Characterisation and functional mapping of surface potentials in the rat dorsal column nuclei.
The brainstem dorsal column nuclei (DCN) process sensory information arising from the body before it reaches the brain and becomes conscious. Despite significant investigations into sensory coding in peripheral nerves and the somatosensory cortex, little is known about how sensory information arising from the periphery is represented in the DCN. Following stimulation of hind-limb nerves, we mapped and characterised the evoked electrical signatures across the DCN surface. We show that evoked responses recorded from the DCN surface are highly reproducible and are unique to nerves carrying specific sensory information.



The brainstem dorsal column nuclei (DCN) play a role in early processing of somatosensory information arising from a variety of functionally distinct peripheral structures, before being transmitted to the cortex via the thalamus. To improve our understanding of how sensory information is represented by the DCN, we characterised and mapped low- (<200 Hz) and high-frequency (550-3300 Hz) components of nerve-evoked DCN surface potentials. DCN surface potentials were evoked by electrical stimulation of the left and right nerves innervating cutaneous structures (sural nerve), or a mix of cutaneous and deep structures (peroneal nerve), in 8-week-old urethane-anaesthetised male Wistar rats. Peroneal nerve-evoked DCN responses demonstrated low-frequency events with significantly longer durations, more high-frequency events and larger magnitudes compared to responses evoked from sural nerve stimulation. Hotspots of low- and high-frequency DCN activity were found ipsilateral to stimulated nerves but were not symmetrically organised. In conclusion, we find that sensory inputs from peripheral nerves evoke unique and characteristic DCN activity patterns that are highly reproducible both within and across animals.
The Eccles Institute of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital Territory, 2601, Australia.|School of Medical Sciences, University of New South Wales, Sydney, New South Wales, 2052, Australia.
Alastair J
AJ
Loutit
The Eccles Institute of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital Territory, 2601, Australia.
Ted
T
Maddess
Graduate School of Biomedical Engineering, University of New South Wales, Sydney, New South Wales, 2052, Australia.
Stephen J
SJ
Redmond
School of Medicine, Western Sydney University, Sydney, New South Wales, 2560, Australia.|School of Medical Sciences, University of New South Wales, Sydney, New South Wales, 2052, Australia.
John W
JW
Morley
The Eccles Institute of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital Territory, 2601, Australia.
Greg J
GJ
Stuart
The Eccles Institute of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital Territory, 2601, Australia.|School of Medical Sciences, University of New South Wales, Sydney, New South Wales, 2052, Australia.|ANU Medical School, Australian National University, Canberra, Australian Capital Territory, 2601, Australia.
Jason R
0000-0002-1973-8211
JR
Potas
D000818:Animals; D001931:Brain Mapping; D001933:Brain Stem / Q000502:physiology*; D005073:Evoked Potentials, Somatosensory; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012584:Sciatic Nerve / Q000502:physiology
dorsal column nucleus; peroneal nerve; somatosensation; sural nerve; surface potential