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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: 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}.

____References____

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