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The scripting of activities of daily living in normal aging: anticipation and shifting deficits with preservation of sequencing.

The purpose of this study was to elaborate upon Shallice's frontal lobe model by evaluating 20 elderly normal and 20 young adult controls, all women, with cognitive tests, a paper-pencil script generation task and a kitchenette meal preparation task. The elderly were significantly weaker on standardized tests of executive functions and on the paper-pencil script generation task. An anticipation and a sequencing impairment clearly emerged. Though anticipation and shifting were compromised in the kitchenette script task, sequencing was however preserved. This supports Shallice's notion according to which scripting is hierarchically organized with top level components being more frontal lobe dependent (supervisory attentional system or SAS) and the lower level components more tributary to subcortical circuits involving procedural learning (contention scheduling or CS).

Activities of Daily Living↗

PubMed2006

Set shifting deficits in melancholic vs. non-melancholic depression: preliminary findings.

Twenty-two patients with major depressive disorder, 11 of them with melancholic features, and 11 controls were investigated with CANTAB subtests focusing in visual memory/learning and executive functions. Melancholic patients performed worse than the other groups in all tasks and manifested a significant impairment in set shifting. The results are discussed in association with prefrontal dysfunction.

Cognition Disorders↗

PubMed2005

Involuntary orientation of attention to unattended deviant nociceptive stimuli is modulated by concomitant visual task difficulty. Evidence from laser evoked potentials.

OBJECTIVE: Recent laser evoked potential (LEP) studies showed that unattended rare intensity-deviant nociceptive stimuli enhance the LEP vertex positivity P2 ('P400 effect'). It was hypothesized to reflect an involuntary switch of attention to nociceptive events. If true the P400 effect (1) should be produced when attention is focused on a task in another sensory modality (primary task), and (2) should be modulated by the primary task difficulty. METHODS: Subjects had to count the number of visual symbols presented on a screen. In a difficult condition, symbols were digits 1-4 (interference between amount and meaning). In an easy condition, symbols were letters X (no interference). Nociceptive CO2 laser stimuli were simultaneously delivered on the left hand. Occasional stronger deviant stimuli (16%) were presented at random. In additional sessions, the strong stimuli were presented alone in homogenous series (100%). RESULTS: LEP amplitude at about 400 ms was larger for rare deviant than for homogenous stimuli. Visual task difficulty decreased LEP amplitude at this latency. Deviant stimuli seemed also to interfere with performance in the visual task. CONCLUSIONS: The results give evidence for considering the P400 effect as reflecting an involuntary attentional shift to nociceptive events. SIGNIFICANCE: The study provides electrophysiological evidences for an intrusive capacity of pain to attract attention and to decrease behavioural performance in concurrent processes. In turn, such an attentional shift is tampered if attention is very engaged in a concomitant task.

Adult↗

PubMed2006

The contribution of TWIK-related acid-sensitive K+-containing channels to the function of dorsal lateral geniculate thalamocortical relay neurons.

A genetic knockout was used to determine the specific contribution of TWIK-related acid-sensitive K+ (TASK)-1 channels to the function of dorsal lateral geniculate nucleus (DLG) thalamocortical relay (TC) neurons. Disruption of TASK-1 function produced an approximately 19% decrease in amplitude of the standing outward current (ISO) and a 3 +/- 1-mV depolarizing shift in resting membrane potential (Vrest) of DLG neurons. We estimated that current through TASK-1 homodimers or TASK-1/TASK-3 heterodimers contribute(s) approximately one third of the current sensitive to TASK channel modulators in DLG TC neurons. The effects of the TASK channel blocker bupivacaine (20 microM), of muscarine (50 microM), and of H+ on ISO were reduced to approximately 60%, 59%, and shifted to more acidic pH values, respectively. The blocking effect of anandamide on ISO [30 microM; 23 +/- 3% current decrease in wild type (WT)] was absent in TASK-1 knockout (TASK-1-/-) mice (9 +/- 6% current increase). Comparable results were obtained with the more stable anand-amide derivative methanandamide (20 microM; 20 +/- 2% decrease in WT; 4 +/- 6% increase in TASK-1-/-). Current-clamp recordings revealed a muscarine-induced shift in TC neuron activity from burst to tonic firing in both mouse genotypes. Electrocorticograms and sleep/wake times were unchanged in TASK-1-/- mice. In conclusion, our findings demonstrate a significant contribution of TASK-1 channels to ISO in DLG TC neurons, although the genetic knockout of TASK-1 did not produce severe deficits in the thalamocortical system.

Anesthetics, Local↗

PubMed1998

Saccadic and attentional abnormalities in patients with schizophrenia.

BACKGROUND: Abnormal performance on the antisaccade task suggests that patients with schizophrenia have difficulty with the inhibition of reflexive attentional shifts. The aim of the study was to investigate whether deficits in the inhibition of reflexive attentional shifts were specific to the oculomotor modality or whether they could also occur when attentional shifts were made without eye movements (e.g. covert attentional shifts). METHODS: Fifteen medicated patients with chronic schizophrenia and 15 matched controls performed the antisaccade task and the covert orientating task (COVAT) where the probability of targets appearing at the same location of a peripheral cue was varied so that voluntary and reflexive orientating systems had the same goal (80% probability of target and cued condition) or opposite goals (20% probability of target at cued location). A condition where only reflexive orientating was initiated was also included (50% probability of target at cued location). For each of these conditions the stimulus onset asynchrony (SOA) varied between 150 and 350 ms. RESULTS: Patients with schizophrenia showed normal latency and accuracy for visually guided saccades but increased error rates and latency on the antisaccade task. For the COVAT, patients with schizophrenia were unable to use voluntary orientating strategies to inhibit reflexive shifts of covert attention. On conditions where only reflexive orientating was required or when the goals of the reflexive and voluntary orientating systems were the same, patients with schizophrenia showed normal performance. CONCLUSIONS: These results suggest the reflexive orientating mode is normal in patients with chronic schizophrenia. However, these patients have a reduced ability to utilize the voluntary orientating mode to control or inhibit reflexive orientating. This impairment of voluntary control is evident for both overt and covert attentional shifts.

Adult↗

PubMed2006

Conditional responding is impaired in chronic alcoholics.

Bechara (2003) describes a model for disturbances in executive functions related to addiction. This model involves deficits in decision-making and in suppressing pre-potent representations or response patterns. We tested this model in 29 individuals with long-term heavy alcohol dependency and compared their performance with that of 20 control subjects. Only individuals without memory impairment, with normal intelligence and normal visual response times were included. We examined word fluency, object alternation, spatial stimulus-response incompatibility, extra-dimensional shift learning and decision-making using the Gambling task. We subtracted the performance in a control condition from that of the executive condition, in order to focus specifically on the executive component of each task. Only the object alternation and incompatibility tasks revealed significant differences between the group of alcoholics and the control group. Moreover, response times in the object alternation task correlated with duration of alcohol dependency. The results do not argue in favor of a specific deficit in decision-making or in shifting between relevant representations. We conclude that long-term alcohol abuse leads to an impairment in conditional responding, provided the response depends on former reactions or the inhibition of pre-potent response patterns.

Adult↗

PubMed2005

Apolipoprotein E and category fluency: evidence for reduced semantic access in healthy normal controls at risk for developing Alzheimer's disease.

Two groups of non-demented individuals, who differed on genetic risk for Alzheimer's disease (AD) based on their apolipoprotein E (APOE) genotype, were tested on a category fluency task. Twenty varepsilon4 carriers and twenty varepsilon4 non-carriers were tape recorded while saying animal names for ten minutes. Five measures were examined: total names generated; total clusters; mean cluster size; mean within-cluster retrieval time; and mean between-cluster retrieval time. Groups were matched on age and education and scored as normal on a battery of psychometric tests. The varepsilon4 carriers generated significantly fewer names and clusters, and took significantly longer to access clusters, when compared to the varepsilon4 non-carriers. No group differences were found for cluster size or within-cluster retrieval times. We previously reported [Rosen, V. M., Bergeson, J. L., Putnam, K., Harwell, A., Sunderland, T. (2002). Working memory and apolipoprotein E: What's the connection? Neuropsychologia 40, 2226-2233] that the varepsilon4 carriers in the present study scored significantly lower than the varepsilon4 non-carriers on a measure of working memory/attentional capacity [Operation Span Task, see Turner, M. L., Engle, R. W. (1989). Is working memory capacity task dependent? Journal of Memory and Language 28, 127-154]. In the present study, a significant negative relationship found between span performance and between-cluster retrieval times suggested that reduced attentional capacity may have negatively impacted semantic access for the varepsilon4 carriers. Finally, we found significant relationships between a Trail Making Test [Reitan, R. M. (1992). Trail Making Test, manual for administration and scoring. Tucson, AZ: Reitan Neuropsychology Laboratory] "switch" measure (Form B-Form A) and three of the five fluency measures. The findings suggested that the varepsilon4 carrier's reduced attentional capacity may have interfered with their covertly shifting attention among subcategories in the fluency task, resulting in fewer names and clusters generated and longer times to access clusters.

Aged↗

PubMed1998

Cortical fMRI activation produced by attentive tracking of moving targets.

Attention can be used to keep track of moving items, particularly when there are multiple targets of interest that cannot all be followed with eye movements. Functional magnetic resonance imaging (fMRI) was used to investigate cortical regions involved in attentive tracking. Cortical flattening techniques facilitated within-subject comparisons of activation produced by attentive tracking, visual motion, discrete attention shifts, and eye movements. In the main task, subjects viewed a display of nine green "bouncing balls" and used attention to mentally track a subset of them while fixating. At the start of each attentive-tracking condition, several target balls (e.g., 3/9) turned red for 2 s and then reverted to green. Subjects then used attention to keep track of the previously indicated targets, which were otherwise indistinguishable from the nontargets. Attentive-tracking conditions alternated with passive viewing of the same display when no targets had been indicated. Subjects were pretested with an eye-movement monitor to ensure they could perform the task accurately while fixating. For seven subjects, functional activation was superimposed on each individual's cortically unfolded surface. Comparisons between attentive tracking and passive viewing revealed bilateral activation in parietal cortex (intraparietal sulcus, postcentral sulcus, superior parietal lobule, and precuneus), frontal cortex (frontal eye fields and precentral sulcus), and the MT complex (including motion-selective areas MT and MST). Attentional enhancement was absent in early visual areas and weak in the MT complex. However, in parietal and frontal areas, the signal change produced by the moving stimuli was more than doubled when items were tracked attentively. Comparisons between attentive tracking and attention shifting revealed essentially identical activation patterns that differed only in the magnitude of activation. This suggests that parietal cortex is involved not only in discrete shifts of attention between objects at different spatial locations but also in continuous "attentional pursuit" of moving objects. Attentive-tracking activation patterns were also similar, though not identical, to those produced by eye movements. Taken together, these results suggest that attentive tracking is mediated by a network of areas that includes parietal and frontal regions responsible for attention shifts and eye movements and the MT complex, thought to be responsible for motion perception. These results are consistent with theoretical models of attentive tracking as an attentional process that assigns spatial tags to targets and registers changes in their position, generating a high-level percept of apparent motion.

Adult↗

PubMed2003

Deficits of working memory during mental calculation in patients with Parkinson's disease.

Using the dual task paradigm, previous studies have suggested that working memory (WM) deficit is due to depleted attention resources in patients with Parkinson's disease (PD). The aim of this study is to establish whether the WM problems in PD are due to reduced attentional set-shifting resources rather than depletion of attention resources. The task design attempts to eliminate confounding of the deficits in dealing with novel material, a problem documented in PD, by concentrating on WM tasks of mental calculation that are familiar to subjects in daily living. We also administered attention tasks, the Trail Making Test (TMT) that relies primarily on attentional set-shifting and the Kana (Japanese syllabogram) Pick-out Test instead primarily depending on depleted attention resources for allocation. A total of 24 patients with PD and 24 normal controls participated in this study. The PD group showed deficits in mental calculation span and in attentional set-shifting in the TMT-b.Considering the common deficits in alternating processing of mental calculation and TMT-b in PD, the results suggested that the central executive dysfunction in PD during mental calculations was due to reduced attentional set-shifting resources for rapidly alternating operations, rather than the depletion of attentional resources.

Adult↗

PubMed2006

Spatiotemporal analysis of feedback processing during a card sorting task using spatially filtered MEG.

A card sorting paradigm was used to observe the neural correlates of feedback processing in adult participants. Visually presented feedback was used to indicate response accuracy and the requirement to shift response set in a 2-category card sorting task. Magnetoencephalography (MEG) responses to feedback cues were analysed using a beamformer-based spatial filtering algorithm (event-related Synthetic Aperture Magnetometry, erSAM). Analysis of source power revealed activity in rostral anterior cingulate cortex (ACC) only to negative feedback processing, which peaked at 260 ms after stimulus onset. The results are in agreement with both evidence from fMRI on spatial characteristics of negative feedback processing, and evidence from event-related potentials (ERPs) on the temporal profile of this ACC response. The superior temporal gyrus was activated only with positive feedback, reflecting integration of actions with successful outcomes. The present MEG erSAM findings are the first to provide both accurate spatial localization as well as temporal specificity for the neural correlates of feedback processing.

Adult↗

PubMed2004

Influence of object spatial location and task complexity on children's use of their preferred hand depending on their handedness consistency.

The goal of the present study was to compare the use of the preferred versus the nonpreferred hand in children performing two tasks of different levels of complexity, in various positions in space. Right-handed and left-handed consistent children were compared to their inconsistent counterparts. The results showed that the general tendency to use one's preferred hand to grasp an object is more or less pronounced depending on the object's spatial location and the task's complexity. The children used their preferred hand more often even when the object was presented contralaterally, and did so to a greater extent during the more complex task. Inconsistent-handers were more likely to shift to using their nonpreferred hand when the object was presented to this hand's side. Finally, we found that the influence of handedness consistency on hand use for the spatial positions varied with the complexity of the task. These results favor a view of handedness as a dynamic process in which motor preferences interact with task demand, probably through task-related attention.

Child↗

PubMed1996

A network simulation model of large herringbone and parallel milking parlors.

A network simulation model of herringbone and parallel milking parlors was built. Parlor performance was predicted based on the number of cows milked per hour and the amount of milk harvested per shift. Modeled parlors operated using a task-oriented milking routine. The simulation also modeled milking personnel, milking system vacuum pressure and pulsation ratio, and milk yield per cow per milking. The probability distributions of the model components that were used for validation were fitted from data collected from four dairies with the following parlors: double-16 herringbone, double-20 herringbone, double-35 parallel, and double-40 parallel. All fitted distributions were continuous, non-negative, and skewed to the right. The mean number of cows milked per hour (simulated and observed, respectively) was 1) double-16 herringbone, 164.8 and 164.6;2) double-20 herringbone, 207.6 and 206.6; 3) double-35 parallel, 319.2 and 320.2; and 4) double-40 parallel, 361.6 and 362.5. Mean milk yields harvested per shift were 1) double-16 herringbone, 9020 and 9030 kg; 2) double-20 herringbone, 14,800 and 14,746 kg; 3) double-35 parallel, 20,900 and 20,945 kg; and 4) double-40 parallel, 27,100 and 26,974 kg, for simulated and observed yields, respectively. Differences between simulated and observed means for either variable were not significant.

Animals↗

PubMed1995

Deputed power of medical control: the hidden message in the ritual of oral shift reports.

The exchange of oral shift reports between nurses is a prominent part of the everyday routine in a hospital ward. Increased awareness of the more or less explicit functions of such communication is likely to have a positive impact on the nursing profession. Oral shift reports in a nursing care system based on task allocation were therefore observed and analysed. Using an ethnographic approach, reports were tape-recorded, and nurses were interviewed regarding their experiences. During the shift report session, the nurses were found to receive ritually mediated deputed power of medical control from their colleague, but little attention was paid to nursing needs and measures. The nurses clearly demonstrated that they were caught in a system dominated by a medical paradigm that effectively obstructed the progress of nursing as a professional discipline in its own right.

Ceremonial Behavior↗

PubMed2001

Functional anatomical correlates of controlled and automatic processing.

Behavioral studies have shown that consistent practice of a cognitive task can increase the speed of performance and reduce variability of responses and error rate, reflecting a shift from controlled to automatic processing. This study examines how the shift from controlled to automatic processing changes brain activity. A verbal Sternberg task was used with continuously changing targets (novel task, NT) and with constant, practiced targets (practiced task, PT). NT and PT were presented in a blocked design and contrasted to a choice reaction time (RT) control task (CT) to isolate working memory (WM)-related activity. The three-dimensional (3-D) PRESTO functional magnetic resonance imaging (fMRI) sequence was used to measure hemodynamic responses. Behavioral data revealed that task processing became automated after practice, as responses were faster, less variable, and more accurate. This was accompanied specifically by a decrease in activation in regions related to WM (bilateral but predominantly left dorsolateral prefrontal cortex (DLPFC), right superior frontal cortex (SFC), and right frontopolar area) and the supplementary motor area. Results showed no evidence for a shift of foci of activity within or across regions of the brain. The findings have theoretical implications for understanding the functional anatomical substrates of automatic and controlled processing, indicating that these types of information processing have the same functional anatomical substrate, but differ in efficiency. In addition, there are practical implications for interpreting activity as a measure for task performance, such as in patient studies. Whereas reduced activity can reflect poor performance if a task is not sensitive to practice effects, it can reflect good performance if a task is sensitive to practice effects.

Adult↗

PubMed1989

[Occupational medicine and occupational science evaluation of shift work systems with integrated 12-hour shifts].

A field study was performed on 32 male deep drilling workers engaged in hard physical work and 10 male operators with mainly supervisory tasks; both groups working in a shiftwork system including 12 hr shifts. Both the analysis and evaluation of stresses and strains were carried out by means of physiological, psychological and sociological methods. The obtained results show that under the conditions of the given working requirements, existing reproduction conditions, and observed social structure of the populations operating and supervisory activities in a 8 hr shiftwork system including 12 hr shifts are acceptable. In case of hard physical work this shiftwork arrangement can't be agreed to for industrial-medical reasons.

Adult↗

PubMed2002

Contributions of the prefrontal cortex and basal ganglia to set shifting.

Impairments of set shifting have been associated with damage to both the prefrontal cortex (PFC) and to the basal ganglia. The purpose of these experiments was to determine whether damage to the PFC was associated with shifting impairments per se or whether any switching deficits could be attributed to a reduction of working memory capacity. In contrast, shifting impairments were expected for Parkinson patients regardless of memory load, given that these patients seem to have no cognitive deficits other than when having to shift set. To vary working memory demands, a cue to the relevant dimension (letter or shape) in an odd-man-out task was presented or withheld. Pathology to prefrontal areas associated with normal aging was not linked to shifting deficits when working memory load was reduced in a comparison of older and younger adults (Experiment 1). In contrast, set-shifting abilities were still impaired for stroke patients with prefrontal damage regardless of working memory demands (Experiment 2). Parkinson patients were relatively unimpaired on this task (Experiment 2), but began to display shifting deficits when response competition was present in the display (Experiment 3).

Adult↗

PubMed1990

Sparing of attentional relative to mnemonic function in a subgroup of patients with dementia of the Alzheimer type.

Patients with dementia of the Alzheimer type (DAT) received two tests of visual selective attention, together with tests of spatial and visual recognition memory and visuospatial conditional learning previously used to show deficits early in the course of DAT. One set of attentional tests compared visual discrimination learning along intra- and extra-dimensional shifts, using a "total change" design. In the 12 DAT patients capable of attempting the extra-dimensional shift (subgroup 1), performance was equivalent to that of controls. This subgroup was also unimpaired at simple and compound discrimination learning and reversal and an intra-dimensional shift. They were as accurate as controls on a visual search task requiring matching of stimuli on two dimensions with variable numbers of alternatives, but were significantly impaired in the tests of recognition memory and learning. By contrast, the other 13 patients showed marked impairments in the attentional tasks. This subgroup was also significantly worse than subgroup 1 in performance on the visual recognition and conditional learning tasks, and showed greater severity on most of the clinical ratings of dementia. The sparing of attentional shifting in patients early in the course of DAT is contrasted with the impairments previously described in patients with Parkinson's disease with only mild or absent memory loss. The implications of this double dissociation of deficits for understanding the neural bases of the cognitive deficits in these two neurodegenerative diseases are discussed and their significance for the staging of DAT is considered.

Aged↗

PubMed2001

Visuoperceptual impairment in MS patients: nature and possible neural origins.

Failures on visuoperceptual neuropsychological tasks (on neuropsychological tests of visuo-spatial perception or on tests concerning semantic properties of visual objects), may indicate focal deficits of visuoperceptual function, or could be the result of (an)other (peripheral) visual deficit(s), or be the effect of a more general cognitive decline. In multiple sclerosis (MS) patients exhibiting sufficient visual acuity and not showing severe cognitive deterioration, impairment on a comprehensive set of 31 visuoperceptual neuropsychological tasks was compared with spatial resolution deficits (SRD), temporal resolution deficits (TRD) for visual stimuli, abnormal pattern shift visual evoked potential (PSVEP) responses, and failing scores on neuropsychological tasks other than visuoperceptual tasks. Impairment on the visuoperceptual neuropsychological tasks was highly independent from the other abnormal visual and cognitive neurological impairments examined, suggesting that it mostly represented focal deficits. Only TRD in both eyes related to this impairment and this relationship was rather weak. Thus in some MS patients a slowed visual information processing may be one of the combined deficits underlying visuoperceptual neuropsychological task impairment. Given that SRD and TRD were not related to another stage of MS and reflect disturbances of a P (parvocellular channel and ventral stream projections) and M (magnocellular channel and dorsal stream projections) visual-system function respectively, demyelination of a certain M pathway may become a co-determinant of visuoperceptual neuropsychological task impairment more rapidly than damage to a certain P pathway.

Adult↗