Determining how feature maps in the cerebral cortex adapt to sudden, f
ocal damage is important for gaining a deeper understanding of neurolo
gical illnesses such as stroke. In this paper we describe a neural mod
el of the region of primary sensory cortex related to upper extremity
proprioception, and show how the feature map there reorganizes followi
ng a simulated lesion. A perilesion zone with decreased activity appea
rs and then gradually expands with time. These results differ from tho
se seen with previous models of cortical lesions, and offer an alterna
tive mechanism to the ''ischemic penumbra'' seen in certain types of s
troke.