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PubMed1977

[Imaginal differentiation of the integument of the desert locust, Schistocerca gregaria Forsk. IV. Steps in morphogenesis of the glandular units].

In the gregarious males of Schistocerca gregaria Forsk., imaginal moulting (mitosis, apolysis, new cuticle synthesis, ecdysis) is associated with the differentiation of numerous glandular units. These units, involved in a sexual, excitatory pheromone secretion are at that time composed only of a basal glandular cell and an apical duct cell. Each glandular unit originates from an isogenic group of cells of which the four elements (tetrade) are disposed on two levels. At each level a principal cell and an accessory one may be recognized. The lower accessory, or ciliary, cell shows, at the time of apolysis, both a strong cytoplasmic protrusion and a typical ciliary formation. This formation associated with a diplosome goes through the duct cell and ends up in the exuvial space. It makes a inner mould; arranged around it are epicuticular materials characteristic of the duct wall; then it disappears. The strong cytoplasmic protrusion also retracts thus allowing a glandular reservoir to form. A glandular cell may be recognized at an early stage owing to its R.E.R. development. The upper accessory cell strengthens the duct cell and secretes junctional cuticle between the duct and general cuticle. Accessory cells, after the imaginal moult do not degenerate but acquire epithelial cell characteristics. The duct has a dual origin : the receptive part is secreted by the ciliary cell and the vector part by the duct cell. The organization and stages of morphogenesis of the glandular unit are discussed and compared to those of other apterygote or pterygote insects.

Animals↗
PubMed1983

Ultrastructure of cell death in gamma- or X-irradiated imaginal wing discs of Drosophila.

When Drosophila larvae were irradiated with 1300-1500 R of gamma rays both apoptotic and necrotic cell death were observed in imaginal wing discs. The ultrastructure of cell death by apoptosis was characterized by fragmentation of dead cells into highly condensed, membrane-bound particles. The ultrastructure of cell death by necrosis was characterized by cell lysis and organelle degeneration. Marked contrast was also seen in the distribution of the two types of cell death: apoptosis was universal in irradiated discs and affected widely distributed single cells, or small groups of cells, whereas necrosis formed lesions by afflicting large numbers of contiguous cells. It was noted that even where there were large lesions in the epithelial cell layer, which is the primary component of imaginal discs, the basement membrane associated with this epithelium always remained intact. Lesions could be identified in freshly extirpated discs by staining with trypan blue and were found in 50-70% of irradiated discs (depending on the larval age at the time of irradiation). Lesions were seen in all regions of the wing disc and varied greatly in size. In spite of extensive necrotic cell death wing discs developed into normal adult wings. Regenerative growth in this case would appear to require significant reorganization of cells. Implications of this for the appropriate interpretation of clonal analysis are discussed.

Animals↗
PubMed1975

Development and differentiation in vitro of Drosophila imaginal disc cells from dissociated early embryos.

Embryos of Drosophila melanogaster, 6-8 h after oviposition, were dissociated and the cells cultured in vitro. Besides larval cell types, imaginal disc cells, assembled and growing in bloated monolayered vesicles, were obtained. The cells of these vesicles become competent to differentiate adult structures when treated with alpha-ecdysone or ecdysterone in vitro. Recognizable patterns of the adult fly are not formed though. If metamorphosis of imaginal cell vesicles from in vitro-cultures is induced in vivo by transplantation into host larvae of various ages within the third larval instar, recognizable patterns can differentiate provided the host larva does not metamorphose prior to 2 days after transplantation. The frequency of specific patterns in the implants can be increased by providing 9 days of culture in vivo (adult host flies) before metamorphosis. Passage through the third larval instar is not essential for these cells to produce identifiable patterns since culture in adult flies alone can achieve this. The quality of the differentiated pattern is not correlated with the extent of cell proliferation in the cultured tissues. The problem of pattern specification in vitro and in vivo is discussed.

Animals↗
PubMed1997

Imagined halitosis: a social phobia symptom?

Imagined halitosis is poorly documented in the psychiatric literature. It is perhaps best thought of as a symptom rather than as a specific syndrome (a collection of symptoms that co-vary together). Many of the cases with imagined halitosis described in the literature resemble the psychiatric syndrome of social phobia.

Diagnosis, Differential↗
PubMed1979

Factor M as a correlate of physical fitness: imagination or just more energy.

Determined whether 16PF scale scores could contribute significantly to the prediction of a measure of fitness. Sixty-three firemen from a large metropolitan area in the Southeast were Ss. Factor M contributed significantly to the prediction of one measure of fitness (i.e., treadmill time). The assumption cited in the literature that Factor M reflects "imagination" in individuals who score high on fitness measures was questioned. The article concluded that Cattell's earlier work relating high Factor M to high energy and endurance suggests a more logical interpretation of Factor M vis à vis measures of fitness.

Adult↗
PubMed1990

The imagination and psychological healing.

As one of the internal senses or inward wits, the imagination was long thought to play a crucial role in the age-old struggle between the rational and the irrational, and it was conceived of as a faculty that might be damaged in some forms of psychopathology. During the Renaissance it emerged as a force or factor with a considerable potential for causing harm in the form of disease and for doing good in the form of curing disease. Its place in psychological healing has been significant for much of the time since then, including a lively attention to it in the work of Carl Jung and in the guided imagery techniques of recent decades.

Europe↗
PubMed2007

Comparison of the neural basis for imagined writing and drawing.

Drawing and writing are complex processes that require the synchronization of cognition, language, and perceptual-motor skills. Drawing and writing have both been utilized in the treatment of aphasia to improve communication. Recent research suggests that the act of drawing an object facilitated naming, whereas writing the word diminished accurate naming in individuals with aphasia. However, the relationship between object drawing and subsequent phonological output is unclear. Although the right hemisphere is characteristically mute, there is evidence from split-brain research that the right hemisphere can integrate pictures and words, likely via a semantic network. We hypothesized that drawing activates right hemispheric and left perilesional regions that are spared in aphasic individuals and may contribute to semantic activation that supports naming. Eleven right-handed subjects participated in a functional MRI (fMRI) experiment involving imagined drawing and writing and 6 of the 11 subjects participated in a second fMRI experiment involving actual writing and drawing. Drawing and writing produced very similar group activation maps including activation bilaterally in the premotor, inferior frontal, posterior inferior temporal, and parietal areas. The comparison of drawing vs. writing revealed significant differences between the conditions in areas of the brain known for language processing. The direct comparison between drawing and writing revealed greater right hemisphere activation for drawing in language areas such as Brodmann area (BA) 46 and BA 37.

Adult↗
PubMed2006

Neuroscience and imagination: the relevance of Susanne Langer's work to psychoanalytic theory.

This paper presents the work of philosopher Susanne Langer and argues that her conceptualization of the human mind can provide psychoanalysts with a unique framework with which to theoretically combine interpretive and biological approaches to their work. Langer's earlier work in the philosophy of symbols directs her investigation into the biological sciences along the lines of sentience and imagination, which in turn become the cornerstones of her theory of mind. Langer's understanding of the continuing transformation of affect into language is a decisive contribution yet to be built upon by others.

Affect↗
PubMed2006

American psychology and the religious imagination.

In just three generations, American psychology grew from a fledgling science to a culturally authoritative discipline. Standard accounts of psychology's meteoric rise typically omit what most needs to be illuminated: the resonance between psychological theory and the symbolic universe underlying America's popular religious imagination. This article sketches a cultural history of American psychology by examining how many of its core concepts invoke a metaphysical horizon associated with the nation's heritage of unchurched spirituality.

History, 19th Century↗
PubMed2006

Language use in imagined dialogue and narrative disclosures of trauma.

Support exists in many populations for the use of written disclosure to express thoughts and emotions about a traumatic experience. The present study examined language use in a variation of the writing task modified to include an imagined dialogue with another person. We hypothesized that this method would increase cognitive, affective, and present-tense word use, all of which are linked with beneficial outcomes from writing. We randomly assigned 169 college students to write in one of three conditions: trauma narrative, trauma dialogue, or control writing. Results suggested that writing about traumatic experiences in the form of a dialogue promotes greater present-oriented, affective experiencing and cognitive processing than does writing in the form of a narrative.

Adolescent↗
PubMed1996

The excitability of the human motor cortex increases during execution and mental imagination of sequential but not repetitive finger movements.

Motor potentials (MEPs) evoked by focal (figure-of-eight coil) transcranial magnetic stimulation of the left motor cortex were recorded from the right opponens pollicis (OP) and flexor digitorum superficialis (FDS) of 14 normal subjects during different motor tasks. Changes in motor cortical excitability under behavioural conditions presumably connected with premotor and supplementary motor area (SMA) activation were investigated by comparing the size of the MEPs obtained during: (1) rest, (2) mental calculus, (3) repetitive left thumb-to-index opposition, (4) mental simulation of the same task with the right hand, (5) sequences of left thumb-to-fingers opposition, and (6) mental simulation of the same sequences with the right hand. MEP size significantly increased in both muscles during sequential movements of the left hand and sequence simulation with the right hand, but not during mental calculus or actual or simulated repetitive movements. The H-reflex evoked in the OP and FDS muscles by electrical stimulation of the median nerve (at wrist and elbow, respectively) under the same experimental conditions did not show significant modifications. The increase in MEP size during non-routine actual or imagined sequences of finger movements supports the view that the SMA is activated under these conditions and that it exerts a direct facilitatory influence on the motor cortex.

Adult↗
PubMed2002

Effects of subthalamic nucleus stimulation on actual and imagined movement in Parkinson's disease : a PET study.

BACKGROUND: PET studies in moderately affected Parkinson's disease (PD) patients reveal abnormal cerebral activation during motor execution and imagery, but the effects of subthalamic nucleus (STN) stimulation are not well established. OBJECTIVES: to assess the effect of STN stimulation on cerebral activation during actual and imagined movement in patients with advanced PD. METHODS: seven severely affected PD patients treated with bilateral STN stimulation were studied with PET and H(2)(15)O. The following conditions were investigated: (1). rest; (2). motor execution of a sequential predefined joystick movement with the right hand and (3). motor imagery of the same task. Patients were studied with and without left STN stimulation while right stimulator remained off. RESULTS: Without STN stimulation, the primary motor cortex was activated only during motor execution whereas the dorsolateral prefrontal cortex (DLPFC) was activated only during motor imagery. An activation of the supplementary motor area (SMA) was seen during both motor execution and motor imagery. Left STN stimulation during motor execution increased the regional cerebral blood flow (rCBF) bilaterally in the prefrontal cortex including DLPFC, in the left thalamus and putamen. In addition, a reduction of rCBF was noted in the right primary motor cortex, inferior parietal lobe and SMA. Under left STN stimulation, during motor imagery, rCBF increased bilaterally in the DLPFC and in the left thalamus and putamen and decreased in the left SMA and primary motor cortex. CONCLUSION: STN stimulation during both motor execution and imagery tends to improve the functioning of the frontal-striatal-thalamic pathway and to reduce the recruitment of compensatory motor circuits notably in motor, premotor and parietal cortical areas.

Aged↗
PubMed2001

Responsible engineering: the importance of character and imagination.

Engineering Ethics literature tends to emphasize wrongdoing, its avoidance, or its prevention. It also tends to focus on identifiable events, especially those that involve unfortunate, sometimes disastrous consequences. This paper shifts attention to the positive in engineering practice; and, as a result, the need for addressing questions of character and imagination becomes apparent.

Character↗
PubMed1989

Can we imagine how objects look from other viewpoints?

Many psychologists who study cognition believe that perception achieves object-centered representations that make it possible to extract representations of how the object would appear from differing viewpoints. Others believe we can achieve representations of how an object would appear by a process of visualization or mental rotation. We report experiments in which the subject tries to imagine how three-dimensional novel wire objects would appear from positions other than the one they are in. Subjects are unable to perform this task unless they make use of strategies that circumvent the process of visualization. It is suggested that the linear increase in time required to succeed in mental rotation tasks as a function of the angular discrepancy between the figures compared is the result of increasing difficulty rather than of the time required for rotation.

Adult↗
PubMed1995

Do schizophrenics not differentiate between perception and imagination? an EEG study using dimensional analysis.

The electroencephalograms (EEGs) of 18 chronic schizophrenic patients and 16 controls were compared during three experimental conditions: simple mental arithmetic, the perception of a moving double pendulum, and the imagination of it. An elevated dimensional complexity of the EEG of schizophrenic patients during perception as compared to normals and a failure to increase dimensional complexity during mental imagery was found. No differences were found during mental arithmetic. It is concluded that the brains of schizophrenics operate during perception in a functional state that is characterised by increased and apparently unnecessary complexity.

Adult↗
PubMed1996

Do imagined and executed actions share the same neural substrate?

This paper addresses the issue of the functional correlates of motor imagery, using mental chronometry, monitoring the autonomic responses and measuring cerebral blood flow in humans. The timing of mentally simulated actions closely mimic actual movement times. Autonomic responses during motor imagery parallel the autonomic responses to actual exercise. Cerebral blood flow increases are observed in the motor cortices involved in the programming of actual movement (i.e. premotor cortex, anterior cingulate, inferior parietal lobule and cerebellum). These three sources of data provide converging support for the hypothesis that imagined and executed actions share, to some extent, the same central structures.

Autonomic Nervous System↗
PubMed2006

The power of simulation: imagining one's own and other's behavior.

A large number of cognitive neuroscience studies point to the similarities in the neural circuits activated during the generation, imagination, as well as observation of one's own and other's behavior. Such findings support the shared representations account of social cognition, which is suggested to provide the basic mechanism for social interaction. Mental simulation may also be a representational tool to understand the self and others. However, successfully navigating these shared representations--both within oneself and between individuals--constitutes an essential functional property of any autonomous agent. It will be argued that self-awareness and agency, mediated by the temporoparietal (TPJ) area and the prefrontal cortex, are critical aspects of the social mind. Thus, differences as well as similarities between self and other representations at the neural level may be related to the degrees of self-awareness and agency. Overall, these data support the view that social cognition draws on both domain-general mechanisms and domain-specific embodied representations.

Brain↗
PubMed2006

Remembering the past and imagining the future: common and distinct neural substrates during event construction and elaboration.

People can consciously re-experience past events and pre-experience possible future events. This fMRI study examined the neural regions mediating the construction and elaboration of past and future events. Participants were cued with a noun for 20s and instructed to construct a past or future event within a specified time period (week, year, 5-20 years). Once participants had the event in mind, they made a button press and for the remainder of the 20s elaborated on the event. Importantly, all events generated were episodic and did not differ on a number of phenomenological qualities (detail, emotionality, personal significance, field/observer perspective). Conjunction analyses indicated the left hippocampus was commonly engaged by past and future event construction, along with posterior visuospatial regions, but considerable neural differentiation was also observed during the construction phase. Future events recruited regions involved in prospective thinking and generation processes, specifically right frontopolar cortex and left ventrolateral prefrontal cortex, respectively. Furthermore, future event construction uniquely engaged the right hippocampus, possibly as a response to the novelty of these events. In contrast to the construction phase, elaboration was characterized by remarkable overlap in regions comprising the autobiographical memory retrieval network, attributable to the common processes engaged during elaboration, including self-referential processing, contextual and episodic imagery. This striking neural overlap is consistent with findings that amnesic patients exhibit deficits in both past and future thinking, and confirms that the episodic system contributes importantly to imagining the future.

Adolescent↗