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Are axons leading us up the garden path?
TINS - March 1980
IV a~tt/mstd~om p~,e H
the problems of developing a drug distribution and dispensing network could be avoided. However, the advantages offered by existing traditional systems are not purely economic ones. Herbal medicines provide an important component of many of these ancient forms of health care. With the dawning of the age of synthetic drugs, many scientists in the world have been quick to forget that their science was founded on experiments with crude plant and animal extracts. With the realization that the vast majority of herbal medicines were effective some, however, have now turned back to plants in the hope of discovering novel bases for pharmaceutical products. The massive screening programmes for anticancer and antifertility d ~ g s serve as good examples of this current trend. Part of the apparent success of the traditional doctor may simply stem from their treatment of illness at the level of the individual, automatically taking into account the cultural and socioeconomic background to disease symptoms. In this area in particular traditional doctors, perhaps, are in advance of their Western counterparts, particularly in the case of the treatment of mental disorders. In addition to herbal remedies, meditation, induction of trances, body contact, dancing and rituals are all used in the treatment of what we would call mental illness 2. How do these remedies work? In many cases the medicinal herbs used by healers contain psychoactive components, as is the case of the Rauwolfia alkaloids, widely used in Asia and Africa. Other techniques are more difficult to evaluate, but their short-term effects are almost always striking. Acute psychoses are calmed, family disputes resolved, and hysteria disappears. The long-term effects are more difficult to assess. In Thailand, for! example, Buddhist monks treat opium addicts using herbal concoctions which act as powerful emetics. These, however, seem unlikely to be of direct physiological importance, and are instead probably more important as components of a powerful social and spiritual psychotherapy. If these methods are indeed as effective as some~ claim them to be, then the success of these ~ primitive 'health services' may provide some insights into the failings of our own.
Are axons leading us up the garden path? The second annual Quiche Conference supported by the Brain Research Association and the Company of Biologists and organized by the ebullient Vicky Sterling and colleagues, attracted 120 participants to a one-day meeting on 30 November at N.I.M.R., London, to discuss factors controlling the growth o f axons. The morning session was concerned with in vitro studies. Dennis Bray (King's College, London) presented an attractive explanation for growth cone dynamics. He suggests that the generation and movement of a growth cone across a plane surface is dictated by the compound effect of the tensions generated in each of its processes. Graham Dunn (Strangeways) discussed the patterns generated by fibroblasts. Under some experimental conditions these are explicable in terms of contact inhibition; under other conditions, guidance along pre-existing pathways seems to be involved. Similar mechanisms may operate in shaping the patterns formed by growing axons. Geoffrey Burnstock (University College, London) concentrated on the interaction between axon and target at the cell level in the autonomic nervous system. He illustrated his talk with a time-lapse film in which the encounter between a growing neurite and a muscle cell could be followed. Whereas the topics addressed in the morning session were diverse, the afternoon session displayed more cohesion. The first three talks were concerned with the development of innervation in the chick limb. We had expected a confrontation between opponents of two extreme views: (1) .that motor neurons are specified centrally to connect with particular muscle groups, which they are able to seek out; (2) that the growth of motor axons to the periphery is constrained by simple mechanical factors, and that they innervate whatever muscles they happen to meet. Evidence was presented in favour of both these views. Cynthia Lance-Jones (Yale University) showed that after segments of the spinal cord had been rotated, axons from the displaced motor neurons would
under some circumstances grow out and find their usual target muscles. Vicky Stirling (N.I.M.R.) showed that after limb buds had been rotated, prior to innervation, the outgrowing motor axons under some circumstances do not now take abnormal trajectories but innervate those muscles occupying the positions of their usual targets. Julian Lewis (King's College, London) emphasized that the branching pattern of a nerve in a limb is an inherent property of the limb. The speakers seemed unrestrained by their initial prejudices, and the consensus seemed to be that the final answer will probably lie between these two extremes. There is, however, a danger in thinking in terms of neat dichotomies, and one should perhaps not be surprised should the solution turn out to be neither one nor" the other. In the final talk, John Steedman (N.I.M.R.) gave us an insight into what the new anatomical methods can tell us about the organization of fibre tracts in the brain. He described the application of the cobaltous chloride technique to the optic pathway in Xenopus. He concentrated on the normal situation, but also described the pathway taken by fibres from surgically reconstructed eyes. The rapid accumulation of information in this complex system suggests that we will not have to wait long for a Quiche Conference devoted to the subject of Eye and Brain. DAVID WlLLSHAW DENNIS SUMMERBELL
The National Institute for Medical Research, The Ridgeway, Mill Hill, London N W 7 1 A A . Further information about BRA can be obtained from Dr V. Stirling at the above address.
Advances in Neuroendocrine Physiology
J. D. B O U S F I E L D
Readinglist 1. Anon (1978) WHO Technical Report Series 622. 2. Harding, T. W. (1977) WHO Chronicle 31, 436--440. © Elsevier/North-HollandBiomedical Press 1980
An ICPS Satellite symposium dealing with Advances in Neuroendocrine Physiology will be held at Rithimna, in Crete, 7-9 July 1980. Plenary Sessions will deal with reproduction, neurotransmitters and hormone release, and the biosynthesis of brain peptides. There will also be a daily poster session. The registration fee is U.S. $65 and further information can be obtained from Dr G. Tolis, McGill University, Royal Victory Hospital, Montreal, Quebec, to whom abstracts should be submitted no later than 15 April. /
IV a~tt/mstd~om p~,e H
the problems of developing a drug distribution and dispensing network could be avoided. However, the advantages offered by existing traditional systems are not purely economic ones. Herbal medicines provide an important component of many of these ancient forms of health care. With the dawning of the age of synthetic drugs, many scientists in the world have been quick to forget that their science was founded on experiments with crude plant and animal extracts. With the realization that the vast majority of herbal medicines were effective some, however, have now turned back to plants in the hope of discovering novel bases for pharmaceutical products. The massive screening programmes for anticancer and antifertility d ~ g s serve as good examples of this current trend. Part of the apparent success of the traditional doctor may simply stem from their treatment of illness at the level of the individual, automatically taking into account the cultural and socioeconomic background to disease symptoms. In this area in particular traditional doctors, perhaps, are in advance of their Western counterparts, particularly in the case of the treatment of mental disorders. In addition to herbal remedies, meditation, induction of trances, body contact, dancing and rituals are all used in the treatment of what we would call mental illness 2. How do these remedies work? In many cases the medicinal herbs used by healers contain psychoactive components, as is the case of the Rauwolfia alkaloids, widely used in Asia and Africa. Other techniques are more difficult to evaluate, but their short-term effects are almost always striking. Acute psychoses are calmed, family disputes resolved, and hysteria disappears. The long-term effects are more difficult to assess. In Thailand, for! example, Buddhist monks treat opium addicts using herbal concoctions which act as powerful emetics. These, however, seem unlikely to be of direct physiological importance, and are instead probably more important as components of a powerful social and spiritual psychotherapy. If these methods are indeed as effective as some~ claim them to be, then the success of these ~ primitive 'health services' may provide some insights into the failings of our own.
Are axons leading us up the garden path? The second annual Quiche Conference supported by the Brain Research Association and the Company of Biologists and organized by the ebullient Vicky Sterling and colleagues, attracted 120 participants to a one-day meeting on 30 November at N.I.M.R., London, to discuss factors controlling the growth o f axons. The morning session was concerned with in vitro studies. Dennis Bray (King's College, London) presented an attractive explanation for growth cone dynamics. He suggests that the generation and movement of a growth cone across a plane surface is dictated by the compound effect of the tensions generated in each of its processes. Graham Dunn (Strangeways) discussed the patterns generated by fibroblasts. Under some experimental conditions these are explicable in terms of contact inhibition; under other conditions, guidance along pre-existing pathways seems to be involved. Similar mechanisms may operate in shaping the patterns formed by growing axons. Geoffrey Burnstock (University College, London) concentrated on the interaction between axon and target at the cell level in the autonomic nervous system. He illustrated his talk with a time-lapse film in which the encounter between a growing neurite and a muscle cell could be followed. Whereas the topics addressed in the morning session were diverse, the afternoon session displayed more cohesion. The first three talks were concerned with the development of innervation in the chick limb. We had expected a confrontation between opponents of two extreme views: (1) .that motor neurons are specified centrally to connect with particular muscle groups, which they are able to seek out; (2) that the growth of motor axons to the periphery is constrained by simple mechanical factors, and that they innervate whatever muscles they happen to meet. Evidence was presented in favour of both these views. Cynthia Lance-Jones (Yale University) showed that after segments of the spinal cord had been rotated, axons from the displaced motor neurons would
under some circumstances grow out and find their usual target muscles. Vicky Stirling (N.I.M.R.) showed that after limb buds had been rotated, prior to innervation, the outgrowing motor axons under some circumstances do not now take abnormal trajectories but innervate those muscles occupying the positions of their usual targets. Julian Lewis (King's College, London) emphasized that the branching pattern of a nerve in a limb is an inherent property of the limb. The speakers seemed unrestrained by their initial prejudices, and the consensus seemed to be that the final answer will probably lie between these two extremes. There is, however, a danger in thinking in terms of neat dichotomies, and one should perhaps not be surprised should the solution turn out to be neither one nor" the other. In the final talk, John Steedman (N.I.M.R.) gave us an insight into what the new anatomical methods can tell us about the organization of fibre tracts in the brain. He described the application of the cobaltous chloride technique to the optic pathway in Xenopus. He concentrated on the normal situation, but also described the pathway taken by fibres from surgically reconstructed eyes. The rapid accumulation of information in this complex system suggests that we will not have to wait long for a Quiche Conference devoted to the subject of Eye and Brain. DAVID WlLLSHAW DENNIS SUMMERBELL
The National Institute for Medical Research, The Ridgeway, Mill Hill, London N W 7 1 A A . Further information about BRA can be obtained from Dr V. Stirling at the above address.
Advances in Neuroendocrine Physiology
J. D. B O U S F I E L D
Readinglist 1. Anon (1978) WHO Technical Report Series 622. 2. Harding, T. W. (1977) WHO Chronicle 31, 436--440. © Elsevier/North-HollandBiomedical Press 1980
An ICPS Satellite symposium dealing with Advances in Neuroendocrine Physiology will be held at Rithimna, in Crete, 7-9 July 1980. Plenary Sessions will deal with reproduction, neurotransmitters and hormone release, and the biosynthesis of brain peptides. There will also be a daily poster session. The registration fee is U.S. $65 and further information can be obtained from Dr G. Tolis, McGill University, Royal Victory Hospital, Montreal, Quebec, to whom abstracts should be submitted no later than 15 April. /