Human brains process lexical meaning separately from the emotional prosody of speech at higher levels of the processing hierarchy. Dog brains can also dissociate lexical and emotional prosodic information in human spoken words. However, little is known on what is going on in their minds during these.
To better understand the neural dynamics of lexical processing in the dog brain, a new study by Hungarian researchers at the Department of Ethology, Faculty of Science, Eötvös Loránd University (ELTE) used functional MRI on awake dogs. Dogs listened to known, praise words (clever, well done, that’s it) and unknown, neutral words (such, as if, yet) both in praising and neutral intonation.
Anna Gábor, the postdoctoral researcher at the MTA-ELTE ‘Lendület’ Neuroethology of Communication Research Group, lead author of the study, explains, “Exploring speech processing similarities and differences between dog and human brains can help a lot in understanding the steps that led to the emergence of speech during evolution. Human brains process speech hierarchically: first, intonations at lower-, next, word meanings at higher stages. Some years ago, we discovered that dog brains, just as human brains, separate intonation, and word meaning.”
“But is the hierarchy also similar? To find it out, we used a special technique this time: we measured how dog brain activity decreases to repeatedly played stimuli. During brain scanning, sometimes we repeated words, sometimes intonations. A stronger decrease in a given brain region to certain repetitions shows the region’s involvement.”
Attila Andics, a principal investigator of the MTA-ELTE ‘Lendület’ Neuroethology of Communication Research Group, said, “Although speech processing in humans is unique in many aspects, this study revealed interesting similarities between us and a speechless species. The similarity does not imply, however, that this hierarchy evolved for speech processing. Instead, the hierarchy following intonation and word meaning processing reported here and also in humans may reflect a more general, not speech-specific processing principle.”
“Simpler, emotionally loaded cues (such as intonation) are typicaanalyzedysed at lower stages, while more compllearnedarnt cues (such as word meaning) analyzed at higher stages in multiple species. What our results really shed light on is that human speech processing may also follow this more basic, more general hierarchy.”
Journal Reference:
- Gábor, A., Gácsi, M., Szabó, D. et al. Multilevel fMRI adaptation for spoken word processing in the awake dog brain. Sci Rep 10, 11968 (2020). DOI: 10.1038/s41598-020-68821-6