Codes and circuits.

Marshall Nirenberg will always be remembered for deciphering the genetic code by which DNA and RNA sequences specify the amino acid sequence in proteins. His switch to neurobiology in the 1960s was driven, in part, by an interest in the possibility of a neural code specifying the development and functioning of the neural circuits that underlie brain function. Neural cell adhesion or recognition molecules would probably be involved in such circuit formation, and this review briefly examines one set of such molecules. The specific binding between presynaptic neurexins and postsynaptic neuroligins could constitute one aspect of the code underlying the formation of specific synaptic circuits.