A horizontal slice preparation for examining the functional connectivity of dorsal column fibres in mouse spinal cord

In spinal cord injury (SCI) research, axon regeneration across spinal lesions is most often assessed using anatomical methods. It would be extremely advantageous, however, to examine the functional synaptic connectivity of regenerating fibres, using high-resolution electrophysiological methods. We have therefore developed a mouse horizontal spinal cord slice preparation that permits detailed analysis of evoked dorsal column (DCol) synaptic inputs on spinal neurons, using whole-cell patch clamp electrophysiology. This preparation allows us to characterise postsynaptic currents and potentials in response to electrical stimulation of DCol fibres, along with the intrinsic properties of spinal neurons. In addition, we demonstrate that low magnification calcium imaging can be used effectively to survey the spread of excitation from DCol stimulation in horizontal slices. This preparation is a potentially valuable tool for SCI research where confirmation of regenerated, functional synapses across a spinal lesion is critical.

• Longitudinally orientated spinal fibres, including those in the dorsal columns, are preserved in acute horizontal slices of mouse spinal cord. • Dorsal column stimulation combined with whole-cell patch clamp electrophysiology allows detailed analysis of dorsal column synaptic inputs. • Low magnification calcium imaging can be used to study the spread of dorsal column evoked excitation in horizontal slices. • This preparation may be useful in identifying functionally regenerated synaptic connections in spinal cord injury models.