Basic NeuroscienceSensory and cognitive neurophysiology in rats. Part 2: Validation and demonstration

- Multi-unit activity (MUA) can be measured using micro-ECoG.
- Pre-stimulus oscillatory phase modulates tactile evoked responses in the MUA.
- Sensory expectation modulates tactile evoked responses in the MUA.

BackgroundWe have developed a novel setup for rats that allows for controlled sensory input to an animal engaged in a task while recording both electrophysiological signals and behavioral output.New methodOur setup is described in a companion paper.ResultsWe validate our setup by replicating (1) the functionally nonspecific spread of neural activity following tactile stimulation, and (2) the effects of anesthesia on the tactile evoked responses.We also demonstrate for the first time that the ECoG can be used to record evoked responses in a signal that reflects neural output (spiking activity), and illustrate the usefulness of our setup by demonstrating that these evoked responses are modulated by both the phase of pre-stimulus oscillations and by expectation.Comparison with existing methodsCompared with high-density wire recordings, micro-ECoG offers a much more stable signal without readjustments, and a much better scalability. Compared with extracranial and regular ECoG recordings, micro-ECoG allows us to measure signals that reflect both neural input and neural output.ConclusionsFor sensory and cognitive research, our setup provides a unique combination of possibilities that cannot be achieved in other setups for rodents.