Network Localization of Unconscious Visual Perception in Blindsight

OBJECTIVE

Blindsight is a disorder where brain injury causes loss of conscious but not unconscious visual perception. Prior studies have produced conflicting results regarding the neuroanatomical pathways involved in this unconscious perception.

METHODS

We performed a systematic literature search to identify lesion locations causing visual field loss in patients with blindsight (n = 34) and patients without blindsight (n = 35). Resting state functional connectivity between each lesion location and all other brain voxels was computed using a large connectome database (n = 1,000). Connections significantly associated with blindsight (vs no blindsight) were identified.

RESULTS

Functional connectivity between lesion locations and the ipsilesional medial pulvinar was significantly associated with blindsight (family wise error p = 0.029). No significant connectivity differences were found to other brain regions previously implicated in blindsight. This finding was independent of methods (eg, flipping lesions to the left or right) and stimulus type (moving vs static).

INTERPRETATION

Connectivity to the ipsilesional medial pulvinar best differentiates lesion locations associated with blindsight versus those without blindsight. Our results align with recent data from animal models and provide insight into the neuroanatomical substrate of unconscious visual abilities in patients. ANN NEUROL 2022;91:217-224.

The Science of Transitional States of Consciousness and Euthanasia

The science of transitional states of consciousness is reviewed. Despite intensive study, determining the subjective experience of animals during transitional states of consciousness remains inherently limited. Until better assessment tools become available, behavior-based observations, such as loss of righting reflex/loss of posture, remain among our most useful guides to the onset of unconsciousness in animals. To minimize potential animal suffering and to ensure a truly unconscious state is unambiguously achieved, a state of general anesthesia relying on gamma amino butyric acid type A agonists or N-methyl-d-aspartate antagonist agents continues to be a necessary component of the companion animal euthanasia process.

A signal detection-item response theory model for evaluating neuropsychological measures

INTRODUCTION

Models from signal detection theory are commonly used to score neuropsychological test data, especially tests of recognition memory. Here we show that certain item response theory models can be formulated as signal detection theory models, thus linking two complementary but distinct methodologies. We then use the approach to evaluate the validity (construct representation) of commonly used research measures, demonstrate the impact of conditional error on neuropsychological outcomes, and evaluate measurement bias.

METHOD

Signal detection-item response theory (SD-IRT) models were fitted to recognition memory data for words, faces, and objects. The sample consisted of U.S. Infantry Marines and Navy Corpsmen participating in the Marine Resiliency Study. Data comprised item responses to the Penn Face Memory Test (PFMT; N = 1,338), Penn Word Memory Test (PWMT; N = 1,331), and Visual Object Learning Test (VOLT; N = 1,249), and self-report of past head injury with loss of consciousness.

RESULTS

SD-IRT models adequately fitted recognition memory item data across all modalities. Error varied systematically with ability estimates, and distributions of residuals from the regression of memory discrimination onto self-report of past head injury were positively skewed towards regions of larger measurement error. Analyses of differential item functioning revealed little evidence of systematic bias by level of education.

CONCLUSIONS

SD-IRT models benefit from the measurement rigor of item response theory-which permits the modeling of item difficulty and examinee ability-and from signal detection theory-which provides an interpretive framework encompassing the experimentally validated constructs of memory discrimination and response bias. We used this approach to validate the construct representation of commonly used research measures and to demonstrate how nonoptimized item parameters can lead to erroneous conclusions when interpreting neuropsychological test data. Future work might include the development of computerized adaptive tests and integration with mixture and random-effects models.

Non-alcoholic Wernicke's encephalopathy with cortical involvement and polyneuropathy following gastrectomy

In this study, we present the clinical manifestations, brain magnetic resonance imaging (MRI) and concurrent polyneuropathies in two patients with non-alcoholic Wernicke's encephalopathy (WE) after gastrojejunostomy (Billroth II) anastomosis procedures. These patients developed sub-acute onset of disorientation and disturbance of consciousness following several weeks of poor intake. Peripheral neuropathy of varying severity was noted before and after the onset of WE. Brain MRI of the patients showed cerebellar vermis and symmetric cortical abnormalities in addition to typical WE changes. Electrophysiological studies demonstrated axonal sensorimotor polyneuropathy. Prompt thiamine supplement therapy was initiated and both patients gradually recovered, however mild amnesia was still noted 6 months later. We reviewed non- alcoholic WE with atypical cortical abnormalities in English language literatures and identified 29 more cases. Eight out of 31 (25.8%) patients died during follow-up. Nine patients with gait disturbance or motor paresis had showed hyporeflexia in neurological examinations. In addition to classic triad, seizure was recorded in seven patients. Dietary deprivation is a risk factor for non-alcoholic WE among elderly patients receiving gastrointestinal surgery. The prognosis is good after thiamine supplement therapy. Recognizing the MRI features and predisposing factors in patients who have undergone gastrectomy can aid in the diagnosis and management.

White matter abnormalities are associated with overall cognitive status in blast-related mTBI

Blast-related mild traumatic brain injury (mTBI) is a common injury of the Iraq and Afghanistan Wars. Research has suggested that blast-related mTBI is associated with chronic white matter abnormalities, which in turn are associated with impairment in neurocognitive function. However, findings are inconsistent as to which domains of cognition are affected by TBI-related white matter disruption. Recent evidence that white matter abnormalities associated with blast-related mTBI are spatially variable raises the possibility that the associated cognitive impairment is also heterogeneous. Thus, the goals of this study were to examine (1) whether mTBI-related white matter abnormalities are associated with overall cognitive status and (2) whether white matter abnormalities provide a mechanism by which mTBI influences cognition. Ninety-six Operation Enduring Freedom/Operation Iraqi Freedom (OEF/OEF) veterans were assigned to one of three groups: no-TBI, mTBI without loss of consciousness (LOC) (mTBI-LOC), and mTBI with LOC (mTBI + LOC). Participants were given a battery of neuropsychological tests that were selected for their sensitivity to mTBI. Results showed that number of white matter abnormalities was associated with the odds of having clinically significant cognitive impairment. A mediation analysis revealed that mTBI + LOC was indirectly associated with cognitive impairment through its effect on white matter integrity. These results suggest that cognitive difficulties in blast-related mTBI can be linked to injury-induced neural changes when taking into account the variability of injury as well as the heterogeneity in cognitive deficits across individuals.

Alterations in autobiographical memory for a blast event in Operation Enduring Freedom and Operation Iraqi Freedom veterans with mild traumatic brain injury

OBJECTIVE

Although loss of consciousness associated with moderate or severe traumatic brain injury (TBI) is thought to interfere with encoding of the TBI event, little is known about the effects of mild TBI (mTBI), which typically involves only transient disruption in consciousness.

METHOD

Blast-exposed Afghanistan and Iraq War veterans were asked to recall the blast event. Participants were stratified based on whether the blast was associated with probable mTBI (n = 50) or not (n = 25). Narratives were scored for organizational structure (i.e., coherence) using the Narrative Coherence Coding Scheme (Reese et al., 2011) and episodic recollection using the Autobiographical Interview Coding Procedures (Levine et al., 2002).

RESULTS

The mTBI group produced narratives that were less coherent but contained more episodic details than those of the no-TBI group.

CONCLUSION

These results suggest that mTBI interferes with the organizational quality of memory in a manner that is independent of episodic detail generation.

[Episodes of apparent transient loss of consciousness: disorders a cardiologist should not ignore]

Affections such as psychogenic (functional) pseudosyncope and cataplexy are characterized by transient attacks without impairment of consciousness, but with loss of postural control and unresponsiveness. Therefore, these disorders should be differentiated from syncope and should not be ignored by the cardiologist, who is usually a reference point for patients with syncope or suspected syncope. Clinical findings that suggest psychogenic pseudosyncope include frequent attacks always in the presence of audience, a fall to the ground that may develop slowly enough to allow the patient to stagger and break the fall before hitting the floor, prolonged attacks (>10 min), many psychosomatic symptoms as the clinical context. In most cases, the differential diagnosis should be made with neurally mediated syncope; to this end, tilt test appears to be very useful. Cataplexy is a relevant symptom of narcolepsy; the differential diagnosis between cataplexy and syncope should be made only when symptoms of narcolepsy are mild. Clinical findings that suggest cataplexy include an emotional trigger - above all if the emotion is positive -, an "unreal" fall similar to that observed in patients with psychogenic pseudosyncope, repeated attacks in a daytime, symptoms of narcolepsy as the clinical context. Since cataleptic attacks are triggered by emotion, in most cases the differential diagnosis should be made with vasovagal syncope; a positive emotion as a trigger suggests a cataleptic attack.

An existential-phenomenological approach to consciousness

The human beings are characterized as subjects. Their essence is understood as Person. A treatment which does not consider the subjective and the Person would not correspond their essence. For a feeling and autonomous being, consciousness plays a role but cannot fully correspond the being a person. This has a therapeutic impact on the treatment of unconscious patients and gives the treatment a specific access. Some instructions for the therapeutic application of the phenomenological-existential concept and the phenomenological attitude towards unconscious or brain traumatized patients are given. The role of consciousness for being human is briefly reflected from an existential perspective.

Brain injury: existential view to the restoration of the patient's contact with the self and the world

We present conceptual changes in psychological rehabilitation after severe brain injury. Traditional clinical approach reduces the person's inner life to level of consciousness, considers psychological processes only from the deficit point of view. We consider the experience of coming out of coma (non-existence) from the point of fundamental components of existence, i.e. anchoring with the world, with life, with self, with the future (Langle, 2003). In aspect of experience these components form the matrix of Patient-World and Patient-Self recovery phases. While working with BI patients, we have defined following phases: 0-phase: experiencing existence, the feeling "I exist here". The main target of psychotherapy is consolidation and reinforcement of the feeling of existence through the feeling of one's body boundaries (and extension), and finding resources for surviving. 1-phase: "be-able-to-exist-in-the world". The patient comes across reality of external world. We mean first of all the perception of the factual side of the world. 2-phase: loving life. The work is concentrated on the recovery of patient's ability to address himself and others so as to be able to experience emotions and live through his own wishes. 3-phase: restoration of patient's self-image and substantiation of own value. It means self-perception and selfrespect despite all the losses and deficits because of trauma. 4-phase: finding the sense. It is necessary to help the patient to make the existential change to avoid dependent position, don't consider himself as the victim of circumstances. This conception is used on different stages of recovery starting from severe disordered consciousness to socialization stage.

Symmetry-breaking, grouped images and multistability with transient unconsciousness

Multistability in consciousness is characterised by transient switches in which the attributes of space and time are locally absent. An extensive number of studies has attempted to describe and predict the causes and duration of such switches, and many are obviously incomplete models or wrong, but some show promise. Models have, for example, drawn on neural network theory, psychophysics, signal detection theory, Markov matrices, and Shilnikov dynamics. Levels of macro-, meso- and micro-dynamics are employed by writers and contrasted. We compare some of those models and find problems in attempting to identify their properties and causality. Discontinuities in the observed local evolution of dynamical time series may be modelled in various ways; they are observed in multistability switches, in saddle-node bifurcations, and in cusp catastrophes. Three models, involving psychophysics, rapid recurrence, and neural networks, are considered as complementing rather than competing for representation.

Traumatic brain injury among U.S. active duty military personnel and negative drinking-related consequences

This study used the 2008 Department of Defense Survey of Health Related Behaviors among Active Duty Military Personnel to determine whether traumatic brain injury (TBI) is associated with past year drinking-related consequences. The study sample included currently drinking personnel who had a combat deployment in the past year and were home for ≥6 months (N = 3,350). Negative binomial regression models were used to assess the incidence rate ratios of consequences, by TBI-level. Experiencing a TBI with a loss of consciousness for more than 20 minutes was significantly associated with consequences independent of demographics, combat exposure, posttraumatic stress disorder, and binge drinking. The study's limitations are noted.

Unresponsiveness ≠ unconsciousness

Consciousness is subjective experience. During both sleep and anesthesia, consciousness is common, evidenced by dreaming. A defining feature of dreaming is that, while conscious, we do not experience our environment; we are disconnected. Besides inducing behavioral unresponsiveness, a key goal of anesthesia is to prevent the experience of surgery (connected consciousness), by inducing either unconsciousness or disconnection of consciousness from the environment. Review of the isolated forearm technique demonstrates that consciousness, connectedness, and responsiveness uncouple during anesthesia; in clinical conditions, a median 37% of patients demonstrate connected consciousness. We describe potential neurobiological constructs that can explain this phenomenon: during light anesthesia the subcortical mechanisms subserving spontaneous behavioral responsiveness are disabled but information integration within the corticothalamic network continues to produce consciousness, and unperturbed norepinephrinergic signaling maintains connectedness. These concepts emphasize the need for developing anesthetic regimens and depth of anesthesia monitors that specifically target mechanisms of consciousness, connectedness, and responsiveness.

What is the cause of post-traumatic stress disorder following subarachnoid haemorrhage? Post-ictal events are key

BACKGROUND

Post-traumatic stress disorder (PTSD) is common after subarachnoid haemorrhage (SAH) and causes poor outcome. Knowing which SAH events cause the stress leading to PTSD development could allow for their severity, and so the chances of PTSD, to be reduced. The dramatic nature of SAH onset has meant ictal events have been the presumed cause. Frequent loss of consciousness (LOC) at ictus, and presumed resultant amnesia, however, means this might not be correct. We examined two hypotheses for how SAH patients develop PTSD despite frequent LOC. Firstly, has the frequency of amnesia for ictal events subsequent to LOC been overestimated? Secondly, is it the stress of post-ictal events, rather than ictal events, which causes PTSD?

METHOD

Sixty SAH patients, 18 months post-ictus, were assessed for PTSD, LOC at ictus, memory for ictal events, as well as which aspects of their SAH, ictal and post-ictal, were psychologically stressful. Patients also underwent neuropsychological examination.

FINDINGS

Of patients, 36.7% had PTSD. Memory overall for ictal events was more common than expected: 50% reported LOC, and only 18% reported no memory. However, memory was not associated with PTSD development. Rather, the key predictor of PTSD was the stress of post-ictal events. The stress of ictal events, cognitive impairment and clinical characteristics were unrelated to PTSD development. Post-ictal events included realizing that their life could have/had changed, that they may have been left with long-term problems, that they could have died and that they had little memory for some SAH events and regaining consciousness.

CONCLUSIONS

The traumatic quality of an SAH lies in post-ictal events, rather than ictal events. These events are related to the patients' adjustment to the experience of having had an SAH. Reducing the traumatic severity of these events could potentially reduce the likelihood of PTSD in SAH patients and so improve their outcome.

[Near-death experiences]

Near-death experiences (NDE) are lucid events that take place when a person is so physically compromised that he would die if its condition does not improve. He is unconscious, without heartbeats and breath, and with a flat-line electroencephalogram. NDE may include some of the following elements: Out of the body experiences or separation of consciousness from the physical body, increase in sensory perception and intense emotions, travel into or through a tunnel, encounter with a brilliant light and mystical beings, deceased relatives or friends, a sense of alteration in time and space, visualization of unworldly realms and a special knowledge, encounter with a barrier or boundary, and a return to the body, either voluntary or involuntary. The fact that children NDE are similar to adult NDE is an evidence that these experiences are real and not due to pre-existing beliefs, cultural influences or previous experiences in the present life. The characteristics of NDE are similar worldwide. No evidence supports the physiological, psychological, neurochemical, and neuroanatomical hypothesis proposed to explain the NDE. Multifactorial models, based on the combination of all of them (brain anoxia or hypoxia, release of serotonin, endorphins and ketamine-like compounds) have also been proposed. Although physiological, psychological, and socio-cultural factors could interact in the NDE, the hypothesis proposed consist essentially in unsupported speculations about what might be happening during the NDE.

[Paroxysmal and paroxysmal-like conditions during schizophrenia]

The clinical picture of paroxysm-like progredient schizophrenia in 104 patients was characterized by a combination of schizophrenic symptomatology, paroxismal and paroxysm-like disorders. Investigation of their psychopathological structure showed that they differ from that of epileptic paroxysms. The data obtained provide a basis for distinguishing a special variant of endogenous process and developing criteria for typological classification of paroxismal and paroxysm-like disorders.

Significance of time scale differences in psychophysics

We present modeling of both rational processes (thoughts) and emotional processes (feelings) on a two-dimensional lattice and on extremely simplified two-dimensional phase space of the brain. Our purpose is to analyze influence of differences in time-scales of various types of processes. In particular, we show that no 'central executive structure' between consciousness and unconsciousness, the existence of which was suggested by psychologists, is not needed.

A phenomenological study of medically induced unconsciousness in intensive care

Critically ill patients who require mechanical ventilation in intensive care units (ICUs) are usually sedated with drugs such as Morphine and Midazolam in order to facilitate ventilation, relieve pain and lower metabolic demands. Participants in this research were sedated to the point of 'medically induced unconsciousness' in that they were non eye opening nor responsive to verbal directives. A purposive sample of five individuals who had experienced the phenomenon of 'medically induced unconsciousness' were interviewed indepth. These interviews were transcribed verbatim and then analysed using a Husserlian phenomenological approach. Three essences were revealed within the data, each with associated themes. These essences were utter helplessness, cognition and succour. Utter helplessness was linked to: an inability to communicate either verbally or physically; pain during procedures; a sense of threat to personal safety; depersonalisation; loss of control and a sense of loneliness. Rather than an alteration of cognition, the themes that emerged within this second essence revealed attempts by participants to understand the experiences associated with 'medically induced unconsciousness'. These themes were: dreams; dissociation of self from the physical body; time-space relatedness and chaos. The final essence to emerge was that of succour. This essence portrays some of the more positive aspects of the experience. The themes revealed were: security in the ventilator; comfort in voices; human presence; painfree and purpose. Participants in this study were experiencing many things as they lay unresponsive on their beds in the ICU. The absence of physical responses should not be misinterpreted to mean that cognitive processes are not occurring. Participants appeared to be attempting to make sense of their immediate environment through their dreams.

Unconscious memory formation during anaesthesia

Do patients form memories of intra-operative events when they are adequately anaesthetized? Studies of memory priming during anaesthesia with depth or awareness monitoring provide some evidence that they do, although only the most basic form of memory function, perceptual priming, persists when patients are unconscious. The probability of memory encoding increases as depth of anaesthesia decreases. There is a theoretical possibility that patients can be adversely affected, through memory priming, by comments made in the operating theatre, and some evidence that positive intra-operative suggestions can benefit patients.

Awareness, dreaming and unconscious memory formation during anaesthesia in children

Recent studies have reported an incidence of awareness in children of around 1%, while older studies reported incidences varying from 0% to 5%. Measuring awareness in children requires techniques specifically adapted to a child's cognitive development and variations in incidence may be partly explained by the measures used. The causes and consequences of awareness in children remain poorly defined, though a consistent finding is that many children do not seem distressed by their memories. There are, however, some published reports of persistent psychological symptoms after episodes of childhood awareness. Compared to explicit memory, implicit memory is more robust in young children; however there is no evidence yet for implicit memory formation during anaesthesia in children. Children less than 3 years of age do not form explicit memory, although toddlers, infants and even neonates have signs of consciousness and implicit memory formation. In these very young children the relevance of awareness remains largely unknown.

Knowledge of Jordanian mothers with regards to emergency management of dental trauma

Studies in Jordan indicated that delay in seeking emergency management of dental trauma leads to unfavorable outcome of even mild forms of trauma. The purpose of this cross-sectional study was to assess, by means of a structured questionnaire, the level of general knowledge of mothers in Jordan with regards to the immediate emergency management of dental trauma, and its relation to socioeconomic variables. The questionnaire surveyed mothers' demographic data, basic knowledge of immediate management of tooth fracture, avulsion, and loss of consciousness. It also investigated the participants self assessed knowledge, attitude to public education, and knowledge of availability and priority of emergency services for trauma in Jordan. The sample consisted of 2215 mothers who attended mother and child care centers in the capital Amman, and in Irbid (the second largest city in Jordan) over a period of 3 months (July to September, 2003). Overall the participants' basic knowledge with regards to the emergency management of the trauma cases presented in the questionnaire was deficient regardless of age, level of education, socioeconomic class, or number of previous encounters with dental trauma. Generally, the attitude to public education on the topic was positive and chi-square test indicated that the level of education of mothers positively affected their knowledge of 'during working hour' emergency services and the importance of immediate management of dental trauma. Educational programs that can be added to the mother and child care advice protocols may help improve the knowledge and awareness of mothers and therefore improve the outcomes of dental trauma.

Interaction between Apolipoprotein epsilon 4 and traumatic brain injury in patients with Alzheimer's disease and Mild Cognitive Impairment

Several pathogenetic factors seem to contribute to the development of Alzheimer's disease (AD). Some data point to a role for traumatic brain injury (TBI), but this suggestion is not universally supported. Mayeux et al. have shown that TBI increases the risk of AD, but only through a synergistic relationship with apolipoprotein epsilon (Apo E) 4. We present the results of a cross-sectional and longitudinal study of the relationship between these factors, conducted in northern and southern Italy. We studied 337 consecutive patients with probable AD and 63 subjects with mild cognitive impairment (MCI). Information concerning head injuries was collected by interview of informants and review of medical records. Twenty-one patients with AD and 9 with MCI were found to have a history of TBI with loss of consciousness. AD and MCI patients with a history of TBI, compared with control groups matched for age, sex, education and degree of mental impairment, showed more marked depressive and behavioural disturbances (Global Deterioration Scale and Neuropsychiatric Inventory, p<0.05). Six- and 12-month follow up of both groups did not show significant differences in the rate of progression of cognitive changes. A high frequency of Apo E 4 was detected in the patients with TBI and cognitive impairment (40.5% in the AD and 11% in the MCI subgroups). The distribution of the epsilon 4 allele in our control group was 4%, comparable to that found in the Italian population. Distribution of the above parameters was similar in patients from northern and southern Italy. The higher frequency of TBI and Apo E 4 genotype among AD and MCI patients confirms the synergistic interaction of environmental and genetic factors in the development of dementia. Our data do not suggest that the presence of these two factors influences the clinical presentation or the course of the disease.

Clinical factors associated with quality of life in patients with transient loss of consciousness

INTRODUCTION

Transient loss of consciousness (TLOC) is common and can be lethal. Although the patients with the most prevalent causes of TLOC have a benign prognosis, morbidity is considerable. Aim of this article, therefore, was to compare the generic quality of life (QoL) of patients presenting with TLOC with that of the general population, to compare the disease-specific QoL with that of an American referral sample, and to examine which sociodemographic and clinical factors are associated with QoL in these patients.

METHODS

This study was part of the fainting assessment study (FAST), which assessed diagnostic strategies for adult patients presenting with TLOC to the Academic Medical Center Amsterdam, between February 2000 and May 2002. The generic short form-36 (SF-36) health survey and the disease-specific syncope functional status questionnaire (SFSQ) were used to assess QoL.

RESULTS

Of 468 included patients, 82% completed the questionnaires. Patients with TLOC scored poorer on all scales of the SF-36 than the Dutch population, with effect sizes ranging from 0.43 to 1.11 (>0.5 = moderate effect; >0.8 = large effect). The SFSQ indicated mean impairment in 33% of the listed activities (such as driving). Female gender, higher level of comorbidity, shorter duration of complaints, having had more than one syncopal episode, and the presence of presyncopal episodes were associated with poorer QoL.

CONCLUSION

TLOC seriously affects QoL, especially in patients with a recent onset of clinical symptoms and those suffering from both syncopal and presyncopal episodes.

Acute infantile encephalopathy predominantly affecting the frontal lobes

To establish a novel subtype of acute infantile encephalopathy, the clinical and radiologic features of nine infants with acute encephalopathy involving the bilateral frontal lobes were examined. These patients had convulsive status epilepticus with hyperpyrexia followed by a prolonged impairment of consciousness for 2-20 days. After the recovery of consciousness, all the patients manifested regression of verbal function and lack of spontaneity. Some of them also exhibited stereotypic movements, instability of mood, or catalepsy. Transient postictal edema in both frontal lobes was suggested by diffusion-weighted magnetic resonance imaging. Attenuated cerebral perfusion in the frontal lobes was demonstrated by single-photon emission computed tomography at the tenth day after onset or subsequently. Serial studies disclosed atrophic changes in the frontal lobes. All patients manifested regression or retardation of motor and verbal functions. The recovery of intellectual deficit was slower and less prominent than that of motor dysfunction. These unique features suggest that the frontal lobes are the focus of this novel subtype of acute encephalopathy, which we propose to call acute infantile encephalopathy predominantly affecting the frontal lobes.

Individual effect-site concentrations of propofol are similar at loss of consciousness and at awakening

Reported effect-site concentrations of propofol at loss of consciousness and recovery of consciousness vary widely. Thus, no single concentration based on a population average will prove optimal for individual patients. We therefore tested the hypothesis that individual propofol effect-site concentrations at loss and return of consciousness are similar. Propofol effect-site concentrations at loss and recovery of consciousness were estimated with a target-control infusion system in 20 adults. Propofol effect-site concentrations were gradually increased until the volunteers lost consciousness (no response to verbal stimuli); unconsciousness was maintained for 15 min, and the volunteers were then awakened. This protocol was repeated three times in each volunteer. Our major outcomes were the concentration producing unconsciousness and the relationship between the estimated effect-site concentrations at loss and recovery of consciousness. The target effect-site propofol concentration was 2.0 +/- 0.9 at loss of consciousness and 1.8 +/- 0.7 at return of consciousness (P <0.001). The average difference between individual effect-site concentrations at return and loss of consciousness was only 0.17 +/- 0.32 microg/mL (95% confidence interval for the difference 0.09-0.25 microg/mL). Our results thus suggest that individual titration to loss of consciousness is an alternative to dosing propofol on the basis of average population requirements.

Sensation seeking and risk behaviors in young adults with and without a history of head injury

Research has demonstrated a relation between sensation seeking and risky behavior as well as an association between risky behavior and the occurrence of head injury. This study assessed sensation seeking in young adults with and without a history of head injury by administration of the Sensation Seeking Scale (SSS), the Driver Risk Index (DRI), and the MacAndrews Scale of the Minnesota Multiphasic Personality Inventory (MMPI). There was a significant difference between the groups for the Thrill and Adventure Seeking Subscale of the SSS and the MacAndrews Scale of the MMPI, with head-injured participants scoring higher. Gender differences were seen in both groups for subscales of the SSS, with men scoring higher. Significant correlations were found for head-injured participants between the DRI and the Boredom Susceptiblity Subscale of the SSS, suggesting that as knowledge of risk increased for these participants, so did their preferences for risky behaviors. However, non-head-injured participants indicated a lower interest in risky behaviors as their knowledge of risk increased.

Experiential aspects of alcohol-induced blackouts among college students

Our current understanding of alcohol-induced memory blackouts is derived largely from research with middle-aged, hospitalized, male alcoholics. In the present study, 50 undergraduate students (34 female and 16 male) with a history of at least one blackout were interviewed to gain insight into their experiences. Fragmentary blackouts, in which memory for events is fragmented, were far more common than blackouts of the en bloc type, in which a period of time is simply missing from memory. Most students recalled bits and pieces of events without cueing from others, yet still relied on friends, most also intoxicated themselves during the blackout period, to tell them what transpired. Thinking about the fragments triggered further recall in the majority of cases. Half of all subjects, more females than males, reported having been frightened by their last blackout experience. Being frightened typically led to more careful drinking for several weeks or longer. Characteristics of blackouts among college students in the present study are compared to the standard model of blackouts based on reports from alcoholics.

Brain, conscious experience and the observing self

Conscious perception, like the sight of a coffee cup, seems to involve the brain identifying a stimulus. But conscious input activates more brain regions than are needed to identify coffee cups and faces. It spreads beyond sensory cortex to frontoparietal association areas, which do not serve stimulus identification as such. What is the role of those regions? Parietal cortex support the 'first person perspective' on the visual world, unconsciously framing the visual object stream. Some prefrontal areas select and interpret conscious events for executive control. Such functions can be viewed as properties of the subject, rather than the object, of experience - the 'observing self' that appears to be needed to maintain the conscious state.

A comparison of alcohol abusers who have and have not experienced blackouts

This study examined the proposition that the experience of alcoholic blackouts is related to other indices of cerebral involvement in the alcoholic process. In particular it was suggested that those who experience alcoholic blackouts would also show signs of the effects of alcoholic damage in the form of lower scores on cognitive functions vulnerable to the effects of long-term alcohol abuse. While some evidence was found linking the experience of blackout to the severity of the alcohol problem, no relationship was found between cognitive functioning and the experience of blackout. The possibility that different mechanisms may underlie the various cognitive sequelae of alcohol abuse is raised.

Predictors of postconcussion symptom complex in community dwelling male veterans

The presence of a persistent postconcussion symptom complex (PPCSC) was examined in a non-referred sample of male veterans with a history of mild head injury and a comparison group without a history of head injury. Hierarchical logistic regression procedures were used to determine possible predictors of PPCSC using variables supported by previous research (i.e., preexisting psychiatric difficulties, demographic and social support variables, and history of an accidental injurious event). Although PPCSC was common in all groups (23% of the total sample), a significantly greater proportion of individuals in the mild head injury with loss of consciousness group (37.2%) had PPCSC compared with three other groups (head injury without loss of consciousness = 26.1%; motor vehicle accident without head injury = 23%; and control = 17.3%). However, the most salient predictors of PPCSC were early life psychiatric difficulties such as anxiety or depression, limited social support, lower intelligence, and interactions among these variables. The predictive value of loss of consciousness was significant, but low (1.4% of unique variance). The findings provide support for the premise that PPCSC is mediated in part by individual resilience, preexisting psychological status, and psychosocial support.

Conscious expectation and unconscious conditioning in analgesic, motor, and hormonal placebo/nocebo responses

The placebo and nocebo effect is believed to be mediated by both cognitive and conditioning mechanisms, although little is known about their role in different circumstances. In this study, we first analyzed the effects of opposing verbal suggestions on experimental ischemic arm pain in healthy volunteers and on motor performance in Parkinsonian patients and found that verbally induced expectations of analgesia/hyperalgesia and motor improvement/worsening antagonized completely the effects of a conditioning procedure. We also measured the effects of opposing verbal suggestions on hormonal secretion and found that verbally induced expectations of increase/decrease of growth hormone (GH) and cortisol did not have any effect on the secretion of these hormones. However, if a preconditioning was performed with sumatriptan, a 5-HT(1B/1D) agonist that stimulates GH and inhibits cortisol secretion, a significant increase of GH and decrease of cortisol plasma concentrations were found after placebo administration, although opposite verbal suggestions were given. These findings indicate that verbally induced expectations have no effect on hormonal secretion, whereas they affect pain and motor performance. This suggests that placebo responses are mediated by conditioning when unconscious physiological functions such as hormonal secretion are involved, whereas they are mediated by expectation when conscious physiological processes such as pain and motor performance come into play, even though a conditioning procedure is performed.

Subjective experience of a confusional state

BACKGROUND

Confusional states associated with medical and surgical conditions require more study and biochemical explanation.

AIMS

To understand impairment of consciousness, cognition and memory.

METHOD

A psychiatrist reports experience of his changing mental state over 5 days from notes made immediately on recovery.

RESULTS

A prodromal phase of declining consciousness, understanding and memory registration over perhaps 48 h was difficult to detect. During unconsciousness there were four brief partial reversals with arousal, and some mental functioning (memory, formation of beliefs) occurred. CONCLUSIONS; Self-report can be a useful addition in clinical study, and patients with renal failure require psychological and psychiatric study. Comparison with the mental effects of benzodiazepine or of an anaesthetic such as nitrous oxide might throw light on the pathology.

Postconcussional disorder following mild to moderate traumatic brain injury: anxiety, depression, and social support as risk factors and comorbidities

Previous studies of postconcussional disorder (PCD) have utilized a dimensional approach (i.e., number and/or severity ratings of symptoms) to study postconcussional symptoms. This study used a syndromal approach (modified form of the DSM-IV criteria) for investigating risk factors for developing PCD, 3-months postinjury. The head trauma requirement was waived in order to determine specificity of symptoms to traumatic brain injury. Preliminary results from this ongoing study indicated significant risk factors including female gender, poor social support, and elevated self-reported depressive symptoms at 1-month postinjury. Comorbidities included concurrent diagnosis of major depressive disorder and/or posttraumatic stress disorder. Hispanics were significantly less likely to develop PCD than other racial/ethnic groups. PCD resulted more frequently from motor vehicle accidents and assaults. Screening tests for PCD risk factors/comorbidities performed shortly after injury (i.e., during routine follow-up clinic appointments) coupled with appropriate referrals for psychoeducational interventions and support groups may avoid prolonged loss of productivity and poor perceived quality of life in these patients.

Posttraumatic stress disorder and mild brain injury: controversies, causes and consequences

Posttraumatic stress disorder (PTSD) is an anxiety condition that often arises following a traumatic experience. It has commonly been argued that impaired consciousness associated with mild brain injury (MBI) precludes encoding of the traumatic experience, and this prevents PTSD development. This review considers the available evidence on PTSD following MBI and indicates the distinctive nature of PTSD after MBI. The review then discusses the possible mechanisms that may mediate PTSD in this population. The interaction of PTSD and postconcussive symptoms is discussed within a cognitive model that emphasizes the role of catastrophic interpretations of postconcussive symptoms. Finally, the implications of PTSD after MBI for assessment and treatment are reviewed.

Posttraumatic stress disorder and traumatic brain injury: can they co-exist?

The possibility that posttraumatic stress disorder (PTSD) can develop following traumatic brain injury (TBI) has been the subject of considerable debate. The traditional view has held that impaired consciousness that occurs with TBI precludes encoding of the traumatic experience, and this prevents subsequent reexperiencing symptoms. This paper critically reviews available, empirical studies on PTSD in TBI populations and suggests that these two conditions can co-exist. The various mechanisms that may mediate PTSD following TBI are discussed, and special attention is given to issues that recognize the distinctive features of PTSD following TBI. These processes include implicit processing, biologically mediated fear conditioning, and reconstruction of trauma memories. Finally implications for assessment, treatment, and forensic investigation of PTSD in TBI populations are, addressed. This review concludes that TBI populations provide a useful means by which the role of traumatic memories (and impaired memories) in posttraumatic adjustment can be studied.

Unconsciousness, amnesia and psychiatric symptoms following road traffic accident injury

BACKGROUND

Although road traffic accident injury is the most common cause of traumatic brain injury, little is known of the prevalence of psychiatric complications or the significance of unconsciousness and amnesia.

AIMS

To describe amnesia and unconsciousness following a road traffic accident and to determine whether they are associated with later psychological symptoms.

METHOD

Information was obtained from medical and ambulance records for 1441 consecutive attenders at an emergency department aged 17-69 who had been involved in a road traffic accident. A total of 1148 (80%) subjects completed a self-report questionnaire at baseline and were followed up at 3 months and 1 year.

RESULTS

Altogether, 1.5% suffered major head (and traumatic brain) injury and 21% suffered minor head injury. Post-traumatic stress disorder (PTSD) and anxiety and depression were more common at 3 months in those who had definitely been unconscious than in those who had not, but there were no differences at 1 year.

CONCLUSIONS

PTSD and other psychiatric complications are as common in those who were briefly unconscious as in those who were not.

[Analysis of implicit memory during propofol anesthesia]

OBJECTIVE

Consensus has not been achieved on the presence of unconscious memory of messages in general anesthesia for methodological reasons. Our objective was to apply a model of anesthesia that allows for clinical control of the level of hypnosis in order to evaluate the presence and characteristics of implicit memory in deep sedation with propofol.

PATIENTS AND METHODS

We randomly assigned 48 consecutive patients undergoing lower limb surgery to two groups. In both groups subarachnoid anesthesia was with varying doses of propofol to maintain a level of hypnosis marked by inability to respond to orders, absence of movements and spontaneous ventilation. The experimental group listened to a recording of the words "banana" and "melon" for the semantic category of fruits and "white" and "black" for colors. The control group listened to a recording of environmental operating room noise. We recorded, among other variables, anxiety and age. Upon awakening, after the presence of conscious memory had been ruled out, we investigated implicit memory by comparing the percentage of correct answers in the two groups.

RESULTS

The experimental group had a higher percentage of correct fruit names (p = 0.03). No differences were detected for colors. The youngest patients in the experimental group were correct more often about the fruits than were older members (p = 0.04) and those with greater anxiety were more often correct (p = 0.002).

CONCLUSIONS

Implicit memory is preserved under hypnosis with propofol and is more likely to be present among those who are younger or experience greater anxiety. Concrete words with object references are more easily remembered than abstract words referring to perception. The semantic load of messages is relevant.

The primary process and the unconscious: experimental evidence supporting two psychoanalytic presuppositions

The authors report on two experiments designed to test an important feature of the primary process: unconscious categorisation by attributes rather than by relations. These experiments were designed to provide support, independently of the clinical situation, for the presupposition of a psychological unconscious and for the presupposition that unconscious mentation is organised along primary-process lines. Their results were encouraging. They found that (1) unconscious similarity judgements could be made; and (2) these judgements were based on attributes (a primary-process mechanism) rather than relationships (a secondary-process mechanism). This independent evidence, obtained in controlled experimental studies supporting two fundamental psychoanalytic presuppositions, should be welcome news to psychoanalysts, given the continuing criticism from many quarters that basic psychoanalytic ideas lack independent validation. This paper begins with an overview of the primary processes with a special focus on the role of categorisation by attribute, the particular aspect of primary process explored in this study. Next a brief history of previous empirical investigations of primary process is given, following which the current experiments are presented.

[What do patients with head injuries remember about their time of hospitalization?]

Traumatic brain injured (TBI) patients with different trauma severity were analyzed about their recollection concerning the period of hospitalization. The study was carried out in the Head Injury Outpatient Clinic at the Central Institute of the FMUSP Hospital including 45 conscious patients able to sustain an interview. Most patients were male, young adults with the major cause of trauma such as traffic accidents and falls. Most patients (86%) reported unconsciousness state of different time duration in their hospitalization period and were unable to remember anything related to that period. The predominant recollection reported by the patients who never had consciousness decreased after the trauma and that ones who had it but awoke during the hospitalization were: seeing, feeling, hearing, and reacting either to sounds and procedures.

Recurrent psychogenic coma following tracheal stenosis repair

Medication, intracranial hemorrhage, infarction, infection, hypoxia, organ failure, and nutritional deficiency may cause unconsciousness following successful emergence from anesthesia. A 39-year-old woman with a history of tracheal stenosis, depression, and anxiety had complete unconsciousness on 3 separate occasions following surgical repair of her tracheal stenosis. In each case, the patient's endotracheal tube had been removed; she was alert and oriented to person, time, and place; and she was admitted to the hospital for observation. Within a few hours after the tube was removed, the patient became abruptly unconscious for periods of 36, 18, and 30 hours. Each time, the results of cardiac, pulmonary, metabolic, and neurologic examinations and radiological studies were normal. We hypothesize that the patient's apparent comas were the result of an underlying conversion disorder precipitated by unresolved psychological conflict surrounding a long history of abuse in which she was repeatedly smothered by a pillow.