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[0] Karni A, Meyer G, Rey-Hipolito C, Jezzard P, Adams MM, Turner R, Ungerleider LG, The acquisition of skilled motor performance: fast and slow experience-driven changes in primary motor cortex.Proc Natl Acad Sci U S A 95:3, 861-8 (1998 Feb 3)

[0] Pleger B, Blankenburg F, Ruff CC, Driver J, Dolan RJ, Reward facilitates tactile judgments and modulates hemodynamic responses in human primary somatosensory cortex.J Neurosci 28:33, 8161-8 (2008 Aug 13)

[0] Kamitani Y, Tong F, Decoding the visual and subjective contents of the human brain.Nat Neurosci 8:5, 679-85 (2005 May)

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ref: -0 tags: neuronal assemblies maass hebbian plasticity simulation austria fMRI date: 10-27-2020 21:39 gmt revision:0 [head]

PMID-32381648 A model for structured information representation in neural networks in the brain

  • Using randomly connected E/I networks, suggests that information can be "bound" together using fast Hebbian STDP.
  • That iss 'assemblies' in higher-level areas reference sensory information through patterns of bidirectional connectivity.
  • These patterns emerge spontaneously following disinihbition of the higher-level areas.
  • Find the results underwhelming, but the discussion is more interesting.
    • E.g. there have been a lot of theoretical and computational-experimental work for how concepts are bound together into symbols or grammars
    • Actually find the referenced fMRI studies interesting, too: they imply that you can observe the results of structural binding in activity of the superior tempporal gyrus.
  • I'm more in favor of dendritic potentials or neuronal up/down states to be a fast and flexible way of maintaining 'sumbol membership' --
    • But it's not as flexible as synaptic plasticity, which, obviously, populates the outer product between 'region a' and 'region b' with a memory substrate, thereby spanning the range of plausible symbol-bindings.
    • Inhibitory interneurons can then gate the bindings, per morphological evidence
    • But but, I don't think anyone has shown that you need protein synthesis for perception, as you do for LTP (modulo AMPAR cycling).
      • Hence I'd argue that localized dendritic potentials can serve as the flexible outer-product 'memory tag' for presence in an assembly.
        • Or maybe they are used primarily for learning, who knows!

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ref: -2008 tags: representational similarity analysis fMRI date: 02-15-2019 02:27 gmt revision:1 [0] [head]

PMID-19104670 Representational Similarity Analysis – Connecting the Branches of Systems Neuroscience

  • Nikolaus Kriegeskorte, Marieke Mur, and Peter Bandettini
  • Alright, there seems to be no math in the article (?), but it seems well cited so best be on the radar.
  • RDM = representational dissimilarity matrices
    • Just a symmetric matrix of dissimilarity, e.g. correlation, euclidean distance, absolute activation distance ( L 1L_1 ?)
  • RSA = representational similarity analysis
    • Comparison of the upper triangle of two RDMs, using the same metrics.
    • Or, alternately, second-order isomorphism.
  • So.. high level:

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ref: Lehericy-2005.08 tags: fMRI motor_learning basal_ganglia STN subthalamic date: 01-25-2012 00:20 gmt revision:2 [1] [0] [head]

PMID-16107540[0] Distinct basal ganglia territories are engaged in early and advanced motor sequence learning

  • generally a broad, well-referenced study.
  • they used a really high-field magnet (3T) during tapping-learning task over the course of a month.
  • STN was activated early in motor learning, but not afterward, specifically the sequence learning
  • during the course of learning (an as the task became progressively more automatic) associative striatal activation shifted to motor activity.
    • STN could act by inhibiting competing motor outputs, thus building a temporally ordered sequence of movements.
  • SN was active throughout the course of the experiment.
  • during the 'fast learning' stage, there was transient activation of the ACC
  • also during the beginning portion of motor learning lobules V and VI of the cerebellum were activated.
  • rostral premotor and prefrontal cortical areas are connected to the associative territory of the striatum, which projects back to the frontal cortex the VA/VL nuclei of the thalamus.

____References____

[0] Lehéricy S, Benali H, Van de Moortele PF, Pélégrini-Issac M, Waechter T, Ugurbil K, Doyon J, Distinct basal ganglia territories are engaged in early and advanced motor sequence learning.Proc Natl Acad Sci U S A 102:35, 12566-71 (2005 Aug 30)

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ref: Fletcher-2005.07 tags: explicit implicit learning fMRI frontal_cortex MT date: 12-07-2011 03:58 gmt revision:1 [0] [head]

PMID-15537672[0] On the Benefits of not Trying: Brain Activity and Connectivity Reflecting the Interactions of Explicit and Implicit Sequence Learning

quote: ünder certain curcumstances, automatic learning may be attenuated by explicit memory processes" : expicit attemps to learn a difficult sequence (compared to a control) produces a failure in implicit learning, and this failure is caused by the supression of learning rather than the expression. There is a deleterious effect of explicit search on implicit learning.

  • implicit learning is hampered by explicit search.
  • Compare this to the known benefits of coginive effort on motor learning ... (?)

____References____

[0] Fletcher PC, Zafiris O, Frith CD, Honey RA, Corlett PR, Zilles K, Fink GR, On the benefits of not trying: brain activity and connectivity reflecting the interactions of explicit and implicit sequence learning.Cereb Cortex 15:7, 1002-15 (2005 Jul)

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ref: Seidler-2006.11 tags: basal ganglia learning fMRI adaptation date: 03-11-2009 21:34 gmt revision:4 [3] [2] [1] [0] [head]

PMID-16794848[9] Bilateral basal ganglia activation associated with sensorimotor adaptation.

  • shows that the basal ganglia is highly active durnig the initial stages of sensory motor adaptation (cursor rotation).
    • specifically: "We observed activation in the right globus pallidus and putamen, along with the right prefrontal, premotor and parietal cortex," to support spatial cognitive processes of adaptation.. and .. "activation in the left globus pallidus and caudate nucleus, along with the left premotor and supplementary motor cortex, which may support the sensorimotor processes of adaptation"
  • human subjects in a 3T MRI scanner; BOLD signal.

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ref: Porro-1996.12 tags: motor imagery fMRI practice date: 02-19-2009 22:50 gmt revision:0 [head]

PMID-8922425 Primary Motor and Sensory Cortex Activation during Motor Performance and Motor Imagery: A Functional Magnetic Resonance Imaging Study.

  • says exactly what you might expect: that the motor cortex is active during motor imagery, and the regions active during motor performance and motor imagery are overlapping.

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ref: Karni-1998.02 tags: motor learning skill acquisition fMRI date: 10-08-2008 21:05 gmt revision:1 [0] [head]

PMID-9448252[0] The acquisition of skilled motor performance: Fast and slow experience-driven changes in primary motor cortex

  • a few minutes of daily practice on a sequential finger opposition task induced large, incremental performance gains over a few weeks of training
  • performance was lateralized
  • limited training experience can be sufficient to trigger performance gains that require time to become evident.
  • learning is characterized by two stages:
    • "fast” learning, an initial, within-session improvement phase, followed by a period of consolidation of several hours duration
      • possibly this is due to synaptic plasticity.
    • and then “slow” learning, consisting of delayed, incremental gains in performance emerging after continued practice
      • In many instances, most gains in performance evolved in a latent manner not during, but rather a minimum of 6–8 hr after training, that is, between sessions
      • this is thought to correspond to the reorganization of M1 & other cortical structures.
  • long-term training results in highly specific skilled motor performance, paralleled by the emergence of a specific, more extensive representation of a trained sequence of movements in the contralateral primary motor cortex. this is seen when imaging for activation using fMRI.
  • why is there the marked difference between declarative learning, which often only takes one presentation to learn, and procedural memory, which takes several sessions to learn? Hypothetically, they require different neural substrates.
  • pretty good series of references...

____References____

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ref: Pleger-2008.08 tags: S1 reward fMRI human date: 10-07-2008 23:06 gmt revision:1 [0] [head]

PMID-18701678[0] Reward facilitates tactile judgments and modulates hemodynamic responses in human primary somatosensory cortex.

  • "Remarkably, primary somatosensory cortex contralateral to the judged hand was reactivated at the point of reward delivery, despite the absence of concurrent somatosensory input at that time point."
    • hence, it is probably rostral to the central sulcus too.
  • the same as http://m8ta.com/index.pl?pid=630
  • rewarded humans with $
  • people had to discriminate the frequency of electrical stimulation to their left/right index fingers. i guess a vibrator would have been hard in the magnet of an MRI machine.
  • reward cue was visually instructed.
  • reference Janaina's paper. http://www.jneurosci.org/cgi/content/full/27/39/10608

____References____

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ref: Kamitani-2005.05 tags: BMI ATR fMRI date: 04-04-2007 15:20 gmt revision:0 [head]

PMID-15852014[] Decoding the visual and subjective contents of the human brain

  • used a linear SVM to decode visual orientation from voxel responses.
  • also were able to decode which direction of grating the subjects were paying attention to.

____References____