Shiba Inu (detailed introduction)

　　The British Daily Mail reported that dogs’ sense of smell is a thousand times more sensitive than humans’, and a recent study utilized this olfactory ability to reveal the special place human owners hold in dogs’ minds. The study found that key regions in the canine brain only light up when smelling their owner’s scent, while the same regions do not activate when puppies smell other dogs — even familiar companion dogs, said researchers from Emory University in Georgia, USA.
　　"Therefore, we believe this reaction reflects a kind of positive emotional response similar to that caused by familiar human scents," said Gregory Berns, leader of the study team. Published in the journal Behavioral Processes, the study involved training a dozen dogs to remain still inside an MRI machine without sedation or restraints.
　　This allowed researchers to observe two regions in the dog brain: the olfactory bulb — indicating activation of the animal’s sense of smell — and the caudate nucleus. According to prior studies, the caudate nucleus in other mammals, including humans, is involved in processing positive anticipation such as social rewards. During the 30-minute MRI scans, these 12 dogs were exposed to five different scents from themselves, another dog living under the same roof, an unfamiliar dog, a familiar human, and an unfamiliar human the dog had never met.
　　Researchers found that the olfactory bulb was "activated to a similar degree" for every scent. However, the scent of the familiar human activated the olfactory bulb more significantly. "Dogs not only can distinguish this scent from others, but also associate it positively. This proves dogs’ sensitive olfaction and provides clues to the importance of humans in dogs’ lives."
　　However, Professor Berns added they were not certain whether it was the person themselves, or the person’s behavior — such as providing food — that triggered this positive response. "Although this possibility exists, we think it’s unlikely because most familiar humans to dogs are not their primary caregivers."
　　This study builds on previous research conducted by the same team, which found that brain regions related to "feeling" in dogs are the same as in humans. Professor Berns stated that there is a remarkable similarity in the structure and function of an important brain region in both dogs and humans: the caudate nucleus. Located between the brainstem and the cortex, it is rich in dopamine receptors. The team found that when dogs faced gesture cues hinting at the presence of food, activity in the caudate nucleus increased. "Do these findings prove dogs love humans? Not necessarily. But many things that activate the human caudate nucleus — mainly related to positive emotions — also activate the dog’s caudate nucleus."
　　Neuroscientists call this functional homology, which may underpin emotionality in dogs. This capacity to experience positive emotions, such as love and attachment, may suggest that dogs possess sensory abilities similar to human children.