## Biological Basis of the Code The provided MATLAB code is part of a computational model of thalamocortical neural dynamics, specifically focusing on the behavior of the EEG during Non-Rapid Eye Movement (NREM) sleep and its response to auditory stimulation. The biological aspects modeled in this code involve neuron dynamics within the thalamocortical system, which include: ### Thalamocortical Network Dynamics 1. **Thalamocortical Neurons (Vt):** The variable `Vt` represents the membrane potential of thalamocortical neurons. These neurons form part of the thalamocortical network, which plays a critical role in the generation of sleep spindles and slow oscillations during NREM sleep. 2. **Pyramidal Neurons (Vp):** The variable `Vp` denotes the membrane potential of pyramidal neurons in the cortex. Pyramidal neurons are integral to cortical processing and are involved in generating slow oscillations (SOs), characteristic waveforms of NREM sleep. 3. **h-current (ah):** The variable `ah` refers to the activation of the hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, also known as the h-current. The product `ah.*51` is a scaled representation of the conductance `g_h`, given in `μS/cm²`. This current is crucial for regulating rhythmic activity in neurons, impacting the generation and modulation of thalamocortical oscillations during sleep. ### Endogenous and Stimulated Conditions - **Endogenous SOs:** The model differentiates between spontaneous (endogenous) slow oscillations (SOs) during natural NREM sleep and those influenced by external stimuli. The code loads and visualizes endogenous SOs through the variables `Vp_endo`, `Vt_endo`, and `ah_endo`. - **Closed-loop Stimulation:** The model also explores effects of auditory stimulation on the thalamocortical network, examining how these stimuli can affect SO dynamics, which is visualized using `Vp_stim`, `Vt_stim`, and `ah_stim`. ### Plot Characteristics - **Temporal Dynamics:** The `timeaxis` and changes in membrane potentials `Vp` and `Vt` over time illustrate dynamic neuronal behaviors, focusing on a 5-second temporal window, important for understanding the oscillatory cycles of the thalamocortical system. - **Voltage and Conductance:** Particular attention is given to membrane potentials, ranging from negative voltages (indicating hyperpolarization) to less negative values (suggesting depolarization), key properties of neuronal excitability and oscillatory behavior. Additionally, `g_h`, the conductance value derived from the h-current, underscores its role in shaping the oscillatory patterns during different conditions (endogenous vs. stimulated). Overall, this code models essential components of thalamocortical dynamics with a focus on their biological underpinnings, helping to understand the processes involved in EEG patterns during NREM sleep and how they might be altered by external auditory stimuli.