Article

Rodents are the primary animal model of corticospinal injury and
repair, yet current behavioral tests do not show the large deficits after injury
observed in humans. Forearm supination is critical for hand function and is
highly impaired by corticospinal injury in both humans and rats. Current tests of
rodent forelimb function do not measure this movement. OBJECTIVE: To determine if
quantification of forelimb supination in rats reveals large-scale functional loss
and partial recovery after corticospinal injury. METHODS: We developed a knob
supination device that quantifies supination using automated and objective
methods. Rats in a reaching box have to grasp and turn a knob in supination in
order to receive a food reward. Performance on this task and the single pellet
reaching task were measured before and after 2 manipulations of the pyramidal
tract: a cut lesion of 1 pyramid and inactivation of motor cortex using 2
different drug doses. RESULTS: A cut lesion of the corticospinal tract produced a
large deficit in supination. In contrast, there was no change in pellet retrieval
success. Supination function recovered partially over 6 weeks after injury, and a
large deficit remained. Motor cortex inactivation produced a dose-dependent loss
of knob supination; the effect on pellet reaching was more subtle. CONCLUSIONS:
The knob supination task reveals in rodents 3 signature hand function changes
observed in humans with corticospinal injury: (1) large-scale loss with injury,
(2) partial recovery in the weeks after injury, and (3) loss proportional to
degree of dysfunction.

Langue : ANGLAIS