Senior Research Project Blog - Week 1

I spent this week focused on establishing the foundation for my project on how anesthetics and pharmacological agents influence neural signal propagation. The first step recommended by my mentors was to conduct a systematic review summarizing current research on anesthetic mechanisms, synaptic transmission, and neural conduction. The purpose of this document is to organize the existing research, identify key findings in the field, and determine where important gaps remain.

I reviewed nearly 50 major papers examining how general anesthetics affect neuronal signaling. Many studies show that anesthetics alter neural activity primarily through ion channels embedded in the cell membrane. These compounds often enhance inhibitory signaling while suppressing excitatory transmission, shifting the balance of neural activity toward inhibition. Other studies examine how anesthetics influence neural networks rather than individual neurons alone. Research on propofol-induced unconsciousness suggests that neuronal communication across brain regions becomes disrupted as anesthetic concentration increases. Functional networks fragment, reducing long-range connectivity and contributing to the transition from conscious to unconscious brain states.

The literature also stresses the importance of membrane biophysics and ion channel function. Voltage-gated sodium and potassium channels control the propagation of action potentials along axons, starting at the axon hillock, while calcium channels in the axon terminal regulate neurotransmitter release at synapses. Some anesthetics reduce calcium influx into presynaptic terminals, which weakens synaptic transmission. Because ion channel behavior depends strongly on membrane properties and temperature, these mechanisms connect directly to the thermodynamics component of the broader research project.

In addition to reviewing the literature, I began outlining experimental directions. The first priority will be establishing a stable experimental environment where neural tissue remains viable in physiological saline such as Ringer’s solution. Once neural activity can be reliably recorded, experiments can begin examining how drugs and other factors influence signal propagation. I have developed a rough draft of the methodology, from Phase 0 to 7, those being Tissue Viability and Baseline Stability, Basic Propagation Characterization, Local Anesthetic Validation, General Anesthetics and Propagation, Ligand-Gated Ion Channel Modulation, Temperature and Thermodynamic Coupling During Drug Application, Frequency-Dependent Propagation and Energy Demand, and finally, Infrared Stimulation Versus Electrical Stimulation.

Next week, when Dr. Claus Peter Richter returns, Dr. Joaquin Cury and I will begin initial validation experiments. We will first measure the compound action potential in an isolated nerve preparation to confirm that the electrodes are properly detecting signal propagation. Lidocaine will then be applied to suppress sodium channel activity and verify that the recorded signals respond appropriately to known anesthetic effects. After validating the recording system, we will test whether the Ringer’s solution we prepare is able to sustain the nerve’s viability for extended periods. Establishing these baseline conditions is essential before more complex experiments examining drug effects and membrane thermodynamics can begin.