High speed x-ray processing for surgery.
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Humans↗
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Results for “processing speed”
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Speed of information-processing and structural limitations by mentally retarded and dual-diagnosed retarded-schizophrenic persons.
Three experiments were conducted in an investigation of information-processing capabilities of mentally retarded adults, nonretarded children (mental age control), and nonretarded adults (chronological age control). In all experiments, one of two target stimuli was presented to the center and to the right or left of central fixation. Subjects were required to detect the presence of a stimulus in a yes-no forced-choice paradigm (Experiment 1), identify which of the two targets had been presented in a forced-choice discrimination paradigm (Experiment 2), or distinguish between the targets in a forced-choice discrimination task when the target was preceded by, presented stimultaneously with, or followed by a patterned noninformational masking stimulus. The findings support the theory of a structural defect in mentally retarded persons that results in slow information-processing.
Adult↗
Speed of lexical and nonlexical processing in French: the case of the regularity effect.
Words with irregular spelling-sound correspondences are read aloud more slowly than words with regular spelling-sound correspondences. This so-called regularity effect is modulated by word frequency, with low-frequency words showing larger costs than do high-frequency words. Because French has more regular spelling-to-sound correspondences than English, we expected a different pattern in French than in English. This was indeed the case, since regularity effects were obtained for both high- and low-frequency words in French. We further showed that a French implementation of the dual-route cascaded model could not account for this pattern. In additional simulations, we investigated whether this failure was due to lexical processes being too fast (leaving little time for the nonlexical route to interfere) or nonlexical processes being too slow. The results showed that only speeding up the nonlexical route allowed the model to capture the data. This suggests that the delayed phonology assumption that characterizes nonlexical processing in the original model needs to be abandoned in a more regular orthography.
Humans↗
Adult age differences in strategy use during verbal fluency performance.
This study investigated adult age differences in strategy use during verbal fluency performance among 60 older and 60 younger adults. Clustering and switching, strategic components of fluency, were investigated as predictors of performance along with cognitive processes thought to underlie these strategies, namely verbal ability, speed of processing and executive function (strategic planning, performance monitoring, etc.). Two measures of verbal fluency were used: initial and excluded letter (words produced not containing a designated letter). These tasks both require search for words based on a phonemic cue but are thought to reflect a differential reliance on strategic retrieval search processes for successful performance. The number of clusters produced accounted for age differences in excluded, but not initial, letter fluency. Performance on both fluency tasks was associated with the number of clusters and switches participants produced and initial letter fluency was associated with cluster size for older adults and a ratio index of effective search for both age groups. In general, both fluency tasks relied on verbal ability and articulation speed, and excluded letter fluency performance relied more on speed and executive function than did initial letter fluency, especially for older adults.
Adolescent↗
Parkinsonism due to manganism in a welder: neurological and neuropsychological sequelae.
A 33-year-old welder with 3 years of exposure to manganese (Mn) bearing welding fumes was seen by neurologists for cognitive and motor complaints. He exhibited signs and symptoms of Parkinson's disease, including tremor, bradykinesia, gait disturbance and cogwheel rigidity. However, he was young and had significant inattention and forgetfulness, had found levodopa unhelpful and moved with a cock-walk gait, all of which suggested manganism. His serum and urine levels of Mn were, in fact, elevated, and his brain MRI had increased T1-weighted signal intensities in the basal ganglia bilaterally (globus pallidus) consistent with Mn deposition. Two years later, he underwent comprehensive neuropsychological testing. Clinical history indicated a mild tremor and emotional dysfunction with irritability, anxiety, and depression with psychotic features. He showed deficits in cognitive flexibility, information processing and speed, and greatly reduced motor speed, which are consistent with a fronto-subcortical process. These findings support a diagnosis of early onset parkinsonism from welding.
Adult↗
Evidence of a perceptual-encoding deficit in narcolepsy?
Body temperature, vigilance, memory, information processing and motor function were examined in 10 unmedicated narcoleptics and 10 matched controls at four different times of day. Time of day and body temperature were not related to performance. Narcoleptics displayed selective cognitive deficits in response latency, word recall, and estimation of frequency. Narcoleptics did not differ from controls in motor speed, vigilance, information processing speed or decision-making accuracy. We propose that a perceptual-encoding deficit may underlie the problems in memory and complex reaction time associated with narcolepsy.
Adolescent↗
Cognitive impairment in three subtypes of multiple sclerosis.
Patients with relapsing, primary progressive, and secondary progressive MS were administered the Tower of London and the Stroop Color-Word Interference Test, yielding several measures of executive function and speeded information processing. MS patients' performance was compared with healthy controls and with a clinical control group consisting of patients with rheumatoid arthritis. The MS patients performed the tests more slowly, but did not differ from either group of controls on measures of executive function. Slowing in the speed of information processing was characteristic of MS patients across two basic tasks differing in terms of controlled versus automatic processing and in terms of whether or not rapid responding was an explicit feature of successful performance. Although evident in all subtypes, this slowing was more pronounced in secondary progressive patients and somewhat less pronounced in primary progressive patients. Furthermore, the slowing was unrelated to patients' disability status or level of depression.
Adult↗
Low- and high-affinity reactions in rapid neurotransmission.
Until 1950-1960, most physiologists were reluctant to accept chemical neurotransmission. They believed that chemical reactions were much too slow to account for the speed of synaptic processes. The first breakthrough was to discover the impressive velocity of acetylcholinesterase. Then, nicotinic receptors provided an example of complex ultrarapid reactions: fast activation at a low ligand affinity, then desensitization if the ligand is not rapidly removed. Here, we describe synaptic transmission as a chain of low-affinity rapid reactions, assisted by many slower regulatory processes. For starting quantal acetylcholine release, mediatophores are activated by high Ca2+ concentrations, but they desensitize at a higher affinity if Ca2+ remains present. Several mechanisms concur to the rapid removal of Ca2+ from the submembrane microdomains. Among them, the Ca2+/H+ antiport is a typical low-affinity, high-speed process that certainly contributes to the rapidity of neurotransmission.
Acetylcholine↗
An exponential pyramid model of the time-course of size processing.
Two prior approaches to size processing are discussed in this paper. The first approach is based on measurements of mental size transformations, the second on measurements of thresholds for size and separation. We first analyze these prior approaches and point out differences among prior models and similarities among prior results. This analysis led to new psychophysical experiments that tested the effect of size, relative precision, and eccentricity on the speed of perceptual processing. Speed was not affected by size, but was affected by relative precision and eccentricity. These new results, along with prior results, are then used to formulate a new model based on an exponential pyramid algorithm. This new model, which uses elements of both traditional approaches, can better account for prior, as well as our new results, on the time-course of size processing.
Algorithms↗
Densitometric comparisons of Ultra-speed, Ektaspeed, and Ektaspeed Plus intraoral films for two processing conditions.
This study compared film speed, contrast, exposure latitude, and resolution of Ultra-speed, Ektaspeed, and Ektaspeed Plus films (Eastman Kodak Co., Rochester, N.Y.). Densitometric curves were generated for each film type under processing conditions of fresh and used chemistry to observe their effect on factors associated with diagnostic quality. Ektaspeed Plus film displayed the least variability due to processing condition of any film; it also demonstrated the fastest speed and was twice as fast as Ultra-speed film. Ektaspeed exhibited the greatest relative exposure latitude followed by Ektaspeed Plus and Ultra-speed. Average gradient over a clinically useful range of densities was greatest for Ultra-speed in fresh processing solutions, but greatest for Ektaspeed Plus in used processing solutions. All film types were able to resolve more than 16.6 line pairs per millimeter regardless of processing conditions. The results of this study suggest that dental practitioners who have refrained from using E-speed film because of the sensitivity of this film to variations in processing may now consider providing this dose-reducing technology for their patients with the expectation of obtaining consistent image quality.
Absorptiometry, Photon↗
Adult age differences in the speed and capacity of information processing: 2. An electrophysiological approach.
A total of 60 subjects performed different variants of the Sternberg memory search task in an experiment designed to evaluate aging differences in the speed of the human information-processing system. The present study examined the nature of the age-related slowing using convergent methodologies of Sternberg's additive factors logic, the speed-accuracy trade-off, and the P300 component of the event-related brain potential. These methodologies revealed that a substantial component of slowing was manifest in perceptual encoding, response criterion adjustment, and response execution, with a lesser component related to memory search speed.
Adult↗
Selectivity for speed gradients in human area MT/V5.
Cortical area MT/V5 in the human occipito-temporal cortex is activated by visual motion. In this study, we use functional imaging to demonstrate that a subregion of MT/V5 is more strongly activated by unidirectional motion with speed gradients than by other motion patterns. Our results suggest that like the monkey homolog middle temporal area (MT), human MT/V5 contains neurons selective for the processing of speed gradients. Such neurons may constitute an intermediate stage of processing between neurons selective for the average speed of unidirectional motion and neurons selective for different combinations of speed gradient and different motion directions such as expanding optical flow patterns.
Adult↗
Teaching with a video system improves the training period but not subsequent success of tracheal intubation with the Bullard laryngoscope.
BACKGROUND: The Bullard laryngoscope is useful for the management of a variety of airway management scenarios. Without the aid of a video system, teaching laryngoscopy skills occurs with indirect feedback to the instructor. The purpose of this study was to determine if use of a video system would speed the process of learning the Bullard laryngoscope or improve the performance (speed or success) of its use. METHODS: Thirty-six anesthesia providers with no previous Bullard laryngoscope experience were randomly divided into two groups: initial training (first 15 intubations) with looking directly through the eyepiece (n = 20), or with the display of the scope on a video monitor (n = 16). The subjects each then performed 15 Bullard intubations by looking directly through the eyepiece. RESULTS: There was not an overall significant difference in laryngoscopy or intubation times between the groups. When only the first 15 intubations were considered, the laryngoscopy time was shorter in the video group (26 +/- 24) than in the nonvideo group (32 +/- 34; P< 0.04). In the first 15 patients, there were fewer single attempts at intubation (67.9% vs 80.3%; P< 0.002) and more failed intubations (17.2% vs 6.0%; P< 0.0001) in the nonvideo group. CONCLUSIONS: In conclusion, the authors have shown that use of a video camera decreases time for laryngoscopic view and improves success rate when the Bullard laryngoscope is first being taught to experienced clinicians. However, these benefits are not evident as more experience with the Bullard laryngoscope is achieved, such that no difference in skill with the Bullard laryngoscope is discernible after 15 intubations whether a video system was used to teach this technique.
Female↗
The lateralized stroop: a meta-analysis and its implications for models of semantic processing.
The prevailing theory in the literature concerning the lateralization of Stroop effects involves a speed of processing account (see ). Because the left hemisphere (LH) demonstrates an overall advantage relative to the right hemisphere (RH) on most verbal tasks, interference effects are hypothesized to be greater in the LH than in the RH. Inspection of the data, however, reveals that many studies find no difference in magnitude of Stroop interference between the hemispheres. Given findings within the lateralized semantic priming literature, this is not surprising. A meta-analysis on a subset of lateralized Stroop experiments was conducted to determine whether or not the LH produces significantly more interference than the RH in this paradigm. Based on a number of exclusionary criteria, a total of 19 different studies were included, representing a potential 26 effect size estimates of differential interference. The effect size representing interference using congruent conditions as the baseline (d+=.06) reveals that there is no significant difference between the hemispheres in magnitude of the Stroop interference effect. The LH interference effect was d+=.73, which is significant. Likewise, the RH interference effect, d+=.67, was significant. In summary, while there was no significant difference between the hemispheres, each hemisphere, when examined independently, did exhibit significant within hemisphere interference effects. These findings are presented in light of the lateralized semantic priming literature.
Brain↗
Reduced suppression or labile memory? Mechanisms of inefficient filtering of irrelevant information in older adults.
Cognitive aging theories emphasize the decrease in efficiency of inhibitory processes and attention control in normal aging, which, in turn, may result in reduction of working memory function. Accordingly, some of these age-related changes may be due to faster sensory memory decay or to inefficient filtering of irrelevant sensory information (sensory gating). Here, event-related brain potentials and the event-related optical signal were recorded in younger and older adults passively listening to tone trains. To determine whether age differentially affects decay of sensory memory templates over short intervals, trains were separated by delays of either 1 or 5 sec. To determine whether age affects the suppression of responses to unattended repeated stimuli, we evaluated the brain activity elicited by successive train stimuli. Some trains started with a shorter-duration stimulus (deviant trains). Results showed that both electrical and optical responses to tones were more persistent with repeated stimulation in older adults than in younger adults, whereas the effects of delay were similar in the two groups. A mismatch negativity (MMN) was elicited by the first stimulus in deviant trains. This MMN was larger for 1- than 5-sec delay, but did not differ across groups. These data suggest that age-related changes in sensory processing are likely due to inefficient filtering of repeated information, rather than to faster sensory memory decay. This inefficient filtering may be due to, or interact with, reduced attention control. Furthermore, it may increase the noise levels in the information processing system and thus contribute to problems with working memory and speed of processing.
Acoustic Stimulation↗
[Reaction time experiment on absolute or relative functional specialization of the cerebral hemispheres in man].
Lateralized presentations of verbal stimuli yield faster reaction times in the right visual field-left hemisphere, whereas nonverbal stimuli yield faster reaction times in the left visual field-right hemisphere. However, the problem of how lateral asymmetries in response latency are determined is still unsolved. The hypothesis of an absolute functional specialization of the two hemispheres suggests that information presented in the visual field connected with the unspecialized hemisphere has to travel along a less direct pathway, implying a crossing through the forebrain commissures, to reach the processing center. The hypothesis of a relative functional specialization assumes that stimuli are processed by the hemisphere contralateral to the field of presentation but speed of processing varies as a function of hemispheric specialization. The present study tried to find empirical evidence in favor of one of the two hypotheses. Choice reaction times to lateralized verbal stimuli were studied in normal subjects. In half of the trials the subjects had to carry out a concomitant task known to interfere selectively with mechanisms responsible of the organization of the responses of the left hemisphere. Both with and without concomitant task reaction times were significantly faster in the right visual field-left hemisphere. While the concomitant task produced an overall lengthening of reaction time, it did not affect interhemispheric asymmetry. This finding was discussed as evidence in favor of the absolute specialization hypothesis.
Acoustic Stimulation↗
Estimation of temporal resolution of object identification in human vision.
The purpose of the study was to estimate the temporal processing capacity of human object identification under different stimulus conditions. Objects, either facial images or characters, were shown in a rapid sequence on a computer display using a rapid serial visual presentation (RSVP) method. One of the images was a target and the other images were distracters. The task of the observer was to identify the target. A staircase algorithm was used to determine the threshold frequency of image presentation in the RSVP sequence. The threshold frequency was determined as a function of image contrast, size, and mean luminance. The results showed that the threshold frequency, around 10 Hz for faces (100 ms per face) and about 25 Hz for characters (40 ms per character), was independent of contrast and size at medium and high contrast values, medium and large sizes, and high luminances, but decreased at very low contrasts or small sizes and medium or low levels of luminance. Computer simulations with a model, in which temporal integration limited perceptual speed, suggest that the experimentally found difference in processing time for faces and characters is not due to the physical differences of these stimulus types, but it seems that face-specific sites in the brain process facial information slower than object-specific areas process character information. Contrast, size, and luminance affect the signal-to-noise ratio and the temporal characteristics of low-level neural signal representation. Thus, the results suggest that at low contrasts, low luminances and small sizes, the processing speed of object identification is limited by low-level factors, while at high contrasts and luminances, and at large sizes, processing speed is limited by high-order processing stages. Processing speed seems to depend on stimulus type so that for faces processing is slower than for characters.
Algorithms↗
Vasopressin metabolite neuropeptide facilitates simultaneous temporal processing.
Rats were trained on a peak-interval timing procedure in which auditory, tactile, and visual stimuli signaled 3 different fixed-interval schedules (15, 30, and 60 s) that were presented simultaneously in a hierarchical fashion. Administration of vasopressin metabolite neuropeptide [pGlu-Asn-Cys(Cys)-Pro-Arg-Gly-NH2, 0.3 microgram/kg i.p.] had two main effects on performance. With repeated exposure the temporal criterion for each of the intervals shifted leftward on the time scale in a proportional manner, and the probability of attention to each of the intervals increased proportionally. The conclusion is that vasopressin metabolite neuropeptide facilitates simultaneous temporal processing by increasing the speed of mental processes involved in memory storage and divided attention. These results indicate that a major metabolite of arginine vasopressin that is devoid of endocrine and pressor activity can produce facilitation of cognitive processes in animals.
Animals↗