Tracking multineuronal activity in unrestrained animals with a random access two photon microscopy*

Optical recordings of neuronal activity in freely behaving animals can reveal the correlation between the neural activity and behavioral outcome, such as decision making, learning, and multisensory integration. Such recordings require a microscopy that can overcome motion artifacts that accompany behavior. We recently developed a two-photon tracking microscope capable of recording activity from neurons in freely behaving larval fruit flies without motion artifacts[1]. However, due to the inertia of the scanning elements, the current technique is limited to recording only two neurons at a time. In order to study the correlation between neural activities and behavioral outcome across a range of neurons - sensory to motor neurons, it is essential to track multiple neurons at a time.

We extended the microscope using acousto-optic deflectors to relocate the laser beam in a constant time regardless of the distance between the two positions. Combined with improved feedback algorithms implemented in field-programmable gate arrays, this allows us to track and record the activities of many neurons at a high spatio-temporal resolution.

[1] D. Karagyozov, M. M. Skanata, A. Lesar, M. Gershow. Cell Reports. doi 10.1016/j.celrep.2018.10.013