Larger cortical motor maps after seizures

Authors

  • Amy K. Henderson,

    1. Hotchkiss Brain Institute, University of Calgary, 3330 Hospital Dr. N.W. Calgary, Alberta, Canada, T2N 4N1
    2. Department of Psychology, University of Calgary, Alberta, Canada
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  • Michael A. Galic,

    1. Hotchkiss Brain Institute, University of Calgary, 3330 Hospital Dr. N.W. Calgary, Alberta, Canada, T2N 4N1
    2. Department of Physiology & Pharmacology, University of Calgary, Alberta, Canada
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  • Karim Fouad,

    1. Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Alberta, Canada
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  • Richard H. Dyck,

    1. Hotchkiss Brain Institute, University of Calgary, 3330 Hospital Dr. N.W. Calgary, Alberta, Canada, T2N 4N1
    2. Department of Psychology, University of Calgary, Alberta, Canada
    3. Department of Cell Biology and Anatomy, University of Calgary, Alberta, Canada
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  • Quentin J. Pittman,

    1. Hotchkiss Brain Institute, University of Calgary, 3330 Hospital Dr. N.W. Calgary, Alberta, Canada, T2N 4N1
    2. Department of Physiology & Pharmacology, University of Calgary, Alberta, Canada
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  • G. Campbell Teskey

    1. Hotchkiss Brain Institute, University of Calgary, 3330 Hospital Dr. N.W. Calgary, Alberta, Canada, T2N 4N1
    2. Department of Psychology, University of Calgary, Alberta, Canada
    3. Department of Physiology & Pharmacology, University of Calgary, Alberta, Canada
    4. Department of Cell Biology and Anatomy, University of Calgary, Alberta, Canada
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Dr. G. Campbell Teskey, as above.
E-mail: gteskey@ucalgary.ca

Abstract

Expansion of motor maps occurs in both clinical populations with epilepsy and in experimental models of epilepsy when the frontal lobes are involved. We have previously shown that the forelimb area of the motor cortex undergoes extensive enlargement after seizures, although the extent to which many movement representation areas are altered is not clear. Here we hypothesize that movement representations in addition to the forelimb area will be enlarged after cortical seizures. To test our hypotheses, Long Evans Hooded rats received 20 sessions of callosal (or sham) kindling, and then were subjected to intracortical microstimulation to map several movement representations including the jaw, neck, forelimb, hindlimb, trunk and tail. We found significantly larger total map areas of several movement representations, including movements that could be evoked more posterior than they are in control rats. We also show the presence of more multiple movement sites and lower movement thresholds in kindled rats, suggesting that movements not only overlap and share cortical territory after seizures, but become present in formerly non-responsive sites as they become detectable with our intracortical microstimulation methodology. In summary, several motor map areas become larger after seizures, which may contribute to the interictal motor disturbances that have been documented in patients with epilepsy.

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