At that time 'biological cybernetics' was a field that fascinated many students of biology and physics. Werner Reichardt's and Bernhard Hassenstein's quantitative behavioural analysis of a beetle's optomotor response promised to make brain functions understandable in terms of information theory. Otto Creutzfeldt in the Kraepelin Institute in Munich accepted me as a doctoral student to work on the electrophysiological basis of pattern recognition. Although small by today's standards, the Kraepelin Institute encompassed almost all aspects of neurobiology at the time, ranging from voltage clamp current recordings from snail neurones in Dieter Lux's department to quantitative analysis of monkey behaviour in Detlev Ploog's department. In Otto Creutzfeldt's department, great enthusiasm and optimism prevailed in trying to understand and build models of pattern recognition by the visual system, and there was close collaboration with electrical engineers and computer scientists from the Munich Technical University. After three years of experimental work on the neurophysiological basis of light adaptation in the cat's visual system I realized that the central nervous system (CNS) was too difficult to comprehend without understanding the synaptic connections more clearly. I went to a course on basic mechanisms of vision in a summer school and I attended a lecture given by Bernard Katz on nerve, muscle and synapse, which convinced me that cellular physiology would be very helpful in trying to understand the functions of the central nervous system. To gain experience in voltage clamping I joined Dieter Lux's laboratory and learned from Erwin Neher how to voltage clamp synaptic currents in snail neurones before moving to Bernard Katz's department at University College, London.
There I worked with Bill Betz for one year, learning the basics of synaptic transmission and taking apart the neuromuscular synapse into its pre- and postsynaptic elements. During the following two years I learned, with Dale Purves, that the neuromuscular synapse is also a good model for studying long-term changes in chemical and electrical excitability. During this time Bernard Katz and Ricardo Miledi discovered 'membrane noise' and 'elementary events', and Linc Potter and Ricardo Miledi in the same department made the first attempts to count and isolate acetylcholine receptors. I was very lucky to be at University College at this particular time, when both the electrophysiology and the biochemistry of synaptic transmission became molecular. It seemed that a molecular understanding of the end-plate currents was within reach, and it became clear to me that I wanted to work on the molecular aspects of synaptic transmission, and on the development of synapses, which is what I have been doing since. The major experimental challenges were the direct recording of the elementary events that had been postulated from Katz and Miledi's experiments, the biochemical and structural characterisation of the acetylcholine receptor molecule, and the relation between structure and function of ion channels and receptors.