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[0] Atallah HE, Lopez-Paniagua D, Rudy JW, O'Reilly RC, Separate neural substrates for skill learning and performance in the ventral and dorsal striatum.Nat Neurosci 10:1, 126-31 (2007 Jan)

[0] Matsuzaka Y, Picard N, Strick PL, Skill representation in the primary motor cortex after long-term practice.J Neurophysiol 97:2, 1819-32 (2007 Feb)

[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)

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ref: -2015 tags: PaRAC1 photoactivatable Rac1 synapse memory optogenetics 2p imaging mouse motor skill learning date: 10-30-2019 20:35 gmt revision:1 [0] [head]

PMID-26352471 Labelling and optical erasure of synaptic memory traces in the motor cortex

  • Idea: use Rac1, which has been shown to induce spine shrinkage, coupled to a light-activated domain to allow for optogenetic manipulation of active synapses.
  • PaRac1 was coupled to a deletion mutant of PSD95, PSD delta 1.2, which concentrates at the postsynaptic site, but cannot bind to postsynaptic proteins, thus minimizing the undesirable effects of PSD-95 overexpression.
    • PSD-95 is rapidly degraded by proteosomes
    • This gives spatial selectivity.
  • They then exploited the dendritic targeting element (DTE) of Arc mRNA which is selectively targeted and translated in activiated dendritic segments in response to synaptic activation in an an NMDA receptor dependent manner.
    • Thereby giving temporal selectivity.
  • Construct is then PSD-PaRac1-DTE; this was tested on hippocampal slice cultures.
  • Improved sparsity and labelling further by driving it with the Arc promoter.
  • Motor learning is impaired in Arc KO mice; hence inferred that the induction of AS-PaRac1 by the Arc promoter would enhance labeling during learning-induced potentiation.
  • Delivered construct via in-utero electroporation.
  • Observed rotarod-induced learning; the PaRac signal decayed after two days, but the spine volume persisted in spines that showed Arc / DTE hence PA labeled activity.
  • Now, since they had a good label, performed rotarod training followed by (at variable delay) light pulses to activate Rac, thereby suppressing recently-active synapses.
    • Observed both a depression of behavioral performance.
    • Controlled with a second task; could selectively impair performance on one of the tasks based on ordering/timing of light activation.
  • The localized probe also allowed them to image the synapse populations active for each task, which were largely non-overlapping.

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ref: Fontani-2007.12 tags: mental training skilled motor control date: 01-03-2012 02:33 gmt revision:2 [1] [0] [head]

PMID-18229536[0] Effect of mental imagery on the development of skilled motor actions.

  • with trained subjects (performing something called Ura-Shuto-Uchi (Japanese? but the researchers are Italian)) showed a decrease in reaction time and EMG activity, as well as a increase in movement speed, muscle strength, power, and work. These results did not apply to untrained individuals. EEG also apparently changed vs. the untrained condition.

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[0] Fontani G, Migliorini S, Benocci R, Facchini A, Casini M, Corradeschi F, Effect of mental imagery on the development of skilled motor actions.Percept Mot Skills 105:3 Pt 1, 803-26 (2007 Dec)

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ref: Atallah-2007.01 tags: striatum skill motor learning VTA substantia nigra basal ganglia reinforcement learning date: 12-31-2011 18:59 gmt revision:3 [2] [1] [0] [head]

PMID-17187065[0] Separate neural substrates for skill learning and performance in the ventral and dorsal striatum.

  • good paper. via SCLin's blog. slightly confusing anatomical terminology.
  • tested in rats, which has a anatomically different basal ganglia system than primates.
  • Rats had to choose which driection in a Y maze based on olfactory cues. Normal rats figure it out in 60 trials.
  • ventral striatum (nucleus accumbens here in rats) connects to the ventral prefrontal cortices (for example, the orbitofrontal cortex)
    • in primates, includes the medial caudate, which has been shown in fMRI to respond to reward prediction error. Neural activity in the caudate is attenuated when a monkey reaches optimal performance.
  • dorsal parts of the striatum (according to web: caudate, putamen, globus pallidus in primates) connect to the dorsal prefrontal and motor cortices
    • (according to them:) this corresponds to the putamen in primates. Activity in the putamen reflects performance but not learning.
    • activity in the putamen is highest after successful learning & accurate performance.
  • used muscimol (GABAa agonist, silences neural activity) and AP-5 (blocks NMDA based plasticity), in each of the target areas.
  • dorsal striatum is involved in performance but not learning
    • Injection of muscimol during acquisition did not impair test performance
    • Injection of muscimol during test phase did impair performance
    • Injection of AP-5 during acquisition had no effect.
    • in acquisition sessions, muscimol blocked instrumental response (performance); but muscimol only has a small effect when it was injected after rats perfected the task.
      • Idea: consistent behavior creates a stimulus-response association in extrastriatal brain areas, e.g. cerebral cortex. That is, the basal ganglia is the reinforcement signal, the cortex learns the association due to feedback-driven behavior? Not part of the habit system, but make and important contribution to goal-directed behavior.
      • This is consistent with the observation that behavior is initially goal driven but is later habitual.
    • Actually, other studies show that plasticity in the dorsal striatum may be detrimental to instrumental learning.
    • The number of neurons that fire just before the execution of a response is larger in the putamen than the caudate.
  • ventral striatum is involved in learning and performance.
    • Injection of AP-5 or muscimol during acquisition (learning behavior) impairs test performance.
    • Injection of AP-5 during test performance has no effect , but muscimol impairs performance.
  • Their data support an actor-director-critic architecture of the striatum:
    • Actor = dorsal striatum; involved in performance, but not in learning them.
    • Director = ventral striatum; quote "it somehow learns the relevant task demands and directs the dorsal striatum to perform the appropriate action plans, but, crucially, it does not train the dorsal striatum"
      • ventrai striatum acts through the orbitofrontal cortex that mantains representations of task-reward contingencies.
      • ventral striatum might also select action selection through it's projections to the substantia nigra.
    • Critic = dopaminergic inputs from the ventral tegmental area and substantia nigra.

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ref: life-0 tags: NYTimes genius talent skill learning date: 06-27-2009 18:36 gmt revision:1 [0] [head]

http://www.nytimes.com/2009/05/01/opinion/01brooks.html?_r=1 -- the 'modern view' of genius. Makes sense to me.

  • quote: "By practicing in this way, performers delay the automatizing process. The mind wants to turn deliberate, newly learned skills into unconscious, automatically performed skills. But the mind is sloppy and will settle for good enough. By practicing slowly, by breaking skills down into tiny parts and repeating, the strenuous student forces the brain to internalize a better pattern of performance." -- exactly!!
  • quote: The primary trait she possesses is not some mysterious genius. It’s the ability to develop a deliberate, strenuous and boring practice routine.
  • It's not who you are, it's what you do. (law of the cortex: you get good at what you do).
  • The subconcious / ability to push skills to the subconcious should not be neglected. Insight apparently is mostly subconcious, and rapid decisions are too - the rational/concious brain is simply too slow and deliberate to form realtime behavior & reactions, but as the above quote highlights, it is also too 'lazy' and accepting to carefully hone a true skill. This requires attention.
  • From the guardian -- "Sometimes an overload of facts is the mark of a dull and pedestrian mind, the antithesis of intelligence."
    • also: "Intelligence is a matter of output, not scores on a test." We know genius & talent by it's output.

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ref: Matsuzaka-2007.02 tags: skill learning M1 motor control practice cortex date: 03-20-2009 18:31 gmt revision:1 [0] [head]

PMID-17182912[0] Skill Representation in the Primary Motor Cortex After Long-Term Practice

  • The acquisition of motor skills can lead to profound changes in the functional organization of the primary motor cortex (M1) yes
  • 2 task modes: random target acquisition, and one of 2 repeating sequences (predictable, repeating mode)
  • 2 years of training -> 40% of units were differentially active during the two task modes
  • variations in movement types in the two classes did not fully explain the difference in activity between the 2 tasks
    • M1 neurons are more influence by the task than the actual kinematics.

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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...

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