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Opinion,
Comment & Reviews
Reproductive technologies |
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Memory
research and 'designer babies'
By Stuart Derbyshire
The news this week that US scientists may have used genetics
to improve the memory of mice led to the predicatble warnings
of 'the horrifying creation of designer babies' with massive
IQs' (Daily Mail, 2/9/99). Spokeswoman for Life Nuala Scarisbrick
unsurprisingly called the research 'an insult to humanity'.
More worryingly, Dr Vivienne Nathanson, head of ethics at
the BMA also reportedly responded is similarly alarmist terms:
'Society is learning to celebrate people for their individuality,
not just because they are particularly bright. This discovery
leads to the spectre of designer bbabies and the concept of
children being rejected because they do not have these qualities.'
But does the new research warrant such a response? In this
commentary, Dr Stuart Derbyshire argues it is nonsense to
talk of an 'intelligence gene'.
Teams of researchers from Princeton University, New Jersey,
and another from the University of Tokyo have discovered improved
memory and learning ability in two strains of genetically
modified mice. The results have caused much excitement, with
some commentators talking about an 'intelligence gene' - raising
the possibility of enhancing the normal intelligence of 'other
mammals', including humans.
But while this work is undoubtedly a step towards enhancement
of some of the basic information-processing capacities that
all mammals share, it is still a long stretch from these studies
to a facilitation of human memory, let alone intelligence.
Memory in humans and all other mammals is intricately tied
in with a piece of the brain called the hippocampus. If you
were to be so unlucky as to lose your hippocampus on both
sides of your brain, you would never again be able to place
an event into long-term memory. Memories never develop beyond
the moment of hippocampal destruction and the patient forever
lives in the past and immediate present.
Knowing this important site for memory, researchers have turned
their attention towards the mechanisms of the hippocampus.
This is what the current studies investigated. It is known
that information is shuffled around and maintained inside
the hippocampus dependent upon the properties of receptors
(sites at which actions take place) and their interaction
with neurotransmitters (chemicals that allow communication
between receptor sites). The important receptor is NMDA and
the important neurotransmitter is glutamate. When NMDA binds
to glutamate a current is evoked which opens a channel allowing
calcium ions to enter the cell. This is the magical moment
when the cells of the hippocampus talk in harmony and strengthen
their connections, known technically as long-term potentiation
(LTP) and more commonly as the beginning of memory. The researchers
in Princeton hoped to improve the memory of mice through the
increase of an NMDA subtype that has an extended LTP - while
the researchers at Tokyo deleted the genetic code for a non-NMDA
hippocampal receptor that inhibits LTP, thereby inadvertently
extending overall LTP.
Both groups demonstrated improved memory in their transgenic
strains through a standard behavioural test. The mice were
released into a shallow pool of water and swam around until
stumbling across a hidden platform and standing on it. This
was done on multiple occasions and the time taken to reach
the platform was recorded. All the mice reached the platform
more quickly on later trials, indicating learning. The transgenic
mice, however, performed better than the normal mice, showing
further improved learning due to the genetic manipulation.
So will we be able to create humans with super memories? Perhaps.
I have no doubt that humans and mice share important properties
relating to the hippocampus and its basic function. But even
so, memory in mice and memory in humans are far removed. Simple
associative learning - discovering that A follows B, etc -
is an aspect of memory and, if you are a mouse surviving from
one moment to the next, it might be terrific to have your
associative learning enhanced. But humans do not survive in
this manner - we have developed ourselves and our society
and can operate on a more general, abstract level. Being able
to understand connections between A and B might be a prerequisite
for abstract memories but that does not mean a better recognition
of concrete relationships will improve abstract memory. It
might even be detrimental. Humans use memory in a transformative
manner to go beyond simple relationships and to develop abstract
connections.
The ability to draw abstract relationships and pursue meaningful
goals is the hallmark of human intelligence that is sorely
lacking in the mouse world - even in the newly created super
mouse world. In the mouse, memory is merely an extension of
their basic biological function with zero intelligent content.
Our intelligence remains under the influence of basic information-processing
skills (as evidenced by its severe compromising when processing
is lost to dementia), but intelligence is more than the simple
additive effects of processing environmental associations.
For humans, memory is not a natural extension of biology but
is a part of the transformation and interweaving of innate
biological processes into higher intelligent function.
The transformation of our biological information-processing
capacity, which we share with mice, takes place in the sociocultural
world, which we do not share with mice. During development,
formal schooling and other cultural interventions, the subordination
of biological instinct to volitional control is nurtured and
encouraged. Memory ceases to be slavishly dictated by internal
and external events and becomes a tool that can be used in
the pursuit of reasoned goals. A genetic and neural influence
can remain, but the cause of intelligence lies outside of
genetics and pharmacology.
Dr Stuart Derbyshire is head of neuro-imaging at the Neuroenteric
Disease Program, University of California in Los Angeles.
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