How Ideas About Context and Remapping Developed in Brooklyn.

In 1979, I joined Jim Ranck's group in Brooklyn and began recording hippocampal neurons. The first project was to record single neurons across three behaviors in different chambers: pellet retrieval on a radial-arm maze, bar-pressing for food reward in an operant chamber, and maternal pup-retrieval in a large home box. We found spatial firing in all three chambers, with a single-neuron's firing pattern unpredictable from one chamber to the next. We interpreted the spatial firing patterns as representing "context." Later, in the 1980s, I began collaborating with Bob Muller (and Jim Ranck). In the first of a pair of 1987 papers, we used computerized data acquisition, recorded in simple, reduced environments to demonstrate robust, stable place cell firing and the characteristic features of firing fields. In the second paper we showed that when a rat is transferred from one environment to another, the set of place cells "remaps." "Remapping" was defined later, in a pair of 1990 papers. "Context" was introduced in the early three-behavior experiment but was not discussed in the 1987 papers. What is the true relationship between the biological observation of "remapping" and the psychological concept of "context"? This difficult question is addressed here and in more detail in our recent paper.