לוח שנה משולב

The study of perceptual decision-making is key to understanding complex cognitive behavior. Two decades of recordings in primate parietal cortex suggest that neurons in the lateral intraparietal (LIP) cortex integrate sensory evidence from upstream neurons (presumably MT) in favor of making a decision. However, the causal role of LIP in decision-making had not been tested directly.
In this talk, I will present recent experiments that tested whether area LIP—which exhibits strong decision-related activity—is causally related to perceptual decision-making. In contrast to the generally accepted model, we found that inactivation in area LIP had no measurable impact on decision-making behavior (despite having exerted effects in a control task). This finding suggests that strong decision-related activity does not guarantee a causal role in decision-making. To better understand the MT-LIP circuit we then applied a Generalized Linear Model (GLM) to simultaneously recorded MT and LIP neurons. We found that much of MT & LIP responses may be interpreted in simple sensorimotor terms, as opposed to appealing to nuanced cognitive phenomena. These results shift our understanding of decision-related activity in the primate brain and motivate new approaches to further dissecting the circuit.

Perception of connected speech relies on accurate syllabic segmentation and phonemic encoding. These processes are essential because they determine the building blocks that we can manipulate mentally to understand and produce speech. Segmentation and encoding might be underpinned by specific interactions between the acoustic rhythms of speech and coupled neural oscillations in the theta and low-gamma band. To address how neural oscillations interact with speech, we used a neurocomputational model of speech processing generating biophysically plausible coupled theta and gamma oscillations. We show that speech could be well decoded from this purely bottom-up artificial network’s low-gamma activity, when the phase of theta activity was taken into account. Because speech is not only a bottom-up process, we set out to develop another type of neurocomputational model that takes into account the influence of linguistic predictions on acoustic processing. I will present preliminary results obtained with such a model and discuss the advantage of incorporating neural oscillations in models of speech processing.

Abstract: Let Rep(GL(m|n)) denote the category of finite-dimensional algebraic representations of the supergroup Gl(m|n). Nowadays the abelian structure (Ext^1 between irreducibles, block description,...) is well understood. Kazhdan-Lusztig theory gives an algorithmic solution for the character problem, and in special cases even explicit character formulas. However we understand the monoidal structure hardly at all (e.g. the decomposition of tensor products into the indecomposable constituents). I will talk about the problem of decomposing tensor products "up to superdimension 0", i.e. about the structure of Rep(GL(m|n))N where N is the ideal of indecomposable representations of superdimension 0.

Toshiya Endo is a professor of Faculty of Life Sciences, Kyoto Sangyo University. He received his PhD degree for his NMR study on snake neurotoxins at Department of Biochemistry and Biophysics, Faculty of Science, the University of Tokyo in 1982. He became an assistant professor at Department of Chemistry, College of Technology, Gunma University in 1982, was promoted to an associate professor of the same department in 1987, and then became an associate professor of Department of Biological and Chemical Engineering, Faculty of Engineering, Gunma University in 1989. In the meantime (1986-1988), he was a visiting scientist at Biocenter, the University of Basel, Switzerland, where he joined Jeff Schatz’s group to start his work on protein import into mitochondria. In 1989, he moved to Nagoya University to become a PI as an associate professor at Department of Chemistry, Faculty of Science, Nagoya University, and became a full professor in 1991 at the same department. In 1996, he became a professor of Department of Chemistry, Graduate School of Science, Nagoya University. In 2003-2008, he was a project-based faculty of the Institute for Advanced Research, Nagoya University. He had been the leader of the Grant-in-Aid for Scientific Research in Priority Area from MEXT, ‘Protein Community’ (2007-2012), and now the recipient of the CREST grant from JST for 2012-2017. After research and education life for 24 years at Nagoya University, he recently moved to Kyoto Sangyo University in April 2014