Signal Analysis Techniques for Multi-site Recordings of Somatosensory Evoked Potentials in Free Moving Rats

Multi-site recording techniques have been used for characterizing the activities of large populations of neurons involved in brain processing. The aim of this study is to evaluate the multi-site recording technique for brain activities and utilize signal analysis for decomposing the underlying information in a study of free moving rats. In our study, male Wistar rats were first anesthetized and then transferred to a stereotaxic apparatus for the implantation of a multi-wire electrode into the primary somatosensory cortex (SI). During the experiment, sessions of somatosensory evoked potential (SEP), induced by electrical stimulus at rat's tail base, were recorded. Using multi-site recordings, independent component analysis (ICA) was used to remove the electrical stimulus artifacts. The decomposed signals, reconstructed from selected components based on cumulative power spectra, were represented in a topographic form in order to observe the spatiotemporal distribution of the rat's brain. Our results indicated that the application of an ICA can extract the dominant components of SEPs related to drowsy and awake states of somatosensory stimuli on the subject animal. The techniques developed in this study would benefit neuroscience studies of awake, free moving rats while performing neuropsychological task.