Orbital Frontal Cortex Projections to Secondary Motor Cortex Mediate Exploitation of Learned Rules.

Animals face the dilemma between exploiting known opportunities and exploring new ones, a decision-making process supported by cortical circuits. While different types of learning may bias exploration, the circumstances and the degree to which bias occurs is unclear. We used an instrumental lever press task in mice to examine whether learned rules generalize to exploratory situations and the cortical circuits involved. We first trained mice to press one lever for food and subsequently assessed how that learning influenced pressing of a second novel lever. Using outcome devaluation procedures we found that novel lever exploration was not dependent on the food value associated with the trained lever. Further, changes in the temporal uncertainty of when a lever press would produce food did not affect exploration. Instead, accrued experience with the instrumental contingency was strongly predictive of test lever pressing with a positive correlation between experience and trained lever exploitation, but not novel lever exploration. Chemogenetic attenuation of orbital frontal cortex (OFC) projection into secondary motor cortex (M2) biased novel lever exploration, suggesting that experience increases OFC-M2 dependent exploitation of learned associations but leaves exploration constant. Our data suggests exploitation and exploration are parallel decision-making systems that do not necessarily compete

The role of companions in outpatient seizure clinic interactions: A pilot study

Purpose: This study explored contributions that patients' companions (seizure witnesses) make to interactions in the seizure clinic and whether the nature of the companions' interactional contributions can help with the differentiation of epilepsy and psychogenic nonepileptic seizures (PNES). Methods: Conversation analysis methods were used to examine video recordings and transcripts of neurologists' interactions with patients referred to a specialist seizure clinic and their companions. Results: The companions' behavior correlated with interactional features previously observed to distinguish patients with epilepsy from patients with PNES. Patients with PNES, but not those with epilepsy, tended to exhibit interactional resistance to the doctor's efforts to find out more about their seizure experiences and, thereby, encouraged greater interactional contribution from companions. Conclusion: The contributions that companions make (in part, prompted by patient's interactional behavior) may provide additional diagnostic pointers in this clinical setting, and a number of candidate features that may help clinicians distinguish between epilepsy and PNES when the patient is accompanied by a seizure witness are described. However, companion contributions may limit the doctor's ability to identify linguistic and interactional features with previously demonstrated diagnostic potential in the conversational contributions made by patients themselves. To help offset potential diagnostic losses, doctors may need to explicitly discuss the role of the companion in the consultation when a seizure witness (or another companion) accompanies the patient

How should we interpret the two transport relaxation times in the cuprates ?

We observe that the appearance of two transport relaxation times in the various transport coefficients of cuprate metals may be understood in terms of scattering processes that discriminate between currents that are even, or odd under the charge conjugation operator. We develop a transport equation that illustrates these ideas and discuss its experimental and theoretical consequences.Comment: 19 pages, RevTeX with 8 postscript figures included. To appear in ``Non Fermi Liquid Physics'', J. Phys:Cond. Matt. (1997

Singular value decomposition applied to compact binary coalescence gravitational-wave signals

We investigate the application of the singular value decomposition to compact-binary, gravitational-wave data-analysis. We find that the truncated singular value decomposition reduces the number of filters required to analyze a given region of parameter space of compact binary coalescence waveforms by an order of magnitude with high reconstruction accuracy. We also compute an analytic expression for the expected signal-loss due to the singular value decomposition truncation.Comment: 4 figures, 6 page

Enhanced Tissue Integration During Cartilage RepairIn VitroCan Be Achieved by Inhibiting Chondrocyte Death at the Wound Edge

Objective: Experimental wounding of articular cartilage results in cell death at the lesion edge. The objective of this study was to investigate whether inhibition of this cell death results in enhanced integrative cartilage repair. Methods: Bovine articular cartilage discs (6mm) were incubated in media containing inhibitors of necrosis (Necrostatin-1, Nec-1) or apoptosis (Z-VAD-FMK, ZVF) before cutting a 3mm inner core. This core was left in situ to create disc/ring composites, cultured for up to 6 weeks with the inhibitors, and analyzed for cell death, sulfated glycosaminoglycan release, and tissue integration. Results: Creating the disc/ring composites resulted in a significant increase in necrosis. ZVF significantly reduced necrosis and apoptosis at the wound edge. Nec-1 reduced necrosis. Both inhibitors reduced the level of wound-induced sulfated glycosaminoglycan loss. Toluidine blue staining and electron microscopy of cartilage revealed significant integration of the wound edges in disc/ring composites treated with ZVF. Nec-1 improved integration, but to a lesser extent. Push-out testing revealed that ZVF increased adhesive strength compared to control composites. Conclusions: This study shows that treatment of articular cartilage with cell death inhibitors during wound repair increases the number of viable cells at the wound edge, prevents matrix loss, and results in a significant improvement in cartilage-cartilage integration