BIO SCI N113L Lecture Notes - Lecture 1: Patch Clamp, Chronaxie, Medical Optical Imaging
Document Summary
Distinguish extracellular, intracellular, patch-clamp and optical imaging of electrical activity. Extracellular: measures voltage change along outside of cell providing a reflection of inside of cell: voltage diff b/w two recording electrodes placed outside of cell. Intracellular: measures voltage diff b/w the inside and outside of cell membrane: one into the cell, one outside. Patch clamp: measures electrical currents through single ion channels in a membrane. Optical imaging: direct visualization of voltage difference across the cell membrane: spatial and temporal resolution with voltage sensitive dye. Spontaneous activity: neuronal firing without external stimulation. Evoked activity: activity evoked by external stimulation. Identify sensory adaptation on recorded electrical activity trace. Sensory adaptation: evoked activity can often decrease as a result of prolonged stimulation. Start with larger cap, then smaller, then none. Use stimulus-duration curve to determine chronaxie time and rheobase and draw implications on neuron excitability. Rheobase: weakest stimulus that will elicit any response from the nerve: lower rheobase = greater nerve excitability.
