Functional Magnetic Resonance Imaging of the Domestic Dog: Research, Methodology, and Conceptual Issues

Abstract

Neuroimaging of the domestic dog is a rapidly expanding research topic in terms of the cognitive domains being investigated. Because dogs have shared both a physical and social world with humans for thousands of years, they provide a unique and socially relevant means of investigating a variety of shared human and canine psychological phenomena. Additionally, their trainability allows for neuroimaging to be carried out noninvasively in an awake and unrestrained state. In this review, a brief overview of functional magnetic resonance imaging (fMRI) is followed by an analysis of recent research with dogs using fMRI. Methodological and conceptual concerns found across multiple studies are raised, and solutions to these issues are suggested. With the research capabilities brought by canine functional imaging, findings may improve our understanding of canine cognitive processes, identify neural correlates of behavioral traits, and provide early-life selection measures for dogs in working roles.

Separate brain areas for processing human and dog faces as revealed by awake fMRI in dogs (Canis familiaris)

“…In order to determine connectivity fingerprints for each subject, 19 Btargets^were identified. These included regions of interest (ROIs) involved in basic sensory, social, and cognitive functions in the dog brain, which have also been implicated in guiding canine behavior in previous dog fMRI studies (Andics et al, 2014(Andics et al, , 2016Berns et al, 2012Berns et al, , 2015Berns et al, , 2016Cook et al, 2014;Cuaya et al, 2016;Dilks et al, 2015;Jia et al, 2014Jia et al, , 2015Kyathanahally et al, 2015;Thompkins et al, 2016;Ramahihgari et al, 2018). Figure 1 illustrates the spatial locations of these regions in the dog and human brains, while Table 2 shows the MNI coordinates of these regions in the human brain.…”

“…Figure 1 illustrates the spatial locations of these regions in the dog and human brains, while Table 2 shows the MNI coordinates of these regions in the human brain. For the dogs, authors who were well versed with canine neuroanatomy manually marked these target regions (in our own custom standardized space as discussed in our previous publications (Jia et al, 2014(Jia et al, , 2015Kyathanahally et al, 2015;Thompkins et al, 2016)). The locations of the dog regions were also motivated by findings in previous dog fMRI studies cited above.…”

“…Recent evidence also indicates that there is a face-selective area in the dog brain of pet dogs for processing human and dog faces (Cuaya, Hernández-Pérez, & Cocha, 2016;Dilks et al, 2015). Using functional magnetic resonance imaging (fMRI) in awake dogs trained for detection (for reviews see Bunford, Andics, Kis, Miklósi, & Gácsi, 2017;Thompkins, Deshpande, Waggoner, & Katz, 2016), we investigated nuances in face regions of the domestic dog specific to cross-species stimulus processing and evolutionary origins of face processing. By comparing neural activation resultant of viewing human and dog face stimuli, we have identified adjacent but separate brain areas for processing of human faces and dog faces by domestic dogs.…”

Training pet dogs for eye-tracking and awake fMRI

“…The precise spatial localization of neural activity in the relatively small dog brain therefore requires that the dog lie motionless in the noisy, vibrating, and spatially restrained MRI scanner bore. Because anesthesia or sedation would negatively affect both brain function and cognition, by impeding attentiveness, altering the state of consciousness, and reducing rates of blood flow and respiration (Thompkins, Deshpande, Waggoner, & Katz, 2016), alternative ways are needed to achieve stillness. For the same reasons we described for eye-tracking, testing animals that, due to their training, stay in the scanner on a voluntary basis is highly preferred over physical restriction.…”

“…Due to various unpredictable circumstances or to events unrelated to dog training-such as dogs that become sick, caregivers stopping participation for personal reasons, and so forth-we cannot compare the different variations quantitatively in terms of training success (e.g., the ratio of dogs that have been tested successfully of all dogs with which the researchers started training). Still, the overarching goal of any training methodology is to reduce training time while maintaining success in the desired behavior (Thompkins et al, 2016).…”