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PubMed2000

Neural correlates of imaginal aggressive behavior assessed by positron emission tomography in healthy subjects.

OBJECTIVE: Neurodegenerative or traumatic lesions of the frontal lobes often lead to abnormally aggressive behavior. The authors hypothesized that the imaginal evoking of scenarios involving aggressive behavior would be associated with a modulation of the functional activity in the human frontal cortex. METHOD: Regional cerebral blood flow (rCBF) determinations by positron emission tomography and psychophysiological measures of emotional responsivity were obtained in a group of 15 young healthy volunteers with good visual imagery abilities and no history of abnormal behavior while they imagined the same scenario with four variations involving emotionally neutral behavior and aggressive behavior. RESULTS: Compared to the imagined neutral scenario, the imagined scenarios involving aggressive behavior were associated with significant emotional reactivity and rCBF reductions in the ventromedial prefrontal cortex, suggesting that a functional deactivation of this cortical area occurs when individuals respond to the eliciting of imagined aggressive behavior. CONCLUSIONS: These results in healthy subjects further expand previous findings from animal and human studies by providing an in vivo functional demonstration of the involvement of the orbitofrontal cortex in the expression of aggressive behavior. They are also consistent with the hypothesis that a functional alteration of this cortical region may be present in individuals with pathological aggressive behavior.

Adult↗
PubMed1995

Does imagined exposure to the consequences of not ritualising enhance live exposure for OCD? A controlled study. I. Main outcome.

BACKGROUND: This randomised controlled study tested whether adding imagined to live exposure plus ritual prevention would enhance gains in obsessive-compulsive disorder (OCD). METHOD: Out-patients with OCD were randomly allocated to either have nine sessions of daily live self-exposure and ritual prevention to external cues alone (Ex) (n = 23) or to have, in addition to Ex, daily self-exposure to the imagined internal cues of the consequences of not ritualising (group Exi) (n = 23). All patients had the same sessional exposure time of 1 h 30 min (Exi 1 h live, 30 min imagined; Ex 1 h 30 min live), and had to practise either Exi or Ex daily for the same duration and to keep diaries of that self-exposure homework throughout treatment. Patients were followed up to week 32. Outcome measures were YBOCS for rituals and obsessions, compulsion checklist, target rituals and obsession, general anxiety, depression (Beck, Hamilton), work and social disability, clinical global impression (CGI). RESULTS: At weeks 4, 9, 20 and 32 the two groups improved similarly with no significant difference between them, neither for washers nor for checkers. Imagined exposure was more difficult to do than live exposure and there were more drop-outs. CONCLUSIONS: Daily imaged exposure to internal cues did not enhance exposure to external cues. Perhaps longer imagined exposure would have been more enhancing.

Adolescent↗
PubMed1997

Functional MRI mapping of occipital and frontal cortical activity during voluntary and imagined saccades.

We investigated the activation of frontal and occipital cortical areas in 14 normal volunteers during voluntary saccades in light or dark and during imagined saccades using functional magnetic resonance imaging (FMRI) with electro-oculogram monitoring. Voluntary saccades in light or dark and imagined saccades led to a significant activation (p < 0.005) of the precentral and posterior medial frontal gyrus (frontal eye field). The medial part of the superior frontal gyrus (supplementary eye field) also showed significant activity during voluntary saccades in all subjects, but only in four subjects during imagined saccades. In addition to frontal activity we found an activated primary visual cortex during voluntary saccades, both in light and in dark. In contrast to executed saccades, imagined eye movements revealed to occipital response under either condition. Our FMRI study supports the concept of frontal eye fields during voluntary saccades and demonstrates that occipital areas are associated with the generation of voluntary eye movements. However, the primary visual cortex is not active when eye movement is only imagined.

Adult↗
PubMed2002

Creating bizarre false memories through imagination.

The present study explored memory for familiar or usual actions (e.g., flip the coin) and bizarre or unusual actions (e.g., sit on the dice). In Session 1, action statements were presented to 210 participants, who had to either perform or imagine those actions. In Session 2, 24 h later, participants imagined performing various actions, some presented in the first session and others totally new. Finally, in Session 3, 2 weeks later, participants were tested on their memory for the original actions. We found that as the number of imaginings increased in Session 2, so did the proportion of did responses to actions that were only imagined or not even presented. This pattern was present for both bizarre and familiar actions. These results demonstrate that bizarre actions may lose the item distinctiveness that is used to make accurate memory decisions after repeated imagination.

Humans↗
PubMed1999

Discriminating memories for actual and imagined taste experiences: a reality monitoring approach.

Blindfolded subjects tasted 4 common fruits and imagined the taste of 4 others while focusing on either a few (low sensory detail [SD] or many (high SD) of the fruit's sensory qualities. One week later, subjects judged whether each of 12 fruit names represented a fruit that was previously tasted, imagined tasted, or new (reality monitoring). The major finding was a significant interaction between source (imagined, perceived) and SD level (low, high). Source monitoring was accurate for imagined and perceived fruits in the low SD condition and for perceived fruits in the high SD condition. As predicted, subjects tended to misattribute memories for imagined fruits to perception in the high SD condition. The findings are discussed with reference to the Johnson-Raye reality monitoring model and recent work on memory source confusions.

Adult↗
PubMed2000

Virtual reality as a new imaginative tool in psychotherapy.

Imagination, experience and memory play a central role in psychotherapy. These elements are fundamental in the life of everyone but also in the etiology of many psychological disturbance. Thanks to Virtual Reality (VR) it is possible to transcend the absolute and relative limits linked to individual potential. The imagines re-created through VR may be more vivid and real than the one that most subjects are able to describe through their own imagination and their own memory. In this chapter we focus the attention on imaginative techniques to find new ways of applications in psychotherapy. We will explore the way VR can be used to improve the efficacy of traditional techniques. VR produces a change with respect to the traditional relationship between client and therapist. Virtual experiences is a third way between "in imagination" and "in vivo" techniques in psychotherapy.

Humans↗
PubMedDate not supplied

Most adults show opposite-side biases in the imagined holding of infants and objects.

Three hundred university undergraduates were asked to imagine holding in their arms first an object (either an "expensive vase" or an "old shoebox") and then a young infant. For all three tasks, side biases were found that were significantly different from chance and from one another: 81% of the subjects reported holding the imagined vase in their right arm, 64% reported holding the imagined shoebox in their right arm, and 66% reported holding the imagined infant in their left arm. These results further support the hypothesis that the left-side bias is unique to infants and, for the first time, establish this through direct comparisons of holding-side biases for infants and objects within subjects. The sex and handedness of the holder as well as the qualities of the imagined object also were found to contribute to the side and strength of the bias.

Adult↗
PubMed1988

[Induced imagination as a methodologic paradigm in assessing stress perception and stress processing].

The methodological paradigm of the induced imagination has been tested as an alternative diagnostic access to stress and coping. Assumptions on the therapeutic applications of imagery techniques (i.e. Cautela, 1967; Lang, 1978; Leuner, 1980; Wolpe, 1958) have been integrated with cognitive concepts of visual imagery (Kosslyn, 1980; Kosslyn, Brunn, Cave & Wallach, 1984; Paivio, 1971; Steiner, 1980) to deduce a theoretical framework of emotional imagery. An emotionally involving imagery scene is generated when semantic-, spatial- and motoric-relational representations of an imagined scene are constructed and actions are to be performed by the subject. The electrodermal activity (EDA) serves as a physiological indicator of stress. Ten subjects have been tested. The main results are: 1. Stressful imaginations correlate with significantly higher physiological activity than relaxation phases and imagery scenes with agreable content. 2. Different sequences of a stressful imagination can be differentiated psychophysiologically: Parts of imagery appraisals and emotions show higher physiological activity than sequences which consist of descriptions of situational and environmental elements. 3. It could be shown that not the verbalisation itself but different contents of imagery scenes correlate with different physiological activities. These results provide strong support for the hypothesis that verbalisations of stressful events and coping strategies are related to increased physiological activity. The psychophysiological differentiation of stress processes implies the applicability of the induced imagination as a validity criterion for a criterion oriented questionnaire of stress and coping (Reicherts & Perrez, 1986).

Adaptation, Psychological↗
PubMed1994

[Imagination and desire: reflections on the determination of male sexuality].

Imagination and desire are looked upon as major determinants of male sexuality. In its various facets imagination represents one of the fundamental dimensions of human cognition. During the early phases of development the close interaction of imagination and erotic desire leads to the formations of psychical representatives of experiences of satisfaction that influence sexual and nonsexual behavior by establishing an internalized structure of blueprints for satisfaction. These blueprints can also be viewed as an important step in the development of autonomy. Sex differences can be found primarily in the function and employment of erotic fantasies. Compared to women men tend to use their erotic imagery to a much higher degree as a compensation for a lack of sexual satisfaction. Proceeding from the conceptual distinction of erotic and everyday realities, reflections on the zeitgeist of male sexuality and the relationship between the sexes are put forward focussing on the ambiguity of erotic imagination and the border crossing between the two realities. Based on these reflections therapeutic aspects of imagination and desire are touched upon and the problems of integrating erotic reality and everyday reality in long-term male-female relationships are discussed.

Erotica↗
PubMed1997

Arrowhead encodes a LIM homeodomain protein that distinguishes subsets of Drosophila imaginal cells.

The Arrowhead gene encodes a LIM-homeodomain transcription factor required for establishment of a subset of imaginal tissues: the abdominal histoblasts and the salivary gland imaginal rings. Consistent with its role in development, during embryogenesis Arrowhead is expressed in each abdominal segment and in the labial segment. Late in embryonic development, expression is refined to the abdominal histoblasts and salivary gland imaginal ring cells themselves. When ectopically expressed in imaginal disc cells, Arrowhead causes programmed cell death and loss of corresponding adult structures. Therefore, Arrowhead expression is required for development of one set of imaginal cells and is incompatible with development of another, emphasizing the specificity of Arrowhead and the sensitivity of different target cells to its expression. Loss-of-function mutations in Arrowhead affect conserved or invariant amino acids in the LIM- and homeo-domains demonstrating the importance of these residues in LIM homeodomain protein activity.

Abdomen↗
PubMed2000

Imaginal pioneers prefigure the formation of adult thoracic muscles in Drosophila melanogaster.

In insects, specialized mesodermal cells serve as templates to organize myoblasts into distinct muscle fibers during embryogenesis. In the grasshopper embryo, large mesodermal cells called muscle pioneers extend between the epidermal attachment points of future muscle fibers and serve as foci for myoblast fusion. In the Drosophila embryo, muscle founder cells serve a similar function, organizing large numbers of myoblasts into larval muscles. During the metamorphosis of Drosophila, nearly all larval muscles degenerate and are replaced by a set of de novo adult muscles. The extent to which specialized mesodermal cells homologous to the founders and pioneers of the insect embryo are involved in the development of adult-specific muscles has yet to be established. In the larval thorax, the majority of imaginal myoblasts are associated with the imaginal discs. We report here the identification of a morphologically distinct class of disc-associated myoblasts, which we call imaginal pioneers, that prefigures the formation of at least three adult-specific muscles, the tergal depressor of the trochanter and dorsoventral muscles I and II. Like the muscle pioneers of the grasshopper, the imaginal pioneers attach to the epidermis at sites where the future muscle insertions will arise and erect a scaffold for developing adult muscles. These findings suggest that a prior segregation of imaginal myoblasts into at least two populations, one of which may act as pioneers or founders, must occur during development.

Animals↗
PubMed2000

Cellular basis of the dynamic behavior of the imaginal thoracic discs during Drosophila metamorphosis.

The eversion, migration, spreading, and fusion of the thoracic imaginal discs during metamorphosis of Drosophila are described using timed whole-mount preparations and several molecular markers. The leading edge of the migrating disc epithelia consists of two groups of cells, stalk cells (S cells) and specialized imaginal cells (I cells), that both express the gene puckered. With this and other markers, opening of the stalk, eversion of the discs, migration of the leading edges, and fusion of the imaginal epithelia can be visualized in detail. Fusion is initiated by S cells that migrate over the larval epithelium and constitute a bridge between two imaginal epithelia. S cells are subsequently lost and imaginal fusion is mediated by the I cells that remain at the site of fusion. The possible cellular basis of this process is discussed. Fusion along the dorsal midline of the notum from the mesothoracic wing discs occurs earlier than that of the prothoracic and metathoracic discs, which remain in a lateral position. For a relatively long period (30 h) the mesothoracic epithelium becomes attached to the head and abdomen, causing a temporary local discontinuity of the order of segments. Later the pro- and metathoracic discs intercalate between head and mesothorax and between abdomen and mesothorax, respectively, to reestablish the normal order.

Animals↗
PubMed1996

An eye imaginal disc-specific transcriptional enhancer in the long terminal repeat of the tom retrotransposon is responsible for eye morphology mutations of Drosophila ananassae.

Optic morphology (Om) mutations of Drosophila ananassae are semidominant, neomorphic and nonpleiotropic, map to at least 22 loci scattered throughout the genome, and are associated with the insertion of the tom retrotransposon. Molecular and genetic analyses have revealed that eye morphology defects of Om mutants are caused by the ectopic or excessive expression of Om genes in the eye imaginal discs of third instar larvae. It is therefore assumed that the tom element carries tissue-specific gene regulatory sequences which enhance expression of the Om genes. In the present study, we examined whether or not the long terminal repeats (LTR) of the tom element contain such an eye imaginal disc-specific enhancer, using D. melanogaster transformants containing a lacZ gene ligated to the tom LTR. Analyses of lacZ gene expression in the eye imaginal discs of third instar larvae of 18 independently established transformant lines showed that the tom LTR was capable of enhancing lacZ expression in all the transformant lines, but the degree of enhancement varied between lines. In addition, the effect of the tom LTR lacZ gene evidently changed when the tom LTR construct was relocated to different chromosomal positions. On the basis of these findings, it is hypothesized that ectopic and excessive expression of the Om genes in the eye imaginal discs is induced by an eye imaginal disc-specific enhancer present in the tom LTR, the effect of which may be subject to chromosomal position effects.

Animals↗
PubMed1985

Dissociation and sorting out of Drosophila imaginal disc cells.

Previous attempts to study sorting out of Drosophila imaginal disc cells have been hampered by an inability to thoroughly dissociate these cells and the need to use cuticular markers which require several days of in vivo culture. This study overcomes these limitations by using a new dissociation procedure and a genetic marker for undifferentiated cells, the succinate dehydrogenase8 (sdh8) mutation. Dissociated and reaggregated cells from wing and leg imaginal discs segregated or "sorted out" from one another after only 24 hr of in vivo culture. It was also found that leg cells from different body segments may sort out, but to a lesser degree than wing and leg cells. Mixtures of wing and haltere cells did not sort out, in contrast to previous reports. These results constitute the first unambiguous study of sorting out with Drosophila imaginal disc cells and indicate that dorsally situated imaginal cells share a recognition specificity which is different from that of ventral imaginal cells.

Animals↗
PubMed1985

Intrinsic growth control in the imaginal primordia of Drosophila, and the autonomous action of a lethal mutation causing overgrowth.

Cell proliferation in Drosophila imaginal discs appears to be regulated by a disc-intrinsic mechanism involving local cell interactions that also control the formation of patterns of differentiation. This growth-control mechanism breaks down in animals homozygous for the mutation lethal (2) giant discs (l(2)gd) which remain as larvae for up to 9 days longer than normal. During this time cell proliferation continues in the imaginal discs as well as in the imaginal rings for the salivary glands, foregut, and hindgut, so that these tissues become greatly overgrown. When wild-type wing discs from mid-third instar larvae were removed and cultured for up to 28 days in wild-type female adult hosts, they grew and terminated growth at a cell number close to that which would be attained in situ by the time of pupariation. On the other hand, wing discs from l(2)gd homozygotes grew rapidly and continuously when cultivated in wild-type hosts, reached an enormous size, and acquired abnormal folding patterns. Overgrowth of mutant imaginal rings also continued during culture of these tissues in wild-type hosts. We conclude that overgrowth in this mutant is due to an autonomous defect in the imaginal primordia, which requires an extended larval period for its expression in situ.

Animals↗
PubMed1991

Involvement of Sarcophaga lectin in the development of imaginal discs of Sarcophaga peregrina in an autocrine manner.

The imaginal discs of Sarcophaga were found not to develop normally in the presence of galactose, a hapten sugar of Sarcophaga lectin, or anti-Sarcophaga lectin antibody. Wing and leg discs cultured with these substances became morphologically abnormal and no imaginal discs reached the stage of terminal differentiation, even in the presence of 20-hydroxyecdysone. The development of the imaginal discs was shown to be autonomously regulated in an autocrine manner by Sarcophaga lectin; namely Sarcophaga lectin was secreted by the imaginal discs in the presence of 20-hydroxyecdysone, and the stimulus of self-induced Sarcophaga lectin seemed to be indispensable for further development of the imaginal discs. Sarcophaga lectin was originally found as a defense protein, but these results show that it plays independent roles in both defense and development.

Animals↗
PubMed1994

Localization of thoracic imaginal-disc precursor cells in the early embryo of Drosophila melanogaster.

Our previous cell lineage analysis of the thoracic disc primordia of Drosophila showed that at the blastoderm and early gastrula stage, cells are not yet committed to form either larval or imaginal tissue (Meise and Janning, 1993). We have now refined our studies on the cell lineage and have mapped the imaginal primordia in the thoracic region. Homotopic transplantations of single cells within the thoracic region of blastoderm and early gastrula stages show that the precursor cells of thoracic imaginal discs are locally restricted to a small lateral area of the thoracic region. Clones labelling leg discs frequently included the Keilin's organs. Heterotopic transplantations along the dorsoventral axis indicate that cells within the thoracic region are not yet committed with respect to larval or imaginal tissue, their fate being dependent on the position where the transplanted cell had been deposited. On the other hand, cells taken from the abdominal anlagen and transplanted into the region of thoracic disc primordia could not participate in the formation of imaginal discs. This shows that, in contrast to the dorsoventral axis, determinative events had separated primordia along the anterior-posterior axis.

Animals↗
PubMed1997

Homeotic transformation of legs to mouthparts by proboscipedia expression in Drosophila imaginal discs.

The Drosophila homeotic gene proboscipedia (pb) specifies labial identify and directs formation of the adult distiproboscis from the labial imaginal discs. pb null alleles result in the homeotic transformation of the distiproboscis into prothoracic (T1) legs [Kaufman (1978) Genetics 90, 579-596; Pultz et al. (1988) Genes Dev. 2, 901-920]. Homology with other transcription factors, localization to the nucleus, and restricted embryonic and imaginal expression implicate the pb protein (PB) as a transcription factor. In order to examine the possible roles that PB may play in the specification of adult mouthparts, we have expressed PB in cells of wing, leg and eye-antennal imaginal discs and assayed for effects on the development of adult structures. We report here that the ectopic expression of PB in the imaginal discs under the control of the inducible GAL4 system [Brand and Perrimon (1993) Development 118, 401-415] alters the developmental program of adult legs into maxillary or labial palps. These homeotic transformations have an equal effect on all three sets of legs, indicating an activity that is not solely dependent upon the unique combinations of other homeotic genes present in each of the leg discs. Segment polarity genes required for establishing the AP compartment boundary were found to be undisturbed by ectopic PB. Furthermore, normal patterns of apoptosis are observed in animals expressing ectopic PB, indicating that PB does not alter or affect cell death. These results suggest that molecular events occurring downstream of the establishment of the compartment boundary are affected by ectopic PB expression in imaginal discs and point to a general role in 'palp' formation in addition to the specification of labial identity.

Animals↗