- Email: [email protected]
That tingling feeling
THE LAST WORD
Last words past and present, plus questions, at last-word.com
Blind as a cat
n A cat’s whiskers are regarded as tactile hairs or vibrissae. As a rule of thumb, their tips extend out to span a distance equal to the width of the cat’s body. With their extreme sensitivity, these whiskers aid the feline in spatial awareness. Vibrissae are primarily found on the face, although they do grow elsewhere on the cat’s body – predominantly on the forelegs, with a few on the abdomen. People with a sensory impairment commonly compensate by developing enhanced abilities in their other senses – blind people sometimes have better hearing than sighted people, for example. This phenomenon exists in many animals, too. In 1995, Josef Rauschecker described an example in a study of cats that had been visually deprived from birth. He discovered that auditory and somatosensory – touch-related – inputs dominated the anterior ectosylvian cortex, a brain region that normally processes visual signals (Trends in Neurosciences, vol 18, p 36). Interestingly, Rauschecker found that these cats had enlarged facial vibrissae, and in turn their brain’s somatosensory cortex differed from those in cats that could see. Rauschecker concluded that motor feedback had helped
My son took in a blind kitten four years ago. The cat now has extraordinarily long whiskers and eyebrows. She also has long hairs from the ears and scattered long ones over her body. The whiskers approach 60 millimetres and appear to be sensory compensation for sight loss. Is this likely, and how does it work?
n I cannot compare the cat in question with any of its siblings, so this response is speculative to some extent. The hair and whiskers of cats do vary dramatically, whether or not the animals can see. Cats have straight, non-woolly guard hairs that are extremely sensitive, especially at points such as the tips of their ears. Whiskers on the cat’s muzzle and wrists, and the ones forming its “eyebrows”,
“Whatever stimulates growth of nerves at the roots of hairs might also stimulate the follicles” are even more sensitive. Their stiffness has the effect of extending the cat’s reach and lends precision in assessing the position and texture of anything that they touch. Not surprisingly, the root of each hair has its own touchsensitive nerve supply. Around a whisker follicle, the nerve tissue is exceptionally dense. As a rule, sensory tissue atrophies if it receives little
Questions and answers should be concise. We reserve the right to edit items for clarity and style. Include a daytime telephone number and email address if you have one. Restrict questions to scientific enquiries about everyday phenomena. The writers of published answers will receive a cheque for £25 (or US$ equivalent). Reed Business Information Ltd reserves all rights to reuse question and answer material submitted by readers in any medium or format.
stimulation, but grows and becomes more complex if regularly stimulated by both the central nervous system and the environment. Nerve fibres and the capillaries that supply them with blood tend to grow practically in unison. What’s more, increased blood supply and associated hormonal stimuli promote tissue growth. It is therefore plausible that whatever growth factors stimulate nerve development at the roots of tactile hairs in a blind cat might also stimulate both the activity and vigour of the follicles. “With their extreme The result is long, infrequently sensitivity, whiskers shed sensory hairs and whiskers. aid the cat in matters Jon Richfield of spatial awareness” Somerset West, South Africa
New Scientist retains total editorial control over the content of The Last Word. Send questions and answers to The Last Word, New Scientist, Lacon House, 84 Theobald’s Road, London WC1X 8NS, UK, by email to [email protected] or visit www.last-word.com (please include a postal address in order to receive payment for answers). For a list of all unanswered questions send an SAE to LWQlist at the above address.
reorganise the processing of sensory stimuli. This would explain why the cat mentioned in the question has enlarged vibrissae. Jessica Harvey-Cox Colchester, Essex, UK
This week’s questions That tingling feeling
I was sitting in my tent, warming my legs with a fan heater, when my mum’s foot brushed my calf and I felt an electric sort of tingling in my leg. What could explain this? My dad felt the same sensation when he simply ran his finger over his calf, but when he greased his finger with butter and repeated the test, the feeling went away. He suggests that a certain amount of sticking when the finger is not greased causes a vibration, which the nerves detect. Could this be right? Patrick Nevill Nantwich, Cheshire, UK eco-friendly killing
Chainsaw sculptor Peter Bowsher has created a magnificent tree carving for us, depicting Edward Lear’s poem The Owl and the Pussycat (see photo). Now we need to kill off the tree without chopping it down. How can we do this with the least contamination of the surrounding environment? It is a lime (linden) tree, 3.6 metres tall and half a metre in diameter. Tom and Oonagh Gray Edinburgh, UK
Will we ever speak dolphin? The new book out now: packed full of wit, knowledge and extraordinary discovery Available from booksellers and at newscientist.com/dolphins
Last words past and present, plus questions, at last-word.com
Blind as a cat
n A cat’s whiskers are regarded as tactile hairs or vibrissae. As a rule of thumb, their tips extend out to span a distance equal to the width of the cat’s body. With their extreme sensitivity, these whiskers aid the feline in spatial awareness. Vibrissae are primarily found on the face, although they do grow elsewhere on the cat’s body – predominantly on the forelegs, with a few on the abdomen. People with a sensory impairment commonly compensate by developing enhanced abilities in their other senses – blind people sometimes have better hearing than sighted people, for example. This phenomenon exists in many animals, too. In 1995, Josef Rauschecker described an example in a study of cats that had been visually deprived from birth. He discovered that auditory and somatosensory – touch-related – inputs dominated the anterior ectosylvian cortex, a brain region that normally processes visual signals (Trends in Neurosciences, vol 18, p 36). Interestingly, Rauschecker found that these cats had enlarged facial vibrissae, and in turn their brain’s somatosensory cortex differed from those in cats that could see. Rauschecker concluded that motor feedback had helped
My son took in a blind kitten four years ago. The cat now has extraordinarily long whiskers and eyebrows. She also has long hairs from the ears and scattered long ones over her body. The whiskers approach 60 millimetres and appear to be sensory compensation for sight loss. Is this likely, and how does it work?
n I cannot compare the cat in question with any of its siblings, so this response is speculative to some extent. The hair and whiskers of cats do vary dramatically, whether or not the animals can see. Cats have straight, non-woolly guard hairs that are extremely sensitive, especially at points such as the tips of their ears. Whiskers on the cat’s muzzle and wrists, and the ones forming its “eyebrows”,
“Whatever stimulates growth of nerves at the roots of hairs might also stimulate the follicles” are even more sensitive. Their stiffness has the effect of extending the cat’s reach and lends precision in assessing the position and texture of anything that they touch. Not surprisingly, the root of each hair has its own touchsensitive nerve supply. Around a whisker follicle, the nerve tissue is exceptionally dense. As a rule, sensory tissue atrophies if it receives little
Questions and answers should be concise. We reserve the right to edit items for clarity and style. Include a daytime telephone number and email address if you have one. Restrict questions to scientific enquiries about everyday phenomena. The writers of published answers will receive a cheque for £25 (or US$ equivalent). Reed Business Information Ltd reserves all rights to reuse question and answer material submitted by readers in any medium or format.
stimulation, but grows and becomes more complex if regularly stimulated by both the central nervous system and the environment. Nerve fibres and the capillaries that supply them with blood tend to grow practically in unison. What’s more, increased blood supply and associated hormonal stimuli promote tissue growth. It is therefore plausible that whatever growth factors stimulate nerve development at the roots of tactile hairs in a blind cat might also stimulate both the activity and vigour of the follicles. “With their extreme The result is long, infrequently sensitivity, whiskers shed sensory hairs and whiskers. aid the cat in matters Jon Richfield of spatial awareness” Somerset West, South Africa
New Scientist retains total editorial control over the content of The Last Word. Send questions and answers to The Last Word, New Scientist, Lacon House, 84 Theobald’s Road, London WC1X 8NS, UK, by email to [email protected] or visit www.last-word.com (please include a postal address in order to receive payment for answers). For a list of all unanswered questions send an SAE to LWQlist at the above address.
reorganise the processing of sensory stimuli. This would explain why the cat mentioned in the question has enlarged vibrissae. Jessica Harvey-Cox Colchester, Essex, UK
This week’s questions That tingling feeling
I was sitting in my tent, warming my legs with a fan heater, when my mum’s foot brushed my calf and I felt an electric sort of tingling in my leg. What could explain this? My dad felt the same sensation when he simply ran his finger over his calf, but when he greased his finger with butter and repeated the test, the feeling went away. He suggests that a certain amount of sticking when the finger is not greased causes a vibration, which the nerves detect. Could this be right? Patrick Nevill Nantwich, Cheshire, UK eco-friendly killing
Chainsaw sculptor Peter Bowsher has created a magnificent tree carving for us, depicting Edward Lear’s poem The Owl and the Pussycat (see photo). Now we need to kill off the tree without chopping it down. How can we do this with the least contamination of the surrounding environment? It is a lime (linden) tree, 3.6 metres tall and half a metre in diameter. Tom and Oonagh Gray Edinburgh, UK
Will we ever speak dolphin? The new book out now: packed full of wit, knowledge and extraordinary discovery Available from booksellers and at newscientist.com/dolphins