Reorganization in Adult Primate Sensorimotor Cortex: Does It Really Happen?
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- author-supplied keywords
- Tamar R. Makin
- Jorn Diedrichsen
- John W. Krakauer
- Reorganization in Adult Primate Sensorimotor Cortex: Does It Really Happen?
- Cognitive Neuroscience
- W. W. Norton & Company
The primary somatosensory (S1) and motor (M1) cortices are somatotopically organized, with distinct brain areas receiving information from—and controlling the movements of specific body parts. But once this specialized organization has formed, can it be altered to support the changing needs of the organism? In this chapter, we reexamine the extent to which reorganization of the cortical hand representation occurs in the adult primate brain, with respect to both physiology and behavior. We review seminal findings reporting changes in the cortical maps of humans and nonhuman primates, which have been interpreted as evidence of brain reorganization: a qualitative change in the response of neurons. For example, a hand sensory area now responds to tactile stimulation of the face. We focus on three potential triggers for brain reorganization: changed input (due to training), input loss (due to amputation), and substrate loss (due to stroke). We review recent research demonstrating that the canonical functional organization in S1 and M1 is more resilient than originally assumed. Instead, experience or injury-dependent cortical map changes more likely result either from the unmasking of preexisting cortical connections or from subcortical reorganization, rather than true cortical reorganization. Finally, we examine whether cortical map changes, whatever their physiological origin, have any causal adaptive or maladaptive consequence on perception and action and conclude that they do not. Overall, our review suggests that although the adult brain can change based on experience or injury, cortical reorganization does not need to be invoked as the driving mechanism.
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