Matthew D. Grilli

Imagine that: Self-imagination improves prospective memory in memory-impaired individuals with neurological damage

Recent research has demonstrated that “self-imagination” – a mnemonic strategy developed by Grilli and Glisky (2010) – enhances episodic memory in memory-impaired individuals with neurological damage more than traditional cognitive strategies, including semantic elaboration and visual imagery. The present study investigated the effect of self-imagination on prospective memory in individuals with neurologically based memory deficits. In two separate sessions, 12 patients with memory impairment took part in a computerised general knowledge test that required them to answer multiple choice questions (i.e., ongoing task) and press the “1” key when a target word appeared in a question (i.e., prospective memory task). Prior to the start of the general knowledge test in each session, participants attempted to encode the prospective memory task with one of two strategies: self-imagination or rote-rehearsal. The findings revealed a “self-imagination effect (SIE)” in prospective memory as self-imagining resulted in better prospective memory performance than rote-rehearsal. These results demonstrate that the mnemonic advantage of self-imagination extends to prospective memory in memory-impaired individuals with neurological damage and suggest that self-imagination has potential in cognitive rehabilitation.

Personal semantic memory: Insights from neuropsychological research on amnesia

This paper provides insight into the cognitive and neural mechanisms of personal semantic memory, knowledge that is specific and unique to individuals, by reviewing neuropsychological research on stable amnesia secondary to medial temporal lobe damage. The results reveal that personal semantic memory does not depend on a unitary set of cognitive and neural mechanisms. Findings show that autobiographical fact knowledge reflects an experience-near type of personal semantic memory that relies on the medial temporal lobe for retrieval, albeit less so than personal episodic memory. Additional evidence demonstrates that new autobiographical fact learning likely relies on the medial temporal lobe, but the extent to which remains unclear. Other findings show that retrieval of personal traits/roles and new learning of personal traits/roles and thoughts/beliefs are independent of the medial temporal lobe and thus may represent highly conceptual types of personal semantic memory that are stored in the neocortex.

The life stories of adults with amnesia: Insights into the contribution of the medial temporal lobes to the organization of autobiographical memory

ABSTRACT Autobiographical memories are not stored in isolation but rather are organized into life chapters, higher‐order knowledge structures that represent major themes conveying the arc of ones life. Neuropsychological studies have revealed that both episodic memory and some aspects of personal semantic memory are impaired in adults with medial temporal lobe (MTL) damage. However, whether such impairment compromises the retrieval and formation of life chapters is unknown. Therefore, we had 10 adults with MTL amnesia and 20 control participants narrate their life stories, and we extracted life chapters from these narratives using a novel scoring protocol. For the retrograde and anterograde time period separately, we evaluated the number of life chapters and assessed their quality, as indexed by measures of complexity and richness. Additionally, to investigate the idea that formation of life chapters occurs on a protracted time scale, we separated the amnesic participants into an early‐life and a later‐life onset subgroup. Results revealed that early‐onset, but not later‐onset, amnesic participants generated fewer retrograde life chapters than controls. The higher‐order temporal relation among retrograde chapters, but not their thematic relation or the richness of individual life chapters, was impaired in both amnesic subgroups. The amnesic participants also generated fewer anterograde life chapters than controls, and the richness of their anterograde chapters was reduced in terms of content, but not self‐reflection. Findings suggest that the organization of autobiographical content into life chapters is a protracted process that depends on the MTL, as does retrieval of higher order temporal relations among life chapters. HighlightsWe investigated life chapters in individuals with MTL amnesia.Life chapters, once firmly established, can be maintained independent of the MTL.The formation of life chapters is a protracted process that depends on the MTL.The MTL also supports higher‐order temporal relations among life chapters.

Imagining a Better Memory Self-Imagination in Memory-Impaired Patients

Recent research has demonstrated that self-referential strategies can be applied to improve memory in memory-impaired populations. However, little is known regarding the mnemonic mechanisms and relative effectiveness of self-referential strategies in memory-impaired individuals. This study investigated the benefit of a new self-referential strategy known as self-imagination, traditional self-referential strategies, and non-self-referential strategies on free recall in memory-impaired patients with acquired brain injury and in healthy control respondents. The data revealed an advantage of self-imagining in free recall relative to all other strategies in patients and control respondents. Findings also demonstrated that, in the patients only, a self-referential strategy that relied on semantic information in self-knowledge was more effective than a self-referential strategy that relied on autobiographical episodic information. This study provides new evidence to support the clinical utility of self-imagining as a memory strategy and has implications for the future development and implementation of self-referential strategies in memory rehabilitation.

Impaired personal trait knowledge, but spared other-person trait knowledge, in an individual with bilateral damage to the medial prefrontal cortex

Functional neuroimaging has revealed that in healthy adults retrieval of personal trait knowledge is associated with increased activation in the medial prefrontal cortex (mPFC). Separately, neuropsychology has shown that the self-referential nature of memory can be disrupted in individuals with mPFC lesions. However, it remains unclear whether damage to the mPFC impairs retrieval of personal trait knowledge. Therefore, in this neuropsychological case study we investigated the integrity of personal trait knowledge in J.S., an individual who sustained bilateral damage to the mPFC as a result of an anterior communicating artery aneurysm. We measured both accuracy and consistency of J.S.s personal trait knowledge as well as his trait knowledge of another, frequently seen person, and compared his performance to a group of healthy adults. Findings revealed that J.S. had severely impaired accuracy and consistency of his personal trait knowledge relative to control participants. In contrast, J.S.s accuracy and consistency of other-person trait knowledge was intact in comparison to control participants. Moreover, J.S. showed a normal positivity bias in his trait ratings. These results, albeit based on a single case, implicate the mPFC as critical for retrieval of personal trait knowledge. Findings also cast doubt on the likelihood that the mPFC, in particular the ventral mPFC, is necessary for storage and retrieval of trait knowledge of other people. Therefore, this case study adds to a growing body of evidence that mPFC damage can disrupt the link between self and memory.

Self-reference and emotional memory effects in older adults at increased genetic risk of Alzheimer’s disease

ABSTRACT The present study investigated whether cognitively healthy older adults who are carriers of the ε4 allele of apolipoprotein E, the most prevalent genetic risk factor for late-onset Alzheimer’s disease, benefit from self-referential processing and emotional processing to the same degree as noncarriers of this gene. Participants encoded emotional and nonemotional narratives using a baseline-orienting task, semantic elaboration, or imagination-based self-referential processing and then completed a recognition memory test. Both groups of older adults showed enhanced recognition memory for narrative information following self-referential processing relative to semantic elaboration, and the magnitude of this memory effect was not affected by ε4 status. However, older adult ε4 carriers did not show an emotional enhancement effect, whereas older adult ε4 noncarriers did. These results indicate that whereas the self-reference effect is not attenuated in cognitively healthy older adults ε4 carriers, deficits in emotional memory may be an early cognitive marker of abnormal decline.

The association of personal semantic memory to identity representations: insight into higher-order networks of autobiographical contents

ABSTRACT Identity representations are higher-order knowledge structures that organise autobiographical memories on the basis of personality and role-based themes of one’s self-concept. In two experiments, the extent to which different types of personal semantic content are reflected in these higher-order networks of memories was investigated. Healthy, young adult participants generated identity representations that varied in remoteness of formation and verbally reflected on these themes in an open-ended narrative task. The narrative responses were scored for retrieval of episodic, experience-near personal semantic and experience-far (i.e., abstract) personal semantic contents. Results revealed that to reflect on remotely formed identity representations, experience-far personal semantic contents were retrieved more than experience-near personal semantic contents. In contrast, to reflect on recently formed identity representations, experience-near personal semantic contents were retrieved more than experience-far personal semantic contents. Although episodic memory contents were retrieved less than both personal semantic content types to reflect on remotely formed identity representations, this content type was retrieved at a similar frequency as experience-far personal semantic content to reflect on recently formed identity representations. These findings indicate that the association of personal semantic content to identity representations is robust and related to time since acquisition of these knowledge structures.

The contribution of the left anterior ventrolateral temporal lobe to the retrieval of personal semantics

ABSTRACT Autobiographical facts and personal trait knowledge are conceptualized as distinct types of personal semantics, but the cognitive and neural mechanisms that separate them remain underspecified. One distinction may be their level of specificity, with autobiographical facts reflecting idiosyncratic conceptual knowledge and personal traits representing basic level category knowledge about the self. Given the critical role of the left anterior ventrolateral temporal lobe (AVTL) in the storage and retrieval of semantic information about unique entities, we hypothesized that knowledge of autobiographical facts may depend on the integrity of this region to a greater extent than personal traits. To provide neuropsychological evidence relevant to this issue, we investigated personal semantics, semantic knowledge of non‐personal unique entities, and episodic memory in two individuals with well‐defined left (MK) versus right (DW) AVTL lesions. Relative to controls, MK demonstrated preserved personal trait knowledge but impaired “experience‐far” (i.e., spatiotemporal independent) autobiographical fact knowledge, semantic memory for non‐personal unique entities, and episodic memory. In contrast, both experience‐far autobiographical facts and personal traits were spared in DW, whereas episodic memory and aspects of semantic memory for non‐personal unique entities were impaired. These findings support the notion that autobiographical facts and personal traits have distinct cognitive features and neural mechanisms. They also suggest a common organizing principle for personal and non‐personal semantics, namely the specificity of such knowledge to an entity, which is reflected in the contribution of the left AVTL to retrieval. HighlightsWe focused on the role of specificity in the organization of personal semantics.We assessed two patients with anterior ventrolateral temporal lobe (AVTL) lesions.Autobiographical facts but not personal traits were impaired by left AVTL lesions.Both types of personal semantics were spared by right AVTL lesions.We conclude that specificity separates autobiographical facts from personal traits.

Self-reference enhances relational memory in young and older adults

ABSTRACT The present study investigated the influence of self-reference on two kinds of relational memory, internal source memory and associative memory, in young and older adults. Participants encoded object–location word pairs using the strategies of imagination and sentence generation, either with reference to themselves or to a famous other (i.e., George Clooney or Oprah Winfrey). Both young and older adults showed memory benefits in the self-reference conditions compared to other-reference conditions on both tests, and the self-referential effects in older adults were not limited by low memory or executive functioning. These results suggest that self-reference can benefit relational memory in older adults relatively independently of basic memory and executive functions.