Speech Detection and Language Representation in Dog's Brain
Dogs have been confirmed to detect speech naturalness and distinguish between languages according to a recent research(Nature Journal).
As companion animals, dogs are constantly exposed to human languages and speech for their lifetime. Findings have therefore revealed that speech detection and language discrimination dogs is under the control of separate cortical regions, as opposed to humans in which these processes are supported by the superior temporal cortex.
According to the study, functional magnetic resonance imaging (fMRI) which uses MR imaging to measure small changes in blood flow that take place in an active part of the brain, was used to conduct the test on eighteen adult family dogs who participated in the research.
The group comprises of six different breeds of dog (golden retriever, border collies, Australian shepherd, labradoodle, cocker spaniel and mixed breeds) with prior training to stay still in a MRI scanner so as to enhance the the accuracy of the result, as the sound of the scanner may cause uneasiness to the participants, which will alter the result of the fMRI which images metabolic function.
The dogs were exposed to the stimuli, which consist of speech from a familiar, unfamiliar language( Hungarian and Spanish) and a scrambled speech made from several fragments of an original speech. Some of the dogs had Spanish spoken in their environment, while others had Hungarian.
The representation of the speech detection on the bilateral auditory cortical regions of the brain was different for natural speech and scrambled speech. The familiar and unfamiliar languages were also distinctly represented in the secondary auditory cortex and the precruciate gyrus. It's of great interest to note that dog's brain can distinguish between two languages in the same rhythm class, because it can pick auditory regularities of a particular language.
However, older dogs show greater difference in their cortical representation of the familiar and unfamiliar language, which is believed to be based on their language exposure.
It is also revealed that there are breed differences in the auditory representation of the naturalness of a speech, as greater auditory sensitivity was shown in longer-headed dogs in their right auditory region.
Speech detection and language distinction are enhanced by the stress, pitch and syllables regularity. The sensitivity of Dogs to several signals in speech can therefore be used in processing the identity of a speaker, the familiarity of a word and what a word conotes.
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