Nature Neuroscience 11, 772 – 779 (2008)
Published online: 22 June 2008 | doi:10.1038/nn.2143
Pungent agents from Szechuan peppers excite sensory neurons by inhibiting two-pore potassium channels
Diana M Bautista1,2,3,4, Yaron M Sigal1,2,4, Aaron D Milstein2, Jennifer L Garrison2,3, Julie A Zorn2, Pamela R Tsuruda1,2,3, Roger A Nicoll1,2 & David Julius1,2
In traditional folk medicine, Xanthoxylum plants are referred to as ‘toothache trees’ because their anesthetic or counter-irritant properties render them useful in the treatment of pain. Psychophysical studies have identified hydroxy-alpha-sanshool as the compound most responsible for the unique tingling and buzzing sensations produced by Szechuan peppercorns or other Xanthoxylum preparations. Although it is generally agreed that sanshool elicits its effects by activating somatosensory neurons, the underlying cellular and molecular mechanisms remain a matter of debate. Here we show that hydroxy-alpha-sanshool excites two types of sensory neurons, including small-diameter unmyelinated cells that respond to capsaicin (but not mustard oil) as well as large-diameter myelinated neurons that express the neurotrophin receptor TrkC. We found that hydroxy-alpha-sanshool excites neurons through a unique mechanism involving inhibition of pH- and anesthetic-sensitive two-pore potassium channels (KCNK3, KCNK9 and KCNK18), providing a framework for understanding the unique and complex psychophysical sensations associated with the Szechuan pepper experience.
More Brain Research Suggests ‘Use It Or Lose It’
ScienceDaily (Feb. 12, 2008) — Queensland Brain Institute (QBI) scientists have found another important clue to why nerve cells die in neurodegenerative diseases, based on studies of the developing brain.
Neuroscientists at The University of Queensland have just published findings, which add more weight to the “use it or lose it” model for brain function.
QBI’s Dr Elizabeth Coulson said a baby’s brain generates roughly double the number of nerve cells it needs to function; with those cells that receive both chemical and electrical stimuli surviving, and the remaining cells dying.
Media depictions of violence, although often claimed to induce viewer aggression, have not been shown to affect the cortical networks that regulate behavior.
Using functional magnetic resonance imaging (fMRI), we found that repeated exposure to violent media, but not to other equally arousing media, led to both diminished response in right lateral orbitofrontal cortex (right ltOFC) and a decrease in right ltOFC-amygdala interaction. Reduced function in this network has been previously associated with decreased control over a variety of behaviors, including reactive aggression. Indeed, we found reduced right ltOFC responses to be characteristic of those subjects that reported greater tendencies toward reactive aggression. Furthermore, the violence-induced reduction in right ltOFC response coincided with increased throughput to behavior planning regions.
These novel findings establish that even short-term exposure to violent media can result in diminished responsiveness of a network associated with behaviors such as reactive aggression.
Wadsworth Center scientists have succeeded in developing a BCI that provided people who are severely disabled with the ability to use their personal computers. For example, they were able to word-process, send e-mail messages, and remotely turn on or off the lights or TV in their homes. A laptop computer and cap allow for portability and ease of use.
Brain’s ‘addiction centre’
The discovery of individuals with brain damage who give up smoking with ease could point the way to a surgical ‘cure’ for smoking, US scientists say. The particular brain area damaged – called the insula – appears to be central to the urge to smoke, a team told the journal Science.
The insula receives information from other parts of the body and is thought to help translate those signals into something that is subjectively felt, such as hunger, pain, or a craving. Dr Bechara’s team studied 69 brain-damaged smokers – 19 who had suffered insula injury.
A man with an unusually tiny brain managed to live an entirely normal life despite his condition, caused by a fluid buildup in his skull, French researchers reported on Thursday.
Scans of the 44-year-old man’s brain showed that a huge fluid-filled chamber called a ventricle took up most of the room in his skull, leaving little more than a thin sheet of actual brain tissue.
“He was a married father of two children, and worked as a civil servant,” Dr. Lionel Feuillet and colleagues at the Universite de la Mediterranee in Marseille wrote in a letter to the Lancet medical journal.
Spindle neurons discovered in humpback whales. Only seen only in humans, the great apes, and other cetaceans such as dolphins. The finding may help explain some of the behaviors seen in whales, such as intricate communication skills, the formation of alliances, cooperation, cultural transmission and tool usage, the researchers report in The Anatomical Record. (Patrick Hof and Estel Van der Gucht of the Department of Neuroscience at Mount Sinai School of Medicine in New York)
Nature Neuroscience – 9, 1177 – 1185 (2006) Published online: 6 August 2006; | doi:10.1038/nn1745Kalanit Grill-Spector et. el.
Higher resolution fMRI shows that FFA has a heterogeneous structure: localized subregions within the FFA highly selective to faces are spatially interdigitated with localized subregions highly selective to different object categories. We found a preponderance of face-selective responses in the FFA, but no difference in selectivity to faces compared to nonfaces. Thus, standard fMRI of the FFA reflects averaging of heterogeneous highly selective neural populations of differing sizes, rather than higher selectivity to faces. These results suggest that visual processing in this region is not exclusive to faces.
“US firm Microvision has developed a system that projects lasers onto the retina, allowing users to view images on top of their normal field of vision.It could allow surgeons to get a bird’s eye view of the innards of a patient, offer military units in the field a view of the entire battlefield and provide mechanics with a simulation of the inside of a car’s engine.
The system uses tiny lasers, which scan their light onto the retina to produce the entire range of human vision, reported the journal of the Institute of the Electrical and Electronics Engineers, IEEE Spectrum.”
Nov 2005A few years ago scientists managed to wire a monkey’s brain to a robotic arm. The monkey learned to manipulate the arm simply by thinking. This year, John Donoghue at Brown University has managed to do the same – with a human.
Matthew Nagel, a C4 paralytic – from the neck down – has been playing pong, drawing circles and manipulating a computer with thoughts alone via the BrainGate. This technology promises to have profound changes on the lives of millions of paralyzed and handicapped individuals, but implications run much deeper and may one day affect us all.