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Rise and fall of modular orthodoxy
1Department of Psychiatry, New York University Medical Center, NY 10016, USA.
Journal of Clinical and Experimental Neuropsychology
|April 1, 1995
Summary
Brain lesion studies often overstate cortical modularity. Evidence suggests a continuous neocortical geometry, with modularity being an emergent property rather than intrinsic, especially in the left hemisphere.
Area of Science:
- Neuroscience
- Cognitive Science
- Neuroanatomy
Background:
- The concept of cortical modularity, based on focal brain lesions, has been a dominant paradigm in neuroscience.
- However, the rarity and selectivity of dissociations from focal lesions challenge this view.
- Understanding brain organization requires considering the totality of lesion effects.
Purpose of the Study:
- To re-evaluate the premise of cortical modularity in light of lesion evidence.
- To propose an alternative model of neocortical organization.
- To differentiate between intrinsic and emergent modularity.
Main Methods:
- Critical analysis of lesion studies and their interpretation.
- Theoretical modeling of brain function.
- Comparative analysis of thalamic and cortical organization.
Main Results:
- Focal lesion dissociations are rare and their importance is overrated.
- Neocortical function is better described by a continuous, graded geometry than strict modularity.
- Strong intrinsic modularity is characteristic of the thalamus, not the cortex.
- Weak, emergent modularity arises from cognitive skill routinization and may be asymmetric.
Conclusions:
- The neocortex evolved towards interactive principles, escaping strong modularity.
- Emergent modularity, particularly in the left hemisphere, reflects functional specialization.
- The right hemisphere may be largely amodular, supporting a more integrated processing style.