Instrumental Learning Within the Rat Spinal Cord: Localization of the Essential Neural Circuit.

Abstract

Following spinal transection of the upper thoracic spinal cord, male Sprague-Dawley rats given legshock whenever a hindlimb is extended learn to maintain the leg in a flexed position. The region of the cord that mediates this instrumental learning was isolated using neuroanatomical tracing, localized infusion of lidocaine, and surgical transections. DiI and Fluoro-Gold microinjection at the site of shock application labeled motor neuron bodies of lamina IX in the lower lumbar region. Local application of the Na-super++ channel blocker lidocaine disrupted learning when it was applied over a region extending from the lower lumbar (L3) to upper sacral (S2) cord. The drug had no effect rostral or caudal to this region. Surgical transections as low as L4 had no effect on learning. Learning also survived a dual transection at L4 and S3, but not L4 and S2. The results suggest that the essential neural circuit lies between L4 and S3.

Two chronic motor training paradigms differentially influence acute instrumental learning in spinally transected rats

“…Although less is known about the spinal circuits involved in the acquisition of the instrumental response, it presumably involved the activation of nociceptive circuitry, as opposed to propriospinal or cutaneous afferents. It is also known that the L4-S2 spinal cord segments are required for successful instrumental learning because transection or the local application of lidocaine within these segments disrupts learning [30]. Furthermore, instrumental learning depends on temporal contiguity between the response (limb position) and shock onset [25].…”

Syndromics: A Bioinformatics Approach for Neurotrauma Research

“…For example, in the SCI literature, it has been well established that there is plasticity and functional reorganization below a complete transection (117, 124–131). With training, the spinal cord is capable of learning a variety of motor tasks, including Pavlovian associations (132–136), instrumental learning (129, 131, 137–141) and stepping on a treadmill (124, 125, 142–146). This capacity for use-dependent plasticity in the spinal cord has been shown to rely upon propriospinal tract relays (124) and glutamate receptor-mediated plasticity in the lumbar cord (147, 148).…”

Method for studying behavioural activity patterns during long-term recordings using a force-plate actometer

“…performance and stereotypes) are studied in acute tests using short-term records (i.e. testing sessions lasting minutes or hours) to characterise, among other aspect, learning (Liu et al, 2005;Mizuno et al, 2004;Roitman et al, 2005) and drug psychopharmacology (Ali et al, 1995;Cabib et al, 2000;Wolansky and Azcurra, 2005). Both temporal and spatial characteristics of motion must be considered when studying patterns of motor behaviour, which are structured as assumed by several different experimental approaches (Brodkin and motion, namely a force-plate actometer , was designed to substantially improve the spatiotemporal resolution for detecting behavioural detail.…”