聞香識主人 嗅覺記憶能觸發動物喜怒哀樂

If your dog looks pleased to see you – it is probably because it loves the particular way you smell.

如果你的狗一見到你就顯得很開心的話，有可能是因為它喜歡你散發出的獨特氣味。

The odour of a familiar human apparently lingers like perfume in the animal’s brain – where it triggers an instinctive emotional response, research published yesterday reveals.

根據近日公佈的一份研究顯示，熟悉的人所散發的氣味會如同香水一般深深地存在於動物的腦海裏。這些氣味會觸發大腦內部本能的情緒反應。

Our scent acts on a part of the canine brain associated with reward and the strongest reactions are produced by humans that pets know best, say scientists in America.

美國科學家聲稱，犬類的大腦中有一塊負責“獎勵”的區域，與寵物狗最親密的人身上的氣味能夠激起該區最強烈的反應。

Gregory Berns, of Emory University in Atlanta, said: ‘While we might expect that dogs should be highly tuned to the smell of other dogs, it seems that the “reward response” is reserved for their humans.

埃默裏大學的格里高利· 伯恩斯(Gregory Berns)説：“我們原以為這種反應是適用於狗之間的。目前看來這種‘獎勵反應’只適用於狗的主人。”

'When humans smell the perfume or cologne of someone they love, they may have an immediate, emotional reaction that's not necessarily cognitive.

“當人們嗅到愛人身上的香水或古龍水時，會立刻出現情緒上的反應，這種反應並不一定能被察覺到。”

'Our experiment may be showing the same process in dogs. But since dogs are so much more olfactory than humans, their responses would likely be even more powerful than the ones we might have.

“我們的實驗或許可以表明，狗對氣味的應激過程是相同的。不過鑑於狗的嗅覺比人類靈敏，因此它們對於氣味的反應會比人類強烈得多。”

'It's one thing when you come home and your dog sees you and jumps on you and licks you and knows that good things are about to happen.

“當你回到家時，你的狗一見到你就會撲到你懷裏，不停地舔你，它知道有好事要降臨了。”

'In our experiment, however, the scent donors were not physically present.

“但是在我們的實驗中，氣味樣本的源體（狗主人）並不在場。”

'That means the canine brain responses were being triggered by something distant in space and time. It shows that dogs' brains have these mental representations of us that persist when we're not there.'

“這意味着，犬類的大腦反應是由過去某處發生過的事所觸發的。同時也表明，當我們不在狗身邊的時候，我們的精神意識形態會留存在它們的大腦中。”

The university’s experiment - the first of its type - involved 12 dogs of various breeds who underwent brain scans while five different scents were placed in front of them.

埃默裏大學這項開拓性的實驗利用了十二隻不同品種的狗作為實驗對象，通過對這些狗的大腦進行掃描，來研究它們對五種氣味的反應有何不同。

The scent samples came from the subject itself, a dog the subject had never met, a dog that lived in the subject's household, a human the dog had never met, and a human that lived in the subject's household.

氣味樣本有五個來源，分別是：被測狗自己、被測狗從未見過的另一隻狗、居住在被測狗家中的另一隻狗、被測狗從未見過的一個人，以及被測狗的家人。

The familiar human scent samples were taken from someone else from the house other than the handlers during the experiment, so that none of the scent donors were physically present.

在實驗中，氣味樣本來自被測狗的家人，但他並不參與到實驗中來。因此，所有氣味樣本的源體都沒有出現在實驗現場。

The results showed that all five scents elicited a similar response in parts of the dogs' brains involved in detecting smells. Responses were significantly stronger for the scents of familiar humans, followed by that of familiar dogs.

實驗結果顯示，狗腦內負責嗅覺的區域對這五種氣味都產生了類似的反應。對於熟人的反應尤其強烈，對於熟悉的狗次之。

The findings, which were published in the journal Behavioural Processes, showed that dogs reacted strongest to the scent of a familiar human even when they were not there.

這項發現被刊登在《行為學過程》雜誌上，文中寫道，即使熟悉的人沒在狗身邊，他們的氣味也會激發狗最強烈的反應。

Pets trained as help or therapy dogs showed greater brain activity than the other dogs in the test.

在實驗中還發現，相比其他種類的狗而言，輔助犬和治療犬的大腦對氣味的反應更為明顯。

Researchers say the findings could improve the way animals who assist wounded veterans or disabled people are selected.

研究者聲稱，這些發現對於如何為受傷老兵和殘障人士選擇合適的輔助犬大有裨益。