MRC National Institute for Medical Research, London
Science for Health
2007 meeting - Deconstructing the nervous system
To the uninitiated the nervous system seems impossibly complicated with an organisation that almost defies description, with billions of neurons and an astonishing range of functional capacities and yet scientists make steady and often spectacular progress in understanding these formidable problems. Our presentations concern two topics in this field, to which staff of NIMR have made major contributions, memory and the understanding of spinal injuries
What is the physical basis of memory?
Man's capacity to remember - in some cases for a hundred years - is one of the greatest wonders of the living world; the loss of this faculty in old age, one of the biggest challenges to biomedical science. As a young scientist, Dr Bliss made a seminal contribution to understanding memory when he showed that electrical stimuli to a particular region of the rodent brain left a trace that could be measured as an increase in the efficiency of nerve transmission for a long time after stimulation had ceased. This region, the hippocampus, was already a suspected seat of memory. A plausible hypothesis was that the physical basis of memory was to be found in this ability of the hippocampus to store prior activity as long-lasting increases in the efficiency with which neural activity was transmitted across connections between hippocampal neurons. In the intervening years, Tim, with a vast web of collaborators has refined and extended this idea so that we now know about many aspects of how nerve cells in the brain store memories, and about some of the proteins and small molecules that help to carry out the task.
Looking for ways to repair spinal injuries
The mammalian body has a well-established capacity to repair severed peripheral nerves that is exploited when doctors treat a damaged limb. For spinal nerve injuries, the prognosis is extremely grave; these nerves seem to have no capacity to regenerate in a useful fashion and the victim is usually paralysed. However, a deep knowledge of neuroanatomy has led Professor Raisman to the conclusion that this is not an "iron law". He invested his hopes in an obscure observation that suggested that neurones that connect organs of smell to the brain retain a capacity to repair once severed. This capacity, more characteristic of an embryo than an adult tissue, is conferred by cells that form a sheath around nerve cells (Schwann cells). Geoff has shown that these cells, when introduced into spinal injuries of rodents, encourage repair of spinal nerves and allow the experimental animals to regain mobility. The stage is now set for clinical trials at UCL in which attempts will be made to repair human spinal lesions using ideas arising from this research.
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