Brain info is high-density

Robin Hanson (
Fri, 01 Oct 1999 13:07:53 -0400

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>Date: Fri, 1 Oct 1999 17:38:43 +0100
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>Subject: [evol-psych] New research method reveals high-density information
>storage in the brain
>New research method reveals high-density information storage in the brain
>Using a new method of infrared-guided laser stimulation, researchers at
>the Max
>Planck Institute of Psychiatry in Munich/Germany have discovered that
>information can be stored in the brain with very high spatial density on the
>surface of every single neuron (Science 1 October 1999).
>The new method was developed by Hans-Ulrich Dodt from the Max Planck Institute
>of Psychiatry. In the past, he had developed a method to visualize nerve cells
>in the depth of small pieces of rat brain. To achieve this, Dodt used a
>microscope and infrared light instead of normal light. In his new method,
>so-called "infrared-guided laser stimulation", he coupled now a highly precise
>UV-laser with his infrared microscope aiming with the laser beam at neurons to
>be investigated. The method allows the stimulation of selected target
>points on
>single neurons with a spatial precision of 10 m m.
>A solution was added to the brain slices which contained neurotransmitter in a
>special chemical form, which becomes only active if the so called 'caged
>neurotransmitter' is illuminated by the UV-laser. Then, the neurotransmitter
>was set free from its 'cage' at the point at which the laser aims. Thus,
>it has
>become possible for scientists to do the same in the laboratory what a synapse
>does in the brain, but now exactly at the point and time when the scientist
>wants it. As this is something that neuroscientists all over the world always
>wanted, the method of "infrared-guided laser stimulation" will probably be
>quickly taken up by many other laboratories.
>A research team at the Max Planck Institute for Psychiatry applied the new
>method to investigate the so-called "long-term depression" (LTD), a very
>important molecular mechanism in the brain. Actually, mechanisms like
>depression and long-term potentiation (LTP) are regarded by many
>researchers as
>the basis for memory formation in the brain. It has been controversially
>debated how precise the underlying modifications of the neuronal membrane can
>be and where these modifications take place. The Max Planck researchers have
>discovered that these modifications are spatially highly restricted. Thus,
>information can probably be stored with very high density on the surface of
>neurons. During the experiments, it became apparent that a modification of the
>"receptor", the postsynaptic neuron, is all what is needed to understand the
>mechanism of long-term potentiation. Therefore, modifications of the amount of
>neurotransmitter that is released during LTD can be neglected.
>As the UV-laser stimulation allowed the release of the neurotransmitter
>glutamate from an inactive form of caged glutamate in a very small region on
>the neuron, the researchers could investigate how big the region on the neuron
>was that experienced LTD. They found that this region was not bigger than the
>resolution of their method, i.e. only a few Micrometer. Thus, even single
>synapses may undergo long-term depression and each single synapse could be
>to store information separately from its neighbour. One could compare this
>possibility for information storage in the brain with the "high densitiy
>information storage" on a CD-ROM.
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>The Descent of Mind

Robin Hanson Asst. Prof. Economics, George Mason University MSN 1D3, Carow Hall, Fairfax VA 22030
703-993-2326 FAX: 703-993-2323