Magnetic Resonance Imaging conducted in unrestrained dogs is a new method that creates a fresh way of examining function and structure in the dog brain. The method is humane, cost effective, and it works, not only for dogs in this research context, but as a scaffold for other husbandry behavior training programs. The transferring classical counter-conditioning strategies help the dogs to rapidly acclimate a robust stationing behavior to the scanner environment.
Because the protocol is cost effective, it is generalizable to trainers around the world without regular access to an MRI scanner. For active, auditory exposure sessions, transport the dog to a familiar indoor training room. And play scan audio at the session's specified volume.
After ten seconds, engage in 20 seconds of toy play with the dog while the scanner noise is still audible. After 20 seconds of play, retrieve the toy from the dog and pause the noise. Then wait with the dog in silence without the reward for 10 seconds before starting the next trial.
Conduct one session of 10 trials per week for 12 weeks increasing the decibel volume over the sessions throughout the duration of the training period. To capture the chin target to towel with the dog standing, sitting, or in the down position, click, then treat to allow the dog to investigate the towel. Once the dog will investigate the towel reliably, click then treat for any nose to towel and subsequent chin to towel contact until the towel contact duration reaches at least two seconds for up to five minutes per session.
When the dog will chin target for at least 26 seconds, click then treat for any investigation of the foam chin rest apparatus. After several reinforced investigations of the apparatus, cue rest and click then treat for one to two seconds of chin contact for five to 15 minutes of training until 40 seconds of contact is achieved. For mock MRI stationing sessions, invite the dog to jump or lift the dog into the mock bore and cue the dog to lie down, clicking then treating.
Cue the dog to rest. And click then treat for one to 12 seconds of chin targeting to the foam chin rest in the elevated bore in 5 to 15 minute sessions until the duration increases to 60 seconds. Reinforce less precise approximations of the behavior initially, as the trainer will have the opportunity to selectively reinforce for better alignment precision in later reps.
When the dog can chin target in the mock bore for at least 60 seconds, cue down and rest, and outfit the dog with ear padding. Place scan audio at a barely audible volume between zero and 40 decibels. And click then treat for one to 12 seconds of chin contact in 15 to 30 minute training sessions until the duration lasts at least 107 seconds.
When the dog can sustain five minutes in down stay in the chin rest in the mock bore and mock RF coil, while wearing ear padding with the scanner noise playing at 80 to 110 decibels, stand or sit beside portable mock bore with the mock RF coil, and gesture to the dog to enter the new bore. Cue down and rest, and outfit the animal with ear padding. Place scan audio at 80 to 110 decibels.
And click then treat for 1 to 30 seconds of stationing in the new location. Next probe for the criterion duration, reinforcing at 5 minutes or when the dog breaks. Once the dog has generalized the stationing behavior to criterion in five distinct transfer locations, the dog is ready for data collection in the real MRI environment.
Here, the maximum duration of four dogs trained in this protocol, as demonstrated for the last three sessions at the end of training and the different training locations is shown. The performance was stable at the end of stationing training and all of the dogs transferred to the mock training locations with a max duration equivalent to training. Three of the dogs transferred to the MRI scanner and demonstrated repeated bouts of the max possible duration of 206 seconds.
The one dog that did not transfer to the MRI scanner had a larger head than the other dogs and could not comfortably fit within the coil, likely contributing to its unwillingness to participate in the scans. Once trained to participate in functional MRI scans, we can glean sensory processing information within several modalities. For example, adjacent but different brain areas at the temporal cortex in the dog brain are active for processing dog and human faces.
Green regions represent areas of the brain more active for human faces contrasted with dog faces. While red regions represent areas of the brain more active for dog faces, contrasted with human faces. While the olfactory bulb, periamygdala, anterior olfactory cortex, entorhinal cortex, and piriform lobes are active in both awake and anesthetized dogs, the regions implicating higher order cognitive processing are activated mainly in awake dogs.
The protocol is designed around the idea that head motion is incompatible with a robust chin rest behavior, which is generalized to occur in multiple settings. While canine functional MRI is in its naissance stages, the future is promising for the continued use of humanity's best friend in understanding brain behavior relationships. For example, our findings can advance the understanding of how to better select, train, and employ dogs for tasks that benefit society such as detecting hazardous threats like explosives.
With the robust method of scanner acclimation, the limitations of the utility of the scanner are bound only by the creativity of the researcher's questions and experimental designs.
