photo of Mimi Halpern

Mimi Halpern, PhD

Department of Cell Biology

Biology of Nasal Chemical Senses:

Most terrestrial vertebrates possess several nasal chemoreceptive systems including the olfactory and vomeronasal systems. The major focus of interest in this laboratory is to understand the structure and functional significance of the vomeronasal (VN) system and to contrast it to the main olfactory system (MOS). Among our early contributions was the demonstration of the dynamic nature of the snake's VN epithelium and its capacity for regeneration following degeneration.

Our behavioral studies have demonstrated the critical importance of the garter snake VN system in prey attack, prey extract attack, prey extract trailing, aggregation and male courtship of attractive females. We have also demonstrated that stimulation of the VN system is intrinsically rewarding to snakes. At this time we are investigating the role of the various brain structures that form part of the circuitry for tongue flicking on tongue response to chemical stimuli.

One of the central concerns in chemosensory science is understanding the mechanism of sensory transduction. The bias, at present, is to look for receptor proteins on membranes of receptor cells. We have isolated and characterized a number of proteins from prey (earthworm) products that are vomeronasally mediated chemoattractants for snakes. Among these proteins is a 20 kDa glycoprotein that binds specifically to VN receptor membranes and induces changes in second messenger systems in VN receptor cells.The major second messenger system used by the vomeronasal receptor cells of snakes is inositol 1,4,5-trisphosphate. Currently we are investigating the role of calcium release in the signal transduction process.

Electrophysiological studies have, using single unit extracellular recording from mitral cells in the accessory olfactory bulb or main olfactory bulb, demonstrated that prey extracts delivered to the VN epithelium as liquids activate the VN system, but similar extracts delivered as air streams do not. Conversely, prey extracts delivered as air streams to the MO epithelium activate the MOS, but similar extracts delivered as liquids do not.

We have studied the development and organization of the VNS in the South American grey short-tailed opossum, Monodelphis domestica. The accessory olfactory bulb is heterogeneous with respect to a number of markers and it appears that the receptor cells in the VN epithelium are similarly heterogeneous. We have found that there are at least two parallel VN pathways from periphery to the brain, and that these parallel pathways extend more centrally into the amygdala. We are now studying the functional correlates of these parallel pathways.

  • Ping Chen, Technical Specialist, Ex. 1260
  • Mimi Halpern, Professor of Cell Biology, Ex. 2416
  • Changping Jia, Research Assistant Professor Cell Biology, Ex. 1022
  • Wei Quan, Institutional Support Specialist, Ex. 2249
  • Dalton Wang, Associate Professor of Biochemistry, Ex. 1260
  • Ido Zuri, Postdoctoral Trainee, Ex. 1022
  • Yingjia Liu, Research Laboratory Worker, Ex. 1022

List of Publications (Pub Med)

Department Links

Cell Biology