Effect of different spinal cord lesions on visually guided switching of target-reaching in cats.
It has previously been shown that when a target is moved, cats can change the direction of ongoing target-reaching with brief latency suggesting a tectal relay. Switching of target-reaching has now been investigated after spinal lesions: (1) dorsally in C5 interrupting cortico- (CS) and rubrospinal (RS) fibres to forelimb segments; (2) more ventrally in C5 interrupting axons of the C3-C4 propriospinal neurones (PNs) to forelimb motoneurones; and (3) ventrally in C2 interrupting tectospinal and tecto-reticulospinal fibres. Short-latency switching of target-reaching remained after lesions 1 and 2. A subsequent lesion 3 after lesion 1 or 2 prolonged the switching latency. The results show that fast switching, presumably relayed in tectum, can be made when the cat utilizes C3-C4 PNs or interneurones in the forelimb segments for target-reaching. For both neuronal systems, the longer-latency switching after ventral C2 lesion is assumed to be cortically relayed and mediated by the CS and RS tracts.
Alstermark
B
B
Department of Physiology, University of Göteborg, Sweden.
Górska
T
T
Lundberg
A
A
Pettersson
L G
LG
Walkowska
M
M
D000818:Animals; D002415:Cats; D003216:Conditioning, Operant; D005552:Forelimb / Q000294:innervation; D007395:Interneurons / Q000502:physiology; D010775:Photic Stimulation; D013116:Spinal Cord / Q000502:physiology*; D013477:Superior Colliculi / Q000502:physiology; D014785:Vision, Ocular