Cortical representations of olfactory input by trans-synaptic tracing

Research Area: A.2-Light Microscopy Year: 2011
Type of Publication: Article
Publication: Nature
  • Kazunari Myamichi
  • Fernando Amat
  • Farshid Moussavi
  • Chen Wang
  • Ian Wickersham
  • Nicholas R. Wall
  • Hiroki Taniguchi
  • Bosiljka Tasic
  • Z. Josh Huang
  • Zhigang He
  • Edward M. Callaway
  • Mark Horowitz
  • Liqun Luo
In the mouse, each class of olfactory receptor neurons expressing a given odorant receptor has convergent axonal projections to two specific glomeruli in the olfactory bulb, thereby creating an odour map. However, it is unclear how this map is represented in the olfactory cortex. Here we combine rabies-virus-dependent retrograde mono-trans-synaptic labelling with genetics to control the location, number and type of ‘starter’ cortical neurons, from which we trace their presynaptic neurons. We find that individual cortical neurons receive input from multiple mitral cells representing broadly distributed glomeruli. Different cortical areas represent the olfactory bulb input differently. For example, the cortical amygdala preferentially receives dorsal olfactory bulb input, whereas the piriform cortex samples the whole olfactory bulb without obvious bias. These differences probably reflect different functions of these cortical areas in mediating innate odour preference or associative memory. The trans-synaptic labelling method described here should be widely applicable to mapping connections throughout the mouse nervous system.