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Dr Peter Brennan

Pheromones and olfactory Learning

Humans take their sense of smell for granted, but it is the major sensory system for most animals. There has recently been a molecular genetics-led revolution in our understanding of this previously neglected sense. Now a major focus of research effort is devoted to understanding the processing of odour information and the role of learning in odour perception. In particular, recent findings have shed light on the diversity of specialised chemosensory subsystems that mediate innate behavioural and physiological responses to pheromones.

My group's research is focused on investigating the neural basis of learning in the olfactory bulb, at the first stage of olfactory processing of odour information. We are particularly interested in the neural basis of mate recognition in mice, which is one of the few mammalian examples in which learning at the behavioural level can be explained by changes at synapses between identified neurons in the brain. Previous work has shown that memory formation depends on the association of chemosensory input to the vomeronasal system and the high levels of noradrenaline that occur in the olfactory bulb at mating. These are associated with dramatic changes in the functioning of the accessory olfactory neural network that selectively gates transmission of the learned information. Current work is aimed at understanding the receptor mechanisms by which noradrenaline imprints the neural system and how changes in feedback inhibition shape synchronized oscillatory activity of the accessory olfactory bulb mitral cells to gate sensory transmission to central brain areas, such as the medial amygdala and hypothalamus.

Research keywords

  • Vomeronasal
  • pheromones
  • olfactory bulb
  • amygdala
  • major histocompatibility complex

Processes and functions relevant to this work

  • Memory
  • individual recognition
  • reproductive behaviour


  • Dr Ashok Hedge - Wake Forest University - USA
  • Prof Tom Boehm - Max-Planck Institute of Immunobiology - Freiburg - Germany
  • Dr Matthieu Keller - CNRS - Dijon - France