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PubMed2003

Updating space during imagined self- and array translations.

Previous work has demonstrated superior spatial updating performance during imagined viewer rotation versus imagined object/array rotation. Studies have also suggested that rotations are more difficult to process than translations. In three studies, we examined whether the advantage seen for updating during imagined self-rotations would generalize to translations. The participants updated the positions of objects in a line extending either to the front and back of the viewer or to the right and left after imagining viewer or array translation. Experiments 1 and 2 replicated the effects seen in imagined rotation tasks. A response time and accuracy advantage was found for imagined viewer translation versus imagined array translation. In Experiment 3, we directly compared real and imagined self- and array translations and demonstrated an advantage for real versus imagined array translation. The results suggest that the advantage for imagined viewer transformations is not a function of the specific transformation, but rather of the ability to imagine and predict the outcome of a moving frame of reference.

Humans↗
PubMedDate not supplied

Lateralization of brain activation to imagination and smell of odors using functional magnetic resonance imaging (fMRI): left hemispheric localization of pleasant and right hemispheric localization of unpleasant odors.

PURPOSE: Our goal was to use functional MRI (fMRI) of brain to reveal activation in each cerebral hemisphere in response to imagination and smell of odors. METHOD: FMRI brain scans were obtained in 24 normal subjects using multislice fast low angle shot (FLASH) MRI in response to imagination of banana and peppermint odors and in response to smell of corresponding odors of amyl acetate and menthone, respectively, and of pyridine. Three coronal sections selected from anterior to posterior brain regions were used. Similar studies were obtained in two patients with hyposmia using FLASH MRI and in one patient with hyposmia using echo planar imaging (EPI) both before and after theophylline treatment that returned smell function to or toward normal in each patient and in two patients with birhinal phantosmia (persistent foul odor) and global phantogeusia (persistent foul taste) with FLASH and EPI fMRI before and after treatment with neuroleptic drugs that inhibited their phantosmia and phantogeusia. Activation images were derived using correlation analysis. Ratios of hemispheric areas of brain activation to total hemispheric brain areas were calculated for FLASH fMRI, and numerical counts of pixel clusters in each hemisphere were made for EPI studies. Total pixel cluster counts in localized regions of each hemispheric section were also obtained. RESULTS: In normal subjects, activation generally occurred in left (L) > right (R) brain hemisphere in response to banana and peppermint odor imagination and to smell of corresponding odors of amyl acetate and menthone. Whereas there were no overall hemispheric differences for pyridine odor, activation in men was R > L hemisphere. Although absolute activation in both L and R hemispheres in response to banana odor imagination and amyl acetate smell was men > women, the ratio of L to R activation was women > men. In hyposmic patients studied by FLASH fMRI, activation to banana odor imagination and amyl acetate smell was L > R hemisphere both before and after theophylline treatment. In the hyposmic patient studied with EPI before theophylline treatment, activation to banana and peppermint odor imagination and to amyl acetate, menthone, and pyridine smell was R > L hemisphere; after theophylline treatment restored normal smell function, activation shifted completely with banana and peppermint odor imagination and amyl acetate and menthone smell to L > R hemisphere, consistent with responses in normal subjects. However, this shift also occurred for pyridine smell, which is opposite to responses in normal control subjects. In patients with phantosmia and phantogeusia, activation to phantosmia and phantogeusia before treatment was R > L hemisphere; after treatment inhibited phantosmia and phantogeusia, activation shifted with a slight L > R hemispheric lateralization. Localization of all lateralized responses indicated that anterior frontal and temporal cortices were brain regions most involved with imagination and smell of odors and with phantosmia and phantogeusia presence. CONCLUSION: Imagination and smell of odors perceived as pleasant generally activated the dominant or L > R brain hemisphere. Smell of odors perceived as unpleasant and unpleasant phantosmia and phantogeusia generally activated the contralateral or R > L brain hemisphere. With remission of phantosmia and phantogeusia, hemispheric activation was not only inhibited, but also there was a slight shift to L > R hemispheric predominance. Predominant L > R hemispheric differences in brain activation in normal subjects occurred in the order amyl acetate > menthone > pyridine, consistent with the hypothesis that pleasant odors are more appreciated in L hemisphere and unpleasant odors more in R hemisphere. Anterior frontal and temporal cortex regions previously found activated by imagination and smell of odors and phantosmia and phantogeusia perception accounted for most hemispheric differences.

Adult↗
PubMed2004

The imagination: cognitive, pre-cognitive, and meta-cognitive aspects.

This article is an attempt to situate imagination within consciousness complete with its own pre-cognitive, cognitive, and meta-cognitive domains. In the first sections we briefly review traditional philosophical and psychological conceptions of the imagination. The majority have viewed perception and imagination as separate faculties, performing distinct functions. A return to a phenomenological account of the imagination suggests that divisions between perception and imagination are transcended by precognitive factors of sense of reality and non-reality where perception and imagination play an indivisible role. In fact, both imagination and perception define sense of reality jointly according to what is possible and not possible. Absorption in a possible world depends on the strengths of alternative possibilities, and the relationship between core and marginal consciousness. The model may offer a parsimonious account of different states and levels of imaginal consciousness, and of how "believed-in imaginings" develop and become under some circumstances "lived-in experiences."

Cognition↗
PubMed1999

Asymmetries between dominant and non-dominant hands in real and imagined motor task performance.

Motor imagery is a dynamic state in which an individual mentally simulates the performance of a specific motor action or motor task. Recent behavioural and neuroimaging evidence suggests that the same neurocognitive networks control real and imagined movements. This hypothesis was tested by investigating whether motor asymmetries related to cerebral dominance also occurred for imagined movements. Fifty subjects performed the visually guided pointing task of Sirigu et al. [Sirigu, A., Duhamel, J., Cohen, L., Pillon, B., Dubois, B. and Agid, Y., The mental representation of hand movements after parietal cortex damage. Science, 1996, 273, 1564-1567.] using their dominant and non-dominant hands. Analysis of group data indicated that both real and imagined movement conformed to Fitts' law. Analysis of individual data indicated that asymmetries arising from motor dominance in real movements also occurred for imagined movements. However, the relative slowing and error associated with the non-dominant hand was greater for imagined movements than for real movements. These asymmetries support the hypothesis that real and imagined movements are represented within the same neurocognitive networks but suggest that asymmetries in performance related to handedness are greater for imagined movements. In addition, while the visually guided pointing task provides a useful test of the ability to make imagined movements, asymmetries in the speed and reliability of imagined performance are significantly greater than those for real performance.

Adolescent↗
PubMed2002

Does order and timing in performance of imagined and actual movements affect the motor imagery process? The duration of walking and writing task.

The purpose of the present study was to investigate the effects on the duration of imagined movements of changes in timing and order of performance of actual and imagined movement. Two groups of subjects had to actually execute and imagine a walking and a writing task. The first group first executed 10 trials of the actual movements (block A) and then imagined the same movements at different intervals: immediately after actual movements (block I-1) and after 25 min (I-2), 50 min (I-3) and 75 min (I-4) interval. The second group first imagined and then actually executed the tasks. The duration of actual and imagined movements, recorded by means of an electronic stopwatch operated by the subjects, was analysed. The duration of imagined movements was very similar to those of actual movements, for both tasks, regardless of either the interval elapsed from the actual movements (first group) or the order of performance (second group). However, the variability of imagined movement duration was significantly increased compared to variability of the actual movements, for both motor tasks and groups. The findings give evidence of similar cognitive processes underlying both imagination and actual performance of movement.

Adult↗
PubMed2003

Activation of cortical areas in music execution and imagining: a high-resolution EEG study.

Neuroimaging studies have shown that execution of a musical sequence on an instrument activates bilateral frontal opercular regions, in addition to bilateral sensorimotor and supplementary motor areas. During imagining activation of the same areas without primary sensorimotor areas was shown. We recorded EEG from 58 scalp positions to investigate the temporal sequence and the time course of activation of these areas while violin players prepared to execute, executed, prepared to imagine, or imagined a musical sequence on a violin. During the preparation for the sequence in three of seven musicians investigated the bilateral frontal opercular regions became active earlier than the motor areas and in one of them simultaneously with the motor areas. In two of the musicians a rather variable pattern of activation was observed. The frontal opercular regions were also strongly involved throughout the period of music execution or imagining. The supplementary motor area was involved in both preparation for the sequence and during execution and imagining of the sequence. The left primary sensorimotor area was involved in the preparation and termination of the musical sequence for both execution and imagining. The right sensorimotor area was strongly involved in the preparation for and during the execution of the sequence. We conclude that the bilateral frontal opercular regions are crucial in both preparation for and during music execution and imagining. They may have "mirror neurone" properties that underlie observation or imagining of one's own performance. The motor areas are differentially activated during the preparation and execution or imagining the sequence.

Adult↗
PubMed2003

Active-imaginal exposure: examination of a new behavioral treatment for cynophobia (dog phobia).

The aims of this study were to investigate exposure-based treatments for cynophobia (dog phobia) and to test a newly developed hybrid imaginal exposure treatment that we have named active imaginal exposure. The treatment introduces an in vivo coping component to imaginal exposure whereby the patient physically performs coping responses to an imagined feared stimulus. Eighty-two participants meeting DSM-IV criteria for specific phobia (animal subtype) were randomly assigned to one of three 30-min. treatments: (a) active-imaginal exposure (AI), (b) imaginal exposure alone (IE), or (c) graduated in vivo exposure (IV). Participants completed a behavioral approach test at pre, post, and four-week follow-up. Significant pre- to posttreatment improvement was observed in all three treatment conditions. Response rates at posttreatment were 51.9, 62.1, and 73.1% for the IE, AI, and IV groups respectively. Likewise, effect sizes at posttreatment were 0.76, 1.41, and 1.55 for the IE, AI, and IV groups respectively. Although in the predicted direction, the between group differences were not significant. A similar pattern of results was observed at follow-up. Further, safety behavior utilization during treatment was associated with less improvement--particularly in the two imaginal treatment conditions. Exposure treatments of dog phobia appear feasible and effective in reducing phobic fear and avoidance associated with dog phobia. Furthermore, preliminary evidence suggests that our active-imaginal exposure treatment may be a viable alternative to in vivo exposure.

Adaptation, Psychological↗
PubMed2005

The effects of hypnotic and nonhypnotic imaginative suggestion on pain.

BACKGROUND: Few studies have compared placebo and suggested pain reduction. PURPOSE: Hypnotic and nonhypnotic imaginative analgesia suggestions were compared against a placebo in reducing experimental pain. The mediator role of response expectancies and the moderator role of hypnotic and nonhypnotic imaginative suggestibility were evaluated. METHODS: Sixty participants previously assessed for hypnotic and nonhypnotic imaginative suggestibility were assigned to one of two experimental conditions or a no-treatment control condition. In the "placebo first" condition, participants received placebo, followed by imaginative and then hypnotic analgesia suggestions. In the "placebo last" condition, participants received imaginative and then hypnotic suggestions, followed by placebo. RESULTS: Imaginative and hypnotic suggestions did not differ significantly and were more effective than no treatment in reducing pain. The placebo was no different from the analgesia suggestions and was more effective than no treatment, but only when administered after the suggestions. Pain reduction was mediated by expectancy but was not significantly related to suggestibility or hypnotizability, the latter operationalized as hypnotic suggestibility with imaginative suggestibility statistically controlled. CONCLUSIONS: In the general population, nonhypnotic imaginative suggestions may be as effective as hypnotic suggestions in reducing pain. Response expectancies would seem to be an important mechanism of placebo and suggested pain reduction.

Humans↗
PubMed1993

A "fair" comparison of progressive and imaginal relaxation.

Progressive and imaginal relaxation-training procedures are difficult to compare because the latter takes many forms. In this study, an imaginal procedure was used that closely followed progressive operations except that muscle tension was imagined rather than experienced. The dependent variable was the total score on the Relaxation Inventory. College students were placed in groups (ns = 50) high and low on suggestibility based on scores on the Creative Imagination Scale, assigned in equal numbers to the imaginal and progressive relaxation conditions and given four sessions of relaxation training. The pre- and posttrials effects were significant within each of the four training sessions. There were no significant differences in reports of relaxation by the progressive and imaginal treatments. The expected cumulative effect of relaxation training across the four sessions was not found; in fact, the imaginal condition showed a significant decrease. The only significant suggestibility effect was an interaction between suggestibility and trials in which highly suggestible subjects reported less pre-session relaxation. These results are consistent with reports of no differences between progressive and imaginal relaxation training.

Adult↗
PubMed1979

Fact and fantasy: the roles of accuracy and variability in confusing imaginations with perceptual experiences.

In Experiment 1, pictures were presented to subjects two, five, or eight times, and subjects were asked to imagine each pciture two, five, or eight times. Subsequently, subjects estimated the number of times each picture had been presented. Their estimates of the frequency of these external events were influenced by imagination trials; this effect was greater for good imagers than for poor imagers. Experiment 2 involved a similar design in which subjects were asked either to imagine the same referent for a word or to imagine a different referent for a word on successive imagination trials. Consistency (same referent) did not increase the influence of imaginations on immediate judgments of external frequency. Thus, the results of Experiment 1 were attributed to the greater accuracy (as opposed to greater consistency) of good imagers' internal generations of the stimuli. Furthermore, variation (imagining different referents), like greater accuracy, increased the effects of imagination trials on immediate but not on delayed judgments of frequency. Possible mechanisms underlying these effects are discussed. In general, the two studies show that qualitative characteristics of completely covert generations influence their impact on estimates of the frequency of external events.

Form Perception↗
PubMed1998

Control of pupal commitment in the imaginal disks of Precis coenia (Lepidoptera: Nymphalidae).

When final (5th) instar larvae of Precis coenia were treated with the juvenile hormone analog (JHA) methoprene, they underwent a supernumerary larval molt, except for certain regions of their imaginal disks, which deposited a normal pupal cuticle. Evidently those regions had already become irreversibly committed to pupal development at the time JHA was applied. By applying JHA at successively later times in the instar, the progression of pupal commitment could be studied. Pupal commitment in the proboscis, antenna, eye, leg and wing imaginal disks occurred in disk-specific patterns. In each imaginal disk there were distinct initiation sites where pupal commitment began during the first few hours of the final larval instar, and from which commitment spread across the remainder of the disk over a 2- to 3-day period. The initiation sites were not always located in homologous regions of the various disks. As a rule, pupal commitment also spread from imaginal disk tissue to surrounding epidermal tissue. The regions of pupal commitment in all disks except those of the wings, coincided with the regions of growth of the disk. Only portions of the disk that had undergone cell division and growth underwent pupal commitment. Shortening the growth period did not prevent pupal commitment in the wing imaginal disk, indicating that, in this disk at least, a normal number of cell divisions was not crucial in reprogramming of disk cells for pupal cuticle synthesis. The apparent growth spurt of imaginal disks that occurs during the last part of the final larval instar is merely the final stage of normal and constant exponential growth. Juvenile hormone (JH) and ecdysteroids appeared to play little role in the regulation of normal imaginal disk growth. Instead, growth of the disks may be under intrinsic control. Interestingly, even though endogenous fluctuation in JH titers do not affect imaginal disk growth, exogenous JHA proved able to inhibit both pupal commitment, cell movement, and growth of the disks during the last larval instar. This function of JH could be important under certain adverse conditions, such as when metamorphosis is delayed in favor of a supernumerary larval molt.

Journal Article↗
PubMed1999

Cell determination and transdetermination in Drosophila imaginal discs.

Drosophila imaginal discs, the precursors of the adult fly appendages, are an important system for studying mechanisms of cell determination. How the different imaginal discs acquire and maintain their appendage-specific determined states are problems that have been addressed using experimental embryology as well as genetic and molecular approaches. Here we discuss the concept of cell determination and describe what is known about how determination is established and maintained in imaginal disc cells. The phenomenon of imaginal disc transdetermination, originally discovered in the 1960s, has remained an intriguing problem for understanding imaginal disc cell determination. We review the topic of imaginal disc transdetermination and describe how recent results from molecular genetic approaches have provided new insights into imaginal disc transdetermination and determination. We also discuss how an understanding of imaginal disc transdetermination can aid our understanding of parallel phenomena in other organisms, including human metaplasias.

Animals↗
PubMed1995

Establishment of Drosophila imaginal precursor cells is controlled by the Arrowhead gene.

Metamorphosis in Drosophila melanogaster requires synchronization of numerous developmental events that occur in isolated imaginal precursor tissues. The imaginal primordia are established during embryonic stages and are quiescent for much of larval life. The Arrowhead gene is necessary for establishment of proper numbers of cells within a subset of imaginal precursor tissues. Loss-of-function mutations in Arrowhead reduce the number of abdominal histoblasts and salivary gland imaginal ring cells before the proliferative stages of their development. The number of abdominal histoblasts in mutant animals is approximately half that of wild-type, as might result from failure of a single early division of these cells. A neomorphic Arrowhead allele results in the specific loss of the retinal precursors by the early third instar, before they have begun to differentiate. Since Arrowhead mutations affect only subsets of imaginal tissue, there must be distinctions in the developmental regulation of different imaginal precursors. Arrowhead may be part of a regulatory pathway responsible for establishing the proper number of abdominal histoblasts and salivary gland imaginal ring cells. The neomorphic Arrowhead allele, which may cause misexpression of the Arrowhead gene in the eye-antenna imaginal disc, interferes with the establishment or proliferation of retinal precursor cells.

Abdomen↗
PubMed1995

headcase, an imaginal specific gene required for adult morphogenesis in Drosophila melanogaster.

The majority of adult organs of a holometabolic insect like Drosophila melanogaster are derived from specific imaginal cells. These cells differ from their larval equivalents in many important cellular characteristics, ranging from the nature of the cell cycle to the timing and pattern of cellular differentiation. Here we describe the cellular, molecular and genetic characterization of a gene, headcase (hdc), which is required for imaginal cell development. hdc is the first gene to be described which is specifically expressed in all imaginal cells; this has allowed us to identify many imaginal primordia in the embryo and larval development. The Hdc protein is an extremely basic (pI 9.6) cytoplasmic protein with no obvious sequence similarities or conserved motifs. Interestingly, the spatial-temporal pattern of hdc expression prefigures imaginal cell re-entry into the mitotic cell cycle and persists until the final cell divisions. hdc null alleles have been isolated and found to cause pupal lethality, with dead pharate adults exhibiting defects in the differentiation of many adult tissues, most notably in head development. Ectopic expression of hdc, provided by a hdc-minigene, rescues the pupal lethality. Imaginal disc morphology in null mutants appears normal, therefore loss of hdc expression does not affect imaginal cell growth, but instead interferes with the ability of the imaginal primordia to differentiate properly during pupal development, suggesting that hdc may be involved in hormonal responsiveness during metamorphosis.

Animals↗
PubMed1978

[The objectivation of auditory and optical imaginations in the electroencephalogramm (author's transl)].

This study describes two new DC-potentials, which are related to auditory or optical imagination. The "auditory imagination potential" (AIP) is a negative DC-shift on the vertex lasting during the whole period of an auditory imagination. During an optical imagination there is a similar negative DC-shift in the ocipital region only. These "imagination potentials" can be already recognized in the "raw-EEG" by means of a special experimental technique. The magnitude of amplitudes correlates with the degree of concentration of the subject. In the case of intense imaginations potentials with amplitudes up to 20 muV and a duration of some seconds are recorded. The comparison between the vertex and the occipital lead permits the examination of the alternate occurence of auditory and optical conscious processes. The "imagination potentials" (AIP and OIP) are not related to any external stimulation or motor reaction and represent modality-specific EEG-correlates of cognitive, conscious processes (memory and imagination). Their significance for the "objective audiometry" is discussed.

Acoustics↗
PubMed1975

[The effect of alpha- and beta-ecdysone on differentiation of imaginal disks of Drosophila melanogaster cultivated in vitro].

The effect of alpha- and beta-ecdysone was studied upon differentiation of eye and leg imaginal discs of Drosophila cultivated together with neural ganglia in the medium C-39. In the medium without hormone, eye and leg imaginal discs from larvae of the early 3rd instar are not capable of differentiation. In these conditions, eye imaginal discs from larvae of the late 3rd instar become pigmented in 5 weeks and leg imaginal discs form sometimes segmented limbs on the 4th week of cultivation. In the medium with alpha- and beta-ecdysone, eye and leg imaginal discs from larvae of the early 3rd instar reveal only initial stages of differentiation. The effect of beta-ecdysone concentration was studied upon differentiation of leg and eye imaginal discs from larvae of the late 3rd instar. On decrease of beta-ecdysone concentration from 0.05 down to 0.005 mug/ml, initial stages of differentiation of leg imaginal discs proceed at a slower rate but, then, more complete differentiation with the formation of chitin and neuromuscular tissue is observed. In eye imaginal discs alpha-ecdysone at a concentration of 0.5 mug/ml and beta-ecdysone at a concentration of 0.005-0.5 mug/ml induce the pigment accumulation already at the 1st week of cultivation and beta-ecdysone at a concentration of 5 mug/ml fully inhibits the formation and accumulation of pigment.

Drosophila melanogaster↗
PubMed1978

Imaginal response events in systematic desensitization: a pilot study.

The primary focus of systematic desensitization (SD) is physiological responsivity in the presence of a conditioned aversive stimulus. However, SD also effects changes in motorapproach behavior and self-report. This study explores the possibility that SD directly affects the motor response system by way of conditioning covert approach responses in the presence of the imaginal aversive stimulus. Two independent variables were investigated: the content of instructions and actual covert motor responses during SD. Twenty-four subjects were classified as high- or low-responders on the basis of electromyographic responsiveness to instructions to imagine movement. Half the high- and half the low-responders were given a series of instructions to imagine-motor-approach behavior toward snakes. The remaining subjects received instructions to imagine only the snakes themselves with no reference to motor response. Imaginal scenes of 30-sec duration were alternated with relaxation periods of the same length. A significant difference was found between the posttreatment scores of high- and low-responders on performance measures, the high-responders performing better. The difference between the two instruction groups was not statistically significant. Self-report data suggested some subjects given instructions to imagine only snakes actually imagined themselves approaching snakes. Therefore, data were re-analyzed after instruction groups were reconstructed accordingly. A statistically significant difference was found on both factors. Continued investigation may further support imagery as covert behavior, open to empirical study.

Behavior Therapy↗
PubMed1997

An electroencephalographic study of imagined movement.

OBJECTIVE: Determine the generator sources for actual and imagined (simulated) movements of fingers and toes. DESIGN: Observational. SETTING: Electroencephalography laboratory. SUBJECTS: Ten asymptomatic adult volunteers. MAIN OUTCOME MEASURE: Comparison of cortical electrical fields and their dipole sources in actual and imagined movements. RESULTS: Cortical electrical fields tend to be contralateral with actual movements and midline with imagined movements. Dipole sources of actual movements include a contralateral contribution from the frontal (primary motor) area. Sources of imagined movements are midline or ipsilateral. CONCLUSIONS: (1) The motor networks underlying the generation of actual and imagined movements are different. (2) Imagined movements lack a primary motor area source, but involve medial and ipsilateral structures. (3) The effectiveness of imagined movements in rehabilitation may stem from activation of premotor or supplementary motor areas.

Adult↗