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

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.

Interventions for confabulation: A systematic literature review

OBJECTIVE

Confabulations are false memories which are expressedwithout the intention to deceive and arise following brain damage or psychological dysfunction. Confabulations can become a barrier to effective neuropsychological rehabilitation and consequently, intervention is required.The current review aimed to provide a detailed evaluative account of existing interventions for confabulation and their relative effectiveness.

METHOD

The search process found 11 studies conducive with the inclusion and exclusion criteria. A methodological quality assessment was then carried out and the majority of included studies demonstrated poor methodological quality.

RESULTS

Ten types of interventions were identified and the majority of theseled to a reduction or elimination of confabulations.

CONCLUSION

Since methodological quality of many included studies was deemed unsatisfactory, further large-scale experimental research and standardised measures are necessary to adequately compare the relative effectiveness of these interventions. Further research and clinical implications are also highlighted.

Externalization Errors of Olfactory Source Monitoring in Healthy Controls-An fMRI Study

Using a combined approach of functional magnetic resonance imaging (fMRI) and noninvasive brain stimulation (transcranial direct current stimulation [tDCS]), the present study investigated source memory and its link to mental imagery in the olfactory domain, as well as in the auditory domain. Source memory refers to the knowledge of the origin of mental experiences, differentiating events that have occurred and memories of imagined events. Because of a confusion between internally generated and externally perceived information, patients that are prone to hallucinations show decreased source memory accuracy; also, vivid mental imagery can lead to similar results in healthy controls. We tested source memory following cathodal tDCS stimulation using a mental imagery task, which required participants to perceive or imagine a set of the same olfactory and auditory stimuli during fMRI. The supplementary motor area (SMA) is involved in mental imagery across different modalities and potentially linked to source memory. Therefore, we attempted to modulate participants' SMA activation before entering the scanner using tDCS to influence source memory accuracy in healthy participants. Our results showed the same source memory accuracy between the olfactory and auditory modalities with no effects of stimulation. Finally, we found SMA's subregions differentially involved in olfactory and auditory imagery, with activation of dorsal SMA correlated with auditory source memory.

Frontolimbic affective bias and false narratives from brain disease

Since the nineteenth century, clinicians and investigators have systematically evaluated the origin of delusions and psychotic thinking. One major clue to understanding the neurobiological underpinnings of delusions is the emergence of false narratives from brain disease. In addition to delusions themselves, there are a range of other false narratives not due to deliberate lying and resulting from neurological disorders, including provoked confabulations, fantastic confabulations, false memories, magical thinking, dream delusions, and "fantastic thinking". A comparison of their characteristics, similarities, and differences suggest a hypothesis: despite different sources for their false narrative experiences, such as unusual thoughts or perceptions, all false narratives from brain disease involve erroneous or mismatched "affective biases" applied to the experiences. Affective labels usually signal the sense of rightness, sense of familiarity, and the external vs. internal origin of an experience, and they can be altered by limbic neuropathology. The location and involvement of neuropathology that facilitates false narratives involves frontolimbic regions and their connections, particularly on the right. Future investigations can focus on frontolimbic mechanisms involved in the provision of the intrinsically-linked affective biases, which indicate the nature and external/internal origin of experiences.

Effectiveness of a neuropsychological treatment for confabulations after brain injury: A clinical trial with theoretical implications

Confabulators consistently generate false memories without intention to deceive and with great feelings of rightness. However, to our knowledge, there is currently no known effective treatment for them. In order to fill this gap, our aim was to design a neuropsychological treatment based on current theoretical models and test it experimentally in 20 confabulators sequentially allocated to two groups: an experimental and a control group. The experimental group received nine sessions of treatment for three weeks (three sessions per week). The sessions consisted of some brief material that participants had to learn and recall at both immediate and delayed time points. After this, patients were given feedback about their performance (errors and correct responses). Pre- and post-treatment measurements were recorded. Confabulators in the control group were included in a waiting list for three weeks, performed the pre- and post- measurements without treatment, and only then received the treatment, after which a post-treatment measurement was recorded. This applied to only half of the participants; the other half quit the study prematurely. Results showed a significant decrease in confabulations and a significant increase in correct responses in the experimental group; by contrast, patients in the control group did not improve during the waiting list period. Only control group patients who subsequently received the treatment after serving as controls improved. The effects of the treatment were generalized to patients' everyday lives, as reported by relatives, and persisted over time. This treatment seems to be effective and easy to implement and consequently of clinical interest. Moreover, it also has theoretical implications regarding the processes related to the genesis and/or maintenance of confabulations. In particular, results point to a deficit in early stages of memory retrieval with the preservation of later strategic monitoring processes. Specifically, some of the processes involved may include selective attention or early conflict detection deficits. Future research should test these hypotheses.

Self-representation in delusional misidentification and confabulated "others"

In some instances the ostensibly false narratives produced by patients with delusional misidentification syndromes (DMS) or confabulation may - unbeknownst to the patient - contain some authentic self-referential information. In this review, extracted from a video library or verbatim transcripts of approximately 50 clinical cases with either delusional misidentification or some variety of confabulation, we identified four cases (Feinberg, 2001, 2009, 2010; Feinberg & Shapiro, 1989) with either DMS for persons or confabulations about "phantom" persons, who showed prominent "self-referential" (SR) narratives. The presence of self-referential narratives was judged by: 1) the misidentification or confabulation was generally consistent and repeatable, e.g., the narrative was repeated on more than one occasion and not variably "provoked," 2) the content of the delusional misidentifications or confabulations were facts, feelings, or motivations that were true of the patients themselves either by history obtained from collateral sources (medical records, family, friends, etc.) or by admission by the patients themselves, but were attributed to a "double" of confabulated person, 3) these facts or feelings attributed to the "double" or confabulated "other" were either denied by the patients or admitted but also attributed to the "other." For purposes of comparison we also selected from the original group of 50 patients four "comparison" cases with delusional misidentification for persons and/or confabulation who based on these same criteria for self-referential material, were judged not to show self-referential (SR) aspects (Comparison cases 1-4). The neuroanatomy and neurocognitive features of these cases are reviewed and compared, the possible role of psychological defense in the self-referential cases is considered, and a model that integrates the neuroanatomical, neuropsychological and dynamic psychological aspects of these self-related disorders is offered. We propose that an appreciation of these self-related productions could have significant clinical and therapeutic implications.

Monitoring what is real: The effects of modality and action on accuracy and type of reality monitoring error

Reality monitoring refers to processes involved in distinguishing internally generated information from information presented in the external world, an activity thought to be based, in part, on assessment of activated features such as the amount and type of cognitive operations and perceptual content. Impairment in reality monitoring has been implicated in symptoms of mental illness and associated more widely with the occurrence of anomalous perceptions as well as false memories and beliefs. In the present experiment, the cognitive mechanisms of reality monitoring were probed in healthy individuals using a task that investigated the effects of stimulus modality (auditory vs visual) and the type of action undertaken during encoding (thought vs speech) on subsequent source memory. There was reduced source accuracy for auditory stimuli compared with visual, and when encoding was accompanied by thought as opposed to speech, and a greater rate of externalization than internalization errors that was stable across factors. Interpreted within the source monitoring framework (Johnson, Hashtroudi, & Lindsay, 1993), the results are consistent with the greater prevalence of clinically observed auditory than visual reality discrimination failures. The significance of these findings is discussed in light of theories of hallucinations, delusions and confabulation.

Confabulations in schizophrenia

INTRODUCTION

Current theories of confabulation are based primarily on the observation of neurological patients. The present paper evaluates these theories based on evidence from schizophrenia. Schizophrenia is unique in that it presents with a pathophysiology which differs from that of other neuropsychiatric conditions, and yet the candidate's deficits that various theories of confabulation implicate are often simultaneously present in schizophrenia.

METHODS

A selective review of literature on schizophrenic and neurological confabulations was undertaken.

RESULTS

Schizophrenic confabulation differs from neurological confabulation in terms of its characteristic features and association with symptoms, cognition and linguistic functions. Current evidence also suggests that confabulation may be conceptualized as a special class of delusions pertaining to memory phenomena.

CONCLUSIONS

Schizophrenia presents with confabulations that cannot be fully accounted for by the existing theories. It also presents with confabulations with unique features, which have different cognitive correlates and relation to other symptoms of the condition.

A hypnotic analogue of clinical confabulation

Confabulation-fabricated or distorted memories about oneself-occurs in many disorders, but there is no reliable technique for investigating it in the laboratory. The authors used hypnosis to model clinical confabulation by giving subjects a suggestion for either (a) amnesia for everything that had happened since they started university, (b) amnesia for university plus an instruction to fill in memory gaps, or (c) confusion about the temporal order of university events. They then indexed different types of memory on a confabulation battery. The amnesia suggestion produced the most confabulation, especially for personal semantic information. Notably, subjects confabulated by making temporal confusions. The authors discuss the theoretical implications of this first attempt to model clinical confabulation and the potential utility of such analogues.

Dreams, reality and memory: confabulations in lucid dreamers implicate reality-monitoring dysfunction in dream consciousness

INTRODUCTION

Dreams might represent a window on altered states of consciousness with relevance to psychotic experiences, where reality monitoring is impaired. We examined reality monitoring in healthy, non-psychotic individuals with varying degrees of dream awareness using a task designed to assess confabulatory memory errors - a confusion regarding reality whereby information from the past feels falsely familiar and does not constrain current perception appropriately. Confabulatory errors are common following damage to the ventromedial prefrontal cortex (vmPFC). Ventromedial function has previously been implicated in dreaming and dream awareness.

METHODS

In a hospital research setting, physically and mentally healthy individuals with high (n = 18) and low (n = 13) self-reported dream awareness completed a computerised cognitive task that involved reality monitoring based on familiarity across a series of task runs.

RESULTS

Signal detection theory analysis revealed a more liberal acceptance bias in those with high dream awareness, consistent with the notion of overlap in the perception of dreams, imagination and reality.

CONCLUSIONS

We discuss the implications of these results for models of reality monitoring and psychosis with a particular focus on the role of vmPFC in default-mode brain function, model-based reinforcement learning and the phenomenology of dreaming and waking consciousness.

Implausible future events in a confabulating patient with an anterior communicating artery aneurysm

Patient MW, a known confabulator, and healthy age-matched controls produced past and future events. Events were judged on emotional valence and plausibility characteristics. No differences in valence were found between MW and controls, although a positive emotional bias toward the future was observed. Strikingly, MW produced confabulations about future events that were significantly more implausible than those produced by healthy controls whereas MW and healthy controls produced past events comparable in plausibility. A neurocognitive explanation is offered based on differences between remembering and imagining. Possible implications of this single case in relation to confabulation and mental time travel are discussed.

An overview of the neuro-cognitive processes involved in the encoding, consolidation, and retrieval of true and false memories

Perception and memory are imperfect reconstructions of reality. These reconstructions are prone to be influenced by several factors, which may result in false memories. A false memory is the recollection of an event, or details of an episode, that did not actually occur. Memory formation comprises at least three different sub-processes: encoding, consolidation and the retrieval of the learned material. All of these sub-processes are vulnerable for specific errors and consequently may result in false memories. Whereas, processes like imagery, self-referential encoding or spreading activation can lead to the formation of false memories at encoding, semantic generalization during sleep and updating processes due to misleading post event information, in particular, are relevant at the consolidation stage. Finally at the retrieval stage, monitoring processes, which are assumed to be essential to reject false memories, are of specific importance. Different neuro-cognitive processes have been linked to the formation of true and false memories. Most consistently the medial temporal lobe and the medial and lateral prefrontal cortex have been reported with regard to the formation of true and false memories. Despite the fact that all phases entailing memory formation, consolidation of stored information and retrieval processes, are relevant for the forming of false memories, most studies focused on either memory encoding or retrieval. Thus, future studies should try to integrate data from all phases to give a more comprehensive view on systematic memory distortions. An initial outline is developed within this review to connect the different memory stages and research strategies.