Physics (Internal)
Time and space in the mind and brain
This event is part of the Biophysics/Condensed Matter Seminar Series.
Abstract: Cognitive states appear to be in one-to-one correspondence
with states of the brain. In principle it should be possible to
develop satisfactory physical models of our internal experience. The
approach we take is to first develop concise mathematical descriptions
that account for a broad variety of observable behavioral phenomena.
If these descriptions are correct, then they ought to be constrained
by neural observations as well as behavioral ones.
Much of memory research hinges on how people remember recent events.
I describe how the real-time stimulus function leading up to the
present moment can be encoded via the Laplace transform. A
real-domain method for approximating the inversion of the Laplace
transform results in a scale-invariant representation of recent
history as a function of internal past time. A translation operator
can be specified that enables the prediction of trajectories of future
states forward in internal future time. The model provides a concise
description of a variety of behavioral results in episodic memory,
interval timing, and conditioning. At the neural level, development
of the model paralleled the observation of time cells'' in the<br />rodent hippocampus, a brain structure that is essential for episodic<br />memory. The hippocampus is also believed to be important for our<br />sense of allocentric space: hippocampalplace cells'' show
sensitivity to a variety of spatial correlates as the animal moves
around its environment. I show that the equations of the model of
internal time can be seen as a special case of a more general
framework that describes not only time cells but also a wide variety
of place cell phenomena as well.