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PubMed2004

Randomised trial of a decision aid and its timing for women being tested for a BRCA1/2 mutation.

The aim of the study was to evaluate the impact of a decision aid (DA) and its timing in women being tested for a BRCA1/2 mutation. Women with and without a previous history of cancer were included after blood sampling for genetic testing. The DA consisted of a brochure and video providing information on screening and prophylactic surgery. To evaluate the impact of the DA, women were randomised to the DA group (n=184), receiving the DA 2 weeks after blood sampling, or to the control group (n=184). To evaluate the impact of timing, mutation carriers who had received the DA before the test result (n=47) were compared to mutation carriers who received the DA after the test result (n=42). Data were collected on well-being, treatment choice, decision and information related outcomes. The impact of the DA was measured 4 weeks after blood sampling. The impact of timing was measured 2 weeks after a positive test result. The DA had no impact on well-being. Regarding decision related outcomes, the DA group more frequently considered prophylactic surgery (P=0.02) corroborated with higher valuations (P=0.04). No differences were found for the other decision related outcomes. Regarding information related outcomes, the DA group felt better informed (P=0.00), was more satisfied with the information (P=0.00), and showed more accurate risk perceptions. Timing of the DA had no effect on any of the outcomes. No interactions were found between the DA and history of cancer. In conclusion, women being tested for a BRCA1/2 mutation benefit from the DA on information related outcomes. Because timing had no effect, the DA is considered useful either before or after the test result.

Adult↗
PubMed2000

Study of choice between accident and emergency departments and general practice centres for out of hours primary care problems.

OBJECTIVES: To determine the reasons for choosing between primary care out of hours centres and accident and emergency (A&E) departments for patients with primary care problems. METHODS: Interviews using a semistructured approach of samples of patients attending A&E departments and general practitioner (GP) out of hours centres for primary care problems. RESULTS: 102 patient interviews were undertaken. Sixty two per cent of A&E attenders were unemployed compared with 41% of out of hours attenders. White people were more likely to attend A&E departments and Asians the out of hours centre (p<0.01) and unemployed were more likely to attend A&E departments (70% v 30%). Some 46.3% of A&E department attenders had not contacted their GP before attending; 81.3% of first time users of the out of hours centre found out about it on the day of interview. Those attending A&E thought waiting times at the out of hours centre would be 6.3 hours (median) compared with a median perceived time of 2.9 hours by those actually attending the out of hours centre. Actual time was actually much less. CONCLUSION: Once patients have used the GP out of hours centre they are more likely to use it again. Education should be targeted at young adults, the unemployed and white people. Patients should be encouraged to contact their GP before A&E department attendance for non-life threatening conditions. Waiting time perception may be an important reason for choice of service.

Adult↗
PubMed1976

Mucociliary function of the eustachian tube: assessment by saccharin test in patients with dry perforations of the tympanic membrane.

The mucociliary function of the Eustachian tube was assess in 44 patients with dry perforations of the lympanic membrane by means of the saccharin test. A saccharin crystal was placed on the mucous membrane of the middle ear as close to the orifice of the Eustachian tube as possible, and the time taken for the patient to taste the saccharin was measured. The function of the Eustachian tube was also assessed by means of the aspiration test and by the Valsalva maneuver. No relationship was found between the results of the saccharin test, aspiration test, and the Valsalva maneuver. However, a correlation seems to exist between the hearing improvement obtained as determined by the postoperative air-bone gap, the positive or negative results of the saccharin test, and (in cases with positive saccharin test) the saccharin perception time.

Adolescent↗
PubMed1989

Acute effects of marijuana smoke on complex operant behavior in rhesus monkeys.

The acute behavioral effects of marijuana smoke were assessed in rhesus monkeys using a battery of food-reinforced complex operant tasks that included incremental repeated acquisition (IRA, n = 9), conditioned position responding (CPR, n = 8), progressive ratio (PR, n = 8), delayed matching to sample (DMTS, n = 6), and temporal response differentiation responding (TRD, n = 3). Marijuana or placebo smoke was delivered by a specialized face mask 15-min before sessions at exposure levels of 1, 5, 10, and 15 puffs (35cc/puff) or one cigarette smoked to a butt length of approximately 10 mm (approximately 20 puffs). Marijuana smoke caused significant disruptions of performance in all tests except PR after exposure to 10 or more puffs. Generally, response rates decreased or latencies to respond increased. Performance in the PR test was not consistently affected by marijuana exposure. Accuracy of responding was not altered by marijuana smoke at doses lower than those that decreased response rates in the IRA or CPR tests. In the three animals performing under all five schedules, the relative sensitivities for detecting marijuana behavioral effects were DMTS = TRD greater than IRA = CPR greater than PR. These results suggest that performance under operant schedules that are thought to represent some aspect of time perception, short-term memory, learning, motivation, and position discrimination show differential sensitivity to disruption by marijuana smoke, a finding similar to that noted previously for iv THC administration.

Animals↗
PubMedDate not supplied

[A new approach to psychosis. Is psychosis a disorder of mental reality?].

World's knowledge is but imperfectly intelligible to thinking beings by binding Possible with Reality of the experience meaning what resists them (matter or form) as sensible organ, while time perception remains out of feeling. Although the Reason seeks coherence in its seizing of the World, only consisting in experiences, yet the various experiences are not ordered a-priori towards coherence as an aim. The Reason ascribes the experiences to be pre-classified according to three modes: Continuity-Successiveness-Reversibility, connecting a physical fact (temporarily) to a thought fact (classifying). This motion towards a coherent understanding of the World proceeds by leaps over representations in three ways: 1-induction without requirement nor warranties. 2-analogical interpretation in which the middle term offers a slight validity. 3-demonstration where experiences get authentified but needs term successiveness undoubtedly marked in time. In case of a time mark deficiency, the demonstrative way gets out of warranty. The subject loses his free choice between Possible and Reality, causing psychosis. Yet the thought, getting improper to appreciate and correct the less gap between itself and experiences becomes else: thence, filtered by matter, it responds to chemotherapeutic strategies. The various symptoms in Psychosis can be brought to a selective deficit of the experience's pre classifying such as: -lack of "reversibility" troubling the course of thoughts, causing hermetism etc... -lack of "continuity" making easier experience materiality causing hallucinations. -defect of "successiveness" supporting the Possible for loss of the Reality causing delusion conviction.(ABSTRACT TRUNCATED AT 250 WORDS)

Awareness↗
PubMed2003

No influence of short-term exposure to 50-Hz magnetic fields on cognitive performance function in human.

OBJECTIVES: To examine whether 50-Hz magnetic fields acutely influence cognitive performance function in humans. METHODS: The exposure experiment was conducted in a wooden room with three-axis coils. Twenty young subjects were exposed to circularly polarized 50-Hz/20-mu T magnetic fields for 55 min, during which they were requested to perform four cognitive performance tests for evaluation of simple reaction time, time and accuracy of choice reaction, time perception, and figure perception. RESULTS: No subject detected the existence of the field. Statistical analysis revealed no significant influence of the exposure on the results of the tests. CONCLUSIONS: The results indicate that extremely low-frequency electromagnetic fields in the occupational environment are unlikely to interfere with human brain function so much as to lower working efficiency or accuracy.

Adult↗
PubMed1993

Behavioral approaches to toluene intoxication.

Toluene is a chemical that is very useful in our lives but harmful to our health. Behavioral toxicology has the merit of providing an accurate indication of functional toxicity to the CNS through the analysis of learned behavior and use of behavioral analysis techniques that give us various learning paradigms for investigating the effects of chemicals on memory, stimulus discrimination, attention, time perception, etc. Learning is a common ability among various species and it is possible to predict toxicity to human health from animals. Behavioral toxicology is assumed to play an important role in occupational and environmental health. Using typical test batteries such as shuttle, Sidman, and pole-climb avoidance, and FI, FR, DRL, and DMS tasks, the effects of toluene were investigated and the results were reviewed. One important objective of a test battery is to be able to detect already-known toxicity. Behavioral toxicology research indicated such effects of toluene toxicity as hyperactivity, ataxia, addiction, insomnia, and memory disturbances. Some excellent results which might indicate clinically unknown effects of toluene such as hearing loss, impairments of time discrimination, and improvements of STM were also demonstrated. Introduction of blood and brain toluene levels as an index of toluene exposure and more sophisticated learning tasks which reflect specific higher nervous functions of the CNS has been proposed.

Behavior↗
PubMed2003

50-60 Hz electric and magnetic field effects on cognitive function in humans: a review.

This paper reviews the effect of 50-60 Hz weak electric, magnetic and combined electric and magnetic field exposure on cognitive functions such as memory, attention, information processing and time perception, as determined by electroencephalographic methods and performance measures. Overall, laboratory studies that have investigated the acute effects of power frequency fields on cognitive functioning in humans are heterogeneous, in terms of both electric and magnetic field (EMF) exposure and the experimental design and measures used. Results are inconsistent and difficult to interpret with regard to functional relevance for possible health risks. Statistically significant differences between field and control exposure, when they are found, are small, subtle, transitory, without any clear dose-response relationship and difficult to reproduce. The human performance or event related potentials (ERPs) measures that might specifically be affected by EMF exposure, as well as a possible cerebral structure or function that could be more sensitive to EMF, cannot be better determined.

Brain↗
PubMed2006

Suppression of cutaneous reflexes by a conditioning pulse during human walking.

There are two ways in which responses to successive unexpected stimuli are attenuated, namely through habituation and conditioning. For the latter, it suffices that the unexpected stimulus is preceded by another just perceivable stimulus. In spinal cord reflexes this is termed conditioning, while in brainstem reflexes this is usually referred to as prepulse inhibition. Cutaneous reflexes in Tibialis Anterior (TA) are particularly strong during gait and they are thought to involve a transcortical loop. Can these reflexes be suppressed by giving a brief pulse prior to a reflex-evoking pulse given to the same nerve? To examine this question, electromyographic signals were recorded in healthy humans during walking. Sural nerve stimulation (train of five pulses (1 ms duration)) at 200 Hz were applied at two times perception threshold during different phases of the step cycle. The preceding pulse (single pulse of 1 ms at same intensity) was applied to the same nerve 150 ms before the reflex-evoking pulse train. Conditioning stimulation with a single pulse lowered significantly the following reflex response in the ipsilateral TA but much less in other muscles such as biceps femoris. The preceding pulse did not disturb the phase-dependent modulation or the typical reflex reversal. The finding that TA is selectively involved indicates that the suppressing mechanism may involve the motor cortex, which is known to be involved in the control of TA. The conditioning pulse did not cause a reduction in background activity. Therefore, the suppression of the reflex responses points to a premotoneuronal source such as presynaptic inhibition.

Adult↗
PubMed1996

Backward and forward walking use different patterns of phase-dependent modulation of cutaneous reflexes in humans.

1. The phase-dependent modulation of medium-latency (P2) (70-80 ms) responses in semitendinosus (ST), biceps femoris (BF), rectus femoris (RF), and tibialis anterior (TA) was studied with the use of low-intensity stimulation (2 times perception threshold) of the sural nerve. The shocks were given in a random order at 16 phases of the step cycle in 10 normal subjects during forward walking (FW) or backward walking (BW) on a treadmill. 2. All subjects exhibited P2 responses in all muscles studied both during BW and FW. The amplitude of the facilitatory P2 responses showed phase-dependent changes that could not have been predicted on the basis of the variations in background activity throughout the step cycle. 3. During FW, the P2 facilitatory responses in BF were large (with respect to the background activity) throughout the whole step cycle except for a short period near the end of the swing phase. In ST the responses were smaller and appeared primarily at the end of the stance phase and during the first part of the swing phase. During the second half of swing the P2 responses were basically suppressive. A modulation pattern similar to the one in ST was found in RF and TA, except that there was no reversal to suppressive responses in the swing phase in RF. Instead, a reduction in the amplitude of the facilitatory P2 responses occurred. 4. During BW, the modulation pattern recorded in the same subjects was different from the one seen during FW. Large facilitatory P2 responses were present in all muscles in middle and late swing. In the first half of stance the responses were most prominently seen in BF and RF. At the end of stance and/or at the onset of swing the facilitatory responses decreased in amplitude (BF and RF) or reversed to P2 suppressions (ST and TA). 5. We conclude that there are both facilitatory and suppressive pathways from the sural nerve to the leg muscles studied and that the balance of activity in these paths is phase dependent during both FW and BW. It is suggested that the phase-dependent modulation of P2 responses could largely rely on a central motor program. During BW the same motor program is used as during FW, but possibly running in reverse, thereby causing a shift both in the timing of the reflex reversal and in the periods of reflex suppression.

Adult↗
PubMed1989

Perception of time-altered monosyllables in a specific group of phonologically disordered children.

Temporal auditory processing of open (e.g. pie) versus closed (e.g. pipe) syllables in a specific group of phonologically impaired children who deleted word-final consonants and normal phonologically developing children between the ages of 4 and 7 yr was investigated. The disordered group demonstrated significantly poorer discrimination at the faster but not slower rates of speech. Imitation of word-final consonants did not significantly increase in the disordered subjects when presented with time-expanded speech although certain individuals made noticeable improvements. Discussion of temporal auditory processing deficits from a neuropsychological perspective which suggests different etiologies is offered.

Articulation Disorders↗
PubMed2006

A model of extended, semisystematic visual search.

OBJECTIVE: A model of semisystematic search was sought that could account for both memory retrieval and other performance-shaping factors. BACKGROUND: Visual search is an important aspect of many examination and monitoring tasks. As a result, visual search performance has been the topic of many empirical investigations. These investigations have reported that individual search performance depends on participant factors such as search behavior, which has motivated the development of models of visual search that incorporate this behavior. Search behavior ranges from random to strictly systematic; variation in behavior is commonly assumed to be caused by differences in memory retrieval and search strategy. METHODS: This model ultimately took the form of a discrete-time nonstationary Markov process. RESULTS: It yields both performance and process measures that include accuracy, time to perception, task time, and coverage while avoiding the statistical difficulties inherent to simulations. In particular, it was seen that as the search behavior becomes more systematic, expected coverage and accuracy increase while expected task time decreases. CONCLUSION: In addition to explaining these outcomes and their interrelationships from a theoretical standpoint, the model can predict these outcomes in practice to a certain extent as it can create an envelope defined by best- and worst-case search performance. APPLICATION: The model also has the capability of supporting assessment. That is, it can be used to assess the effectiveness of an individual's search performance, and to provide possible explanations for this performance, through the use of one or more of the output measures.

Awareness↗
PubMed2001

Abnormalities of spatial and temporal sensory discrimination in writer's cramp.

Clinical observations of patients with writer's cramp suggest that abnormalities of the sensory system may be a frequent finding in this disorder. Neurophysiological data from an animal model of focal dystonia have revealed cells in somatosensory cortex with enlarged and overlapping tactile receptive fields. However, psychophysical studies so far have been unable to document a clinical correlate supporting a similar enlargement of receptive fields in humans. We compared the fingertip discrimination of the orientation of fine spatial gratings between writer's cramp and control subjects and found a significant decrease in grating sensitivity in the patients, consistent with the possibility of enlarged tactile receptive fields. In addition, we duplicated previous experiments showing an abnormality of tactile temporal discrimination. The results provide psychophysical measures which may relate to the development of sensory cortical reorganization in patients with writer's cramp.

Adult↗
PubMed2004

No influence of 20 and 400 microT, 50 Hz magnetic field exposure on cognitive function in humans.

The aim of the present study was to investigate cognitive effects of a continuous, vertical extremely low frequency (ELF) magnetic field (MF) of 20 and 400 microT 50 Hz in healthy young men during performance on cognitive tests. Thirty-two volunteers (20-30 years old, mean 22.6 +/- 2.2 years) participated in this double blind study. The test protocol consisted of a set of tests: divided attention, flexibility, memory updating, digit span, digit span with articulary suppression, and time perception. The total duration of the exposure was 65 min. Participants were assigned four sessions: three conditions in the helmet (sham exposure, 20 and 400 microT) and one condition out of the helmet (to control the expectancy effect). No effect of MF exposure was observed on performance.

Adult↗
PubMed2004

On the development of low-level auditory discrimination and deficits in dyslexia.

Absolute auditory thresholds, frequency resolution and temporal resolution develop with age. It is still discussed whether low-level auditory performance is of clinical significance--specifically, for delayed maturation of central auditory processing. Recently, five new auditory tasks were used to study the development of low-level auditory discrimination. It was found that the development lasts up to the age of 16-18 years (on an average). Very similar tasks were now used with 432 controls and 250 dyslexic subjects in the age range of 7-22 years. For both groups the performance in one of the tasks was not related to the performance in another task indicating that the five tasks challenge independent subfunctions of auditory processing. Surprisingly high numbers of subjects were classified as low performers (LP), because they could not perform one or the other task at its easiest level and no threshold value could be assigned. For the dyslexics the incidence of LP was considerably increased in all tasks and age groups as compared with the age matched controls. The development of dynamic visual and optomotor functions and the corresponding deficits in dyslexia are discussed in relation to the auditory data presented here.

Adolescent↗
PubMed2004

Recollective qualities modulate hippocampal activation during autobiographical memory retrieval.

Recent neuroimaging studies report preferential hippocampal engagement during autobiographical memory (AM) retrieval. Although the basis of this preferential activation remains unclear, it may be related to the temporal specificity, recency, or recollective qualities of AMs, such as detail, emotionality, and personal significance. Typically, however, these variables are confounded, and thus we sought to investigate the contributions of each to hippocampal activation during AM retrieval. We conducted an event-related functional magnetic resonance imaging (fMRI) study in which participants retrieved temporally specific AMs and general, repeated AMs, and rated each for level of detail, emotion, or personal significance. These ratings, as well as the recency of AMs, were used in parametric modulation analyses to identify brain regions that correlated positively with ratings, independent of recency, and vice versa. Retrieval of AMs activated a number of regions, including the hippocampus. No differences in hippocampal activation were evident between specific and general AM retrieval, suggesting that temporal specificity, on its own, is not a key modulator of hippocampal activation. Activation of the left hippocampus during specific AM retrieval did vary with the level of detail, personal significance, and at a subthreshold level, emotionality, when the effect of recency was covaried out. Further, during general AM retrieval, all three recollective qualities modulated activity in the right hippocampus. Although the recency of specific AMs modulated hippocampal activation bilaterally, this effect dissipated in the left hippocampus when detail or emotionality was included as a covariate, and was no longer present in either hippocampus when personal significance was taken into account. Our results suggest that recollective qualities are important predictors of hippocampal engagement during AM retrieval independent of factors such as recency. These findings are consistent with theories of hippocampal function that emphasize its role in the recollection of multifaceted autobiographical experiences.

Adult↗
PubMed2001

Dissociating hippocampal subregions: double dissociation between dentate gyrus and CA1.

This study presents a double dissociation between the dentate gyrus (DG) and CA1. Rats with either DG or CA1 lesions were tested on tasks requiring either spatial or spatial temporal order pattern separation. To assess spatial pattern separation, rats were trained to displace an object which covered a baited food-well. The rats were then allowed to choose between two identical objects: one covered the same well as the sample phase object (correct choice), and a second object covered a different unbaited well (incorrect choice). Spatial separations of 15-105 cm were used to separate the correct object from the incorrect object. To assess spatial temporal order pattern separation, rats were allowed to visit each arm of a radial eight-arm maze once in a randomly determined sequence. The rats were then presented with two arms and were required to choose the arm which occurred earliest in the sequence. The choice arms varied according to temporal separation (0, 2, 4, or 6) or the number of arms that occurred between the two choice arms in the sample phase sequence. On each task, once a preoperative criterion was reached, each rat was given either a DG, CA1, or control lesion and then retested. The results demonstrated that DG lesions resulted in a deficit on the spatial task but not the temporal task. In contrast, CA1 lesions resulted in a deficit on the temporal task but not the spatial task. Results suggest that the DG supports spatial pattern separation, whereas CA1 supports temporal pattern separation.

Animals↗