Book review: 23 Problems in Systems Neuroscience

Where are the switches on this thing? : Nature

This new book looks interesting. Anyone read it? Here’s an excerpt from the Nature review:

David Hilbert, in his opening address at the International Congress of Mathematicians in Paris in 1900, presented his colleagues with 23 problems whose investigation he thought would provide the major advances in mathematics in the twentieth century. Although about half of the problems remain unsolved, history shows that mathematicians rose splendidly to the challenge.

Neuroscience has a rather briefer history than mathematics, but Leo van Hemmen and Terry Sejnowski felt that it was nonetheless mature enough for them to organize a meeting on ‘Problems in Neuroscience’ a century after Hilbert’s address. This printed version of their meeting, 23 Problems in Systems Neuroscience, has taken six years to arrive, but it is not too late and certainly not too little. In the place of one Hilbert are 40 problem-posers who have collectively contributed the 23 chapters, grouped into sections that sum up 5 current concerns: How have brains evolved? How is cerebral cortex organized? How do neurons interact? What can brains compute? How are cognitive systems organized? With such an attractive list of topics, this book is sure to find a wide audience at every level of interest, from lay readers to students and academics.

Neuroecon overview from Tyler Cowen

Enter the Neuro-Economists: Why Do Investors Do What They Do? – New York Times

A brief overview of the major researchers and research in neuroecon today.

I liked this part:

Are phrases like “nucleus accumbens” — referring to a subcortical nucleus of the brain associated with reward — welcome in a profession caught up in interest rates and money supply? Skeptics question whether neuro-economics explains real-world phenomena.

GABA in cosmetics to "freeze" skin

Take 10 Years Off My Face, in 60 Seconds – New York Times

Relevant details:

The company says the freezing effect comes from two ingredients: gamma aminobutyric acid, a substance found in the human nervous system that can block signals between nerves and muscles, and gynostemma pentaphyllum extract, derived from an herb used in traditional Chinese medicine. The company contends that gamma aminobutyric acid, a molecule that stays on the skin’s surface, activates smaller gynostemma molecules and sends them through the skin, where they signal muscles to relax, according to Gene Beilis, a pharmacist who is the vice president for product development at Freeze 24/7.

But the company has no scientific evidence to back up its claim that its products actually affect facial muscles.

And further down:

Mr. Beilis agreed that gamma aminobutyric acid is a powdery substance that coagulates when it dries, gripping the skin in place. Another ingredient in the product, eugenol, a clove derivative used in dentistry as an analgesic, “gives you a cool, numbing, tingling sensation,” he said.

SSRIs: Could anti-depressant action be mediated by the liver?

Platelet-Derived Serotonin Mediates Liver Regeneration — Lesurtel et al. 312 (5770): 104 — Science

Although it is not suggested by this paper (which was brought to my attention by F1000 biology), I’d like to suggest this as a very, very naive hypothesis: That some part of the anti-depressant effect of SSRIs could be mediated by their ability to promote liver regeneration, as the above Science article suggests. The paper itself details how 5HT-2A and 2B receptors are upregulated during regeneration and how 2A & 2B antagonists slow regeneration.

There is some evidence for a connection between liver disease and depression. (Also, traditional chinese medicine views depression as a disease of the liver.) Without a doubt, the liver plays a well-established role in general detoxification.

Although I have no evidence to suspect it, I think it would be interesting to see if the SSRIs were leading to increased liver serotonin, resulting in liver regeneration and hence less depression.

Forest for the trees?

On Making the Right Choice: The Deliberation-Without-Attention Effect — Dijksterhuis et al. 311 (5763): 1005 — Science

I don’t know quite what to make of this. In fact, I just don’t understand what is going on. But I can definitely think of examples from my own life where this is true. Sometimes not thinking about a problem really does lead to its solution and it’s fascinating to think about why this may be.

Also, the authors draw a connection between what they call unconscious thought (as performed in their experiments) and insights that can come “after sleeping on it”; I’m not sure these phenomena are the same. I think sleep taps into deeper organization processes that are not available on the timescale of unconscious thought, as given in the experiment.


Contrary to conventional wisdom, it is not always advantageous to engage in thorough conscious deliberation before choosing. On the basis of recent insights into the characteristics of conscious and unconscious thought, we tested the hypothesis that simple choices (such as between different towels or different sets of oven mitts) indeed produce better results after conscious thought, but that choices in complex matters (such as between different houses or different cars) should be left to unconscious thought. Named the “deliberation-without-attention” hypothesis, it was confirmed in four studies on consumer choice, both in the laboratory as well as among actual shoppers, that purchases of complex products were viewed more favorably when decisions had been made in the absence of attentive deliberation.

Is the Twinkie Defense for Real?

Does Eating Salmon Lower the Murder Rate? – New York Times

Neat stuff on the role nutrition can play in brain function… it surprises me that the effect can be so large.

Most prisons are notorious for the quality of their cuisine (pretty poor) and the behavior of their residents (pretty violent). They are therefore ideal locations to test a novel hypothesis: that violent aggression is largely a product of poor nutrition. Toward that end, researchers are studying whether inmates become less violent when put on a diet rich in vitamins and in the fatty acids found in seafood.

Proof That Neurons Communicate In Analog And Digital Simultaneously

The lab of David McCormick at Yale has released a paper that shows neurons operating in both analog and digital modes simultaneously.

From an article about the finding:

“McCormick’s group demonstrated that the analog signal present in the cell body also propagates down the axon and influences synaptic transmission onto other neurons. As the voltage on the sending cell becomes more positive, the amplitude of the subsequent transmission to the receiving cell, mediated by an action potential, is enhanced. This means that the waveform generated in the receiving neuron is not just determined by the digital pattern of action potentials generated, but also by the analog waveform occurring in the sending neuron.”

McCormick is a big name in the field. Is it time to start creating a new field of artificial neural networks that has both analog and digital modes?

Redwood Theoretical Neuroscience Videos Online

Last year, the Redwood Center for Theoretical Neuroscience moved from the Redwood Neuroscience Institute in Meno Park to the Helen Wills Neuroscience Institute at Berkeley. In October they held a symposium with several interesting speakers presenting on various topics within Theoretical Neuroscience.

The videos are now online for your perusal, or you can buy a DVD of the whole symposium for a paltry $5.

  • Horace Barlow, Cambridge University: The Roles of Theory, Commonsense, and Guesswork in Neuroscience
  • Dan Kersten, University of Minnesota: Human Object Perception: Theory, Psychophysics & Imaging
  • Sue Becker, McMaster University: The role of the hippocampus in memory, contextual gating, stress and depression
  • Florentin Worgotter, University of Goettingen: Learning in Neurons and Robots
  • Panel Discussion: The Role and Future Prospects for Math/Computational Theories in Neuroscience
  • David Heeger, New York University: What fMRI Can Tell Us about How Visual Cortex Works
  • Kevan Martin, ETH/UNI Zurich: Canonical Circuits for Neocortex
  • Terry Sejnowski, Salk Institute: Dendritic Darwinism
  • Jeff Hawkins, Numenta: Prospects and Problems of Cortical Theory

General Object And Face Classification Model in Neuron

In an impressive integrative effort, a new article in this month’s issue of Neuron describes a robust object and face classification model that is consistent with both behavioral and fMRI experiments.

From a preview of the article:

“A central theme that has emerged in research on face perception therefore is whether or not faces are “special” such that the cognitive and neural mechanisms that underlie their processing are different from those underlying the processing of other visual objects. […] In this issue of Neuron, Jiang et al. (2006) provide a compelling array of evidence supporting the idea that the processing of faces and objects do not rely on qualitatively different mechanisms. In a series of experiments, Jiang et al. present and integrate findings from neural modeling, behavior, and fMRI, showing that face classification, similarly to object classification, can be achieved by a simple-to-complex architecture, based on hierarchical shape detectors. Furthermore, variations of this model can account for both configural and feature-based processing without qualitative modification of the model’s structure.”

The Riesenhuber lab, from which this work comes, has been working on object recognition in an integrative way. The lab is particularly “at the intersection of neuroscience and AI”.