Memory and the Brain: Sequential Memory Capacity and Neural Architecture

It is real that the brain works more during recall. Extremely long sequential memories. Humans are capable of remembering extremely long sequences like all of Hamlet's lines, but the brain has no architecture that seems to support sequential memorization. An interesting characteristic of human memory is that it can show enormous sequential competence. Humans are capable of remembering exactly extremely long text sequences. We have an example in the case of actors who successfully memorize all 1476 lines of Hamlet's role. But the brain doesn't seem to have an architecture that could conceive such capacity. Each neuron is connected to more than 1000 other neurons according to an architecture that seems much more parallel than sequential. In general, it's not possible to give an ordering to structures of this type and define a successive neuron or a preceding neuron. So, how could a sequence of 1476 lines ever be stored in a brain? We certainly cannot imagine that individual words are stored on individual neurons, and that once the initial neuron is found, the brain continues to travel along a chain path that constantly leads to the next neuron. Given such neural architecture, we cannot easily imagine a way in which very long sequences can be stored and retrieved.

Large memory, same brain. People with dramatically higher recall of episodic memories don't seem to have a larger brain or cerebral superiority that could explain the phenomenon. In the case of hyperthymesia or highly superior autobiographical memory we have a rare ability of almost all things that happened to them in adult age. Famous is the case of the mnemonist described by Luria, but nowadays at least sixty cases are known, documented and studied worldwide. The first recent case documented by science is the case of Jill Price: Price was the first person to be diagnosed with what is now known as highly superior autobiographical memory, or HSAM, a condition she shares with about 60 other known people. She can remember most days of her life with the same clarity with which the rest of us remember the recent past, with a mix of broad brushstrokes and sharp details. Now, Price remembers the day of the week for every date since 1980; she remembers what she was doing, who she was with, where she was on each of these days. She can actively recall a memory from 20 years ago with the same ease as a memory from two days ago, but her memories are also activated involuntarily. Jill Price has an ordinary head that is smaller than...