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PubMed2005

Cognitive impairments in the locked-in syndrome: a case report.

No neuropsychologic studies have been reported that assess cognitive functioning in survivors of locked-in syndrome (LIS) due to purely pontine lesions and then document the process of recovery by serial testing over a lengthy period. A previously well man in his early thirties was admitted to the hospital with progressive stroke symptoms and signs. Investigations showed occlusion of the basilar artery and acute infarction of the pons, including basis and tegmentum. Despite thrombolysis, he had persisting clinical features of the LIS. He had minimal change during the first month but then slowly improved. Recovery continued gradually, and he was discharged home 7 months after stroke; at this time he was ambulating with a cane, was mildly dysarthric, was able to swallow foods of modified consistency, and was independent in all self-care activities. Neuropsychologic testing, done 6 months after stroke, showed noteable cognitive impairments. These included mild difficulties with attention and concentration, significant reduction in speed of processing, moderate impairment of perceptual organization skills, mild inefficiencies in new learning of verbal information, and a moderate reduction in executive skills. Pathologic laughing and crying were also noted. There was progressive improvement in most areas of physical and cognitive functioning until at least 2 years after stroke. Neuropsychologic testing in this patient suggests that the LIS may be associated with impairments of higher-level cognitive functioning.

Adult↗
PubMed1994

Endoproteolytic processing of proopiomelanocortin and prohormone convertases 1 and 2 in neuroendocrine cells overexpressing prohormone convertases 1 or 2.

AtT-20 mouse corticotrope tumor cell lines overexpressing the prohormone convertases PC1 or PC2 were established and used to examine prohormone and prohormone convertase biosynthetic processing. On a molar basis, wild-type AtT-20 cells synthesize about 20% as much PC1 as the endogenous prohormone, proopiomelanocortin (POMC). Kinetic, oligosaccharide, and temperature blockade analyses established that proPC1 is converted to PC1 in the endoplasmic reticulum at a rate independent of the level of PC1 or PC2 expression. In contrast, proPC2 is converted to PC2 primarily in a post-trans-Golgi compartment. PC1 is further shortened from its COOH-terminal end in a post-trans-Golgi compartment in a step that is accelerated at higher levels of PC1 expression, but unaltered by PC2 overexpression. The initial steps in POMC processing are speeded up by overexpression of PC1, and overexpression of PC1 leads to more extensive cleavage of POMC to smaller products. However, even when the rate of PC1 synthesis exceeds that for POMC by 2-fold, PC1 does not cleave the Lys-Lys or Arg-Lys bonds cleaved upon overexpression of PC2.

Animals↗
PubMed1998

Synthetic Analysis for Extracting Information on Soil Salinity Using Remote Sensing and GIS: A Case Study of Yanggao Basin in China

/ This paper reports the experience of extracting information on the salinity of soil and offers a method of synthetic analysis. The experimental areas for analysis are located in Yanggao Basin, Shanxi Province, China. The types of soil are mainly meadow soil and salinized meadow soil. The method of synthetic analysis of salinity uses a geographic information system (GIS) as a tool, building a basic saltwater analysis model of saline soil and adjusting the result with expert experience after computer processing. The method of feature extraction has been used for remotely sensed data. An optimum combination of features has been determined and, after comparing several combinations in the Yanggao region, an improved result has been obtained after Kauth-Thomas (K-T) transformation. For precise quantitative analysis of the salinization, not only Thematic Mapper (TM) remote sensing data, but also two forms of non-remote-sensing data are needed: depth of groundwater and mineralization rate of groundwater according to the theory of genesis of soil. For the analysis of synthetic compounded multisources, a generalized Bayes classification is used after overlay, matching, and related coefficients have been determined. On the premise that various information sources are independent, global membership functions with probability are used to combine various pieces of information in order to apply them directly to the pixels and classifications of soil salinity. The experiment indicates that this analytical method is sound because of the increased speed of processing and its simplicity and improved precision of classification of salinity. Finally, it is necessary to examine and adjust the factors using expert intelligence. The experiment shows that synthetic analysis using the geographic information system can raise the precision of quantitative analysis of salinity, which has advantages for environmental monitoring and management.KEY WORDS: Salinity; Remote sensing; Thematic Mapper; Geographic information system; Classification

Journal Article↗
PubMed1992

The effects of hypoxia on auditory reaction time and P300 latency.

A predominant feature of hypoxia is that it slows information processing. Evidence is accumulating that early visual mechanisms are an important locus of this slowing. Audition is believed to be insensitive to hypoxia, implying relatively less slowing with auditory stimuli. Subjects breathed air or a low oxygen mixture (65% arterial oxyhemoglobin saturation) while RT (reaction time) and the EEG were collected to oddball binaural tone pips at 500 Hz, 1000 Hz, and 4000 Hz. Hypoxia slowed RT and the event-related brain potential P300 in a correlated manner and by an identical amount that was generally independent of frequency. On the assumption that P300 indexes the time to evaluate a stimulus and RT indexes this time plus the time to select and execute a response, stimulus evaluation is implicated as a major locus of slowing in this experiment. The amount of slowing was comparable to that found previously with RT and P300 to visual stimuli. It may be that audition is more sensitive to hypoxia than is currently believed, at least where the speed of processing is concerned.

Adult↗
PubMed1990

A review of the CLIP system for the quantitative analysis of two-dimensional electrophoresis gels.

This paper reviews the CLIP image processing system for the complete analysis of two-dimensional electrophoresis images. The analysis problem for two-dimensional gel images can be broken down into three issues: segmentation of individual gel images, alignment and comparison of pairs of gel images, and information storage and retrieval. This paper describes these problems and reviews how the CLIP system handles each of them. Segmentation is the location and isolation of each protein spot on an individual gel image and also the extraction of individual spot data such as position, area and volume. There are three basic stages: background field correction, noise filtering, spot detection and information extraction. Alignment and comparison of gel images involves matching protein spots between two gels. This can be quite difficult because there is not a simple relationship which can transform one gel image onto another. The database issues concern storing all the information which has been obtained from the above operations such that retrieval of this information can be readily performed. The advantage of the CLIP system over others is speed of processing. CLIP series computers use one processor for every pixel of the camera image such that image processing algorithms run in parallel. The main disadvantage is in the cost of these machines. With the declining trend in the cost of parallel processors, these machines will become more and more viable alternatives. This papers reviews the algorithms for the analysis of two-dimensional gels. It is shown that CLIP is flexible enough to perform more than one type of algorithm for a particular operation.

Algorithms↗
PubMed2004

Amygdala responses to fearful and happy facial expressions under conditions of binocular suppression.

The human amygdala plays a crucial role in processing affective information conveyed by sensory stimuli. Facial expressions of fear and anger, which both signal potential threat to an observer, result in significant increases in amygdala activity, even when the faces are unattended or presented briefly and masked. It has been suggested that afferent signals from the retina travel to the amygdala via separate cortical and subcortical pathways, with the subcortical pathway underlying unconscious processing. Here we exploited the phenomenon of binocular rivalry to induce complete suppression of affective face stimuli presented to one eye. Twelve participants viewed brief, rivalrous visual displays in which a fearful, happy, or neutral face was presented to one eye while a house was presented simultaneously to the other. We used functional magnetic resonance imaging to study activation in the amygdala and extrastriate visual areas for consciously perceived versus suppressed face and house stimuli. Activation within the fusiform and parahippocampal gyri increased significantly for perceived versus suppressed faces and houses, respectively. Amygdala activation increased bilaterally in response to fearful versus neutral faces, regardless of whether the face was perceived consciously or suppressed because of binocular rivalry. Amygdala activity also increased significantly for happy versus neutral faces, but only when the face was suppressed. This activation pattern suggests that the amygdala has a limited capacity to differentiate between specific facial expressions when it must rely on information received via a subcortical route. We suggest that this limited capacity reflects a tradeoff between specificity and speed of processing.

Adult↗
PubMed2004

Event-related brain potentials reveal anomalies in temporal processing of faces in autism spectrum disorder.

BACKGROUND: Individuals with autism exhibit impairments in face recognition, and neuroimaging studies have shown that individuals with autism exhibit abnormal patterns of brain activity during face processing. The current study examined the temporal characteristics of face processing in autism and their relation to behavior. METHOD: High-density event-related brain potentials (ERPs) were recorded to images of faces, inverted faces, and objects from 9 individuals with autism spectrum disorder (15-42 years old) and 14 typical individuals (16-37 years old). RESULTS: With respect to a face-sensitive ERP component (N170), individuals with autism exhibited longer N170 latencies to faces than typical individuals but comparable latencies to objects. Typical individuals exhibited longer N170 latencies to inverted as compared to upright faces, whereas individuals with autism did not show differences in N170 latency to upright versus inverted faces. Neural speed of face processing, as reflected in N170 latency, correlated with performance on a face recognition task for individuals with autism. CONCLUSIONS: These data provide evidence for slowed neural speed of face processing in autism and highlight the role of speed of processing in face processing impairments in autism.

Adolescent↗
PubMed1985

Interhemispheric collaboration in response to simultaneous bilateral input.

Two experiments tested whether processing is speeded when inputs are divided between the hemispheres rather than projected to a single hemisphere. Bilateral (bihemispheric) vs unilateral (single hemisphere) word pairs were tachistoscopically presented. Subjects responded when the words semantically matched. Irrespective of distance, visual angle and compatibility with reading biases, bilateral/bihemispheric performance was as fast as the better of the two individual unilateral/single hemisphere conditions and faster than their average. This pattern occurred only at the beginning of each experiment. With practice, performance significantly improved in the single but not the bihemispheric conditions. The excellent initial performance during the bihemispheric condition and its lack of improvement with practice are discussed with reference to models of interhemispheric collaboration.

Adolescent↗
PubMed1990

The effect of visual angle on global and local reaction times depends on the set of visual angles presented.

It has been shown that there is a transition from a global to a local advantage in reaction time as visual angle increases (Kinchla & Wolfe, 1979), and it has been assumed that this transition reflects lower level (e.g., retinal) processes. In three experiments, we examined whether higher level (e.g., attentional) processes play a role in this transition. In each experiment, subjects received a different stimulus set in each of two blocks of trials. In Experiment 1, stimuli subtending 1.5 degrees, 3 degrees, 4.5 degrees, or 6 degrees of visual angle vertically (small-stimuli set) were randomly presented in one block, while the other block consisted of random presentations of 3 degrees, 6 degrees, 9 degrees, or 12 degrees stimuli (large-stimuli set). The subjects' task was to identify targets that appeared randomly at either the local or the global level. It was found that the transition from a global to a local reaction-time advantage took place at a larger visual angle for the large-stimuli set than for the small-stimuli set. The same effects of stimulus set were found in Experiment 2, in which the small-stimuli set included 1.5 degrees, 3 degrees, or 6 degrees stimuli while the large-stimuli set included 3 degrees, 6 degrees, or 9 degrees stimuli. In Experiment 3, eye position was monitored to rule out the possibility that subjects adopted different fixation strategies depending on which stimulus set was being presented. The findings suggest that attention plays a major role in determining the relative speed of processing of local-and global-level information.

Aged↗
PubMed2006

Fast vector quantization algorithms based on nearest partition set search.

A fast search method for vector quantization is proposed in this paper. It makes use of the fact that in the generalized Lloyd algorithm (GLA) a vector in a training sequence is either placed in the same minimum distance partition (MDP) as in the previous iteration or in a partition within a very small subset of partitions. The proposed method searches for the MDP for a training vector only in this subset of partitions plus the single previous MDP. As the size of this subset is much smaller than the total number of codevectors, the search process is speeded up significantly. The creation of the subset is essential, as it has a direct effect on the improvement in computation time of the proposed method. The schemes that create the subset efficiently have been proposed. The proposed method generates a codebook identical to that generated using the GLA. It is simple and requires only minor modification of the GLA and a modest amount of additional memory. The experimental results show that the computation time of codebook training was improved by factors from 6.6 to 50.7 and from 5.8 to 70.4 for two test data sets when codebooks of sizes from N = 16 to 2048 were trained. The proposed method was also combined with an earlier published method to further improve the computation time.

Algorithms↗
PubMed2004

Effects of acute and repeated administration of a cholinesterase inhibitor on timing behaviour.

It has been hypothesised that a leftward shift in the response distribution obtained in the peak interval (PI) procedure is a characteristic of cognitive enhancement in which mental processes are speeded. Metrifonate, a cholinesterase inhibitor with reported cognitive enhancing properties in many animal models of learning and memory, was tested in the PI procedure. Acute administration of 3 and 60 mg/kg but not 1 and 30 mg/kg in fully trained rats shifted the response distribution to the right, whereas subchronic administration of 10, 30 or 50 mg/kg during task acquisition had no effect on timing behaviour. On the basis of the present data, it can be concluded that the effects of a cognition enhancer in the PI procedure cannot be predicted from the scalar expectancy theory (SET). Furthermore, SET does not appear to be an appropriate tool for analysing the acquisition of timing behaviour.

Animals↗
PubMed1998

Neuropsychological outcomes of traumatic brain injury and substance abuse in a New Zealand prison population.

Fifty subjects with a history of traumatic brain injury (TBI) and/or substance use, completed neuropsychological measures of short and long term verbal and visual memory, information processing, motor speed and co-ordination, executive functioning, and malingering. All subjects performed below norms on tests of verbal memory and verbal abstract thinking, but overall no differences were found due to either severity of TBI or level of substance use. Maori subjects obtained the lowest scores on tests of verbal ability, but also reported higher rates of TBI and substance use, which is presumed to account for this result. In conclusion, prison populations seem to have disproportionately high rates of TBI, recurrent TBI, and substance use, compared to the general population. Further, there are a group of individuals who have experienced both TBI and substance abuse, with associated impairments in verbal memory and learning, abstract thinking, and who report problems with general memory and socialization. These difficulties may affect functioning both in prison and following release.

Adult↗
PubMed2026

Comparing trajectories of cognitive functioning in treatment-resistant and non-resistant depression: a multicentre linear mixed-effects analysis.

BACKGROUND: Impaired cognitive functioning is a severe symptom in major depressive disorder (MDD). Recent evidence suggests it may be a central characteristic in its treatment resistant form (TRD), potentially constituting a clinical marker for treatment resistance and a target amenable to intervention. To date, cognitive functioning in TRD remains poorly understood and longitudinal investigations are scarce. METHODS: This observational prospective cohort study, including 320 patients diagnosed with MDD from the multicentre PROMPT study, examined differences in cognitive functioning between 118 TRD and 202 non-TRD patients over a period of twelve weeks in a real-world setting, using linear mixed modelling. Patients that failed to respond to at least two prior antidepressants trials at baseline were classified as TRD. RESULTS: TRD patients showed significantly poorer baseline performances than non-TRD patients in attention/processing speed (β = -0.45; 95%CI[-0.70, -0.19]; FDR-p = 0.003) and verbal memory (β = -0.45; 95%CI[-0.72, -0.18]; FDR-p = 0.003). Significant time × group interactions were observed in motor speed and verbal fluency tasks. Post-hoc-analyses revealed stagnation in TRD patients and significant improvement in non-TRD patients. Across all other tasks improvement was observed in both groups, and random effects showed large heterogeneity between patients, indicating notable individual differences in cognitive performances. CONCLUSIONS: The results suggest distinct recovery patters between non-TRD and TRD patients, and diminished functioning in TRD patients at the domain level. However, intact and diminished performances likely occur in both groups, warranting further investigation of cognitive heterogeneity. These short-term findings highlight the need for more comprehensive longitudinal research on cognition in TRD.

Humans↗
PubMed1999

A standardized method of identification of raw and heat-processed fish by urea isoelectric focusing: a collaborative study.

A urea-isoelectric focusing (urea-IEF) method of identifying fish species in processed fishery products was investigated as an interlaboratory collaborative study. The technique was optimized with respect to (i) protein extraction conditions, composition of the extraction solution (urea and SDS solutions), determination of protein concentrations of the fish extracts (five tested methods); (ii) nature of gel (with carrier ampholytes and Immobilines), conditions of rehydration of commercial dry gels, urea concentration; (iii) staining conditions, Coomassie blue and silver staining. The results of various experiments were compared to select the most appropriate methodology, with respect to the discrimination power of differentiating species with the minimal influence of heat processing, reproducibility, speed, and ease of application. The method recommended meets the requirements of food control and customs laboratories.

Fish Products↗
PubMed2000

Dehydroepiandrosterone (DHEA) supplementation for cognition and well-being.

BACKGROUND: In view of the theoretical rationale for beneficial effects of DHEA and DHEAS in aging and dementia, we believe it is timely to undertake a thorough investigation of well-conducted studies in this area. This will provide a basis for confirmation of any effect of DHEA/S administration in humans, in large-scale and properly controlled trials, which would evaluate effective dosage, acceptable route and duration of administration and side effect profiles. This is especially pertinent at this time as DHEA is currently being sold in large quantities in health food stores, particularly in the USA. In some cases the recommended dose is different for men and women (50mg/day for men and 25mg/day for women) and the basis for this recommendation needs to be explored. OBJECTIVES: To establish whether administration of DHEA, or its sulphate, DHEAS, improves psychological well-being and/or improves cognitive function or reduces the rate of decline of cognitive function in older adults or in individuals with dementia. SEARCH STRATEGY: All available electronic databases, hand searched journals, personal communications and conference abstracts were searched for randomised controlled trials of DHEA in well-being and cognition. The total yield from searching was 415 and the detailed breakdown is given in the body of this review. SELECTION CRITERIA: All relevant randomised controlled trials of DHEA or DHEAS were considered for inclusion in the review. Studies where groups are matched, rather than randomised, were also considered. DATA COLLECTION AND ANALYSIS: Data for the specified outcomes were independently extracted by two reviewers (FAH & JvN) and cross-checked. Any discrepancies were discussed and resolved. Where possible and appropriate, data were pooled and the mean differences estimated. MAIN RESULTS: The published DHEA trials fall into 2 categories: 1. four German studies in which DHEA was administered for a period of two weeks or less; 2. a USA study in which DHEA was administered for three months. Well-being was assessed in both sets of studies and a significant improvement was reported in the longer duration USA study, while no effect was reported in the shorter duration studies. The USA study used an open-ended questionnaire for self-assessment of well-being and stated that 67% of men and 82% of women reported enhanced well-being on DHEA compared with placebo. There was no significant change on an analogue measure of libido. The German studies assessed mood and well-being with a number of standardised scales and reported no significant effects of DHEA on any of them. Only the German studies examined performance on cognitive tests, i.e. memory, verbal fluency, speed of processing, etc. They reported no significant benefit of DHEA. REVIEWER'S CONCLUSIONS: The data at present offer limited support for improvement in a sense of well-being following DHEA treatment. This effect was reported only in the longer-term study which used a crude measure of well-being. The data offer no support at present for an improvement in memory or other aspects of cognitive function following DHEA treatment, although cognitive function was only measured in the short-duration trials. In view of the growing public enthusiasm for DHEA supplementation, particularly in the USA, it is clear that high-quality trials need to be undertaken in older adults, in which (a) the duration of DHEA treatment is in excess of two weeks, (b) the number of participants is large enough to detect effects if they exist, and (c) the outcome measures include validated scales for assessment of mood and well-being, and objective tests of cognitive function. Recently, studies of DHEA supplementation in clinical depression and Alzheimer's Disease have been completed in the USA. As soon as the results are available these studies will be reviewed. Currently, two trials (in France and the USA) in normal elderly are in progress.

Adult↗
PubMed2006

Impaired visual search in drivers with Parkinson's disease.

OBJECTIVE: To assess the ability for visual search and recognition of roadside targets and safety errors during a landmark and traffic sign identification task in drivers with Parkinson's disease (PD). METHODS: Seventy-nine drivers with PD and 151 neurologically normal older adults underwent a battery of visual, cognitive, and motor tests. The drivers were asked to report sightings of specific landmarks and traffic signs along a four-lane commercial strip during an experimental drive in an instrumented vehicle. RESULTS: The drivers with PD identified significantly fewer landmarks and traffic signs, and they committed more at-fault safety errors during the task than control subjects, even after adjusting for baseline errors. Within the PD group, the most important predictors of landmark and traffic sign identification rate were performances on Useful Field of View (visual speed of processing and attention) and Complex Figure Test-Copy (visuospatial abilities). Trail Making Test (B-A), a measure of cognitive flexibility independent of motor function, was the only independent predictor of at-fault safety errors in drivers with PD. INTERPRETATION: The cognitive and visual deficits associated with PD resulted in impaired visual search while driving, and the increased cognitive load during this task worsened their driving safety.

Aged↗
PubMed1986

Influence of translocation track on the motion of intra-axonally transported organelles in human nerve.

The mechanism by which organelles are transported bidirectionally in axoplasm is still unknown; however, evidence of a key role for microtubules in many nonmammalian models has been established. We have observed common or shared tracks within the axoplasm of human nerves along which multiple organelles of varying size and shape are bidirectionally transported. Organelles traveling anterogradely and retrogradely were visualized by video-enhanced differential interference contrast optics and analyzed with the aid of computer-image-processing techniques. Speeds of translocating organelles were determined at eight to 16 translocation points along a path or "track." Each translocation speed was plotted against its corresponding position on the track to develop a "speed/position diagram." Regardless of mean organelle speed or direction of motion, organelles sharing a common track exhibited similar patterns of "speeding up" and "slowing down" relative to position along the track. Speed position data for organelles translocating the local axonal region of a common track showed no unique patterns (not different from a uniform distribution, p less than 0.05). The unique speed/position patterns exhibited by common tracks were not necessarily related to the patterns of other tracks in the immediate vicinity (distance between tracks of less than 0.50 micron). These findings suggest that there are "common tracks" shared by organelles moving retrogradely and anterogradely; both the organelles and the "track" associated with its translocation play a role in the resultant motion of that organelle; the influence exerted by a common track on the motion of an organelle results in a pattern of speed changes related to position along the track.

Afferent Pathways↗