Fandom

VroniPlag Wiki

Jm/Fragment 017 01

< Jm

31.380Seiten in
diesem Wiki
Seite hinzufügen
Diskussion0 Teilen

Störung durch Adblocker erkannt!


Wikia ist eine gebührenfreie Seite, die sich durch Werbung finanziert. Benutzer, die Adblocker einsetzen, haben eine modifizierte Ansicht der Seite.

Wikia ist nicht verfügbar, wenn du weitere Modifikationen in dem Adblocker-Programm gemacht hast. Wenn du sie entfernst, dann wird die Seite ohne Probleme geladen.


Typus
BauernOpfer
Bearbeiter
Hindemith
Gesichtet
Yes.png
Untersuchte Arbeit:
Seite: 17, Zeilen: 1-25
Quelle: Nadel 2008
Seite(n): 5, 6, Zeilen: 5: r.col: 34-39; 6: l.col: 19-55 - r.col: 1
[As such, the “context” representation that supports] conditioned fear after several weeks is a representation based on elements present in the test situation rather than a configural representation of the whole.

Such an explanation mirrors findings pertaining to the ‘pre-exposure’ effect. In this case, when an animal is given fear training without some exposure to the training context prior to the introduction of the unconditioned stimulus, it fails to learn to associate shock with the “context” understood as the configuration of elements (and their spatial relations) in the chamber. This happens, according to Nadel, because exposure to the shock chamber is essential for the animal to acquire a configural representation of the context in the first place – what is termed a ‘cognitive map’ (O’Keefe & Nadel, 1978), or a contextual representation (Nadel & Willner, 1980). According to Nadel, such a finding parallels what happens over time within the realm of consolidation. Initial training (with pre-exposure) leads the animal to associate fear with the configurally-represented context. As such, the behavior depends upon the hippocampus as well as the amygdala. Over time, and as a direct consequence of what has been termed consolidation, the contextual binding weakens, leaving behind only linkages between elements of the chamber and the shock.

These considerations make it much easier to understand the existing literature concerning context and hippocampal lesion effects and why doubts still exist about hippocampal involvement in context learning (e.g., Gewirtz et al., 2000). When “normal” behavior depends upon a configural representation of context, hippocampal lesions will lead to impairment (Nadel, 2008). This should be the case for both acquisition and retention. When a task is used that can be solved with either a configural or an elemental representation of context, hippocampal lesions will not cause an obvious impairment; rather, special testing methods will have to be used to show that performance differs between animals with hippocampal lesions and control animals. The most obvious method would be to shift the test context.

[page 5]

[Instead of assuming that “memory” is either transferred from hippocampus to neocortex, or given independent status within neocortex after a period of requiring hippocampal help in retrieval,] one can best account for the data by assuming that the “context” representation that supports conditioned fear after several weeks is a representation based on elements in the test situation rather than a configural representation of the whole.

[page 6]

This story connects with what has been learned from studying the pre-exposure effect (cf. Fanselow’s work and Rudy’s work). When an animal is given fear training without some exposure to the training context before US introduction, it fails to learn to associate shock with the “context” understood as the configuration of elements (and their spatial relations) in the chamber. This happens because exposure to the shock chamber is essential for the animal to acquire a configural representation of the context in the first place – what we called a cognitive map (O’Keefe and Nadel, 1978), or a contextual representation (Nadel and Willner, 1980).

I believe that this parallels what happens over time in the consolidation domain. Initial training (with pre-exposure) leads the animal to associate fear with the configurally-represented context. As such, the behavior depends upon the hippocampus as well as the amygdala. Over time, and as a direct consequence of what has been called consolidation, the contextual binding weakens, leaving behind only linkages between elements of the chamber and the shock.

These considerations make it much easier to understand the existing literature on hippocampal lesion effects and context and why doubts still exist about hippocampal involvement in context learning (e.g., Gewirtz et al., 2000). When “normal” behavior depends upon a configural representation of context, hippocampal lesions will lead to impairment. This should be the case in both acquisition and retention. When a task is used that can be solved with either a configural or an elemental representation of context, hippocampal lesions will not cause an obvious impairment; rather, special testing methods will have to be used to show that the basis of performance differs between animals with hippocampal lesions and control animals. The most obvious such method would be to shift the test context.

Anmerkungen

Nadel (2008) is mentioned in the text, but it is not clear to the reader at all that the entire page is copied from the source, which is also not listed in the bibliography.

Sichter
(Hindemith) Schumann

Auch bei Fandom

Zufälliges Wiki