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PubMed2005

Personality traits associated with perception of noxious stimuli in women with vulvar vestibulitis syndrome.

Vulvar vestibulitis syndrome (VVS) is associated with enhanced pain sensitivity. The present study explores the role of personality on the perception of noxious stimuli among women with VVS. More specifically, the aim of the study was to explore whether the personality traits assessed by Cloninger's Tridimensional Personality Questionnaire (TPQ) (harm avoidance [HA], novelty seeking [NS], and reward dependence [RD]) are associated with the augmented pain perception in women with VVS. Quantitative sensory tests were applied to the forearm of 98 women with VVS and 135 control subjects, all of whom completed the TPQ. The women with VVS scored higher than the control subjects on HA and RD with no significant differences in NS. Linear regression analyses revealed that in the VVS group, lower pain thresholds and higher magnitude estimations of suprathreshold pain stimuli were associated with higher HA and RD scores. The enhanced pain perception among women with VVS might reflect their tendency to respond intensely to signals of reward and to elevate the perceived risk. This might lead them to avoid hazards by overestimating the level of potential harm, as represented by greater pain sensitivity. The association between personality traits assessed by Cloninger's Tridimensional Personality Questionnaire, ie, harm avoidance, novelty seeking, and reward dependence, and the enhanced perception of noxious stimuli in vulvar vestibulitis syndrome might suggest neurochemical mechanisms of pain experience affected by personality, with possible application for future treatment approaches toward pain disorders.

Adolescent↗
PubMed2006

Plankton predation rates in turbulence: a study of the limitations imposed on a predator with a non-spherical field of sensory perception.

This paper presents an extension to previously published work which studied encounter rates of planktonic predators with restricted perception fields, to examine the related problems of prey capture and predation rates. Small-scale turbulence influences planktonic predation in two ways: the extra energy of the flow enhances the number of encounter events between individual predator and prey meso/micro-zooplankton, but it lowers the capture probability (because the time spent by the predator and prey in close proximity is reduced). Typically, an 'encounter' has usually been defined as an event when a potential prey swims (or is advected) to within a distance R of the predator in any direction. However, there is a considerable body of experimental evidence showing that predators perception fields are far from spherical; often they are wedge shaped (e.g. fish larvae), or strongly aligned with the directions of sensory antennae (e.g. copepods); and this is certain to influence optimal predation strategies. This paper presents a theoretical model which for the first time examines the combined problems of both encounter and capture for a predator with a restricted perception field swimming in a turbulent flow. If such a predator adopts a cruising strategy (continuous swimming, possibly with direction changes) the model predictions suggest that predation rates actually vary little with swimming speed, in contrast to predictions made for spherical perception fields. Consequently, cruising predators are predicted to swim at relatively low speeds whilst foraging. However, application of the model to examine the net energy gain of a typical pause-travel predator (the Atlantic cod larva), does predict the existence of an optimal ratio of the length of pauses to time spent swimming (specifically one pause phase to every two travel phases), in line with experimental observations. Kinematic simulations are presented which support these findings.

Animals↗
PubMed2004

Percept-related activity in the human somatosensory system: functional magnetic resonance imaging studies.

In this paper, we review blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) studies addressing the neural correlates of touch, thermosensation, pain and the mechanisms of their cognitive modulation in healthy human subjects. There is evidence that fMRI signal changes can be elicited in the parietal cortex by stimulation of single mechanoceptive afferent fibers at suprathreshold intensities for conscious perception. Positive linear relationships between the amplitude or the spatial extents of BOLD fMRI signal changes, stimulus intensity and the perceived touch or pain intensity have been described in different brain areas. Some recent fMRI studies addressed the role of cortical areas in somatosensory perception by comparing the time course of cortical activity evoked by different kinds of stimuli with the temporal features of touch, heat or pain perception. Moreover, parametric single-trial functional MRI designs have been adopted in order to disentangle subprocesses within the nociceptive system. Available evidence suggest that studies that combine fMRI with psychophysical methods may provide a valuable approach for understanding complex perceptual mechanisms and top-down modulation of the somatosensory system by cognitive factors specifically related to selective attention and to anticipation. The brain networks underlying somatosensory perception are complex and highly distributed. A deeper understanding of perceptual-related brain mechanisms therefore requires new approaches suited to investigate the spatial and temporal dynamics of activation in different brain regions and their functional interaction.

Attention↗
PubMed2006

Analysis of induced gamma-band activity in EEG during visual perception of Korean, English, Chinese words.

The oscillation of brain activities in the gamma-band is known to be a manifestation of the formation of neuronal assemblies that jointly constitute neural correlates of feature binding and conscious awareness. Visual word perception is a task that demands a considerable amount of cognitive resources and integration of information from multiple functionally connected neuronal circuits at various scales. Thus, it is anticipated that a substantial increase in gamma-band activity (GBA) would be observed during visual word perception. The purpose of this study was to examine whether meaningful increases in GBA occur during visual word perception and to explore similarities and differences in the amount and spatiotemporal GBA patterns while native Korean subjects perceive Korean, English, and Chinese words. We also aimed at identifying relationships between GBA increase and a behavioral measure such as response time. The results of power spectrum and time-frequency analyses showed that the increases in GBA were most significant in the prefrontal, frontal, and temporal sites, which are known to be relevant to visual word perception. The GBAs in the prefrontal and temporal sites were significantly correlated with response time. The differences in spatiotemporal patterns of GBA among languages were not prominent compared to inter-individual differences.

Adult↗
PubMed2004

The neural substrates of conscious color perception demonstrated using fMRI.

It is well established that seeing color activates the ventral occipital cortex, including the fusiform and lingual gyri, but less is known about whether the region directly relates to conscious color perception. We investigated the neural correlates of conscious color perception in the ventral occipital cortex. To vary conscious color perception with the stimuli-remaining constant, we took advantage of the McCollough effect, an illusory color effect that is contingent on the orientation of grating stimuli. Subjects were exposed to a specific combination of chromatic grating patterns for 10 min to induce the McCollough effect. We compared brain activities measured while the subjects viewed achromatic grating stimuli before (PRE) and after the induction of the McCollough effect (POST) using functional magnetic resonance imaging (fMRI). There were two groups: one group was informed that they would perceive illusory color during the session (INFORMED group), whereas the other group was not informed (UNINFORMED group). The successful induction of the McCollough effect was confirmed in all subjects after the fMRI experiment; nevertheless, only approximately half of the UNINFORMED subjects had been aware of the color during the POST session, while the other half had not. The left anterior portion of the color-selective area in the ventral occipital cortex, presumably V4alpha, was significantly active in subjects who had consciously perceived the color during MR scan. This study demonstrates the activity in a subregion of the color-selective area in the ventral occipital cortex directly related to conscious color perception.

Adult↗
PubMed2006

Sound alters activity in human V1 in association with illusory visual perception.

When a single brief visual flash is accompanied by two auditory bleeps, it is frequently perceived incorrectly as two flashes. Here, we used high field functional MRI in humans to examine the neural basis of this multisensory perceptual illusion. We show that activity in retinotopic visual cortex is increased by the presence of concurrent auditory stimulation, irrespective of any illusory perception. However, when concurrent auditory stimulation gave rise to illusory visual perception, activity in V1 was enhanced, despite auditory and visual stimulation being unchanged. These findings confirm that responses in human V1 can be altered by sound and show that they reflect subjective perception rather than the physically present visual stimulus. Moreover, as the right superior temporal sulcus and superior colliculus were also activated by illusory visual perception, together with V1, they provide a potential neural substrate for the generation of this multisensory illusion.

Acoustic Stimulation↗
PubMed2006

Haptic orientation perception: sex differences and lateralization of functions.

The present study examined sex differences in haptic orientation representation using three tasks: a bimanual parallel-setting task comprising haptic orientation perception and motor matching action, and two unimanual tasks focusing on the perception and action elements separately. A verbal judgment task focused on haptic orientation perception: participants were to assign a number of minutes to a felt orientation. An orientation production task required the rotation of a bar to match a verbally presented number of minutes. Although both male and female performance was systematically biased we found that males are more accurate in parallel-setting and verbal judgment of orientation, suggesting differences in haptic orientation perception, in particular. Increasing allocentric reference frame involvement by delaying the action in the parallel-setting task did not affect the sex difference found. In addition to a male advantage over tasks, performance on both unimanual tasks suggests sex differences in lateralization of haptic orientation processing; a dependence on hand orientation was found only for right hand performance in males.

Adolescent↗
PubMed2006

The influence of corticosteroids on the perception of dyspnea in asthma.

Corticosteroids are effective anti-inflammatory medications that are recommended for the control of persistent asthma. Little, however, is known about their influence on the perception of dyspnea, which, in turn, is important to the successful self-management of asthma. This paper provides a synopsis of available studies examining the impact of corticosteroids on the sensitivity to perceive dyspnea and presents possible mechanisms underlying this relationship. The results of these investigations are conflicting with some studies showing improved perception and other studies showing worsened perception of dyspnea after corticosteroid treatment. Thus, firm conclusions cannot be derived from the currently available data. Implications for future research, which is required to increase our understanding of potential influences of corticosteroids on the perception of dyspnea, are provided.

Anti-Inflammatory Agents↗
PubMed2006

Perception of blood transfusion risk.

Perceptions of risk ultimately drive the responses of individuals and society to risk issues, and transfusion risk is no exception. Surveys of lay people over the past decade indicate that public concern about transfusion safety has remained prevalent, dominated by the ongoing fear of contracting HIV infection. Such perceptions persist despite the acknowledgment that blood transfusion is safer now than in years past. Judgements by the lay public that may, at first glance, seem irrational can often be understood when the heuristics, biases, and models of human judgements of risk are considered. Risk perception research suggests that how lay people perceive risk has less to do with the unidimensional view of risk as a probabilistic expression and more to do with a complex multidimensional construct in which affect, reason, worldviews, trust, and other factors are intertwined. This review summarizes some of the principles of risk perception as applicable to transfusion medicine.

Blood Transfusion↗
PubMed2004

Medication management by the person with epilepsy: perception versus reality.

PURPOSE: In an attempt to understand if perception of medication management matched actual medication management, we examined epilepsy patients' perceptions of their overall medication management and their actual management. METHODS: The investigators interviewed 25 adults with refractory epilepsy regarding perceptions of their past overall medication management. Following the interview, each subject received the Medication Event Monitoring System (MEMS) and was asked to use it for 1 month. For the 21 persons who used and returned the caps, a score for compliance was calculated by dividing the number of compliant days by the total number of days. RESULTS: Four participants stated that they may sometimes forget to take their medications, and three patients said that they self-regulated their medications to fit their lifestyle. The self-regulation was not reflected in the MEMS cap data. Fourteen participants reported that it was not difficult to manage their medication regimen. MEMS cap data showed that 11 participants had a compliance score greater than 80% and 10 had a compliance score lower than 34%, but patients' perceptions of their past overall compliance did not differ between these groups. CONCLUSION: Although 14 of the participants reported that managing their medications was not a problem, MEMS cap data suggested that 10 of the participants did have difficulties managing their medication.

Attitude to Health↗
PubMed2005

Kids' perception about epilepsy.

PURPOSE: Epilepsy remains a stigmatized condition. Lack of information has been pointed to as a cause of the perpetuation of stigma. Our goal was to survey children's perception of epilepsy. METHODS: We used a questionnaire to determine if the children knew what epilepsy is and, if they did not know, what did they think epilepsy is. Twenty-nine children (15 girls; mean age 10 years, range 9-11 years) from a fourth-grade class of an elementary school in Campinas, Sao Paulo, Brazil, completed the questionnaires individually at the same time in the classroom. This took about 20 minutes. RESULTS: Only four children said they knew what epilepsy is: a disease of swallowing the tongue (3) and a disease that can kill (1). The perceptions of children who said they did not know what epilepsy is were: a disease that can kill, a disease of swallowing the tongue, a contagious disease, a serious illness, a head injury. Three children knew someone with epilepsy, and only two of them had said they knew what epilepsy is. CONCLUSION: The perceptions elicited from the children had a negative connotation; only one child mentioned a relationship between epilepsy and the brain. The spontaneous thoughts of children in this age group, without the contamination of political correctness, may reflect society's collective unconsciousness of the prejudice toward epilepsy and people with epilepsy and needs to be further investigated. Continuous, repetitive educational efforts are necessary in elementary school to change these negative perceptions of epilepsy in our society.

Child↗
PubMed2002

Learning and performance effects of accurate and erroneous knowledge of results on time perception.

Performance feedback (also known as knowledge of results or KR) has both performance and learning effects on many tasks. Earlier studies have demonstrated performance but not learning effects on time perception tasks. In this experiment, we dissociate and identify these two phenomena on two different time perception tasks. Participants were presented with either accurate (100%) or erroneous (80% or 120% of actual performance) KR on either a reproduction or a numerical estimation time perception task. Accurate (100%) KR reduced the group variability and increased the accuracy of response magnitude but left individual variability unchanged. Erroneous (80% or 120%) KR also reduced the group variability while leaving individual variation unchanged, but decreased the true accuracy of the response, with response magnitudes increasing for the 80% KR group and decreasing for the 120% group. Thus external KR that is in conflict with internal time cues overrides these internal cues and dictates response magnitude on these two tasks. Thus KR provides guidance for these behaviors. KR did not reduce the variability (dispersion) of participants' responses, but centered each participant's responses closer to the targeted performance. This decreased group response variability reflected a performance enhancing effect of KR because group response variability increased after KR was withdrawn. In contrast, response magnitudes remained changed for the duration of the post-KR period, indicating that KR also induced a learned response. Thus individual response variability, group response variability and response magnitude represent dissociable features of performance on these time perception tasks.

Adult↗
PubMed1998

Does risk perception affect behaviour and exposure? A pilot study amongst asbestos workers.

It is hypothesised that there is a causal association between workers' perceptions of the risks from handling hazardous materials, their behaviour while working and their consequent exposure. This has been investigated in a small group of workers carrying out remedial work on amosite insulating boards and similar products. Risk perception was first assessed using a questionnaire and then the workers' behaviour was recorded alongside task-based measurements of fibre exposure. There was a clear association of higher cumulative exposures when workers used power tools compared to manual methods (about seven times higher). Careful bagging was shown to reduce exposures by a smaller margin, (approximately half). Workers whose perception of the risks was poorer were found to be more likely to use power tools to remove the asbestos containing material. However, fibre exposure was not found to be directly associated with risk perception. Further work is necessary to clarify the validity of the original hypothesis.

Adult↗
PubMed2004

Effects of electric stimulation on C and A delta fiber-mediated thermal perception thresholds.

OBJECTIVE: To determine if interferential current (IFC) or transcutaneous electric nerve stimulation (TENS) alters C and A delta fiber-mediated thermal perception thresholds. DESIGN: Single-blind, randomized controlled trial. SETTING: Laboratory. PARTICIPANTS: One hundred forty healthy women volunteers (mean age +/- standard deviation, 20.6+/-2.7 y). INTERVENTIONS: Subjects were randomly and exclusively assigned to 1 of 7 groups (n=20 in each): 0, 5, and 100 Hz of IFC; 5 and 100 Hz of TENS; placebo and control stimulation. Stimulation was applied through 2 electrodes placed over the median nerve. Warm sensation, cold sensation, hot pain, and cold pain perception thresholds were measured from the thenar eminence by using a quantitative sensory testing device and a method of limits algorithm. MAIN OUTCOME MEASURES: Warm sensation, cold sensation, hot pain, and cold pain thresholds (degrees C) before, during, and after stimulation. RESULTS: There was a statistically significant effect of time for all 4 thermal perception thresholds (separate 2-way analyses of variance with repeated measures, all P<.001). There were no statistically significant differences between experimental groups, nor any interaction effects (all P>.05). CONCLUSIONS: Neither IFC nor TENS altered C and A delta fiber-mediated thermal perception thresholds. The results suggest that any analgesic mechanisms with these modalities are likely to be complex.

Adolescent↗
PubMed1999

Impaired categorical perception of synthetic speech sounds in schizophrenia.

BACKGROUND: Simple speech sounds such as /ba/ and /da/ differ in the frequency composition of their underlying formants. Normal volunteers asked to identify intermediate phonemes along the /ba/ to /da/ continuum abruptly switch from perceiving "ba" to perceiving "da". The present study investigates precision of phonemic processing in schizophrenia. METHODS: Categorical perception of speech sounds was evaluated in 15 schizophrenic and 14 control subjects, using a forced-choice phonemic discrimination paradigm. RESULTS: Patients and controls were equally able to recognize endpoint forms of both phonemes, but differed significantly in their perception of intermediate forms near the center of the continuum. Patients also showed a significantly shallower response curve, suggesting an impairment in boundary definition. Despite their impairment in categorical perception, schizophrenic subjects showed normal adaptation of response when test stimuli were preceded by a series of /ba/ or /da/ stimuli from the endpoints of the continuum. CONCLUSIONS: The present results suggest that precision of phonemic processing is impaired in schizophrenia. This categorical perception deficit may represent upward generalization of impaired memory-dependent acoustic processing. Deficits in the precision of cortical processing may contribute significantly to cognitive dysfunction in schizophrenia.

Adaptation, Psychological↗
PubMed2000

The positive and negative of human expertise in gaze perception.

Judging where others look is crucial for many social and cognitive functions. Past accounts of gaze perception emphasize geometrical cues from the seen eye. Human eyes have a unique morphology, with a large white surround (sclera) to the dark iris that may have evolved to enhance gaze processing. Here we show that the contrast polarity of seen eyes has a powerful influence on gaze perception. Adult observers are highly inaccurate in judging gaze direction for images of human eyes with negative contrast polarity (regardless of whether the surrounding face is positive or negative), even though negative images of eyes preserve the geometric properties of positives that are judged accurately. The detrimental effect of negative contrast polarity is much larger for gaze perception than for other directional judgements (e.g. judging which way a head is turned). These results suggest an 'expert' system for gaze perception, which always treats the darker region of a seen eye as the part that does the looking.

Adult↗
PubMed2002

Categorical perception of familiar objects.

We report three experiments where the categorical perception of familiar, three-dimensional objects was investigated. A continuum of shape change between 15 pairs of objects was created and the images along the continuum were used as stimuli. In Experiment 1 participants were first required to discriminate pairs of images of objects that lay along the shape continuum. Then participants were asked to classify each morph-image into one of two pre-specified classes. We found evidence for categorical perception in some but not all of our object pairs. In Experiment 2 we varied the viewpoint of the objects in the discrimination task and found that effects of categorical perception generalized across changes in view. In Experiment 3 similarity ratings for each object pair were collected. These similarity scores correlated with the degree of perceptual categorization found for the object pairs. Our findings suggest that some familiar objects are perceived categorically and that categorical perception is closely tied to inter-object perceptual similarity.

Adolescent↗
PubMedDate not supplied

The perception of sleep as a function of the level of daytime sleepiness among patients with obstructive sleep apnea.

Subjective estimates of sleep onset among patients with a variety of sleep disorders have been shown to be inaccurate. This inability in perceiving sleep onset is potentially dangerous for this population, in particular, for individuals who are required to drive long distances or operate heavy machinery as part of their daily activities. This study evaluated the perception of sleep among 237 consecutive patients diagnosed with obstructive sleep apnea. Patients completed an overnight sleep-laboratory evaluation followed by an objective evaluation of sleep propensity. The latter was done using the Multiple Sleep Latency Test (MSLT). Patients with an accurate perception of having slept on the MSLT were found to have shorter sleep latencies when compared with those with an inaccurate perception of their sleep. The results of this study suggest that the rapidity with which sleep is manifested is an important contributor to the accurate perception of sleep.

Adult↗