Daniel Bowman

Efforts Towards a New, Bimetallic Cyclophane for Supramolecular Self-Assembly

Examples of supramolecular self-assembly are abundant in nature. Two examples, which are well known for their biological importance but not as quintessential examples of self-assembly, are cell membranes and DNA. Other self-assembly molecules containing metal atoms have presented examples in which rings and cages of varying sizes and shapes are constructed. In this project, a unique, metal-containing building block is being prepared for testing in the construction of subsequent self-assemblies.

Slowly-developing Alterations in Nucleus Accumbens Neuronal Activity

The nucleus accumbens (NAc) is thought play a prominent role in motivational processes underlying goal-directed behavior. Consistent with this notion, chronic electrophysiological studies monitoring the activity of individual NAc neurons during operant behavior have revealed phasic (rapid) alterations in firing rate tightly correlated with discrete appetitive or consummatory responses in operant behavioral paradigms. However, whether NAc neurons exhibit slowly-developing alterations in firing rate potentially related to motivational state has not been extensively examined. Here we report data from a set of 50 NAc neurons recorded during performance of an operant task involving sucrose reward. Consistent with a recent report (Synapse, 60(6): 420-8), many cells exhibited tonic changes in firing rate that developed slowly over minutes to tens-of-minutes during the behavioral session, and these patterns could often be explained by parallel changes in behavioral response density.
However, a small subset of cells exhibited tonic alterations that were independent of observable behavior. These patterns of activity provide a possible substrate for the neural representation of state variables related to motivational state.