P300- like event related potential amplitude in rats is a correlate of conditioned reinforcement

We have developed a methodology for recording a robust P300 event related potential (ERP) in rats. In these experiments a contingency shaped model of the human “oddball’ paradigm was employed in which rats were shaped to press a lever for food reinforcement signaled by the click of the pellet dispenser. A target tone cued the insertion of the lever that retracted after 1­sec or immediately following a single reinforced response, while a non­target tone was randomly presented. Brain activity was recorded through stainless steel electrodes implanted 1mm below the skull. Here, we compared the amplitude of the P300 response to the click of the pellet dispenser to the amplitude of the P300 response to the target and non­target tones. We found that the amplitude to food click was significantly greater that the amplitude to the target tone that cued lever insertion. Since the food click is more proximal to the primary reinforcer than the lever tone, it is a stronger conditioned reinforcer than the lever tone that sets the occasion for the food click. Accordingly we suggest that the P300 in rats is a correlate of conditioned reinforcement

Duality and Central Charges in Supersymmetric Quantum Mechanics

We identify a class of point-particle models that exhibit a target-space duality. This duality arises from a construction based on supersymmetric quantum mechanics with a non-vanishing central charge. Motivated by analogies to string theory, we are led to speculate regarding mechanisms for restricting the background geometry.Comment: 10 pages, 1 figure, late

A "Periodic Table" for Supersymmetric M-Theory Compactifications

We develop a systematic method for classifying supersymmetric orbifold compactifications of M-theory. By restricting our attention to abelian orbifolds with low order, in the special cases where elements do not include coordinate shifts, we construct a "periodic table" of such compactifications, organized according to the orbifolding group (order up to 12) and dimension (up to 7). An intriguing connection between supersymmetric orbifolds and G2-structures is explored.Comment: 34 pages, late

The Strength of Non-Perturbative Effects in Matrix Models and String Effective Lagrangians

We present a summary of the results of an explicit calculation of the strength of non-perturbative interactions in matrix models and string effective Lagrangians. These interactions are induced by single eigenvalue instantons in the $d=1$ bosonic matrix model. A well defined approximation scheme is used to obtain induced operators whose exact form we exhibit. We briefly discuss the possibility that similar instantons in a supersymmetric version of the theory may break supersymmetry dynamically.Comment: Latex document, 17 pages, preprint CERN-TH.7356/94, UPR-620