The "dark" matter of the human brain

The human brain contains tens of billions of neurons, but are they all really needed in our everyday life? The notion of eloquence, used in neurosurgery to distinguish between important brain tissue and brain tissue that can be removed, suggests a negative answer. However, there is no proof that such idle brain areas without any role really exist. To understanding the human brain scientists typically follow one main strategy. They focus on one function related to perception, movement or cognition and searches for brain areas associated with it. Following this strategy, visual function could be associated with regions of the occipital lobe of the brain, long-term memory with the hippocampus, emotion with the amygdala, etc. The main outcome of such approach is a functional map of the brain, in which specific brain regions are associated with specific functions. Although sensible, this approach remains one-sided because of its primary focus is on functions rather than areas. As a consequence, knowledge is gained only about those brain regions which can be associated with specific functions, leaving the remaining gray matter out of the picture. In this project we will identifying gray matter regions whose contribution to perception, cognition, and behavior remains unknown. To achieve this, we will use the large amount of data available through decades of research on the human brain. We will flip the conventional approach of mapping functions to brain areas and instead focus on the brain areas themselves. We will create a complete map of the gray matter of the human brain and divide it into a fine grid of individual locations. For every location, we will search for functions that have been associated with it. As a result, the project will yield a knowledge map of the human brain, highlighting the dark spots, i.e., those gray matter locations that have not been associated with any function. Identifying these dark spots is the first step in their further investigation. This investigation should focus on tackling their functional role or confirming the absence thereof. A detailed map of such functionless brain areas will also be useful in neurosurgery practice. The current project takes a cardinally different approach to understanding the brain and its relationship with mind and behavior, making the brain, rather than the mental processes, the starting point and the reference frame of the investigation. The project will yield a knowledge map of the human brain that will guide future research. Furthermore, confirming the existence of idle gray matter (i.e., areas without a function) will give rise to new questions about their broader evolutionary purpose.