Abstract
In order to facilitate the understanding of complex neuroscientific questions in vivo, it is often necessary to carry out extracellular recordings via chronically implanted electrode arrays. Spike sorting and clustering utilizes these recordings by grouping neuronal waveforms stemming from the same cell into individual clusters in order to examine activity of single-units over time. Only when spike sorting and clustering is of sufficient quality can it be reliably applied to answer scientific questions about cellular communication in relation to various behavioral states or processes. This is applicable to the study of sensory system input, cognition, and behavioral output. Strikingly, even the activity of primary sensory cortices, once believed to almost exclusively process feedforward information of a single sensory modality, are dramatically changed by ongoing behavior. As a result, one such important question arising is: how does locomotion affect neuronal firing rates in visual cortex? Despite the large amount of evidence for locomotion increasing firing rates in V1 in mice, such experiments have utilized head-fixed animals constrained to a ball or treadmill. In order to answer this question in freely behaving \r animals, we developed and enacted novel methods of quality control by identifying bimodal waveform properties at the hourly scale. We then compared epochs of active and quiet wake in freely behaving rats, where quiet wake was defined as periods of both stationarity and grooming. We further asked if this changed during brief periods of light and dark. Our results demonstrated lack of change in firing between active and quiet wake. We further showed that locomotion does not differentially impact neuronal firing in V1 in light versus dark . This suggests that active and quiet wake behavioral states do not moderate activity in visual cortex of freely behaving animals.