Coherence, cohesion, and declarative memory: Discourse patterns in patients with hippocampal amnesia

Research on discursive cohesion and coherence has focused on patient groups with diffuse damage and widespread cognitive impairment (e.g.,TBI, dementia). Consequently, attempts to attribute discourse deficits to a particular cognitive domain has proven difficult. The current study capitalizes on a rare patient group with selective and severe anterograde hippocampal amnesia to investigate the contribution of declarative memory to discourse cohesion and coherence across a range of discourse genres. This research contributes to our understanding of the interdependent relationship between language and memory and promises to inform clinical decision making for individuals with complex cognitive-communication disorders following TBI and dementia

The hippocampus and the flexible use and processing of language

Fundamental to all human languages is an unlimited expressive capacity and creative flexibility that allow speakers to rapidly generate novel and complex utterances. In turn, listeners interpret language “on-line,” incrementally integrating multiple sources of information as words unfold over time. A challenge for theories of language processing has been to understand how speakers and listeners generate, gather, integrate, and maintain representations in service of language processing. We propose that many of the processes by which we use language place high demands on and receive contributions from the hippocampal declarative memory system. The hippocampal declarative memory system is long known to support relational binding and representational flexibility. Recent findings demonstrate that these same functions are engaged during the real-time processes that support behavior in-the-moment. Such findings point to the hippocampus as a potentially key contributor to cognitive functions that require on-line integration of multiple sources of information, such as on-line language processing. Evidence supporting this view comes from findings that individuals with hippocampal amnesia show deficits in the use of language flexibly and on-line. We conclude that the relational binding and representational flexibility afforded by the hippocampal declarative memory system positions the hippocampus as a key contributor to language use and processing

Focal ventromedial prefrontal cortex damage impairs convergence in discourse

Conversational partners tend to converge (become more similar) on various speech and discourse characteristics, enhancing social affiliation. We examined convergence in the discourse of eight participants with bilateral ventromedial prefrontal cortex (VMPC) damage and eight healthy comparison participants (NC) each interacting with a clinician. Changes in total words, words/turn, and backchannels were assessed across the interaction by comparing the first ¼ and last ¼ of the session. Preliminary results suggest that convergence was displayed in NC interactions as conversational partners become more similar to one another across variables. In striking contrast, VMPC interactions did not display convergence across any variables

Conversational narratives and aphasia

Research has highlighted the pervasiveness of narratives in conversational contexts across the lifespan (e.g., Basso, 1979; Linde, 1993; Ochs & Capps, 2001; Miller et al., 2000). This study, exploring conversational narratives in interactions between individuals with aphasia and their partners, presents: 1) a framework operationally defining conversational narratives and categorizing them by type and pattern of production; 2) a systematic analysis of a small corpus of data (10 sessions with 5 participant pairs) using that framework; and 3) a situated discourse analysis of striking narrative examples, exploring social and discursive functions of conversational narratives for these participants

Health education programs: a global opportunity for reconciliation

Health Education Programs (HEP) provide an opportunity to address many of the calls to action for reconciliation. This workshop will explore current global strategies for addressing the reconciliation recommendations within international HEP. Indigenous nursing associations make several key recommendations on how HEP can make a difference to Indigenous reconciliation outcomes. This workshop invites the participants to contribute to the discussion on best models for the development and delivery of HEP, which aim to address these recommendations. Aligns With Truth and Reconciliation: This workshops aligns with the actions on health (18, 19), Church Apologies and Reconciliation (61i, ii, iii, iv), exploring the concerns of increasing Indigenous student enrolment and graduation numbers, the inclusion of culturally appropriate curriculum and localised decision making

Distributed impact of cognitive-communication impairment: Disruptions in the use of definite references when speaking to individuals with amnesia

Definite references signal the belief that listeners can uniquely identify referents. Our previous research found participants with amnesia used fewer definite references, as directors in a barrier task, than comparison participants. If this is an interactional consequence of managing memory impairments (as opposed to a language deficit), we should expect a decrease in definite referencing by their communication partners. This paper presents a follow-up study in which the communication partners became directors. In addition to documenting the communicative and linguistic consequences of amnesia in interaction, this analysis may have implications for basic models of common ground

Procedural Memory Following Moderate-Severe Traumatic Brain Injury: Group Performance and Individual Differences on the Rotary Pursuit Task

The impact of traumatic brain injury (TBI) on procedural memory has received significantly less attention than declarative memory. Although to date studies on procedural memory have yielded mixed findings, many rehabilitation protocols (e.g., errorless learning) rely on the procedural memory system, and assume that it is relatively intact. The aim of the current study was to determine whether individuals with TBI are impaired on a task of procedural memory as a group, and to examine the presence of individual differences in performance. We administered to a sample of 36 individuals with moderate-severe TBI and 40 healthy comparisons (HCs) the rotary pursuit task, and then examined their rate of learning, as well as their retention of learning. Our analyses revealed that while individuals with TBI spent a significantly shorter amount of time on target as a group, they did not retain significantly less procedural learning, and as a group their rate of learning was not different from HCs. However, there were high individual differences in both groups, indicating that some individuals might not be able to take advantage of treatment methods designed to leverage intact procedural memory system. Future work is needed to better assess and characterize procedural memory in individuals with TBI across a larger battery of tasks in experimental and clinical setting as memory and learning status may predict rehabilitation success

Medial Temporal Lobe Damage Impairs Representation of Simple Stimuli

Medial temporal lobe (MTL) damage in humans is typically thought to produce a circumscribed impairment in the acquisition of new enduring memories, but recent reports have documented deficits even in short-term maintenance. We examined possible maintenance deficits in a population of MTL amnesics, with the goal of characterizing their impairments as either representational drift or outright loss of representation over time. Patients and healthy comparisons performed a visual search task in which the similarity of various lures to a target was varied parametrically. Stimuli were simple shapes varying along one of several visual dimensions. The task was performed in two conditions, one presenting a sample target simultaneously with the search array and the other imposing a delay between sample and array. Eye-movement data collected during search revealed that the duration of fixations to items varied with lure-target similarity for all participants, i.e., fixations were longer for items more similar to the target. In the simultaneous condition, patients and comparisons exhibited an equivalent effect of similarity on fixation durations. However, imposing a delay modulated the effect differently for the two groups: in comparisons, fixation duration to similar items was exaggerated; in patients, the original effect was diminished. These findings indicate that MTL lesions subtly impair short-term maintenance of even simple stimuli, with performance reflecting not the complete loss of the maintained representation but rather a degradation or progressive drift of the representation over time

Relationship between individual differences in functional connectivity and facial emotion recognition abilities in traumatic brain injury

Although several studies have demonstrated that facial-affect recognition impairment is common following moderate-severe traumatic brain injury (TBI), and that there are diffuse alterations in large-scale functional brain networks in TBI populations, little is known about the relationship between the two. Here, in a sample of26 participants with TBI and 20 healthy comparison participants (HC) we measured facial-affect recognition abilities and resting-state functional connectivity (rs-FC) using fMRI. We then used network-based statistics to ex-amine (A) the presence of rs-FC differences between individuals with TBI and HC within the facial-affect processing network, and (B) the association between inter-individual differences in emotion recognition skills and rs-FC within the facial-affect processing network. We found that participants with TBI showed significantly lower rs-FC in a component comprising homotopic and within-hemisphere, anterior-posterior connections with-in the facial-affect processing network. In addition, within the TBI group, participants with higher emotion-labeling skills showed stronger rs-FC within a network comprised of intra- and inter-hemispheric bilateral connections. Findings indicate that the ability to successfully recognize facial-affect after TBI is related to rs-FC within components of facial-affective networks, and provide new evidence that further our understanding of the mechanisms underlying emotion recognition impairment in TBI

Hippocampal Amnesia Impairs All Manner of Relational Memory

Relational memory theory holds that the hippocampus supports, and amnesia following hippocampal damage impairs, memory for all manner of relations. Unfortunately, many studies of hippocampal-dependent memory have either examined only a single type of relational memory or conflated multiple kinds of relations. The experiments reported here employed a procedure in which each of several kinds of relational memory (spatial, associative, and sequential) could be tested separately using the same materials. In Experiment 1, performance of amnesic patients with medial temporal lobe (MTL) damage was assessed on memory for the three types of relations as well as for items. Compared to the performance of matched comparison participants, amnesic patients were impaired on all three relational tasks. But for those patients whose MTL damage was limited to the hippocampus, performance was relatively preserved on item memory as compared to relational memory, although still lower than that of comparison participants. In Experiment 2, study exposure was reduced for comparison participants, matching their item memory to the amnesic patients in Experiment 1. Relational memory performance of comparison subjects was well above amnesic patient levels, showing the disproportionate dependence of all three relational memory performances on the integrity of the hippocampus. Correlational analyses of the various task performances of comparison participants and of college-age participants showed that our measures of item memory were not influenced significantly by memory for associations among the items