On 18 Aug 2006 11:59:45 -0700, nospam8 at rogers.com wrote:
>thanks for your reply.
>>I wonder if there is any research into applying nanotechnology to
>reduce the invasiveness of this procedure, and potentially record a
>group of neurons at the same time
Yes, there are techniques to record from multiple cells.
Extracellular electrodes pick up activity from a group of nearby
cells. Google "multicell recording". The invasiveness of the
technique stems from the fact that the electrodes must be extremely
close to the cells -- micrometers or tens of micrometers and the
electrode plus its mechanical extension and leads, needed to insert it
and record, must pass through all the intervening brain tissue causing
damage all along the track. There are techniques for producing an
microarray of electrodes (google "array recording") but again, these
only record from neurons extremely close to or touching the electrode
array. The technique is extremely useful for recording from brain
slices or cultured neurons, not from whole brains.
There are other difficulties recording from neurons that are still
firmly embedded inside large brains. These single cell techniques
require that the electrode be solidly and firmly located. Any
jiggling or vibration of even a small number of micrometers makes the
recording virtually useless. The pulsating blood pressure jiggles the
brain more than that and any mechanical vibration in the electrode
system is disastrous. Even with these problems it is possible to
implant electrodes in the brain and allow the animal to recover from
surgery and so record activity from the freely moving animal. See
for some examples.