Compact High Performance Liquid Chromatrography (HPLC) System

The purpose of this order is to procure linear multiple-electrode arrays to be used in electrophysiological experiments to investigate the neural response properties in multiple brain areas during the process of curvature. The brain processes visual stimuli along different feature dimensions, including edge orientation, visual motion, and color. To expedite visual processing, cells that process a common visual dimension are often anatomically grouped in cortical columns, patches, and/or areas. We tested the hypothesis that 1) image curvature is one of these fundamental visual dimensions and, as such, 2) curvature-selective cells are grouped together in discrete cortical areas. Using neuroimaging techniques, we confirmed this hypothesis, and localized the curvature-processing sites in extrastriate visual cortex. These sites lay along a common cortical strip, spanning lower- to higher-level processing stages. Furthermore, the curvature-processing sites are adjacent to the well-known face-processing cortical areas, suggesting a possible functional link between them. The study is currently under revision for publication (DIRP Publication and Abstract Clearance Request #113942). It is critical to record neural activities in the curvature processing areas in the brain in order to understand the computation mechanisms underlying curvature processing. The proposed purchase will be essential to conduct successfully the single recording experiment that will lead to comprehensive understanding of curved features processing, and provide insight how features are integrated into objects in the brain. The second goal that this purchase will be needed to achieve is to clarify the anatomical connection between curvature processing areas, which is the step-stone to comprehend the neural computation underlying the curvature-processing network. Electrical micro-stimulation will be utilized to answer the question. When one cortical area is stimulated with a low current delivered through an electrode implanted in the brain, other cortical areas anatomically connected to the stimulated area will be activated. This simultaneous activity, which can be detected using fMRI, will reveal the connections between a stimulated area and patches of anatomically connected areas. Connections between curvature areas that will be uncovered by simulating each of the curvature patches will provide critical information on how computation of curved features flows within the network. Linear multiple-electrode arrays are an idea tool to achieve the two goals. A linear electrode array composes of a single electrode probe with multiple contacts, each of which works as an independent recording electrode. Within single penetration, a linear electrode array provides the ability to: 1) record multiple single unit activities and local field potential; 2) record neural activities from different cortical layers; 3) record neural activities from different cortical areas (using long electrodes); 4) stimulate different cortical layers; 5) simultaneously recording and micro-stimulation, which significantly increase efficiency while reducing animals' stress as compared to using traditional single electrode.