The Physiological Basis of Memory
Sleep is another important factor for memory storage. During sleep, the hippocampus and neocortex take part in a carefully choreographed dialogue in which the hippocampus replays recent events: the same hippocampal neurons active during an experience become activated again during slow-wave sleep, over and over in a time-compressed manner, helping to update the neocortex as to what needs to be stored.
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Site search Search. Site search Search Menu. How are memories formed? Different 'neuron ensembles' for different memories Memories occur when specific groups of neurons are reactivated. Memories are stored by changing the connections between neurons. A five-year-old child will activate a certain group of neurons Ensemble A ; whereas adults will activate a different ensemble Ensemble A' with the same stimulus. Synaptic plasticity driven by repeated experience can change the connection strengths between neurons. A chapter on the role of catecholamines in memory processing concludes the book.
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Learning and memory under stress: implications for the classroom
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Institutional Subscription. Free Shipping Free global shipping No minimum order. Sometimes this fixation results in a kind of "flashbulb" effect. In critical incidents a Flashbulb memory is often seen when an initial image or aspect of the critical incident will be all that is remembered.
Physiology of Learning and Memory : Hertie-Institut für klinische Hirnforschung
This is similar to the process that would occur if you were moving down a familiar hallway or street, saw something new, and thought intently about that new stimulus as you continued to walk. At the end of the walk it is likely that you would have a vivid memory of this one new stimulus, but could not remember anything else that you saw or did, even though you looked at and moved around things in your path. Most of us have experienced something similar many times. In critical incidents this common process can be greatly amplified by the surprise and intensity of the initial shock.
The individual essentially functions on autopilot during the critical incident, while the mind continues to dwell on and try to make sense out of that initial image. Immediately afterwards, that image may be all that is remembered. In addition to the failure to attend which results from fixation and sensory overload, there is a body of research which indicates that intense stress will result in a failure to recall anything learned in a situation Duncan, ; Squire McGaugh and Khalsa indicate that this effect is due to the flood of stress hormones in the brain which occurs during intense trauma.
The combination of these factors will very often result in "post-incident amnesia" in which, immediately after a critical incident, the majority of information will not be remembered. This can explain, for example, the common process by which most mothers tend not to remember the intense pain of childbirth, and are subsequently willing to have more children.
The greater the trauma, the greater the impact of post-incident amnesia is likely to be. Key factors which will increase the stress include: the perception of threat or danger, the suddenness of the threat and the available time to respond or prepare, the amount of sensory input needing to be processed, and the degree of physical effort aerobic and anaerobic output that was engaged in during the incident.
If the individual is physically wounded or injured the effect will be even greater, and the effects of post-incident amnesia will be greatest if the wound or injury results in unconsciousness. Based on extensive combat experience, the U. Army has a common understanding that, "The first report is never right. Furthermore, combat leaders throughout history have understood that it will be extraordinarily difficult to make sense out of a battle until the day after combat, when the troops have had a night's sleep, since information gathered from "shell shocked" soldiers immediately after combat is notoriously poor.
After a critical incident, much of the information may still be in the brain, but it has not been processed in such a manner that it can be retrieved. But one of the key factors in being able to retrieve this information appears to be sleep. In particular, it appears that REM sleep helps consolidate unusual information that requires a good deal of adaptation in order for it to be absorbed Pearlman, Research indicates that during sleep the brain divides new information into "wanted' and "unwanted" categories, and makes new associations in light of the day's experiences.
Thus, it can be observed that, immediately after experiencing a critical incident, individuals have not had an opportunity to mentally process and refine what they have experienced. But, after a night's sleep there should b esignificant memory recovery. If an individual has been kept isolated from other sources of information, the memories at this point approximately 24 hours after the incident should be the most "pure" since they have not yet integrated data from other sources.
data.flinttworks.kayak.rocks/map307.php It should be noted, however, that if the initial night's sleep has been disturbed, then the memory recovery which should occur as a result of sleep will be potentially disrupted. If the trauma encountered in the critical incident resulted in unconsciousness, or an operation requiring general anesthesia, then there is a good possibility that normal memory recovery will be greatly disrupted.
The ability for an officer to convict the guilty and defend the innocent in a court of law, or even to defend himself against spurious charges, is greatly influenced by understanding the memory recovery process and by safeguarding this first night's sleep. If a group debriefing is conducted 24 hours after an incident preferably after an individual debrief , then the exchange of information within the group will serve as legitimate memory cues which will greatly aid in memory retrieval.
Most of this memory reconstruction will be legitimate, but from this point on and particularly after another night's sleep in which the group debrief is process into memory during REM sleep there is a slight but increasingly significant danger of memory contamination. The desire for the brain to seek patterns and sense out of chaos is powerful, fundamental, and basic to human nature.
Hobson states that the brain "is so inexorably bent upon the quest for meaning that it attributes and even creates meaning when there is little or none to be found in the data. Contamination occurs when information outside actual experience is integrated into the reconstruction of memory.
The implications of critical incident amnesia on law enforcement are profound, and it is vital that procedures be established which will ensure that the most accurate and most complete memories are protected and preserved as a part of standard procedures. The following procedures are recommended:. Educate all officers on the effects of stress on memory, in order to ensure that they understand and apply the procedures outlined below. This education process is also vital to reduce guilt and confusion over memory loss, and to reduce the potential for post-traumatic stress disorder.
Administrators, internal affairs personnel and prosecutors should also be educated so that all individuals are working together to ensure that the most accurate possible information is being retained. An initial post-incident interview or debriefing, or report should be conducted as soon as reasonably possible after a critical incident.
This should be a quick narrative review of what occurred, and it should be remembered that it is very likely a subject officer, victim, or bystander will not remember the majority of events that occurred in the incident. Type of weapon handgun, knife but not the characteristics of the weapon. General information about the suspect.
General details about the encounter. These interviews should probably be tape recorded and transcribed, since the residual sympathetic nervous system effects on fine motor control will often make hand written reports illegible. Of course, during this and all other interviews, the interviewers should make a conscious effort not to contaminate the process by suggesting ideas about the crime or the suspect to any witnesses. The interviews should be conducted on an individual basis, and reasonable efforts should be made to ensure that the subject is isolated from other sources of information such as news reports or other witnesses until the next interview, which will take place after a good night's sleep.
Every effort should be made to ensure that the subject receives a healthy night's sleep after the incident. Drugs which are administered to the subject sleeping pills, anesthesia, etc. After the first sleep period generally 24 hours later the subject should be interviewed again, and the subject can be expected to remember the majority of the details regarding the incident and to refine many of the fine points. In the case of law enforcement officers a written report at this time may be appropriate, and it should be understood that the officer may add significantly to his or her earlier statements.
A group interview or group debriefing should then be conducted as soon as reasonably possible after completion of the second set of individual interviews. The memories related in the second interview may be the most pure, but the subject will almost certainly not recover all available memory of the incident until exposed to the retrieval cues that can be provided by other witnesses. It is important that the subject get a chance to formally complete this process in an environment in which each individual is required to completely relate their experiences and observations.
Very often this environment will create comments such as, "So that's what that was, I saw that too! This kind of group debriefing was pioneered by Brigadier General S. Marshall in WWII where it was found to be extraordinarily effective at achieving a complete picture of what occurred in combat situations Marshall, Recently the U. Army has created Combat Stress Teams which are assigned at brigade level in every combat unit.
These teams have the responsibility to conduct post-combat debriefings of the sort pioneered by Marshall. It has been demonstrated that in this group interview environment, individuals are very careful to tell exactly the truth, even when it reflects poorly upon themselves, since they know that others are there who can catch them at any misrepresentation of the event Williams, F. Thus, the post-combat group interview provides the most accurate and truthful information, in the best possible environment to trigger recall of important data.
It also allows the maximum possible training and learning value and the applications of lessons learned which will assist officers in the execution of their duties in the years to come. But, perhaps the most important aspect of this group debriefing is that it is considered to be the single most powerful therapeutic tool in preventing post-traumatic stress disorder Belenke, G. The moral requirement to provide the therapeutic aspects of this vital group debriefing has been essentially acknowledged by the U. Because of this mental health aspect, it is reasonable that mental health professionals should be present during group interviews.
However, the overall objectives of the mental health practitioner, the prosecutor, the internal affairs officer, and the criminal investigator are all the same in this interview: to simply find out what happened. One experienced individual should be placed in charge of the interview, and he or she should guide the group toward the objective of reconstructing the incident and extracting all available information. Mental health practitioners should address any additional requirements in subsequent group or individual sessions.
The only negative aspect of the group debrief is the potential for contamination in the reconstruction process. This danger is slight, but, nevertheless it must be acknowledged that there is potential for individuals to accept the memories of others which may or may not be correct as their own in the reconstruction process.
It must be pointed out that this is inevitable in any memory reconstruction, and by formalizing this group process it can be ensured that the individuals will be basing their reconstructions on the best possible information. To be absolutely thorough in the information collection process, it is recommended that a second group interview be conducted to hours after the incident. This will permit one or two nights' sleep to process the data presented in the group debriefing, and should therefore provide an opportunity for the most thorough and complete memories to come forward.
At this time, the possibility for contamination is greater, but if the process has been properly handled, the contamination should be minimal, and far less than would have occurred if this overall process had not been followed systematically. The overall application of a scientific understanding of memory processes in a law enforcement environment has potential for tremendous payoff. From better quality eyewitness accounts, to lessons learned and applied, to the long term mental health of the participants, the payoff is simply enormous.
The price for failing to apply these lessons is equally enormous, and the victims of such a failure will inevitably include citizens, officers, the community and, ultimately, Justice. Allport, G. The Psychology of Rumor. New York: Holt. Anderson, R. Recall of previously unrecallable information following a shift in perspective.
Journal of Verbal Learning and Verbal Behavior, , 17, Bacon, S. Arousal and the ranger of cue utilization. Journal of Experimental Psychology, , Bartlet, F. Belenke, G. Bennett, H. Nonverbal response to intraoperative conversations. British Journal of Anesthesia, 57, Benson, K. Psychophysiology, 14, Blaney, P. Affect and memory: a review.