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PubMed1996

Hemispheric independence in word recognition: evidence from unilateral and bilateral presentations.

We compared behavioral laterality effects in a lexical decision task using cued unilateral or bilateral presentations of different stimuli to normal subjects. The goals were to determine the effects of lexical variables on word recognition in each hemisphere under conditions of maximal independence of information processing in the two hemispheres and to assess the degree of residual interhemispheric effects that can still exist then. Bilateral presentations increased hemispheric independence in word recognition, indexed by a significant interaction of response hand with target visual field. Bilateral presentations also selectively impaired word decisions, suggesting that word processing benefits from interhemispheric interactions, whereas nonword processing is done independently in each hemisphere. Indeed, there was a significant congruity effect for word targets only, whereby the wordness of the unattended stimulus affected the speed of processing of attended word targets. Word frequency and regularity affected both hemispheres equally, arguing against the hemispheric interpretation on the dual route model of word recognition. Length affected the processing of nonwords more than words and in the left visual field more than in the right visual field. Taken together, the data support the conclusion that each normal hemisphere can control word recognition independently of the other.

Brain↗

PubMed1997

The direction of retinal motion facilitates binocular stereopsis.

Visual information from binocular disparity and from relative motion provide information about three-dimensional structure and layout of the world. Although the mechanisms that process these cues have typically been studied independently, there is now a substantial body of evidence that suggests that they interact in the visual pathway. This paper investigates one advantage of such an interaction: whether retinal motion can be used as a matching constraint in the binocular correspondence process. Stimuli that contained identical disparity and motion signals but which differed in their fine-scale correlation were created to establish whether the direction, or the speed, of motion could enhance performance in a psychophysical task in which binocular matching is a limiting factor. The results of these experiments provide clear evidence that different directions of motion, but not different speeds, are processed separately in stereopsis. The results fit well with properties of neurons early in the cortical visual pathway which are thought to be involved in determining local matches between features in the two eyes' images.

Depth Perception↗

PubMed2006

[Study on oxidant strengthening photocatalytic degradation of DMF over TiO2 fiber catalyst].

Oxidant strengthening the degradation of DMF aqueous solution was investigated when TiO2 fiber is used as the photocatalyst. When the UV light was absent, ozone per se could not make DMF degrade, which proves that DMF is a stable substance. But ozone could increase obviously photocatalytic degradation rate of DMF in O3/TiO2 (F). Under the same reaction condition, photocatalytic degradation rate and speed of DMF in O3/TiO2 (F) was almost 1.5 times and 2 times higher than that in air/ TiO2 (F) and H2O2/TiO2 (F) respectively. COD analysis showed DMF was almost mineralized completely when the reaction was carried out for 120 min. Through Hinsberg test secondary amine was proved as one of intermediates in the process of DMF photocatalytic degradation. Rise of pH value of reaction solution also showed that amine was produced in the photocatalytic reaction process. Degradation speed of DMA in O3/TiO2 (F) was higher than that in air/TiO2 (F). The increasing degradation rate and speed of DMF was mainly caused by fast degradation of secondary amine in the process of DMF photocatalytic degradation in O3/TiO2 (F).

Biodegradation, Environmental↗

PubMed1978

[Interhemispheric relations in the process of visual perception in schizophrenic patients].

The purpose of the performed study was to compare the time of visual stimuli perception for different hemispheres in normals and in schizophrenic patients. In normals there was a certain asymmetry in the speed of perception of letter stimuli between the right and left hemispheres. It was established, that in the right hemisphere there was a more rapid perception of the letters as compared to the left one. In schizophrenic patients there is no interhemispheric differences in the time of perception, owing to the fact that the right hemisphere loses the advantage in speed of processing visual information. The author makes an assumption of the possible role of disturbed activity of the right hemisphere in the psychopathological symptomatology.

Adolescent↗

PubMed2001

Supervisory attentional system in nonamnesic alcoholic men.

BACKGROUND: Many studies have shown that recently detoxified alcoholic persons perform poorly on tasks thought to be sensitive to frontal lobe damage, supporting the hypothesis that the frontal lobes are highly vulnerable to chronic alcohol consumption. However, it appeared that most of the executive tasks used in these studies also involved nonexecutive components, and these tasks had been shown to be impaired as a result of nonfrontal lobe lesions. In this study, we examined further the "frontal lobe vulnerability" hypothesis using executive tasks, proved to be associated with frontal lobe functioning, that allowed us to distinguish the relative importance of executive and nonexecutive processes. METHOD: Thirty recently detoxified asymptomatic male alcoholic inpatients and 30 control subjects were tested for planning, inhibition, rule detection, and coordination of dual task, as well as the speed of processing and nonexecutive functions (such as short-term memory storage). RESULTS: Alcoholics performed worse than controls in almost all tasks assessing executive functions. However, they were not slower than the controls and showed normal results for nonexecutive functions. CONCLUSIONS: Chronic alcohol consumption seems to be associated with severe executive function deficits, which are still present after a protracted period of alcohol abstinence. These data support the idea that the cognitive deficits in recently detoxified sober alcoholic subjects are due, at least partly, to frontal lobe dysfunctioning.

Adult↗

PubMed2003

A directional acoustic array using silicon micromachined piezoresistive microphones.

The need for noise source localization and characterization has driven the development of advanced sound field measurement techniques using microphone arrays. Unfortunately, the cost and complexity of these systems currently limit their widespread use. Directional acoustic arrays are commonly used in wind tunnel studies of aeroacoustic sources and may consist of hundreds of condenser microphones. A microelectromechanical system (MEMS)-based directional acoustic array system is presented to demonstrate key technologies to reduce the cost, increase the mobility, and improve the data processing efficiency versus conventional systems. The system uses 16 hybrid-packaged MEMS silicon piezoresistive microphones that are mounted to a printed circuit board. In addition, a high-speed signal processing system was employed to generate the array response in near real time. Dynamic calibrations of the microphone sensor modules indicate an average sensitivity of 831 microV/Pa with matched magnitude (+/-0.6 dB) and phase (+/-1 degree) responses between devices. The array system was characterized in an anechoic chamber using a monopole source as a function of frequency, sound pressure level, and source location. The performance of the MEMS-based array is comparable to conventional array systems and also benefits from significant cost savings.

Journal Article↗

PubMedDate not supplied

Neural basis of saccade target selection.

Saccade target selection must be understood in relation to the obvious fact that vision naturally occurs in a continuous cycle of fixations interrupted by gaze shifts. The guidance of eye movements requires information about what is where in the visual field. The identities of objects are derived from their visible features. Single neurons in the visual system represent the presence of specific features by the level of activation; the reliability of the discriminating signal from single neurons varies over time. Each point in the visual field is represented by many populations of neurons activated by all types of features. Topographic representations are found throughout the visual and oculomotor systems; neighboring neurons tend to represent similar visual field locations or saccades. Selecting one out of many stimuli to which to direct gaze requires comparing stimulus attributes across the visual field. The existence of retinotopic maps of the visual field makes possible local interactions to implement such comparisons /41/. For example, a lateral inhibition network can extract the location of the most conspicuous stimulus in the visual field /30,40,81/. Coordinated with this parallel visual processing is activation in structures responsible for producing the movement such as FEF and the superior colliculus. A saccade is produced when the neurons at one location within the motor maps become sufficiently active. One job of visual processing, then, is to ensure that only one site within a movement map becomes activated. This is done when the neurons signalling the location of the desired target develop enhanced activation while the neurons responding to other locations are attenuated. Saccade target selection often converts an initially ambiguous pattern of neural activation into a pattern that reliably signals one target location. The ambiguity may be reduced through prior knowledge of the likely target location or identity, and extraretinal signals reflecting such expectations can modulate the responsiveness of afferent visual neurons. Specifying the metrics of a saccade and triggering the movement are coordinated but dissociable processes. Speed-accuracy trade-offs can thereby be produced allowing the visuomotor system to produce a saccade that is inaccurate because it is premature relative to the target selection process. While there are many gaps in our knowledge, the questions to ask seem reasonably clear. Because saccade target selection involves visual processing and eye movement programming combined with mnemonic influences, only continued experimental ingenuity will disentangle the various and variable contributions of individual neurons.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed2006

Gene expression profiling as novel tool in experimental asthma research.

With the advances achieved in decoding of the genetic structures of species and the novel possibilities of simultaneous measurements of the regulation of all genes of a given tissue, the last 10 years have seen a massive increase of our knowledge about genetic regulation of diseases. Additionally, the possibilities to control transcriptional processes within the cells will speed up the process of disentangling the various pathways leading to disease.

Animals↗

PubMed2005

Asymptotic prey profitability drives star-nosed moles to the foraging speed limit.

Foraging theory provides models for predicting predator diet choices assuming natural selection has favoured predators that maximize their rate of energy intake during foraging. Prey profitability (energy gained divided by prey handling time) is an essential variable for estimating the optimal diet. Time constraints of capturing and consuming prey generally result in handling times ranging from minutes to seconds, yet profitability increases dramatically as handling time approaches zero, providing the potential for strong directional selection for increasing predator speed at high encounter rates (tiny increments in speed increase profitability markedly, allowing expanded diets of smaller prey). We provide evidence that the unusual anatomical and behavioural specializations characterizing star-nosed moles resulted from progressively stronger selection for speed, allowing the progressive addition of small prey to their diet. Here we report handling times as short as 120 ms (mean 227 ms) for moles identifying and eating prey. 'Double takes' during prey identification suggest that star-nosed moles have reached the speed limit for processing tactile information. The exceptional speed of star-nosed moles, coupled with unusual specializations for finding and eating tiny prey, provide new support for optimal foraging theory.

Animals↗

PubMed2004

Syntactic processing with aging: an event-related potential study.

To assess age-related changes in simple syntactic processing with normal aging, event-related brain potentials (ERPs) elicited by grammatical number violations as individuals read sentences for comprehension were analyzed. Violations were found to elicit a P600 of equal amplitude and latency regardless of an individual's age. Instead, advancing age was associated with a change in the scalp distribution of the P600 effect, being less asymmetric and more frontal (though still with a parietal maximum) in older than younger adults. Our results thus show that the brain's response to simple syntactic violations, unlike those reported for simple binary categorizations and simple semantic violations, is neither slowed nor diminished in amplitude by age. At the same time, the brain's processing of these grammatical number violations did engage at least somewhat different brain regions as a function of age, suggesting a qualitative change rather than any simple quantitative change in speed of processing.

Adolescent↗

PubMed2004

Annotation: Development of facial expression recognition from childhood to adolescence: behavioural and neurological perspectives.

BACKGROUND: Intact emotion processing is critical for normal emotional development. Recent advances in neuroimaging have facilitated the examination of brain development, and have allowed for the exploration of the relationships between the development of emotion processing abilities, and that of associated neural systems. METHODS: A literature review was performed of published studies examining the development of emotion expression recognition in normal children and psychiatric populations, and of the development of neural systems important for emotion processing. RESULTS: Few studies have explored the development of emotion expression recognition throughout childhood and adolescence. Behavioural studies suggest continued development throughout childhood and adolescence (reflected by accuracy scores and speed of processing), which varies according to the category of emotion displayed. Factors such as sex, socio-economic status, and verbal ability may also affect this development. Functional neuroimaging studies in adults highlight the role of the amygdala in emotion processing. Results of the few neuroimaging studies in children have focused on the role of the amygdala in the recognition of fearful expressions. Although results are inconsistent, they provide evidence throughout childhood and adolescence for the continued development of and sex differences in amygdalar function in response to fearful expressions. Studies exploring emotion expression recognition in psychiatric populations of children and adolescents suggest deficits that are specific to the type of disorder and to the emotion displayed. CONCLUSIONS: Results from behavioural and neuroimaging studies indicate continued development of emotion expression recognition and neural regions important for this process throughout childhood and adolescence. Methodological inconsistencies and disparate findings make any conclusion difficult, however. Further studies are required examining the relationship between the development of emotion expression recognition and that of underlying neural systems, in particular subcortical and prefrontal cortical structures. These will inform understanding of the neural bases of normal and abnormal emotional development, and aid the development of earlier interventions for children and adolescents with psychiatric disorders.

Adolescent↗

PubMed2003

Requirements for submission of labeling for human prescription drugs and biologics in electronic format. Final rule.

The Food and Drug Administration (FDA) is amending its regulations governing the format in which certain labeling is required to be submitted for review with new drug applications (NDAs), certain biological license applications (BLAs), abbreviated new drug applications (ANDAs), supplements, and annual reports. The final rule requires that certain labeling content be submitted electronically in a form that FDA can process, review, and archive. Submitting the content of labeling in electronic format will simplify the drug labeling review process and speed up the approval of labeling changes.

Biological Products↗

PubMed2001

The neuropsychology and neuroanatomy of bipolar affective disorder: a critical review.

UNLABELLED: Bearden CE, Hoffman KM, Cannon TD. The neuropsychology and neuroanatomy of bipolar affective disorder: a critical review. Bipolar Disord 2001: 3: 106 150. C Munksgaard, 2001 OBJECTIVES: To present a comprehensive review of the existing neuropsychological and neuroimaging literature on bipolar affective disorder. This review critically evaluates two common conceptions regarding the neuropsychology of bipolar disorder: 1) that, in contrast to schizophrenia, bipolar affective disorder is not associated with general cognitive impairment independent of illness episodes, and 2) relative right hemisphere (RH) dysfunction is implicated in bipolar illness patients, supported by reports of relatively greater impairment in visuospatial functioning, lateralization abnormalities, and mania secondary to RH lesions. METHODS: The major computerized databases (Medline and PSYCInfo) were consulted in order to conduct a comprehensive, integrated review of the literature on the neuropsychology and neuroanatomy of bipolar disorder. Articles meeting specified criteria were included in this review. RESULTS: In a critical evaluation of the above notions, this paper determines that: 1) while there is little evidence for selective RH dysfunction, significant cognitive impairment may be present in bipolar illness, particularly in a subgroup of chronic, elderly or multiple-episode patients, suggesting a possible toxic disease process, and 2) the underlying functional correlate of these cognitive deficits may be white matter lesions ('signal hyperintensities') in the frontal lobes and basal ganglia, regions critical for executive function, attention, speeded information processing, learning and memory, and affect regulation. While this hypothesized neural correlate of cognitive impairment in bipolar disorder is speculative, preliminary functional neuroimaging evidence supports the notion of frontal and subcortical hypometabolism in bipolar illness. CONCLUSIONS: The etiology of the structural brain abnormalities commonly seen in bipolar illness, and their corresponding functional deficits, remains unknown. It is possible that neurodevelopmental anomalies may play a role, and it remains to be determined whether there is also some pathophysiological progression that occurs with repeated illness episodes. More research is needed on first-episode patients, relatives of bipolar probands, and within prospective longitudinal paradigms in order to isolate disease-specific impairments and genetic markers of neurocognitive function in bipolar disorder.

Adult↗

PubMed2002

Comparison of analog and digital Fourier transforms in medical image analysis.

The effectiveness and limitations of medical image processing using analog and digital methods are studied. Several types of errors introduced during the image processing are analyzed. For the analog optical Fourier transform, errors are introduced by the vignetting effect and lens aberration. For the digital Fourier transform, errors are introduced by the aliasing effect and the band limit. To compare the results obtained by the two techniques, a set of x-ray images was processed both optically and digitally. The former was achieved by an optical system containing a large Fourier telephoto lens and the latter by a personal computer using a Fourier transform algorithm. The veracity of both the optical and digital Fourier spectra is analyzed. Our results indicate that the optical method has high speed due to parallel processing. High veracity can be achieved in high frequency regions by using an optimal optical system. In comparison, the digital method has the advantages of high processing precision and programmability, but has low processing speed. The comparison of the two different techniques presented in this article can provide a basis for selection of the processing method in different clinical settings. Even with today's fast computers, the optical method is still suitable for many clinical applications. The best choice lies in an analog-digital combination.

Algorithms↗

PubMed1992

A developmental event-related potential study of picture matching in children, adolescents, and young adults: a replication and extension.

Event-related potentials were recorded in a developmental study of picture matching using an adaptation of Posner's (1978) letter-matching tasks. Subjects ranging in age from 6-39 were asked to decide whether two line drawings, presented sequentially, were the same or different on the basis of physical (physical identity), nominal (name identity), or categorical (category identity) criteria. The amplitude of a negativity at 400 ms (Neg400) increased as the number of dimensions on which the two line drawings differed increased. This effect held for all age groups, and was interpreted as reflecting the degree of semantic and/or physical relationship between the two pictures. However, one finding for Neg400 did suggest a qualitative difference in processing mode between the younger and older subjects. Both Neg400 and P3b latencies showed highly significant linear age trends, decreasing with increasing age. These age-related changes were interpreted as demonstrating quantitative speed of processing differences among age groups. The latencies of both Neg400 and P3b increased as the matching criteria became more complex. Moreover, P3b latency increased as the number of dimensions on which the two pictures differed increased, and this did not interact with age. Although both Neg400 and P3b showed age-related changes in scalp distribution, the fact that each was related to the experimental variables in similar fashion in all age groups suggested that they were homologous components across the age range studied. Taken as a whole, the data support continuity of information processing during these tasks across a wide age range.

Adolescent↗

PubMed2004

Lab order to results in 16 minutes? You heard right!

Six Sigma, an approach to performance improvement that originated in the manufacturing sector, is being applied readily to the ED environment. Turnaround time for ED lab specimens is reduced by 30 minutes. Many ED processes have multiple steps. Six Sigma approach identifies subprocesses for targeted improvement. Data-heavy analysis eliminates the emotional component of problem solving. Bedside nurses and phlebotomists all are equipped with pagers to speed the process of getting blood samples to the lab.

Efficiency, Organizational↗

PubMed1999

[Epilepsy and learning: a neuropsychological approach].

INTRODUCTION: The quality of life of an epileptic patient largely depends on the interplay of the control of the convulsive crises and the degree to which higher mental functions are affected. Some types of epilepsy lead to mental retardation during development and with others the basic cerebral mechanisms for processing data are damaged and this may lead to transient or permanent cogniscitive deterioration. DEVELOPMENT: There are certain important clinical factors such as the site of the discharge regarding the lobe, hemisphere, type of cerebral area involved and the age of the patient. We describe the clinical features of each type of epilepsy with respect to focal or generalized involvement. The subclinical effects of continuous discharges affects processing in the areas involved and therefore intellectual function, thus leading to a secondary learning disorder. The neuropsychological tests used in investigation of higher cerebral functions in epilepsy include, in general, tests to assess speed of processing, attention, memory, reasoning and visuospacial ability and frontal executive functions. CONCLUSIONS: These tests should be sufficiently sensitive so as to detect minimal changes in the state of the illness, the time elapsed and the medication given. Anticonvulsant drugs may themselves cause changes in mental functions. There may often be mixed neurocognitive behaviour depending on the drug used. There may also be transient cognitive deterioration.

Anticonvulsants↗

PubMed2001

Ribosome display and affinity maturation: from antibodies to single V-domains and steps towards cancer therapeutics.

Protein affinity maturation using molecular evolution techniques to produce high-affinity binding proteins is an important step in the generation of reagents for cancer diagnosis and treatment. Currently, the most commonly used molecular evolution processes involve mutation of a single gene into complex gene repertoires followed by selection from a display library. Fd-bacteriophage are the most popular display vectors, but are limited in their capacity for library presentation, speed of processing and mutation frequency. Recently, the potential of ribosome display for directed molecular evolution was recognised and developed into a rapid and simple affinity selection strategy using ribosome complexes to display antibody fragments (scFv). Ribosome display and selection has the potential to generate and display large libraries more representative of the theoretical optima for naïve repertoires (10(14)). Even more important is the application of ribosome display for the affinity maturation of individual proteins by rapid mutation and selection cycles. These display strategies can apply to other members of the immunoglobulin superfamily; for example single V-domains which have an important application in providing specific targeting to either novel or refractory cancer markers. We discuss the application of ribosome display and selection in conjunction with variable domain (CTLA-4) libraries as the first step towards this objective and review affinity maturation strategies for in vitro ribosome display systems.

Amino Acid Sequence↗