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Does the attentional state determine processing dominance in to-be-ignored compound stimuli?

Previous studies (Paquet, 1992, 1994; Paquet and Merikle, 1988) have shown that identification of the local aspect of an attended compound stimulus is delayed by the presence of global distractors within a to-be-ignored compound stimulus, whereas identification of the global aspect is unaffected by local distractors. This asymmetrical pattern of interference indicates that processing of to-be-ignored compound stimuli is characterized by global dominance. In this study, I investigated the hypothesis that these findings were the outcome of subjects adopting an attentional state which favoured processing of global information. Following a procedure developed by Ward (1982), subjects were asked to perform two consecutive identification judgments of the global or the local aspects of two successive relevant compound stimuli, each presented with a to-be-ignored compound stimulus. The first and second judgments were performed either at the same level (i.e., both global or both local), or required switching attention across levels (i.e., global on the first judgment and local on the second, or local on the first judgment and global on the second). The results confirmed that the attentional state (switched vs. unswitched) influences global/local processing speed on the second judgment (Ward, 1982). However, no evidence for local dominance was found when the attentional state favored processing of local information. Instead, global distractors always affected local target identification, whereas interference effects of local distractors upon global target identification were restricted to the attention switching conditions. These findings suggest that the pattern of dominance in to-be-ignored stimuli is not determined by the attentional state, but may be related to fundamental differences in the strength of global and local information channels.

Attention↗

'Where' and 'what' in visual search.

A line segment target can be detected among distractors of a different orientation by a fast 'preattentive' process. One view is that this depends on detection of a 'feature gradient', which enables subjects to locate where the target is without necessarily identifying what it is. An alternative view is that a target can be identified as distinctive in a particular 'feature map' without subjects knowing where it is in that map. Experiments are reported in which briefly exposed arrays of line segments were followed by a pattern mask, and the threshold stimulus-mask interval determined for three tasks: 'what'--subjects reported whether the target was vertical or horizontal among oblique distractors; 'coarse where'--subjects reported whether the target was in the upper or lower half of the array; 'fine where'--subjects reported whether or not the target was in a set of four particular array positions. The threshold interval was significantly lower for the 'coarse where' than for the 'what' task, indicating that, even though localization in this task depends on the target's orientation difference, this localization is possible without absolute identification of target orientation. However, for the 'fine where' task, intervals as long as or longer than those for the 'what' task were required. It appears either that different localization processes work at different levels of resolution, or that a single localization process, independent of identification, can increase its resolution at the expense of processing speed. These possibilities are discussed in terms of distinct neural representations of the visual field and fixed or variable localization processes acting upon them.

Attention↗

Information processing characteristics in subtypes of multiple sclerosis.

The purpose of this study was to evaluate information processing characteristics in patients with multiple sclerosis (MS). We selected 53 patients with MS and 58 matched healthy controls. Using computerized tests, we investigated focused, divided, sustained attention, and executive function, and attempted to pinpoint deficits in attentional control to peripheral or central processing stages. The results substantiate the hypothesis that the slowing of attention-demanding (controlled) information processing underlying more complex cognitive skills is general, i.e. irrespective of type of controlled processing, with MS patients being 40% slower than controls. MS patients may suffer from focused, and divided and sustained attention deficits, as well as from compromised central processing stages, with secondary progressive (SP) patients showing the most extensive range of deficits, closely followed by primary progressive (PP) patients, while relapsing-remitting (RR) patients appear to be much less affected. General slowing appears to be highest in PP and SP type MS patients (50% slower) versus relapsing-remitting MS (24% slower). In contrast to most previous results, (complex) processing speed appeared to be robustly correlated with severity of MS as measured by the expanded disability status scale and with disease duration. Patients did much less differ in accuracy of processing from controls, suggesting the importance of using time strategies in planning everyday life and job activities to compensate for or alleviate MS-related speed handicaps.

Activities of Daily Living↗

Cognitive disturbances in progressive supranuclear palsy.

The cognitive disturbances in progressive supranuclear palsy (PSP) gave rise to the term "subcortical dementia." PSP patients demonstrate prominent recall deficits and moderate forgetfulness although their short-term and implicit perceptual memory processes are intact. PSP patients have both slowed motor responses and dramatically slowed information processing speed. Executive dysfunction appears early in the course of the disease and is relatively severe. The combination of severely slowed information processing and marked executive dysfunction are characteristic of PSP and differentiates it from other dementias. In their landmark description of progressive supranuclear palsy (PSP) as a clinicopathological entity, Steele et al. (1964) reported that cognitive disturbances were present in seven out of their nine patients. Ten years later, Albert et al. (1974) characterized these changes to be part of a "subcortical dementia," They analyzed 5 of their own PSP cases and also reviewed the published literature; they found a common cluster of symptoms, including the presence of forgetfulness, slowness of thought process, emotional or personality changes, and impaired ability to manipulate acquired knowledge. Albert et al. analysis was qualitative, but in the authors' view, clearly differentiated PSP patients from patients with "cortical dementia" who presented with aphasia, apraxia, and/or agnosia. They also suggested that the symptoms found in PSP were similar to those that had previously been described in patients with frontal lobe lesions.

Cognition Disorders↗

Assessment of cognitive recovery following sports related head trauma in boxers.

OBJECTIVE: To prospectively examine recovery of cognitive function within one month following subconcussive sports related head trauma. DESIGN: A prospective study of New York State licensed professional boxers who underwent testing of cognitive functioning before and after (within days, one week, and one month) a professional bout. SETTING: Male professional athletes recruited from the New York State Athletic Commission and local boxing gyms. PARTICIPANTS: Twenty-six licensed professional boxers were enrolled in the protocol. Data is presented on the 18 participants who completed testing on at least three of the four time points. INTERVENTIONS: Serial neuropsychological assessment before and after the athletes engaged in competition. MAIN OUTCOME MEASURES: Neuropsychological measures of cognitive functioning, including new learning and memory, information processing speed, and mental flexibility. RESULTS: A series of repeated measures MANOVAS revealed significant within subject differences across testing on complex information processing and verbal fluency. Post hoc analyses indicated significant differences between time 1 (baseline) and time 4 (one month post), with scores one month following the bout indicating significantly improved performance. Memory scores did not change significantly across testing; however, prior boxing exposure measured by total number of professional bouts was associated with poorer memory performance. CONCLUSIONS: Cognitive testing one month following participation in a professional boxing bout yielded scores suggestive of recovery to a level above the baseline. We conclude that baseline assessment taken during periods of intense training are likely confounded by other pre-bout conditions (i.e., sparring, rapid weight loss, pre-bout anxiety) and do not represent true baseline abilities. Instability of performance associated with mild head injury may complicate the interpretation of post-injury assessments. Practice effects may also confound the interpretation of serial assessments, leading to underestimation of the effects of sports related head trauma. Poorer cognitive performance was evident during the presumed recovery period in boxers with greater exposure to the sport (>12 professional bouts). This finding is consistent with reports of a cumulative effect of repetitive head trauma and the subsequent development of chronic traumatic brain injury. These data have implications for assessing recovery of function following head injury in players of other contact sports as well as determination of return-to-play following an injury.

Adult↗

When global information and local information collide: a brain potential analysis of the locus of interference effects.

The objective of the current experiment was to perform a psychophysiological investigation of the interference effects of global information on the analysis of local information, and vice versa. Subjects' choice reactions to letters at one level of information in a compound letter stimulus were impaired when letters at the other (irrelevant) level signified the opposite response. In the absence of differences in processing speed, global and local information produced symmetrical interference effects. Interference effects did vary, however, as a function of temporal advantage for the processing of information from either level. The individually faster level (be it global or local) interfered with the slower level but was itself relatively immune to such interference by the slower level. Analysis of event-related brain potentials and of the electromyogram revealed that incongruent irrelevant letters induced perceptual conflict but not response competition, thus pointing to a perceptual locus of processing dominance for the faster processed level of information in the compound stimulus.

Adolescent↗

Memory scanning speed in language-disordered children.

Twelve students from classrooms for children with severe language disorders and 12 age-matched controls were evaluated for short-term memory scanning speed using the Sternberg task. Sets of two, three, and four digits were presented via earphones as memory sets, followed by single-probe digits. Reaction time was measured for a verbal response of "yes" or "no" indicating whether the probe was a member of the initial set. Average per-item scanning speed for the normal children was 66 ms, which was significantly different from the 253-ms average scanning speed of the language-disordered group. Many similarities were noted in the performance of the two groups on the memory scanning task. No differences were found in estimates of encoding and response speed, in percentage of errors or in serial or numerical position effects across groups. Results indicate that children with developmental language disorders may demonstrate reduced processing speed or memory retrieval time, which could contribute to linguistic deficits.

Adolescent↗

Literal and figurative interpretations are computed in equal time.

The time courses for constructing literal and figurative interpretations of simple propositions were measured with the response signal, speed-accuracy tradeoff procedure. No differences were found in comprehension speed for literal and figurative strings in a task that required judging whether a string of words was meaningful. Likewise, no differences were found in processing speed for nonsense and figurative strings in a task that required judging whether a string of words was literally true. Figurative strings were less likely to be judged meaningful than were literal strings and less likely to be rejected as literally true than were nonsense strings. The absence of time-course differences is inconsistent with approaches to figurative processing that contend that a figurative interpretation is computed after an anomalous literal interpretation. The time-course profiles suggest that literal and figurative interpretations are computed in equal time but that the meaning of the latter is less constrained than that of the former.

Cognition↗

The nature and determinants of neuropsychological functioning in late-life depression.

CONTEXT: Cognitive impairment in late-life depression (LLD) is highly prevalent, disabling, poorly understood, and likely related to long-term outcome. OBJECTIVES: To determine the characteristics and determinants of neuropsychological functioning LLD. DESIGN: Cross-sectional study of groups of LLD patients and control subjects. SETTING: Outpatient, university-based depression research clinic. PARTICIPANTS: One hundred patients without dementia 60 years and older who met DSM-IV criteria for current episode of unipolar major depression (nonpsychotic) and 40 nondepressed, age- and education-equated control subjects. MAIN OUTCOME MEASURES: A comprehensive neuropsychological battery. RESULTS: Relative to control subjects, LLD patients performed poorer in all cognitive domains. More than half exhibited significant impairment (performance below the 10th percentile of the control group). Information processing speed and visuospatial and executive abilities were the most broadly and frequently impaired. The neuropsychological impairments were mediated almost entirely by slowed information processing (beta =.45-.80). Education (beta =.32) and ventricular atrophy (beta =.28) made additional modest contributions to variance in measures of language ability. Medical and vascular disease burden, apolipoprotein E genotype, and serum anticholinergicity did not contribute to variance in any cognitive domain. CONCLUSIONS: Late-life depression is characterized by slowed information processing, which affects all realms of cognition. This supports the concept that frontostriatal dysfunction plays a key role in LLD. The putative role of some risk factors was validated (eg, advanced age, low education, depression severity), whereas others were not (eg, medical burden, age at onset of first depressive episode). Further studies of neuropsychological functioning in remitted LLD patients are needed to parse episode-related and persistent factors and to relate them to underlying neural dysfunction.

Age Factors↗

The neuropsychology of post-polio fatigue.

To test the hypothesis that post-polio fatigue and its concomitant cognitive deficits are associated with an impairment of attention and not of higher-level cognitive processes, six carefully screened polio survivors were administered a battery of neuropsychological tests. Only subjects reporting severe fatigue, and not those with mild fatigue, demonstrated clinically significant deficits on all tests of attention, concentration, and information processing speed while showing no impairments of cognitive ability or verbal memory. These findings suggest that an impaired ability to maintain attention and rapidly process complex information appears to be a characteristic in polio survivors reporting severe fatigue, because these deficits were documented even when their subjective rating of fatigue was low. This finding supports the hypothesis that a polio-related impairment of selective attention underlies polio survivors' subjective experience of fatigue and cognitive problems.

Adult↗

How serial is serial processing in vision?

Visual search for an element defined by the conjunction of its colour and orientation has previously been shown to be a serial processing task since reaction times increase linearly with the number of distractor elements used in the display. Evidence is presented that there are parallel processing constituents to this serial search. Processing time depended on the ratio of the number of the two distractor types used, suggesting that only one type was scanned. Which type was scanned also depended on the distractor ratio, indicating that this decision was made after stimulus presentation and was based on a parallel figure-ground separation of the stimulus elements. Furthermore, in accordance with this serial scanning model, there was an increase in processing speed (elements scanned per second) with increase in number of elements to be scanned. This increased efficiency suggests that clumps of elements were processed synchronously. Under the stimulation conditions used, clumps contained six to sixteen elements and each clump was processed in 50-150 ms.

Attention↗

Effects of varying post-KR intervals upon children' motor performance.

An experiment using post-KR interval methodology was designed to investigate the developmental relationship of age and processing speed regarding performance on a ballistic linear slide task. The hypothesis drawn from the developmental literature was that, given a short time for processing information, younger children should perform less efficiently than older children and adults. However, an increase in processing time should result in performances being more similar. Subjects in the experiment were 90 female children equally divided among 7 and 11-yr-olds and adults. Within age, subjects were randomly assigned to one of three post-KR interval groups: 3, 6, and 12 sec. Conclusions support the processing deficits hypotheses of Chi (1976): given enough time to process KR, the children's performance was not significantly different from the performance of adults.

Clinical Trial↗

Processes and problems in the formative evaluation of an interface to the Foundational Model of Anatomy knowledge base.

The Digital Anatomist Foundational Model of Anatomy (FMA) is a large semantic network of more than 100,000 terms that refer to the anatomical entities, which together with 1.6 million structural relationships symbolically represent the physical organization of the human body. Evaluation of such a large knowledge base by domain experts is challenging because of the sheer size of the resource and the need to evaluate not just classes but also relationships. To meet this challenge, the authors have developed a relation-centric query interface, called Emily, that is able to query the entire range of classes and relationships in the FMA, yet is simple to use by a domain expert. Formative evaluation of this interface considered the ability of Emily to formulate queries based on standard anatomy examination questions, as well as the processing speed of the query engine. Results show that Emily is able to express 90% of the examination questions submitted to it and that processing time is generally 1 second or less, but can be much longer for complex queries. These results suggest that Emily will be a very useful tool, not only for evaluating the FMA, but also for querying and evaluating other large semantic networks.

Anatomy↗

What have we learned about laryngeal physiology from high-speed digital videoendoscopy?

PURPOSE OF REVIEW: The purpose of this review is to describe recent developments in high-speed videoendoscopy. The applications of this technique are highlighted and important findings regarding vocal fold physiology and voice pathology are discussed. RECENT FINDINGS: The number of applications for digital high-speed imaging has increased during recent years because of the development of camera image sensor systems with increased image resolution of video and television quality. Other improvements are related to computer processing speed and storage capacity and the development of automatic algorithms for quantification and measurements both in time and room dimensions. This is enhanced by combining high-speed videoendoscopy with laser-based measurement systems, acoustic analyses or other glottographic methods, such as flow glottography or electroglottography. High-speed videoendoscopy is currently used in studies of voice mechanisms of phonation (e.g., the voice source can be examined with a high sampling rate, from 1000 to over 8000 frames per second), and in phonation onset or offset. High-speed imaging is also useful in linguistic studies and in the examination of different artistic singing styles, such as extremely high-pitched singing, throat singing, or different pop and rock styles. High-speed videoendoscopy is also used in the examination of patients with voice disorders, particularly with irregular vocal fold vibrations, ventricular phonation, or the phonation of individuals who have had a laryngectomy. SUMMARY: Findings from studies of normal voice physiology and of voice disorders using high-speed imaging are presented and their relevance is discussed.

Electrokymography↗

The temporal dynamics of visual search: evidence for parallel processing in feature and conjunction searches.

Feature and conjunction searches have been argued to delineate parallel and serial operations in visual processing. The authors evaluated this claim by examining the temporal dynamics of the detection of features and conjunctions. The 1st experiment used a reaction time (RT) task to replicate standard mean RT patterns and to examine the shapes of the RT distributions. The 2nd experiment used the response-signal speed-accuracy trade-off (SAT) procedure to measure discrimination (asymptotic detection accuracy) and detection speed (processing dynamics). Set size affected discrimination in both feature and conjunction searches but affected detection speed only in the latter. Fits of models to the SAT data that included a serial component overpredicted the magnitude of the observed dynamics differences. The authors concluded that both features and conjunctions are detected in parallel. Implications for the role of attention in visual processing are discussed.

Adolescent↗

Polymerase chain reaction/ligase detection reaction/hybridization assays using flow-through microfluidic devices for the detection of low-abundant DNA point mutations.

We have microfabricated a flow-through biochip for the analysis of single base mutations in genomic DNA using two different materials: (1) a polycarbonate (PC) chip for performing a primary polymerase chain reaction (PCR) followed by an allele-specific ligation detection reaction (LDR) and (2) a poly(methyl methacrylate) (PMMA) chip for the detection of the LDR products using a universal array platform. The operation of the device was demonstrated by detecting low-abundant DNA mutations in gene fragments (K-ras) that carry point mutations with high diagnostic value for colorectal cancers. The PC microchip was used for sequential PCR/LDR in a continuous-flow format, in which the following three steps were carried out: (1) exponential amplification of gene fragments from genomic DNA; (2) mixing of the resultant PCR product with a LDR mixture via a Y-shaped passive micromixer and (3) ligation of two primers only when the particular mutation was present in the genomic DNA. A PMMA chip was employed as the microarray device, where zip code sequences (24-mer), which were complementary to sequences present on the discriminating primer, were micro-printed into fluidic channels embossed into the PMMA substrate. We successfully demonstrate the ability to detect one mutant DNA in 80 normal sequences with the integrated microfluidic device. The PCR/LDR/hybridization assay using the microchips performed the entire assay at a relatively fast processing speed: 18.7 min for PCR, 8.1 min for LDR, 5 min for hybridization, 10 min for washing and 2.6 min for fluorescence scanning (total processing time=ca. 50 min) with an order of magnitude reduction in reagents compared to bench-top formats.

Animals↗

Adolescent substance use disorders and comorbidity.

It is imperative to know what risk factors are more likely to appear during specific developmental stages so that identification and interventions can be used to decrease the risk for future SUD. Continued surveying of risk factors that can occur at any stage in childhood are important to ensure that other risk factors are anticipated and intervened upon as well. Multiple risk factors increase the magnitude of the risk for SUD, and therefore all risk factors should be detected to convert these to protective factors. Screening instruments that can assess risk factors found to increase the risk for substance abuse can be found in examples, such as the Drug Usage Screening Instrument [81] and the Problem-Oriented Screening Instrument for Teenagers. The detection of risk factors by primary care providers is becoming increasingly important. However, other professionals are beginning to recognize that early recognition and treatment can enable a youth to go on to a productive life in other arenas as well. Drug courts and diversion programs are beginning to treat first-time offenders and their families rather than taking the punitive approach. These have proven to be very successful. Primary care physicians also should become familiar with motivational enhancement therapy when confronting a youth with a suspected substance abuse problem [57]. This method has proven to be more effective in getting youth into treatment than the direct, confrontational style, which often puts the youth in a defensive mode. Motivational enhancement therapy includes interventions that are delivered in a neutral and empathetic way. The six components of motivational enhancement therapy (also called FRAMES) include: Feedback on personal impairment Emphasis on personal responsibility Clear advice to change Menu of alternative options Empathy as a counseling style Self-efficacy In this way, a clinician can elicit pros and cons, give advice, provide choices, practice empathy, clarify goals, and remove barriers. This technique allows youth to be less defensive and more proactive. Monti et al. [59] have demonstrated that this technique has been useful in getting youth into treatment. Primary care physicians can use instruments that will assess the possibility of both externalizing (e.g., ADHD) and internalizing (e.g., depression and anxiety) disorders. Examples of this type of instrument are the Auchenbach child behavior checklist, teacher report form, and youth self-report form, which survey symptoms for these disorders [1]. Social anxiety disorder can be detected by asking whether the prelatency child went into new situations willingly and tended to hang back or whether the child had difficulty separating from his or her parents. Other questions to ask are whether the child tended to isolate or was fearful of speaking in front of the class. Of course, any bruising or behavior that suggests exposure to adult-related sexual acts may cause concern for physical or sexual abuse and possible PTSD. However, interest in sex earlier than expected for the age of the child may also indicate the possibility of bipolar disorder. These children have many symptoms of ADHD with a high degree of irritability and may seem boastful or grandiose. They may be "daredevils" with no fear of dangerous consequences. Referral to a specialist is necessary to evaluate these children further. Because substance use at age 14 or 15 years can be predicted by academic and social behavior at ages 7 to 9 years, early detection of poor social skills and learning difficulties is essential [43]. Learning disorders can be uncovered by asking the school to do an evaluation. However, schools having economic problems may not be able to accommodate all requests. A parent may have to pay a private provider to complete this workup because insurance companies seldom pay for educational testing. Learning disorders may go undetected because many school systems opt to use a higher deviation from the full-scale IQ to detect learning problems. For instance, if a student has an IQ of 115, the standard nationally recommended deviation from this IQ to detect a learning disorder is 15. Therefore, any child who scores 100 or less on an achievement test should be considered to have a learning disorder. Some schools prefer to use a deviation of up to 23 so that learning disorders are not detected. Few schools screen for processing problems, including auditory and visual motor processing problems, processing speed, comprehension, and short-term and long-term memory problems. This is extremely important because ADHD can be confused with an auditory processing problem. Stimulants may help this condition, but accommodations must be made to ensure continued success. Early-intervention programs, such as Drug Abuse Resistance Education (DARE), proved to be ineffective because the programs did not target components that have been shown to predict future drug use [54]. One program that has targeted these components, normative beliefs, lifestyle-behavior incongruence, and commitment is the All Stars program [39,40]. A strong initial dosage with booster interventions for at least 2 years is also important [10]. Before a child is diagnosed with oppositional defiant disorder or conduct disorder, every effort should be made to detect any underlying psychiatric disorder that has not been treated and therefore may look like a conduct disorder (e.g., bipolar disorder). Proper psychopharmacologic interventions should be made for psychiatric disorders. If one drug has been ineffective, another untreated psychiatric disorder may be present, and it is always important to tease out what remaining symptoms are present after a therapeutic trial has been tried. It is important to form a team approach so that all risk factors can be approached. Members of the team often include a primary care physician, a child psychologist, the parents, the patient, a teacher, a school counselor, a child psychiatrist, and sometimes a pediatric neurologist. No one member of the treatment team can provide all of the necessary services to prevent the future risk for substance abuse.

Adolescent↗

Mechanism of antigen presentation after hypertonic loading of soluble antigens.

Hypertonic loading of proteins into cells has been used to introduce soluble proteins into the major histocompatibility complex class I pathway of antigen presentation followed by cytotoxic T-lymphocyte (CTL) induction. The precise mechanism for this pathway is not completely understood. The antigen is either processed and presented by/on the same cell or by professional antigen-presenting cells (APC) after taking up the antigen from damaged or apoptotic cells. After loading labelled ovalbumin (OVA), it could be co-precipitated with the proteasome complex, supporting the role of this pathway for antigen processing. The processing speed however, appeared to be slow since intact OVA could be detected inside the cells even after 18 hr. This corresponded well with the processing of OVA by isolated proteasomes. On the other hand, enough peptides for recognition of target cells by CTLs were generated in this reaction. One reason for the low level of processing might be that hypertonic loading may damage the cells and inhibit direct processing. In fact, at least 50% of the cells became positive for Annexin V binding after hypertonic loading which indicates severe membrane alterations usually associated with the progress of apoptosis. Annexin V binds to phosphatidylserine residues which also serve as ligand for CD36 expressed on monocytes and some immature dendritic cells. This may direct the phagocytic pathway to hypertonically loaded cells and thus enable professional APCs to present OVA-peptides. Therefore, in addition to the direct processing of OVA, CTLs can be primed by professional APC after uptake of apoptotic, OVA-loaded cells.

Animals↗