It's all neurons and connections. Despite decades
of highly sophisticated analyses of anatomy, physiology, and molecular
biology, it is still jarring to realize that our own behavior
results from the patterns of stimulation that arrive at nerve
cells, from the transformations to these patterns that occur within
and between nerve cells, and from the patterns of activation they
send to muscles and elsewhere. This essential way in which we
are a product of our biology applies not only to disease and injury
but also to the focus of this course: the links between memory
and creativity.
What insights, then, does neurobiology give into
memory and creativity: attributes that make us human and make
us individual? First is the discovery that use strengthens neural
connections (synapses) and disuse weakens them. At any age, decreasing
social and cognitive stimulation for a laboratory rat results
in massive loss of synapses between nerve cells; restoring the
stimulation results in regrowth. The principle applies to us,
too: we have the ability to affect our own biology.
Second, there are brain areas that are essential
for making new memories. For example, if the hippocampus is injured,
old memories remain and many other functions are intact. But no
new conscious memories are added. Such a person gradually loses
contact with the world. He or she is locked at the moment of the
loss and the world moves on. The principle: each of us must always
be updating and amending memory and joining what is old to what
is new, and doing so requires special brain regions.
Third, there is no single place in the brain at which
memories are stored, and which would provide us with a perfect
record of the past if we could just get to it. Rather, memories
appear to be stored as enhanced perceptions of memory components,
and enhanced neural links between the areas that retain these
components together with links that tie in time, place, circumstances,
emotions and sensory perceptions. This means that visual components
of memories are stored as enhanced connections in regions of cortex
that were directly activated by seeing and interpreting what was
seen. It means that actions of past experience on brain structure
can affect future perception. In turn, it means that making new
memories can modify older ones if older components are activated
together with novel associations. Since similar memories overlap,
common features are strengthened and others may be lost - most
of us remember relatively few details of fall days of years past
but know much of what fall is like. The principle: there is no
secure memory archive in the brain but instead an amazingly flexible
system for making a memory of anything that can be experienced
and melding it with past and future experiences.
My own research is on singing in songbirds and the
brain regions responsible for learning, remembering and expressing
song. Two recent findings in my laboratory illumine the processes
that occur in the brains of birds and how the memory principles
described above may eventually be augmented. First, brain areas
related to song have many more synapses in baby birds before they
have learned song than they do afterward. Graduate student Christine
Collins and post-doc Elisabeth Wallhausser have found that the
extra synapses stay on in zebra finches that are kept from hearing
and learning a song. Perhaps the baby bird builds a neural system
that could be used to produce any possible song of its species.
Then, when it hears the song of its father, it strengthens the
paths used to remember that song and erases the others. Such a
learning system would be fast, accurate and long-lasting, but
would be limited in the forms of learning that are possible. For
a finch that wants to grow up and sound like a finch, such limitations
are good. These findings suggest that our understanding of our
own memory must also include constraints: there may be memories
that we cannot make because we don't have or can't build the connections
that would be needed to encode them.
Second, birds often practice many sounds while young
and then settle on a small number to produce in the song throughout
adult life. Graduate student Stacey Benton damaged one of the
brain areas involved in song perception in adult sparrows. Several
of the birds then began to sing a song in which some of the sounds
that had been practiced and discarded as a juvenile two years
earlier were now included as part of the song. Apparently, old
memories may still be present in the brain, even if they are not
expressed. Could they still affect the bird's judgment about the
songs of other birds? Could there be memories in us that, though
inhibited for large parts of our lives, still affect our behavior?
The findings described above can affect how we understand
the intertwining of memory and creativity in ourselves. They suggest
that perception and imagination and memory are physically linked
- they activate and alter overlapping neural structures and, through
physical processes, one can enhance the substrate for the others.
They show that there are constraints in what we perceive and in
what we can learn. But in ourselves as in the birds, the constraints
can give structure and fidelity to our learning. They indicate
that memories build on and modify prior neural structure. While
this process comes with the cost of losing detail, it leads to
an understanding of typicality and of essence that are key to
creativity. Finally, memory storage is distributed with links
between components. It is common for us to say that one experience
or domain of knowledge is like another, perhaps reflecting our
internal observation that the two domains share neural links in
common. Perhaps creativity flows from pushing such parallels and
discovering that two such domains also share further less obvious
links. This can lead to experiments such as studying whether song
learning in birds and language learning in humans have deep similarities
in development and mechanism. It can also lead to new ways of
looking at other domains of knowledge: what was my father's song?
Which parts do I now sing and where have I improvised in what
I pass on to my children?
Timothy DeVoogd (psychology), has taught courses on the neurobiology of learning and memory since 1982. He studies the neurobiology of brain areas involved in song learning in birds. In recent research, he has compared these brain areas between bird species that learn different amounts, giving new insights into the evolution of learning - and giving a good excuse for international travel and collaboration.
This article is Copyright © 1996 Timothy DeVoogd. All Rights Reserved.