Projects

Spinal Cord Laboratory Current Projects

Lab Head: Dr Peter Kirkwood

Spinal Cord Injury
 

There are two parallel themes to current work in the lab. The first is the use of the bulbospinal neurones to gain understanding of the neuronal processes underlying the functional improvement seen in experimental spinal cord repair. Considerable success has been achieved in a number of laboratories in achieving regeneration of central nerve fibres across or through lesions of the spinal cord. In the same animals a degree of behaviourally defined functional recovery is also often demonstrated, yet a direct causal causal link has generally not been established between these two phenomena. Using expiratory bulbospinal neurones as an example of 'upper motor neurons' which have well-identified direct connections to motoneurones, we are asking whether, in the context of regeneration in adult animals, their axons will make connections with the same specificity as during normal development (e.g. connections to motoneurones being mostly to motoneurones innervating expiratory muscles). Previously we have investigating changes in these connections to both motoneurones and interneurones that may occur in the segment above a chronic spinal lesion which interrupts the bulbospinal axons, as well as morphological changes in the interneurones themselves. Secondly, we are using combinations of electrophysiological and anatomical techniques to study the synaptic actions of rubrospinal and corticospinal tracts and their plasticity following lesions of the cervical spinal cord. Changes in the performance of the animals in behavioural tasks are measured in parallel, to allow correlation of these changes with the physiological and anatomical measurements.

Persistent inward currents and the respiratory drive

Persistent inward currents are believed to be an important cellular mechanism in motoneurones, whereby synaptic currents are amplified sufficiently to produce a vigourous motoneurone discharge. The extent to which this occurs in naturally evoked motor acts is unclear (Heckman et al. 2005, Muscle & Nerve 31 : 135-156), but the respiratory drive provides a useful central derived natural input for which this can be studied. In collaboration with Professor Hans Hultborn ( University of Copenhagen ), we are investigating the role of such currents in phrenic and limb motoneurones.