Amnesia and damage to the frontal lobes
In this work I will talk about characteristic memory deficits in frontal damage, prospective memory and executive functioning and the role of prefrontal cortex in memory.
Characteristic memory deficits in frontal damage
Memory alterations that are associated with frontal damage show distinctive characteristics regarding memory alterations that derive from other lesions such as those related to temporary or diencephalic damage.
Several studies claim that temporary brain injury predominantly affects recent memory, in other words, the ability to establish new learning and retain new information. We can talk here about anterograde amnesia, which is the inability to remember information and facts lived after the injury appears. The deterioration of free memory suggests that the frontal region is involved in the use of memory strategies and this could be crossed with another frequent deficit, the great difficulty of ignoring or inhibiting irrelevant information.
One of the deficits that are most related to the frontal function is the amnesia of the source, contextual amnesia or attribution amnesia. This amnesia is observed when a person correctly remembers information or a specific fact, but fails to remember when or where that information was acquired, does not remember the source of knowledge. This alteration is associated with people with prefrontal damage. The studies of this amnesia suggest that there is an appearance of the memora that is injured, the space-time context, which is more related to the frontal region than with the areas related to amnesia, temporal and diencephalical regions.
Some studies indicate that patients with prefrontal lesions confuse the temporal order and the relative frequency of events that occurred in the past, these people recognize the stimuli that occur previously, but cannot estimate the frequency of their presentation. The consequences of this is that these patients will not be able to perform realistic predictions about the future and may not be prepared for certain events.
Prospective memory and executive functioning
Prospective memory deficit is related to one of the most important memory alterations in people with dysfunction or frontal damage. The day -to -day memora is not only responsible for remembering events of the past, but also to store plans and intentions, allows to carry out a desired plan or action at a certain moment of the future and at the same time continue with the activity we were developing from background. This is the prospective memory, according to Kvavilashivli and Ellis (1996) is "the memory of doing something at a specific moment in the future or the most timely execution according to the previously formulated intention or plan".
The prospective memory deficit would affect when remembering and going to an appointment or a medical review, taking the medication or doing something they have sent. To develop a prospective memory activity, six components according to Dobbs and Reeves (1996) are necessary, and these are not unit components since there is a certain overlap between them.
- Metacancimiento: specific knowledge specific to action.
- Planning: Plan formulation to facilitate its realization.
- Monitoring: monitoring of the activity to be carried out, to complete the task, evaluate whether the necessary circumstances are present.
- Memory content: remember the content of the action to be carried out.
- Conformity: the person’s agreement or will to perform the action at the appropriate time.
- "Output monitor": Check the performance of the realization, remember whether the action was carried out or not.
The components are qualitatively different and interact between them and this interaction influences the final result of the action. In prospective memory we can find relationships between its components and interaction with other types of memory, such as retrospective.
Retrospective memory is to remember the past and prospective in remembering the future. According to Baddeley and Wilkins (1984) there is no distinction between the two types of memory since the prospective needs certain elements of the retrospective to function. Prospective memory requires certain retrospective memories apart from other additional processes. In other words, retrospective memory is responsible for people to remember and the prospective that people remember to remember.
The two memories differ in the demands to the attentional system. The retrospective pays all its attention to recover the information while in the prospective while the task develops the memory of the task. There are also other differences or small nuances in operation, such as coding level, the signals used or the information recovery phase.
Some investigations suggest that some subjects with prospective memory deficit almost do not present limitations in declarative memory tasks. This leads to thinking that these two types of memory may be dissociated between them and therefore organized separately.
According to SHUM, Valentine and Cutmore (1999), studies demonstrate two main limitations: prospective memory is defined as a unit construct and on other occasions it is studied with little depth. Cohen (1996) states that prospective memory is a difficult task that involves a great variety of different mental processes. Cohen (1989) also defends that within the tasks performed by means.
Einstein, McDaniel, Richardson, Guynn and Cunfer (1995) differentiated the activities carried out through prospective memory according to the external signal type triggen of the action:
- Signal -based signal: remember to perform an action at a specific time or after a certain period of time.
- Signal based on “events or facts”: the development of an action when an external signal or track appears.
The task based on the most difficult “time” signal is considered because it requires more self-infection than in “events or facts” since it does not have any external clue that is the one that warns of prospective memory. Ellis (1988), with respect to the activity based on "time", focused on the level of formulation and specificity of the right time to be developed the action. According to him, the pulses are a prospective plan in which the exact time at which the plan must be taken, on the other there is an indefinite prospective plan is specified, Ellis specifies that the pulses are better reminders than Steps.
Kvavilashvili and Ellis (1996) added the subtype that is based on the "activity", which would be similar to that of "events" because it has an external track, but it is simpler than the tasks based on the "time" and "event" because It does not require that the present activity be interrupted.
According to Shum, Valentine and Cutmore (1999) and Glisky (1996) the performance of prospective memory will be different according to the complexity of the tasks and the processes that are required to perform them. The processes require integrity of the frontal region, but the front extension involved will vary according to the type of task. McDaniel, Glisky, Rubin, Guynn and Routhieaux (1999) say that the prefontal region will be more involved when the demand for working memory is important, when a plan is necessary prior to the action, when the task is novel, when required Temporary estimate, when other actions that were being performed or when the environment or context must be monitored.
The prospective memory is involved in the creation of plans, allows each of the steps and the appropriate sequence to be kept in mind to the time in which the Action Plan is carried out, which is evaluated, reviewed and corrected. And the frontal region selects and develops appropriate strategies in unexpected situations, in addition to monitoring effective and correct behaviors and if necessary the ability to modulate and inhibit behavior according to circumstances (Milner and Petrides, 1984). In clinical contexts, prospective memory deficits, designing syndrome and disinhibicon have some common characteristics.
The role of prefrontal cortex in memory
According to Goldstein (1936) after frontal damage does not appear directly an alteration in memory, but interferes with the same Mnesic function. Vilkki, Servo and Surma-Aho (1998) indicate that memory deficits that are associated with a prefrontal lesion apparently reflect deficits in monitoring, planning, organization and other strategic aspects of operational memory.
It seems that frontal lesions create alterations in the ability to create and maintain strategies to organize the cognitive processes necessary for the proper functioning of the Mnesic function. Goldman-Rakic (1998) suggested that somehow the deficits of working memory can be related to the alteration in the ability to organize information.
The difficulty of using information organization strategies has led to thinking that mnesic deficits would be a consequence of the alteration in the recovery process, however many of the memory alterations that are associated with frontal damage can be a consequence of coding problems.
That the deficit in the memory of the source and in the temporal estimate can be explained by the fact that the way in which we plan the coding or store the information highly determines accessibility to memories, because part of the information may not become coded. The theory that the executive processes are involved in the coding and recovery phases has been proven by Shalice, Fletcher, Grasby, Frackiwiak and Dolan (1994) and Tulving, Kapur, Gaik, Moscowistch and Houle (1994). They specify the association of the left frontal lobe with coding operations and the right frontal lobe with the recovery operation.
In conclusion, damage to the frontal region does not interfere in the ability to store information, but in activities that include attention, motivation, programming, regulation and verification (Stuss and Benson, 1986).
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