Metacognitive control over false memories: A key determinant of delusional thinking

This article reviews the current literature on false memories in schizophrenia. Increasing evidence suggests that neither memory impairment in general nor false memories in particular can reliably differentiate patients with schizophrenia or delusions from psychiatric controls. In contrast, it is proposed that a reduced metacognitive awareness of one’s own fallibility, and overconfidence in errors, may predispose a person to fixed, false beliefs (ie, delusions). Congruent with this position, a number of recent investigations suggest that the memory of patients with schizophrenia, as well as healthy subjects scoring high on delusional ideation, is corrupted by an increased number of incorrect memories held with high confidence, possibly relating to a jumping-to-conclusions or liberal acceptance bias in schizophrenia spectrum disorders. A new training approach is described that is intended to sharpen patients’ awareness of such errors and reduce confidence in fallible memories. Some empirical gaps and directions for further research are outlined. Delusional Thinking     

How we remember the stuff that dreams are made of: neurobiological approaches to the brain mechanisms of dream recall

Intrinsic and historical weaknesses delayed the spread of a sound neurobiological investigation on dreaming. Nevertheless, recent independent findings confirm the hypothesis that the neurophysiological mechanisms of encoding and recall of episodic memories are largely comparable across wakefulness and sleep. Brain lesion and neuroimaging studies converge in indicating that temporo-parieto-occipital junction and ventromesial prefrontal cortex play a crucial role in dream recall. Morphoanatomical measurements disclose some direct relations between volumetric and ultrastructural measures of the hippocampus-amygdala on the one hand, and some specific qualitative features of dreaming on the other. Intracranial recordings of epileptic patients also provide support for the notion that hippocampal nuclei mediate memory formation during sleep as well as in wakefulness. Finally, surface EEG studies showed that sleep cortical oscillations associated to a successful dream recall are the same involved in encoding and recall of episodic memories during wakefulness.Although preliminary, these converging pieces of evidence strengthen the general view that the neurophysiological mechanisms underlying episodic/declarative memory formation may be the same across different states of consciousness.     

Corollary discharge dysfunction in schizophrenia: evidence for an elemental deficit.

Evidence is accumulating that schizophrenia is characterized by dysfunction of efference copy/corollary discharge mechanisms that normally allow us to unconsciously recognize and disregard sensations resulting from our own actions. This dysfunction may give rise to subtle but pervasive sensory/perceptual aberrations in schizophrenic patients, altering their experience of their own overt and covert actions, as well as their interactions with the environment. It may also contribute to symptoms such as hallucinations and delusions, and may disrupt the motivation to engage with people and in activities. We developed neurophysiological paradigms to study motor-sensory feed-forward processes, or efference copy/corollary discharge mechanisms, in the speech-auditory system, and showed these processes to be deficient in chronic schizophrenia. Specifically, we observed neural responses during talking that made evident the suppressive consequences of a successful corollary discharge mechanism. We also observed synchronous neural activity preceding talking that we believe reflects the efference copy in action. Recently, we extended this neurophysiological research to the somatosensory system, again finding evidence of deficient motor-sensory feed-forward processes in schizophrenia. If dysfunction of this elemental mechanism is reliable, valid, and not the result of antipsychotic medications, it might represent a major new class of electrophysiological measures sensitive to a fundamental and ubiquitous pathophysiological process in schizophrenia.     

The brain as a dream state generator: an activation-synthesis hypothesis of the dream process.

Recent research in the neurobiology of dreaming sleep provides new evidence for possible structural and functional substrates of formal aspects of the dream process. The data suggest that dreaming sleep is physiologically determined and shaped by a brain stem neuronal mechanism that can be modeled physiologically and mathematically. Formal features of the generator processes with strong implications for dream theory include periodicity and automaticity of forebrain activation, suggesting a preprogrammed neural basis for dream mentation in sleep; intense and sporadic activation of brain stem sensorimotor circuits including reticular, oculomotor, and vestibular neurons, possibly determining spatiotemporal aspects of dream imagery; and shifts in transmitter ratios, possibly accounting for dream amnesia. The authors suggest that the automatically activated forebrain synthesizes the dream by comparing information generated in specific brain stem circuits with information stored in memory.     

Differential modulation of a common memory retrieval network revealed by positron emission tomography

Functional neuroimaging is uniquely placed to examine the dynamic nature of normal human memory, the distributed brain networks that support it, and how they are modulated. Memory has traditionally been classified into context-specific memories personally experienced ("episodic memory") and impersonal non-context-specific memories ("semantic memory"). However, we suggest that another useful distinction is whether events are personally relevant or not. Typically the factors of personal relevance and temporal context are confounded, and it is as yet not clear the precise influence of either on how memories are stored or retrieved. Here we focus on the retrieval of real-world memories unconfounding personal relevance and temporal context during positron emission tomography (PET) scanning. Memories differed along two dimensions: They were personally relevant (or not) and had temporal specificity (or not). Recollection of each of the resultant four memory subtypes-autobiographical events, public events, autobiographical facts, and general knowledge-was associated with activation of a common network of brain regions. Within this system, however, enhanced activity was observed for retrieval of personally relevant, time-specific memories in left hippocampus, medial prefrontal cortex, and left temporal pole. Bilateral temporoparietal junctions were activated preferentially for personal memories, regardless of time specificity. Finally, left parahippocampal gyrus, left anterolateral temporal cortex, and posterior cingulate cortex were involved in memory retrieval irrespective of person or time. Our findings suggest that specializations in memory retrieval result from associations between subsets of regions within a common network. We believe that these findings throw new light on an old debate surrounding episodic and declarative theories of memory and the precise involvement of the hippocampus.     

Awareness of action in schizophrenia

An abnormal sense of agency is among the most characteristic yet perplexing positive symptoms of schizophrenia. Schizophrenics may either attribute the consequences of their own actions to the intentions of others (delusions of influence), or may perceive themselves as causing events which they do not in fact control (megalomania). Previous reports have often described inaccurate agency judgements in schizophrenia, but have not identified the disordered neural mechanisms or psychological processes underlying these judgements. We report the perceived time of a voluntary action and its consequence in eight schizophrenic patients and matched controls. The patients showed an unusually strong binding effect between actions and consequences. Specifically, the temporal interval between action and consequence appeared shorter for patients than for controls. Patients may overassociate their actions with subsequent events, experiencing their actions as having unusual causal efficacy. Disorders of agency may reflect an underlying abnormality in the experience of voluntary action.     

Anxiety and hostility in the manifest dreams of schizophrenic patients

Aside from delusions, hallucinations, and thought disorders, affective disturbances belong to the most prominent symptoms of the schizophrenic process. However, nearly no empirical work has been done on the systematic investigation of the dream affects of patients with schizophrenia. We compared 96 dreams of 19 patients with schizophrenia and an equal number of dreams of 19 healthy controls collected over an 8-week period by means of the Gottschalk-Gleser Analysis Scales. Additionally, central psychopathological syndromes were measured by means of the AMDP-scales each day a patient reported a dream. Although cluster analyses showed general similarities in the organization of dream affects in the two groups, we found differences between patient and control groups in the frequency and intensity of anxious and hostile affects. As in delusions of persecution, patients experience themselves in their dreams more frequently as victims of hostility from outside, which corresponds well with a significantly higher intensity of threat anxieties (death, mutilation). On the other hand, value anxieties (guilt and separation) are found less frequently in the dreams of patients with schizophrenia pointing, together with a less differentiated organization of the dream affects, to the typical affective flattening of residual syndromes.     

Psychopathological and neuropsychological correlates of source monitoring impairment in schizophrenia

Schizophrenic patients are known to show a deficit in the source monitoring function, which refers to the set of processes involved in the attribution of an origin to memories and beliefs. A failure in source monitoring was found to be associated with Schneiderian delusions in the recent literature. This study aimed to explore in a sample of schizophrenic patients and controls two aspects of the source monitoring process-recognition and source attribution- and their possible correlation with psychopathology and basic neuropsychological performances. A group of 45 stabilized schizophrenic patients and 54 normal volunteers were studied with a Source Monitoring Task and a battery of neurocognitive functions known to be disturbed in schizophrenia. Recognition of self-generated items was significantly worse than control values in Schneiderian delusional patients only, while source attribution of recognized self-generated items was significantly biased towards the external sources in all delusional patients in comparison to controls. Among schizophrenic patients, source misattribution of self-generated items was significantly correlated to an executive, planning performance. Both performances were correlated to verbal memory in controls. Results confirm an impairment of different subcomponents of source monitoring performance in schizophrenia, heterogeneously related to psychopathological features and neuropsychological performances known to be impaired in schizophrenia.     

A comparison of dream content in laboratory dream reports of schizophrenic and depressive patient groups

We have been attracted to studying the dream for two different but interrelated reasons. In the usual clinical tradition, we have been drawn to study the dream for the insights it may provide into the personality of the dreamer. From a more theoretical point of view, we have been interested in the psychology of dreaming, especially in searching for evidence of a possible function that dreaming serves.We have pursued a series of studies of dream reports of schizophrenic and depressed patients both for the contribution they could make to our understanding of the personality of the dreamer and to elucidate possible functions of the dream. In a study of the spontaneously recalled dream reports of depressed, schizophrenic, and medical patients, we were able to distinguish among them based on the systematic analysis of the content of their dream reports.¹ The content differences, such as the most frequent character in the depressed being a family member, in the schizophrenic a stranger, and in the medical patient a friend, did indeed provide potentially valuable insights into the personality of the dreamer. In our studies of collected dream reports (REM dreams from the laboratory) of schizophrenic² and depressed patients³ before treatment and after significant improvement, we were able to show content differences which suggested that the collected dream report was reflective of the current emotional state of the patient. This supports the possibility that the dream may play some adaptational role in the psychic economy of the patient.The current report, which compares the content of REM-dream reports of depressed and schizophrenic patients, addresses itself both to the clinical problem, i.e., the light that dream reports may shed on the personality of depressed and schizophrenic patients, and to the psychology of dreaming, i.e., the possible functional significance of the dream.     

The dream as a model for psychosis: an experimental approach using bizarreness as a cognitive marker

Many previous observers have reported some qualitative similarities between the normal mental state of dreaming and the abnormal mental state of psychosis. Recent psychological, tomographic, electrophysiological, and neurochemical data appear to confirm the functional similarities between these 2 states. In this study, the hypothesis of the dreaming brain as a neurobiological model for psychosis was tested by focusing on cognitive bizarreness, a distinctive property of the dreaming mental state defined by discontinuities and incongruities in the dream plot, thoughts, and feelings. Cognitive bizarreness was measured in written reports of dreams and in verbal reports of waking fantasies in 30 schizophrenics and 30 normal controls. Seven pictures of the Thematic Apperception Test (TAT) were administered as a stimulus to elicit waking fantasies, and all participating subjects were asked to record their dreams upon awakening. A total of 420 waking fantasies plus 244 dream reports were collected to quantify the bizarreness features in the dream and waking state of both subject groups. Two-way analysis of covariance for repeated measures showed that cognitive bizarreness was significantly lower in the TAT stories of normal subjects than in those of schizophrenics and in the dream reports of both groups. The differences between the 2 groups indicated that, under experimental conditions, the waking cognition of schizophrenic subjects shares a common degree of formal cognitive bizarreness with the dream reports of both normal controls and schizophrenics. Though very preliminary, these results support the hypothesis that the dreaming brain could be a useful experimental model for psychosis.     

Dreams recall and auditory evoked potentials during propofol anaesthesia

It is unclear whether shorter wave latencies of middle-latency-auditory-evoked-potentials may be associated to cognitive function other than nondeclarative memory. We investigated the presence of declarative, nondeclarative and dreaming memory in propofol-anaesthetized patients and any relationship to intraoperatively registered middle-latency-auditory-evoked-potentials. An audiotape containing one of two stories was presented to patients during anaesthesia. Patients were interviewed on dream recall immediately upon emergence from anaesthesia. Declarative and nondeclarative memories for intraoperative listening were assessed 24 h after awakening without pointing out positive findings. Six patients who reported dream recall showed an intraoperative Pa latency less than that of patients who were unable to remember any dreams (P<0.001). A high responsiveness degree of primary cortex was associated to dream recall formation during anaesthesia.     

Pathogenesis and symptomatology of hallucinations (delusions) of organic brain disorder and schizophrenia

In this review article, in order to explore the mechanisms underlying the hallucinations/delusions of schizophrenia, we discuss the contribution of the following four questions: (i) can an understanding of dreams contribute to our understanding of the genesis of halluciations and/or delusions; (ii) are the mechanisms underlying psychotropic drug‐induced psychoses the same as those underlying the hallucinations and/or delusions in schizophrenia; (iii) does disturbed consciousness contribute to the manifestation of psychotic features; and (iv) are the psychoses caused by organic brain disorders any different to the hallucinations and/or delusions seen in schizophrenia? We conclude that there is a strong association between drug‐induced hallucinations or hallucinations associated with organic brain disorders and simple hallucinosis or fluctuations in arousal level. Because intermediate configurations and/or cross‐staining phenomena exist for hallucinations and delusions, especially in schizophrenic disorders, it is difficult to isolate the hallucinations and to recognize them as being abnormal experiences.     

Recovery of early memories associated with reported dream imagery

In recent years dreaming has been characterized as an information-processing activity that functions adaptively to match new experience with representations of past events already stored in long-term memory. Nine patients who reported dreams in psychotherapy were asked expressly if the dream imagery recalled a specific event from early in their lives. Of 50 consecutively reported dreams, 46 were associated with early events whose imagery appeared in the dream. When questioning about the past was omitted in a later series of 34 dreams, the same patients spontaneously recalled early events represented in the dream imagery only 13 times.     

The influence of emotional distraction on verbal working memory: an fMRI investigation comparing individuals with schizophrenia and healthy adults

The ability to maintain information over short periods of time (i.e., working memory) is critically important in a variety of cognitive functions including language, planning, and decision-making. Recent functional Magnetic Resonance Imaging (fMRI) research with healthy adults has shown that brain activations evoked during the delay interval of working memory tasks can be reduced by the presentation of distracting emotional events, suggesting that emotional events may take working-memory processes momentarily offline. Both executive function and emotional processing are disrupted in schizophrenia, and here we sought to elucidate the effect of emotional distraction upon brain activity in schizophrenic and healthy adults performing a verbal working memory task. During the delay period between the memoranda and memory probe items, emotional and neutral distractors differentially influenced brain activity in these groups. In healthy adults, the hemodynamic response from posterior cingulate, orbital frontal cortex, and the parietal lobe strongly differentiated emotional from neutral distractors. In striking contrast, schizophrenic adults showed no significant differences in brain activation when processing emotional and neutral distractors. Moreover, the influence of emotional distractors extended into the memory probe period in healthy, but not schizophrenic, adults. The results suggest that although emotional items are highly salient for healthy adults, emotional items are no more distracting than neutral ones to individuals with schizophrenia.     

Failure of neural responses to safety cues in schizophrenia

CONTEXT Abnormalities in associative memory processes, such as Pavlovian fear conditioning and extinction, have been observed in schizophrenia. The retrieval of fear extinction memories (safety signals) may be particularly affected; although schizophrenic patients can extinguish conditioned fear, they show a deficit in retrieving fear extinction memories after a delay. The neurobiological basis of this abnormality is unknown, but clues have emerged from studies in rodents and humans demonstrating that the ventromedial prefrontal cortex (vmPFC) is a key mediator of extinction memory retrieval. OBJECTIVE To measure autonomic and neural responses during the acquisition and extinction of conditioned fear and the delayed recall of fear and extinction memories in patients with schizophrenia and healthy control participants. DESIGN Cross-sectional case control, functional magnetic resonance imaging study. SETTING Academic medical center. PARTICIPANTS Twenty schizophrenic patients and 17 healthy control participants demographically matched to the patient group. MAIN OUTCOME MEASURES Skin conductance and blood oxygen level-dependent responses. RESULTS During fear conditioning, schizophrenic patients showed blunted autonomic responses and abnormal blood oxygen level-dependent responses, relative to control participants, within the posterior cingulate gyrus, hippocampus, and other regions. Several of these abnormalities were linked to negative symptoms. During extinction learning, patients with schizophrenia and control participants showed comparable autonomic and neural responses. Twenty-four hours after the learning phases, the control subjects exhibited decreased fear and increased vmPFC responses in the extinction (safe) context as expected, indicating successful retention of the extinction memory. In contrast, the schizophrenic patients showed inappropriately elevated fear and poor vmPFC responses in the safe context. CONCLUSION Failure of extinction memory retrieval in schizophrenia is associated with vmPFC dysfunction. In future studies, abnormalities in fear learning and extinction recall may serve as quantitative phenotypes that can be linked to genetic, symptom, or outcome profiles in schizophrenia and those at risk for the disorder.     

Impaired semantic memory in the formation and maintenance of delusions post-traumatic brain injury: a new cognitive model of delusions

This paper proposes a new cognitive model to explain the aetiology of delusions irrespective of diagnosis and/or phenomenology. The model hypothesises the influence of two processes in the formation and maintenance of delusions; (i) impaired perceptual abilities, particularly affect perception, which fosters the encoding of (ii) idiosyncratic semantic memories, especially those with an affective/self-referential valence. Previous research has established that schizophrenia patients with delusions have impaired semantic memory function. In the current paper we sought to provide evidence for (ii) abnormal semantic processing in persons with delusions with an alternative aetiology. Performance of four cases with a significant delusion post a traumatic brain injury was examined on a broad range of semantic memory tests. Overall semantic processing was impaired in the four cases relative to a normative healthy control sample. Cases performed better on tasks which required categorical identification, relative to the novel production of semantic information, which was poor in all four of the cases. These data offer preliminary evidence for our hypothesis of impaired semantic processing in persons with delusions. Findings will need to be empirically verified in larger sample groups and in those with alternative aetiologies.     

Late-onset schizophrenia. Studying clinical validity

The authors compared clinical characteristics of 36 late-onset schizophrenic patients from four centers (hospitals in San Diego, Baltimore, Los Angeles, and Montreal). There was a preponderance of the paranoid type with bizarre delusions and auditory hallucinations, chronic course of illness, and response to relatively low doses of neuroleptics. A comparison of late-onset and younger schizophrenic patients revealed both similarities and differences between the two groups. The authors reviewed the relevant literature and discussed the implications for assessing the validity of the concept of late-onset schizophrenia. They believe that, although less common, late-onset schizophrenia is probably as valid an entity (or group of entities) as schizophrenia with onset before age 45.     

Shostakovich’s Seventh Symphony

We are here together to honor the memory of Dr. Frieda Fromm-Reichmann, to try to assure that the vast good she did in her lifetime continues to live after her. Frieda was an extraordinary and memorable person. Among my many cherished memories of her is an indelible image of her climbing the podium steps carrying her notes and several pictures almost larger than herself. These were to illustrate her lectures in a course she called “The Assets of the Mentally Handicapped.” They included, for instance, prints of paintings by van Gogh. A principal purpose of this course was to present her staunch conviction that it was a grievous error to view severe mental illness, particularly schizophrenia, only as a loss, defect, or deficiency of mind as suggested by the earlier diagnostic term dementia praecox. She contended with great cogency that it was not simply a matter of the schizophrenic person's lacking normal mental capacities but that he often possessed qualities of mind not available to the so-called normal, average person. She pointed to the schizophrenic person's special sensitivity to nuances of meaning, his freedom to deviate from conventional stereotyped views of reality, and his openness to new perceptions of similarities and connections overlooked by others. She emphasized a striving to discover and to create fresh patterns of meaning.     

Bizarre delusions and DSM-III-R schizophrenia.

OBJECTIVE: Bizarre delusions are assigned greater weight relative to other delusions in the DSM-III-R diagnosis of schizophrenia. The decision to emphasize bizarre delusions was based largely on historical tradition rather than empirical evidence. This study examined 1) the extent to which a history of bizarre delusions contributes to the diagnosis of schizophrenia and 2) whether schizophrenic patients with bizarre delusions constitute a clinically distinguishable subgroup. METHOD: Two hundred fourteen consecutively admitted psychotic inpatients were assessed for bizarre delusions according to the DSM-III-R criteria. Clinical and demographic correlates of bizarre delusions were examined in subsets of patients diagnosed as schizophrenic according to DSM-III-R who also received CT scans and neuropsychological testing. RESULTS: With the base prevalence rate for schizophrenia of 0.71, bizarre delusions had a sensitivity of 0.79, a specificity of 0.56, and a positive predictive power of 0.82 for the diagnosis of schizophrenia (N = 152) relative to other psychotic disorders (N = 62). Clinical, neurobehavioral, CT scan, and premorbid adjustment data on the schizophrenic patients indicated that beyond manifesting more severe positive symptoms, patients with bizarre delusions did not otherwise constitute a clinically distinguishable subgroup. CONCLUSIONS: The data suggest that criterion A for the diagnosis of schizophrenia in DSM-IV could be improved by removing the special emphasis that was placed on bizarre delusions in DSM-III-R.     

Epileptic schizophrenia: clinical features and outcome

The aim of this study was to investigate the clinical characteristics and outcome of epileptic schizophrenia. A total of 106 patients with combined diagnoses of epilepsy and psychiatric disorder were identified; 20 were excluded and 70 agreed to participate. They were interviewed using the Schizophrenia and Affective Disorders Schedule - Lifetime Version and psychiatric diagnoses were assigned based on Research Diagnostic Criteria. Thirty-two subjects with additional diagnosis of schizophrenia were identified and compared with 31 functional schizophrenic patients matched for age. Both groups shared third person auditory hallucinations most in common, and delusions of passivity least; delusions of passivity occurred significantly more in functional schizophrenia. The global outcome was worse in epileptic schizophrenia and there was also evidence of significantly worse performance on the Mini-Mental State Examination by the same group.