We describe a patient with persistent cerebral achromatopsia occurring after bilateral occipital strokes. Blinded color recognition was assessed with a computerized experimental paradigm and the patient reported the degree of confidence in the response exactness on a visual percent scale. Color recognition was accurate and above chance (Fisher’s exact test, p < 0.002). The degree of confidence in the answers showed a significant correlation with recognition scores (Spearman rank order correlation, p < 0.0001). These findings constitute the exceptional condition of what we called color anopsognosia (not knowing of seeing colors) and recall the theoretic figure of the ‘philosophical zombie’. However, the cognitive mechanisms of the dissociation between a subjective colorless vision and good performance for color naming still remain poorly understood.
Reading Hidden Intentions in the Human Brain
John-Dylan Haynes et el
Reading Hidden Intentions in the Human Brain, Current Biology
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.
I am somewhat doubtful whether this project will succeed, but let’s wait and see what it can do …
PORTLAND, Ore. — Passing the Turing test–the holy grail of artificial intelligence (AI), whereby a human conversing with a computer can’t tell it’s not human–may now be possible in a limited way with the world’s fastest supercomputer (IBM’s Blue Gene), according to AI experts at Rensselaer Polytechnic Institute. RPI is aiming to pass AI’s final exam this fall, by pairing the most powerful university-based supercomputing system in the world with a new multimedia group designing a holodeck, a la Star Trek.
Ciguatera often appears in Hong Kong news, with people getting poisoned by eating coral fish such as grouper. What is not reported is the surprising fact that in some cases this makes hot things feel cold and cold things feel hot. A nice example of qualia inversion!
Fish Poison makes Hot Things Feel Icy and Cold Things Feel Burning Hot
By Aaron Rowe
October 11, 2007
Grouper Eating some bad fish might not seem like the most spectacular way to ruin a tropical vacation, but for a 45-year-old man from England, a bit of tainted seafood was the beginning of a wild ride.
Cold water felt burning hot. Hot things felt icy cold. His tongue felt strange. Drinking alcohol or coffee only increased his suffering.
The patient had ciguatera poisoning — an ailment caused by ciguatoxin, a neurotoxin that is produced by microorganisms and found in a wide variety of tropical fish.
Using virtual-reality goggles, a camera and a stick, scientists have induced out-of-body experiences — the sensation of drifting outside of ne’s own body — in ordinary, healthy people, according to studies being published today in the journal Science. When people gazed at an illusory image of themselves through the goggles and were prodded in just the right way with the stick, they felt as if they had left their bodies.
The out-of-body experiments were conducted by two research groups using slightly different methods intended to expand the so-called rubber hand illusion.
In Switzerland, Dr. Olaf Blanke, a neuroscientist at the École Polytechnique Fédérale in Lausanne, asked people to don virtual-reality goggles while standing in an empty room. A camera projected an image of each person taken from the back and displayed that image as if it were six feet in front of the subject, who thus saw an illusory image of himself. Then Dr. Blanke stroked each person’s back for one minute with a stick while simultaneously projecting the image of the stick onto the illusory body. When the strokes were synchronous, people reported the sensation of being momentarily within the illusory body. When the strokes were not synchronous, the illusion did not occur.
In another variation, Dr. Blanke projected a “rubber body” — a cheap mannequin bought on eBay and dressed in the same clothes as the subject — into the virtual-reality goggles. With synchronous strokes of the stick, people’s sense of self drifted into the mannequin.
A separate set of experiments was carried out by Henrik Ehrsson, an assistant professor of neuroscience at the Karolinska Institute in Stockholm.
reports a case of dissociative fugue.
Dissociative fugue is a disorder in which one or more episodes of sudden, unexpected, and purposeful travel from home (fugue) occur, during which a person cannot remember some or all of his past life.
Neuron, Vol 50, 329-339, 20 April 2006
Goldberg et. el. argue that perceptual awareness seems not to engage areas associated with introspection. Problem for higher-order theories of consciousness?
Abstract: A common theme in theories of subjective awareness poses a self-related
“observer” function, or a homunculus, as a critical element without
which awareness can not emerge. Here, we examined this question using
fMRI. In our study, we compared brain activity patterns produced by a
demanding sensory categorization paradigm to those engaged during
self-reflective introspection, using similar sensory stimuli. Our
results show a complete segregation between the two patterns of
activity. Furthermore, regions that showed enhanced activity during
introspection underwent a robust inhibition during the demanding
perceptual task. The results support the notion that self-related
processes are not necessarily engaged during sensory perception and can
be actually suppressed.
Science 8 September 2006
Vol. 313. no. 5792, p. 1402
Detecting Awareness in the Vegetative State
Adrian M. Owen et. el
We used functional magnetic resonance imaging to demonstrate preserved conscious awareness in a patient fulfilling the criteria for a diagnosis of vegetative state. When asked to imagine playing tennis or moving around her home, the patient activated predicted cortical areas in a manner indistinguishable from that of healthy volunteers.