Past events

A multitude of experiments over the past century have yielded deep insights into the cellular and synaptic organization of the microcircuitry of the neocortex and its possible role as a functional unit - a column of cells across 6 layers. The available data is, however, not standardized, is highly fragmented and often conflicting. More importantly, there are large gaps in our knowledge requiring an impractical number of experiments to fill. We therefore developed a strategy to accelerate a comprehensive analysis of the neocortical column by attempting to reconstruct it from partial information. We performed a spectrum of standardized biological experiments on strategic cellular and synaptic properties of the microcircuitry of the somatosensory cortex of a young rat and gathered further relevant data from previously published studies. We developed a generic supercomputer-based platform to build and simulate biologically-detailed brain models, and attempted to reconstruct a first draft of a unifying model at the cellular level of detail. The model integrates and unifies most of the current data, significantly predicts missing data, and provides a broad range of new insights into the structural and functional organization of neocortical microcircuitry. The model also serves as a virtual specimen for a new generation of simulation-based experimentation that can accelerate an integrated understanding of the cellular and synaptic basis of neocortical function.

Cognition materializes in an interpersonal space. The emergence of complex behaviors requires the coordination of actions among individuals according to a shared set of rules. Despite the central role of other individuals in shaping our minds, experiments typically isolate human or animal subjects from their natural environment by placing them in a sealed quiet room where interactions occur solely with a computer screen. In everyday life, however, we spend most of our time interacting with other individuals. In the talk I will argue in favor of a shift from a single-brain to a multi-brain frame of reference. I will present a series of studies aimed at characterizing the brain-to-brain coupling during real life social interaction. The data suggest that in many cases the neural processes in one brain are coupled to the neural processes in another brain via the transmission of a signal through the environment. The brain-to-brain neural coupling exposes a shared neural substrate that exhibits temporally aligned response patterns across communicators. The recording of the neural responses from two brains opens a new window into the neural basis of interpersonal communication, and may be used to assess verbal and non-verbal forms of interaction in both human and other model systems.

Any physical device, including computers, when comparing A to B, must send the information to point C. Explanations of brain processing take such a convergence for granted thus generating models relying on increasingly converging hierarchical streams. Such models, however, consistently fail to explain many perceptual phenomena. To see whether the brain, at times, can compare (integrate, process) events that take place at different loci without sending the information to a common target, I performed experiments in three modalities, somato-sensory, auditory, and visual, where 2 different loci at the primary cortex were stimulated. Subjects were able to integrate inputs in time and space affecting small separate cortical loci. The ability to correlate activity between loci was independent of cortical distance up to 2-4 cm. Given the organization of sensory cortex where localized responses in primary cortex do not interact while convergence in downstream areas results in loss of individual stimulus identity and in decreasing selectivity to elementary stimuli, those results cannot be explained by conventional convergence models. We must thus assume a non-converging mechanism whereby two (or more) activated cortical loci can be integrated without sending information via axons into another downstream integrating site. Once we allow for such a non-converging mechanism, many perceptual phenomena can be viewed differently. Object recognition and representation is such a phenomenon that, I suggest, does not result from hierarchical convergence of cells with ever-increasing feature selectivity but rather from parallel interactions between various visual and non-visual areas. If my hypothesis of the brain ability to relate activity taking place at separate loci without using convergence-by-wires is correct, it implies that the brain can use heretofore unconsidered (unknown?) parallel processing and that conventional models, including computer programs, would not be able to capture many brain processes.