Damage to the prefrontal cortex impairs familiarity but not recollection memory

Authors:

• Mariam Aly

• Andrew P. Yonelinas

• Mark M. Kishiyama

• Robert T. Knight

Date: 2011

PubMed: 21827792

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Abstract:

Frontal lobe lesions impair recognition memory but it is unclear whether the deficits arise from impaired recollection, impaired familiarity, or both. In the current study, recognition memory for verbal materials was examined in patients with damage to the left or right lateral prefrontal cortex. Words were incidentally encoded under semantic or phonological orienting conditions, and recognition memory was tested using a 6-point confidence procedure. Receiver operating characteristics (ROCs) were examined in order to measure the contributions of recollection and familiarity to recognition memory. In both encoding conditions, lateral prefrontal cortex damage led to a deficit in familiarity but not recollection. Similar deficits were observed in left and right hemisphere patients. The results indicate that the lateral prefrontal cortex plays a critical role in the monitoring or decision processes required for accurate familiarity-based recognition responses.

The medial temporal lobe supports conceptual implicit memory

Authors:

• Wei-Chun Wang

• Michele Lazzara

• Charan Ranganath

• Robert T. Knight

• Andrew P. Yonelinas

Date: 2010

DOI: 10.1016/j.neuron.2010.11.009

PubMed: 21144998

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Abstract:

The medial temporal lobe (MTL) is generally thought to be critical for explicit, but not implicit, memory. Here, we demonstrate that the perirhinal cortex (PRc), within the MTL, plays a role in conceptuallydriven implicit memory. Amnesic patients with MTL lesions that converged on the left PRc exhibited defi- cits on two conceptual implicit tasks (i.e., exemplar generation and semantic decision). A separate functional magnetic resonance imaging (fMRI) study in healthy subjects indicated that PRc activation during encoding of words was predictive of subsequent exemplar generation. Moreover, across subjects, the magnitude of the fMRI and behavioral conceptual priming effects were directly related. Additionally, the PRc region implicated in the fMRI study was the same region of maximal lesion overlap in the patients with impaired conceptual priming. These patient and imaging results converge to suggest that the PRc plays a critical role in conceptual implicit memory, and possibly conceptual processing in general.

Faces are special but not too special: spared face recognition in amnesia is based on familiarity

Authors:

• Mariam Aly

• Robert T. Knight

• Andrew P. Yonelinas

Date: 2010

DOI: 10.1016/j.neuropsychologia.2010.09.005

PubMed: 20833190

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Abstract:

Most current theories of human memory are material-general in the sense that they assume that the medial temporal lobe (MTL) is important for retrieving the details of prior events, regardless of the specific type of materials. Recent studies of amnesia have challenged the material-general assumption by suggesting that the MTL may be necessary for remembering words, but is not involved in remembering faces. We examined recognition memory for faces and words in a group of amnesic patients, which included hypoxic patients and patients with extensive left or right MTL lesions. Recognition confidence judgments were used to plot receiver operating characteristics (ROCs) in order to more fully quantify recognition performance and to estimate the contributions of recollection and familiarity. Consistent with the extant literature, an analysis of overall recognition accuracy showed that the patients were impaired at word memory but had spared face memory. However, the ROC analysis indicated that the patients were generally impaired at high confidence recognition responses for faces and words, and they exhibited significant recollection impairments for both types of materials. Familiarity for faces was preserved in all patients, but extensive left MTL damage impaired familiarity for words. These results show that face recognition may appear to be spared because performance tends to rely heavily on familiarity, a process that is relatively well preserved in amnesia. In addition, the findings challenge material-general theories of memory, and suggest that both material and process are important determinants of memory performance in amnesia.

Novelty Enhancements in Memory Are Dependent on Lateral Prefrontal Cortex

Authors:

• Mark M. Kishiyama

• Andrew P. Yonelinas

• Robert T. Knight

Date: 2009

DOI: 10.1523/JNEUROSCI.5507-08.2009

PubMed: 19553451

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Abstract:

Physiological evidence indicates thatseveral brain regions, including the medial temporal lobes and prefrontal cortex (PFC), are involved in processing events that are novel or distinctive in their immediate context. However, behavioral studies that investigate whether these regions are critical for producing stimulus novelty advantages in memory are limited. For example, evidence from an animal lesion study indicated that the PFC is involved in stimulus novelty effects, but this has not been examined in humans. In the current study, we used a von Restorff novelty paradigm to testa large cohortof lateral PFC patients (n
16). We found thatpatients with lateral PFC damage were impaired in recollection- and familiarity-based recognition, and they did not exhibit a normal memory advantage for novel compared with non-novel items. These results provide neuropsychological evidence supporting a key role for the lateral PFC in producing stimulus novelty advantages in memory.

Mild hypoxia disrupts recollection, not familiarity

Authors:

• Andrew P. Yonelinas

• Joel R. Quamme

• Keith F. Widaman

• Neal E. A. Kroll

• Mary Jane Sauve

• Robert T. Knight

Date: 2004

PubMed: 15535174

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Abstract:

Yonelinas et al. (2002) found that hypoxic patients exhibited deficits in recollection that left familiarity relatively unaffected. In contrast, Manns, Hopkins, Reed, Kitchener, and Squire (2003) studied a group of hypoxic patients who suffered severe and equivalent deficits in recollection and familiarity. We reexamine those studies and argue that the discrepancy in results is likely due to differences in the hypoxic groups that were tested (i.e., differences in amnestic severity, subject sampling methods, and patient etiology). Yonelinas et al. examined memory in 56 cardiac arrest patients who suffered a brief hypoxic event, whereas Manns et al. examined a group of severely amnesic patients that consisted of 2 cardiac arrest patients, 2 heroin overdose patients, 1 carbon monoxide poisoning patient, and 2 patients with unknown etiologies. We also consider an alternative explanation proposed by Wixted and Squire (2004), who argued that the two patient groups suffered similar deficits, but that statistical or methodological artifacts distorted the results of each of Yonelinas et al.'s experiments. A consideration of those results, however, indicates that such an explanation does not account for the existing data. All of the existing evidence indicates that recollection, but not familiarity, is disrupted in mild hypoxic patients. In more severe cases of hypoxia, or those with more complex etiologies such as heroin overdose, more profound deficits may be observed.

The neural substrates of visual implicit memory: do the two hemispheres play different roles?

Authors:

• Neal E. A. Kroll

• Andrew P. Yonelinas

• Mark M. Kishiyama

• Kathleen Baynes

• Robert T. Knight

• Michael S. Gazzaniga

Date: 2003

PubMed: 14511536

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Abstract:

Identification of visually presented words is facilitated by implicit memory, or visual priming, for past visual experiences with those words. There is disagreement over the neuro-anatomical substrates of this form of implicit memory. Several studies have suggested that this form of priming relies on a visual word-form system localized in the right occipital lobe, whereas other studies have indicated that both hemispheres are equally involved. The discrepancies may be related to the types of priming tasks that have been used because the former studies have relied primarily on word-stem completion tasks and the latter on tasks like word-fragment completion. The present experiments compared word-fragment and word-stem measurements of visual implicit memory in patients with right occipital lobe lesions and patients with complete callosotomies. The patients showed normal visual implicit memory on fragment completion tests, but essentially no visual priming on standard stem completion tests. However, when we used a set of word stems that had only one correct solution for each test item, as was true of the items in the fragment completion tests, the patients showed normal priming effects. The results indicate that visual implicit memory for words is not solely dependent upon the right hemisphere, rather it reflects changes in processing efficiency in bilateral visual regions involved in the initial processing of the items. However, under conditions of high lexical competition (i.e., multiple completion word stems), the lexical processes, which are dominant in the left hemisphere, overshadow the visual priming supported by the left hemisphere.

Effects of extensive temporal lobe damage or mild hypoxia on recollection and familiarity

Authors:

• Andrew P. Yonelinas

• Neal E. A. Kroll

• Joel R. Quamme

• Michele Lazzara

• Mary Jane Sauve

• Keith F. Widaman

• Robert T. Knight

Date: 2002

PubMed: 12379865

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Abstract:

Memory for past events can be based on recollection or on assessments of familiarity. These two forms of human memory have been studied extensively by philosophers and psychologists, but their neuroanatomical substrates are largely unknown. Here we examined the brain regions that are involved in these two forms of memory by studying patients with damage to different temporal lobe regions. Our results come from (i) structural covariance modeling of recall and recognition, (ii) introspective reports during recognition and (iii) analysis of receiver operating characteristics. In sum, we found that the regions disrupted in mild hypoxia, such as the hippocampus, are centrally involved in conscious recollection, whereas the surrounding temporal lobe supports familiarity-based memory discrimination.

Visual implicit memory in the left hemisphere: evidence from patients with callosotomies and right occipital lobe lesions

Authors:

• Andrew P. Yonelinas

• Neal E. A. Kroll

• Kathleen Baynes

• Ian G. Dobbins

• C.M. Frederick

• Robert T. Knight

• Michael S. Gazzaniga

Date: 2001

PubMed: 11476095

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Abstract:

Identification of visually presented objects and words is facilitated by implicit memory for past visual experiences with those items. Several behavioral and neuroimaging studies suggest that this form of memory is dependent on perceptual processes localized in the right occipital lobe. We tested this claim by examining implicit mem- ory in patients with extensive right occipital lobe lesions, using lexi- cal-decision, mirror-reading, picture-fragment, and word-fragment- completion tests, and found that these patients exhibited normal levels of priming. We also examined implicit memory in patients with com- plete callosotomies, using standard and divided-visual-field word- fragment-completion procedures, and found that the isolated left hemisphere exhibited normal priming effects. The results indicate that the right occipital lobe does not play a necessary role in visual im- plicit memory, and that the isolated left hemisphere can support nor- mal levels of visual priming in a variety of tasks.

The contribution of recollection and familiarity to yes-no and forced-choice recognition tests in healthy subjects and amnesics

Authors:

• Wayne Khoe

• Neal E. A. Kroll

• Andrew P. Yonelinas

• Ian G. Dobbins

• Robert T. Knight

Date: 2000

PubMed: 10869576

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Abstract:

Recent reports suggest that some amnesic patients perform relatively normally on forced-choice recognition memory tests. Their preserved performance may re ̄ect the fact that the test relies more heavily on assessments of familiarity, a process that is relatively preserved in these patients, than do other recognition tests such as yes±no tests, which may rely more on recollection. The current study examined recognition memory using yes±no and forced-choice procedures in control and amnesic patients in order to determine whether the two tasks di€erentially relied on recollection and familiarity, and whether the extent of the recognition memory de®cit observed in amnesia was dependent upon the type of recognition test used to measure performance. Results using the remember±know procedure with healthy subjects showed that there were no substantial di€erences in recognition accuracy or in the contribution of recollection to these two tasks. Moreover, amnesic patients were not found to perform better on a forced-choice test than on a yes±no test, suggesting that familiarity contributed equally to these two types of recognition test.

The neural substrates of recollection and familiarity (pp. 468-469)

Authors:

• Andrew P. Yonelinas

• Neal E. A. Kroll

• Ian G. Dobbins

• Michele Lazzara

• Robert T. Knight

Date: 1999

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Abstract:

Aggleton & Brown argue that a hippocampal-anterior thalamic system supports the “recollection” of contextual information about previ- ous events, and that a separate perirhinal-medial dorsal thalamic system supports detection of stimulus “familiarity.” Although there is a growing body of human literature that is in agreement with these claims, when rec- ollection and familiarity have been examined in amnesics using the process dissociation or the remember/know procedures, the results do not seem to provide consistent support. We reexamine these studies and describe the results of an additional experiment using a receiver operating charac- teristic (ROC) technique. The results of the reanalysis and the ROC ex- periment are consistent with Aggleton & Brown’s proposal. Patients with damage to both regions exhibit severe deficits in recollection and smaller, but consistent, deficits in familiarity.

Recollection and familiarity deficits in amnesia: convergence of remember-know, process dissociation, and receiver operating characteristic data

Authors:

• Andrew P. Yonelinas

• Neal E. A. Kroll

• Ian G. Dobbins

• Michele Lazzara

• Robert T. Knight

Date: 1998

PubMed: 9673991

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Abstract:

Previous studies using the process dissociation and the remember-know procedures led to conflicting conclusions regarding the effects of anterograde amnesia on recollection and familiarity. We argue that these apparent contradictions arose because different models were used to interpret the results and because differences in false-alarm rates between groups biased the estimates provided by those models. A reanalysis of those studies with a dual-process signal-detection model that incorporates response bias revealed that amnesia led to a pronounced reduction in recollection and smaller but consistent reduction in familiarity. To test the assumptions of the model and to further assess recognition deficits in amnesics, we examined receiver operating characteristics (ROCs) in amnesics and controls. The ROCs of the controls were curved and asymmetrical, whereas those of the amnesics were curved and symmetrical. The results supported the predictions of the model and indicated that amnesia was associated with deficits in both recollection and familiarity.