Mapping the nerve pathways of the spine: Professor Andrew Todd

Issued: Wed, 26 Jun 2013 15:45:00 BST

Professor Andrew Todd draws on more than 30 years’ research into the spinal cord to examine how nerve pathways are organised to help us to feel sensations like pain and itch, and how the circuits that control these pathways operate. His neuroscience team uses a broad range of techniques including immunocytochemistry and confocal microscopy to investigate what goes on in the spinal dorsal horn in particular.

‘We know that sensory information comes into the spinal cord and is transmitted up to the brain via fairly direct pathways of projection neurons,’ Professor Todd explains. ‘But in among those pathways are enormous numbers of nerve cells – interneurons – which are found in the dorsal horn and serve to regulate or modify the sensory information. The way that these are wired up is extremely complicated and very poorly understood.

‘Part of the reason for that is because we don’t have a very good way of categorising individual nerve cells. So a lot of what we do is to try and classify the cells into functional populations – excitatory and inhibitory – and then we begin to see how those connect up. What we hope to produce is a wiring diagram of how the spinal cord operates, both in terms of the projection neurons that carry information to the brain and the interneurons involved in local control.’

Although Professor Todd’s primary interest is in the normal structure of the dorsal horn, his research could have major implications in terms of advancing our understanding of disease states, especially chronic pain. While acute pain is fairly treatable with standard analgesic drugs, chronic pain – in particular neuropathic pain, which usually results from nerve injury – is very difficult to treat and also fairly common among the population.

‘A number of theories have been put forward about what goes on in nerve injury, one of which is that the inhibitory interneurons that normally control pain are either killed or inactivated,’ says Professor Todd. ‘Our findings don’t support what people have previously reported, and so we think that there isn’t in fact any major change in the arrangement of these inhibitory cells. Even though we’re not directly involved in the development of treatment, we can shed light on the underlying mechanisms that must inform their design.’

As well as collaborating to varying extents with other spinal cord experts around the world, Professor Todd’s team welcomes a steady stream of PhD students from the UK and overseas. ‘We have a really international lab,’ he says. ‘Typically, we each have between one and three postgraduate students at any one time. The University’s scientific expertise is very highly rated and students are well looked after in terms of supervision. Glasgow’s graduate school is very well organised, and the general feeling is that it is a popular place to be.’