# Biological Basis of the Computational Model The provided code models certain interactions within the olfactory bulb of the mammalian brain, focusing specifically on the connections between distinct neuronal types: **mitral/tufted cells**, **Blanes cells**, and **granule cells**. Here's how these components relate to the biological system: ## Neuronal Circuitry ### 1. Mitral/Tufted Cells Mitral and tufted cells are the principal output neurons of the olfactory bulb. These cells receive direct sensory input from the olfactory nerve and send outputs to the olfactory cortex. In the code, `mt2blanes` represents the connections from mitral/tufted cells to Blanes cells, highlighting their role in modulating olfactory signals. ### 2. Blanes Cells Blanes cells are a specific type of inhibitory interneuron found in the olfactory bulb. These cells are responsible for modulating the activity of other neurons within the olfactory bulb through inhibitory neurotransmission. In the provided code, Blanes cells receive inputs from mitral/tufted cells and project to granule cells. This interaction is represented by the construction of `mt2blanes` and `blanes2granule` classes, where the `mk_bl2g_connections` function pertains specifically to Blanes to granule cell connections. ### 3. Granule Cells Granule cells are interneurons within the olfactory bulb engaged in reciprocal dendrodendritic synapses with mitral and tufted cells. The main function of granule cells is the modulation of output from the olfactory bulb through inhibition. The `blanes2granule` class in the code models the inhibitory synaptic connections from Blanes cells to granule cells. ## Synaptic Transmission ### Excitatory Synapses The code uses the `h.Exp2Syn` mechanism to model synaptic connections, specifically for excitatory synapses where the reversal potential (`e`) is set to 0 mV, which is typical of excitatory post-synaptic potentials involving sodium ion influxes. ### Inhibitory Synapses The inhibitory nature of the Blanes to granule cell connection is evident from the reversal potential (`e`) being set to -80 mV in `blanes2granule`, consistent with GABAergic (inhibitory) synapses that involve chloride ion conductance. ## Model Parameters and Connections - **`tau1` and `tau2`**: These parameters are time constants for the synaptic conductance rise and decay, respectively, indicative of the dynamics of neurotransmitter binding and release from the synaptic cleft. - **`glom2blanes` and `bc2gc_inh_gmax`**: Parameters define the connectivity and inhibitory strength between cell types, with `glom2blanes` mapping glomeruli to Blanes cells and `bc2gc_inh_gmax` setting maximum conductance values for inhibitory connections. ## Conclusion The code provides a modular and structured representation of a segment of the olfactory microcircuitry, emphasizing the interactions between principal neurons and inhibitory interneurons. By capturing the connections and synaptic dynamics between mitral/tufted cells, Blanes cells, and granule cells, this model aims to mimic the complex inhibitory and excitatory interactions that occur within the olfactory bulb to regulate sensory signal processing and output to higher brain regions.