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

View PDF

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.

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

View PDF

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.

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

View PDF

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

View PDF

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.

Normal global-local analysis in patients with dorsolateral frontal lobe lesions

Authors:

• Lynn C. Robertson

• Michele Lazzara

• Robert T. Knight

Date: 1991

PubMed: 1762675

View PDF

Abstract:

The role of prefrontal cortex in the analysis of global and local levels of a visual stimulus was assessed by measuring reaction time to identify a target at one level or the other. Unlike patients with temporal-parietal lesions (STG), there were no global-local performance deficits in right or left prefrontal groups (RFL or LFL). Reallocation of attention to global and local levels was measured by examining changes in performance when the probability of a target appearing at one level or the other varied. While patients with lateral parietal lesions (IPL) have been shown to have deficits in these conditions, both RFL and LFL showed normal changes in performance. In sum, the performance of prefrontal groups differed from both IPL and STG groups but not from normal controls. These results strengthen previous arguments that posterior association cortex is crucial in responding to global and local levels of a pattern.

Component Mechanisms Underlying the Processing of Hierarchically Organized Patterns: Inferences From Patients With Unilateral Cortical Lesions

Authors:

• Michele Lazzara

• Lynn C. Robertson

• Robert T. Knight

Date: 1990

PubMed: 2140405

View PDF

Abstract:

Subjects identified target letters that occurred randomly at the local or global level in a divided attention task. The visual angle of the stimuli was varied. Neurologically intact controls showed a reaction time advantage for local targets which increased as visual angle increased. Patients with lesions centered in the posterior superior temporal gyms (STG) showed a larger local advantage than controls if the lesion was on the right and a global advantage if the lesion was on the left. STG patients were no more influenced by visual angle than were controls. Control subjects also showed the usual interference of global distractors on responding to local targets. STG patients showed little evidence of interference. Control patients with lesions centered in the rostral inferior parietal lobe performed normally. The findings suggest that several component mechanisms are involved in the processing of hierarchical levels of structure, each linked to specific anatomical regions.

Effects of Lesions of Temporal-Parietal Junction on Perceptual and Attentional Processing in Humans

Authors:

• Lynn C. Robertson

• Michele Lazzara

• Robert T. Knight

Date: 1988

PubMed: 3193178

View PDF

Abstract:

When stimuli with larger forms (global) containing smaller forms (local) are presented to subjects with large lesions in the right hemisphere, they are more likely to miss the global form than the local form, whereas subjects with large lesions in the left are more likely to miss the local than the global form. The present study tested whether the global/local impairment in subjects with posterior lesions was due to deficits in controlled attentional processes, passive perceptual processes, or both. Attentional control was examined by measuring reaction time changes when the probability of a target appearing at either the global or local level was varied. Patients with unilateral right or left lesions centered in temporal-parietal regions and age-matched controls served as subjects. Because neurophysiological and neuropsychological evidence have implicated temporal regions in visual discrimination and inferior parietal regions in the allocation of attention to locations in the visual field, patients with left hemisphere lesions were further subdivided into those with lesions centered in the superior temporal gyrus (LSTG) or rostral inferior parietal lobule (LIPL). Patients with right hemisphere injury could not be analogously subdivided. The results revealed that the LSTG group was able to control the allocation of attention to global and local levels normally, while the LIPL group was not. In contrast, the LSTG group showed a strong baseline reaction time advantage toward global targets, while normals and the LIPL group showed no advantage toward one level or the other. Finally, the perceptual component was affected differentially by lesions in the right hemisphere and LSTG, with lesions in the left favoring global targets and lesions in the right favoring local targets. These findings indicate that the hemispheric global/local asymmetry is due to a perceptual mechanism with a critical anatomical locus centered in the STG.

Attention and interference in the processing of global and local information: effects of unilateral temporal-parietal junction lesions

Authors:

• Michele Lazzara

• Lynn C. Robertson

• Robert T. Knight

Date: 1988

View PDF

Abstract:

The processing of hierarchical stimuli was examined in patients with lesions in the temporal-parietal junction. In separate blocks of trials, subjects were instructed to identify the letter at the local or the global level of a hierarchical stimulus. Consistent with previous findings, reaction times for controls were faster in the globally than in the locally directed condition and reaction times to the local level were longer when the letters at the two levels were different (e.g. local "S"s forming a global "H") than when they were the same (e.g. local "S"s forming a global "S"). In other words, controls exhibited interference when locally directed. Patients with lesions centered in the rostral inferior parietal lobe (IPL) showed interference effects similar to controls. In contrast, patients with lesions centered in the posterior superior temporal gyrus and adjacent caudal inferior parietal lobe (STG) showed no interference. The data suggest that the posterior superior temporal plane and adjacent caudal inferior parietal lobe plays an important role in the integration of and/or attention to local and global level information.