• Peter Lakatos and Charlie Schroeder have conducted elegant work showing that the brain entrains its rhythms to attended sensory inputs.  Here, Lakatos et al show that normal human subjects show increased rhythmic entrainment with increasing task demands,  By contrast, schizophrenic patients are less able to match their brain rhythms to attended stimuli, even when the task is highly demanding.

    Miller Lab work cited:
    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  The Scientist’s “Hot Paper” for October 2009. View PDF »

    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 »

  • Propofol-induced unconsciousness decreases posterior alpha rhythms and increases frontal alpha rhythms.  Vijayan et al show that this may be due to different actions on posterior vs anterior projecting thalamic nuclei.

  • Totah et al find that increased synchrony between the prelimbic cortex and anterior cingulate cortex before stimulus onset predicted behavioral choices.  Further, there was a switch from beta synchrony during attention to delta synchrony before the behavioral response.  This shows, among other things, that the same neurons can participate in different functional networks by virtue of how that synchronize with other neurons.

    This paper is one of several recent studies providing evidence that oscillatory synchrony allows multiplexing of neural function.  Here’s an excerpt from Miller and Fusi (2013) that summarizes this point:

    “It (oscillatory synchrony) could allow neurons to communicate different messages to different targets depending on whom they are synchronized with (and how, e.g., phase, frequency).    For example, rat hippocampal CA1 neurons preferentially synchronize to the entorhinal or CA3 neurons at different gamma frequencies and theta phases (Colgin et al, 2009).  Different frequency synchronization between human cortical areas supports recollection of spatial vs temporal information (Watrous et al., 2013).  Different phases of cortical oscillations preferentially signal different pictures simultaneously held in short-term memory (Siegel et al., 2009).  Monkey frontal and parietal cortices synchronize more strongly at lower vs higher frequency for top-down vs bottom-up attention, respectively (Buschman and Miller, 2007).  Entraining the human frontal cortex at those frequencies produces the predicted top-down vs bottom-up effects on behavior (Chanes et al., 2013).  Thus, activity from the same neurons has different functional outcomes depending on their rhythmic dynamics.”

    Miller, E.K. and Fusi, S. (2013) Limber neurons for a nimble mind. Neuron. 78:211-213. View PDF

  • Ekstrom and Watrous review the role of low frequency oscillatory coupling in cognition.  The propose that different  resonant frequencies within the same networks support movement vs memory related functions.  They provide further evidence and argument for a role for oscillatory coupling in multiplexing of function.  In other words, different frequency coupling can allow the same networks to have different roles by allowing them to communicate different messages to different targets.

    Miller Lab work on oscillatory coupling and multiplexing:
    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 »

    Miller, E.K. and Buschman, T.J. (2013) Cortical circuits for the control of attention.  Current Opinion in Neurobiology.  23:216–222  View PDF »

  • Kometer et al show that psilocybin decreased spontaneous alpha oscillations which precluded the usual decrease in alpha when a visual stimulus is presented.  Psilocybin may result in a brain state in which normal stimulus-driven cortical excitation is overwhelmed by spontaneous neuronal excitation resulting in altered perception and hallucinations.

    We recently found evidence that alpha oscillations are useful for clearing out unwanted thoughts (neural ensembles) that could interfere with the current cognitive demands:

    • 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
  • More evidence for a role for beta coherence in cognition.
    Lipsman et al
     find that an increase in beta coherence in human VM prefrontal cortex just before humans subjectively evaluated faces as “sad” but not before “happy” judgments, especially true when the faces were more ambiguous and thus more difficult to judge.

    Miller Lab work on beta coherence and cognition:

    • Miller, E.K. and Buschman, T.J. (2013) Cortical circuits for the control of attention.  Current Opinion in Neurobiology.  23:216–222  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
    • 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 »
    • 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 »
  • He uses non-invasive stimulation to phase cancel the tremor.   The stimulation mirrors but is opposite phase of the motor cortex oscillation.  Reduces tremor by ~40%  Brittain et al 2013

  • Charlie Schroeder shows us the laminar profile of oscillations in cortex.  Different strengths for different frequency bands in different cortical layers.  Attention phase-synchronizes oscillations across layers facilitating communication between them. See Lakatos et al (2005) J. Neurophys.

    Circuits from different thalamic nuclei  to cortex, one broad and modulatory, the other narrow and specific, may regulate oscillatory entrainment.

    New Neuron paper shows cortical entrainment that matches periodic sensory inputs; phase depended on the attended frequency content., enhancing attended representations.  Lakatos et al 2013

    Entrainment may explain cocktail party effect. Low frequency phase and high gamma power track attended speech.  Zion Golumbic et al

  • If you are interested in cognition, brain rhythms, and, especially, brain rhythms and cognition, this is the place to be.
    http://cogrhythms.bu.edu/conference.htm

    The Rhythmic Dynamics and Cognition Conference is a two-day event sponsored by the Cognitive Rhythms Collaborative (CRC). The program will be held at the Brain Building (Building 46) on the MIT campus (Room 3002) and will include lectures, a reception, and a poster session.

    Speakers include:

    • Pascal Fries, (Ernst Strungmann Institute (ESI), Frankfurt)
    • Elizabeth Buffalo (Emery University)
    • Charlie Schroeder (Nathan Kline Institute)
    • Peter Brown (University College London)
    • Fiona Le Beau (Newcastle University)
    • Earl Miller (MIT)
    • Charlie Wilson (University of Texas, San Antonio)
    • Peter Uhlhaas (University of Glasgow)
    • Christa van Dort (Mass. General Hospital)
    • Markus Siegal (University of Tubingen)
    • Robert Knight (UC Berkely)
  • Visual attention modulates several aspects of neural coding.  There is an increase in firing rate and changes in temporal dynamics: a reduction of neural variance and noise correlation as well as changes in oscillatory synchronization.   The authors used glutamatergic receptor activation, combined with neurophysiological recording to show that the NMDA receptor is responsible for attention -related changes in neural temporal dynamics but not for  increases in firing rate.  Thus,  different  neurophysiological mechanisms that underlie attention can be dissociated at the receptor level. This supports the hypothesis that attention is mediated in part by the temporal dynamics of neural activity, not merely changes in the firing rate of neurons, and that the changes temporal dynamics are not simply a byproduct of changes in firing rate.
    Herrero et al (2013) Neuron

    For a further discussion of the role of temporal dynamics in attention see:
    Miller, E.K. and Buschman, T.J. (2013) Cortical circuits for the control of attention.  Current Opinion in Neurobiology.  23:216–222  View PDF »

    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 »

    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 »