A study by New York University (NYU) scientists has concluded that memory, rather than being a complete store of past events, is composed of a vast repertoire of coexisting time windows.
Most memories last seconds before they are forgotten, but some last a lifetime. However, the scientists Thomas Carew and Nikolay Kukushkin have concluded that rather than going from short term to long term, both types of memories coexist.
So, for example, a familiar musical piece is experienced simultaneously through the short-term memory of the few notes just heard and the long-term memory of listening to the piece in the past. Both retain information about the past, they write, and both shape perception in the present.
“Much like sound is broken down by the auditory system into many discrete bins of frequencies that are perceived simultaneously, an experience as a whole is parsed by the brain into many ‘time windows’ that collectively represent the past,” said Carew, a professor in NYU’s Center for Neural Science and dean of the Faculty of Arts and Science.
As a result of their research, Carew and Kukushkin believe memory cannot be restricted to a defined object or state; instead, it is fundamentally structured in terms of time.
The scientists note that brains of living organisms – as diverse as sea slugs and humans – have the capacity to represent experience on many timescales, simultaneously recalling events occurring over years, hours, and milliseconds.
“Time is the only physical variable that is ‘inherited’ by the brain from the external world,” the scientists conclude. “Thus, memories must be ‘made of time,’ or, more precisely, of temporal relationships between external stimuli.
“In effect, the entire biological utility of memory relies on the existence of many dimensions of homeostasis, some shorter-term and some longer-term. The many timescales of memory represent many timescales of past experience and must be simultaneously available to the organism to be useful.”