Automated Multichannel Bidirectional Fiber Optic Rotary Device for Brain-Behavior Studies

Chisquare Bioimaging, Llc, Brookline MA

Investigators

Abstract

The project proposed herein addresses an urgent need for approaches that allow minimally invasive long term optical recording deep in a mouse brain with high spatial and high temporal resolution. Understanding the causal relationship between brain neural activity and behavior is among the research priorities of NIAAA and one of the main objectives of the BRAIN initiative. A lot of progress has been made to optically perturb and monitor neural circuit dynamics during behavior. However, the practical implementation is still largely limited to one location in the brain at a time, and there is still an urgent need for simultaneous minimally invasive long time optical recording deep in the brain at multiple sites with spatial and temporal resolution. Simultaneous recordings at multiple sites will allow neuroscientists to gain new insights by constructing a global view on the timing and synchrony of biochemical signals among neurons, projections, and different brain regions. They shed light on neural mechanisms underlying normal behavior and behavior associated with alcohol addiction, drug addiction, Parkinson?s disease, and other neuromuscular and neuropsychiatric diseases in freely moving rodents. The proposed project aims to design an automated multichannel bidirectional FORJ that will allow the simultaneous transfer of optical signals to and from multiple sites of the brain through a rotating interface and with minimal mechanical impact on the natural behavior in a freely moving mouse. The first aim is to build a two-channel bidirectional FORJ prototype device. The design principle, in a nutshell, is to dynamically measure, using an angle encoder, the movement of a mouse and automatically release the torsion in the optical cable by engaging a brushless DC motor to unwind the twisted optical fiber by n number of 360° turns. To optimize its efficiency, the unwinding process is activated automatically only when the angle encoder reaches an experimentally determined threshold. The second aim is to perform tests to validate and quantitatively characterize overall light throughput, transmission variation over rotation, starting torque, and synchronization of the FORJ with data acquisition. Finally, on the basis of the two-channel FORJ, a four-channel FORJ will be built by extending the channel capacity. The project proposed in this application takes a unique approach by combining optical design and rotational sensing to reduce the optical design complexity and reduce the number of mechanical moving parts in order to improve signal-to-noise ratio. The multichannel bidirectional FORJ potentially offers the alcohol addiction research community expanded capability to investigate ethanol effects on learning and decision making. More broadly, it offers the neuroscience community the possibilities to investigate the causal relationship between dynamic biochemical activity of neuronal circuits and behavior across spatial and temporal scales.