The provided code is part of a computational model aimed at simulating the olfactory bulb (OB) neural network, specifically focusing on the interactions between mitral cells (MCs) and granule cells (GCs). Here's a breakdown of the biological basis of the model: ## Biological Basis ### Olfactory Bulb (OB) Network The olfactory bulb is the first site of neural processing in the olfactory system. It consists of various cell types, with mitral cells and granule cells being prominent. Mitral cells receive input from the olfactory sensory neurons and are involved in transmitting sensory information to higher brain areas. Granule cells modulate the activity of mitral cells through inhibitory synapses, influencing patterns of olfactory processing. ### Mitral Cells (MCs) Mitral cells are the primary output neurons of the olfactory bulb and project their axons to various parts of the olfactory cortex. They play a crucial role in encoding and processing olfactory information. The code focuses on: - **Currents in MCs:** The model calculates external current (`Iext`) and graded inhibitory currents (`Igradistmit`) to simulate realistic neuronal input to the mitral cells. - **Membrane Potentials (Voltage):** The code records the membrane potentials (`V`) of each mitral cell across simulation time, essential for understanding the action potential generation and neuronal firing patterns. ### Granule Cells (GCs) Granule cells are interneurons that provide inhibitory feedback to mitral cells. Although they are not directly analyzed in the provided portion of the code, they are implied in the calculation of Local Field Potentials (LFPs), which involve GCs: - **LFP Simulation:** The model simulates local field potentials associated with MCs, which are influenced by the inhibitory feedback from granule cells. While MC local field potentials (`GradistMitGlobal` and `VG`) are explicitly modeled, the GCs' contribution is scoped in the broader model. ### Local Field Potentials (LFPs) LFPs represent the summed electric currents from multiple neuronal activities in a region of tissue and provide insights into the synaptic activity and communication between neurons. In this code: - **MC LFPs:** Simulated using current-based (`GradistMitGlobal`) and voltage-based (`VG`) metrics from mitral cells. These help capture the network oscillatory dynamics and reflect how MCs and their synaptic inputs, primarily influenced by grand granule cells, interact in the OB. ### Parameter Sweeping The methodology iteratively tests different parameter values (defined by structures `P1` and `P2`) to explore how variations in parameters like synaptic strengths, input currents, or neuronal excitability affect the olfactory bulb’s computational properties. This form of parametric analysis helps elucidate how biological variability and perturbations in the system could impact olfactory processing. In summary, this code models the dynamics of mitral cells within the olfactory bulb network, focusing on understanding how these neurons integrate excitatory and inhibitory inputs to generate complex patterns of neural activity. This helps in dissecting the fundamental biological processes underlying olfactory perception and neural computations in the OB circuit.