Cell physiologist and Nobel laureate Erwin Neher plans to retire three years from now, when he is 68. In the meantime, he is 'trying to understand' - a scientist's catchphrase for discover - the brain mechanism that causes Alzheimer's, Parkinson's and other neurodegenerative diseases. That might just be another ground-shaking contribution to mankind from Professor Neher, whose passion for neuroscience dates at least to his secondary school days - if not to his experiments with snails as a child in his family home in Bavaria, Germany. But don't hold your breath, Professor Neher says. The brain-disease breakthrough might not happen any time soon. The quest for Professor Neher, who shared the 1991 Nobel Prize with fellow German Bert Sakmann, is to try to understand how people contract autoimmune diseases that damage the most complex organ in the body. 'My aim is not to solve the puzzle of Alzheimer's or Parkinson's,' he says. 'I want to understand a few details which might contribute to the knowledge in this field. I have no hopes that tomorrow I will find something which will cure Alzheimer's. It would be too ambitious.' The low-profile, soft-spoken scientist gave an interview to the Sunday Morning Post ahead of his Sun Hung Kai Properties Nobel Laureates Distinguished Lecture last Tuesday at Chinese University. It was the first visit to Hong Kong for Professor Neher, who serves as director of the membrane biophysics department at the Max Planck Institute for Biophysical Chemistry in Goettingen, Germany. He also fitted in a trip to the mainland, where he attended a conference and met fellow scientists. Professors Neher and Sakmann were co-awarded the Nobel Prize for physiology or medicine for their revolutionary research conducted between 1973 and 1985 to discover the function of ion channels. These consist of single molecules or complexes of molecules that have the ability to allow the passage of charged atoms, called ions. Professor Neher was 29 when they began their research, Professor Sakmann two years older. The pair developed a technique using a thin glass micropipette - a thousandth of a millimetre in diameter - as a recording electrode for ion channel activity in cells. 'This new knowledge and this new analytical tool has during the past 10 years revolutionised modern biology, facilitated research and contributed to the understanding of the cellular mechanisms underlying several diseases, including diabetes and cystic fibrosis,' the Nobel Prize committee said at the time of the award in 1991. 'We succeeded because we understood a little better the underlying problems,' Professor Neher said. 'We were very lucky because it turned out that such ion channels are operating in many cells - in our eyes, our ears, the whole body - doing many things.' The two professors continued their collaboration until 1989 when Professor Sakmann moved to Heidelberg. He retired last year aged 65. Professor Neher's continuing passion is to explain the role of neurotransmitters in the development of debilitating and incurable brain diseases. 'When one nerve cell 'speaks' to another one in a synapse - when a signal is transmitted from one to the other - the sending cell releases the neurotransmitter substance, which then causes a change in the receiving cell,' Professor Neher said. 'And we [would] like to understand the mechanism [that governs] how these neurotransmitters are being released.' In the brain, the connection strength among cells is 'plastic - always changing, depending on the flow of information', he said. If you use a synapse over and over, then it leaves a long-lasting mark on it for days, weeks or months. These are long-term plastic changes. 'People think our memory is represented by these long-term changes,' Professor Neher said. 'Such changes also happen from second to second. Neurons in our brain are constantly rewired, and most neuroscientists are convinced it is this plasticity which makes the brain so special. It is one of the big ways in which a computer is different from the brain.' The immediate cause of brain diseases is loss of neurons. Scientists believe that when neurons die they are often lost forever. 'If this continues to a certain degree, depending on which area of the brain, then you will have Alzheimer's or Parkinson's,' he said. Professor Neher said he had always been on the same path of discovery: from calcium channels - those channels that lead calcium to enter the cells - and the many other cell functions connected to this process. He said scientists should never stop asking the big questions. 'There is no plan for becoming a Nobel laureate. [The] chances are best if a scientist just tries to follow his or her ideas,' he said. 'So follow your intuitions and - as a little aside - your interest [must be] really an important problem. 'You shouldn't just solve a problem which is [out on the fringes]. The best strategy is to identify an important problem - but it must be a problem which completely captivates your ideas and your thoughts.'