neurodudes

When Will We Be Able to Build Brains Like Ours? – by Terry Sejnowski – scientificamerican.com

Terry Sejnowski discusses the recent ‘catfight’ that erupted between Dharmenda Modha of IBM and Henry Markram of the EPFL over claims from Modha that his group had successfully modeled the brain of a cat.

Dr. Sejnowski provides a summary of the quest to describe the nervous system using computational models and introduces a central question: What level of abstraction is appropriate?

“Looking at the same neuron, physicists and engineers tend to see the simplicity whereas biologists tend to see the complexity. The problem with simplified models is that they may be throwing away the baby with the bathwater. The problem with biophysical models is that the number of details is nearly infinite and much of it is unknown. How much brain function is lost by using simplified neurons and circuits?”

Despite the differing approaches, both Modha and Markram say we’ll have a model human brain by 2019. Sejnowski claims that these will be impoverished brain models, “at best these simulations will resemble a baby brain, or perhaps a psychotic one”, but he does remain hopeful in his closing remarks:

“And gradually, as it increasingly mimics the workings of our brains, the world around us will become smarter and more efficient. As this cognitive infrastructure evolves, it may someday even reach a point where it will rival our brains in power and sophistication. Intelligence will inherit the earth.”

Submitted By: Dan Knudsen

The Moral Life of Babies – NYTimes.com.

Paul Bloom talks about research on the morality of small children, and ways in which their morality is similar to and different from adults. Concise descriptions of supporting experiments is given throughout.

Basically, babies prefer nice people over mean people, but prefer people who punish mean people over people who reward mean people. But babies are not impartial; for example, they give favorable treatment to other babies who are wearing the same tee-shirt as themselves.

Also has some content about the cognition of babies in general. Experiments show that, at various young ages, “..babies think of objects largely as adults do, as connected masses that move as units, that are solid and subject to gravity and that move in continuous paths through space and time,” and “…expect people to move rationally in accordance with their beliefs and desires…”, and “…know that other people can have false beliefs”.

17th Joint Symposium on Neural Computation – UCLA
Saturday, May 22, 2010
9:00 am – 5:00 pm

Registration: $35 http://www.jsnc.caltech.edu/

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Want to run your research computations on Amazon’s cloud computing service?

http://aws.amazon.com/education/

No word as to when the next grant applicatiion deadline is, but it looks like an ongoing program.

Thanks to Brad Aimone, who got about $3000 worth of compute time for his research project, for alerting us to this.

When we learn new information we use only a tiny fraction of the neurons in our brain for that particular memory trace. In order to allow the molecular study of those specific neurons we combined elements of the tet system with a promoter that is activated by high level neural activity (the cfos promoter) to generate mice in which a genetic tag can be introduced into neurons that are active at a given point in time. The tag can be maintained for a prolonged period, creating a precise record of the neural activity pattern at a specific point in time. Using fear conditioning we found that the same neurons activated during learning were reactivated when the animal recalled the fearful event. We also found that these neurons were no longer activated following memory extinction, consistent with the idea that extinction modifies a component of the original memory trace.

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Supplementary Figure 1: A schematic illustrating the main finding. Slow gamma is maximal on the descending portion of the theta wave, and fast gamma peaks near the trough. Slow gamma serves to synchronize CA1 with inputs arriving from CA3, and fast gamma synchronizes CA1 with MEC input.

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http://mloss.org/software/

In addition to an index of over 200 open source machine learning software projects, the “about” section notes that there is an open source tools track of the journal JMLR, and that there are MLOSS workshops sometimes at NIPS and ICML.

Replay of behavioral sequences in the hippocampus during sharp wave ripple complexes (SWRs) provides a potential mechanism for memory consolidation and the learning of knowledge structures. Current hypotheses imply that replay should straightforwardly reflect recent experience. However, we find these hypotheses to be incompatible with the content of replay on a task with two distinct behavioral sequences (A and B). We observed forward and backward replay of B even when rats had been performing A for >10 min. Furthermore, replay of nonlocal sequence B occurred more often when B was infrequently experienced. Neither forward nor backward sequences preferentially represented highly experienced trajectories within a session. Additionally, we observed the construction of never-experienced novel-path sequences. These observations challenge the idea that sequence activation during SWRs is a simple replay of recent experience. Instead, replay reflected all physically available trajectories within the environment, suggesting a potential role in active learning and maintenance of the cognitive map.

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CNN News ran a segment last month on the meaning and impact of intelligence on a person’s life, as measured through a test such as the Wechsler Adult Intelligence Scale which gives an “IQ.” Dr. John Gabrieli of MIT displays brain scans that  show functional differences between brains of low IQ and high IQ subjects while completing intelligence tests in an MRI scanner. The higher IQ brain shows less activity than the lower IQ brain during the same task, indicating that smarter brains are more efficient.

The findings on IQ mentioned in the report are remarkable. The standing debate on the importance of IQ is also on display here. Researchers have found that 25% of what makes one successful can be attributed to IQ -but Dr. Gabrieli points to findings that increases in IQ are linked to “a better paying job, a healthy future, more stability in your family life.” This makes the prospect of “training intelligence” to increase IQ scores all the more alluring and relevant. A demonstration of a computer working memory task that is used to “train intelligence” is featured in the segment.

Watch the segment here:

http://cnn.com/video/?/video/health/2010/03/22/am.cho.intelligence.part1.cnn

Read more about the working memory task featured in the segment:

http://www.pnas.org/content/early/2008/04/25/0801268105.abstract

-A Neurodudes Reader

The statistics of shot durations in 150 films from 1935 to 2005 were analyzed. From about 1970 to the present, the power spectrum of shot durations in individual films has tended to become more like pink noise (power ~= 1/f). Also, autocorrelation shows that the lengths of nearby shots has become more and more correlated.

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