Conditioning pp 651-661 | Cite as

Plasticity, Experience and Resource Allocation in Motor Cortex and Hypothalamus

  • D. Nico Spinelli
  • Frances E. Jensen
Part of the Advances in Behavioral Biology book series (ABBI, volume 26)


Training kittens to avoid an “unsafe” visual stimulus by flexing one forearm has major effects on visual and somatic cortex adult organization (4). Here we show that two important interfaces to the world, motor cortex and the hypothalamus, are similarly affected. Punctuate stimulation of the motor cortex reveals a four-fold increase in the diameter of the area allocated to the control movement of the trained forearm relative to the untrained one. Some of the motor responses in the animals resembled elementary movements in comprising correct responses during training. Cellular responses in the hypothalamus showed a shift toward cells with selectivity for the trained forearm; some of these cells showed the additional characteristic of selective responsivity to the visual stimuli used in training. It appears that the partitioning of the motor cortex and the repertoire of responses available to it are substantially influenced by early experience. The access that sensory stimuli have to the hypothalamus is also modified, possibly changing the way in which the adult will later cope with demanding tasks. The results dramatically demonstrate that simple early experience exerts widespread effect on structures which will later prove critical in setting the limits of individual potential.

We have recently demonstrated that if an unusually large amount of information is presented to a patch of skin on one side of the body during development, a reallocation of resources takes place in somatosensory cortex such that the cortical area allocated to that patch of skin becomes many times larger than normal.

We have also shown that in this cortical area dendritic branching (1) and bundling (2) are considerably greater than in the corresponding area in the contralateral hemisphere where the untrained forearm is represented.

The procedure we used to bring about these changes consisted of a simple avoidance procedure in which a “safe” or an “unsafe” visual stimuli was presented to a kitten through goggles and the kitten was required to flex one of the forelegs to the “unsafe” stimulus or receive a mild shock on that foreleg. Such a discrete response was chosen to facilitate investigating the effect of the training on motor cortex to determine if a reallocation similar to that in somatosensory cortex had occurred. Penfield and others (3) have shown that parts of the body which have greater sensory and motor sophistication have larger cortical representations in general.

We show in this report that early experience has a significant effect on the final size of the representation areas within the motor cortex. Further, while the brain interacts with the outside world through the motor system, it exercises control over the internal milieu through an interface which is largely contained within the hypothalamus. We also show in this report that in the hypothalamus polymodal responses to visual and somatic stimuli have been modified in accordance to the stimuli used during training.


Motor Cortex Cortical Area Somatosensory Cortex Cortical Stimulation Internal Milieu 


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  1. 1.
    D. N. Spinelli, F. E. Jensen, and G. Viana Di Prisco. Early Experience effect on dendritic branching on normally reared kittens. Experi. Neurol. Vol. 68, No. 1, 1980.Google Scholar
  2. 2.
    F. E. Jensen and D. N. Spinelli. Early experience effect on dendritic bundles. Society for Neuroscience Abstracts, Vol. 5, 1979.Google Scholar
  3. 3.
    For example, W. G. Penfield and E. Boldrey. Somatic motor and sensory representation in the cerebral cortex of amn as studied by electrical stimulation. Brain 60: 389, 1937; C. N. Woolsey and D. Fairman. Contralateral, ipsalateral and bilateral representations of cutaneous receptors in somatic areas I and II of the cerebral cortex of pig, sheep, and other animals. Surgery 19: 684, 1946; C. N. Woolsey. Organization of somatic sensory and motor areas of the cerebral cortex. In H. F. Harlow and C. N. Woolsey (Eds.) Biological and biochemical bases of behavior. Madison, 1958, Univ. of Wisc. Press; and L. I. Malls, K. H. Pribran and L. Kruger. Action potentials in “motor” cortex evoked by peripheral nerve stimulation. J. Neurophysiol. 16: 161, 1953.Google Scholar
  4. 4.
    D. N.. Spinelli and F. E. Jensen. Plasticity: The mirror of experience. Science 203: 75–79, 1979.Google Scholar
  5. 5.
    A. M. Wyss and S. Obrador. Adequate shape and rate of stimuli in electrical stimulation of the cerebral motor cortex. Am. J. Physiol. 120: 42, 1937.Google Scholar
  6. 6.
    C. Cure and T. Rasmussen. Effects of altering parameters electrical stimulating currents upon motor responses from precentral gyrus of the Macaca mulatta. Brain 77: 18, 1954.Google Scholar
  7. 7.
    The rationale for bipolar stimulation is that in this case the current propagation path is between the tubing and the inner core and produces the least current spread. Because the current path is localized on the surface of the cortex, stimulation is of decreased intensity in the deeper cortical layers. In the monopolar condition, there is probably better conduction to the deeper layers. In the monopolar condition, there is probably better conduction to the deeper layers but current spread is greater and stimulus localization is dependent upon careful adjustment of current intensities so that the current should exceed threshold only in close proximity of the electrode tip.Google Scholar
  8. 8.
    E. V. Evarts. Feedback and corollary discharge: A merging of concepts. Neurosci. Res. Program Bull. 9: 86, 1971.Google Scholar
  9. 9.
    D. N. Spinelli, H. V. B. Hirsch, R. W. Phelps, and J. Metzler. Visual experience as a determinant of the response characteristics of cortical receptive fields in cats. Exp. Brain Res. 15: 289, 1972.Google Scholar
  10. 10.
    W. G. Penfield and E. Boldrey. Somatic motor and sensory representation in the cerebral cortex of man as studied by electrical stimulation. Brain 60: 389, 1937.Google Scholar
  11. 11.
    For example, J. V. Brady, Ulcers in “executive” monkeys. Sci. Amer. 199: 95, 1958; and W. J. H. Nauta, (Eds.) The Hypothalamus. Springfield, Ill., 1969, C. C. Thomas, publisher.Google Scholar
  12. 12.
    In fact, the work of Penfield has shown similar phenomena of variation in humans even though lack of developmental data makes it impossible to determine the relative contribution of early experience of each subject, as can be seen from the following: The (cortical representational) fields…overlap each other because of the great variability in individual cases. If arm and hand extend unusually high, then the lower extremity may have its representation only in the fissure,“ from Epilepsy and CerebralLocalization by Wilder, Penfield, and P. C. Ericson, (Eds.) Springfield, Ill., 1941 p. 45, C. C. Thomas, Publisher.Google Scholar
  13. 13.
    R. S. Snider and W. T. Niemer. A Stereotaxic Atlas of the Cat Brain. Third Printing. Chicago, Ill., 1970, Univ. of Chicago Press.Google Scholar

Copyright information

© Springer Science+Business Media New York 1982

Authors and Affiliations

  • D. Nico Spinelli
    • 1
  • Frances E. Jensen
    • 1
  1. 1.Departments of Computer and Information Science and PsychologyUniversity of MassachusettsAmherstUSA

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