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Kevan AC Martin
Of all brain structures, the neocortex (80% of our brain volume) is arguably the most critical to what makes us human and allows us to create the complex societies in which we live. This is an apparent paradox, because from mouse to man the local circuits in the 2mm thick sheet of the neocortex appear to be very similar, as captured in the term ‘canonical circuits’. A resolution lies in considering the overall physical organisation of the cortical sheet, because this defines a coherent logic of what we call it’s ‘behavioral architecture’. By mapping the whole matrix, we can uncover a coherent and conceptually simple picture of how the interrelationships of evolution, development, and brain organization combine to allow effective behaviors to evolve and to be expressed.
Kevan A.C. Martin is a founding Director of the Institute of Neuroinformatics, Zurich, Switzerland, Emeritus Professor of Systems Neurophysiology at the University of Zurich and the Swiss Federal Institute of Technology (ETH), and he is a former EP Abraham Cephalosporin JRF. His research is on the structure and function of the neocortex. With Rodney Douglas, he developed the concepts of ‘canonical circuits’ and ‘behavioral architecture’ to describe the common principles underlying the circuits and computations that are found across the cortical sheet of all land mammals. One of his abiding fascinations is with the physical basis of thought and performance. His own physical performances are expressed as a member of 4-Brain, a formation skydiving team that competes in Switzerland, and riding a 1936 Ariel Square Four motorcycle.
Working memory describes the ability to maintain and manipulate information that is no longer available in the environment. It provides a flexible mental workspace, and a scaffold for coherent and time-extended behaviour. As a consequence, a central and longstanding theme in cognitive neuroscience has been to delineate the brain mechanisms that support working memory. Since the 1970s, the predominant theoretical view has been that working memories are encoded in the persistent spiking activity of neurons in the prefrontal cortex. However, recent studies have challenged this classic view by demonstrating that memories can also be maintained in the absence of persistent activity in so-called “activity-silent” brain states (e.g., via short-term synaptic plasticity). At the current stage, the precise contributions of activity-based and activity-silent states to working memory remain unknown. In this seminar, I will present my recent research that has tackled this question via a combination of non-invasive brain recordings, pattern classification, and mathematical modelling to show that the two brain states co-exist and afford different aspects of working memory.
Paul is a postdoctoral fellow at the Department of Experimental Psychology at the University of Oxford and at the Stanford Neuroscience Institute. His work is funded by the Wellcome Trust and investigates the functional and brain mechanisms that underpin human memory. Before arriving in Oxford, Paul obtained his Diploma at the Humboldt University in Berlin, his Ph.D. at Ghent University in Flanders, and then spent one year as a postdoc in the United States at the Duke Institute for Brain Sciences.