The human brain acts as a control center for many basic and complex functions of the body, with many of these processes not fully understood, according to a ScienceDirect article. Eve Marder (BIOL) and her lab at Brandeis University are working to help understand brain functions better.
Marder’s lab, which works to classify central oscillator circuits in the brain, was able to uncover cells in lobsters and crabs, found in the stomatogastric ganglion, that create oscillatory activity to govern the rhythmic motion of the digestive tract, according to a ScienceDaily report.
As reported by ScienceDaily, central oscillators are vital to bodily functions in mammals because they are responsible for maintaining rhythmic firing patterns. Bodily functions such as walking, chewing and breathing are all patterns that need to be regulated and consistent. The rhythmic firing patterns of neurons within mammalian brains are responsible for the internal tempo which keeps those functions consistent, the article noted.
While it has been and is widely considered true, prior to the research proving their placement, that oscillatory cells are responsible for rhythmic behavior in mammals, it was too difficult to pinpoint the exact location of the cells responsible, according to ScienceDaily. For example, bodily functions such as walking were believed to have an oscillator connected throughout the spinal cord. The large range of cells and neurons related to that part of the body was difficult to sort through to find the exact cells responsible for that rhythmic behavior, as described in the article.
Marder’s lab was able to find cells within the brains of crabs and lobsters with a more precise scope, unlike that of other labs at the time. As reported in a BrandeisNOW article about Marder’s research, “Marder pioneered the studies that introduced neuromodulation.” Neuromodulation is the process by which neurons can be changed and highlighted to identify which are and are not firing by using chemical substances to reach them, as written in BrandeisNOW.
The BrandeisNOW article explained that neuromodulation differs from prior processes which seek to highlight firing neurons because previous processes had to go through synaptic contacts with other neurons. This limited the scope in which scientists could identify and properly determine which cells and neurons in the brain were responsible for exactly what bodily functions, as the article described.
Marder’s lab used this technique to identify the central oscillator circuits in invertebrates, lobsters and crabs in this case, written about in BrandeisNOW. However, researchers at the Massachusetts Institute of Technology have been able to use this method of identifying neurons to properly identify an oscillator in a mammal, according to ScienceDaily.
Specifically, they were able to identify the oscillator responsible for whisking in mice. Whisking is the rhythmic process by which mice and rats in particular are able to move their whiskers. Whisking allows for rodents to partake in a plethora of different functions such as object touch and discrimination, navigation, attacking, swimming and social touch from other rodents, as professor Suzanne E. Gregoire, an animal psychologist at the University of Connecticut, explains.
According to Fan Wang, an MIT professor of brain and cognitive sciences and a member of MIT’s McGovern Institute for Brain Research, to provide these vital functions the whiskers on mice are recorded to extend and retract at a frequency that is roughly 12 cycles per second. In order to discover where the whisking oscillator lies in the brain of a mouse, the researchers at MIT had to work from the outside in. They began with the motor neurons that are responsible for the movement of whisker muscles. But to uncover what neurons are responsible for the tempo at which those neurons fire, they had to go further, as Wang explained.
They employed the use of a modified rabies virus. This virus, Wang elaborated, when distributed to the mice, had the goal of increasing the time in between neural responses. Thus, the virus would slow down rhythmic activities if it targeted the correct neurons, as described by Wang.
The MIT researchers found that, consistent with previous studies, damage to the brainstem reduced whisking. This is the first time that an oscillator, responsible for rhythmic behavior, in mammals has been completely identified, according to ScienceDaily. Starting with work in Marder’s lab at Brandeis University, what were previously undiscovered secrets of the brain are slowly being revealed, as expounded in ScienceDaily.