Learning and Memory: The Remember-Know Task
Source: Laboratories of Jonas T. Kaplan and Sarah I. Gimbel—University of Southern California
Our experience of memory is varied and complex. Sometimes we remember events in vivid detail, while other times we may only have a vague sense of familiarity. Memory researchers have made a distinction between memories that are recollected versus those that are familiar. A recollected item is one that is not only remembered, but carries with it details of the time at which it was learned or encoded. Like a recollected item, a familiar item is also remembered, but is void of any details about the circumstances surrounding its encoding. Many studies of recollection and familiarity have focused on the medial temporal lobe (MTL), specifically the hippocampus, since its involvement in memory encoding, consolidation, and retrieval is well-known and well-studied.1-3
This video shows how to administer the Remember-Know task4 to compare brain activation in these two types of memory retrieval. In this context, remember is another term for recollection, while know refers to memories that are familiar but not explicitly recollected. In this version of the Remember-Know task, participants are exposed to a series of color images, and asked to remember what they see. Inside an fMRI scanner, they will be exposed to both images that were studied and to novel images, and they will make a "remember," "know," or "new" judgment about each image, indicating what kind of memory they have for that item. Following the scan, whole brain and hippocampal activity will be examined to determine differential activity related to recollection and familiarity. This study is based on a study performed by Gimbel and Brewer.5
1. Participant recruitment
- Recruit 20 participants.
- Participants should be right-handed and have no history of neurological or psychological disorders.
- Participants should have normal or corrected-to-normal vision to ensure that they will be able to see the visual cues properly.
- Participants should not have metal in their body. This is an important safety requirement due to the high magnetic field involved in fMRI.
- Participants should not suffer from claustrophobia
Regions more active for remember responses than for know responses are shown in Figure 1. Notably, the hippocampus, a structure located in the MTL and known to be involved in many stages of memory formation and retrieval, showed greater activity for remember compared with know trials.
Figure 1:
This experiment demonstrates how cognitive neuroscientists attempt to tease apart the specific contributions of a brain region to a cognitive task. Isolating subtle variations within a cognitive domain, in this case the different subjective experiences associated with memory retrieval, can reveal dissociations in the neural systems that support those functions. Understanding how the brain functions during different types of memory retrieval is important for understanding memory impairments such as those that result from
- Bayley, P.J. & Squire, L.R. Failure to acquire new semantic knowledge in patients with large medial temporal lobe lesions. Hippocampus 15, 273-280 (2005).
- Cohen, N.J. & Squire, L.R. Preserved learning and retention of pattern-analyzing skill in amnesia: dissociation of knowing how and knowing that. Science 210, 207-210 (1980).
- Scoville, W.B. & Milner, B. Loss of recent memory after bilateral hippocampal lesions. J Neurol Neurosurg Psychiatry 20, 11-21 (1957).
- Yonelinas, A.P. Components of episodic memory: the contribution of recollection and familiarity. Philos Trans R Soc Lond B Biol Sci 356, 1363-1374 (2001).
- Gimbel, S.I. & Brewer, J.B. Reaction time, memory strength, and fMRI activity during memory retrieval: Hippocampus and default network are differentially responsive during recollection and familiarity judgments. Cogn Neurosci 2, 19-23 (2011).
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