Freethought & Rationalism Archive

Jack the Bodiless · 03-14-2003, 11:34 AM

Quote:

The world's first brain prosthesis - an artificial hippocampus - is about to be tested in California. Unlike devices like cochlear implants, which merely stimulate brain activity, this silicon chip implant will perform the same processes as the damaged part of the brain it is replacing.

The prosthesis will first be tested on tissue from rats' brains, and then on live animals. If all goes well, it will then be tested as a way to help people who have suffered brain damage due to stroke, epilepsy or Alzheimer's disease...

...The job of the hippocampus appears to be to "encode" experiences so they can be stored as long-term memories elsewhere in the brain. "If you lose your hippocampus you only lose the ability to store new memories," says Berger. That offers a relatively simple and safe way to test the device: if someone with the prosthesis regains the ability to store new memories, then it's safe to assume it works...

...No one understands how the hippocampus encodes information. So the team simply copied its behaviour. Slices of rat hippocampus were stimulated with electrical signals, millions of times over, until they could be sure which electrical input produces a corresponding output. Putting the information from various slices together gave the team a mathematical model of the entire hippocampus.

They then programmed the model onto a chip, which in a human patient would sit on the skull rather than inside the brain. It communicates with the brain through two arrays of electrodes, placed on either side of the damaged area. One records the electrical activity coming in from the rest of the brain, while the other sends appropriate electrical instructions back out to the brain.

A thought struck me when reading this:

If memories actually pass through the hippocampus on the way to storage in long-term memory, could the pattern of electrical impulses be recorded by a modified version of this device, and played back through a similar device in somebody else's brain?

"Memory tapes", anyone?

Any brain specialists around here?

Paul2 · 03-14-2003, 11:38 AM

i wonder if it would be able to be adapted to accept an external input.... implanting memories.

Tom Sawyer · 03-14-2003, 12:22 PM

The movie Strange Days had something like this in it. The new "drug" on the street was experiencing other people's memories. Dirty old men could feel what it's like to be a teenage girl taking a shower, etc.

I've always thought that it would be really cool if something like that were possible, so I'm hoping this technology pans out to be able to do something like that.

Jesse · 03-14-2003, 01:39 PM

I doubt it. The article says that they don't really know how the hippocampus works, they just copied its large-scale behavior, so if it works at all it seems likely that the hippocampus doesn't actually record memories in a fine-grained way, it just facilitates the encoding of memories in other parts of the brain, like the cortex. On the other hand, if the hippocampus does record detailed memories, then I doubt that a prosthesis that just copies its behavior on a gross level will work at all.

-RRH- · 03-15-2003, 10:23 AM

Of course, I'm not a doctor, and I don't know a lot about neuroscience, so I'm probably missing some subtleties here, but...

Could you theoretically record someone as they are storing memories and play that back for someone else? A question I would need answering is, "Does all the information for long-term memory storage pass through the hippocampus?" If yes, then I think it would be possible, if no, then this would not be enough.

I would guess if the artificial hippocampus works, it will help quite a lot in the study of the hippocampus and how memories are formed.

Also, in Strange Days, the SQUID recorded sensory perceptions, not memories. Playing false memories through the hippocampus would be more akin to Total Recall.

Corwin · 03-17-2003, 09:49 AM

Quote:

Also, in Strange Days, the SQUID recorded sensory perceptions, not memories. Playing false memories through the hippocampus would be more akin to Total Recall.

...which could actually be amazingly useful, if you could get it to work.

The question is, could memories be recorded in any format that would be useable? Honestly I don't know. Brain function isn't purely digital, so it isn't like ripping a cd or copying a DAT... but then sound isn't digital either so it might be possible.

Insufficient data.

I suppose the bottom line is 'if they can get it to work it could be pretty damn cool.

'

Corona688 · 03-18-2003, 11:48 AM

As I understand it, the hippocampus doesn't STORE memories, as much as associates. them; like connect memories of smell, taste, and texture into something that says 'icecream'.

So a loose computer analogy would be, it's not the brain's physical storage, but more like the FAT table. And of course, a FAT table is useless without the data it maps to.

So, I don't think this device will be able to tell us precisely WHAT is stored in the brain, or how. But it could be very useful in telling us WHERE, which is the first step imho.

-RRH- · 03-18-2003, 06:59 PM

Is the prosthesis stateless?

Jack the Bodiless · 03-19-2003, 09:18 AM

Well, a FAT table stores data within itself, and I get the impression that this thing doesn't.

I'm hoping that it's more like an IDE or SCSI interface for a disk drive, which encodes data for storage as it passes through. Which would mean that you don't need to know what coding was done before or after the hippocampus: if you can intercept it and duplicate it, it should copy the data into memory.

However, it could be an interface through which "FAT" data passes en route to the FAT table only: a list of instructions on which memories (stored elsewhere) to keep, and where, but not the actual content of the memories.

Also, there might be problems even if it DOES pass memories, if it also passes storage locations. Person A might file the memory into a location which is vacant in HIS brain, but person B's brain might be storing the memory of his wife's name at that location, or how to speak English...

tribalbeeyatch · 03-19-2003, 10:57 AM

It seems very unlikely that you could "play back" hippocampal traces through another person's brain and have them experience the same things. The hippocampus isn't the only structure that is active during long-term memory formation, and so its signal alone probably wouldn't be adequate.

I really wonder if this thing is going to work at all. Given the crude electrophysiology that it sounds like they used to develop their chip, I am inclined to doubt. At the same time, though, given the remarkable plasticity of the brain, I am somewhat optimistic that the brain may be able to adapt itself such that it is able to interpret at least some of the information that the chip is encoding. Even a partial restoration of memory function would really be amazing!

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03-14-2003, 11:38 AM	#2
Paul2 Veteran Member Join Date: Sep 2002 Location: Ohio Posts: 1,088	i wonder if it would be able to be adapted to accept an external input.... implanting memories.

03-14-2003, 12:22 PM	#3
Tom Sawyer Talk Freethought Staff Join Date: Jun 2002 Location: Toronto, eh Posts: 42,293	The movie Strange Days had something like this in it. The new "drug" on the street was experiencing other people's memories. Dirty old men could feel what it's like to be a teenage girl taking a shower, etc. I've always thought that it would be really cool if something like that were possible, so I'm hoping this technology pans out to be able to do something like that.

03-14-2003, 01:39 PM	#4
Jesse Moderator - Science Discussions Join Date: Feb 2001 Location: Providence, RI, USA Posts: 9,908	I doubt it. The article says that they don't really know how the hippocampus works, they just copied its large-scale behavior, so if it works at all it seems likely that the hippocampus doesn't actually record memories in a fine-grained way, it just facilitates the encoding of memories in other parts of the brain, like the cortex. On the other hand, if the hippocampus does record detailed memories, then I doubt that a prosthesis that just copies its behavior on a gross level will work at all.

03-15-2003, 10:23 AM	#5
-RRH- Veteran Member Join Date: Nov 2001 Location: Winnipeg Posts: 2,047	Of course, I'm not a doctor, and I don't know a lot about neuroscience, so I'm probably missing some subtleties here, but... Could you theoretically record someone as they are storing memories and play that back for someone else? A question I would need answering is, "Does all the information for long-term memory storage pass through the hippocampus?" If yes, then I think it would be possible, if no, then this would not be enough. I would guess if the artificial hippocampus works, it will help quite a lot in the study of the hippocampus and how memories are formed. Also, in Strange Days, the SQUID recorded sensory perceptions, not memories. Playing false memories through the hippocampus would be more akin to Total Recall.

03-18-2003, 11:48 AM	#7
Corona688 Veteran Member Join Date: Feb 2001 Location: Hiding from Julian ;) Posts: 5,368	As I understand it, the hippocampus doesn't STORE memories, as much as associates. them; like connect memories of smell, taste, and texture into something that says 'icecream'. So a loose computer analogy would be, it's not the brain's physical storage, but more like the FAT table. And of course, a FAT table is useless without the data it maps to. So, I don't think this device will be able to tell us precisely WHAT is stored in the brain, or how. But it could be very useful in telling us WHERE, which is the first step imho.

03-18-2003, 06:59 PM	#8
-RRH- Veteran Member Join Date: Nov 2001 Location: Winnipeg Posts: 2,047	Is the prosthesis stateless?

03-19-2003, 09:18 AM	#9
Jack the Bodiless Veteran Member Join Date: Feb 2001 Location: UK Posts: 5,815	Well, a FAT table stores data within itself, and I get the impression that this thing doesn't. I'm hoping that it's more like an IDE or SCSI interface for a disk drive, which encodes data for storage as it passes through. Which would mean that you don't need to know what coding was done before or after the hippocampus: if you can intercept it and duplicate it, it should copy the data into memory. However, it could be an interface through which "FAT" data passes en route to the FAT table only: a list of instructions on which memories (stored elsewhere) to keep, and where, but not the actual content of the memories. Also, there might be problems even if it DOES pass memories, if it also passes storage locations. Person A might file the memory into a location which is vacant in HIS brain, but person B's brain might be storing the memory of his wife's name at that location, or how to speak English...

03-19-2003, 10:57 AM	#10
tribalbeeyatch Senior Member Join Date: Apr 2001 Location: On the edge Posts: 509	It seems very unlikely that you could "play back" hippocampal traces through another person's brain and have them experience the same things. The hippocampus isn't the only structure that is active during long-term memory formation, and so its signal alone probably wouldn't be adequate. I really wonder if this thing is going to work at all. Given the crude electrophysiology that it sounds like they used to develop their chip, I am inclined to doubt. At the same time, though, given the remarkable plasticity of the brain, I am somewhat optimistic that the brain may be able to adapt itself such that it is able to interpret at least some of the information that the chip is encoding. Even a partial restoration of memory function would really be amazing!

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