Challenges of understanding brain function by selective modulation of neuronal subpopulations
- •Lesion-based approaches remain central to many studies of brain function.
- •A common approach for understanding neuronal processing is to reduce complexity by defining subunits and infer their functional roles by selectively modulating them.
- •The selective modulation approach suffers from conceptual and practical limitations, in particular for networks with recurrent structure.
- •We present and discuss the notions of embeddedness and controllability as possible means to overcome these limitations.
Neuronal networks confront researchers with an overwhelming complexity of interactions between their elements. A common approach to understanding neuronal processing is to reduce complexity by defining subunits and infer their functional role by selectively modulating them. However, this seemingly straightforward approach may lead to confusing results if the network exhibits parallel pathways leading to recurrent connectivity. We demonstrate limits of the selective modulation approach and argue that, even though highly successful in some instances, the approach fails in networks with complex connectivity. We argue to refine experimental techniques by carefully considering the structural features of the neuronal networks involved. Such methods could dramatically increase the effectiveness of selective modulation and may lead to a mechanistic understanding of principles underlying brain function.