Learning and memory are crucial to our functioning as humans. From childhood to our adult life we use our neural abilities to remember, learn and sometimes unlearn.
It turns out that the structure and function of brain centers responsible for learning and memory in a wide range of invertebrate species may possibly share the same fundamental characteristics, according to a new study published in the journal Current Biology
and performed by University of Arizona neuroscientists Nicholas Strausfeld, Regents' Professor in the Department of Neuroscience, part of the UA's School of Mind, Brain and Behavior, and Gabriella Wolff.
The brain centers in question are paired, lobed structures first discovered in insects and known as mushroom bodies. These centers occur in the forebrains of arthropods, as well as in marine worms and flatworms.
Because the commonalities between mushroom bodies in different species are so striking, there has been a debate about whether these structures evolved independently or whether they derive from a common ancestor. Strausfeld's and Wolff's analysis revealed a ground pattern organization that is common to mushroom bodies in all of the investigated species, suggesting its inheritance from an ancient ancestor, possibly 600 million years in the past.
"This ground pattern of mushroom bodies is ubiquitous across a broad range of species," said Wolff, a graduate student in the Neuroscience Graduate Interdisciplinary Program. "If we wanted to emulate a learning and memory center in an artificial intelligence or a robot, this is where we would start."
Strausfeld and Wolff looked at both the neuroanatomy and chemical composition of mushroom bodies in numerous species belonging to two major groups of invertebrates: Ecdysozoa, which includes insects, crustaceans and other arthropods such as scorpions and horseshoe crabs; and Lophotrochozoa, which includes mollusks, flatworms and segmented worms.
Using a variety of chemical staining techniques, Strausfeld and Wolff were able to study and compare the neuroanatomy of different species in great detail. Not only were the characteristics of individual mushroom body neurons the same across species, their organization among each other was the same as well. The researchers found that parallel bundles of neuronal fibers in the mushroom bodies in each species are arranged in similarly structured, orthogonal networks typical of learning circuits.