In a larger sense, social cognition is an extreme example of a broader issue in biology of mind, and that is social interaction in general. Even here we are beginning to make some rather remarkable progress. Cori Bargmann, a geneticist at the Rockefeller University, has studied two variants of a worm called C elegans, that differ in their feeding pattern. One variant is solitary and seeks its food alone; the other is social and forages in groups. The only difference between the two is one amino acid in an otherwise shared receptor protein. If you move the receptor from a social worm to a solitary worm, it makes the solitary worm social.
A NEUROSCIENCE SAMPLING [3.5.07]
In keeping with the theme of this year's Question: "What Are You Optimistic About", Edge asked neuroscientist and Nobel Laureate Eric Kandel for a sampling of recent developments in neuroscience that inspire his optimism. "in a field as broad and as deep as neuroscience," he writes, "it is difficult to select simply four contributions. I therefore consider this a sampling of the contributions that drive my optimism rather than a true selection of the top four. Moreover, I have simplified the task by dividing the field into four areas: Molecular Neuroscience, Systems Neuroscience, Cognitive Neuroscience, and Neuroscience of Psychiatric Disease."
ERIC R. KANDEL is University Professor at Columbia University in the Department of Biochemistry and Molecular Biophysics and in the Department of Psychiatry at Columbia and a Senior Investigator at the Howard Hughes Medical Institute. He is the recipient of the Nobel Prize in Physiology or Medicine, 2000. He is the author In Search of Memory: The Emergence of a New Science of Mind.
A NEUROSCIENCE SAMPLING
I list here four major accomplishments in neuroscience in the past year that have inspired me. I begin by saying that in a field as broad and as deep as neuroscience, it is difficult to select simply four contributions. I therefore consider this a sampling of the contributions that drive my optimism rather than a true selection of the top four. Moreover, I have simplified the task by dividing the field into four areas: Molecular Neuroscience, Systems Neuroscience, Cognitive Neuroscience, and Neuroscience of Psychiatric Disease.
Molecular Neuroscience. The
discovery of the double helix by Watson and Crick in 1952 gave rise to
a central dogma in molecular biology, according to which genes (encoded
in DNA) give rise to messenger RNAs which encode proteins,
the workhorses of the cell. The discovery a few years ago of microRNAs,
a class of small non-coding genetic elements that control the translation
of target messenger RNAs, highlighted a new layer of gene regulation
downstream from DNA. MicroRNAs have been described in numerous
species across the evolutionary spectrum, and there are thought to be
about 500 different microRNAs encoded in the human genome. Although
microRNAs are very short (only 21 nucleotides long), each is thought
to bind to a number of different messenger RNA targets. Thus
they may have a very profound effect on gene action in both the human
brain and in simpler experimental animals. The existence of microRNAs
has been known for several years but only recently has it become recognized
that they are particularly important in the nervous system where they
serve, among other functions, to regulate synaptic strength—the
effectiveness with which one neuron communicates with another.
Systems Neuroscience. In the late 1960s
and 1970s, David Hubel and Torsten Wiesel gave us the initial insight
as to how the early input stages of the cerebral cortex process and transform
the incoming visual messages. This gave us our first insight of how an
image—say, an image of a face or a landscape—is first deconstructed
and then reconstructed in the brain. In all living creatures, from simple
animals to people, knowledge of space is central to behavior. We live
in space, we move through it, we explore it, and we defend it. Space
is not only important but it is fascinating because unlike other sense
modalities, it is not analyzed by special sensory organs like the eye
for seeing or the ear for hearing. This has raised the question, How
is space represented in the brain? Immanuel Kant, the great German idealist
philosopher argued that the ability to represent space is built into
the mind. He argued that people are born with principles of ordering
space and time. These are part of what he called the categorical imperatives.
When other sensations are elicited such as visual sensations of objects,
or auditory sensations of melodies, or touch experiences, they are interwoven
automatically in specific ways with space and time. We remember people
and events in a spatial context. Because we do not have a special organ
dedicated to space, the representation of space is the cognitive sensibility
par excellence. It is the binding problem write large. The brain
must combine inputs from several different sensory modalities and then
generate a complete internal representation that does not depend exclusively
on one input. The brain commonly represents information about space in
many areas in many different ways and the properties of each representation
vary according to purpose.
When you and I talk to one another, we not only know the contents of
our own mind but we also have a sense of the content of what the other
person is thinking and how they are reacting. We have, so to speak,
a sense of the social expectations of the situation and the kinds of
ideas that the conversation brings forth in the colleague with whom
we are communicating. During the past year several important studies
have localized aspects of this function in the cerebral cortex. First,
Rebecca Saxe has found that there is a specific area in the brain at
the junction between the temporal and parietal lobes that encodes aspects
of the theory of mind. It becomes active when a person entertains ideas
about another person’s possible
responses to our actions. This new finding extends a series of important
findings from Rizzolatti’s group in Italy which first showed that
there are certain cells in the premotor areas of parietal cortex of the
monkey that respond not only when a monkey picks up a peanut but also
when the monkey sees another monkey or a human being pick up a peanut.
These cells are called mirror cells because they respond not only to
personal action but in an imitative way to the action of others. In addition
to showing a cellular basis for a theory of mind, these cells also illustrate
that the motor systems have cognitive function. Imaging experiments by
Ramachandran have shown that this area is present in people, and
that it appears to be disturbed in patients with autism.
Neuroscience of Psychiatric Disease. A major source of optimism is the emergence of an empirical, evidence-based psychotherapy. There are now a number of excellent studies that show that mild to moderately severe depression, as well as fear-based anxiety disorders and obsessive-compulsive disorders, respond to different versions of psychotherapy that are designed to focus not on deep underlying conflict but on the management of specific symptoms. The best established of these is cognitive behavioral therapy, first introduced in the 1970s by Aaron Beck at the University of Pennsylvania.
In the late 1950s, when Beck began his investigations, depressive illness
was commonly viewed as a form of introjected anger. Freud had argued
that depressed patients feel hostile and angry toward someone they love.
Because patients cannot deal with negative feelings about someone who
is important, needed, and valued, they handle those feelings by repressing
them and unconsciously directing them against themselves. It is this
self-directed anger and hatred that leads to low self-esteem and feelings