BME 4900 Final Report - Biomedical Engineering - University of ...

BME 4900 FINAL REPORT 11Team 8desired input-output relationships. Next, this signal passes to the neural cell soma,which prevents current backflow and primes the axon for excitation. Finally, this signalreaches the post-synaptic axon, which restarts the entire cycle by generating signatureaction potential firing patterns dependent on the type of neural population.2.2.2 Generalized Neuron CircuitDendriteThe dendrite component of the neuron the region that, in most cases, receives thesignal from the synapse of the previous neuron or from some sort of neural receptor. Thesignal is the propagated down the dendrite to the soma. The dendrite is unmyelinated,and as a result, demonstrates significant current leakage. The amount lost is related tothe size of the dendrite, most notably the dendrite diameter and length.The dendrite may be modeled compartmentally using an iterative RC circuit.Each compartment contains three components representing the axial resistance (R a),membrane resistances (R m), and the membrane capacitance (C m) (see Fig. 7).Figure 7. The two possible compartment circuits for a dendrite. The left schematic shows thestandard dendrite compartment, while the right schematic shows the special case of the firstcompartment, which contains one less axial resistance representation.These compartments may be strung in series or in parallel in order to account fordendrite length and any branching that occurs (see Fig. 8). Branching allows for a