The goal of this research is to establish the extent to which the adult brain is plastic even in adulthood and to determine the functional consequences of such plasticity. Over the past year we have focused on plasticity following the loss of input to particular regions of the brain, including visual and somatosensory cortex.? ? People with macular degeneration lose central vision due to damage of the retina. But what happens to the parts of the brain that are specifically involved in processing central visual stimuli? Do those parts of the brain simply become inactive or can they take on new function? Using functional magnetic resonance imaging (fMRI), we have previously shown in two participants with macular degeneration that the parts of the brain specifically involved in processing central vision become responsive to visual stimuli in peripheral vision. We have now extended these findings to three new participants with macular degeneration and further shown that the change in functional properties occurs only when there is complete loss of central vision: in two participants with severely disrupted central vision but with some residual vision, we found no evidence for activation by peripheral stimuli of brain areas selective for central vision. Having shown brain reorganization following loss of visual input, we are now addressing the functional consequences of that reorganization.? ? Following limb amputation, the majority of people report phantom sensations in their missing limb, often painful sensations. One current theory is that the phantom limb pain arises as a result of cortical reorganization. We are currently monitoring brain activation with fMRI in unilateral limb amputees over a period of four weeks while they undergo therapy to treat the phantom limb pain. The therapy being used is mirror therapy: each day the participants view their intact limb in a mirror giving the impression of their amputated limb moving. In particular we are trying to establish whether the presence of phantom limb pain correlates with cortical reorganization in the somatosensory cortex (similar to that observed in our participants with macular degeneration) and whether the therapy works by reducing the extent of cortical reorganization.? ? Establishing the degree and consequences of plasticity in the adult cortex provides important insights into the potential for rehabilitative brain therapies.
| Beeck, Hans P Op de; Baker, Chris I (2010) Informativeness and learning: Response to Gauthier and colleagues. Trends Cogn Sci : |
| Baker, Chris I; Dilks, Daniel D; Peli, Eli et al. (2008) Reorganization of visual processing in macular degeneration: replication and clues about the role of foveal loss. Vision Res 48:1910-9 |
| Baker, Chris I; Liu, Jia; Wald, Lawrence L et al. (2007) Visual word processing and experiential origins of functional selectivity in human extrastriate cortex. Proc Natl Acad Sci U S A 104:9087-92 |
| Baker, Chris I; Hutchison, Tyler L; Kanwisher, Nancy (2007) Does the fusiform face area contain subregions highly selective for nonfaces? Nat Neurosci 10:3-4 |
| Op de Beeck, Hans P; Baker, Chris I; DiCarlo, James J et al. (2006) Discrimination training alters object representations in human extrastriate cortex. J Neurosci 26:13025-36 |
