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[0] Jackson A, Mavoori J, Fetz EE, Correlations between the same motor cortex cells and arm muscles during a trained task, free behavior, and natural sleep in the macaque monkey.J Neurophysiol 97:1, 360-74 (2007 Jan)

[0] De Cock VC, Vidailhet M, Leu S, Texeira A, Apartis E, Elbaz A, Roze E, Willer JC, Derenne JP, Agid Y, Arnulf I, Restoration of normal motor control in Parkinson's disease during REM sleep.Brain 130:Pt 2, 450-6 (2007 Feb)

[0] Bair W, Koch C, Temporal precision of spike trains in extrastriate cortex of the behaving macaque monkey.Neural Comput 8:6, 1185-202 (1996 Aug 15)[1] Shmiel T, Drori R, Shmiel O, Ben-Shaul Y, Nadasdy Z, Shemesh M, Teicher M, Abeles M, Neurons of the cerebral cortex exhibit precise interspike timing in correspondence to behavior.Proc Natl Acad Sci U S A 102:51, 18655-7 (2005 Dec 20)[2] Mainen ZF, Sejnowski TJ, Reliability of spike timing in neocortical neurons.Science 268:5216, 1503-6 (1995 Jun 9)

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ref: -2021 tags: hippocampal behavior scale plasticity Magee Romani Bittner date: 12-20-2021 22:39 gmt revision:0 [head]

Bidirectional synaptic plasticity rapidly modifies hippocampal representations

  • Normal Hebbian plasticity depends on pre and post synaptic activity & their time course.
  • Three-factor plasticity depends on pre, post, and neuromodulatory activity, typically formalized as an eligibility trace (ET) and instructive signal (IS).
  • Here they show that dendritic-plateau dependent hippocampal place field generation, in particular LTD, is not (quite so) dependent on post synaptic activity.
  • Instead, it appears to be a 'register update' operation, where a new pattern is remembered (through LTP) and an old pattern is forgotten (through LTD).
    • That is, the synapses are updating information, not accumulating information.
  • The eq for a single synapse: ΔW/δt=(W maxW)k +q +(ET*IS)Wk q (ET*IS)\Delta W / \delta t = (W_{max} - W) k^+ q^+(ET * IS) - W k^- q^-(ET * IS)
    • Where k are the learning rates, and q are the nonlinear functions regulating potentiation / depression based on eligibility trace and instructive signal.

I'm still not 100% sure that this excludes any influence on presynaptic activity ... they didn't control for that. But certainly LTD in their model does not require postsynaptic activity; indeed, it may only require net-synaptic homeostasis.

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ref: Jackson-2007.01 tags: Fetz neurochip sleep motor control BMI free behavior EMG date: 09-13-2019 02:21 gmt revision:4 [3] [2] [1] [0] [head]

PMID-17021028[0] Correlations Between the Same Motor Cortex Cells and Arm Muscles During a Trained Task, Free Behavior, and Natural Sleep in the Macaque Monkey

  • used their implanted "neurochip" recorder that recorded both EMG and neural activity. The neurochip buffers data and transmits via IR offline. It doesn't have all that much flash onboard - 16Mb.
    • used teflon-insulated 50um tungsten wires.
  • confirmed that there is a strong causal relationship, constant over the course of weeks, between motor cortex units and EMG activity.
    • some causal relationships between neural firing and EMG varied dependent on the task. Additive / multiplicative encoding?
  • this relationship was different at night, during REM sleep, though (?)
  • point out, as Todorov did, that Stereotyped motion imposes correlation between movement parameters, which could lead to spurrious relationships being mistaken for neural coding.
    • Experiments with naturalistic movement are essential for understanding innate, untrained neural control.
  • references {597} Suner et al 2005 as a previous study of long term cortical recordings. (utah probe)
  • during sleep, M1 cells exhibited a cyclical patter on quiescence followed by periods of elevated activity;
    • the cycle lasted 40-60 minutes;
    • EMG activity was seen at entrance and exit to the elevated activity period.
    • during periods of highest cortical activity, muscle activity was completely suppressed.
    • peak firing rates were above 100hz! (mean: 12-16hz).


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ref: -2012 tags: Emo Todorov contact invariant animation optimization complex motor behavior date: 05-04-2016 17:34 gmt revision:3 [2] [1] [0] [head]

* Watch the [http://homes.cs.washington.edu/~todorov/index.php?video=MordatchSIGGRAPH12&paper=Mordatch,%20SIGGRAPH%202012 movies! Discovery of complex behaviors through contact-invariant optimization]

  • Complex movements tend to have phases within which the set of active contacts (hands, feet) remains invariant (hence can exert forces on the objects they are contacting, or vice versa).
  • Discovering suitable contact sets is the central goal of optimization in our approach.
    • Once this is done, optimizing the remaining aspects of the movement tends to be relatively straightforward.
    • They do this through axillary scalar variables which indicate whether the a contact is active or not, hence whether to enable contact forces.
      • Allows the optimizer to 'realize' that movements should have phases.
      • Also "shapes the energy landscape to be smoother and better behaved"
  • Initial attempts to make these contact axillary variables discrete -- when and where -- which was easy for humans to specify, but made optimization intractable.
    • Motion between contacts was modeled as a continuous feedback system.
  • Instead, the contact variables c ic_i have to be continuous.
  • Contact forces are active only when c ic_i is 'large'.
    • Hence all potential contacts have to be enumerated in advance.
  • Then, parameterize the end effector (position) and use inverse kinematics to figure out joint angles.
  • Optimization:
    • Break the movement up into a predefined number of phases, equal duration.
    • Interpolate end-effector with splines
    • Physics constraints are 'soft' -- helps the optimizer : 'powerful continuation methods'
      • That is, weight different terms differently in phases of the optimization process.
      • Likewise, appendages are allowed to stretch and intersect, with a smooth cost.
    • Contact-invariant cost penalizes distortion and slip (difference between endpoint and surface, measured normal, and velocity relative to contact point)
      • Contact point is also 'soft' and smooth via distance-normalized weighting.
    • All contact forces are merged into a f 6f \in \mathbb{R}^6 vector, which includes both forces and torques. Hence contact force origin can move within the contact patch, which again makes the optimization smoother.
    • Set τ(q,q˙,q¨)=J(q) Tf+Bu\tau(q, \dot{q}, \ddot{q}) = J(q)^T f + B u where J(q) T J(q)^T maps generalize (endpoint) velocities to contact-point velocities, and f above are the contact-forces. BB is to map control forces uu to the full space.
    • τ(q,q˙,q¨)=M(q)q˙+C(q,q˙)q˙+G(q)\tau(q, \dot{q}, \ddot{q}) = M(q)\dot{q} + C(q, \dot{q})\dot{q} + G(q) -- M is inertia matrix, C is Coriolis matrix, g is gravity.
      • This means: forces need to add to zero. (friction ff + control uu = inertia + coriolis + gravity)
    • Hence need to optimize ff and uu .
      • Use friction-cone approximation for non-grab (feet) contact forces.
    • These are optimized within a quadratic programming framework.
      • LBFGS algo.
      • Squared terms for friction and control, squared penalization for penetrating and slipping on a surface.
    • Phases of optimization (continuation method):
      • L(s)=L CI(s)+L physics(s)+L task(s)+L hint(s)L(s) = L_{CI}(s) + L_{physics}(s) + L_{task}(s) + L_{hint}(s)
      • task term only: wishful thinking.
      • all 4 terms, physcics lessened -- gradually add constraints.
      • all terms, no hint, full physics.
  • Total time to simulate 2-10 minutes per clip (only!)
  • The equations of the paper seem incomplete -- not clear how QP eq fits in with the L(s)L(s) , and how c ic_i fits in with J(q) Tf+BuJ(q)^T f + B u

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ref: Teagarden-2007.03 tags: STN striatum operant conditioning behavior rats 2006 DBS date: 02-15-2012 03:36 gmt revision:5 [4] [3] [2] [1] [0] [head]

PMID-17182916[0] Subthalamic and Striatal Neurons Concurrently Process Motor, Limbic, and Associative Information in Rats Performing an Operant Task

  • STN encodes behavioral events (reinforcement, nose poke, correct / incorrect trials). So does the striatum.
  • This study is rather nonspecific, but it makes sense that a conserved and well connected region is active during learning & general behavior.
    • That is, while the subthalamic nucleus is considered an output relay of the basal ganglia, more likely it operates in parallel to facilitate forms of learning; as such, responses are shown to rewards, cues, etc.


[0] Teagarden MA, Rebec GV, Subthalamic and striatal neurons concurrently process motor, limbic, and associative information in rats performing an operant task.J Neurophysiol 97:3, 2042-58 (2007 Mar)

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ref: Doty-1969.01 tags: Doty microstimulation brain behavior macaque conditioned stimulus attention motivation 1969 date: 12-29-2011 23:28 gmt revision:8 [7] [6] [5] [4] [3] [2] [head]

PMID-4888623[0] Electrical stimulation of the brain in behavioral context.

  • Excellent review.
  • Focal stimulation of macaques can induce insect-grabbing responses, after which they will carefully examine their hands to see what was caught!
    • Same thing has been observed in humans -- the patient reported that he wanted to catch 'that butterfly'.
  • Such complicated action must be the effect of downstream / upstream targets of the stimulated site, as the actual stimulation carries no information other than it's spatial locality within the brain.
  • Stimulation of the rostral thalamus in the language hemisphere can elicit phrases: "Now one goes home", "Thank you", "I see something".
    • These are muttered involuntarily and without recollection of having been spoken.
  • Doty stimulated macaques at 20ua for 500us as a CS in postcentral gyrus (S1?) for a lever press CR, which should (he says)only activate a few dozen neurons.
  • Can elicit mating behaviors in oposums with electrical stimulation of the hypothalamus, but only if another opossum or furry object is present.
  • Stimulation of the caudate nucleus in humans causes an arrest reaction: they may speak, smile, or laught inappropriately, but appropriate voluntary responses are brought to a halt.
  • Stimulation of the basolateral amygdala can cause:
    • Hungry cats to immediately stop eating
    • Stop stalking prey
    • Non-hunting animals to stalk prey, and indeed will solve problems to gain access to rats which can be attacked.
  • Prolonged stimulation of almost every place in the brain of a cat at 3-8Hz can put it to sleep, though since lab cats normally sleep 17/24hours, this result may not be significant.
  • Stimulation at most sites in the limbic system has the still mysterious ability to organize motor activity in any fashion required to produce more of the activity or to avoid it, as the case may be.
  • Rats that are stimulated in the periaqueductal gray will self-administer stimulation, but will squeal and otherwise indicate pain and fright during the stimulation. Increasing the duration of stimulation from 0.5 to 1 second makes self-administration of this apparently fearful stimulation stop in both rats and cats.
  • Certain patterns of activity within systems responsible for fearful or aggressive behavior, rather than being aversive are perversely gratifying. This is clearly recognized in the sociology of man...
  • Rats will self-stimulate with the same stimulus trains that will cause them to eat and drink, and under some conditions the self-stimulation occurs only if food or water is available.
  • On the other hand, rats will choose self-stimulation of the lateral hypothalamus instead of food, even when they are starving.
    • Electrically induced hunger is its own reward.
  • The work of Loucks (124, 125) forms the major point of origin for the concept that motivation is essential to learning. with careful and thorough training, Loucks was unable to form CRs to an auditory CS using stimulation of the motor cortex as the US. With this paradigm, the limb movements elicited by the US never appeared to the CS alone; but movements were readily established when each CS-US combination was immediately followed by the presentation of food.
    • However: Kupalov independently proved that stimulation of the motor cortex could be used as the US, at the same time using stimulation at other loci as the CS.
    • Why the difference? Attention -- failures are commonly obtained with animals that consistenly fidget or fight restraint, as most of them do.
    • Cortical stimulation itself is not rewarding or aversive; animals neither seek nor avoid stimulation of most neocortical areas.
  • On classical conditioning: [Bures and colleagues (20, 65) bibtex:Bures-1968 bibtex:Gerbrandt-1968] found that if an anticedent stimulus, which might or might not effect a neuron, were consistently followed by effective intracellular electrical stimulation of that individual neuron, in roughly 10 percent of the cells of the neocortex, hippocampus, thalamus, or mesencephalic reticular formation a change in the response of that cell to the antecedent stimulus could be observed.
  • With an apparent exception of the cerebellum it is possible to electrical excitation any place in the brain as a CS in chickens, rats, rabbits ...
  • Stimulation of group 1 proprioceptive muscle-afferent fibers in cats is ineffective as a CS.
    • Muscle spindles lack clear access to the systems subserving conditioned reflexes. (These instead go to the cerebellum)
  • Macaques can also discriminate between two stimulation sites 1-3 mm apart apparently over the entirety of the cortex, at frequencies between 2 and 100Hz, and over a 4-10fold range of currents.
  • In human cases where electrical stimulation or the cortex elicits specific memories, extirpation of the stimulated area does not effect recall of this memory (156) {973}.


[0] Doty RW, Electrical stimulation of the brain in behavioral context.Annu Rev Psychol 20no Issue 289-320 (1969)

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ref: De-2007.02 tags: perkinsons REM RBM behavior disorder date: 11-11-2007 05:43 gmt revision:1 [0] [head]

PMID-17235126[0] Restoration of normal motor control in Parkinson's disease during REM sleep.

  • wow! but, hasn't this been known for a while?


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ref: Bair-1996.08 tags: precise spike timing cortex behavior Sejnowski date: 04-09-2007 00:57 gmt revision:0 [head]

PMID-8768391[0] Temporal precision of spike trains in extrastriate cortex of the behaving macaque monkey

  • This temporal modulation is stimulus dependent, being present for highly dynamic random motion but absent when the stimulus translates rigidly -- that is, the response is markedly reproducable and precise to a few milliseconds.

PMID-16339894[1] Neurons of the cerebral cortex exhibit precise interspike timing in correspondence to behavior.

  • in the cortex, spikes can be very precise.
  • this was a slice investigation.

PMID-7770778[2] Reliability of spike timing in neocortical neurons.

  • neocortex of rats
  • suggest low intrinsic noise level in spike generation, allowing accurate transformation of synaptic input into spike generation