neurodudes

This Is Your Brain Under Hypnosis - New York Times

Very interesting stuff. Subjects were hypnotized and told that days later they would see “gibberish” symbols printed in particular colors. They needed to report back the color that the word appeared in. (For those unfamiliar, the Stroop test presents color words, like “red”, in a different color, such as the word “red” written with green ink. People have difficulty reporting the color of the word because we have a strong need to “read” the written word.)

The highly hypnotizable subjects (grouped according to a predetermined measure) essentially showed no Stroop effect (ie. no reaction time difference with conflicting word and color). And, with fMRI, they saw that normally activated visual-reading areas were not activated in these subjects.

New genetically encoded fluorescent voltage-sensitive dye.

Sensitivity: up to 34% change (delta F/F) per 100 mV.
Time constant: .5 ms.
Phototoxicity: You can expose the cells to light for up to 100 seconds without much effect; over 200 seconds is noticably damaging.
Location: specific to cell membranes.
Not ratiometric (if you don’t know what that is, don’t worry about it).

Excerpt from figure caption: “(c) Confocal section of HEK293 cells expressing eGFP-F shows very little fluorescence from internal membranes. Scale bar, 20 mum. (d) Fluorescence response (shown as colored increments) of hVOS on voltage pulses from -120 to +120 mV in steps of 20 mV from a holding potential of 0 mV in patch-clamped HEK293 cells.”

Baron Chanda, Rikard Blunck, Leonardo C Faria, Felix E Schweizer, Istvan Mody and Francisco Bezanilla. A hybrid approach to measuring electrical activity in genetically specified neurons. Nature Neuroscience 8, 1619 - 1626 (2005)

Can Brain Scans See Depression? - New York Times

At first glance, this doesn’t seem like anything new (imaging-wise) to neuroscientists, but there are some interesting opinions in the article.

Interesting fact:

In a range of studies, researchers have found that people with schizophrenia suffer a progressive loss of their brain cells: a 20-year-old who develops the disorder, for example, might lose 5 percent to 10 percent of overall brain volume over the next decade, studies suggest.

And I like the way this guy thinks:

In an interview, Dr. Amen said that it was unconscionable that the profession of psychiatry was not making more use of brain scans. “Here we are, giving five or six different medications to children without even looking at the organ we’re changing,” he said.

But is this true?

“The thing for people to understand is that right now, the only thing imaging can tell you is whether you have a brain tumor,” or some other neurological damage, said Paul Root Wolpe, a professor of psychiatry and sociology at the University of Pennsylvania’s Center for Bioethics.

Does anyone know of any good work applying machine learning to doing discrimination of neural disease (like ADD, general depression, and anything that’s basically not a giant lesion/tumor) in imaging scans?