Two-Photon Laser Ablation and In Vivo Wide-Field Imaging of Inferior Olive Neurons Revealed the Recovery of Olivocerebellar Circuits in Zebrafish.

Kanae Hiyoshi,Hiroshi Y Yoshikawa,Narumi Fukuda,Sachiko Tsuda,Kaito Saito,Takahisa Matsuzaki

doi:10.3390/ijerph18168357

Abstract

The cerebellum, a brain region with a high degree of plasticity, is pivotal in motor control, learning, and cognition. The cerebellar reserve is the capacity of the cerebellum to respond and adapt to various disorders via resilience and reversibility. Although structural and functional recovery has been reported in mammals and has attracted attention regarding treatments for cerebellar dysfunction, such as spinocerebellar degeneration, the regulatory mechanisms of the cerebellar reserve are largely unidentified, particularly at the circuit level. Herein, we established an optical approach using zebrafish, an ideal vertebrate model in optical techniques, neuroscience, and developmental biology. By combining two-photon laser ablation of the inferior olive (IO) and long-term non-invasive imaging of “the whole brain” at a single-cell resolution, we succeeded in visualization of the morphological changes occurring in the IO neuron population and showed at a single-cell level that structural remodeling of the olivocerebellar circuit occurred in a relatively short period. This system, in combination with various functional analyses, represents a novel and powerful approach for uncovering the mechanisms of the cerebellar reserve, and highlights the potential of the zebrafish model to elucidate the organizing principles of neuronal circuits and their homeostasis in health and disease.

Highlights

A remarkable aspect of the brain is its plasticity, which is essential for brain development, function, and homeostasis [1,2,3,4,5,6]
Wide-field imaging of the ablated fish showed that olivocerebellar circuit recovery began shortly after inferior olive (IO) ablation, i.e., in less than a week. These results indicate that we succeeded in optically inducing acute lesions in the zebrafish IO, and that the recovery process of the olivocerebellar circuit could be visualized in vivo in a non-invasive manner
To address the mechanisms of the cerebellar reserve with a focus on the olivocerebellar circuit (Figure 1a–c), we first examined the distribution of IO neurons in zebrafish

Summary

Introduction

A remarkable aspect of the brain is its plasticity, which is essential for brain development, function, and homeostasis [1,2,3,4,5,6]. As a brain region with a high degree of plasticity, the cerebellum plays pivotal roles in motor control and learning, as well as in cognition [7,8,9,10]. A collection of anatomical and physiological studies have led to numerous insights regarding information processing in the cerebellum, especially regarding synaptic plasticity and learning [11,12,13,14]. A prominent example of cerebellar plasticity is the “cerebellar reserve”, which is the capacity of the cerebellum to compensate and restore function to adapt to injury or other disorders via resistance and plasticity [15]. Motor dysfunction caused by a cerebellectomy or injury could gradually be compensated for and restored [15,16,17,18,19,20].

Results

Discussion

Conclusion