First Complete Wiring Diagram of Animal Nervous System
Group of Researchers at Albert Einstein College of Medicine have described the world’s first complete wiring diagram of an animal’s nervous system – the roundworm Caenorhabditis elegans, which is used worldwide by scientists as a model organism. The study includes adults of both sexes and shows differences between them.
The findings mark a significant landmark in the field of”connectomics,” the effort to map the myriad neural connections within a mind, brain area, or nervous system to find the particular nerve connections responsible for particular behaviors.
The research leader Scott Emmons, Ph.D., professor of genetics and at the Dominick P. Purpura Department of Neuroscience & the Siegfried Ullmann Chair in Molecular Genetics at Einstein said that the structural organization of DNA reveals how genes work, and by analyzing structure of proteins one can identify how enzymes function. Now, with the construction of the nervous system one can study & describe how animals act and the way that neural links go wrong to cause illness.
Scientists have hypothesized that some neurological and psychiatric disorders, such as schizophrenia and autism, are”connectopathies,” which is, problems caused by “faulty wiring.” “This theory is bolstered by the finding that many mental disorders are associated with mutations in enzymes that are thought to determine connectivity,” said Dr. Emmons. “Connectomics has the potential to help us understand the basis of several mental illnesses, possibly indicating avenues for therapy.”
Because C. elegans are tiny organisms with adults being just one millimeter long and consume just about 1,000 cells. It’s simple nervous system made up of a couple of hundred neurons (302 in the hermaphrodite/female gender, 385 from the male) makes it among the greatest animal models for studying the billions-times-more-complex human mind. It was also the first multi-cellular organism whose entire genome was sequenced.
For the new study, Dr. Emmons’ team analyzed fresh roundworm electron micrographs as well as Dr. Brenner’s old ones and pieced them together using specially developed software to create complete wiring diagrams of whole adult animals of both C. elegans sexes. The diagrams include all connections between individual neurons, connections from neurons and tissues and synapses between the muscle cells, together with estimates of the strength of those synapses.
“While the synaptic pathways in the two sexes are substantially similar, a range of those synapses differ in strength, giving a basis for understanding sex-specific behaviors,” said Dr. Emmons. The main gender differences pertain to reproductive purposes: in vulval and uterine muscles along with the motor neurons which control them in the hermaphrodite; and also in a large number of additional neurons, sex muscles, and relations in the tail that create the circuits for copulation in the male. But beyond these, a number of synapses between neurons in central pathways shared by the two genders appear to differ substantially in strength.
“These connected systems function as starting points for deciphering the neural control of C. elegans behavior,” said Dr. Emmons. “Since the roundworm nervous system contains many of the very same molecules as the human nervous system, what we learn about the former can help us comprehend the latter.”
Dr. Emmons is currently analyzing the way the roundworm connectome is encoded by its genome. The above research study was published in the journal Nature.