The Miller Lab

  • Synchronized brain waves enable rapid learning

    Miller Lab
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    Antzoulatos EG and Miller EK  (in press) Increases in Functional Connectivity between Prefrontal Cortex and Striatum during Category Learning. Neuron, in press.
    DOI: http://dx.doi.org/10.1016/j.neuron.2014.05.005

    Animals were trained to learn new category groupings by trial and error.  Once they started to “get” the categories, there was an increase in beta-band synchrony between the prefrontal cortex and striatum, two brain areas critical for learning.  By the time the categories were well-learned, the beta synchrony between the areas became category-specific, that is, unique sets of sites in the prefrontal cortex and striatum showed increased beta synchrony for the two different categories.  This suggests that synchronization of brain rhythms can quickly establish new functional brain circuits and thus support cognitive flexibility, a hallmark of intelligence.

    MIT Press release:
    Synchronized brain waves enable rapid learning
    MIT study finds neurons that hum together encode new information.

  • Functions of gamma-band synchronization in cognition

    Miller Lab

    Gamma band oscillations are seen throughout the cortex and subcortex.  Do they have a single or different functions?  Bosman et al review the literature and conclude the latter but nonetheless point out that gamma likely rises from a cortical motif involving interactions between excitatory and inhibitory neurons. So, just as activity of individual neurons means different things in different brain areas so does gamma rhythms.

  • Videos: Rhythmic Dynamics and Cognition 6-4-13

    Miller Lab
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    See lectures from the Cognitive Rhythms Collaborative conference on Rhythmic Dynamics and Cognition, which took place on June 4, 2013 at MIT.

    Talks:
    Elizabeth Buffalo: Neural Signals for Memory and Space in the Primate Medial Temporal Lobe
    Earl K. Miller: Cognition is Rhythmic
    Robert Knight: Oscillations and Human PFC
    Peter Ulhaas: Neural Oscillations in Schizophrenia: Perspectives from MEG
    Charles Schroeder: Neural Substrates of Temporal Prediction in Active Sensing
    Peter Brown: Beta Oscillations in the Human Basal Ganglia
    Christa van Dort: Optogenetic Activation of Cholinergic Neurons in the PPT Induces REM Sleep
    Rosalyn Doran: Dynamic Causal Modeling and Neurophysiology
    Liam Paninski: Statistical Neuroscience
    Astrid Prinz: How do rhythmically active circuits “analyze” their own activity?

  • Mini-Symposium: Frontiers in Non-Invasive Brain Stimulation – 4/16/14 in Boston

    Miller Lab

    Cognitive Rhythms Collaborative and Center for
    Computational Neuroscience and Neural Technology

    Spring 2014 Mini-Symposium
    Frontiers in Non-Invasive Brain Stimulation

    Wednesday, April 16, 2014 at 1 pm

    Boston University Photonics Center 206
    8 Saint Mary Street
    Boston, MA 02215

    1:00 – 1:15  Registration

    1:15 – 2:00  Dr. Lucas Parra, City College of New York
    “Transcranial electrical stimulation: mechanisms and targeting”

    2:00 – 2:45 Dr. Tommi Raij, Massachusetts General Hospital
    “Transcranial magnetic stimulation: mechanisms and navigation”

    2:45 – 3:00  Break

    3:00 – 3:45  Dr. Noah Philip, Alpert Medical School of Brown University
    “Clinical implications of frequency dependent neuromodulation”

    3:45 – 4:30  Dr. Alvaro Pascual-Leone, Harvard Medical School
    “Characterizing and guiding brain networks with noninvasive brain stimulation”

    4:30    Discussion / Reception

    Registration free, but required. Email xiaoshi@bu.edu.

  • Behavioral Oscillations in Attention

    Miller Lab

    Song et al examined oscillatory activity in humans performing an attention task.  They found that phase-locking between theta and alpha bands.  An uninformative cue initiated alpha pulse at a theta rhythm that seemed to reflect alternating sampling of the uninformative and informative cues.

  • Entrainment of Prefrontal Beta Oscillations Induces an Endogenous Echo and Impairs Memory Formation

    Miller Lab

    Recent studies have suggested that beta-band oscillatory synchrony plays a role in cognition.  For example, different networks of neurons in the prefrontal cortex dynamically synchronize at beta as animals switch between two different task rules (Buschman et al., 2012) suggesting that beta synchrony is forming the neural ensembles for the rules.  Different items simultaneously held in working memory line-up on different phases of beta/low-gamma oscillations, as if the brain is juggling the two items 30 times a second (Siegel et al., 2009). Hanslmayr et al disrupted these fine temporal relations by stimulating the human with beta-band TMS pulses.   Beta stimulation of the left inferior frontal gyrus impaired memory formation while stimulation at other frequencies did not.  There was a beta “echo” that outlasted the stimulation.  Subjects with better beta entrainment showed more memory impairment.  This lends support for the role of beta rhythms in cognition by showing a causal relationship between beta desynchrony and memory.

    This paper:
    Simon Hanslmayr, Jonas Matuschek, Marie-Christin Fellner, Entrainment of Prefrontal Beta Oscillations Induces an Endogenous Echo and Impairs Memory Formation, Current Biology, Available online 27 March 2014, ISSN 0960-9822

    References
    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

    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

  • Stimulus repetition modulates gamma-band synchronization in primate visual cortex

    Miller Lab

    It has long been known (since my dissertation – ahem) that repetitions of a visual stimulus result in reduced spiking activity of individual neurons.  This is curious because repetition does not weaken the perception of the stimulus.   If spiking of individual neurons alone is responsible for perception, why doesn’t the perception weaken? Brunet et al showed that stimulus repetition produces increases in gamma band synchrony (40-90 Hz) within and between higher and lower order visual cortical areas.  The increased synchrony can maintain efficacy of signalling of the stimulus despite the decrease of neuron spiking.  Gamma-band synchrony of the spikes increases in general but decreases for weakly driven neurons.  Thus, stimulus repetition may prune the neural representation of a stimulus while increased gamma synchronization increases neuron signalling, resulting in a leaner and meaner stimulus representation.   This lends further support for the role in gamma-band synchrony in bottom-up sensory processing (e.g., Buschman and Miller, 2007).

    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 »

    Incidentally, the effect of stimulus repetition on spiking activity was my first first-author publication:
    Miller, E.K., Gochin, P.M., and Gross, C.G. (1991) A habituation-like decrease in the responses of neurons in inferior temporal cortex of the macaque. Visual Neuroscience 7:357-362.

  • Fronto-Parietal Anatomical Connections Influence the Modulation of Conscious Visual Perception

    Miller Lab

    Quentin et al examined the relationship between white matter connectivity between the frontal and parietal cortices and the improvement of visual perception by beta oscillatory synchrony between them.  They used diffusion imaging to examine the white matter connectivity and used transcranial magnetic stimulation (TMS) over the right frontal eye fields (FEF) to induce beta oscillations.  Individuals that showed greater perceptual improvement with the beta TMS also had stronger white matter connectivity.

  • Neural circuits as computational dynamical systems

    Miller Lab

    Sussillo reviews the use of recurrent neural networks (RNNs) to study cortical neurons.  RNNs can explain the high-dimensional, mixed-selectivity properties and oscillatory temporal dynamics of cortical neurons.  They share many features of cortical networks including feedback, nonlinearity, and parallel and distributed computing

  • Timing of Single-Neuron and Local Field Potential Responses in the Human Medial Temporal Lobe

    Miller Lab

    Rey et al recorded local field potentials and neuron spikes from the human medial temporal lobe during a recognition task.  Single-neuron responses were preceded by a global increase in theta oscillations and a local and stimulus-specific increase in gamma oscillations.  The LFPs responses were correlated with conscious recognition and neuron spiking was time-locked to the LFPs.  They suggest that theta reflects a global recognition signal whereas phase-locked of neurons to gamma reflects activation of local circuits that represent the recognized stimulus.