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PubMed1990

The anterior cingulate cortex mediates processing selection in the Stroop attentional conflict paradigm.

Regional cerebral blood flow, an index of local neuronal activity, was measured using positron emission tomography (PET) during the performance of the classic Stroop color/word task in eight healthy right-handed subjects. In the first condition of this paradigm, subjects name the color of the words presented on a video monitor. All the words are the color names congruent to the color presented (e.g., the noun "red" displayed in red color). In the second condition, subjects also name the color of the words presented on the monitor. However, during these trials all words are color names incongruent to the color presented (e.g., the noun "red" displayed in green color). The difference in brain activity between these two conditions (i.e., incongruent minus congruent) could reveal brain systems involved in the attentionally mediated resolution of the conflict between the habitual response of reading words vs. the task demands of naming the color of the words--i.e., the Stroop interference effect. The most robust responses occurred in the anterior cingulate cortex. Other responses noted were in the left premotor cortex, left postcentral cortex, left putamen, supplementary motor area, right superior temporal gyrus, and bilateral peristriate cortices. These data provide support for the role of the anterior cingulate cortex in attentional processing through the selection and recruitment of processing centers appropriate for task execution. Furthermore, the extensive distributed network of activated regions suggests that the Stroop interference effect cannot be explained simply in terms of stimulus encoding or response interference.

Adult↗

PubMed2006

Parietal function in good and poor readers.

BACKGROUND: While there are many psychophysical reports of impaired magnocellular pathway function in developmental dyslexia (DD), few have investigated parietal function, the major projection of this pathway, in good and poor readers closely matched for nonverbal intelligence. In view of new feedforward-feedback theories of visual processing, impaired magnocellular function raises the question of whether all visually-driven functions or only those associated with parietal cortex functions are equally impaired and if so, whether parietal performance is more closely related to general ability levels than reading ability. METHODS: Reading accuracy and performance on psychophysical tasks purported to selectively activate parietal cortex such as motion sensitivity, attentional tracking, and spatial localization was compared in 17 children with DD, 16 younger reading-age matched (RA) control children, and 46 good readers of similar chronological-age (CA) divided into CA-HighIQ and a CA-LowIQ matched to DD group nonverbal IQ. RESULTS: In the age-matched groups no significant differences were found between DD and CA controls on any of the tasks relating to parietal function, although performance of the DD group and their nonverbal IQ scores was always lower. As expected, CA and RA group comparisons indicated purported parietal functioning improves with age. No difference in performance was seen on any of the parietally driven tasks between the DD and age-nonverbal IQ matched groups, whereas performance differentiated the DD group from the age-matched, higher nonverbal IQ group on several such tasks. An unexpected statistical difference in performance between lower reading age (DD and RA children) and all higher reading age (CA) children was seen on a test of chromatic sensitivity, whereas when high and low nonverbal IQ normal readers were compared performance was not different CONCLUSION: The results indicate that performance on purported parietal functions improves with age and may be more associated with nonverbal mentation than reading accuracy. Performance on a cognitively demanding task, traditionally considered to rely on ventral stream functions, was more related to reading accuracy.

Journal Article↗

PubMed2006

Intraindividual variability in vigilance performance: does degrading visual stimuli mimic age-related "neural noise"?

Intraindividual performance variability, or inconsistency, has been shown to predict neurological status, physiological functioning, and age differences and declines in cognition. However, potential moderating factors of inconsistency are not well understood. The present investigation examined whether inconsistency in vigilance response latencies varied as a function of time-on-task and task demands by degrading visual stimuli in three separate conditions (10%, 20%, and 30%). Participants were 24 younger women aged 21 to 30 years (M = 24.04, SD = 2.51) and 23 older women aged 61 to 83 years (M = 68.70, SD = 6.38). A measure of within-person inconsistency, the intraindividual standard deviation (ISD), was computed for each individual across reaction time (RT) trials (3 blocks of 45 event trials) for each condition of the vigilance task. Greater inconsistency was observed with increasing stimulus degradation and age, even after controlling for group differences in mean RTs and physical condition. Further, older adults were more inconsistent than younger adults for similar degradation conditions, with ISD scores for younger adults in the 30% condition approximating estimates observed for older adults in the 10% condition. Finally, a measure of perceptual sensitivity shared increasing negative associations with ISDs, with this association further modulated as a function of age but to a lesser degree by degradation condition. Results support current hypotheses suggesting that inconsistency serves as a marker of neurological integrity and are discussed in terms of potential underlying mechanisms.

Adult↗

PubMed2005

A new approach to spatial covariance modeling of functional brain imaging data: ordinal trend analysis.

In neuroimaging studies of human cognitive abilities, brain activation patterns that include regions that are strongly interactive in response to experimental task demands are of particular interest. Among the existing network analyses, partial least squares (PLS; McIntosh, 1999; McIntosh, Bookstein, Haxby, & Grady, 1996) has been highly successful, particularly in identifying group differences in regional functional connectivity, including differences as diverse as those associated with states of awareness and normal aging. However, we address the need for a within-group model that identifies patterns of regional functional connectivity that exhibit sustained activity across graduated changes in task parameters. For example, predictions of sustained connectivity are commonplace in studies of cognition that involve a series of tasks over which task difficulty increases (Baddeley, 2003). We designed ordinal trend analysis (OrT) to identify activation patterns that increase monotonically in their expression as the experimental task parameter increases, while the correlative relationships between brain regions remain constant. Of specific interest are patterns that express positive ordinal trends on a subject-by-subject basis. A unique feature of OrT is that it recovers information about functional connectivity based solely on experimental design variables. In particular, there is no requirement by OrT to provide either a quantitative model of the uncertain relationship between functional brain circuitry and subject variables (e.g., task performance and IQ) or partial information about the regions that are functionally connected. In this letter, we provide a step-by-step recipe of the computations performed in the new OrT analysis, including a description of the inferential statistical methods applied. Second, we describe applications of OrT to an event-related fMRI study of verbal working memory and H(2)15O-PET study of visuo-motor learning. In sum, OrT has potential applications to not only studies of young adults and their cognitive abilities, but also studies of normal aging and neurological and psychiatric disease.

Adult↗

PubMed2000

Spatial stimulus-response compatibility and coding of tactile motor events: influence of distance between stimulated and responding body parts, spatial complexity of the task and sex of subject.

We studied spatial stimulus response compatibility in the somatosensory modality by instructing 16 men and 16 women to press a key using the left or the right thumb in response to a nonnoxious electric stimulation delivered either to the left or to the right little finger or, in different blocks, to the left or to the right malleolar region. The task was performed in compatible (stimulus and key-response on the same side of the corporeal midline) and in incompatible conditions (stimulus and key-response on opposite sides of the corporeal midline). In Exp. 1 subjects were tested while keeping their limbs in anatomic position; in Exp. 2 subjects performed the task while keeping the left upper and lower limbs on the right side and the right limbs on the left side of the bodily midline (crossed position). The compatibility effect was observed in both experiments and was higher for stimuli delivered to the little finger than to the malleolar region. This suggests that the cost of inhibiting compatible responses is maximal when stimulated and responding body parts are contiguous. Moreover, in the spatially most demanding task (Exp. 2) men outperformed women for both speed and accuracy suggesting a sex related specialisation in the spatial processing of somatosensory information.

Adult↗

PubMed1986

Cognitive behavioural strategies and anxiety in elite orienteers.

The primary purpose of this exploratory field study was to examine the use of cognitive behavioural strategies by highly skilled orienteers prior to and during competition. A secondary purpose of the study was to investigate whether differences in the level of qualification in orienteering is related to state anxiety. The subjects were divided into three classes with respect to their international and national records. The first two classes (A and B) were composed of international and national level athletes. The third class (C) included orienteers with unknown international records. Examination of the use of behavioural cognitive strategies during competition indicated that all orienteers reported a moderate use of mental imagery, above moderate use of inner talk and a focus of attention on present action rather than past or future. The other major findings were that prior to competition, superior orienteers reported use of higher self-efficacy, more positive outcome expectations and more task demand orientation than their less successful counterparts. Top orienteers coped more successfully with pre-competition anxiety by lowering their anxiety to a more moderate level prior to the actual performance.

Anxiety↗

PubMed2005

Effects of experimentally-induced anterior knee pain on knee joint position sense in healthy individuals.

PURPOSE: The ability to sense the position of limb segments is a highly specialised proprioceptive function important for control of movement. Abnormal knee proprioception has been found in association with several musculoskeletal pathologies but whether nociceptive stimulation can produce these proprioceptive changes is unclear. This study evaluated the effect of experimentally induced knee pain on knee joint position sense (JPS) in healthy individuals. STUDY DESIGN: Repeated measures, within-subject design. METHODS: Knee JPS was tested in 16 individuals with no history of knee pathology under three experimental conditions: baseline control, a distraction task and knee pain induced by injection of hypertonic saline into the infrapatellar fat pad. Knee JPS was measured using active ipsilateral limb matching responses at 20 degrees and 60 degrees flexion whilst non-weightbearing (NWB) and 20 degrees flexion single leg stance. During the tasks, the subjective perception of distraction and severity of pain were measured using 11-point numerical rating scales. RESULTS: Knee JPS was not altered by acute knee pain in any of the positions tested. The distraction task resulted in poorer concentration, greater JPS absolute errors at 20 degrees NWB, and greater variability in errors during the WB tests. There were no significant correlations between levels of pain and changes in JPS errors. Changes in JPS with pain and distraction were inversely related to baseline knee JPS variable error in all test positions (r=-0.56 to -0.91) but less related to baseline absolute error. CONCLUSION: Knee JPS is reduced by an attention-demanding task but not by experimentally induced pain.

Adult↗

PubMed2005

Longitudinal consistency of the relationship between depression symptoms and cognitive functioning in multiple sclerosis.

BACKGROUND: Lifetime prevalence rates of cognitive dysfunction and depression in multiple sclerosis (MS) have typically been reported to be approximately 50 percent. However, an inconsistent relationship between these two common features of MS has been reported in the literature. Because neurovegetative depression symptoms overlap with MS symptoms, it may be that literature inconsistencies can partly be explained by the fact that only those depression symptom clusters unambiguously reflective of depression are associated with cognitive dysfunction. OBJECTIVE: To explore the relationship between different depression symptom clusters and a battery of tests measuring cognitive domains commonly impaired in MS and was examined at two time points 3 years apart. METHODS: The Chicago Multiscale Depression Inventory was employed to measure mood, negative evaluative, and neurovegetative symptom clusters in 53 MS patients who were also administered a battery of neuropsychological tests. RESULTS: At time point 1, Mood and Evaluative Chicago Multiscale Depression Inventory scales were significantly associated with tasks of complex speeded attention, planning, and working memory. At time point 2, the Evaluative scale was still significantly associated with these domains, in addition to spatial memory; however, all of the significant correlations with the Mood scale dropped out. CONCLUSION: These results show that negative evaluative depression symptoms are most consistently predictive of cognitive dysfunction in MS. It may be that negative evaluative depression symptoms use up available cognitive capacity, thus compromising performance on cognitive capacity demanding tasks in MS patients.

Cognition Disorders↗

PubMed1993

European isolation and confinement study. Mental performance.

Six EMSInauts were confined for 28 days in a hyperbaric chamber complex at a low overpressure. During this period they were repeatedly given four different standard mental performance tests: (1) Operational Test of sustained attention vigilance; (2) short-term memory; (3) visual reaction time; and (4) cognitive evoked brain potentials (N100 and P300). The aim of the study was to determine whether there were any general or specific effects on mental performance during the isolation period. For the simple mental performance tests (operational test and visual reaction time), a distinct learning effect over the 28 days of isolation could be detected. On the more cognitive demanding tasks such as in the short-term memory test, patterns of impairment were found. Of the cognitive evoked brain potentials recorded, the noncognitive N100 wave latency was unchanged throughout the isolation period. The P300 wave latency, related to cognitive functioning, showed lower values in the middle and higher values at the end of the isolation period, compared with the pre-isolation values. Although a few individual, transient impairments of function were noticed in the more demanding tests, it is concluded that the mental performance of the six EMSInauts appeared to remain basically unchanged throughout the isolation phase, both at the group level and the individual level.

Evoked Potentials, Auditory↗

PubMed1992

Brain mapping in dysphonemic dyslexia: in resting and phonemic discrimination conditions.

Topographic mapping of EEG bands and alpha asymmetry were analyzed during resting conditions and an auditory phonemic discrimination task (APD) in carefully screened samples of 9.0- to 12-year-old control and dysphonemic-sequencing dyslexic children. The EEG was recorded over the entire scalp, with a linked ears reference. We found: (1) no differences between groups during resting conditions in any frequency band analyzed; (2) a left hemisphere alpha responsiveness in dyslexic children during the APD condition; and (3) a beta 2 decrease in the left posterior quadrant in dyslexics during the APD condition. We conclude that the lower alpha and beta 2 responsiveness may be due to a diminished cortical reactivity and may be related to intrinsic disorganization of the neural processors associated directly with the APD task demands, the alpha activity reflecting poor attention to an external stimuli source and the beta 2 decrease reflecting an unusual processing associated with the linguistic cognitive requirements.

Auditory Perception↗

PubMed1996

Reaction time and variability 5 and 10 years after traumatic brain injury.

Improvement in performance can occur up to 10 years after traumatic brain injury (TBI). Few previous studies have examined the long-term effects of TBI on information processing. This study used reaction time (RT) tasks of increasing complexity with 10-year post-injury, 5-year post-injury, and control groups to assess any such effects. There were no significant group differences in mean RT; however, in the groups of persons with head injury only, response latency was related to age and to task demands. Older members of the groups of persons with head injury were slower than controls. The variability in performance was significantly higher in the 5-year post-injury group than in both the 10-year group and the control group. There were no significant differences among the groups in their ability to inhibit the processing of redundant information. There were no correlations between any dependent measure and severity of injury. Speed of processing is more sensitive to task complexity in individuals with head injury, but only when age at injury is considered. Most importantly, for rehabilitation purposes, recovery of consistency in performance can be expected more than 5 years after a TBI.

Adolescent↗

PubMed2002

Is pain-related fear a predictor of somatosensory hypervigilance in chronic low back pain patients?

Pain-related fear has been found to be associated with increased disability and increased pain perception in patients with chronic low back pain. A possible mechanism by which pain-related fear could lead to increased pain perception is heightened attention to somatosensory sensations. In the present study, chronic pain patients reporting either a high or low level of pain related fear and control participants performed an auditory reaction time task, while occasionally non-painful electrical stimuli--accompanied by threatening instructions--were given to the arm or back. In the primary task condition, participants had to perform the auditory task while ignoring the electrical stimuli. Next, the task was presented under dual task conditions in which participants had to respond both to tones as well as to detection of electrical stimuli. It was hypothesized that for the primary task, high fearful patients would show greater disruption of performance on the auditory task than low fearful patients and controls when stimuli were presented to the back. For the dual task, slower reaction times for the auditory task, in combination with faster detection of electrical stimuli was expected. The hypotheses were not confirmed but patients scoring high on pain-related fear did show an overall increase in reaction time for all conditions of the primary task, with or without simultaneous stimulation. Regression analyses demonstrated that high pain-related fear was associated with increased reaction time to tones both in patients and healthy controls, and that within patients pain-related fear was a better predictor of reaction time to tones than present pain intensity. The findings may be interpreted as showing that patients with elevated levels of pain-related fear habitually attend to somatic sensations, giving less priority to other attention-demanding tasks.

Adult↗

PubMed2000

Teamwork in multi-person systems: a review and analysis.

As the scope and complexity of modern task demands exceed the capability of individuals to perform, teams are emerging to shoulder the burgeoning requirements. Accordingly, researchers have striven to understand and enhance human performance in team settings. The purpose of this review is to summarize that research, from the theoretical underpinnings that drive it, to the identification of team-level elements of success, to the methodologies and instruments that capture and measure those characteristics. Further specified are three important avenues to creating successful teams: team selection, task design and team training. In other words, one can select the right people, provide them with a task engineered for superior performance and train them in the appropriate skills to accomplish that task. Under task design, new technologies and automation are examined that both support and impede team functioning. Finally, throughout are provided critical remarks about what is known about teamwork and what is needed to be known to move the science and practice of team performance forward. The paper concludes with the identification of team issues that require further investigation.

Efficiency↗

PubMed2000

Linguistic cues and memory for synthetic and natural speech.

Past research has demonstrated that there are cognitive processing costs associated with comprehension of speech generated by text-to-speech synthesizers, relative to comprehension of natural speech. This finding has important performance implications for the many applications that use such systems. The purpose of this study was to ascertain whether certain characteristics of synthetic speech slow on-line, real-time cognitive processing. Whereas past research has focused on the phonemic acoustic structure of synthetic speech, we manipulated prosodic, syntactic, and semantic cues in a task requiring participants to recall sentences spoken either by a human or by one of two speech synthesizers. The findings were interpreted to suggest that inappropriate prosodic modeling in synthetic speech was the major source of a performance differential between natural and synthetic speech. Prosodic cues, along with others, guide the parsing of speech and provide redundancy. When these cues are absent or inaccurate, the additional burden placed on working memory may exceed its capacity, particularly in time-limited, demanding tasks. Actual or potential applications of this research include improvement of text-to-speech output systems in warning systems, feedback devices in aerospace vehicles, educational and training modules, aids for the handicapped, consumer products, and technologies designed to increase the functional independence of older adults.

Adolescent↗

PubMed1999

Feature extraction and quantification of the variability of dynamic performance profiles due to the different sagittal lift characteristics.

Investigation of manual material handling (MMH) tasks, such as lifting, requires the quantification of the various kinematic and kinetic parameters of performance for assessment of the functional capacity and/or task demand profiles. Traditional statistical descriptive analyses usually involve computing the summary statistics (maximum, minimum, mean, and/or range) of the resulting performance parameters over the cycle duration (i.e., lifting/lowering cycle). Consequently, the significant information content of the time-varying signals is diminished, limiting the sensitivity of subsequent hypothesis testing procedures. The present study developed a methodology for representing and quantifying performance data variability of the kinematic and kinetic motion profiles due to the different lift characteristics (load, mode, and speed) during MMH tasks while capturing the temporal characteristics. Using a database of motion profiles from a manual lifting experiment, the Karhunen-Loeve Expansion (KLE) feature extraction technique was shown to be quite effective for representing the various motion profiles. The number of basis vectors (eigenvectors) and corresponding coefficients needed for accurate representation were substantially smaller than the original data set, resulting in data compression. Moreover, the effects of lift characteristics were investigated using analysis of variance techniques that recognize the vectorial constitution of the waveforms. The application of these techniques will enable the quantification of highly phasic profiles and enhance the ability to document the effect of intervening measures such as educational or physical training/exercise on the kinematic and kinetic patterns of performance. Additionally, the differential influence of lift characteristics on the variability of performance during different phases of lifting and lowering provides added resolution in the analysis of MMH tasks.

Adult↗

PubMed2006

Sensitivity of alpha band ERD to individual differences in cognition.

According to the neural efficiency hypothesis, brighter individuals might be characterized by lower and topographically more differentiated brain activation than less intelligent individuals, presumably reflecting a more specialized recruitment of task-related areas. The findings of several studies analyzing the event-related desynchronization (ERD) in the (upper) alpha frequency band have corroborated and elaborated the original neural efficiency hypothesis. In this chapter, we review classical and recent findings and argue in favor of a more differentiated picture of this phenomenon, emphasizing the role of participants' sex, task complexity, and material specificity, as well as the importance to select an adequate external criterion (intelligence measure). Also, recent ERD findings related to emotional intelligence and creativity as well as recent studies focusing on practice, learning ability, and expertise are presented, which point to the need of a broader neurophysiological ability concept. The reviewed findings point at the high suitability of the ERD method to uncover consistent and stable individual differences in people's brain activation patterns when engaged in performing cognitively demanding tasks.

Alpha Rhythm↗

PubMed2003

The rat nucleus accumbens is involved in guiding of instrumental responses by stimuli predicting reward magnitude.

The present study examined the involvement of N-methyl-d-aspartate (NMDA), alpha-amino-3-hydroxy-5-methyl-4-isoxazolpropionate/kainate (AMPA/KA) and dopamine receptors in the nucleus accumbens (ACB) in influencing reaction times of instrumental responses by the expectancy of reward. A simple reaction time task demanding conditioned lever release was used in which the upcoming reward magnitude was signalled in advance by discriminative cues. After training, in control rats with vehicle infusions (0.5 micro L) into the ACB, reaction times of responses were significantly shorter to the discriminative cue predictive of high reward magnitude. Indirect stimulation of dopamine receptors in the ACB by d-amphetamine (20 micro g/0.5 micro L) decreased reaction times, impaired their guidance by cue-associated reward magnitudes and reduced the accuracy of task performance. Blockade of AMPA/KA receptors in the ACB by 6-cyano-7-nitroquino-xaline-2,3-dione (0.75 and 2.5 micro g/0.5 micro L) or NMDA receptors by d(-)-2-amino-5-phosphonopentanoic acid (5 micro g/0.5 micro L) produced a general increase in reaction times, but left guidance of reaction times by cue-associated reward magnitudes unaffected. Thus, stimulation of intra-ACB ionotropic glutamate receptors is critically involved in modulating the speed of instrumental responding to cues predictive for reward magnitude, but is not required for intact performance of previously learned instrumental behaviour.

6-Cyano-7-nitroquinoxaline-2,3-dione↗

PubMed2006

Contribution of the shaping and restraint components of Constraint-Induced Movement therapy to treatment outcome.

Two important components of Constraint-Induced Movement therapy are thought to be intense training of the more-impaired arm and physical restraint of the less-impaired arm. This preliminary study examined the effects of type of training (task-practice, shaping) and restraint (sling, half-glove, no restraint) on treatment outcomes. Seventeen individuals at least 1-year post-stroke with mild/moderate upper extremity motor deficit were consecutively assigned to Sling and Task-practice, Sling and Shaping, Half-glove and Shaping, and Shaping Only groups. Task-practice involved repetitive more-impaired arm training on functional tasks for 6 hr/day for 10 consecutive weekdays. Shaping differed from task-practice in that task demands were progressively increased and immediate performance feedback was provided frequently and systematically. "Sling" groups placed the less-impaired arm in a resting hand-splint/sling assembly for most waking hours over the 2-week intervention, while the "Half-glove" group wore a modified gardening glove as a reminder not to use the more affected arm in the life situation. There were no between-group differences in outcome at post-treatment, although two-years afterwards Sling & Task-practice and Half-glove & Shaping participants showed larger and smaller retention of gains, respectively, than those in the Sling & Shaping group. Thus, long-term outcomes may have been affected by type of more-impaired arm motor training and less-impaired arm restraint. These variables, however, were confounded with between-group differences in training intensity, limiting confidence in this conclusion.

Aged↗