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[0] Sabelli HC, Mosnaim AD, Vazquez AJ, Giardina WJ, Borison RL, Pedemonte WA, Biochemical plasticity of synaptic transmission: a critical review of Dale's Principle.Biol Psychiatry 11:4, 481-524 (1976 Aug)[1] Sulzer D, Rayport S, Dale's principle and glutamate corelease from ventral midbrain dopamine neurons.Amino Acids 19:1, 45-52 (2000)[2] Burnstock G, Do some nerve cells release more than one transmitter?Neuroscience 1:4, 239-48 (1976 Aug)

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ref: Hagbarth-1983.02 tags: piper rhythm oscillations feedback proprioception spinal reflex date: 01-19-2012 21:41 gmt revision:2 [1] [0] [head]

PMID-6869036[0] The Piper rhythm--a phenomenon related to muscle resonance characteristics?

  • Piper rhythm: the tendency towards rhytmical 40-60 Hz grouping of motor unit potentials in steadily contracting human muscles.
  • Recording of nerves in muscles did not support the idea that the Piper rhythm is dependent on afferent spindle pulses causing reflex entrainment. (loop too slow).
  • TThis wouldn't make sense anyway, as the same rhythm appears in different muscles with markedly different mechanical properties.
  • Likkely cause is the cerebrum, upper oscillations. Interesting!
  • See also: PMID-9862895[1] Cortical correlate of the Piper rhythm in humans.
    • MEG data is consistent with the cortex being the origin of the Piper rhythm.
  • And PMID-10203308[2] Rhythmical corticomotor communication.
    • The rhythmic modulation may form a tool for efficient driving of motor units but we express some reservations about the assumed binding and attention-related roles of the rolandic brain rhythms.
  • PMID-10622378[3] Cortical drives to human muscle: the Piper and related rhythms.
    • Alternately, oscillations may be a form of holding state.
    • They think gamma frequencies are a means of binding together simultaneously activated isometric muscles.
    • Inadequate output from the basal ganglia leads to a disappearance of the beta and piper drives to muscle.
    • Did we see and piper band osc activity? Did not look.

____References____

[0] Hagbarth KE, Jessop J, Eklund G, Wallin EU, The Piper rhythm--a phenomenon related to muscle resonance characteristics?Acta Physiol Scand 117:2, 263-71 (1983 Feb)
[1] Brown P, Salenius S, Rothwell JC, Hari R, Cortical correlate of the Piper rhythm in humans.J Neurophysiol 80:6, 2911-7 (1998 Dec)
[2] Hari R, Salenius S, Rhythmical corticomotor communication.Neuroreport 10:2, R1-10 (1999 Feb 5)
[3] Brown P, Cortical drives to human muscle: the Piper and related rhythms.Prog Neurobiol 60:1, 97-108 (2000 Jan)

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ref: Doty-1956 tags: Doty 1958 conditioned reflexes stimulation date: 01-03-2012 07:05 gmt revision:6 [5] [4] [3] [2] [1] [0] [head]

PMID-13367871[0] Conditioned reflexes established to electrical stimulation of cat cerebral cortex.

  • One sentence: used ICMS to act as a CS for a CR (shock-avoidance) in cats. Not really ICMS, as electrodes were placed on the surface.
  • They suggest ICMS is a means for probing the cortex without going through that trouble and complex transform of the sensory nerves and PNS.
    • If only. ICMS is complex enough.
  • Loucks [6,7,8] used a buried induction coil! Have things advanced all that much? (They bring this up in that magnetic stimulation of the induction coil induces vibration, which the animal can feel.)
  • Use 'vitalium' screws to fix their plexiglas encased platinum wire electrode to the scull.
    • Relatively large electrodes, not in the cortex but resting upon it -- this is why the current was relatively high.
  • Monophasic ICMS, 50Hz, 2ms, 2 sec train, 4-6V (not current controlled).
    • Fixed this by putting a 10k resistor in series and recording current across that. approx 700uA stimulation current -- high!
  • Most of the cortex worked as a CS: stimulation of points distributed throughout the marginal, postlateral, middle suprasylvian, and middle and posterior ectosylvian gyri (Fig. 2).
  • Observed a narrow threshold for conditioning responses, e.g. 0.35mA would give only 1/5 correct, 0.45 4/5 correct.
  • Dura excised in these surgeries, since any stimulation of the dura is painful.
    • To control for this, they severed the trigeminal nerve.
  • gave strength / duration curves. (remember, monopolar).
  • deinervated the animals as control -- could feel nothing but the current delivered to their head!
  • Other controls: Loucks (7) showed that CR persisted with stimulation to the motor cortex after the limb that moved upon superthreshold stimulation was paralyzed.
  • "The present experiments fully confirm the thesis that CRs to cortical stimulation are in no way dependent on detectable motor effects."
  • Animals can also discriminate one frequency from another (30Hz vs 100Hz). Verified by Romo, much later.

____References____

[0] DOTY RW, LARSEN RM, RUTHLEDGE LT Jr, Conditioned reflexes established to electrical stimulation of cat cerebral cortex.J Neurophysiol 19:5, 401-15 (1956 Sep)

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ref: Sabelli-1976.08 tags: anatomy of the spinal cord interneurons pyramidal tract commissure reflexes date: 04-23-2007 05:12 gmt revision:1 [0] [head]

Anatomy of the spinal cord

  • wow! detailed!!
  • the spinal cord is remarkably complex (of course, considering how old it is and how important it is for structuring movement and locomotion..well..most animals)
  • there is a lot of well-organized circuitry in the spinal cord mediating adaptive phenomena and reflexes like the clasp knife reflex (upper motoneuron disease where the resistance to flexion abruptly melts away when the joint is fully flexed)

____References____

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ref: bookmark-0 tags: ISO learning reflex inverse controller Porr date: 0-0-2007 0:0 revision:0 [head]

Iso learning approximates a solution to the inverse controller problem in an usupervised behavioral paradigm http://hardm.ath.cx/pdf/isolearning2002.pdf

  1. robot/actor whatever has a reflex after the presentation of a reward.
  2. the ISO learning mechanism learns to expect its own reflex -> anticipate actions, react at an appropriate time.
    1. a fixed reflex loop prevents arbitraryness by defining initial behavioral goal.
  3. iso means isotropic: all inputs are the same, and all can be used for learning.
  4. learning is proportional to the derivative of the output.
--
  • the central advantage of an (ideal) feed-forward controller is that it acts without the feedback-induced delay. The fatally damaging sluggishness of feedback systems makes this a highly desirable feature.
  • see figure 4 in the local paper. this basically looks like the cerebellum.. sorta. the controller takes predictive signal, and with this prior information, is able to learn the correct response to the disturbance.
  • they also include an interesting comparison to Sutton & Barto's reinforcement learning:
    • in ISO learning, the weights stabilize if a particular input condition is achieved;
    • in reinforcement learning, the weights are stabilized when a certain output condition is reached.