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Misdirected attentional focus in functional tremor.

ABSTRACT: A characteristic and intriguing feature of functional neurological disorder is that symptoms typically manifest with attention and improve or disappear with distraction. Attentional phenomena are therefore likely to be important in functional neurological disorder, but exactly how this manifests is unknown. The aim of the study was to establish whether in functional tremor the attentional focus is misdirected, and whether this misdirection is detrimental to the movement, or rather reflects a beneficial compensatory strategy. Patients with a functional action tremor, between the ages of 21-75, were compared to two age and gender matched control groups: healthy control participants and patients with an organic action tremor. The groups included between 17 and 28 participants. First, we compared the natural attentional focus on different aspects of a reaching movement (target, ongoing visual feedback, proprioceptive-motor aspect). This revealed that the attentional focus in the functional tremor group, in contrast to both control groups, was directed to ongoing visual feedback from the movement. Next, we established that all groups were able to shift their attentional focus to different aspects of the reaching movement when instructed. Subsequently, the impact of attentional focus on the ongoing visual feedback on movement performance was evaluated under several conditions: the reaching movement was performed with direct, or indirect visual feedback, without any visual feedback, under three different instruction conditions (as accurately as possible/very slowly/very quickly) and finally as a preparatory movement that was supposedly of no importance. Low trajectory length and low movement duration were taken as measures of good motor performance. For all three groups, motor performance deteriorated with attention to indirect visual feedback, to accuracy and when instructed to move slowly. It improved without visual feedback and when instructed to move fast. Motor performance improved, in participants with functional tremor only, when the movement was performed as a preparatory movement without any apparent importance. In addition to providing experimental evidence for improvement with distraction, we found that the normal allocation of attention during aimed movement is altered in functional tremor. Attention is disproportionately directed towards the ongoing visual feedback from the moving hand. This altered attentional focus may be partly responsible for the tremor, since it also worsens motor performance in healthy control participants and patients with an organic action tremor. It may have its detrimental impact through interference with automatic movement processes, due to a maladaptive shift from lower- to higher-level motor control circuitry.

SUBMITTER: Huys AML

PROVIDER: S-EPMC8677517 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Maintaining an external direction of focus during practice is reported to facilitate acquisition of non-speech motor skills, but it is not known whether these findings also apply to treatment for speech errors. This question has particular relevance for treatment incorporating visual biofeedback, where clinician cueing can direct the learner's attention either internally (i.e., to the movements of the articulators) or externally (i.e., to the visual biofeedback display).This study addressed two objectives. First, it aimed to use single-subject experimental methods to collect additional evidence regarding the efficacy of visual-acoustic biofeedback treatment for children with /r/ misarticulation. Second, it compared the efficacy of this biofeedback intervention under two cueing conditions. In the external focus (EF) condition, participants' attention was directed exclusively to the external biofeedback display. In the internal focus (IF) condition, participants viewed a biofeedback display, but they also received articulatory cues encouraging an internal direction of attentional focus.Nine school-aged children were pseudo-randomly assigned to receive either IF or EF cues during 8 weeks of visual-acoustic biofeedback intervention. Accuracy in /r/ production at the word level was probed in three to five pre-treatment baseline sessions and in three post-treatment maintenance sessions. Outcomes were assessed using visual inspection and calculation of effect sizes for individual treatment trajectories. In addition, a mixed logistic model was used to examine across-subjects effects including phase (pre/post-treatment), /r/ variant (treated/untreated), and focus cue condition (internal/external).Six out of nine participants showed sustained improvement on at least one treated /r/ variant; these six participants were evenly divided across EF and IF treatment groups. Regression results indicated that /r/ productions were significantly more likely to be rated accurate post- than pre-treatment. Internal versus external direction of focus cues was not a significant predictor of accuracy, nor did it interact significantly with other predictors.The results are consistent with previous literature reporting that visual-acoustic biofeedback can produce measurable treatment gains in children who have not responded to previous intervention. These findings are also in keeping with previous research suggesting that biofeedback may be sufficient to establish an external attentional focus, independent of verbal cues provided. The finding that explicit articulator placement cues were not necessary for progress in treatment has implications for intervention practices for speech-sound disorders in children.

Project description:BackgroundThe impact of high distraction, real-world environments on dual-task interference and flexibility of attentional prioritization during dual-task walking in people with stroke is unknown.Research questionHow does a real-world environment affect dual-task performance and flexible task prioritization during dual-task walking in adults with and without stroke?MethodsAdults with stroke (n = 29) as well as age-, gender-, and education-matched adults without stroke (n = 23) participated. Single and dual-task walking were examined in two different environments (lab hallway, hospital lobby). Two different dual-task combinations were assessed (Stroop-gait, speech-gait). Each dual-task was performed first without explicit instruction about task prioritization (no-priority) and then with gait-priority instruction and Stroop/speech-priority instruction in randomized order.ResultsPeople with stroke had significantly slower dual-task gait speed (Stroop only) in the lobby than the lab, but the effect was not clinically meaningful. Stroop reaction time for all participants was also slower in the lobby than the lab. All participants slowed their walking speed while generating spontaneous speech, but this effect was not influenced by environment. The dual-task attention allocation strategy was generally inflexible to instructed prioritization in adults with and without stroke in both environments, however, the volitional attention allocation strategy differed for the two dual-task conditions such that speech was prioritized in the speech-gait dual-task and gait appeared to be prioritized in the Stroop-gait dual-task.SignificanceAlthough dual-tasking slows walking speed and verbal responses to auditory stimuli in people with stroke, the effects are not considerably impacted by a more complex, distracting environment. Adults with and without stroke may have difficulty overriding the preferred attention allocation strategy during dual-task walking, especially for habitual dual-tasks such as walking while speaking. It may also be that the cognitive control strategy governing task prioritization is influenced by degree of cognitive engagement.

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Misdirected attentional focus in functional tremor.

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