While scientists have shown that the brain transmits signals electrically, the manner by which these signals turn into thoughts and feelings is not well understood. Understanding how the brain processes, stores and recalls information is a subject of ongoing research, complicated by the sheer complexity of the human brain.
A full theory on how the brain functions would have to be able to include observations and data observed on molecular, cellular, synaptic, circuit, systems, computational and psychological levels; until recently, most scientists treated these levels separately. The neural complexity of the brain presents an additional challenge; the human brain contains more neurons than there are stars in the galaxy, with an additional 1 million new connections between these neurons formed daily.
Ongoing research in understanding the human brain focuses on mapping and diagramming the organ, so as to better understand the signalling pathways used by the brain. This is complicated by the small size and large number of neurons, although recent advancements have made it possible to individually target specific neurons and pathways. A major current problem involves increasing the spatial and temporal resolution of neural imaging. Current methods can only gather limited amounts of data, hampering efforts to completely understand neural pathways.