The Miller Lab

  • How Brain Waves Guide Memory Formation

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    MIT News Office: Neurons hum at different frequencies to tell the brain which memories it should store.
    New discovery from the Miller Lab

    Anne Trafton | MIT News Office
    February 23, 2015
    Our brains generate a constant hum of activity: As neurons fire, they produce brain waves that oscillate at different frequencies. Long thought to be merely a byproduct of neuron activity, recent studies suggest that these waves may play a critical role in communication between different parts of the brain.

    A new study from MIT neuroscientists adds to that evidence. The researchers found that two brain regions that are key to learning — the hippocampus and the prefrontal cortex — use two different brain-wave frequencies to communicate as the brain learns to associate unrelated objects. Whenever the brain correctly links the objects, the waves oscillate at a higher frequency, called “beta,” and when the guess is incorrect, the waves oscillate at a lower “theta” frequency. Read more

  • How brain waves guide memory formation

    Miller Lab
    , ,

    MIT News Office: Neurons hum at different frequencies to tell the brain which memories it should store.
    New discovery from the Miller Lab

    Anne Trafton | MIT News Office
    February 23, 2015
    Our brains generate a constant hum of activity: As neurons fire, they produce brain waves that oscillate at different frequencies. Long thought to be merely a byproduct of neuron activity, recent studies suggest that these waves may play a critical role in communication between different parts of the brain.

    A new study from MIT neuroscientists adds to that evidence. The researchers found that two brain regions that are key to learning — the hippocampus and the prefrontal cortex — use two different brain-wave frequencies to communicate as the brain learns to associate unrelated objects. Whenever the brain correctly links the objects, the waves oscillate at a higher frequency, called “beta,” and when the guess is incorrect, the waves oscillate at a lower “theta” frequency. Read more

  • New paper – Working Memory Capacity: Limits on the Bandwidth of Cognition

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    Miller, E.K. and Buschman, T.J. (2015)  Working memory capacity: Limits on the bandwidth of cognition. Daedalus, Vol. 144, No. 1, Pages 112-122.  View PDF

    Why can your brain store a lifetime of experiences but process only a few thoughts at once? In this article we discuss “cognitive capacity” (the number of items that can be held “in mind” simultaneously) and suggest that the limit is inherent to processing based on oscillatory brain rhythms, or “brain waves,” which may regulate neural communication. Neurons that “hum” together temporarily “wire” together, allowing the brain to form and re-form networks on the fly, which may explain a hallmark of intelligence and cognition: mental flexibility. But this comes at a cost; only a small number of thoughts can fit into each wave. This explains why you should never talk on a mobile phone when driving.

  • Interareal oscillatory synchronization in top-down neocortical processing

    Miller Lab

    Bressler and Richter review evidence that top-down processing in the cortex depends on synchronization of oscillatory rhythms between brain areas. More specifically, they hypothesize that beta band (13-30 Hz) synchrony conveys information about behavioral context (task information) to neurons in sensory cortex.

  • Communication through coherence with inter-areal delays

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    Andre Bastos and colleagues review an update the communication-through-coherence (CTC) hypothesis.  They propose that bi-directional cortical communication involves separate feedforward and feedback mechanisms that are separate both anatomically and spectrally.

  • Theta Oscillations Modulate Attentional Search Performance Periodically

    Miller Lab

    Several lines of evidence suggests that searching a visual scene depends on an intrinsic periodicity.  We scan the scene by moving the spotlight of attention at regular intervals.  For example, Buschman and Miller (2009) found neurophysiological evidence in the frontal eye fields for regular shifts of attention at 25 Hz (i.e., every 40 ms).  Dugue et al (2014) have now found evidence in humans using EEG recording and TMS stimulation in humans.   They found successful search was associated with oscillations and phase resetting at 6 Hz.  TMS applied at different intervals found disruption of search at a periodicity corresponding to 6 Hz.  This was slower than reported by Buschman and Miller (2009), but that could be because Dugue et al used a more difficult search task.

    This paper:
    Theta Oscillations Modulate Attentional Search Performance Periodically
    Laura Dugué, Philippe Marque, and Rufin VanRullen  Journal of Cognitive Neuroscience, 2014

    For further reading:
    Buschman, T.J. and Miller, E.K. (2009) Serial, covert, shifts of attention during visual search are reflected by the frontal eye fields and correlated with population oscillations. Neuron, 63: 386-396. View PDF »

  • Frontoparietal Correlation Dynamics Reveal Interplay between Integration and Segregation during Visual Working Memory

    Miller Lab

    Dotson et al recorded neural activity in the prefrontal and parietal cortex during a working memory task.  As previous studies have reported (e.g., Buschman and Miller, 2007) they found long range synchronization of 8-25 Hz oscillations between the areas.  Interestingly, there found both phase synchronization at 0 and 180 degrees suggesting that the 0 deg phase synchrony helped form networks between the areas whereas the 180 deg (anti-phase) synchrony helped segregate different networks.

    For further reading:
    Buschman, T.J. and Miller, E.K. (2007) Top-down versus bottom-up control of attention in the prefrontal and posterior parietal cortices. Science. 315: 1860-1862  View PDF »

  • Burst Firing Synchronizes Prefrontal and Anterior Cingulate Cortex during Attentional Control

    Miller Lab

    Womelsdorf et al found that bursts of neural activity in the prefrontal cortex and anterior cingulate synchronize at gamma and beta frequencies during focused attention.  Non-burst activity did not show long-range synchronization.  Burst synchronization may underlie the formation of long-range networks.

  • Gamma Oscillations Underlie the Maintenance of Feature-Specific Information and the Contents of Visual Working Memory

    Miller Lab

    Gamma-band oscillations have been associated with holding information in working memory.  Is it just a general increase in gamma or do gamma oscillations actually maintain and convey specific information?  A new study by Honkanen et al suggests that it does contain information.  The strength and topography of gamma oscillations reflected memorized visual features as well as the amount of information in working memory.

    We’ve also shown that information about  two different objects can be carried in different phases of gamma band oscillations:
    Siegel, M., Warden, M.R., and Miller, E.K. (2009) Phase-dependent neuronal coding of objects in short-term memory. Proceedings of the National Academy of Sciences, 106: 21341-21346. View PDF »
    Read commentary by Vogel and Fukuda

  • Frontoparietal Correlation Dynamics Reveal Interplay between Integration and Segregation during Visual Working Memory

    Miller Lab

    Dotson et al report both 0 and 180 deg phase synchrony between the prefrontal and parietal cortices during a working memory task, suggestion both formation and segregation of different functional networks by neural synchrony.