neurodudes

This nytimes article describes an experiment in which

1) In front of chimps, human researchers demonstrate opening a box, but they throw in some unnecessary steps. The box is constructed so that an onlooker can figure out which steps are unnecessary just by watching. The chimps learn to open the box, but skip the unnecessary steps.
2) In front of human children, the researchers do the same thing. The children learn to open the box, but are careful to do exactly what the demonstrator did, including the unnecessary steps.

The children’s awareness of which steps were unnecessary in condition (4) is shown by having some children who do not get to see a demonstration of how to open the box. These children are able to figure out how to open it (without the unnecessary steps, of course).

Thus, human children, as compared to chimps, are more likely to imitate exactly what they see.

Victoria Horner, Andrew Whiten. Causal knowledge and imitation/emulation switching in chimpanzees (Pan troglodytes) and children (Homo sapiens), Animal Cognition, Volume 8, Issue 3, Jul 2005, Pages 164 – 181

This is really weird!

Somebody debunk this before it blows my mind.

–Stephen

Nerve Stimulation and Revenue Growth – New York Times

Some interesting tidbits about the backroom financial manueverings of some vagus nerve stimulator startups. Hadn’t heard of Advanced Neuromodulation Systems before.

From Eugene Izhikevich’s website (which by the way is full of cool stuff that we’ll probably post about someday):

“On October 27, 2005 I finished simulation of a model that has the size of the human brain. The model has 100,000,000,000 neurons (hundred billion or 10^11) and almost 1,000,000,000,000,000 (one quadrillion or 10^15) synapses. It represents 300×300 mm^2 of mammalian thalamo-cortical surface, specific, non-specific, and reticular thalamic nuclei, and spiking neurons with firing properties corresponding to those recorded in the mammalian brain. The model exhibited alpha and gamma rhythms, moving clusters of neurons in up- and down-states, and other interesting phenomena (watch a 25M .avi or .mov movie).

One second of simulation took 50 days on a beowulf cluster of 27
processors (3GHz each). Why did I do that?”

In this nice open-access (ie. free!) essay in October’s PLoS Biology, David Kleinfeld and Oliver Griesbeck describe the revolution in neural recording that is taking electrophysiology from the realm of dark-arts (lots of training) to simpler genetically-encoded, imaging-based techniques. A lot of ground is covered in the article, including the creation of many new colors of fluorescent proteins (XFPs) that can be genetically targeted and the tagging of the XFPs with Ca, voltage, and pH sensors. A nice summary table is included comparing the techniques too:

As you have likely noticed, Bayle and I post heavily about these new recording techniques because of our strong belief that a lot of neuroscience will be enabled by improving our ability to stimulate and record from entire networks of neurons with high resolution. Yesterday, I was listening to one of the many recent neuroscience talks here at MIT in which philosopher Pat Churchland suggested, as many others also have, that the problem of consciousness might be more of an artifact of primitive science than an actual scientific problem. She made a very nice analogy with a problem from centuries ago when scientists were unsure about the existence of life forces and what precisely made an animal alive. Of course, with modern cell biology, we now have a cellular theory of life, disease, and death. (To be fair, Churchland went on to say that people like Christof, Crick et al. are misguided in attempting to study neural correlates of consciousness. I completely disagree with that; at the very least, those scientists are helping to extend our understanding of the visual system and the difference between perception that we are aware of [conscious] and perception that has a neural correlate but that we are not aware of [unconscious]. Honestly, who cares if they say they’re studying consciousness or not — make a judgement based on the science.)

Google has opened a new service called Google Base that allows you to upload, publish and index arbitrary data for free. Does this mean that scientists can now share their raw data simply by uploading it to Google Base, without bothering to store and webhost it themselves?

I checked out the site and it seems that Google explicitly invites all kinds of data, with no size restrictions. But I find it hard to believe that Google can really handle all the terrabytes of data that some labs generate; in fact, just a few days ago, I was thinking of uploading a few hundred gigs of imaging videos to Google Video; but do they really want that? On the other hand, maybe they can handle it; they are Google, after all.

So my opinion is that scientists should start submitting their data (all of it, including large raw data files) to Google Base until/unless Google says they changed their mind and they don’t want it.

Also, don’t forget about subject-specific databases like neurodatabase.org; until the bright future of ubiquitous cross-database integration arrives, it will be easier to search for things with the subject-specific databases, provided that enough people use the same ones.

See this news article in Nature for more commentary.

A web page tracking work on the optical control of neural activity, “focusing on the applications of channelrhodopsin-2.”

Maintained by Edward Boyden (the first author on the September optical stimulation paper in Nature that we previously talked about).

I think we’re undergoing somewhat of a slow revolution in the cognitive sciences. The field is slowly coming to focus on the central role of prior expectation in cognition.

Evidence that prior expectation has a large effect on the interpretation of sensory input is by no means new, but it seems to me that people are focusing on prior expectation more and more when they theorize about the mind. For example:

* The recent post about hypnosis and the Stroop effect (the nytimes article focuses on this aspect of the work)
* The fact that most of the connections between lower-order sensory areas and higher-order areas are feedback connections from the higher to the lower
* The fact that imagining a visual image causes activation in (see [1], there’s a bunch of followup studies to that one too)
* This may be just a rumor, but I’ve heard that it’s been demonstrated that when you saccade, that near the end of the interim period when you cannot see, your primary visual cortical cells start firing in the patterns corresponding to what you expect to see at the new location. Does anyone have a source for that (I’ll ask the person who told me if they have a citation)?
* Jeff Hawkins’s effort to make theories of the mind centered on prediction
* The current fad in Bayesian analysis in theoretical cognitive science (which provides a mathematical framework for computing probabilities which take into account both prior expectation and evidence)

I don’t mean to imply that this potential paradigm shift is something that people are unaware of; indeed, Kosslyn, Hawkins and others have long been avid proponents of the view that sensory processing (as well as other aspects of cognition) is best understood as centered around prediction and prior expectation, not incoming sensory data.

[1] Kosslyn, S. M., Alpert, N. M., Thompson, W. L., Maljkovic, V., Weise, S. B., Chabris, C. F., Hamilton, S. E., Rauch, S. L., & Buonanno, F. S. (1993). Visual mental imagery activates topographically organized visual cortex: PET investigations. Journal of Cognitive Neuroscience, 5(3), 263–287.

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.

Timid Mice Made Daring by Removing One Gene – New York Times

Original article in Cell.