Hippocampal kindling leads to motor map expansion.
OBJECTIVE
To determine whether seizure activity, repeatedly elicited in the hippocampus, could alter the functional organization of neocortical movement representations (motor maps) and whether a relation exists between the number of afterdischarges recorded in the sensorimotor neocortex and the size of the motor maps.


METHODS
We electrically kindled the right ventral hippocampus of Long-Evans hooded rats, twice daily, for 40 sessions and recorded the afterdischarges in the stimulated hippocampus and right sensorimotor neocortex. Between 3 and 7 days after the last seizure, we used high-resolution intracortical microstimulation to derive the forelimb-movement representations in the left (un-implanted) sensorimotor neocortex.


RESULTS
In the hippocampal kindled rats, we observed a dramatic expansion of the area of neocortex that would elicit forelimb movements compared with sham-kindled controls. The number of afterdischarges recorded in the neocortex was significantly and positively correlated with the size of the motor maps.


CONCLUSIONS
Seizures propagating from the hippocampus have long-distance effects on the functional organization of motor maps.
van Rooyen
Francine
F
Behavioural Neuroscience Research Group, Department of Psychology, and Calgary Epilepsy Program, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.
Young
Nicole A
NA
Larson
Sarah E M
SE
Teskey
G Campbell
GC
D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D001931:Brain Mapping; D004195:Disease Models, Animal; D004558:Electric Stimulation; D004567:Electrodes, Implanted; D004569:Electroencephalography / Q000706:statistics & numerical data*; D005552:Forelimb / Q000502:physiology; D006624:Hippocampus / Q000503:physiopathology; D007696:Kindling, Neurologic / Q000502:physiology*; D008297:Male; D008839:Microelectrodes; D009044:Motor Cortex / Q000503:physiopathology*; D009068:Movement / Q000502:physiology; D019579:Neocortex / Q000503:physiopathology*; D009434:Neural Pathways / Q000503:physiopathology; D051381:Rats; D020318:Rats, Long-Evans; D012640:Seizures / Q000209:etiology / Q000503:physiopathology*