Most scientists agree that the network of brain connections is too complex to describe; however, molecular biology and computing methods have improved significantly the ability to describe the connection between the neural nodes. Therefore, the National Institutes of Health have announced a $30 million plan to map the human “connectome.”
In a study recently published in the Proceedings of the National Academy of Sciences, a team of researchers from the University of Southern California (USC) map a small area of the rat brain, using a new method for tracing brain circuits.
The research, conducted by neuroscientists Richard H. Thompson and Larry W. Swanson, traced circuits running through a “hedonic hot spot” related to food enjoyment. Their results show the circuits as patterns of circular loops, suggesting that at least in this part of the rat brain, the wiring diagram looks like a distributed network. “We started in one place and looked at the connections. It led into a very complicated series of loops and circuits,” said Swanson.
The circuit tracing method allows the study of incoming and outgoing signals from any two brain centers. Thompson, a research assistant professor of biological scinces at USC, invented and refined the method over a span of eight years. This study differs from other tracing studies that focus only on one signal, in one direction, at one location.
Neuroscientists are split between a traditional view that the brain is organized as a hierarchy, with most regions feeding into the “higher” centers of conscious thought, and a more recent model of the brain as a flat network. Some use the Internet as an analogy to our brain – a vast network based on numerous nodes. According to the team’s study, they clearly prefer the latter. “It’s not an organizational chart,” said Swanson, “there’s no top and bottom to it. There is an alternate model. It’s not proven, but let’s rethink the traditional way of regarding how the brain works.”
The Internet model would explain the brain’s ability to overcome local damage.
“You can knock out almost any single part of the Internet and the rest of it works,” said Swanson. Furthermore, he claims that the methods he utilized will help recognize new patterns. “[We] can look at up to four links in a circuit, in the same animal at the same time. That was our technical innovation,” he said.
The team’s study could help mark the connections between specific parts of the brain, but not all of them. “There are usually alternate pathways through the nervous system. It’s very hard to say that any one part is absolutely essential,” said Swanson. When asked to about a crucial element that might worth focused research, he chooses the cortex. “The part of the brain you think with, the cortex, is very important, but it’s certainly not the only part of the nervous system that determines our behavior.”
TFOT has also covered the Internal Brain Wave Clock, discovered at the Massachusetts Institute of Technology, memory encoding methods researched at the University of California at Santa Barbara, and a new study suggesting that our brain, not eyes, see color.
For more information about the brain’s wiring, see University of Southern California’s press release.
