Hypnosis, Memory and the Brain
Hypnosis is a technique used by scientists to study psychological phenomena. An example is a technique known as posthypnotic amnesia (PHA). This models disorders like functional amnesia (sudden memory loss due to psychological trauma). PHA is produced by suggesting to someone hypnotized that he will forget certain things until "cancellation" (i.e. "Now you can remember everything"). PHA usually happens only when specifically suggested. It is much more likely to happen to a person with high levels of hypnotic ability. A new study shows that the hypnotic state influences brain activity related to memory.
Highly hypnotizable people with PHA usually show difficulty recalling whatever is suggested. They also show dissociation between explicit and implicit memory; even though the can't pinpoint the forgotten information it influences them. This is reversible, when the suggestion is cancelled their memories return to them. Dissociation and reversibility show the PHA in not the result of poor encoding of memory or normal forgetting. This is because as soon as the PHA is cancelled the memories return. PHA just makes the person unable to retrieve safely stored information. This is why PHA is useful for research.
Scientists use PHA to model functional amnesia because the conditions share similar features. Reports of functional amnesia show that people who are unable to remember certain things of the past still show evidence of the forgotten. As suddenly as these memories were forgotten they can be recovered.
Neuroscientist Avi Mendelsohn and colleagues at the Weizman Institute identified the brain activity petterns realting to PHA using functional magnetic resonance imaging (fMRI). They selected 25 participants, of which half were PHA responsive (PHA group), while the other half was not (non-PHA group). The participants watched a 45-minute movie. One week later the participants were hypnotized, while in the fMRI scanner, to forget the movie until a certain cue came about as the cancellation.
After hypnosis the participants were tested twice, once while hypnotized and once again after the cue to remember had been given (the exact same test both times). They were asked 40 questions specifically about the movie and 20 questions about their surroundings while watching the movie (all yes or no answered questions).
In Test 1 Mendelsohn and colleagues found that the PHA group forgot more about the movie than the non-PHA group. The PHA group had no problem with the questions about their surroundings during the movie, though they struggles with the movie questions. In Test 2, after the remembrance cue was given, both groups remembered the same amount of details. Somewhat surprisingly though, the suggestion to forget was selective in impact.
The findings of Mendelsohn's fMRIs of the participants was that; when the non-PHA group answered the questions the fMRI showed high levels of activity in places responsible for visual and verbal sequences. In the PHA group there was little or no activity in these regions while other areas were more active than usual, as to heighten the senses of the other regions.
For participants in the PHA group, brain activity in the fMRI correlated with forgetting. We can rule out the possibility of reduced activity regardless or remembrance or forgetting. This is because the PHA group showed the reduction only when the answered incorrectly; when they answered successfully though, they nearly matched the non-PHA group.
Hypnotic effects are real! Mendelsohn's study shows that hypnotic suggestions influence brain activity as well as behavior and experience. This has been shown earlier by psychologist David Oakley, who compared the brain activity of people simply asked to fake hypnosis and paralysis, and genuinely hypnotized people with suggestions for leg paralysis.
Mendelsohn's study is also important because begins to specify the underlying brain processes, which are guessed to be shared by PHA and functional amnesia. The effects of PHA shows a dampening in brain activity due to heightened activity in the prefrontal cortex.
Memories are an interwoven web of "what," "how," "where," and "when," thus the distinction between content and context could quite possibly be blurred. In this study, movie content but not movie context wasinfluenced byPHA. To make such small distinctions, the suppressor module of the brain needs to process information at quite a high level. thi module needs to act quickly;preconciously subdueing activation of information before it enters awareness. Brain imaging superior to fMRI might help clear up the paradox of suave, but quick, activity.
Whereas some forgetfulness is seen as conscious and using effort, other forgetting is automatic, effortless, and unconscious. After mapping the usual features of PHA and functional amnesia, we need to discover and compare their common processes in much greater detail.
When we incorporate the dissociation of implicit and explicit memory the neural underpinnings of PHA will become even more clear. In PHA the person cannot explicitly recall certain information, though we can see evidence of this on implicit measures. Recognition in a sense is both explicit and implicit memory. Scientists would liek to compare scans of the PHA group trying to remember the movie, with the non-PHA group. This would be challenging, but would contribute much more to complete the picture of processes in the interesting forms of forgetting.
My Response:
Though I have heard and been fascinated by hypnosis I have never really looked into it enough to see the complexity of it. This article shows that there are a great many processes and variations of what can, and cannot be done with hypnosis. This article shows mainly one type of hypnosis, but has enough information to be much longer. The possibility of controlling someone's forgetfulness about a good, or bad, memory seems alien to me. There would be many possible good uses if we could totally work this out. We could help peopl forget instances of great trauma such as a car accident, or the death of a loved one etc. This atricle really started me thinking of all the possibilities to come of hypnotism. The future looks bright!
http://www.sciam.com/article.cfm?id=hypnosis-memory-brain
Highly hypnotizable people with PHA usually show difficulty recalling whatever is suggested. They also show dissociation between explicit and implicit memory; even though the can't pinpoint the forgotten information it influences them. This is reversible, when the suggestion is cancelled their memories return to them. Dissociation and reversibility show the PHA in not the result of poor encoding of memory or normal forgetting. This is because as soon as the PHA is cancelled the memories return. PHA just makes the person unable to retrieve safely stored information. This is why PHA is useful for research.
Scientists use PHA to model functional amnesia because the conditions share similar features. Reports of functional amnesia show that people who are unable to remember certain things of the past still show evidence of the forgotten. As suddenly as these memories were forgotten they can be recovered.
Neuroscientist Avi Mendelsohn and colleagues at the Weizman Institute identified the brain activity petterns realting to PHA using functional magnetic resonance imaging (fMRI). They selected 25 participants, of which half were PHA responsive (PHA group), while the other half was not (non-PHA group). The participants watched a 45-minute movie. One week later the participants were hypnotized, while in the fMRI scanner, to forget the movie until a certain cue came about as the cancellation.
After hypnosis the participants were tested twice, once while hypnotized and once again after the cue to remember had been given (the exact same test both times). They were asked 40 questions specifically about the movie and 20 questions about their surroundings while watching the movie (all yes or no answered questions).
In Test 1 Mendelsohn and colleagues found that the PHA group forgot more about the movie than the non-PHA group. The PHA group had no problem with the questions about their surroundings during the movie, though they struggles with the movie questions. In Test 2, after the remembrance cue was given, both groups remembered the same amount of details. Somewhat surprisingly though, the suggestion to forget was selective in impact.
The findings of Mendelsohn's fMRIs of the participants was that; when the non-PHA group answered the questions the fMRI showed high levels of activity in places responsible for visual and verbal sequences. In the PHA group there was little or no activity in these regions while other areas were more active than usual, as to heighten the senses of the other regions.
For participants in the PHA group, brain activity in the fMRI correlated with forgetting. We can rule out the possibility of reduced activity regardless or remembrance or forgetting. This is because the PHA group showed the reduction only when the answered incorrectly; when they answered successfully though, they nearly matched the non-PHA group.
Hypnotic effects are real! Mendelsohn's study shows that hypnotic suggestions influence brain activity as well as behavior and experience. This has been shown earlier by psychologist David Oakley, who compared the brain activity of people simply asked to fake hypnosis and paralysis, and genuinely hypnotized people with suggestions for leg paralysis.
Mendelsohn's study is also important because begins to specify the underlying brain processes, which are guessed to be shared by PHA and functional amnesia. The effects of PHA shows a dampening in brain activity due to heightened activity in the prefrontal cortex.
Memories are an interwoven web of "what," "how," "where," and "when," thus the distinction between content and context could quite possibly be blurred. In this study, movie content but not movie context wasinfluenced byPHA. To make such small distinctions, the suppressor module of the brain needs to process information at quite a high level. thi module needs to act quickly;preconciously subdueing activation of information before it enters awareness. Brain imaging superior to fMRI might help clear up the paradox of suave, but quick, activity.
Whereas some forgetfulness is seen as conscious and using effort, other forgetting is automatic, effortless, and unconscious. After mapping the usual features of PHA and functional amnesia, we need to discover and compare their common processes in much greater detail.
When we incorporate the dissociation of implicit and explicit memory the neural underpinnings of PHA will become even more clear. In PHA the person cannot explicitly recall certain information, though we can see evidence of this on implicit measures. Recognition in a sense is both explicit and implicit memory. Scientists would liek to compare scans of the PHA group trying to remember the movie, with the non-PHA group. This would be challenging, but would contribute much more to complete the picture of processes in the interesting forms of forgetting.
My Response:
Though I have heard and been fascinated by hypnosis I have never really looked into it enough to see the complexity of it. This article shows that there are a great many processes and variations of what can, and cannot be done with hypnosis. This article shows mainly one type of hypnosis, but has enough information to be much longer. The possibility of controlling someone's forgetfulness about a good, or bad, memory seems alien to me. There would be many possible good uses if we could totally work this out. We could help peopl forget instances of great trauma such as a car accident, or the death of a loved one etc. This atricle really started me thinking of all the possibilities to come of hypnotism. The future looks bright!
http://www.sciam.com/article.cfm?id=hypnosis-memory-brain
posted by Todd T @ 4:32 PM
2 Comments:
I have to agree with Todd on how interesting hypnosis is, but I too had no idea on how complex it really is. I originally thought it was a person put someone out and then brought them back to reality when necessary, and that was it, but this article has allowed me to see it goes much deeper than that. The only thing I'm afraid of is that while it can be very good in the right hands, who knows what kind of damage could be done if an evil person learns how to hyptotize, especially on a large scale. I hope it never gets to that point!
I never realized how complicated hypnosis really was. The whole idea of having more than one type of hypnosis methods such as PHA is very fascinating. It gets me to thinking of other possibilities the human mind is capable of. I myself know a couple people who have expeirienced hypnosis. My Uncle had a quite plesant expeirience and was able to quit smoking after just one session. But like Krista said it is dangerous in the hands of evil. I also know someone who was put under hypnosis but instead of taking memory out the hypnotist added dark and damaging memories of my aquatince's parents. From this day on she still has trouble trusting them, but like the article said she is begining to tap into her former memories and recover.
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