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Abstract

<p>Cellular processes in neural tissues generate movement of electrical charges. Multiple techniques for measuring this electrical activity allow for characterization of cellular processes at different scales of the brain tissue. In particular, electrodes inserted deep into the brain record electric fields referred to as the local field potential (LFP? Buzsáki, et al., 2012). It is believed that LFP characterize inputs to the network of neurons surrounding the electrode. However, the contributions of other sources to LFP are actively discussed. In cortical networks, LFPs are strongly correlated with another measure of the electrical activity spike recordings from individual neurons. Thus, the neurons contribute to LFP, and it is possible to figure out their individual contributions through the use of a linear filtering mechanism (Rasch, et al., 2009). First, we successfully repeated this analysis in the rat Prefrontal Cortex (PFC). However, this has proven not to be possible in other areas, such as the midbrain. In particular, neurons in the Ventral Tegmental Area (VTA) are not as well spatially aligned as cortical neurons and fire mostly asynchronously, which leads us to believe that their electric fields may cancel instead of summing in the LFP readings. Because of this, the local LFP signal may be dominated by volume conducted signals from other brain regions. A combination of current source density (CSD) analysis and Independent Component Analysis (ICA) has been used in previous work by ?eski et al. (2009) to solve this problem. We used this approach on the VTA single unit and LFP signals This method allowed us to find the specific sources of LFP signals in the VTA and the contribution of particular neurons to the cumulative LFP.</p>