The Miller Lab @ MIT

  • Multiplexing Stimulus Information through Rate and Temporal Codes in Primate Somatosensory Cortex

    Miller Lab

    Two different features of a vibrotactile stimulus are encoded by rate and temporal codes in primary sensory cortex.  The amplitude was reflected in the overall firing rate of neurons whereas the frequency was reflected in the oscillatory phase-locking of spikes.
    Harvey et al, 2013 PLOS Biology

    The two coding schemes, rate vs temporal codes, are often debated as if they are in opposition and mutually exclusive.  They are not and this paper elegantly demonstrates this important point.  And this is not just limited to vibratory tactile stimuli.  Schroeder and colleagues have argued that all sensory processing involves periodic sampling and rhythmic entrainment of cortical neurons.  (We, for example, periodically sample vision via periodic eye movements and shifts of attention.)

    Plus, rhythmic synchrony allows multiplexing, not only by adding another coding dimension as shown here, but also by allowing neurons to communicate different messages to different targets depending on whom they are synchronized with (and how, e.g., phase, frequency).  That way, the same neurons can participate in different functions yet still convey unambiguous messages.  For a brief discussion of this latter point and why we need multiplexing in the cortex see: Miller, E.K. and Fusi, S. (2013) Limber neurons for a nimble mind. Neuron. 78:211-213. View PDF

  • Cerebellum and Cognition: Evidence for the Encoding of Higher Order Rules

    Miller Lab
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    This paper reports FMRI in humans performing a task requiring first-order rules (S-R associations with a specific motor output) and second order rules that govern the use of the first-order rules.  Cerebellum lobules that project to the prefrontal cortex show activation for both types of rules.  This suggests that the cerebellum contributes to rule-based behaviors even when the rules are higher-order and don’t directly involve a motor command.
    http://cercor.oxfordjournals.org/content/23/6/1433.abstract

    For further reading on the role of rules in cognition and their neural implementation see:
    Miller, E.K. and Cohen, J.D. (2001) An integrative theory of prefrontal cortex function. Annual Review of Neuroscience, 24:167-202.  View PDF »

    Buschman, T.J., Denovellis, E.L., Diogo, C., Bullock, D. and Miller, E.K. (2012) Synchronous oscillatory neural ensembles for rules in the prefrontal cortex. Neuron, 76: 838-846.  View PDF

    Wallis, J.D., Anderson, K.C., and Miller, E.K. (2001) Single neurons in the prefrontal cortex encode abstract rules. Nature, 411:953-956. View PDF »

  • El Pais: Boston, another Silicon Valley

    Miller Lab
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    Miller Lab Research Scientist Vicky Puig quoted in a article in El Pais.  The Picower Institute at MIT is called  “one of the best neuroscience centers in the world”.  One of the?

    In Spanish, but that’s why we have Google Translate.
    http://elpais.com/elpais/2013/05/01/eps/1367419412_106866.html

  • Henry Molaison: the amnesiac we’ll never forget. The Guardian reviews Sue Corkin’s new book.

    Miller Lab

    When an operation left Henry Molaison unable to form new memories, he became the most important patient in the history of brain science. Neurologist Suzanne Corkin reveals what it was like to work with ‘HM’ for 46 years

    http://www.guardian.co.uk/science/2013/may/05/henry-molaison-amnesiac-corkin-book-feature?CMP=twt_gu

  • WSJ: How the Brain Really Works. (It’s not a phrenology map)

    Miller Lab
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    A nice article in the Wall Street Journal describing Jack Gallant’s recent FMRI work.  They didn’t just  subtract conditions and come up with a typical imaging map with one or a few isolated bits of activation.  Jack L. Gallant, Tolga Çukur and colleagues used sophisticated  analyses to find the relationship between the patterns of whole brain activity and the content of videos watched by the subjects.  This revealed wide networks, not isolated patches, of neurons engaged by attention to different things in the video (humans vs vehicles, etc).

    It also showed how dynamic and flexible the brain is.  When subjects looked for humans, large portions of the cortex were sensitive to humans and less sensitive to vehicles. When subjects looked for vehicles, large portions of the cortex became vehicle detectors.  Many of the same brain areas were involved in multiple networks, changing when people changed the focus of their attention.  Thus, rather than the cortex being composed of modules with strict specializations, high-level information is spread across wide-ranging cortical networks of neurons that participate in many different functions, adapting their properties to current cognitive demands.

    We have long argued that mixed selectivity, adaptive coding neurons are crucial for hallmarks of cognition like flexibility.  And in forthcoming paper (Rigotti et al), we show computationally that you can’t build a complex brain w/o them.

    For a brief discussion of this issue, read this Preview of a paper by Stokes et al:
    Miller, E.K. and Fusi, S. (2013) Limber neurons for a nimble mind. Neuron. 78:211-213. View PDF

    And stay tuned for this paper:
    Rigotti, M., Barak, O., Warden, M.R., Wang, X., Daw, N.D., Miller, E.K., & Fusi, S. (in press) The importance of mixed selectivity in complex cognitive tasks. Nature.

  • Witnesses 1,200 Miles Apart Describe Same Giant Triangle UFO – Let’s run it through the BS detector

    Miller Lab

    Two people describe the same shape in the sky 2 hours and 2 time zones apart.  Thy must have seen the same real thing, right?  Maybe, but maybe not.
    http://www.huffingtonpost.com/roger-marsh/witnesses-1200-miles-apart_b_3179709.html

    This could just be a coincidence driven by large numbers.  Millions of people view the sky every night over thousands of moments, night after night.  That is a huge number of observations.   People report all sorts of weird stuff in the sky.  The chance that  two people happen  to think  they see the same thing on the same night in a timely fashion has a very low probability.  But with so many observations of the sky, night after night, that low probability can nonetheless result in real numbers.  Note that there are only two isolated witnesses.  It wasn’t like a crowd of 100 saw each manifestation.

    I always say: It would be weird if coincidences never happened.

  • A debate on the utility of Granger causality

    Miller Lab

    Granger causality is designed to measure effect, not mechanim.
    http://www.frontiersin.org/Neuroinformatics/10.3389/fninf.2013.00006/full

  • Ventral Hippocampal Neurons Are Shaped by Experience to Represent Behaviorally Relevant Contexts

    Miller Lab

    Eichenbaum and crew show that neurons in different parts of the CA3 area of the rat hippocampus acquire different memories at different levels.  More specific memories are rapidly acquired by  dorsal CA3 whereas the ventral CA3 neurons more gradually accumulate information across training episodes to form broader, more generalized context representations.
    http://www.jneurosci.org/content/33/18/8079.abstract

    The interplay between brain systems that rapidly acquire specific information and systems that more slowly build generalizations may be a common theme of brain function (Seger and Miller, 2010).  We have suggested a similar relationship between the basal ganglia and frontal cortex for goal directed learning. Think of it as the basal ganglia learning the pieces of a puzzle and the prefrontal cortex gradually putting the puzzle together (Miller and Buschman, 2007).

    The idea is that rapid plasticity in the basal ganglia learns simple, specific things very quickly. The output of the basal ganglia repeatedly “trains” slower plasticity in the frontal cortex (Pasupathy and Miller, 2005).  In this way, the frontal cortex  gradually forms abstractions from the common structure in the information fed to it by the basal ganglia.  We have seen direct evidence for this during category learning (Antzoulatos and Miller, 2011).  Early in learning, when animals try to solve the task by learning about each specific exemplar,  basal ganglia neurons lead the charge.  Then, when the number of exemplars becomes overwhelming and the animals finally start abstracting the categories, the prefrontal cortex takes over.

    For further reading see:
    Antzoulatos,E.G. and Miller, E.K. (2011) Differences between neural activity in prefrontal cortex and striatum during learning of novel, abstract categories. Neuron. 71(2): 243-249. View PDF »

    Seger, C.A. and Miller, E.K. (2010) Category learning in the brain. Annual Review of Neuroscience, Vol. 33: 203-219. View PDF »

    Miller, E.K. and Buschman, T.J. (2007)  Rules through recursion: How interactions between the frontal cortex and basal ganglia may build abstract, complex, rules from concrete, simple, ones. In: The Neuroscience of Rule-Guided Behavior, S. Bunge & J. Wallis (eds.), Oxford University Press. View PDF »

    Pasupathy, A. and Miller, E.K. (2005) Different time courses for learning-related activity in the prefrontal cortex and striatum. Nature, 433:873-876. View PDF »

  • NY Times – Daniel Dennett: Philosophy That Stirs the Waters

    Miller Lab

    Clinging to the idea that the mind is more than just the brain, Mr. Dennett said, is “profoundly naïve and anti-scientific.”

    Yep.

    http://www.nytimes.com/2013/04/30/books/daniel-dennett-author-of-intuition-pumps-and-other-tools-for-thinking.html?smid=tw-share&_r=0

  • NY Times PROFILES IN SCIENCE: Right Time and Place (Edvard and May-Britt Moser)

    Miller Lab

    Great people doing great science.

    NY Times April 29, 2013 TRONDHEIM, Norway — In 1988, two determined psychology students sat in the office of an internationally renowned neuroscientist in Oslo and explained to him why they had to study with him….
    Read it here: http://www.nytimes.com/2013/04/30/science/may-britt-and-edvard-moser-explore-the-brains-gps.html?hp