thus, our work provides a simple but efficient approach for monitoring the cortical Ca2+ activity of a local cluster of neurons during locomotion in freely moving animals.

No MeSH data available.


Related in: MedlinePlus

Population Ca2+ transients of the M1 in freely moving and resting (quiescent but not sleeping) states. (A) Left panel, scheme of the recording setup where Ca2+ transients and behavior were recorded simultaneously. Right panel, the actual recording condition. (B) Ca2+ transients of the M1 in freely moving and resting (but not sleeping) states. (C) Comparison of population Ca2+ transient frequencies in the M1 in freely moving and resting states in the first min after the mice were placed in the box (n = 8 mice; Wilcoxon signed-rank test, ***p < 0.001). (D) Comparison of population Ca2+ transient amplitudes in the M1 in freely moving and resting states (n = 8 mice; Wilcoxon signed-rank test, ***p < 0.001). (E) Example showing body movements (red) and simultaneously-recorded fluorescence (purple) from a green fluorescent protein (GFP) transgenic mouse during freely moving state. (F) Distribution of the amplitudes of OGB-1 and GFP fluorescence. Both fit Gaussian distributions and the mean values were 0.3% ΔF/F and 1.5% ΔF/F, respectively. Values are the mean ± SEM.
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Figure 3: Population Ca2+ transients of the M1 in freely moving and resting (quiescent but not sleeping) states. (A) Left panel, scheme of the recording setup where Ca2+ transients and behavior were recorded simultaneously. Right panel, the actual recording condition. (B) Ca2+ transients of the M1 in freely moving and resting (but not sleeping) states. (C) Comparison of population Ca2+ transient frequencies in the M1 in freely moving and resting states in the first min after the mice were placed in the box (n = 8 mice; Wilcoxon signed-rank test, ***p < 0.001). (D) Comparison of population Ca2+ transient amplitudes in the M1 in freely moving and resting states (n = 8 mice; Wilcoxon signed-rank test, ***p < 0.001). (E) Example showing body movements (red) and simultaneously-recorded fluorescence (purple) from a green fluorescent protein (GFP) transgenic mouse during freely moving state. (F) Distribution of the amplitudes of OGB-1 and GFP fluorescence. Both fit Gaussian distributions and the mean values were 0.3% ΔF/F and 1.5% ΔF/F, respectively. Values are the mean ± SEM.

Mentions: To investigate the correlation between the population Ca2+ transients and the body movements, we recorded Ca2+ activities in layer 5 neurons of the M1 in freely behaving mice in a white, opaque, rectangular chamber (Figure 3A). Mouse behavior was recorded with a camera that was placed above the recording chamber. The recordings were performed at least 2 h after anesthesia was ended. Figure 3B shows a representative recording of Ca2+ transients obtained from one mouse in both freely moving (upper) and resting (quiescent, but not sleeping; lower) states. In this example, when the mouse was moving freely, Ca2+ transients were observed with a high frequency, while almost no transients were observed in the resting states. On average, both the frequency (Figure 3C; moving: 0.32 ± 0.04 Hz vs. resting: 0.08 ± 0.01 Hz; p < 0.001, n = 8 mice, Wilcoxon signed-rank test) and amplitude (Figure 3D; moving: 1.51% ± 0.06% ΔF/F vs. resting: 0.24% ± 0.02% ΔF/F; p < 0.001, n = 8 mice, Wilcoxon signed-rank test) of the Ca2+ transients in the moving states were significantly higher than those in resting states. As a control, these signals were not seen in the mice whose layer 5 neurons expressed green fluorescent protein (GFP; Figures 3E,F).


Locomotion-Related Population Cortical Ca 2+ Transients in Freely Behaving Mice
Population Ca2+ transients of the M1 in freely moving and resting (quiescent but not sleeping) states. (A) Left panel, scheme of the recording setup where Ca2+ transients and behavior were recorded simultaneously. Right panel, the actual recording condition. (B) Ca2+ transients of the M1 in freely moving and resting (but not sleeping) states. (C) Comparison of population Ca2+ transient frequencies in the M1 in freely moving and resting states in the first min after the mice were placed in the box (n = 8 mice; Wilcoxon signed-rank test, ***p < 0.001). (D) Comparison of population Ca2+ transient amplitudes in the M1 in freely moving and resting states (n = 8 mice; Wilcoxon signed-rank test, ***p < 0.001). (E) Example showing body movements (red) and simultaneously-recorded fluorescence (purple) from a green fluorescent protein (GFP) transgenic mouse during freely moving state. (F) Distribution of the amplitudes of OGB-1 and GFP fluorescence. Both fit Gaussian distributions and the mean values were 0.3% ΔF/F and 1.5% ΔF/F, respectively. Values are the mean ± SEM.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
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Figure 3: Population Ca2+ transients of the M1 in freely moving and resting (quiescent but not sleeping) states. (A) Left panel, scheme of the recording setup where Ca2+ transients and behavior were recorded simultaneously. Right panel, the actual recording condition. (B) Ca2+ transients of the M1 in freely moving and resting (but not sleeping) states. (C) Comparison of population Ca2+ transient frequencies in the M1 in freely moving and resting states in the first min after the mice were placed in the box (n = 8 mice; Wilcoxon signed-rank test, ***p < 0.001). (D) Comparison of population Ca2+ transient amplitudes in the M1 in freely moving and resting states (n = 8 mice; Wilcoxon signed-rank test, ***p < 0.001). (E) Example showing body movements (red) and simultaneously-recorded fluorescence (purple) from a green fluorescent protein (GFP) transgenic mouse during freely moving state. (F) Distribution of the amplitudes of OGB-1 and GFP fluorescence. Both fit Gaussian distributions and the mean values were 0.3% ΔF/F and 1.5% ΔF/F, respectively. Values are the mean ± SEM.
Mentions: To investigate the correlation between the population Ca2+ transients and the body movements, we recorded Ca2+ activities in layer 5 neurons of the M1 in freely behaving mice in a white, opaque, rectangular chamber (Figure 3A). Mouse behavior was recorded with a camera that was placed above the recording chamber. The recordings were performed at least 2 h after anesthesia was ended. Figure 3B shows a representative recording of Ca2+ transients obtained from one mouse in both freely moving (upper) and resting (quiescent, but not sleeping; lower) states. In this example, when the mouse was moving freely, Ca2+ transients were observed with a high frequency, while almost no transients were observed in the resting states. On average, both the frequency (Figure 3C; moving: 0.32 ± 0.04 Hz vs. resting: 0.08 ± 0.01 Hz; p < 0.001, n = 8 mice, Wilcoxon signed-rank test) and amplitude (Figure 3D; moving: 1.51% ± 0.06% ΔF/F vs. resting: 0.24% ± 0.02% ΔF/F; p < 0.001, n = 8 mice, Wilcoxon signed-rank test) of the Ca2+ transients in the moving states were significantly higher than those in resting states. As a control, these signals were not seen in the mice whose layer 5 neurons expressed green fluorescent protein (GFP; Figures 3E,F).

View Article: PubMed Central - PubMed

ABSTRACT

Locomotion involves complex neural activity throughout different cortical and subcortical networks. The primary motor cortex (M1) receives a variety of projections from different brain regions and is responsible for executing movements. The primary visual cortex (V1) receives external visual stimuli and plays an important role in guiding locomotion. Understanding how exactly the M1 and the V1 are involved in locomotion requires recording the neural activities in these areas in freely moving animals. Here, we used an optical fiber-based method for the real-time monitoring of neuronal population activities in freely moving mice. We combined the bulk loading of a synthetic Ca2+ indicator and the optical fiber-based Ca2+ recordings of neuronal activities. An optical fiber 200 &mu;m in diameter can detect the coherent activity of a subpopulation of neurons. In layer 5 of the M1 and V1, we showed that population Ca2+ transients reliably occurred preceding the impending locomotion. Interestingly, the M1 Ca2+ transients started ~100 ms earlier than that in V1. Furthermore, the population Ca2+ transients were robustly correlated with head movements. Thus, our work provides a simple but efficient approach for monitoring the cortical Ca2+ activity of a local cluster of neurons during locomotion in freely moving animals.

No MeSH data available.


Related in: MedlinePlus