Locomotion-Related Population Cortical Ca2+ Transients in Freely Behaving Mice

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.

Multidimensional Tuning in Motor Cortical Neurons during Active Behavior

“…These findings suggest motor cortex as a dynamic substrate that actively integrates diverse streams of information to contribute to sensorimotor learning and performance. However, the potential influence of various multimodal inputs on motor cortical activity during behavior is difficult to assess in anesthetized and/or restrained experimental paradigms that focus on a single motor task; recordings in freely behaving animals, especially in the context of sensorimotor skill learning, afford opportunities for investigating sensorimotor integration in motor cortical neurons ( Ebbesen et al, 2017 ; Zhang et al, 2017 ; Mimica et al, 2018 ).…”

Multi-dimensional tuning in motor cortical neurons during active behavior

“…Taken together, these findings suggest motor cortex as a dynamic substrate that actively integrates diverse streams of information to contribute to sensorimotor learning and performance. However, the potential influence of various multi-modal inputs on motor cortical activity during behavior is difficult to assess in anesthetized and/or restrained experimental paradigms that focus on a single motor task; recordings in freely behaving animals, especially in the context of sensorimotor skill learning, provide an attractive alternative for investigating sensorimotor integration in motor cortical neurons (Ebbesen et al, 2017;Zhang et al, 2017;Mimica et al, 2018).…”

Multichannel fiber photometry for mapping axonal terminal activity in a restricted brain region in freely moving mice

“…Ca 2þ recording data were analyzed similar to previous work. 7,23,28 The data were filtered with a Savitzky-Golay FIR smoothing filter (five side points and three polynomial order).…”

“…22 Although it has poorer spatial resolution compared to the imaging approaches described above, fiber photometry can be used to record the activity of a group of neuronal cell bodies or axonal terminals in many brain regions in freely moving animals. 1,7,[23][24][25][26][27][28][29][30][31] Combined with genetic tools, one can perform fiber photometry recordings in axonal terminals in a cell-type and long-term manner. For example, Gunaydin et al 1 showed that the activity patterns of the axonal terminals from VTA to nucleus accumbens encoded and predicted key features of social behavior.…”