Cellular Resolution Functional Imaging in Behaving Rats using Voluntary Head Restraint
Benjamin B. Scott, Carlos D. Brody, David W. Tank, (Neuron 80:1-14, 2013)
Ben Scott, a postdoc in the Brody and Tank labs, has developed a system for voluntary head-fixation in rats (Scott, Brody, and Tank, Neuron 2013). Based on the principles of kinematic mounts often used in optics, the system allows precise re-positioning of a rat’s head, across multiple trials of a behavior, with an accuracy of a few microns. This enables cellular-resolution calcium imaging in behaving rats. In addition, because the rats engage the system voluntarily, the approach is amenable to high-throughput training. Thanks to Ben’s work, we can now use the lab’s training facility to teach voluntarily head-fixing rats to perform complex cognitive behaviors requiring many months to train. We are using this is to perform the first cellular-resolution imaging assays of neural activity involved in higher cognitive processes.
The image below (Fig. 6A from Ben’s paper) shows GCaMP3 images of primary visual cortex from a rat looking at oriented bars over multiple trials. In between trials, the rat withdrew from the head fixation apparatus, and later returned for the next trial. As can be clearly seen, individual neurons are easily identifiable and produce clear, orientation-dependent, calcium transients. For even better signal-to-noise, we now use GCaMP6.