Physio 07: Neurotransmitters & Neuromodulators

Not all messages in the nervous system say the same thing, even when they travel along the same path. What determines whether a signal excites, inhibits, sharpens, softens, or reshapes behaviour is not electricity alone—but chemistry.In this episode, Medlock Holmes turns his attention to neurotransmitters and neuromodulators: the chemical vocabulary of the nervous system. We explore how classical neurotransmitters produce fast, point-to-point communication, while neuromodulators alter the context in which signals are received—changing gain, probability, timing, and plasticity.Rather than memorising lists of transmitters, this episode focuses on functional logic: why some signals must be rapid and precise, why others must be diffuse and slow, and how the same chemical can have profoundly different effects depending on receptor type and cellular state.Here, physiology teaches us that communication is never just about delivery.It is about interpretation.Key Takeaways* Neurotransmitters mediate fast, localised synaptic communication* Neuromodulators shape network behaviour over longer time scales* Receptor type determines response, not the transmitter alone* One chemical signal can excite, inhibit, or modulate depending on context* Chemical signalling enables plasticity, learning, and adaptability This is a public episode. If you'd like to discuss this with other subscribers or get access to bonus episodes, visit drmanaankarray.substack.com/subscribe