BY AVISHI KHAR
Memories are one of the hardest things to define. In scientific words, it refers to the psychological processes of acquiring, storing, retaining, and later retrieving information. In a more literary and poetic sense of the world, memories are what we either run from or run to and there is no in-between. But in both literature as well as science, we question how memories are made and remembered.
Memories don’t exist in our body physically, they are more of a concept, so how do we remember things? In the most basic language, memories are stored as minute chemical changes at the connecting points between neurons in the brain.
This explanation was given by neuroscientist Santiago Ramón y Cajal, who suggested that the brain stores information by rearranging said connection (or synapses) between the neurons. Neuroscientists have since made an effort to comprehend the physiological alterations connected to memory formation. Yet, it is difficult to visualize and map synapses.
For starters, synapses are quite tiny and closely spaced. These are around 10 billion times smaller than the tiniest thing that a typical clinical MRI can detect. Also, the 1 billion synapses in mouse brains—which are frequently used by researchers to investigate how the brain works—are all the same translucent to opaque tint as the tissue around them.
However, after years of research and experimentation, neuroscientists have made discoveries as to how memories are stored and most of the credit goes to the hippocampus – a complex structure located in the temporal lop of the brain. The hippocampus along with the frontal cortex analyses sensory inputs and decides if they’re worth remembering and these get stored as autobiographic or long-term memories.
The connection of the hippocampus with memory retention was discovered back in 1953, when Henry Molaison, an American patient, had his hippocampus surgically removed to treat his epilepsy. Even though his epilepsy was cured, he was unable to make new memories and store recent information in his brain.
He could however remember events that occurred before the surgery and perform motor tasks, but he wouldn’t remember performing said tasks. His surgery was an extremely important contribution to the development of neuroscience. Neuroscientists came to the conclusion that the hippocampus is important for memory retention and storage but not the permanent site of memory storage and is also not required for motor functions.
Researchers are working on finding out a permanent site for memory storage, but we now know that the hippocampus, the neocortex (memories shift to the neocortex as general knowledge), the amygdala (assign emotional significance to memories) and a few other parts of the brain help us in remembering the memories we so cherish and fear.
