Motor Response Task Research Articles

ERP evidence of attentional somatosensory processing and stimulus-response coupling under different hand and arm postures.

We investigated (1) the effects of divided and focused attention on event-related brain potentials (ERPs) elicited by somatosensory stimulation under different response modes, (2) the effects of hand position (closely-placed vs. separated hands) and arm posture (crossed vs. uncrossed forearms) on the attentional modulation of somatosensory ERPs, and (3) changes in the coupling of stimulus- and response-related processes by somatosensory attention using a single-trial analysis of P300 latency and reaction times. Electrocutaneous stimulation was presented randomly to the thumb or middle finger of the left or right hand at random interstimulus intervals (700-900 ms). Subjects attended unilaterally or bilaterally to stimuli in order to detect target stimuli by a motor response or counting. The effects of unilaterally-focused attention were also tested under different hand and arm positions. The amplitude of N140 in the divided attention condition was intermediate between unilaterally attended and unattended stimuli in the unilaterally-focused attention condition in both the mental counting and motor response tasks. Attended infrequent (target) stimuli elicited greater P300 in the unilaterally attention condition than in the divided attention condition. P300 latency was longer in the divided attention condition than in the unilaterally-focused attention condition in the motor response task, but remained unchanged in the counting task. Closely locating the hands had no impact, whereas crossing the forearms decreased the attentional enhancement in N140 amplitude. In contrast, these two manipulations uniformly decreased P300 amplitude and increased P300 latency. The correlation between single-trial P300 latency and RT was decreased by crossed forearms, but not by divided attention or closely-placed hands. Therefore, the present results indicate that focused and divided attention differently affected middle latency and late processing, and that hand position and arm posture also differently affected attentional processes and stimulus-response coupling.

Across the adult lifespan the ipsilateral sensorimotor cortex negative BOLD response exhibits decreases in magnitude and spatial extent suggesting declining inhibitory control

Ipsilateral sensorimotor (iSM1) cortex negative BOLD responses (NBR) are observed to unilateral tasks and are thought to reflect a functionally relevant component of sensorimotor inhibition. Evidence suggests that sensorimotor inhibitory mechanisms degrade with age, along with aspects of motor ability and dexterity. However, understanding of age-related changes to NBR is restricted by limited comparisons between young vs old adults groups with relatively small samples sizes. Here we analysed a BOLD fMRI dataset (obtained from the CamCAN repository) of 581 healthy subjects, gender-balanced, sampled from the whole adult lifespan performing a motor response task to an audiovisual stimulus. We aimed to investigate how sensorimotor and default-mode NBR characteristics of magnitude, spatial extent and response shape alter at every decade of the aging process. We observed a linear decrease in iSM1 NBR magnitude across the whole lifespan, whereas the contralateral sensorimotor (cSM1) PBR magnitude was unchanged. An age-related decrease in the spatial extent of NBR and an increase in the ipsilateral positive BOLD response (PBR) was observed. This occurred alongside an increasing negative correlation between subject's iSM1 NBR and cSM1 PBR magnitude, reflecting a change in the balance between cortical excitation and inhibition. Conventional GLM analysis, using a canonical haemodynamic response (HR) function, showed disappearance of iSM1 NBR in subjects over 50 years of age. However, a deconvolution analysis showed that the shape of the iSM1 HR altered throughout the lifespan, with significantly delayed time-to-peak and decreased magnitude. The most significant decreases in iSM1 HR magnitude occurred in older age (>60 years) but the first changes in HR shape and timing occurred as early as 30 years, suggesting the possibility of separate mechanisms underlying these alterations. Reanalysis using data-driven HRs for each decade detected significant sensorimotor NBR into late older age, showing the importance of taking changes in HR morphology into account in fMRI aging studies. These results may reflect fMRI measures of the age-related decreases in transcollosal inhibition exerted upon ipsilateral sensorimotor cortex and alterations to the excitatory-inhibitory balance in the sensorimotor network.

Multi-level decoding of task sets in neurophysiological data during cognitive flexibility

SummaryCognitive flexibility is essential to achieve higher level goals. Cognitive theories assume that the activation/deactivation of goals and task rules is central to understand cognitive flexibility. However, how this activation/deactivation dynamic is implemented on a neurophysiological level is unclear. Using EEG-based multivariate pattern analysis (MVPA) methods, we show that activation of relevant information occurs parallel in time at multiple levels in the neurophysiological signal containing aspects of stimulus-related processing, response selection, and motor response execution, and relates to different brain regions. The intensity with which task sets are activated and processed dynamically decreases and increases. The temporal stability of these activations could, however, hardly explain behavioral performance. Instead, task set deactivation processes associated with left orbitofrontal regions and inferior parietal regions selectively acting on motor response task sets are relevant. The study shows how propositions from cognitive theories stressing the importance task set activation/deactivation during cognitive flexibility are implemented on a neurophysiological level.

Dopaminergic modulation of motor network compensatory mechanisms in Parkinson's disease.

The dopaminergic system has a unique gating function in the initiation and execution of movements. When the interhemispheric imbalance of dopamine inherent to the healthy brain is disrupted, as in Parkinson's disease (PD), compensatory mechanisms act to stave off behavioral changes. It has been proposed that two such compensatory mechanisms may be (a) a decrease in motor lateralization, observed in drug-naïve PD patients and (b) reduced inhibition - increased facilitation. Seeking to investigate the differential effect of dopamine depletion and subsequent substitution on compensatory mechanisms in non-drug-naïve PD, we studied 10 PD patients and 16 healthy controls, with patients undergoing two test sessions - "ON" and "OFF" medication. Using a simple visually-cued motor response task and fMRI, we investigated cortical motor activation - in terms of laterality, contra- and ipsilateral percent BOLD signal change and effective connectivity in the parametric empirical Bayes framework. We found that decreased motor lateralization persists in non-drug-naïve PD and is concurrent with decreased contralateral activation in the cortical motor network. Normal lateralization is not reinstated by dopamine substitution. In terms of effective connectivity, disease-related changes primarily affect ipsilaterally-lateralized homotopic cortical motor connections, while medication-related changes affect contralaterally-lateralized homotopic connections. Our findings suggest that, in non-drug-naïve PD, decreased lateralization is no longer an adaptive cortical mechanism, but rather the result of maladaptive changes, related to disease progression and long-term dopamine replacement. These findings highlight the need for the development of noninvasive therapies, which would promote the adaptive mechanisms of the PD brain.

Attention to a threat-related feature does not interfere with concurrent attentive feature selection.

Visual features associated with a task and those that predict noxious events both prompt selectively heightened visuocortical responses. Conflicting views exist regarding how the competition between a task-related and a threat-related feature is resolved when they co-occur in time and space. Utilizing aversive classical Pavlovian conditioning, we investigated the visuocortical representation of two simultaneously presented, fully overlapping visual stimuli. Isoluminant red and green random dot kinematogram (RDK) stimuli were flickered at distinct tagging frequencies (8.57Hz, 12Hz) to elicit distinguishable steady-state visual evoked potentials (ssVEPs). Occasional coherent motion events prompted a motor response (task) or predicted a noxious noise (threat). These events occurred either in the green (task cue), the red (threat cue), or in both RDKs simultaneously. In the initial habituation phase, participants responded to coherent motion of the green RDK with a key press, but no loud noise was presented at any time. Here, selective amplification was seen for the task-relevant (green) RDK, and interference was observed when both RDKs simultaneously showed coherent motion. Upon pairing the threat cue with the noxious noise in the subsequent acquisition phase, the threat cue-evoked ssVEP (red RDK) was also amplified, but this amplification did not interact with amplification of the task cue or alter the behavioral or visuocortical interference effect observed during simultaneous coherent motion. Although competing feature conjunctions resulted in interference in the visual cortex, the acquisition of a bias toward an individual threat-related feature did not result in additional cost effects.

Effect of chiropractic manipulative therapy on reaction time in special operations forces military personnel: a randomized controlled trial

BackgroundChiropractic manipulative therapy (CMT) has been shown to improve reaction time in some clinical studies. Slight changes in reaction time can be critical for military personnel, such as special operation forces (SOF). This trial was conducted to test whether CMT could lead to improved reaction and response time in combat-ready SOF-qualified personnel reporting little or no pain.MethodsThis prospective, randomized controlled trial was conducted at Blanchfield Army Community Hospital, Fort Campbell, KY, USA. Active-duty US military participants over the age of 19 years carrying an SOF designation were eligible. Participants were randomly allocated to CMT or wait-list control. One group received four CMT treatments while the other received no treatment within the 2-week trial period. Assessment included simple hand/foot reaction time, choice reaction time, and Fitts’ Law and whole-body response time. On visits 1 and 5, the same five assessments were conducted immediately pre- and post-treatment for the CMT group and before and after a 10-min wait period for the wait-list group. Primary outcomes included between-group differences for the pre-CMT/wait-list period at visit 1 and visit 5 for each test. Secondary outcomes included between-group differences in immediate pre- and post-(within visit) changes. Analysis of covariance was used for all data analysis.ResultsOne hundred and seventy-five SOF-qualified personnel were screened for eligibility; 120 participants were enrolled, with 60 randomly allocated to each group. Due to technical problems resulting in inconsistent data collection, data from 77 participants were analyzed for simple hand/foot reaction time. The mean ± standard deviation (SD) age was 33.0 ± 5.6 years and all participants were male. No between-group statistically significant differences were found for any of the five biomechanical tests, except immediate pre- and post-changes in favor of the CMT group in whole-body response time at both assessment visits. There were four adverse events, none related to trial participation.ConclusionsA single session of CMT was shown to have an immediate effect of reducing the time required for asymptomatic SOF qualified personnel to complete a complex whole-body motor response task. However, sustained reduction in reaction or response time from five tests compared with a wait-list control group was not observed following three sessions of CMT.Trial registrationClinicalTrials.gov, NCT02168153. Registered on 12 June 2014.

Diminished Risk-Aversion After Right DLPFC Stimulation: Effects of rTMS on a Risky Ball Throwing Task.

Several studies on human risk taking and risk aversion have reported the involvement of the dorsolateral prefrontal cortex (DLPFC). Yet, current knowledge of the neural mechanisms of risk-related decision making is not conclusive, mainly relying on studies using non-motor tasks. Here we examine how modulation of DLPFC activity by repetitive transcranial magnetic stimulation (rTMS) affects risk-taking behavior during a motor response task. One-Hertz rTMS to the right DLPFC was applied to monitor risk-taking and risk-aversion performance during a goal-directed risky task with motor response. Healthy participants were instructed to aim for a high score by throwing a ball as close to the ceiling as possible, while avoiding touching the ceiling with the ball. One-Hertz rTMS stimulation to the right DLPFC significantly increased the frequency of ceiling hits, compared to Sham-stimulation. Our results suggest that the right DLPFC is a valid target for manipulating risky behavior in tasks with a motor-response. Following rTMS stimulation participants' preference shifts toward immediate awards, while becoming significantly less sensitive to potential negative consequences. The results confirm that the right DLPFC is involved in impulse control in goal-directed executive tasks. (JINS, 2019, 25, 72-78).

Profiles of Cognitive-Motor Interference During Walking in Children: Does the Motor or the Cognitive Task Matter?

The evidence supporting the effects of age on the ability to coordinate a motor and a cognitive task show inconsistent results in children and adolescents, where the Dual-Task Effects (DTE) – if computed at all – range from either being lower or comparable or higher in younger children than in older children, adolescents and adults. A feasible reason for the variability in such findings is the wide range of cognitive tasks (and to some extend of motor tasks) used to study Cognitive-Motor Interference (CMI). Our study aims at determining the differences in CMI when performing cognitive tasks targeting different cognitive functions at varying walking pathways. 69 children and adolescents (boys, n = 45; girls, n = 24; mean age, 11.5 ± 1.50 years) completed higher-level executive function tasks (2-Back, Serial Subtraction, Auditory Stroop, Clock Task, TMT-B) in comparison to non-executive distracter tasks [Motor Response Task (MRT), TMT-A] to assess relative effects on gait during straight vs. repeated Change of Direction (COD) walking. DT during COD walking was assessed using the Trail-Walking-Test (TWT). The motor and cognitive DTE were calculated for each task. There were significant differences between 5th and 8th graders on single gait speed on the straight (p = 0.016) and the COD pathway (p = 0.023), but not on any of the DT conditions. The calculation of DTEs revealed that motor DTEs were lowest for the MRT and highest for the TWT in the numbers/letters condition (p < 0.05 for all comparisons). In contrast, there were cognitive benefits for the higher-order cognitive tasks on the straight pathways, but cognitive costs for both DT conditions on the COD pathway (p < 0.01 for all comparisons). Our findings demonstrate that DT changes in walking when completing a secondary task that involve higher-level cognition are attributable to more than low-level divided attention or motor response processes. These results specifically show the direct competition for higher-level executive function resources important for walking, and are in agreement with previous studies supporting the cognitive-motor link in relation to gait in children. This might be in line with the idea that younger children may not have adequate cognitive resources.

Dissociable Response Inhibition in Children With Tourette’s Syndrome Compared With Children With ADHD

Objective: This study investigates whether performance in a verbal response task (Color-Word Interference Test [CWIT]) and a motor response task (Conners’ Continuous Performance Test [CCPT]) discriminates children with Tourette’s Syndrome (TS), ADHD, and typically developing children (TDC). Method: Nineteen children with TS, 79 with ADHD, and 50 with TDC participated (8-17 years). Results: Children with TS committed significantly fewer errors in the verbal response task than those with ADHD. Moreover, children with TS but without ADHD performed better than TDC. Errors in motor task and speed of response did not distinguish between groups. A cautious tendency of response correlated positively with rates of tics in children with TS. Conclusion: Children with TS were superior in inhibiting a prepotent verbal response; however, comorbidity with ADHD in those children negatively influenced performance. Results support the hypothesis that levels of inhibitory control distinguish children with TS, ADHD, and TDC.

Dual-task and electrophysiological markers of executive cognitive processing in older adult gait and fall-risk.

The role of cognition is becoming increasingly central to our understanding of the complexity of walking gait. In particular, higher-level executive functions are suggested to play a key role in gait and fall-risk, but the specific underlying neurocognitive processes remain unclear. Here, we report two experiments which investigated the cognitive and neural processes underlying older adult gait and falls. Experiment 1 employed a dual-task (DT) paradigm in young and older adults, to assess the relative effects of higher-level executive function tasks (n-Back, Serial Subtraction and visuo-spatial Clock task) in comparison to non-executive distracter tasks (motor response task and alphabet recitation) on gait. All DTs elicited changes in gait for both young and older adults, relative to baseline walking. Significantly greater DT costs were observed for the executive tasks in the older adult group. Experiment 2 compared normal walking gait, seated cognitive performances and concurrent event-related brain potentials (ERPs) in healthy young and older adults, to older adult fallers. No significant differences in cognitive performances were found between fallers and non-fallers. However, an initial late-positivity, considered a potential early P3a, was evident on the Stroop task for older non-fallers, which was notably absent in older fallers. We argue that executive control functions play a prominent role in walking and gait, but the use of neurocognitive processes as a predictor of fall-risk needs further investigation.

Hippocampal and striatal dependent navigation: Sex differences are limited to acquisition

Estrogen has been demonstrated to enhance the use of hippocampal-based place learning while reducing the use of striatal-based motor-response strategy (Korol, D.L., Malin, E.L., Borden, K.A., Busby, R.A., & Couper-Leo, J. (2004). Shifts in preferred learning strategy across the estrous cycle in female rats. Horm. Behav. 45, 330–338). Previous research has focused on task acquisition and the switch from a place to motor-response navigation with training. The current paradigm allowed an examination of the interplay between these two systems by having well-trained animals switch strategies “on demand.” Female and male Sprague–Dawley rats were taught a motor-response task on a plus maze. The rats were then introduced to a place task and taught to switch, by cue, from the motor-response to place strategy. Finally, the rats were trained to continuously alternate between place and motor-responses strategies. The maze configuration allowed for an analysis of cooperative choices (both strategies result in the same goal arm), competitive choices (both strategies result in different goal arms), and single strategy choices (can only use the motor-response strategy). The results indicate that sex and estrogen-related effects on navigation strategy are limited to the initial stages of learning a task. The role of sex and estrogen is diminished once the task is well learned, and presumably, the relative involvement of the hippocampal and striatal systems is established.

Effect of methamphetamine neurotoxicity on learning-inducedarc mRNA expression in identified striatal efferent neurons

Methamphetamine abuse results in lasting, partial depletions of striatal dopamine and cognitive dysfunction. However, the effect of partial dopamine depletions on the expression of an effector immediate early gene, Arc (activity regulated, cytoskeletal-associated protein), known to be involved in synaptic modifications underlying learning and memory, has heretofore not been examined. Male Sprague-Dawley rats were pretreated with a neurotoxic regimen of methamphetamine or saline. Seven weeks later, rats were trained in a motor-response task on a T-maze for five days, and then underwent reversal training on day five. Rats were sacrificed 5 min after reaching criterion on the reversal task, and the brains were removed and processed using double-label fluorescent in situ hybridization for Arc and preproenkephalin (PPE) mRNA expression in the dorsomedial striatum. Rats pretreated with methamphetamine had an average (+/-SEM) 54.4+/-7.9% loss of dopamine in dorsomedial striatum. Interestingly, there was no difference in reversal trials to criterion in methamphetamine- vs. saline-pretreated rats. However, the expression of Arc mRNA in dorsomedial striatum was attenuated in methamphetamine-pretreated animals, particularly in PPE-negative neurons. Furthermore, the correlation between Arc mRNA expression in dorsomedial striatum and learning was abolished in methamphetamine-pretreated animals. These data suggest that methamphetamine-induced partial monoamine loss is associated with disrupted induction of the effector immediate early gene Arc during a behavioral task, particularly in PPE-negative (presumed striatonigral) neurons, as well as with disruption of the relation between Arc mRNA expression in dorsomedial striatum and reversal learning.

Does photoparoxysmal response in children represent provoked seizure? Evidence from simultaneous motor task during EEG

Objectives Acute cognitive changes during epileptiform discharges have been studied using computer assisted cognitive tasks. We aimed to demonstrate acute behavioral change (using a simple motor response task MRT) during photoparoxysmal response (PPR) in children below 18 years. Methods Children performed a simple repetitive motor task during intermittent photic stimulation (IPS). All episodes of PPR not associated with obvious clinical change (as observed by the technologist or reported by the patient) were analyzed for this study. The average time interval between two successive motor responses across a PPR (test time) was compared to the average time interval between two successive motor responses during IPS not associated with PPR (control time) using Wilcoxon signed ranks test. Results 21 children who had PPR successfully completed the MRT. The difference between the mean durations was 0.894 s ( p = 0.002). More than 50% increase compared to the control time was considered a delay in MRT during PPR. 10 children showed slowing of MRT during PPR. Conclusion By definition, acute behavioral change during generalized epileptiform discharges represent provoked seizures. Detecting subclinical seizures can have important safety implications in children (skiing, skating and driving) with PPR on EEG, but no clinical seizures. We recommend MRT during IPS.

Arc mRNA induction in striatal efferent neurons associated with response learning

The dorsal striatum is involved in motor-response learning, but the extent to which distinct populations of striatal efferent neurons are differentially involved in such learning is unknown. Activity-regulated, cytoskeleton-associated (Arc) protein is an effector immediate-early gene implicated in synaptic plasticity. We examined arc mRNA expression in striatopallidal vs. striatonigral efferent neurons in dorsomedial and dorsolateral striatum of rats engaged in reversal learning on a T-maze motor-response task. Male Sprague-Dawley rats learned to turn right or left for 3 days. Half of the rats then underwent reversal training. The remaining rats were yoked to rats undergoing reversal training, such that they ran the same number of trials but ran them as continued-acquisition trials. Brains were removed and processed using double-label fluorescent in situ hybridization for arc and preproenkephalin (PPE) mRNA. In the reversal, but not the continued-acquisition, group there was a significant relation between the overall arc mRNA signal in dorsomedial striatum and the number of trials run, with rats reaching criterion in fewer trials having higher levels of arc mRNA expression. A similar relation was seen between the numbers of PPE(+) and PPE(-) neurons in dorsomedial striatum with cytoplasmic arc mRNA expression. Interestingly, in behaviourally activated animals significantly more PPE(-) neurons had cytoplasmic arc mRNA expression. These data suggest that Arc in both striatonigral and striatopallidal efferent neurons is involved in striatal synaptic plasticity mediating motor-response learning in the T-maze and that there is differential processing of arc mRNA in distinct subpopulations of striatal efferent neurons.

Emotion at the expense of cognition: Psychopathic individuals outperform controls on an operant response task.

The impact of emotional stimuli on a simple motor response task in individuals with psychopathy and comparison individuals was investigated. Psychopathy was assessed using the Psychopathy Checklist Revised (Hare, 1991). Participants were presented with the Emotional Interrupt Task, in which they responded with left and right button presses to shapes that were temporally bracketed by positive, negative, and neutral visual images taken from the International Affective Picture System. The comparison group showed increased response latencies if the shape was temporally bracketed by either a positive or negative emotional stimulus relative to a neutral stimulus. Individuals with psychopathy did not show this modulation of reaction time for either positive or negative emotional stimuli. Results are discussed with reference to current models regarding the modulation of attention by emotion and the emotional impairment seen in individuals with psychopathy.

Investigating directed influences between activated brain areas in a motor-response task using fMRI

Localization of cognitive processes is a strength of functional neuroimaging. However, information about functional interactions between brain areas is crucial for a deeper understanding of brain function. We applied vector autoregressive modeling in the context of Granger causality as a method to analyze directed connectivity in a standard event-related fMRI study using a simple auditory-motor paradigm. The basic idea is to use temporal information in stochastic time series of a brain region in order to predict signal time courses in other brain regions. Thus, we predicted that the method should demonstrate causal influence of the auditory cortex and the supplementary motor area (SMA) on primary motor cortex. Eleven right-handed healthy female subjects were instructed to press a ball with either their left or their right hand when hearing the command "left" or "right" in the scanner. Influence to the left motor cortex was found from bilateral auditory cortex as well as from the SMA in 9 of 11 subjects. Granger causality to the right motor cortex existed from bilateral auditory cortex in 5 and from SMA in 6 subjects. Granger causality to the SMA existed from right auditory cortex in 7 subjects and from left auditory cortex in 8 subjects. Our findings in a simple task show that even under suboptimal circumstances (a relatively long TR of 2440 ms), Granger causality can be a useful tool to explore effective connectivity. Temporally optimized scanning should increase that potential.

Age-related trends in Stroop and conflicting motor response task findings

Inhibition problems are reportedly at the heart of several childhood pathologies and learning disorders, but few instruments are available for their in-depth investigation. The main aim of the present study was to investigate the development of a capacity to inhibit automatic responses in young and middle childhood. For this purpose, 100 children between 6 and 11 years old were administered two tests that measure executive inhibition: an animal Stroop task (in a paper-and-pencil version of the computerized original proposed by Wright and colleagues in 2003) and a conflicting motor response task. Our results indicate that performance clearly improves in both tests during the course of a child's development and the data obtained with the paper-and-pencil animal Stroop task overlap with those obtained with the computerized version. When the task calls for a stronger inhibitory control (the incongruent situation in the Stroop task and in the opposite condition in the conflicting motor response test) the trend of the response times is less homogeneous, peaking in the youngest and oldest age brackets considered. The positivity and significance of the correlation coefficients between the two tests also suggest that the two measures are tapping cognitive abilities that are developing in a parallel fashion.

At attention and intention

Attention is so closely bound to eye movement that saying ‘look’ is often tantamount to saying ‘pay attention’. Orienting one's visual attention often involves shifting one's gaze from one thing to another, but it can in the absence of overt eye movement, in other words, covertly. But could we also covertly orient our intentions in the same way that we covertly orient our attention?Recent studies by Rushworth et al., using both event-related fMRI 1xAttention systems and the organization of the human parietal cortex. Rushworth, M.F.S. et al. J. Neurosci. 2001; 21: 5262–5271PubMedSee all References1 and PET imaging 2xThe attentional role of the left parietal cortex: the distinct lateralization and localization of motor attention in the human brain. Rushworth, M.F.S. et al. J. Cogn. Neurosci. 2001; 13: 698–710Crossref | PubMed | Scopus (229)See all References2, support the idea of covert intentional orienting processes, or ‘motor attention’, and their results suggest that covert visual attention and motor attention play similar roles in their respective modalities. Just as covert visuospatial orienting involves a shift of attention from one part of the visual field to another without making any overt eye movements, visuomotor attention can be thought of as involving a shift of intention from one potential limb movement to another before selecting a response. The experiments by Rushworth and colleagues have indicated that motor attentional processes are anatomically distinct from visuospatial attentional processes. Covert visual attention activates regions of the parietal lobe, an area that is responsible for spatial processing and sensorimotor integration; covert motor attention relies on parietal processing as well, but activates different areas from those involved in visual attentional orientation.In the fMRI experiment 1xAttention systems and the organization of the human parietal cortex. Rushworth, M.F.S. et al. J. Neurosci. 2001; 21: 5262–5271PubMedSee all References1, Rushworth et al. used two related tasks that required subjects to shift their attention from one stimulus feature to another. In the first task, subjects were asked to select the appropriate stimulus by simply attending to it visually; in the second, they had to select their response by pressing a button with the right or left hand. The second condition was designed to isolate activity associated with motor attentional shifts – or ‘intention-switching’ – from that associated with visual attentional shifts. The researchers found that the locations of parietal activity associated with the purely visual task coincided very little with those associated with the motor response task, indicating that visual attention and visuomotor attention are subserved by two dissociable processes in the brain.The PET study 2xThe attentional role of the left parietal cortex: the distinct lateralization and localization of motor attention in the human brain. Rushworth, M.F.S. et al. J. Cogn. Neurosci. 2001; 13: 698–710Crossref | PubMed | Scopus (229)See all References2 revealed another contrast between visual attention and motor attentional activity. Visuospatial attentional systems are distributed throughout the right parietal and frontal cortices. The distinct motor attentional activity revealed by these experiments was, on the other hand, restricted to the left hemisphere. In particular, a left parietal area previously implicated in motor preparation showed significant activity. Left prefrontal areas active in action perception, motor imagery and copying tasks were also active in the motor attention tasks. This suggests a specialization for these visuomotor circuits in the left hemisphere. It also emphasizes the close relationship between attention and intention in the selection of actions. Are the two processes more similar than we usually think? These studies suggest that, although the brain mechanisms of visual orienting and motor orienting are distinct, covert attention and intention nevertheless share a functional logic at this level of processing. The authors’ elucidation of motor attention could help to resolve previous confounds between visual and motor attention, and inform future research on the tightly linked systems underlying perception and action, attention and intention.

Pilot response in combined control tasks.

Pilot response in a multi-task simulation, which consisted of a primary control task combined with one or two secondary or side control tasks, was investigated. A general description of the response characteristics of each of these tasks was obtained and this information was used to determine the work-load requirements of the tasks. Two different control tasks were used as the primary control task, either a fixed-base simulation of a lunar letdown or a simplified multi-loop tracking task which was similar to the end portion of the lunar letdown. The simplified tracking task was used in lieu of the more complicated lunar letdown because it could be represented and reproduced analytically. The secondary or side tasks consisted of a system failures task and a motor response task. The system failures task was incorporated from those systems present in a vehicle known as the Mercury Procedures Trainer. The motor response task was similar to that presented by the late Dr. Fitts of the University of Michigan. The task consisted of using a pencil-like device to make impacts on two separated, restricted columns. An evaluation of the pilot's capability in controlling the multi-task simulation and a determination of the inter-task correlation was made. It was shown that either of the two side tasks produced similar effects on the primary task. Quality measurements were made of all three tasks in all possible combinations. The degradation of each, when in the combined task tests, was then correlated to the other task(s) of the same test. A simple relationship was found by which one could predict the time required of a human operator to perform the particular task(s) in question. This relationship could be used to determine the workloading qualities of the tasks when performed either alone or combined. An analytical representation for the degraded pilot response in the multi-loop tracking task was also obtained.