Depth distribution of frontal cortical field potential to acoustic stimulation in unrestrained non-anaesthetized rats

Intracortical depth profiles of acoustically evoked potentials (AEP) through the frontal cortex were studied with moveable electrodes in 5 freely behaving rats to identify the generators of the AEP components with current source-density analysis in pharmacologically uninfluenced relaxed wakefulness. The main negative AEP components (N21 and N38) which change their polarity across the cortical depth are generated by extracellular current sinks within the V cortical lamina. Since both components were polarity reversed in different cortical depths and have their current sources in different laminae, the participation of different generation modi are assumed for both AEP components.