1. Howard Hughes Medical Institute, Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, USA
2. Gastrointestinal Unit (Medical Services), Massachusetts General Hospital, Department of Medicine, Harvard Medical School, Boston, Massachusetts 02114, USA
3. These authors contributed equally to this work

Correspondence to: Linda B. Buck¹ Correspondence and requests for material should be addressed to L.B.B. (e-mail: Email: lbuck@hms.harvard.edu).

Abstract

The olfactory system translates myriad chemical structures into diverse odour perceptions. To gain insight into how this is accomplished, we prepared mice that coexpressed a transneuronal tracer with only one of about 1,000 different odorant receptors. The tracer travelled from nasal neurons expressing that receptor to the olfactory bulb and then to the olfactory cortex, allowing visualization of cortical neurons that receive input from a particular odorant receptor. These studies revealed a stereotyped sensory map in the olfactory cortex in which signals from a particular receptor are targeted to specific clusters of neurons. Inputs from different receptors overlap spatially and could be combined in single neurons, potentially allowing for an integration of the components of an odorant's combinatorial receptor code. Signals from the same receptor are targeted to multiple olfactory cortical areas, permitting the parallel, and perhaps differential, processing of inputs from a single receptor before delivery to the neocortex and limbic system.