In his 1923 volume The Prisoner, (and in 1998 Alex Proyas movie Dark city) Where French novelist Marcel Proust describes memory as a “…sort of chemical laboratory.” This apt definition was ahead of its time, as scientists were just learning about the brain’s anatomy. Nearly a century later, neuroscientists are beginning to discover the chemical and molecular pathways responsible for creating and recalling memories.
At Rutgers University, Timothy Otto and his colleagues are delving into the brain’s biochemical activities to determine the ways in which experiences activate genes within brain cells to form lasting memories. The researchers have discovered that the Arc gene and its protein product, also called Arc, play an essential role in the memory formation process.
Such as cytoskeleton. Cytoskeleton is unique to eukaryotic cells. It is a dynamic three-dimensional structure that fills the cytoplasm. This structure acts as both muscle and skeleton, for movement and stability. The long fibers of the cytoskeleton are polymers of subunits. The primary types of fibers comprising the cytoskeleton are microfilaments, microtubules, and intermediate filaments.
Microfilaments are fine, thread-like protein fibers, 3 – 6 nm in diameter. They are composed predominantly of a contractile protein called actin, which is the most abundant cellular protein. Microfilaments’ association with the protein myosin is responsible for muscle contraction. Microfilaments can also carry out cellular movements including gliding, contraction, and cytokinesis. (Cytokinesis is the part of the cell division process)
Microtubules are cylindrical tubes, 20 – 25 nm in diameter. They are composed of subunits of the protein tubulin – these subunits are termed alpha and beta. Microtubules act as a scaffold to determine cell shape, and provide a set of “tracks” for cell organelles and vesicles to move on. Microtubules also form the spindle fibers for separating chromosomes during mitosis. When arranged in geometric patterns inside flagella and cilia, they are used for locomotion.
Intermediate filaments are about 10 nm diameter and provide tensile strength for the cell.
Editors note: Could lead to memory research for elimanating memories (Dark City)
Arc is found in the brain’s hippocampus region (the area involved in many forms of learning), and activates as memories form. “We’ve shown that to form new memories the hippocampus must produce Arc and that blocking Arc production, blocks memory formation and recall,” explains Otto.
The Arc protein (dark spots) gets expressed by the Arc gene when a memory forms in the hippocampus. To zero in on Arc activity in the brains of rats, Otto and his team inject a substance that binds to the Arc gene which are fluoresces and lights up when the hippocampus produces Arc protein. As the genes and proteins light up, they create a map of the cells involved in memory formation. “With the map we can see how a healthy brain works and the brain regions involved in making new and different types of memory,” says Otto.
Knowing how a healthy brain forms memories is an important step to understanding what goes wrong in a range of memory disorders including Alzheimer’s disease and stroke. Considering the public health aspects of his work, Otto notes that “figuring out how to fix these disorders is crucial since the number of brain-related disorders will likely skyrocket as the population increasingly ages.”
So where does the idea of a bug come in?
Elissa D. Pastuzyn, who authored one of the studies, said: “Evolutionary analysis indicates that Arc is derived from a vertebrate lineage of Ty3/gypsy retrotransposons, which are also ancestors to retroviruses.” It’s believed that between 40 per cent and 80 per cent of the human genome was developed thanks to ancient viruses.
Unlike bacteria, which simply live in the body, viruses make active changes to your cells, injecting their own genetic code.
This can often be entirely useless – and sometimes causes harm, including through the reproduction of more viruses – but occasionally we end up with useful modifications. And it seems an ancient virus may have given rise to all human thought – thanks to the Arc gene.