The given code represents a section of a computational model in neuroscience aimed at simulating and visualizing certain aspects of neuronal activity and signaling. Key biological concepts encompassed in this code include: ### Neuronal Action Potentials and Membrane Voltage (V_m) - **Membrane Potential Plotting**: The code visualizes membrane voltage (V_m) dynamics for one to three neurons. Changes in V_m are crucial as they form the basis for action potentials, the primary means of neural communication. - **Spike Detection**: The code assesses membrane potentials against a threshold (`sim.activity_thr`) to identify spikes, critical for understanding neuronal firing patterns. ### Synaptic Inputs - **Input Currents (I_s)**: The code evaluates and integrates neuron inputs. The presence of negative input currents suggests inhibitory synaptic inputs, which are key in modulating neuronal excitability and network dynamics. ### Intracellular Calcium (Ca²⁺) - **Calcium Dynamics**: The intracellular calcium concentrations, potentially linked to channels modeled (e.g., I_NMDA), play an essential role in various neuronal processes, including synaptic plasticity and neurotransmitter release. ### AHP Currents (Afterhyperpolarization Currents) - **I_AHP Visualization**: The code includes afterhyperpolarization currents (I_AHP), which are critical for the repolarization phase of action potentials and help regulate firing frequency. ### Receptor-mediated Currents - **NMDA and AHP Currents**: The code accounts for currents through NMDA (N-methyl-D-aspartate) receptors (I_NMDA), which are pivotal in synaptic plasticity and learning, as well as AHP currents that help modulate firing rates. ### Spike Train, Inter-Spike Interval (ISI), and Firing Rate - **Raster Plot and ISI Calculation**: The model assesses spike timing through raster plots and calculates the inter-spike interval (ISI), reflecting neuronal rhythmic activity and firing rates in hertz (Hz), essential for understanding temporal firing patterns. ### Output Visualization - **Thorough Representation**: The code generates multiple types of output files (EPS, JPG, TIFF, PNG), ensuring versatile visualization options critical for in-depth analysis and dissemination of the neuronal data. In summary, this code fragment simulates and plots several facets of neuronal behavior, including membrane voltage changes, synaptic input processing, intracellular calcium dynamics, current flows through NMDA receptors, and afterhyperpolarization mechanisms. These features are vital for studying neuronal excitability, synaptic transmission, and plasticity within neural networks.