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PubMed2005

Using source cues and familiarity cues to resist imagination inflation.

To investigate whether people can resist imagination inflation--the imagination-induced increased confidence that fictitious childhood events really happened--we gave them different types of cues. In a three-stage procedure, participants: (1) rated their confidence that a list of childhood events had happened to them, (2) imagined some of these events, and (3) made confidence ratings a second time. Subjects received either no cues about the source of the imagined event, an additional source cue (perspective), an additional familiarity cue (a plausibility questionnaire), or both cues. Only subjects who had both types of cues resisted imagination inflation. These results suggest that additional cues can sometimes safeguard people from becoming more confident that fictitious events were genuine experiences.

Adult↗

PubMed2006

Angiotensin-converting enzyme inhibition in patients with coronary artery disease and preserved left ventricular function Ischemia Management with Accupril post-bypass graft via inhibition of angiotensin-converting enzyme (IMAGINE) compared with the other major trials in coronary artery disease.

It has been hypothesized that angiotensin-converting enzyme (ACE) inhibition, independent from its effect on ventricular function and blood pressure, could affect the atherosclerotic process and reduce the incidence of ischemic events and its complications. Several large clinical outcome trials were designed to test this hypothesis: QUIET, HOPE, EUROPA, PEACE, and IMAGINE. The results of the PEACE study were recently reported, leaving the IMAGINE study as the last chapter in our efforts to evaluate the role of ACE inhibition in coronary artery disease with preserved left ventricular function. In this report, we compare these studies with respect to their methodology and patient population and analyze the unique nature of the last ongoing study, IMAGINE. The reported studies show that patients with coronary artery disease who are at low-to-moderate or high risk should receive an ACE inhibitor if tolerated. However, when the absolute risk of a patient decreases, and intensive contemporary management is given, with good control of risk factors, the absolute and perhaps relative benefits of an ACE inhibitor decrease and their routine use in these patients may not be warranted. The role of ACE inhibition started early post-coronary artery bypass graft in patients with preserved left ventricular function, and intensive contemporary management remains to be determined and should get answered by the IMAGINE study. Moreover, the IMAGINE population is not only a lower risk population than those enrolled in HOPE or EUROPA, but also the risk for this population is bimodal in nature (early post-revascularization inflammation and thrombosis vs long-term atherosclerosis progression) and may provide further insight into underlying mechanisms.

Aged↗

PubMed1999

The influence of spatial reference frames on imagined object- and viewer rotations.

The human visual system can represent an object's spatial structure with respect to multiple frames of reference. It can also utilize multiple reference frames to mentally transform such representations. Recent studies have shown that performance on some mental transformations is not equivalent: Imagined object rotations tend to be more difficult than imagined viewer rotations. We reviewed several related research domains to understand this discrepancy in terms of the different reference frames associated with each imagined movement. An examination of the mental rotation literature revealed that observers' difficulties in predicting an object's rotational outcome may stem from a general deficit with imagining the cohesive rotation of the object's intrinsic frame. Such judgments are thus more reliant on supplementary information provided by other frames, such as the environmental frame. In contrast, as assessed in motor imagery and other studies, imagined rotations of the viewer's relative frame are performed cohesively and are thus mostly immune to effects of other frames.

Attention↗

PubMed2004

Imaginal perspective switches in remembered environments: transformation versus interference accounts.

Imaginal perspective switches are often considered to be difficult, because they call for additional cognitive transformations of object coordinates (transformation hypothesis). Recent research suggests that problems can also result from conflicts between incompatible sensorimotor and cognitive object location codes during response specification and selection (interference hypothesis). Three experiments tested contrasting predictions of both accounts. Volunteers had to point to unseen object locations after imagined self-rotations and self-translations. Results revealed larger pointing latencies and errors for rotations as compared to translations, and monotic latency and error increases for both tasks as a function of the disparity of object directions between real and imagined perspective. Provision of advance information about the to-be-imagined perspective left both effects unchanged. These results, together with those from a systematic error analysis, deliver clear support for an interference account of imaginal perspective switches in remembered surroundings.

Adult↗

PubMed1997

EEG-based discrimination between imagination of right and left hand movement.

Three subjects were asked to imagine either right or left hand movement depending on a visual cue stimulus. The interval between two consecutive imagination tasks was > 10 s. Each subject imagined a total of 160 hand movements in each of 3-4 sessions (training) without feedback and 7-8 sessions with feedback. The EEG was recorded bipolarly from left and right central and parietal regions and was sampled at 128 Hz. In the feedback sessions, the EEG from both central channels was classified on-line with a neural network classifier, and the success of the discrimination between left and right movement imagination was given within 1.5 s by means of a visual feedback. For each subject, different frequency components in the alpha and beta band were found which provided best discrimination between left and right hand movement imagination. These frequency bands varied between 9 and 14 Hz and between 18 and 26 Hz. The accuracy of on-line classification was approximately 80% in all 3 subjects and did not improve with increasing number of sessions. By averaging over all training and over all feedback sessions, the EEG data revealed a significant desynchronisation (ERD) over the contralateral central area and synchronisation (ERS) over the ipsilateral side. The ERD/ERS patterns over all sessions displayed a relatively small intra-subject variability with slight differences between sessions with and without feedback.

Adult↗

PubMed2003

Neurophysiological correlates of memory for experienced and imagined events.

Changes in slow cortical potentials within EEG were monitored while autobiographical memories of experienced and imagined event were generated and then held in mind for a short period. The generation of both kinds of memory led to significantly larger negative dc shifts over left versus right frontal regions, and this was interpreted as a reflection of substantial left frontal activation. The generation phase was also associated with greater right versus left negative dc shifts over posterior occipital regions. This pattern replicates and extends previous findings from our laboratory. In addition, however, experienced memories were associated with significantly larger negative dc shifts over occipito-temporal regions than imagined events. Furthermore, during the hold-in-mind period, imagined events led to larger negative dc shifts over left frontal regions than experienced events. These findings suggest that memories for imagined and experienced events may share control processes that mediate construction of memories but that they differ in the types of content of the memories: memories of experienced events contain sensory-perceptual episodic knowledge stored in occipital networks whereas memories for imagined events contain generic imagery generated from frontal networks.

Adult↗

PubMed2003

Comparison of actual and imagined execution of whole-body movements after a long exposure to microgravity.

Five cosmonauts were tested 30 days before a six-month space flight and also on the 2nd and the 6th day after their return to Earth. Cosmonauts performed and imagined a task that involved climbing two stairs to step onto a platform, jumping down with both feet and walking normally for a distance of 4 m. Durations of actual and imagined movements were measured by an electronic stopwatch. Results indicated that cosmonauts performed actual and imagined movements with similar durations before and after the space flight. However, the 2nd day after their return to Earth, cosmonauts significantly increased the durations of both actual and imagined movements. The durations of the imagined and actual movements returned to approximate pre-flight values 6 days after landing. Our results provide evidence that motor imagery process accurately replicates the neural and mechanical modifications which occur during the re-adaptation of the motor system on Earth's gravito-inertial environment after a long space flight.

Adaptation, Physiological↗

PubMed2002

Imaginative ethics--bringing ethical praxis into sharper relief.

The empirical basis for this article is three years of experience with ethical rounds at Uppsala University Hospital. Three standard approaches of ethical reasoning are examined as potential explanations of what actually occurs during the ethical rounds. For reasons given, these are not found to be satisfying explanations. An approach called "imaginative ethics", is suggested as a more satisfactory account of this kind of ethical reasoning. The participants in the ethical rounds seem to draw on a kind of moral competence based on personal life experience and professional competence and experience. By listening to other perspectives and other experiences related to one particular patient story, the participants imagine alternative horizons of moral experience and explore a multitude of values related to clinical practice that might be at stake. In his systematic treatment of aesthetics in the Critique of Judgement, Kant made use of an operation of thought that, if applied to ethics, will enable us to be more sensitive to the particulars of each moral situation. Based on this reading of Kant, an account of imaginative ethics is developed in order to bring the ethical praxis of doctors and nurses into sharper relief. The Hebraic and the Hellenic traditions of imagination are used in order to illuminate some of the experiences of ethical rounds. In conclusion, it is argued that imaginative ethics and principle-based ethics should be seen as complementary in order to endow a moral discourse with ethical authority. Kantian ethics will do the job if it is remembered that Kant suggested only a modest, negative role of principle-based deliberation.

Ethical Analysis↗

PubMed2000

Cross-modal source monitoring confusions between perceived and imagined events.

Two experiments tested the prediction based on the source monitoring framework that imagination is most likely to lead to false memories when related perceived events have occurred. Consistent with this, people were more likely to falsely remember seeing events when the events had been both imagined as seen and actually heard than when they were just heard, just visually imagined, or imagined both visually and auditorily. Furthermore, when people considered potential sources for memories or more carefully evaluated features of remembered events, source errors were reduced. On average, misattributed ("false") memories differed in phenomenal qualities from true memories. Taken together, these findings show that as different qualities of mental experience flexibly enter into source attributions, qualities derived from related perceptual events are particularly likely to lead to false claims that imagined events were seen, even when the event involves a primary modality (auditory) different from the target event (visual).

Adult↗

PubMed2001

Learning by imagining.

Five experiments were conducted to investigate the relative effectiveness of 2 alternative instructional strategies. Students who were engaged in studying worked examples that emphasized understanding and remembering procedures and concepts were compared with students who were engaged in imagining worked examples that emphasized imagining procedures and concepts. It was hypothesized that students who held prerequisite schemas would find imagining to have a beneficial effect on learning, compared with studying the material, whereas students who were less knowledgeable would find imagining to have a negative effect on learning, compared with studying. Experimental results were in accord with our hypotheses. It was concluded that, under specific circumstances, encouraging students to imagine procedures and concepts can substantially facilitate learning.

Adolescent↗

PubMed2004

In vivo versus imaginal smoking cue exposures: is seeing believing?

Smokers experience cigarette cravings in response to both imaginal and in vivo cigarette cues, and some studies suggest that the magnitude of this reactivity relates to difficulty quitting. Few studies, however, have systematically examined these two paradigms head-to-head. To this end, the authors exposed 225 smokers to imaginal and in vivo smoking cues and measured craving reactions. Results indicated that both imaginal and in vivo smoking cues increased craving. The magnitude of imaginal and in vivo reactions were statistically comparable and were moderately correlated. In vivo, but not imaginal, reactivity was related to duration of previous quits, particularly in men. Findings suggest that although both paradigms induce craving, the in vivo reactivity paradigm may be, at least in men, more effective for predicting smoking cessation failure.

Adult↗

PubMed1989

The composition of imaginal transformations.

Three experiments examine the performance of composite imaginal spatial transformations using tasks in which people perform pairs of distinct imaginal transformations either in close succession or simultaneously. The principal aim of the investigation is to determine, for both modes of composition, whether imaginal transformations combine interactively or noninteractively to determine the temporal course of imaging performance. Specifically, does the time to imagine a given composite transformation reflect the independent contributions of its component transformations, or do component transformations have different effects within different composites? Results obtained under a number of distinct task conditions are most consistent with the proposal of noninteractive composition. However, the temporal effects of particular imaginal transformations are neither consistent nor readily predictable across different task conditions. Implications of these results for analogue-spatial models, task demand, and procedural accounts of imaging are discussed.

Adolescent↗

PubMed1999

Point mutations in the guanine phosphoribosyltransferase from Giardia lamblia modulate pyrophosphate binding and enzyme catalysis.

Guanine phosphoribosyltransferase (GPRTase) from Giardia lamblia, an enzyme required for guanine salvage and necessary for the survival of this parasitic protozoan, has been kinetically characterized. Phosphoribosyltransfer proceeds through an ordered sequential mechanism common to many related purine phosphoribosyltransferases (PRTases) with alpha-D-5-phosphoribosyl-1-pyrophosphate (PRPP) binding to the enzyme first and guanosine monophosphate (GMP) dissociating last. The enzyme is a highly unique purine PRTase, recognizing only guanine as its purine substrate (K(m) = 16.4 microM) but not hypoxanthine (K(m) > 200 microM) nor xanthine (no reaction). It also catalyzes both the forward (kcat = 76.7 s-1) and reverse (kcat = 5.8.s-1) reactions at significantly higher rates than all the other purine PRTases described to date. However, the relative catalytic efficiencies favor the forward reaction, which can be attributed to an unusually high K(m) for pyrophosphate (PPi) (323.9 microM) in the reverse reaction, comparable only with the high K(m) for PPi (165.5 microM) in Tritrichomonas foetus HGXPRTase-catalyzed reverse reaction. As the latter case was due to the substitution of threonine for a highly conserved lysine residue in the PPi-binding loop [Munagala et al. (1998) Biochemistry 37, 4045-4051], we identified a corresponding threonine residue in G. lamblia GPRTase at position 70 by sequence alignment, and then generated a T70K mutant of the enzyme. The mutant displays a 6.7-fold lower K(m) for PPi with a twofold increase in the K(m) for PRPP. Further attempts to improve PPi binding led to the construction of a T70K/A72G double mutant, which displays an even lower K(m) of 7.9 microM for PPi. However, mutations of the nearby Gly71 to Glu, Arg, or Ala completely inactivate the GPRTase, suggesting the requirement of flexibility in the putative PPi-binding loop for enzyme catalysis, which is apparently maintained by the glycine residue. We have thus tentatively identified the PPi-binding loop in G. lamblia GPRTase, and attributed the relatively higher catalytic efficiency in the forward reaction to the unusual loop structure for poor PPi binding in the reverse reaction.

Animals↗

PubMed2004

[The importance of the phenomenom "imagination" in the scientific work of Werner Janzarik].

This paper in three parts and conclusion begins with the description of Janzarik's progression of thought, which originates in the narrowing of the gap between Jasper's descriptive phenomenology and anthropological phenomenology with its interpretive elements. Janzarik's structural-dynamic psychopathological approach has grown and differentiated from originally relatively narrow psychopathological questions to become an anthropology which aims to describe human assumptions concerning individual development/growth. The experience dimension is the focus, without suppressing interdisciplinary, objective findings, such as the inclusion of ethology. The mere clinical reconstruction of mental processes with all its heuristic risk was characterised by Janzarik as 'pure psychopathology'. In the section concerning structure and representation and their dependence on affect dynamic, we will emphasise the procedural nature of Janzarik's anthropology regarding developmental processes and its relationship to the philosopher Plessner's work in philosophy. The significance of the imagination in Janzarik's work contrasts to other philosophers who regard the imagination as ontological weakness, a deficiency, non-real, Janzarik, like Kant, sees the imagination as a constituent of reality. This will be exemplified in the characterisation of the mental field concerning the structural-dynamic model, the psychopathology of delusion as well as the oneiroid psychopathology. Finally the connection between autopraxis, Janzarik's core concept for the spontaneity of incidences and memory functions, and imagination will be described, which to a certain extent emphasises the working character of imagination for the flow of controlled mental activity. We will finish with the observation that Janzarik's work especially stresses experience and thus also the patient's individuality.

Anthropology↗

PubMed2007

Patients with hippocampal amnesia cannot imagine new experiences.

Amnesic patients have a well established deficit in remembering their past experiences. Surprisingly, however, the question as to whether such patients can imagine new experiences has not been formally addressed to our knowledge. We tested whether a group of amnesic patients with primary damage to the hippocampus bilaterally could construct new imagined experiences in response to short verbal cues that outlined a range of simple commonplace scenarios. Our results revealed that patients were markedly impaired relative to matched control subjects at imagining new experiences. Moreover, we identified a possible source for this deficit. The patients' imagined experiences lacked spatial coherence, consisting instead of fragmented images in the absence of a holistic representation of the environmental setting. The hippocampus, therefore, may make a critical contribution to the creation of new experiences by providing the spatial context into which the disparate elements of an experience can be bound. Given how closely imagined experiences match episodic memories, the absence of this function mediated by the hippocampus, may also fundamentally affect the ability to vividly re-experience the past.

Adult↗

PubMed2004

Functional connectivity during real vs imagined visuomotor tasks: an EEG study.

It is proposed that real and imagined movements activate identical neural networks. Cortical oscillatory activity is proposed as a mechanism through which distributed neuronal networks may bind into coherent ensembles and coupling of oscillators is used as a tool to investigate modulations of cortical connectivity. The aim of the present study was to test the hypothesis that, although the same brain network is involved in both real and imagined movements, the functional connectivity within the network differs. To do so, we measured interregional coupling, quantified using coherence between scalp EEG electrodes, during different periods of a prehension task during real and imagined movements. The results demonstrated a different pattern of coupling in the beta frequency range between electrodes overlying occipital and motor cortices during executed and imagined movements. These findings are consistent with the hypothesis that the neural networks during real and imagined movements are not identical.

Adult↗

PubMed1996

Close encounters in the liminal zone: experiments in imaginal communication part I.

The phenomenology of the experience of being in psychic contact with another person was explored in a series of observations using a novel dyadic interaction in imaginal space. Research participants working in pairs with eyes closed received instructions to imagine being in mental contact with one another for three minutes while they observed their internal experiences. Their reports indicated that the imagined contact was experienced as real, as intimate, and aroused the ambivalences usually associated with intimacy as well as phenomena suggestive of projective identification effects. This first part demonstrated that the liminal zone, or the transitional space between individuals, can be experimentally observed through the imagination. Part II of this report will present evidence that the experienced psychic contact was more than 'just imagination', and involved transpersonal interactions, including suggestions of synchronicity and telepathy.

Communication↗

PubMed2005

Lateral somatotopic organization during imagined and prepared movements.

Motor imagery is a complex cognitive operation that requires memory retrieval, spatial attention, and possibly computations that are analogs of the physical movements being imagined. Likewise, motor preparation may or may not involve computations that are analogs of actual movements. To test whether motor imagery or motor preparation activate representations that are specific to the body part whose movement is imagined or prepared, participants performed, imagined, and prepared hand movements while undergoing functional MRI scanning. Actual hand movements activated components of the motor system including primary motor and somatosensory cortex, the supplementary motor area, the thalamus, and the cerebellum. All of these areas showed strong lateral organization, such that moving a given hand activated the contralateral cortex and ipsilateral cerebellum most strongly. During motor imagery and motor preparation, activity throughout the motor system was much reduced relative to overt movement. However, significant lateral organization was observed during both motor imagery and motor preparation in primary motor cortex, the supplementary motor area, and the thalamus. These results support the view that the subjective experience of imagined movement is accompanied by computations that are analogs of the physical movement that is imagined. They also suggest that in this regard motor imagery and motor preparation are similar.

Adult↗