Plasticity of Sensory Systems
Monday, September 24, 2007
Organizers: Bruce McCandliss, Weill Medical College of Cornell University and Daphne M. Maurer, McMaster University
In domains as diverse as vision, language, social imprinting, and recovery from brain damage, the pervasive notion that critical periods restrict the influence of experience to the early years of development has led to the assumption of limited neural plasticity in adulthood. However, recent studies have revealed remarkable residual cortical plasticity in adults, prompting new questions about the extent to which critical periods might be re-opened, and the ways in which plasticity might be regained during adulthood. This symposium will examine these issues in the context of the visual system – a model system for exploring such issues since the classic work of Hubel and Wiesel. Four world-renowned researchers will present pioneering work on the specific mechanisms of experience-dependent changes linked to adult learning and structural damage, as well as mechanisms that drive and regulate critical periods. Understanding the interplay between the mechanisms that allow plastic change during adulthood and those that limit plasticity to early periods of development may aid translational efforts to remediate the persistent negative impact of early abnormal visual development, such as amblyopia. Such findings may also provide a model system for understanding the developmental limitations on learning and plasticity in other neural systems.
Agenda
6:00-6:15 PM
Introduction
Daphne Maurer, McMaster University
6:15-6:45 PM
J. Anthony Movshon, PhD, New York University
Sensitive Periods in Visual Development
6:45-7:15 PM
Brian A. Wandell, PhD, Stanford University
The Human Visual Pathways: Maps and Plasticity
7:15-7:30 PM
Coffee Break
7:30-8:00 PM
Charles D. Gilbert, PhD, The Rockefeller University
Learning to See: Neural Mechanisms of Perceptual Learning
8:00-8:30 PM
Takao K. Hensch, PhD, Harvard University
Unlocking Brakes on Plasticity
8:30-9:00 PM
Panel Discussion
Moderator: Bruce McCandliss, Weill Medical College of Cornell University
9:00-10:00 PM
Reception
Abstracts
J. Anthony Movshon, PhD, New York University
The classical view of visual development is that there is a single early sensitive period, during which functional development takes place and the system is vulnerable to environmental influences. After the sensitive period ends, the system was thought to crytallize into its adult form. A closer examination of the course of visual development suggests, however, that visual function develops in a cascaded series of sensitive periods, with relatively "higher" functions developing later, well into what was originally thought to be a period of complete maturity. The hierarchical organization of the primate extrastriate visual system makes it natural to think that this cascade of functional development might reflect an anatomical cascade, with lower areas and their associated functions maturing earlier, and higher areas maturing later, and there is some physiological and anatomical evidence for this cascade. In fact, the period of visual development for some higher functions is so prolonged that the sensitive period never really ends. So while the old idea of a sensitive period with a definite termination may serve well for primary cortex, a very extended period of plasticity for higher cortical areas may merge seamlessly and imperceptibly into the adult state of the visual system, in which many forms of adaptability and plasticity are evident.
Funded in part from the James S. McDonnell collaborative network for Critical Period Re-Examination (Brain CPR)