A study of confabulation

It's not a lie … If you believe it: Narrative analysis of autobiographical memories reveals over-confidence disposition in patients who confabulate

Humans perceive their personal memories as fundamentally true, and although memory is prone to inaccuracies, flagrant memory errors are rare. Some patients with damage to the ventromedial prefrontal cortex (vmPFC) recall and act upon patently erroneous memories (spontaneous confabulations). Clinical observations suggest these memories carry a strong sense of confidence, a function ascribed to vmPFC in studies of memory and decision making. However, most studies of the underlying mechanisms of memory overconfidence do not directly probe personal recollections and resort instead to laboratory-based tasks and contrived rating scales. We analyzed naturalistic word use of patients with focal vmPFC damage (N = 18) and matched healthy controls (N = 23) while they recalled autobiographical memories using the Linguistic Inquiry and Word Count (LIWC) method. We found that patients with spontaneous confabulation (N = 7) tended to over-use words related to the categories of 'certainty' and of 'swearwords' compared to both non-confabulating vmPFC patients (N = 11) and control participants. Certainty related expressions among confabulating patients were at normal levels during erroneous memories and were over-expressed during accurate memories, contrary to our predictions. We found no elevation in expressions of affect (positive or negative), temporality or drive as would be predicted by some models of confabulation. Thus, erroneous memories may be associated with subjectively lower certainty, but still exceed patients' report criterion because of a global proclivity for overconfidence. This may be compounded by disinhibition reflected by elevated use of swearwords. These findings demonstrate that analysis of naturalistic expressions of memory content can illuminate global meta-mnemonic contributions to memory accuracy complementing indirect laboratory-based correlates of behavior. Memory accuracy is the result of complex interactions among multiple meta-mnemonic processes such as monitoring, report criteria, and control processes which may be shared across decision-making domains.

Fetal alcohol spectrum disorder and confabulation in psycholegal settings: A beginner's guide for criminal justice, forensic mental health, and legal interviewers

Fetal alcohol spectrum disorders (FASD) are neurodevelopmental/neurobehavioral conditions caused by prenatal alcohol exposure (PAE). Impairments caused by PAE contribute to the over-representation of individuals with FASD in the United States juvenile and adult criminal justice systems. These same impairments can equally impact on individuals with FASD who are witnesses to or victims of crime who also have to navigate the complexities of the criminal justice system. Difficulties include increased susceptibility to confabulation throughout the legal process that, in turn, can contribute to increased rates of poor outcomes including false confessions and wrongful convictions. Individuals with FASD are particularity at risk of confabulation when they are subjected to tactics, such as stressful and anxiety-provoking situations, threats, and leading, suggestive, or coercive questioning. Many professionals in the forensic context are unfamiliar with FASD or related confabulation risk and may unintentionally utilize tactics that intensify impacts of pre-existing impairment. This article serves as a beginner's guide for professionals working in criminal justice settings by (a) providing research-based overviews of FASD and confabulation, (b) describing how FASD may lead to confabulation, and (c) suggesting ways that professionals can modify protocols when interacting with individuals with FASD. Suggestions in this article hold the potential to decrease the risk of confabulation in the criminal justice system and decrease problematic outcomes, such as false confessions and wrongful convictions among individuals with FASD.

Confabulation affecting Temporal Consciousness significantly more than Knowing Consciousness

Confabulation, defined as the production of statements and actions that are unintentionally incongruous to the patient's history, background, present and future situation, is a rather infrequent memory disorder, which usually affects patients with significant memory impairment, but may be also observed in patients with normal memory and learning abilities. Confabulation may be selective affecting some cognitive, memory domains while relatively sparing others. In particular, it may affect more Temporal Consciousness, i.e. a specific form of consciousness that allows individuals to remember their personal past, to be oriented in their present world and to predict their personal future, than Knowing Consciousness, i.e. a specific form of consciousness allowing individuals to be aware of past, present and future impersonal knowledge and information. In this study we evaluated confabulations in TC and KC in a group of confabulatory amnesics of various aetiologies. Based on previous studies, it was predicted that confabulations affect significantly more TC than KC. It was also predicted that "Habits Confabulations", i.e. habits and repeated personal events mistaken as specific, unique past and future personal episodes, is the more frequently observed type of confabulation. The results confirmed these predictions and are discussed within the framework of the Memory, Consciousness and Temporality Theory.

Screening for confabulations with the confabulation screen

The objective of this work is to devise and validate a sensitive and specific test for confabulatory impairment. We conceived a screening test for confabulation, the Confabulation Screen (CS), a brief test using 10 questions of episodic memory (EM), where confabulators most frequently confabulate. It was postulated that the CS would predict confabulations not only in EM, but also in the other subordinate structures of personal temporality, namely the present and the future. Thirty confabulating amnesic patients of various aetiologies and 97 normal controls entered the study. Participants were administered the CS and the Confabulation Battery (Dalla Barba, G., & Decaix, C. (2009). "Do you remeber what you did on March 13 1985?" A case study of confabulatory hypermnesia. Cortex, 45(5), 566-574). Confabulations in the CS positively and significantly correlated with confabulations in personal temporality domains of the CB, namely EM, orientation in time and place and episodic plans. Conversely, as expected, they did not correlate with confabulations in impersonal temporality domains of the CB. Consistent with results of previous studies, the most frequently observed type of confabulation in the CS was Habits Confabulation. The CS had high construct validity and good discriminative validity in terms of sensitivity and specificity. Cut-off scores for clinical and research purposes are proposed. The CS provides efficient and valid screening for confabulatory impairment.

Behavioral evidence suggestive of frontal lobe pathology in the amnesic H.M

From the earliest published reports, Henry Gustav Molaison-who until his death in 2008 was known simply by his initials H.M.-was characterized as having a profound anterograde amnesia subsequent to mid temporal lobe resection, and that this amnestic condition was uncomplicated by other cognitive or behavioral impairments. Post-mortem neuropathological examination has detected-in addition to the expected temporal lobe lesions-previously unreported frontal lobe and white matter pathology, inviting questions concerning the behavioral and cognitive consequences that might result from such lesions. The purpose of this article is to recount published descriptions of a range of anomalous behaviors by H.M. that can not be explained by the memory impairments typically associated with anterograde amnesia, to counter previous claims that these behaviors are attributable to amygdalar damage, and to advance the interpretation that these behaviors are instead consistent with well-documented effects of frontal lobe pathology. Transcripts of interviews with H.M. which feature disjointed, often contradictory, and arguably confabulatory responses are presented in support of this argument.

Human lesion studies of ventromedial prefrontal cortex

Studies of neurological patients with focal lesions involving ventromedial prefrontal cortex (vmPFC) have demonstrated a critical role for this brain area in various aspects of cognition, emotion, and behavior. In this article, we review the key themes, methods, and findings from neuropsychological research on vmPFC lesion patients. Early case studies demonstrated profound disruptions in personality and behavior following vmPFC damage, including blunted affect, poor decision-making, and inappropriate social behavior. Subsequent laboratory investigations with groups of vmPFC lesion patients have revealed deficits in a host of interrelated functions, such as value-based decision-making, future and counterfactual thinking, physiological arousal to emotional stimuli, emotion recognition, empathy, moral judgment, and memory confabulation. The compendium of findings described here demonstrates that vmPFC is crucial for diverse aspects of adaptive function.

Confabulation: Developing the 'emotion dysregulation' hypothesis

Confabulations offer unique opportunities for establishing the neurobiological basis of delusional thinking. As regards causal factors, a review of the confabulation literature suggests that neither amnesia nor executive impairment can be the sole (or perhaps even the primary) cause of all delusional beliefs - though they may act in concert with other factors. A key perspective in the modern literature is that many delusions have an emotionally positive or 'wishful' element, that may serve to modulate or manage emotional experience. Some authors have referred to this perspective as the 'emotion dysregulation' hypothesis. In this article we review the theoretical underpinnings of this approach, and develop the idea by suggesting that the positive aspects of confabulatory states may have a role in perpetuating the imbalance between cognitive control and emotion. We draw on existing evidence from fields outside neuropsychology, to argue for three main causal factors: that positive emotions are related to more global or schematic forms of cognitive processing; that positive emotions influence the accuracy of memory recollection; and that positive emotions make people more susceptible to false memories. These findings suggest that the emotions that we want to feel (or do not want to feel) can influence the way we reconstruct past experiences and generate a sense of self - a proposition that bears on a unified theory of delusional belief states.

Medio-dorsal thalamus and confabulations: Evidence from a clinical case and combined MRI/DTI study

The Medio-Dorsal Nuclei (MDN) including the thalamic magnocellular and parvocellular thalamic regions has been implicated in verbal memory function. In a 77 year old lady, with a prior history of a clinically silent infarct of the left MDN, we observed the acute onset of spontaneous confabulations when an isolated new infarct occurred in the right MDN. The patient and five age-matched healthy subjects underwent Magnetic Resonance Imaging (MRI) and Diffusion Tensor Imaging (DTI). The thalamic lesions were localized by overlapping Morel Thalamic Atlas with structural MRI data. DTI was used to assess: i) white matter alterations (Fractional Anisotropy, FA) within fibers connecting the ischemic areas to cortex; ii) the micro-structural damage (Mean Diffusivity) within the thalamic sub-regions defined by their structural connectivity to the Anterior Cingulate Cortex (ACC) and to the temporal lobes. These target regions were chosen because their damage is considered associated with the appearance of confabulations. Thalamic lesions were localized within the parvocellular regions of the right and left MDNs. The structural connectivity study showed that the fiber tracts, connecting the bilaterally damaged thalamic regions with the frontal cortex, corresponded to the anterior thalamic radiations (ATR). FA within these tracts was significantly lower in the patient as compared to controls. Mean diffusivity within the MDNs projecting to Broadman area (BA) 24, BA25 and BA32 of ACC was significantly higher in the patient than in control group. Mean diffusivity values within the MDN projecting to temporal lobes in contrast were not different between patient and controls. Our findings suggest the involvement of bilateral MDNs projections to ACC in the genesis of confabulations and help provide clarity to the longstanding debate on the origin of confabulations.

Analyzing Confabulations in Schizophrenia and Healthy Participants

OBJECTIVES

Confabulations occur in schizophrenia and certain severe neuropsychiatric conditions, and to a lesser degree in healthy individuals. The present study used a forced confabulation paradigm to assess differences in confabulation between schizophrenia patients and healthy controls.

METHODS

Schizophrenia patients (n=60) and healthy control participants (n=19) were shown a video with missing segments, asked to fill in the gaps with speculations, and tested on their memory for the story. Cognitive functions and severity of symptoms were also evaluated.

RESULTS

Schizophrenia patients generated significantly more confabulations than healthy control participants and had a greater tendency to generate confabulations that were related to each other. Schizophrenic confabulations were positively associated with temporal context confusions and formal thought disorder, and negatively with delusions.

CONCLUSIONS

Our findings show that the schizophrenia patients generate more confabulations than healthy controls and schizophrenic confabulations are associated with positive symptoms. (JINS, 2016, 22, 911-919).

Different patterns of recollection impairment in confabulation reveal different disorders of consciousness: A multiple case study

Recollection is used to refer to the active process of setting up retrieval cues, evaluating the outcome, and systematically working toward a representation of a past experience that we find acceptable. In this study we report on three patients showing different patterns of confabulation affecting recollection and consciousness differentially. All patients confabulated in the episodic past domain. However, whereas in one patient confabulation affected only recollection of events concerning his personal past, present and future, in another patient confabulation also affected recollection of impersonal knowledge. The third patient showed an intermediate pattern of confabulation, which affected selectively the retrieval of past information, both personal and impersonal. We suggest that our results are in favor of a fractionation of processes involved in recollection underling different disorders of consciousness.

Assessment of Confabulation in Patients with Alcohol-Related Cognitive Disorders: The Nijmegen-Venray Confabulation List (NVCL-20)

OBJECTIVE

Even though the first awareness of confabulations is often based on observations, only questionnaires and structured interviews quantifying provoked confabulations are available. So far, no tools have been developed to measure spontaneous confabulation. This study describes and validates an observation scale for quantifying confabulation behavior, including spontaneous confabulations, in clinical practice.

METHOD

An observation scale consisting of 20 items was developed, the Nijmegen-Venray Confabulation List-20 (NVCL-20). This scale covers spontaneous confabulation, provoked confabulation, and memory and orientation. Professional caregivers completed the NVCL-20 for 28 Korsakoff (KS) patients and 24 cognitively impaired chronic alcoholics (ALC). Their ratings were related to the Dalla Barba Confabulation Battery (DBCB), Provoked Confabulation Test (PCT), and standard neuropsychological tests.

RESULTS

The categories of the NVCL-20 have "good" to "excellent" internal consistency and inter-rater agreement. The KS patients confabulated more (both spontaneously and provoked), and more memory and orientation problems were observed. Correlations with neuropsychological test scores showed that confabulations were associated with memory deficits, but not with intrusions or tests of executive dysfunction.

CONCLUSIONS

The NVCL-20 is the first instrument that includes items addressing spontaneous confabulation. Administration is reliable, valid and feasible in clinical practice, making it a useful addition to existing confabulating measures.

A neurophenomenological model for the role of the hippocampus in temporal consciousness. Evidence from confabulation

Confabulation, the production of statements or actions that are unintentionally incongruous to the subject's history, background, present and future situation, is a rather infrequent disorder with different aetiologies and anatomical lesions. Although they may differ in many ways, confabulations show major similarities. Their content, with some minor exceptions, is plausible and therefore indistinguishable from true memories, unless one is familiar with the patient's history, background, present and future situation. They extend through the whole individuals' temporality, including their past, present and future. Accordingly, we have proposed that rather than a mere memory disorder; confabulation reflects a distortion of Temporal Consciousness (TC), i.e., a specific form of consciousness that allows individuals to locate objects and events according to their subjective temporality. Another feature that confabulators share is that, regardless of their lesion's location, they all have a relatively preserved hippocampus (Hip), at least unilaterally. In this article, we review data showing differences and similarities among forms of confabulation. We then describe a model showing that the hippocampus is crucial both for the normal functioning of TC and as the generator of confabulations, and that different types of confabulation can be traced back to a distortion of TC resulting from damage or disconnection of brain areas directly or indirectly connected to the hippocampus. We conclude by comparing our model with other models of memory and confabulation.

Isolated prospective confabulation in Wernicke-Korsakoff syndrome: a case for reality filtering

A 57-year-old man suffered severe amnesia and disorientation, accompanied by content-specific confabulation, due to an alcoholic Wernicke-Korsakoff syndrome. For months, he was deeply concerned about a single obligation that he thought he had to respond to, but which he had already assumed 20 years previously. This monothematic, prospective confabulation was associated with failures of reality filtering as previously documented in behaviorally spontaneous confabulation and disorientation: the patient failed to suppress the interference of currently irrelevant memories and to abandon anticipations that were no longer valid (impaired extinction capacity). Magnetic resonance imaging showed damage to the mamillary bodies and the dorsomedial thalamic nucleus. Positron emission tomography (FDG-PET) showed extended orbitofrontal hypometabolism. We suggest that isolated prospective confabulation shares the core feature (acts and thoughts based on currently irrelevant memory), mechanism (failure of reality filtering), and anatomical basis (orbitofrontal dysfunction) with behaviorally spontaneous confabulations.

Spontaneous confabulation, temporal context confusion and reality monitoring: a study of three patients with anterior communicating artery aneurysms

Spontaneous confabulation involves the production of false or distorted memories, and is commonly associated with ventromedial prefrontal damage. One influential theory proposes that the critical deficit is a failure to suppress currently irrelevant memory traces that intrude into ongoing thinking (Schnider & Ptak, 1999). In this study, we report experimental investigations with three spontaneously confabulating patients aimed at exploring this account. Using Schnider and Ptak's (1999) continuous recognition paradigm, we replicated their experimental results with our patients. However, our data suggest that the critical impairment might be more generalized than a failure to suppress currently irrelevant memories. First, a temporal source monitoring task failed to show that previous memory traces intrude into the present. Second, a reality monitoring task revealed that confabulating patients had a tendency to misidentify imagined events as real, a result that cannot be explained in terms of temporal confusion. This error was specific to confabulating patients and was not shared by non-confabulating ACoA patients. Our data therefore suggest a more generalized impairment in source monitoring, not only on the basis of temporality or current relevance, but across a range of contextual domains, including information used to distinguish real memories from imaginings.

Confabulation in schizophrenia: a neuropsychological study

Confabulation has been documented in schizophrenia, but its neuropsychological correlates appear to be different from those of confabulation in neurological disease states. Forty-five schizophrenic patients and 37 controls were administered a task requiring them to recall fables. They also underwent testing with a range of memory and executive tasks. The patients with schizophrenia produced significantly more confabulations than the controls. After correcting for multiple comparisons, confabulation was not significantly associated with memory impairment, and was associated with impairment on only one of eight executive measures, the Brixton Test. Confabulation scores were also associated with impairment on two semantic memory tests. Confabulation was correlated with intrusion errors in recall, but not false positive errors in a recognition task. The findings suggest that confabulation in schizophrenia is unrelated to the episodic memory impairment seen in the disorder. However, the association with a circumscribed deficit in executive function could be consistent with a defective strategic retrieval account of confabulation similar to that of Moscovitch and co-workers, interacting with defective semantic memory.

Strategic retrieval, confabulations, and delusions: theory and data

Based on Moscovitch and Winocur's "working with memory" framework, confabulation is described as a deficit in strategic retrieval processes. The present paper suggests that only a confluence of deficits on multiple memory-related processes leads to confabulation. These are divided into three categories. Core processes that are unique to confabulation and required for its evolution include: (1) an intuitive, rapid, preconscious "feeling of rightness" monitoring, (2) an elaborate conscious "editor" monitoring, and (3) control processes that mediate the decision whether to act upon a retrieved memory. The second category is deficits on constitutional processes which are required for confabulation to occur but are not unique to it. These include the formation of erroneous memory representation, (temporal) context confusion, and deficits in retrieval cue generation. Finally, associated Features of confabulations determine the content "flavour" and frequency of confabulation but are not required for their evolution. Some associated features are magnification of normal reconstructive memory processes such as reliance on generic/schematic representations, and positivity biases in memory, whereas others are abnormal such as perseveration or source memory deficits. Data on deficits in core processes in confabulation are presented. Next, the apparent correspondences between confabulation and delusion are discussed. Considering confabulation within a strategic memory framework may help elucidate both the commonalities and differences between the two symptoms. Delusions are affected by a convergence of abnormal perception and encoding of information, associated with aberrant cognitive schema structure and disordered belief monitoring. Whereas confabulation is primarily a disorder of retrieval, mnemonic aspects of delusions can be described as primarily a disorder of input and integration of information. It is suggested that delusions might share some of the associated features of confabulation but not its core and constitutional processes. Preliminary data in support of this view are presented.

Varieties of confabulation and delusion

INTRODUCTION

Different types of confabulation or false memory can arise from brain disease. There are competing explanatory theories for the mechanisms underlying confabulation. Recent literature has attempted to relate the notion of delusion to that of confabulation.

METHOD

A brief review of the literature relating to these ideas.

RESULTS

The varieties of confabulation or false memory that can arise from brain disease are considered. The varieties of delusion and the contexts in which they arise are considered. Comparisons are made between the characteristics of spontaneous confabulation and those of delusional memory.

CONCLUSION

It is suggested that global theories purporting to account for both confabulation and delusions, in whatever circumstances they arise, can have only limited explanatory power. On the other hand, there are resemblances between confabulation and delusional memory, and the similarities and differences between these phenomena deserve further empirical investigation.

Stroke and episodic memory disorders

Memory impairments are common after stroke, and the anatomical basis for impairments may be quite variable. To determine the range of stroke-related memory impairment, we identified all case reports and group studies through the Medline database and the Science Citation Index. There is no hypothesis about memory that is unique to stroke, but there are several important facets of memory impairment after stroke: (1) Every node of the limbic system implicated in memory may be damaged by stroke but very rarely in isolation and the combination of amnesia with the associated deficits often illuminates additional aspects of memory functions. (2) Stroke produces amnesia by damage to critical convergence white matter connections of the limbic system, and stroke is the only etiology of amnesia that can delineate the entire pathway of memory and critical convergence points. (3) Stroke also impairs memory, without causing classical amnesia, by damaging brain regions responsible for cognitive processes, some modality specific and some more generally strategic, that are essential for normal learning and recall.

Confabulation in Alzheimer's disease: poor encoding and retrieval of over-learned information

Patients who confabulate retrieve personal habits, repeated events or over-learned information and mistake them for actually experienced, specific unique events. Although some hypotheses favour a disruption of frontal/executive functions operating at retrieval, the respective involvement of encoding and retrieval processes in confabulation is still controversial. The present study sought to investigate experimentally the involvement of encoding and retrieval processes and the interference of over-learned information in the confabulation of Alzheimer's disease patients. Twenty Alzheimer's disease patients and 20 normal controls encoded and retrieved unknown stories, well-known fairy tales (e.g. Snow White) and modified well-known fairy tales (e.g. Little Red Riding Hood is not eaten by the wolf) under three experimental conditions: (i) full attention at encoding and at retrieval; (ii) divided attention at encoding (i.e. performing an attention demanding secondary task) and full attention at retrieval; (iii) full attention at encoding and divided attention at retrieval. We found that confabulations in Alzheimer's disease patients were more frequent for the modified well-known fairy tales and when encoding was weakened by a concurrent secondary task (61%), compared with the other types of stories and experimental conditions. Confabulations in the modified fairy tales always consisted of elements of the original version of the fairy tale (e.g. Little Red Riding Hood is eaten by the wolf). This is the first experimental evidence showing that poor encoding and over-learned information are involved in confabulation in Alzheimer's disease.

Confabulations in episodic memory are associated with delusions in Alzheimer's disease

Although confabulations and delusions are observed in Alzheimer's disease, the relationship between the 2 has not been fully investigated. This study involved 50 patients with Alzheimer's disease and 10 healthy participants. After the patients were divided into delusional and nondelusional groups, confabulations and cognitive function were assessed. No confabulations appeared in the healthy participants, and only patients with Alzheimer's disease showed confabulations. The delusional group produced more confabulations on episodic subjects than on semantic subjects. There was a correlation between cognitive impairment and confabulations in semantic memory. These findings suggest that different mechanisms are involved in confabulations between semantic and episodic memories.

Self-enhancing confabulation: revisiting the motivational hypothesis

We report a patient who developed spontaneous confabulation following surgical clipping of an anterior communicating artery aneurysm. An autobiographical memory test was used to measure the emotional valence of the patient's self-representations in true and false memories. We found that his confabulations included significantly more positive self-representations than his true memories and that the overall valence of his confabulations was more positive than that of his true memories and than that of the memories of five healthy control participants of the same age and educational attainment. It is proposed that while cognitive dysfunction may explain how confabulations are formed, emotional factors may explain which specific confabulations are constructed.

Confabulation: Motivated reality monitoring

The study addressed the hypothesis that the content of confabulation is emotionally biased. Confabulating amnesic patients were compared with amnesic non-confabulating patients in a memory recognition experiment that manipulated the valence (pleasant, unpleasant), temporal source (past, present, future) and selection agent (self, other) of the to-be-recognised memories. The results revealed that confabulating patients were more likely than amnesic non-confabulating patients to incorrectly recognise past autobiographical events or thoughts as currently relevant memories, and this was more pronounced for pleasant compared to unpleasant events. These findings suggest that motivational factors, along with defective reality and temporality monitoring, contribute to confabulation.

What are confabulators’ memories made of? A study of subjective and objective measures of recollection in confabulation

Confabulating patients claim to remember events that had not actually happened, suggesting a vivid subjective experience of false memories. The present study was aimed at examining the nature of subjective experience of retrieval in confabulators and its relation to the objective ability to recollect qualitative aspects of the original episode. In Experiment 1, 5 confabulators, 7 non-confabulating patients, and 12 control subjects studied words under shallow and deep encoding conditions and underwent a Remember (R)/Know (K) recognition task [Tulving, E. (1985). Memory and consciousness. Canadian Psychology, 26, 1-12]. For recognized words, they additionally indicated two qualitative features of the encoding context. Whereas subjective (i.e. R responses) and objective (i.e. source) measures of recollection were associated in normal controls and non-confabulating patients, they were dissociated in confabulators. In Experiment 2, participants explained the content of their R responses. We found that confabulators' recollections mainly included autobiographical information related to test items, but not to the study encounter. We conclude that remembering states in confabulators may be linked to a deficit in inhibiting irrelevant memories triggered by test items during retrieval attempts.

Provoked confabulations in Alzheimer's disease

Confabulation in Alzheimer's disease (AD) has been the subject of limited investigation. When studied, the phenomenon has been found to share characteristics with memory distortions produced by neurologically intact individuals. Previous studies that have investigated confabulation in AD have failed to take into account the characteristics of the disease and the presence of confabulations in the retrieval of recent autobiographical memory (ABM). The aim of this study was to develop a test that could investigate the tendency to confabulate in recent autobiographical memory that was specifically created for eliciting confabulatory behaviours in patients with AD. Four experiments have been carried out. In Experiment 1, AD patients who have yet to show confabulatory behaviour were compared to elderly adults. The results revealed that AD patients produced significantly more confabulations on the new test compared to elderly adults. Experiment 2 investigated if the results of the initial experiment were due to AD patients having limited working memory capacity that would lead to difficulties in performing the test compared with elderly adults as AD patients would be in a condition of memory overload. The results showed that even when compared with the performance of elderly individuals under memory overload condition, AD patients still produced more confabulations than elderly adults. Using a correlational approach Experiments 3 and 4 revealed that a high production of provoked confabulatory answers were associated with poor scores on personal episodic memory measures but not with other measures of cognitive functioning such as working memory and/or executive function.

Mechanisms of spontaneous confabulations: a strategic retrieval account

The 'temporality' hypothesis of confabulation posits that confabulations are true memories displaced in time, while the 'strategic retrieval' hypothesis suggests a general retrieval failure of which temporal confusion is a common symptom. Four confabulating patients with rupture of an anterior communicating artery (ACoA) aneurysm, eight non-confabulating ACoA controls and 16 normal controls participated in three experiments designed to test the two hypotheses. In Experiment 1, participants were tested on two continuous recognition tasks, one requiring temporal context distinctions, previously shown to be sensitive to confabulation and another that only requires content distinctions. Both manipulations were sensitive to confabulation, but not specific to it. Temporal context and content confusions (TCCs and CCs) can be explained as failures to make fine-grained distinctions within memory. In Experiment 2, free recall of semantic narratives that require strategic retrieval but are independent of temporal context was used to induce confabulations associated with remote memory, acquired before the onset of amnesia. Confabulators produced significantly more errors. Thus, when retrieval demands are equated, confabulations can be induced in the absence of temporal confusions. Only confabulators conflated semantic content from different remote semantic narratives and introduced idiosyncratic content, suggesting that qualitatively different mechanisms are responsible for distortions due to normal memory failure and for confabulation. Lesion analyses revealed that damage to ventromedial prefrontal cortex is sufficient for temporal context errors to occur, but additional orbitofrontal damage is crucial for spontaneous confabulation. In Experiment 3, we tested whether failure in memory monitoring is crucial for confabulation. Recognition of details from semantic and autobiographical narratives was used to minimize the initiation and search components of strategic retrieval. Only confabulators made more false alarms on both tasks, endorsed even highly implausible lures related to autobiographical events and were indiscriminately confident about their choices. These findings support a strategic retrieval account of confabulation of which monitoring is a critical component. Post-retrieval monitoring has at least two components: one is early, rapid and pre-conscious and the other is conscious and elaborate. Failure of at least the former is necessary and sufficient for confabulation. Other deficits, including TCC and CC, may be required for spontaneous confabulations to arise. The confluence of different sub-components of strategic retrieval would determine the content of confabulation and exacerbate its occurrence.

Confabulation, but not executive dysfunction discriminate AD from frontotemporal dementia

We examined confabulation and performance on frontal/executive tasks in Alzheimer's disease (AD) patients and patients with a diagnosis of probable frontotemporal dementia (FTD). Twenty-two patients with probable AD, 10 patients with probable FTD and 32 normal control subjects entered the study. Executive functions were assessed with the Modified Card Sorting test; a verbal fluency test; the Cognitive Estimation test; and the Stroop test. Confabulations were assessed with a modified version of the Confabulation Battery. The Confabulation Battery included 10 questions tapping each of the following domains: Episodic Memory (memories of personal past episodes), Semantic Memory (knowledge of famous facts and famous people), and Personal Future (personal plans). The results revealed that both AD patients and FTD patients were clearly and equally impaired on tests of executive functions. Both patients' groups confabulated across the three tasks of the Confabulation Battery, but FTD patients confabulated significantly more than AD patients on Episodic Memory and Personal Future. The results failed to provide any evidence of a correlation between the performance on frontal/executive tasks and the tendency to produce confabulatory reports. According to our results, confabulation, more than a deficit of frontal/executive functions, discriminate between AD and FTD. Therefore, screening for confabulation and, possibly, for other types of memory distortions may constitute a useful additional clinical tool in order to discriminate AD from FTD.

Error detection in patients with lesions to the medial prefrontal cortex: an ERP study

When people detect their own errors in a discrimination task, a negative-going waveform can be observed in scalp-recorded EEG that has been coined the error-related negativity (Ne/ERN). Generation of the Ne/ERN has been associated with structures in the prefrontal cortex, especially the anterior cingulate region, but also the supplementary motor cortex and subcortical structures. There is some controversy as to whether the Ne/ERN is a necessary concomitant to error detection. We examined the Ne/ERN in five patients with damage to the medial prefrontal cortex, including the anterior cingulate region. Our findings support the implication of the rostral anterior cingulate in Ne/ERN production, but they also show that subjects can be aware of errors and yet not produce an Ne/ERN. Thus, error detection leads to the Ne/ERN process and damage to the anterior cingulate region may interrupt this relay, suggesting that error detection may be supported by circuits outside the anterior cingulate region.

Spontaneous confabulation, reality monitoring, and the limbic system--a review

Patients with anterior limbic damage may present a distinct syndrome, spontaneous confabulation: they fail in common memory tests, act on the basis of previous habits rather than currently relevant memories, produce confabulations composed of elements of past true events, are disorientated, and are absolutely convinced about the veracity of their perceived reality. Spontaneous confabulation is independent of other false memories, such as, provoked confabulations or illusory recognition. Studies showed that spontaneous confabulators fail to suppress (inactivate) evoked memories that do not pertain to ongoing reality. Rehabilitation differs from other memory failures. Prognosis depends on the lesion site, but recovery is always associated with recovery of this suppression capacity. Lesions typically involve the posterior medial orbitofrontal cortex or its connections in the basal forebrain. Imaging and evoked potential studies in healthy subjects support the idea that the anterior limbic system provides a reality monitoring mechanism which selects memories of current relevance by suppressing (inactivating) currently irrelevant memories. This mechanism appears to adjust the cortical representation of activated memories before their content is recognised and consolidated. Comparison with animal studies suggests that human reality monitoring is a property of the brain's reward system.

Recovery from spontaneous confabulations parallels recovery of temporal confusion in memory

BACKGROUND

In previous studies, the authors found that patients with spontaneous confabulation differ from those with nonconfabulating amnesia by 1) temporal context confusion (TCC) in memory based on an inability to suppress intrusions of currently irrelevant memory traces into ongoing thinking; and 2) lesions involving the orbitofrontal cortex, basal forebrain, or amygdala and perirhinal cortex.

OBJECTIVES

To study the long-term clinical course of spontaneous confabulations, determine whether TCC in memory also parallels the clinical course of spontaneous confabulations, and study the impact of lesion site on clinical course.

METHODS

Eight patients with spontaneous confabulation were re-examined 18 months after onset. Tests of memory and executive functioning and measurement of TCC in memory were again applied. MRI according to a standard protocol was performed to determine areas of permanent damage.

RESULTS

Seven patients eventually stopped confabulating. TCC, but not common memory or executive tests, precisely paralleled the course of spontaneous confabulations. Patients with isolated, less extensive, orbitofrontal lesions stopped confabulating first and had the best neuropsychological outcome. Patients with basal forebrain lesions continued to confabulate for several months and remained amnesic. One patient with extensive orbitofrontal damage and perirhinal cortex damage continues to confabulate after more than 3 years, continuing to confuse memory traces.

CONCLUSIONS

Temporal context confusion in memory is not only the sole feature reliably separating patients with spontaneous confabulation from those with nonconfabulating amnesia in the acute stage, it is also the only feature that precisely parallels the clinical course of spontaneous confabulations. Most patients eventually stop confabulating but duration of confabulations depends on the lesion site.

Confabulation and multiple sclerosis: a rare association

BACKGROUND

Fantastic confabulation in the context of Multiple Sclerosis (MS) has not previously been reported in the literature. The association is of interest because clearly demonstrable brain pathology in MS together with other cognitive and behavioural correlates may further our understanding of the neural basis underlying confabulation.

METHODS

A single case report with magnetic resonance imaging of the brain and detailed neuropsychological evaluation.

RESULTS

Confabulation occurred together with disinhibited and stimulus bound behaviour. While the patient's physical and emotional state limited the range of psychometric tests administered, the results revealed an inability to maintain focused, regulated information processing. Although memory difficulties were present, they were not in the nature of a severe amnesic disorder. The patient appeared to have a broad fund of knowledge, but the associations binding the information together and putting it into context were loose. All three features of a triad of responses previously described in confabulating patients were present, namely an inability to withhold answers, to monitor one's own responses and provide verbal self corrections. MRI of the brain showed bilateral periventricular lesions and discrete frontal lesions with 53% of the total lesion volume distributed in frontal areas. Cortical atrophy, most marked in frontal regions also was conspicuous.

CONCLUSIONS

Confabulation linked to frontal lobe involvement may occur as part of the changes in mentation found in MS. It is, however, rare and although associated with impaired memory, may be found in the absence of a severe amnesic disorder. This conclusion is discussed in the light of observations from the literature suggesting that frontal involvement is a prerequisite before fantastic confabulation occurs.

Spontaneous confabulators fail to suppress currently irrelevant memory traces

Human actions require integration of past experiences, ongoing percepts and future concepts. To adapt behavior to reality, the brain must identify mental representations of current relevance. Occasional amnesic subjects act according to invented stories ('spontaneous confabulations'), disregarding present reality. We used repeated runs of a continuous recognition task to measure the ability to distinguish currently relevant from previously encountered but currently irrelevant information. Spontaneous confabulators detected target items as accurately as nonconfabulating amnesics, but increasingly failed to suppress false-positive responses, confusing presentation in previous runs with presentation in the current run. Lesions involved the anterior limbic system: medial orbitofrontal cortex, basal forebrain, amygdala and perirhinal cortex or medial hypothalamus. We suggest that the anterior limbic system represents 'now' in human thinking by suppressing currently irrelevant mental associations.

Deception and detection in psychiatric diagnosis

Deception is ubiquitous in all communication and relationships. It can be conscious, unconscious, or both. It is present in all psychiatric diagnoses as alterations of history, symptom fabrication, symptom enhancement or minimization, and noncompliance with treatment recommendations. We are born better deceivers than we are detectors and untrained intuition may result in very unreliable discrimination. In order to improve our ability to distinguish fact from fiction, the diagnostician must attend to clues in the patient's history and physical and mental status examinations. Laboratory examination, psychological testing, and polygraphy also can be useful adjuncts in detection; however, the first step is always suspicion.

Temporal gradient in confabulation

We report on a patient, PL, who developed an amnesic confabulatory syndrome following heart arrest. PL's confabulation occurred both in episodic and semantic memory tasks. In a task in which she was asked to identify photographs of people and events highly familiar to her, a temporal gradient on her performance emerged. Confabulation was massive for the recognition of photographs from the eighties and decreased consistently for the recognition of photographs representing people and events from earlier decades. Correct responses, in contrast, were distributed according to an opposite pattern. Correct recognition was very high for photographs from the fifties but consistently decreased for photographs from the following decades. These results are discussed in terms of the co-occurrence and interaction of preserved awareness of the personal past and impaired ability to access less stable memories. These results also suggest that memories are not stored randomly but according to a temporal criterion that presumably reflects the relative strength and stability of stored episodic memories.

Improving orientation in head injured adults by repeated practice, multi-sensory input and peer participation

The efficacy of using antecedent control procedures (practice, multi-sensory input and peer participation) in facilitating orientation to person, place and time with two survivors of traumatic brain injuries were tested in two studies. In the first investigation, a 23-year-old male was treated by presenting the orientation questions orally while being shown questions on written flashcards. Results suggest that correct responses to orientation questions only occurred when flashcards were coupled with oral questioning. The participant responded correctly to nearly 100% of all orientation questions within 2 weeks of initiating flashcards. In the second study, a 19-year-old male was asked to respond in writing to 20 orientation questions in a small group. The group had a leader and 4 TBI patients. Following this, group members who correctly answered the orientation questions, took turns reading orientation questions and providing the correct responses.