neurophilosophy | January 7, 2009Healthy aging is characterized by a gradual decline in cognitive function. Mental processes such as attention, memory and the ability to process information are at their peak when people are in their 30s and 40s, but as we get older, we find it increasingly difficult to focus on relevant information and to recall the names of familiar objects or people, and it takes us longer to perform mental tasks.
This age-related cognitive decline varies greatly between individuals. Some people experience little change or none at all, while others go on to develop Alzheimer's Disease or other forms of…
neurophilosophy | December 30, 2008Being so closely related to our own species, monkeys serve as important model organisms, and have provided many insights into the workings of the human brain. Research performed on monkeys in the past 30 years or so has, for example, been invaluable in the development of brain-machine interfaces.
Monkeys have also contributed a great deal to our understanding of the visual system - they were the subjects in many of the classic experiments of Hubel and Wiesel, which showed that the primary visual cortex contains neurons that are responsive to edges and bars moving in specific orientations.…
neurophilosophy | December 24, 2008Merry Christmas to all my readers. (Or rather Happy Holidays, as many of you, being in America, might say.)
This card is one of a set by Ernst Haeckel which, when expanded, became Kunstformen der Natur (Artforms in Nature), the masterpiece of biological illustration.
neurophilosophy | December 24, 2008Your face is a major component of your self-identity, but when you look into a mirror, how do you know that the person you are seeing is really you? Is it because the person in the reflection looks just like you? Or because the reflection moves when you move? Or perhaps because you see the face in the reflection being touched when you reach up to touch yours.
Recent studies have shown that recognizing our own bodies depends upon integrated information from the senses of vision, touch and proprioception (the sense of how our bodies are positioned in space). These cues can easily be…
neurophilosophy | December 23, 2008Synchiria is a neurological condition in which a stimulus applied to one side of the body is referred to both sides. If, for example, one's left hand is touched, he experiences tactile sensations on both hands. People with intact brains do not experience this, probably because of inhibitory mechanisms which prevent activity in one hemisphere of the brain from crossing over to the other.
This phenomenon is therefore very rare, and has only been reported in a small number of brain-damaged patients. It has been described in the auditory sense, whereby a person addresses a patient on the left…
neurophilosophy | December 23, 2008My second article for the Scientific American Mind Matters website is online now. This one is about the recent study which demonstrated that distorting the body image alters pain perception - specifically, it was found that using inverted binoculars to make the hand look smaller than it actually was led to a reduction in the pain and swelling induced by movement in patients with chronic pain.
It is not clear why this happens, but the findings obviously have major implications for pain management. One explanation put forward by the authors is that this simple manipulation caused the subjects…
neurophilosophy | December 22, 2008Spatial navigation is the process on which we rely to orient ourselves within the environment and to negotiate our way through it. Our ability to do so depends upon cognitive maps, mental representations of the surrounding spaces, which are constructed by the brain and are used by it to calculate one's present location, based on landmarks in the environment and on our movements within it, and to plan future movements.
The term "cognitive map" was first used in a landmark 1948 paper, in which the behavioural psychologist Edward Tolman described his now famous studies of rats in mazes. In…
neurophilosophy | December 16, 2008One of the bigger challenges facing researchers who are developing artificial limbs is to create prostheses that not only act but also feel like real limbs. This is especially true for the hand, which is one of the most sensitive parts of the human body, and although advanced prosthetic hands with fully articulated digits which move independently of one another are now available, they would be far more useful if they provided the user with sensory feedback.
Last year, surgeons from the Rehabilitation Center of Chicago made some progress towards this goal: they fitted amputee Claudia Mitchell…
neurophilosophy | December 14, 2008
These beautiful watercolour drawings of diseased brain sections come from a book called Reports on Medical Cases, Selected with a View to Illustrate the Symptoms and Cure of Diseases by a Reference to Morbid Anatomy, by Richard Bright.
Bright's book was published in 1827, but these illustrations appeared in a separate volume accompanying the second part of the work, which was published in 1831, and devoted to the pathology of the nervous system.
The complete work included approximately 300 plates. These illustrations are by Frederick Richard Say (1805-1860), a successful portrait…
neurophilosophy | December 14, 2008Professor Martha J. Farah emailed me recently to ask if I'd help spread the word about Neuroscience Boot Camp, which will take place at the University of Pennsylvania in August of next year:
What happens at Neuroscience Boot Camp?
Through a combination of lectures, break-out groups, panel discussions and laboratory visits, participants will gain an understanding of the methods of neuroscience and key findings on the cognitive and social-emotional functions of the brain, lifespan development and disorders of brain function.
Each lecture will be followed by extensive Q&A. Break-out…
neurophilosophy | December 12, 2008Recent advances in functional neuroimaging have enabled researchers to predict perceptual experiences with a high degree of accuracy. For example, it is possible to determine whether a subject is looking at a face or some other category of visual stimulus, such as a house. This is possible because we know that specific regions of the brain respond selectively to one type of stimulus but not another.
These studies have however been limited to small numbers of visual stimuli in specified categories, because they are based on prior knowledge of the neural activity associated with the conscious…
neurophilosophy | December 12, 2008Archaeologists have unearthed a 2,000-year-old skull containing what they believe to be the remains of a fossilized brain, while excavating a site at the University of York.
Rachel Cubitt, one of the researchers on the dig, felt something moving inside the skull and noticed "an unusual yellow substance" when she peered through an opening in its base.
Later on, a computed tomography (CT) scan performed by neurologists at York Hospital revealed that the skull contained a shrunken brain-shaped structure. Further analyses will now be carried out to establish whether the yellow substance is…
neurophilosophy | December 9, 2008The top medical breakthrough of the year, according to TIME Magazine, is the creation of motor neurons from ALS patients. (Here are all 50 of the magazine's Top 10 lists for 2008.)
This work was carried out by researchers at Harvard and Columbia universities, and published in the journal Science back in August. I wrote about it at the time: skin cells were taken from an 82-year-old ALS patient and made to de-differentiate into pluripotent stem cells, which were then reprogrammed to form motor neurons, the cell type which degenerates in ALS.
This research is significant for two reasons. First…
neurophilosophy | December 9, 2008In The Expression of the Emotions in Man and Animals, Charles Darwin noted that facial expressions vary little across cultures. We all recognize that someone whose eyes and mouth are wide open, and whose eyebrows are raised, is afraid. This characteristic expression is a social signal, which warns others of a potential threat and serves as a plea for help. It also enhances our ability to sense potential threats, by increasing the range of vision and enhancing the sense of smell.
Recognizing fear in others involves perceiving cues which we are consciously aware of as well as subliminal…
neurophilosophy | December 5, 2008The amnesic patient known as H.M., who is the best known case study in neuropsychology, has died, at the age of 82.
H.M., whose full name has now been revealed as Henry Gustav Molaison, lost completely the ability to form new memories following a radical surgical procedure to treat his severe and intractable epilepsy.
The operation was performed in 1953 by William Scoville, a neurosurgeon at Hartford Hospital in Connecticut. Using an experimental technique he had recently developed, Scoville removed both of H.M.'s hippocampi in their entirety, together with some of the surrounding structures…
neurophilosophy | December 2, 2008Body ownership - the sense that one's body belongs to one's self - is central to self-awareness, and yet is something that most of us take completely for granted. We experience our bodies as being an integral part of ourselves, without ever questioning how we know that our hands belong to us, or how we can distinguish our body from its surroundings.
These issues have long intrigued philosophers and psychologists, but had not been investigated by neuroscientists until recently. Now researchers from the Karolinska Institute report that they have induced a "body-swap" illusion, whereby…
neurophilosophy | December 1, 2008Synaesthesia is a neurological condition in which stimuli of one sensory modality evoke experiences in another modality. This is thought to occur as a result of insufficient "pruning" during development, so that most of the pathways connecting parts of the brain mediating the different senses remain in place instead of being eliminated. Consequently, there is too much cross-talk between sensory systems, such that activation of one sensory pathway leads simultaneously to activity in another.
Once believed to be extremely rare, synaesthesia is now thought to be relatively common. The cross-…
neurophilosophy | November 26, 2008The term body image was coined by the great neurologist Henry Head and refers to a mental representation of one's physical appearance. Constructed by the brain from past experience and present sensations, the body image is a fundamental aspect of both self-awareness and self-identity, and can be disrupted in many conditions.
Disruption of the body image can have profound physical and psychological effects. For example, body image distortion is implicated in eating disorders such as anorexia nervosa, and also leads to phenomena such as phantom limb syndrome and body dysmorphic disorder;…
neurophilosophy | November 25, 2008For most of us, visual perception is crucial for spatial navigation. We rely on vision to find our way around, to position ourselves and localize objects within the surroundings, and to plan our trajectory on the basis of the layout of the environment. Blind people would therefore seem to be at a disadvantage. Unable to rely on vision, they depend instead upon different sorts of cues to form their representations of space. They rely, for example, on proprioception, which provides a sense of the location, movement and posture of one's own body through space, and on vestibular information…
neurophilosophy | November 24, 2008Prosopagnosia is a neurological condition characterised by an inability to recognize faces. In the most extreme cases, the prosopagnosic patient cannot even recognize their own face in the mirror or a photograph, and in his 1985 book The Man Who Mistook His Wife For A Hat, the neurologist Oliver Sacks describes the extraordinary case of a farmer who lost the ability to recognize the faces of his cows!
Also known as face blindness, prosopagnosia is associated with damage to specific parts of the temporal lobes. But there are also documented cases of patients who have the condition in the…