Rall, Shepherd, Reese and Brightman (1966) identified dendrodendritic synaptic interactions between mitral and granule cells, recognized to provide for the basic function of lateral inhibition in the olfactory bulb (Rall and Shepherd, 1968). We were also the first to identify the generation by odor stimulation of activity patterns in the olfactory glomeruli (Sharp, Kauer and Shepherd, 1975), since confirmed by many different methods, and to show that these could be demonstrated by high-resolution functional MRI (Xu et al, 2003). We are continuing these studies in collaboration with Dr. Justus Verhagen at the Pierce Laboratories, and Dr. Fahmeed Hyder at the Yale Imaging Center.
Using a realistic modeling approach we have shown how backpropagating action potentials in the long lateral dendrites of mitral cells, together with granule cell actions on mitral cells within narrow columns forming glomerular units, can provide a mechanism to activate strong local inhibition between arbitrarily distant mitral cells. The simulations predict a new role for the dendrodendritic synapses in the multicolumnar organization of the granule cells. This new paradigm suggests the olfactory bulb is an excellent model system to study cortical function, the principles of which may apply to neocortical columns as well.
A key goal in neuroscience is to explain how the operations of a neuron emerge from sets of active channels with specific dendritic distributions. If general principles can be identified for these distributions, dendritic channels should reflect the computational role of a given cell type within its functional neural circuit. These modeling studies attempt to derive rules for how dendrites integrate information.
Cutting Edge Database Tools in Neuroinformatics
The SenseLab Project is a long term effort to build integrated, multidisciplinary models of neurons and neural systems, using the; olfactory pathway as a model. The project involves novel informatics approaches to constructing databases and database tools for collecting and analyzing neuroscience information, and providing for efficient interoperability with other neuroscience databases.
- the databases include neuron integrative properties (CellPropDB, NeuronDB)
- computer models of neurons (ModelDB) and microcircuits (MicrocircuitDB)
- olfactory receptors (ORDB) and odor molecules (OdorDB)
- odor-elicited patterns (OdorMapDB)
- neurological disorders (BrainPharmDB)