| This is an integrative study that combines information obtained by the use of selective probes and direct chemical profiling of individual neurons for the investigation of physiological and behavioral aspects of cell signaling mediated by neuropeptide transmitters in the brain of Aplysia californica . This combination of techniques provides complementary qualitative information on the peptide structural identity, localization and action within a particular neuronal circuit. The study tests the hypothesis that specific neuropeptide transmitters expressed in a relatively restricted number of neurons in the central nervous system might indicate on functionally-related circuit of neurons. Alternatively, the analysis of known neuronal populations having similar functional roles in behavior is used to investigate a set of known and novel putative neuropeptide transmitters and/or modulators acting within the circuit. An added advantage of mass spectrometry to derive the structural information by sequential fragmentation of the peptide molecular ion is used in this work for the investigation of proteolytic processing of neuropeptide prohormones and posttranslational modifications of mature peptides in individual identified neurons. Many of the aspects of neuronal signaling would better be understood, if studied in vivo. The structural and chemical complexity of the brain, however, precludes from the detailed investigation of individual factors and mechanisms resulting in a cellular and behavior response. To circumvent the limitations of the in vivo brain research, this work applies a full suite of techniques to develop an approach for investigation of the parameters essential for forming functional neuronal networks---the morphology, biochemistry and excitability---of neurons under defined cell culture conditions. Using the microfluidics and the self-assembled monolayer technologies this work investigates how the physicochemical properties of the support layer influence the electrical activity of the cultured neurons and how they can be used for predictably altering/engineering the neuronal properties by modulation of the chemical, physical, and topographical features of culture substrates. |
