dijous, 25 d’octubre de 2012

Identifying the Brain's Own Facial Recognition System

The ability to recognize faces is so important in humans that the brain appears to have an area solely devoted to the task: the fusiform gyrus. Brain imaging studies consistently find that this region of the temporal lobe becomes active when people look at faces. Skeptics have countered, however, that these studies show only a correlation, but not proof, that activity in this area is essential for face recognition. Now, thanks to the willingness of an intrepid patient, a new study provides the first cause-and-effect evidence that neurons in this area help humans recognize faces—and only faces, not other body parts or objects.
Science Now // Elizabeth Norton // 23 October 2012

Well spotted. Two locations in the brain's fusiform gyrus respond to faces (red) but not to other objects (yellow). Credit: J. Parvizi et al., J. Neurosci, Advance Online Edition (2012)

An unusual collaboration between researchers and an epilepsy patient led to the discovery. Ron Blackwell, an engineer in Santa Clara, California, came to Stanford University in Palo Alto, California, in 2011 seeking better treatment for his epilepsy. He had suffered seizures since he was a teenager, and at age 47, his medication was becoming less effective. Stanford neurologist Josef Parvizi suggested some tests to locate the source of the seizures—and also suggested that it might be possible to eliminate the seizures by surgically destroying a tiny area of brain tissue where they occurred.

Parvizi used electrodes placed on Blackwell's scalp to trace the seizures to the temporal lobe, about an inch above Blackwell's right ear. Then, surgeons placed more electrodes on the surface of Blackwell's brain, near the suspect point of origin in the temporal lobe. Parvizi stimulated each electrode in turn with a mild current, trying to trigger Blackwell's seizure symptoms under safe conditions. "If we get those symptoms, we know that we are tickling the seizure node," he explains.

Certain electrodes, however, produced a dramatically different result from the colors and memories that Blackwell typically experienced. When Parvizi sent a signal through these electrodes on the fusiform gyrus, Blackwell told him, "You just turned into somebody else. Your whole face just sort of metamorphosed." When the stimulation was halted, Blackwell reported that Parvizi's face had "returned" to normal. The same test caused Blackwell to perceive unsettling distortion in the face of Parvizi's assistant. (See accompanying video.)

But the electrode stimulation affected only Blackwell's perception of faces of people he could see in person. Stimulating the two points also produced no change in Parvizi's suit, tie, or skin color, or in other objects around the room.

While the electrodes were in place, Parvizi got Blackwell's permission to turn the clinical probe into a research study, described online tomorrow in The Journal of Neuroscience. Teaming up with Stanford neuroscientist Kalanit Grill-Spector, who studies the brain areas important in facial recognition, he scanned Blackwell's brain using functional magnetic resonance imaging (fMRI) and confirmed that the two electrodes that influenced Blackwell's perception of faces were at points in the fusiform gyrus implicated by Grill-Spector's previous research. The researchers also recorded brain activity using the electrodes they'd placed on Blackwell's brain with a technique called electrocorticography. They found that the activity picked up by the electrodes at the two "hot spots" tracked with peak activity at these sites, as measured by fMRI.

Cognitive neuroscientist Juan R. Vidal of the Lyon Neuroscience Research Center in France applauds the authors' use of multiple methods and says the study is the first to prove that the fusiform gyrus plays a causal role in face perception. Previous studies only showed that the area is involved, Vidal says. "The complementary evidence of electrocorticography, fMRI, and brain stimulation will make it possible to study not only the effects of brain stimulation on the local neural networks that process face information, but also how they broadcast their information towards other regions in the brain."

Source: http://news.sciencemag.org/sciencenow/2012/10/identifying-the-brains-own-facia.html?rss=1

dimarts, 23 d’octubre de 2012

Link between creativity and mental illness confirmed

People in creative professions are treated more often for mental illness than the general population, there being a particularly salient connection between writing and schizophrenia. This according to researchers at Karolinska Institutet in Sweden, whose large-scale registry study is the most comprehensive ever in its field.

Last year, the team showed that artists and scientists were more common amongst families where bipolar disorder and schizophrenia is present, compared to the population at large. They subsequently expanded their study to many more psychiatric diagnoses – such as schizoaffective disorder, depression, anxiety syndrome, alcohol abuse, drug abuse, autism, ADHD, anorexia nervosa and suicide – and to include people in outpatient care rather than exclusively hospital patients.

The present study tracked almost 1.2 million patients and their relatives, identified down to second-cousin level. Since all were matched with healthy controls, the study incorporated much of the Swedish population from the most recent decades. All data was anonymized and cannot be linked to any individuals.

The results confirmed those of their previous study, that certain mental illness – bipolar disorder – is more prevalent in the entire group of people with artistic or scientific professions, such as dancers, researchers, photographers and authors. Authors also specifically were more common among most of the other psychiatric diseases (including schizophrenia, depression, anxiety syndrome and substance abuse) and were almost 50 per cent more likely to commit suicide than the general population.

Further, the researchers observed that creative professions were more common in the relatives of patients with schizophrenia, bipolar disorder, anorexia nervosa and, to some extent, autism. According to Simon Kyaga, Consultant in psychiatry and Doctoral Student at the Department of Medical Epidemiology and Biostatistics, the results give cause to reconsider approaches to mental illness.

"If one takes the view that certain phenomena associated with the patient's illness are beneficial, it opens the way for a new approach to treatment," he says. "In that case, the doctor and patient must come to an agreement on what is to be treated, and at what cost. In psychiatry and medicine generally there has been a tradition to see the disease in black-and-white terms and to endeavour to treat the patient by removing everything regarded as morbid."

Source: http://machineslikeus.com/news/link-between-creativity-and-mental-illness-confirmed

dimarts, 16 d’octubre de 2012

How diet affects brain functions

Studies released today explore the neurological component of dietary disorders, uncovering evidence that the brain's biological mechanisms may contribute to significant public health challenges — obesity, diabetes, binge eating, and the allure of the high-calorie meal. The findings were presented at Neuroscience 2012, the annual meeting of the Society for Neuroscience and the world's largest source of emerging news about brain science and health.

Machines Like Us

Scientists are ultimately searching for new ways to treat diet-related disorders while raising awareness that diet and obesity affect mental as well as physical health.

Today's new findings show that:
  • Being obese appears to affect cognitive function, requiring more effort to complete a complex decision-making task (Timothy Verstynen, PhD, abstract 802.20, see attached summary).
  • Brain images suggest that when people skip breakfast, the pleasure-seeking part of the brain is activated by pictures of high-calorie food. Skipping breakfast also appears to increase food consumption at lunch, possibly casting doubt on the use of fasting as an approach to diet control (Tony Goldstone, MD, PhD, abstract 798.02, see attached summary).
  • A study in rats suggests they may be able to curb binge-eating behavior with medication used to keep substance abusers clean and sober (Angelo Blasio, PhD, abstract 283.03, see attached summary).

Other recent findings discussed show that:
  • Amidst growing concern that diet-related metabolic disorders such as diabetes impair brain function, an animal study reports that a high-sugar diet may affect insulin receptors in the brain and dull spatial learning and memory skills. But omega-3 supplements may at least partially offset this effect (Rahul Agrawal, PhD, see attached summary).
  • Evidence from a rat study suggests that a new compound under development to treat compulsive eating disorders and obesity may be effective at blocking a specific receptor in the brain that triggers food cravings and eating when activated by "food related cues," such as pictures or smells, irrespective of the body's energy needs (Chiara Giuliano, PhD, see attached summary).
"These are fascinating studies because they show the brain is an often overlooked yet significant organ in an array of dietary disorders," said press conference moderator Paul Kenny, PhD, of The Scripps Research Institute in Florida, an expert on addiction and obesity. "Many of these findings have the potential to lead to new interventions that can help reduce the ranks of the obese, helping those who struggle daily with dietary decisions reassert control over what they eat."

dilluns, 1 d’octubre de 2012

Photo distance influences perception

Caltech study shows that the distance at which facial photos are taken influences perception.

Thursday, 27 September 2012 // by Katie Neith // Story Source // machineslikeus.com

[...] "It turns out that faces photographed quite close-up are geometrically warped, compared to photos taken at a larger distance," explains Bryan. "Of course, the close picture would also normally be larger, higher resolution and have different lighting—but we controlled for all of that in our study. What you're left with is a warping effect that is so subtle that nobody in our study actually noticed it. Nonetheless, it's a perceptual clue that influenced their judgments."

That subtle distance warping, however, had a big effect: close-up photos made people look less trustworthy, according to study participants. The close-up photo subjects were also judged to look less attractive and competent.[...]

Source: http://machineslikeus.com/news/photo-distance-influences-perception