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Stimulus Conditions (stimulus + condition)
Selected AbstractsEnhanced effectiveness in visuo-haptic object-selective brain regions with increasing stimulus salienceHUMAN BRAIN MAPPING, Issue 5 2010Sunah Kim Abstract The occipital and parietal lobes contain regions that are recruited for both visual and haptic object processing. The purpose of the present study was to characterize the underlying neural mechanisms for bimodal integration of vision and haptics in these visuo-haptic object-selective brain regions to find out whether these brain regions are sites of neuronal or areal convergence. Our sensory conditions consisted of visual-only (V), haptic-only (H), and visuo-haptic (VH), which allowed us to evaluate integration using the superadditivity metric. We also presented each stimulus condition at two different levels of signal-to-noise ratio or salience. The salience manipulation allowed us to assess integration using the rule of inverse effectiveness. We were able to localize previously described visuo-haptic object-selective regions in the lateral occipital cortex (lateral occipital tactile-visual area) and the intraparietal sulcus, and also localized a new region in the left anterior fusiform gyrus. There was no evidence of superadditivity with the VH stimulus at either level of salience in any of the regions. There was, however, a strong effect of salience on multisensory enhancement: the response to the VH stimulus was more enhanced at higher salience across all regions. In other words, the regions showed enhanced integration of the VH stimulus with increasing effectiveness of the unisensory stimuli. We called the effect "enhanced effectiveness." The presence of enhanced effectiveness in visuo-haptic object-selective brain regions demonstrates neuronal convergence of visual and haptic sensory inputs for the purpose of processing object shape. Hum Brain Mapp, 2010. © 2009 Wiley-Liss, Inc. [source] Psychophysiological Assessment of Sexual Function in Women After Radiotherapy and Total Mesorectal Excision for Rectal Cancer: A Pilot Study on Four PatientsTHE JOURNAL OF SEXUAL MEDICINE, Issue 4 2009Stephanie O. Breukink MD ABSTRACT Introduction., The potential contribution of psychological and anatomical changes to sexual dysfunction in female patients following short-term preoperative radiotherapy (5 × 5 Gy) and total mesorectal excision (TME) is not clear. Aim., In this study we assessed female sexual dysfunction in patients who underwent radiotherapy and TME for rectal cancer. Main Outcome Measures., Genital arousal was assessed using vaginal videoplethysmography. Methods., Sexual functioning was examined in four patients who had rectal cancer and underwent radiotherapy and TME. All investigations were done at least 15 months after treatment. The results were compared with an age-matched group of 18 healthy women. Results., The patients and healthy controls showed comparable changes in vaginal vasocongestion during sexual arousal, though three out of four patients showed a lower mean spectral tension (MST) of the vaginal pulse compared with healthy controls. Subjective sexual arousal was equivalent between the two groups. Conclusions., In this study the changes of genital and subjective sexual arousal after erotic stimulus condition between patients and healthy controls were not different, though lower MST of the vaginal pulse was found in three out of four patients compared with healthy women. Additional work, however, must be performed to clarify the mechanisms of sexual dysfunction following treatment of rectal cancer. Breukink SO, Wouda JC, van der Werf - Eldering MJ, van de Wiel HBM, Bouma EMC, Pierie JP- EN, Wiggers T, Meijerink JWJHJ, and Weijmar Schultz WCM. Psychophysiological assessment of sexual function in women after radiotherapy and total mesorectal excision for rectal cancer: A pilot study on four patients. J Sex Med **;**:**,**. [source] The Defence Mechanism Test (DMT) revisited: experimental validation using threatening and non-threatening picturesEUROPEAN JOURNAL OF PERSONALITY, Issue 4 2002Bo Ekehammar Although the Defence Mechanism Test (DMT) has been in use for almost half a century, it is still unclear what it actually measures. The psychodynamic theory on which the test is based states that the threatful DMT pictures activate various defence mechanisms. To test this proposition, the original DMT pictures were redrawn by a professional artist, changing the emotional content without altering the structural properties. In this way, a neutral and a friendly variant were shaped. Sixty participants were randomly assigned to the threatful, neutral, and friendly stimulus conditions. In contrast to predictions made from psychodynamic theory, that the threatful picture would activate more ,signs of defence' than the others, the results disclosed that the three conditions activated the same amounts of ,signs of defence' and the same levels of various perceptual thresholds. Thus, rather than capturing psychodynamic defence mechanisms, our results suggest that the DMT taps perceptual or information-processing difficulties in correct identification of brief stimulus exposures regardless of their emotional contents. Copyright © 2002 John Wiley & Sons, Ltd. [source] fMRI reveals that non-local processing in ventral retinotopic cortex underlies perceptual grouping by temporal synchronyHUMAN BRAIN MAPPING, Issue 6 2008Gideon P. Caplovitz Abstract When spatially separated objects appear and disappear in a synchronous manner, they perceptually group into a single global object that itself appears and disappears. We employed functional magnetic resonance imaging (fMRI) to identify brain regions involved in this type of perceptual grouping. Subjects viewed four chromatically-defined disks (one per visual quadrant) that flashed on and off. We contrasted %BOLD signal changes between blocks of synchronously flashing disks (Grouping) with blocks of asynchronously flashing disks (no-Grouping). Results: A region of interest analysis revealed %BOLD signal change in the Grouping condition was significantly greater than in the no-Grouping condition within retinotopic areas V2, V3, and V4v. Within a single quadrant of the visual field, the spatio-temporal information present in the image was identical across the two stimulus conditions. As such, the two conditions could not be distinguished from each other on the basis of the rate or pattern of flashing within a single visual quadrant. The observed results must therefore arise through nonlocal interactions between or within these retinotopic areas, or arise from outside these retinotopic areas. Furthermore, when V2 and V3 were split into ventral and dorsal sub-ROIs, ventral retinotopic areas V2v and V3v preferentially differentiated between the two conditions whereas the corresponding dorsal areas V2d and V3d did not. In contrast, within hMT+, %BOLD signal was significantly greater in the no-Grouping condition. Conclusion: Nonlocal processing within, between, or to ventral retinotopic cortex at least as early as V2v, and including V3v, and V4v, underlies perceptual grouping via temporal synchrony. Hum Brain Mapp, 2008. © 2007 Wiley-Liss, Inc. [source] Confidence and decision type under matched stimulus conditions: overconfidence in perceptual but not conceptual decisionsJOURNAL OF BEHAVIORAL DECISION MAKING, Issue 3 2008Sara Kvidera Abstract Within the domain of metacognition, there is disagreement whether different processes underlie evaluations of confidence in perceptual versus conceptual decisions. The relationship between confidence and accuracy for perceptual and conceptual decisions was compared using newly created stimuli that could be used to elicit either decision type. Based on theories of Brunswikian and Thurstonian uncertainties, significant underconfidence for perceptual decisions and overconfidence for conceptual decisions were predicted. Three within-subjects experiments did not support this hypothesis. Participants showed significant overconfidence for perceptual decisions and no overconfidence for conceptual decisions. In addition, significant hard-easy effects were consistently found for both decision types. Incorporating our findings with past results reveals that both over- and underconfidence are attainable on perceptual tasks. This conclusion, in addition to the common presence of hard-easy effects and significant across-task correlations in over/underconfidence, suggests that confidence judgments for the two decision types may depend on largely shared processes. Possible contributions to confidence and over/underconfidence are explored, focusing on response time factors and participants' knowledge bases. Copyright © 2007 John Wiley & Sons, Ltd. [source] Long-Lasting Resistance to Extinction of Response Reinstatement Induced by Ethanol-Related Stimuli: Role of Genetic Ethanol PreferenceALCOHOLISM, Issue 10 2001Roberto Ciccocioppo Background: The conditioning of ethanol's reinforcing effects with specific environmental stimuli is thought to be a critical factor in long-lasting relapse risk associated with alcoholism. To study the significance of such learning factors in the addictive potential of ethanol, this experiment was designed (1) to characterize the effects of stimuli associated with alcohol availability on the reinstatement of responding at a previously ethanol-paired lever in rats with genetically determined ethanol preference versus nonpreference and (2) to examine the persistence of the motivating effects of these stimuli over time. Methods: Male alcohol-preferring (P) and alcohol-nonpreferring (NP) rats were trained to operantly self-administer ethanol (10% w/v) or water on a fixed-ratio 1 schedule in a 30-min daily session. Ethanol and water sessions were scheduled in random sequence across training days. Ethanol availability was signaled by an olfactory discriminative stimulus (banana extract, S+), and each lever press was paired with brief presentation of the conditioning chamber's house light (CS+). The discriminative stimulus signaling water availability (i.e., nonreward) consisted of anise odor (S,), and lever-responses during water sessions were paired with a brief white noise generation (CS,). The rats then were placed on extinction conditions during which ethanol and water, as well as the corresponding stimuli, were withheld. The effects of noncontingent exposure to the S+ versus S, paired with response-contingent presentation of the CS+ versus CS, on responding at the previously active lever were then determined in 30-min reinstatement sessions. To study the resistance to extinction of the effects of the ethanol-associated stimuli, additional tests were conducted at 3-day intervals for a total of 50 days. Results: The number of ethanol-reinforced responses during self-administration training was significantly greater in P than in NP rats (p < 0.01). After extinction, a significant recovery of responding was observed in both groups of rats under the stimulus conditions associated with ethanol (S+/CS+) but not those associated with water (S,/CS,). However, the response reinstatement was significantly greater in P than NP rats (p < 0.01). In addition, the results revealed a considerable resistance to extinction to the effects of the ethanol-associated stimuli. Throughout the 50-day test period, responding remained significantly above extinction levels in both P and NP rats (p < 0.01), but with an overall greater number of responses in P than NP rats (p < 0.05). Conclusions: The results support the hypothesis that conditioning factors contribute importantly to compulsive ethanol seeking and long-lasting vulnerability to relapse. In addition, the results suggest that genetic predisposition toward heightened ethanol intake extends to greater susceptibility to the motivating effects of ethanol-related environmental stimuli. [source] Effect of ,-adrenoceptor antagonists on autonomic control of ciliary smooth muscleOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 5 2002Barry Winn Abstract Purpose: Pharmacological intervention with peripheral sympathetic transmission at ciliary smooth muscle neuro-receptor junctions has been used against a background of controlled parasympathetic activity to investigate the characteristics of autonomic control of ocular accommodation. Methods: A continuously recording infra-red optometer was used to measure accommodation on a group of five visually normal emmetropic subjects under open- and closed-loop conditions. A double-blind protocol between saline, timolol and betaxolol was used to differentiate between the localised action on ciliary smooth muscle and effects induced by changes in stimulus conditions. Data were collected before and 45 min following the instillation of saline, timolol or betaxolol. Open-loop post-task decay was investigated following 3 min sustained near fixation of a stimulus placed 3 D above the subject's pre-task tonic accommodation level. Closed-loop dynamic responses were recorded for each treatment condition while subjects viewed sinusoidally (0.05,0.6 Hz) or stepwise vergence-modulated targets over a 2 D range (2,4 D). Results: Open-loop data demonstrate a rapid post-task regression to pre-task tonic accommodation levels for saline and betaxolol control conditions. A slow positive post-task shift was induced by timolol indicating that sympathetic inhibition contributes to accommodative adaptation during sustained near vision. Closed-loop accommodation responses to temporally modulated sinusoidal stimuli showed characteristic features for both saline and betaxolol control conditions. Timolol induced a reduced gain for low- and mid-temporal frequencies (< 0.3 Hz) but did not affect the response at higher temporal frequencies. Response times to stepwise stimuli increased following the instillation of timolol for the near-to-far fixation condition compared with the controls and was related to the period of sustained prior fixation. Conclusions: Modulation of accommodation under open- and closed-loop conditions by a non-selective ,-blocker is consistent with the temporal and inhibitory features of sympathetic innervation to ciliary smooth muscle. Although parasympathetic innervation predominates there is evidence to support a role for sympathetic innervation in the control of ocular accommodation. [source] The application of subliminal priming in lie detection: Scenario for identification of members of a terrorist ringPSYCHOPHYSIOLOGY, Issue 4 2009Ming Lui Abstract We studied a lie detection protocol immune to countermeasures. The 4 stimulus conditions were (1 and 2) supraliminal acquaintance name primed by subliminal acquaintance name (A-A) versus subliminal nonacquaintance name (N-A) and (3 and 4) supraliminal nonacquaintance name primed by subliminal acquaintance name (A-N) versus subliminal nonacquaintance name (N-N). In Experiment 1 and replication, principal components analysis-derived event-related potential components revealed significant differences between dishonestly answered supraliminal acquaintance conditions with differing primes (A-A vs. N-A). In Experiment 2 subjects were required to lie in A-N and N-N conditions, in contrast to Experiment 1, in which subjects lied in A-A and N-A conditions. No significant effects were found. In Experiment 3, the lying task was removed and no significant differences were found. We conclude that subliminal primes modulate ERPs in conditions with supraliminal acquaintance name when the task involves lying. [source] Stability of individual differences in cellular immune responses to two different laboratory tasksPSYCHOPHYSIOLOGY, Issue 6 2002Anna L. Marsland To explore the stability of immune reactivity across laboratory tasks, we correlated enumerative and functional lymphocyte responses to a speech task and a mental arithmetic task, delivered on the same occasion of testing in 31 healthy undergraduates. Both tasks were associated with an increase in peripheral CD8+ and CD56+ cell populations, and a decrease in proliferative response to phytohemagglutinin (PHA) and ratio of CD4:CD8 cells. Intertask correlations were significant for the magnitude of change in proliferative responses at two different concentrations of PHA, r= 0.76, p < .0001 and r= 0.46, p < .05, and in numbers of circulating CD56+ cells, r= 0.46, p < .005. Concomitant heart rate and systolic blood pressure responses also correlated significantly over the two experimental tasks (heart rate: r= 0.52 and systolic blood pressure: r= 0.58. ps < .0005). These data provide initial evidence that interindividual variability of some cellular immune responses is moderately reproducible across different stimulus conditions, providing further evidence that it may denote a stable individual difference. [source] | |||||||||||||