News & Events
Mar2112:00pmMetcalf Research Building
Michael S. Goodman ’74 Memorial Seminar Series. Perception & Action Seminar Series. Speaker: Charles Gilbert, The Rockefeller University. Title: Visual Cortical Dynamics. Abstract: Vision is an active and dynamic process. The strategy our brain uses to parse scenes and recognize objects depends on our previous experiences. Our interpretation of visual scenes requires an interaction between internal representations of object properties acquired through experience and the immediate information coming from the retina. At the level of brain circuitry this process involves an interaction between long range and local cortical connections and causes neurons to act as adaptive processors that are able to assume different functional states according to the task being executed. The encoding of information acquired through experience is mediated by plastic changes in cortical circuits. Though the plasticity of certain brain circuits is limited to a critical period in early postnatal life, others retain the capacity for experience dependent change throughout life. Adult plasticity can be seen all cortical areas, with rapid and massive modification of cortical connections, involving exuberant outgrowth of new axon collaterals and a parallel process of pruning of both existing and newly grown axon collaterals. The circuitry of the adult cortex therefore is under a continual long term process of modification as we assimilate new experiences, and short term dynamics as we analyze the constituents of visual scenes. These mechanisms are common to all regions of the brain, and when disrupted may account for behavioral disorders such as autism and schizophrenia. Co-sponsored by CVR
Mar212:00pmMetcalf Research Building
Michael S. Goodman ’74 Memorial Seminar Series. LingLangLunch Seminar Series. Speaker: Jason Shaw, Yale University. Title: Phonological control of time. Abstract: Speech unfolds in time in ways that are language-specific and seem to be conditioned in part by phonological structure. However, language-specific timing patterns are generally still situated outside the scope of phonological theory. Articulatory Phonology (AP) is an exception in this regard. In AP, language-specific timing patterns are modelled in terms of coordination between articulatory gestures, primitive units of phonological contrast. The network of coordination relations between gestures drive articulatory movements in speech. In this talk, I’ll present two case studies that present apparent challenges to AP and show how the challenges can be resolved. The first case study presents Electromagnetic Articulography data tracking articulatory movements in Mandarin Chinese. The key finding is that the relative timing between consonants and vowels in Mandarin varies systematically with token-to-token variability in the spatial position of the tongue, a pattern which is not expected under feed-forward timing control, as in AP. The second case study is a field-based ultrasound study of lenition in Iwaidja, an Australian aboriginal language. In intervocalic position, velar approximants in Iwaidja variably delete. The challenge for AP is that temporal duration is partially preserved even as the velar consonant is completely lost. Developing a theoretical account of these patterns in AP reveals dimensions over which phonological systems shape language-specific variation in timing.
Apr33:00pm - 5:00pmFriedman Hall
Age-related changes in bottom-up and top-down processing mediating visual recognition, Location 190 Thayer Street, Friedman Auditorium