Lesions of Area 5 of the Posterior Parietal Cortex in the Cat Produce Errors in the Accuracy of Paw Placement During Visually Guided Locomotion

Abstract

We developed a novel locomotor task in which cats step over obstacles that move at a different speed from that of the treadmill on which the cat is walking: we refer to this as a visual dissociation locomotion task. Slowing the speed of the obstacle with respect to that of the treadmill sometimes led to a major change in strategy so that cats made two steps with the hindlimbs before stepping over the obstacle (double step strategy) instead of the single step (standard strategy) observed when the obstacle was at the same speed as the treadmill. In addition, in the step preceding the step over the obstacle, the paws were placed significantly closer to the obstacle in the visual dissociation task than when the treadmill and the obstacle were at the same speed. After unilateral lesion of area 5 of the posterior parietal cortex (PPC), the cats frequently hit the obstacle as they stepped over it, especially in the visual dissociation task. This locomotor deficit was linked to significant differences in the location in which the forelimbs were placed in the step preceding that over the obstacle compared with the prelesion control. Cats also frequently hit the obstacle with their hindlimbs even when the forelimbs negotiated the obstacle successfully; this suggests an important role for the posterior parietal cortex in the coordination of the forelimbs and hindlimbs. Together, these results suggest an important contribution of the PPC to the planning of visually guided gait modifications.

Prism adaptation and generalization during visually guided locomotor tasks

“…The absence of aftereffects in these same measures is likely due to this lack of adaptation. The fact that step N-1 did not adapt during the obstacle task was surprising given that foot placement before the obstacle is critical for obstacle clearance since it is largely responsible for the success of the movement (Patla and Greig 2006;Lajoie and Drew 2007). However, there was no specific target to step to, and so there was less certainty of any error in foot placement to drive a subsequent adaptation.…”

“…Neurons in the PPC have been found to discharge during locomotion in the cat (Andujar et al 2010;Beloozerova and Sirtoa 2003;Drew and Marigold 2008). It has been argued that their function is in the motor planning and execution of gait modifications (Marigold et al 2011), particularly related to placement of the limb (Beloozerova and Sirota 2003;Lajoie and Drew 2007) and to online corrections (Drew and Marigold 2008) similar to reaching (Pisella et al 2000).…”

Substrates for normal gait and pathophysiology of gait disturbances with respect to the basal ganglia dysfunction

“…These findings suggest that sensory inputs that signal context -the visual and auditory environment that surrounds an animal -play an important role in shaping the basic pattern of locomotion. Lajoie and Drew [23] observed, after unilateral lesion of area 5 of the posterior parietal cortex, that cats frequently hit the obstacle as they stepped over it. Cats also frequently hit the obstacle with their hindlimbs even when the forelimbs negotiated the obstacle successfully.…”

Effects of Gait Variations on Grip Force Coordination During Object Transport

“…The posterior parietal cortex could be ascribed a key role in this process, given its activity during tasks requiring higher-level somatosensory processes (for review, see Andersen and Buneo 2002), movement planning (e.g., Fernandez-Ruiz et al 2007), and visually guided gait modifications (Lajoie and Drew 2007). Posterior parietal regions also demonstrated importance in varying limb postures (Pellijeff et al 2006), dual-task performance (Mochizuki et al 2007), and single isolated actions versus repetitive automated ones (Schaal et al 2004).…”