A cost-effective, simple measure of emotional response in the brain for use by behavioral biologists

Studies combining brain activity measures with behavior have the potential to reveal more about animal cognition than either on their own. However, brain measure procedures in animal studies are often practically challenging and cost-prohibitive. Therefore, we test whether a simple measure of ear temperature can be used to index hemispheric brain activation using a handheld thermoscanner. Cortisol levels are correlated with the activation of the right cortical region, implying that, when stressful situations are experienced, increased right hemisphere activation occurs. This leads to corresponding locally detectable increases in ipsilateral ear temperature.

We compared right-and left-ear temperatures of 32 domestic dogs under non-stressful and partially stressful conditions.

We detected significant elevations in right-ear temperature - but not left-ear temperature - relative to baseline readings in the partially stressful condition that were not detected in the non-stressful condition.

These findings provide encouraging support for the notion that tympanic membrane temperature readings can provide a simple index for canine hemispheric brain activation, which can be combined with data on behavioral decision-making, expectancy violations, or other measures of emotional processing. Devices are cheap, simple to use, portable, and only minimally invasive providing a means for realtime brain and behavior measurements to be conducted in real-world settings.