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Study: Gamma and beta bursts during working memory readout suggest roles in its volitional control Citation: Mikael Lundqvist, Pawel Herman, Melissa R. Warden,

Study: Gamma and beta bursts during working memory readout suggest roles in its volitional control Citation: Mikael Lundqvist, Pawel Herman, Melissa R. Warden, Scott L. Brincat & Earl K. Miller. Nature Communications 9, Article number: 394 (2018). Link: https://dx.doi.org/10.1038/s41467-017-02791-8 https://dx.doi.org/10.1038/s41467-017-02791-8 DOI: 10.1038/s41467-017-02791-8 Abstract: Working memory (WM) activity is not as stationary or sustained as previously thought. There are brief bursts of gamma (~50–120 Hz) and beta (~20–35 Hz) oscillations, the former linked to stimulus information in spiking. We examined these dynamics in relation to readout and control mechanisms of WM. Monkeys held sequences of two objects in WM to match to subsequent sequences. Changes in beta and gamma bursting suggested their distinct roles. In anticipation of having to use an object for the match decision, there was an increase in gamma and spiking information about that object and reduced beta bursting. This readout signal was only seen before relevant test objects, and was related to premotor activity. When the objects were no longer needed, beta increased and gamma decreased together with object spiking information. Deviations from these dynamics predicted behavioral errors. Thus, beta could regulate gamma and the information in WM.

tomalpha 9y ago
I can’t tell from this, but does this demonstrate a causal link or is the headline somewhat disconnected from the paper? That is to say, does the brain truly rely on beta rhythms, or are they just a symptom of something else?
- maxander 9y ago
  I think the answer is necessarily "no," because the rhythm is a sign we observe of some functional system in the brain, not the functional system itself. Similar to how your heart rate is just a sign of the beating of your heart, only the latter of which is a real functional mechanism. Something is happening in the brain that generates these patterns and which also has to do with the cognitive faculties described in the paper; I don't think anyone has a very clear idea what that mechanism is, though. I'm not sure if this answers your question, or is just pedantry. :)
  - tomalpha 9y ago
    Thanks. That sort of answers my question. I think that means that I disagree with the headline because this research doesn’t demonstrate evidence of the brain relying on beta rhythms to control thinking. (From my strictly lay reading).
  - anon1253 9y ago
    The waves come from synchronicity of neurons "firing". When neurons fire there is a flow of ions that causes a potential difference. If a lot of this happens at the same time with some periodicity you can measure this. But it would be like looking at a CPU running some math operations and determining "there is periodic activity in the ALU" (which could be due to memory reads). Now this is a poor analogy because a single neuron doesn't do "one thing" it's massively distributed. My go to argumentation for "how the brain works" (and thus consciousness) has been that it's a massive coincidence detector that tries to encode these coincidences in spike train activity using spike train dependent plasticity. In doing so the brain echoes the coincidences of the neural (sensory) input, and since these encode for some "real" cause-effect you can predict the future: memory is "echoing" in a neural substrate, consciousness is exploiting those "echos" to try to predict the future. I wrote it up in 2011 https://www.dropbox.com/s/huol1vf4j1fs1ll/mind_matters.pdf?dl=0 https://www.dropbox.com/s/huol1vf4j1fs1ll/mind_matters.pdf?d... I've never seen anyone poke holes in this, and even hints at the details of this paper. Guess I chose the wrong career somewhere.
- growlix 9y ago
  The study's design cannot address causality. They report a correlation between beta rhythms and the subjects' behavior. It's unclear whether local field potentials (LFPs), of which "beta rhythms" are one specific frequency band (approximately 12-30hz), are actually a mechanism that the brain uses to transmit information. Information is known to be transmitted via the discharges of single neurons; LFPs represent the aggregate activity of tens of thousands of neurons within ~3mm of a recording electrode. It's possible that these aggregate voltage fluctuations feed back onto the activity of single neurons [0], but LFPs are generally considered an emergent property of populations of neurons as opposed to an information transmission mechanism in their own right. [0] https://www.nature.com/articles/nn.2727 https://www.nature.com/articles/nn.2727
uhhyeahdude 9y ago
Thank you for providing useful, concise, and well-formatted study citations. I'm not in academia as of this year, and it pains me to see this information omitted from posts that would greatly benifit from this. I'll do a better job at including relevant cites in my own submissions.

tomalpha 9y ago

I can’t tell from this, but does this demonstrate a causal link or is the headline somewhat disconnected from the paper? That is to say, does the brain truly rely on beta rhythms, or are they just a symptom of something else?

maxander 9y ago
I think the answer is necessarily "no," because the rhythm is a sign we observe of some functional system in the brain, not the functional system itself. Similar to how your heart rate is just a sign of the beating of your heart, only the latter of which is a real functional mechanism. Something is happening in the brain that generates these patterns and which also has to do with the cognitive faculties described in the paper; I don't think anyone has a very clear idea what that mechanism is, though. I'm not sure if this answers your question, or is just pedantry. :)
- tomalpha 9y ago
  Thanks. That sort of answers my question. I think that means that I disagree with the headline because this research doesn’t demonstrate evidence of the brain relying on beta rhythms to control thinking. (From my strictly lay reading).
- anon1253 9y ago
  The waves come from synchronicity of neurons "firing". When neurons fire there is a flow of ions that causes a potential difference. If a lot of this happens at the same time with some periodicity you can measure this. But it would be like looking at a CPU running some math operations and determining "there is periodic activity in the ALU" (which could be due to memory reads). Now this is a poor analogy because a single neuron doesn't do "one thing" it's massively distributed. My go to argumentation for "how the brain works" (and thus consciousness) has been that it's a massive coincidence detector that tries to encode these coincidences in spike train activity using spike train dependent plasticity. In doing so the brain echoes the coincidences of the neural (sensory) input, and since these encode for some "real" cause-effect you can predict the future: memory is "echoing" in a neural substrate, consciousness is exploiting those "echos" to try to predict the future. I wrote it up in 2011 https://www.dropbox.com/s/huol1vf4j1fs1ll/mind_matters.pdf?dl=0 https://www.dropbox.com/s/huol1vf4j1fs1ll/mind_matters.pdf?d... I've never seen anyone poke holes in this, and even hints at the details of this paper. Guess I chose the wrong career somewhere.
growlix 9y ago
The study's design cannot address causality. They report a correlation between beta rhythms and the subjects' behavior. It's unclear whether local field potentials (LFPs), of which "beta rhythms" are one specific frequency band (approximately 12-30hz), are actually a mechanism that the brain uses to transmit information. Information is known to be transmitted via the discharges of single neurons; LFPs represent the aggregate activity of tens of thousands of neurons within ~3mm of a recording electrode. It's possible that these aggregate voltage fluctuations feed back onto the activity of single neurons [0], but LFPs are generally considered an emergent property of populations of neurons as opposed to an information transmission mechanism in their own right. [0] https://www.nature.com/articles/nn.2727 https://www.nature.com/articles/nn.2727

uhhyeahdude 9y ago

Thank you for providing useful, concise, and well-formatted study citations. I'm not in academia as of this year, and it pains me to see this information omitted from posts that would greatly benifit from this. I'll do a better job at including relevant cites in my own submissions.