Self and Memory 231“9x6” b2726 Self and the Phenomenon of Life: A Biologist Examines Life from Molecules to Humanity10.11 Newton, Einstein, Kant and the Little Hippocampus
Space and time are properties of our universe that have baffled mankind
since the beginning of history. In the classical mechanics of Newton, space
and time are taken to be rigid and immutable frameworks within which
matters are embedded, and space–time presumably remains unchanged
even if devoid of matter and energy.^43 Contrary to this absolutist view,
Einstein proposed that space–time is an inter-related four-dimensional
continuum that changes with respect to the velocity of an observer. For
example, a clock that travels at very high speed appears to tick slower to a
stationary observer (time dilation), and the length of a fast-moving object
appears shorter (in the direction of travel) to the same observer (length
contraction). In Einstein’s view, the perception of space and time is “in
the eye of the beholder”.^44 Kant took a bolder stance in dealing with this
issue. Kant posited with his a priori notion that space and time are innate
functions of the mind to make sense of the outside world. Although
Kant’s idea was never clearly formulated, the fact that he involved the
participation of the observer had a hint of prescience.^45 But what does
this have to do with the hippocampus, the seahorse-shaped structure of
the brain that rolls inward out of sight from the surface?
From a micro-structural viewpoint, memory is a matter of synap-
tic plasticity, the strengthening or weakening of neuronal connections.
From a macro-structural viewpoint, memory is a product of systems
interaction among different parts of the brain where these microscopic
changes take place. At any given moment the conscious brain engages
multiple sensory modalities to perceive the external world, resulting in
transient changes in various cortical areas and circuits. As soon as each
fleeting moment of consciousness turns from the present to the past,
the experience that is worth keeping is sorted and stored in a space–
time coordinate. The hippocampus is the machine capable of this task.
Once an immediate experience arrives, the hippocampus functions as a
librarian and also as an archivist, who catalogues and stores the informa-
tion, creating declarative memories that make up most of our biograph-
ical self — and the identity of who we are.