I do not think that this will allow you to activate photographic
memory but it also might well be able to do that. My point is that a
prosthetic device will be in demand for everyone in short order once
it proves possible.
This also strongly informs us of the ways and means to developing
brain training, which presently is also abandoned to those most in
need. The results of brain training needs to be universally applied.
This is well worth pondering.
How to Make an
Implant that Improves the Brain
Loren Frank
Enhancing the flow of
information through the brain could be crucial to making
neuroprosthetics practical.
May 9, 2013
The abilities to
learn, remember, evaluate, and decide are central to who we are and
how we live. Damage to or dysfunction of the brain circuitry that
supports these functions can be devastating, leading to Alzheimer’s,
schizophrenia, PTSD, or many other disorders. Current treatments,
which are drug-based or behavioral, have limited efficacy in treating
these problems. There is a pressing need for something more
effective.
One promising
approach is to build an interactive device to help the brain learn,
remember, evaluate, and decide. One might, for example, construct
a system that would identify patterns of brain activity tied to
particular experiences and then, when called upon, impose those
patterns on the brain. Ted Berger, Sam Deadwyler, Robert Hampsom, and
colleagues have used this approach (see “Memory Implants”). They
are able to identify and then impose, via electrical stimulation,
specific patterns of brain activity that improve a rat’s
performance in a memory task. They have also shown that in monkeys
stimulation can help the animal perform a task where it must remember
a particular item.
Their ability to
improve performance is impressive. However, there are fundamental
limitations to an approach where the desired neural pattern must be
known and then imposed. The animals used in their studies were
trained to do a single task for weeks or months and the stimulation
was customized to produce the right outcome for that task. This is
only feasible for a few well-learned experiences in a predictable and
constrained environment.
New and complex
experiences engage large numbers of neurons scattered across multiple
brain regions. These individual neurons are physically adjacent to
other neurons that contribute to other memories, so selectively
stimulating the right neurons is difficult if not impossible. And to
make matters even more challenging, the set of neurons involved in
storing a particular memory can evolve as that memory is processed in
the brain. As a result, imposing the right patterns for all desired
experiences, both past and future, requires technology far beyond
what is possible today.
I believe the
answer to be an alternative approach based on enhancing flows of
information through the brain. The importance of information flow can
be appreciated when we consider how the brain makes and uses
memories. During learning, information from the outside world drives
brain activity and changes in the connections between neurons. This
occurs most prominently in the hippocampus, a brain structure
critical for laying down memories for the events of daily life. Thus,
during learning, external information must flow to the hippocampus if
memories are to be stored.
Once information has
been stored in the hippocampus, a different flow of information is
required to create a long-lasting memory. During periods of rest
and sleep, the hippocampus “reactivates” stored memories, driving
activity throughout the rest of the brain. Current theories suggest
that the hippocampus acts like a teacher, repeatedly sending out what
it has learned to the rest of the brain to help engrain memories in
more stable and distributed brain networks. This “consolidation”
process depends on the flow of internal information from the
hippocampus to the rest of the brain.
Finally, when a memory
is retrieved a similar pattern of internally driven flow is required.
For many memories, the hippocampus is required for memory retrieval,
and once again hippocampal activity drives the reinstatement of the
memory pattern throughout the brain. This process depends on the same
hippocampal reactivation events that contribute to memory
consolidation.
Different flows
of information can be engaged at different intensities as well.
Some memories stay with us and guide our choices for a lifetime,
while others fade with time. We and others have shown that new
and rewarded experiences drive both profound changes in brain
activity, and strong memory reactivation. Familiar and
unrewarded experiences drive smaller changes and weaker reactivation.
Further, we have recently shown that the intensity of memory
reactivation in the hippocampus, measured as the number of neurons
active together during each reactivation event, can predict whether
an the next decision an animal makes is going to be right or wrong.
Our findings suggest that when the animal reactivates effectively, it
does a better job of considering possible future options (based on
past experiences) and then makes better choices.
These results point to
an alternative approach to helping the brain learn, remember and
decide more effectively. Instead of imposing a specific pattern for
each experience, we could enhance the flow of information to the
hippocampus during learning and the intensity of memory reactivation
from the hippocampus during memory consolidation and retrieval. We
are able to detect signatures of different flows of information
associated with learning and remembering. We are also beginning to
understand the circuits that control this flow, which include
neuromodulatory regions that are often damaged in disease states.
Importantly, these modulatory circuits are more localized and easier
to manipulate than the distributed populations of neurons in the
hippocampus and elsewhere that are activated for each specific
experience.
Thus, an effective
cognitive neuroprosthetic would detect what the brain is trying to do
(learn, consolidate or retrieve) and then amplify activity in the
relevant control circuits to enhance the essential flows of
information. We know that even in diseases like Alzheimer’s
where there is substantial damage to the brain, patients have good
days and bad days. On good days the brain smoothly transitions among
distinct functions, each associated with a particular flow of
information. On bad days these functions may become less distinct and
the flows of information muddled. Our goal then, would be to restore
the flows of information underlying different mental functions.
A prosthetic device
has the potential to adapt to the moment-by-moment changes in
information flow necessary for different types of mental processing.
By contrast, drugs that seek to treat cognitive dysfunction may
effectively amplify one type of processing but cannot adapt to the
dynamic requirements of mental function. Thus, constructing a device
that makes the brain’s control circuits work more effectively
offers a powerful approach to treating disease and maximizing mental
capacity.
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