Continuous Perseveration Research Articles

Comparative Roles of the Caudate and Putamen in the Serial Order of Behavior: Effects of Striatal Glutamate Receptor Blockade on Variable versus Fixed Spatial Self-Ordered Sequencing in Marmosets.

Self-ordered sequencing is an important executive function involving planning and executing a series of steps to achieve goal-directed outcomes. The lateral frontal cortex is implicated in this behavior, but downstream striatal outputs remain relatively unexplored. We trained marmosets on a three-stimulus self-ordered spatial sequencing task using a touch-sensitive screen to explore the role of the caudate nucleus and putamen in random and fixed response arrays. By transiently blocking glutamatergic inputs to these regions, using intrastriatal CNQX microinfusions, we demonstrate that the caudate and putamen are both required for, but contribute differently to, flexible and fixed sequencing. CNQX into either the caudate or putamen impaired variable array accuracy, and infusions into both simultaneously elicited greater impairment. We demonstrated that continuous perseverative errors in variable array were caused by putamen infusions, likely due to interference with the putamen's established role in monitoring motor feedback. Caudate infusions, however, did not affect continuous errors, but did cause an upward trend in recurrent perseveration, possibly reflecting interference with the caudate's established role in spatial working memory and goal-directed planning. In contrast to variable array performance, while both caudate and putamen infusions impaired fixed array responding, the combined effects were not additive, suggesting possible competing roles. Infusions into either region individually, but not simultaneously, led to continuous perseveration. Recurrent perseveration in fixed arrays was caused by putamen, but not caudate, infusions. These results are consistent overall with a role of caudate in planning and flexible responding and the putamen in more rigid habitual or automatic responding.

P61: The use of the errorless learning method in the rehabilitation of activities of daily living and instrumental activities of daily living

Objective:The aim of this review was to describe the usage and effectiveness of errorless learning in activities of daily living (ADL) and instrumental activities of daily living (IADL) rehabilitation methods reported in the literature over the past 10 years.Methods:Two databases were searched (PubMed, EMBASE) using the key words “errorless learning and ADL and IADL”. Articles published in the last 10 years in English were considered.Results:4 studies were identified that included 94 people with Alzheimer's disease (AD) and 129 people with stroke (104 with amnesia and 25 with ideational apraxia ).One study on AD patients showed that it is possible for them to re-learn relevant IADL activities using the errorless learning (EL) and spaced retrieval (SR) techniques and to maintain these gains for at least 3 months (t =2.811; df =22.246; p=0.010).In another study on AD patients, participants with AD had to re-learn three IADLs. All three learning methods (including EL) had similar efficiency (F(2,94)=21,99). However, the intervention resulted in greater improvement in actual IADL task performance than in explicit knowledge.In another study, structured ADL re-training in stroke survivors with amnesia significantly increased functional independence (MD: 4.90, SE=1.4, 95% confidence interval) and shortened time of hospitalisation (mean difference: 5.22, SE= 1.4, 95% CI: 1.8, 8.7).The fourth study presented a model in which patients with post-stroke ideational apraxia attended tea making training sessions during which progress was monitored and feedback was provided via a computer system. A qualitative analysis of errors was conducted before training, and the most common errors observed were those related to kettlebell and continuous perseveration. After training, the frequency of errors decreased for all error types except for skipping a step.Conclusion:The results of the studies discussed demonstrate the wide range of applications of error-free learning protocols in both AD patients and post-stroke patients. A clearly specified but flexible training protocol, together with information on error distribution, provide pointers for further refinement of task model approaches in ADL and IADL rehabilitation.

When Palestine Shook

Sparked by Israeli repression and ethnic cleansing campaigns in Jerusalem, the uprising of May 2021 featured a widescale mobilization that activated Palestinians across the entirety of the country. What brought about this moment and what was its impact? In this essay, I reflect on the historical moment that has become known to many as the “Unity Intifada” and how it highlighted the continued perseverance and oneness of the Palestinian people while simultaneously indicting their leadership. In a matter of weeks, Palestinians demonstrated that they retained the capacity to create change, notwithstanding the limitations of such change thanks to the ineffectual leadership class.

Evaluating mentoring outcomes from the perspective of entrepreneurs and small business owners

Background: Mentoring as support for both the business and the individual entrepreneur or small business owner is important for the continued perseverance of the entrepreneurial journey.Aim: Different mentoring outcomes were evaluated to establish what is being gained from the mentoring relationships to encourage other entrepreneurs and small business owners to pursue mentoring relationships.Setting: South African entrepreneurs and small business owners who were currently being mentored or had been mentored.Method: The study used a survey research design that consisted of 209 qualifying entrepreneurs and small business owners. An online questionnaire was used to collect the data.Results: The results show that there is a relationship between the different mentoring outcomes (skills transfer outcomes, knowledge transfer outcomes, entrepreneur resilience outcomes and business outcomes). In addition, it was established that as the mentoring relationship goes through the different phases of initiation, cultivation, separation and redefinition, mentoring outcomes such as skills transfer and entrepreneur resilience are independently attained.Conclusion: Understanding the outcomes of mentoring will encourage more participation in the field of mentoring for South African mentors, entrepreneurs and small business owners through awareness of the benefits thereof as well as how mentoring can form a strong supporting mechanism. This research makes a theoretical contribution by naming and grouping mentoring outcomes into four categories, such as skills transfer outcomes, knowledge transfer outcomes, entrepreneur resilience outcomes and business outcomes.

Getting gritty about practice and success: Motivational characteristics of great performers.

We consider the data reported in the target article with respect to key motivational frameworks and characteristics, including grit and self-determined forms of motivation. Empirical data are reviewed that highlight the relationships between these concepts and practice and success. We highlight the concept of grit as a defining characteristic of the super-elite athletes, in reference to both their continued perseverance in the face of obstacles, as well as the increased motivation seemingly caused by such obstacles or setbacks. We discuss the dynamic nature of motivation with respect to cross-sectional and longitudinal age-related comparisons in athletes. Such research is necessary to better understand the characteristics that are potentially transitory or that are a consequence of success, rather than being causal in nature. In the final section, we provide evidence consistent with a profile of a super-elite athlete that is best defined with respect to coexisting types of motivations that have traditionally been considered both positive and negative with respect to their outcomes. The between group comparisons of highly successful athletes in the target article, is unusual yet important if we are to better understand the psychosocial profiles necessary to succeed, that are unbiased by age, practice, and competition experience.

Unilateral Perseverationnnn

The brain's action-intentional ("when") programming system helps to control when to and when not to initiate an action, when to persist at an action, and when to terminate an action. Motor perseveration is a failure to terminate an action. This disengagement disorder most often results from dysfunction of the executive frontal-subcortical networks that control the action-intentional programming system. Reports of unilateral perseveration are unusual. Here we describe a patient with a form of progressive supranuclear palsy (PSP) who exhibited continuous right-hand motor perseveration. This 68-year-old right-handed man had impaired walking and vertical gaze, consistent with PSP. He often repeated words, and on many motor tasks he showed continuous perseveration of his right but not his left hand. Unilateral motor perseveration may be a sign of PSP, the corticobasal syndrome, or a subtype of these disorders. Future studies of patients with both disorders should use tasks that assess for asymmetric hand perseveration. The mechanism of the unilateral perseveration must also be determined. Bilateral perseveration is found most often in patients with unilateral right frontal-subcortical (basal ganglia) or insula dysfunction. Because patients with PSP or corticobasal syndrome have callosal degeneration, their unilateral perseveration might result from a callosal disconnection of the right frontal lobe from the left hemisphere's premotor and motor as well as speech areas.

Unusual Presentation, Common Disease

A 65-year-old right-handed woman with a history of hypertension, remote tobacco use, depression, and anxiety presented to our hospital with acute onset of bilateral flinging arm movements and speech arrest witnessed by her boyfriend. She arrived at the emergency department (ED) within 1 hour of the symptom onset. On examination, she was hypertensive with a normal heart rate and temperature. She was awake and alert and only followed commands when asked to raise her legs. She mimicked eye closure and raised 2 fingers in both the hands. She had very little to no spontaneous speech and only answered questions with different random numbers throughout her stay in the ED. During attempts to name a pen or knuckles, she only verbalized numbers; reading and writing were not assessed. On cranial nerve examination, there was a slight right central facial nerve palsy. She moved all limbs equally against gravity. The flinging arm movements had resolved upon arrival at the ED. Her sensory examination was grossly normal as she withdrew her limbs to noxious stimulation, and her National Institutes of Health Stroke Scale (NIHSS) was 7. Noncontrast computed tomography (CT) of the head was unremarkable, and seizure was suspected because of the acute onset of arm movements for short duration and a possible postictal state with perseveration. However, CT angiography revealed a distal left M1 middle cerebral artery thrombus, and intravenous recombinant tissue plasminogen activator was administered. Subsequent brain magnetic resonance imaging (Figure 1) showed acute, patchy infarctions in the left basal ganglia, temporal, parietal, and frontal lobes, as well as a small left thalamic infarct. Over the next few days, the patient’s aphasic syndrome evolved into a mixed expressive and receptive aphasia, and she was discharged to rehabilitation for further speech therapy. Figure 1. Diffusion-weighted magnetic resonance imaging (MRI) image showing patchy restricted diffusion in the middle cerebral artery (MCA) and posterior cerebral artery (PCA) territories. The initial presentation of acute and transient bilateral motor activity suggested an epileptic event rather than stroke. However, only a small minority of strokes (0.3% in one study) present with seizure at onset.1 Alternatively, our patient’s bilateral arm movement may have been the result of infarction of the basal ganglia, though in this case only the left basal ganglia was affected. Although uncommon (about 1% in the Lausanne Stroke Registry), movement disorders (eg, ballism, dystonia, myoclonus, and tremor) can present acutely in the setting of stroke.2 A wide range of localizations have been cited including most commonly lesions of the basal ganglia and subthalamic nucleus. Other less common location of infarcts causing ballism include the thalamus, parieto-occipital areas and internal capsule, and areas involving both the anterior and the posterior circulation.3 Our patient’s aphasic syndrome consisted of perseveration only on different random numbers in response to all questions. Perseveration has long been a topic of interest to neurologists. In 1984, Sandson and Albert presented a new taxonomy of perseveration of speech: stuck-in-set, recurrent, and continuous. Stuck-in-set perseveration, defined as “inappropriate maintenance of a current category,” is seen in patients with dementia who, for instance, repeat numbers in the presented order when asked to repeat them backward. Continuous perseveration is the “inappropriate repetition, without interruption, of a current behavior.” This is exemplified in patients with subcortical injury.4 Recurrent perseveration is common in patients with aphasia caused by dominant hemispheric lesions. It is manifested by the repetition of a previous response after new stimulus is presented.5 Sandson and Albert later proposed that recurrent perseveration is based on left hemispheric temporal–parietal lesions, continuous perseveration is due to right hemispheric lesions, and stuck-in-set perseveration is due to frontosubcortical/mesolimbic lesions.4 Recent studies have noted perseveration resulting from lesions to the caudate head6 as well as the left supplementary motor area, basal ganglia, midbrain, and thalamus.7 Aphasias with sparing of number words have been described by Bencini et al. In their work, they studied a patient with left posterior temporal stroke who developed aphasia with error-free production of number words but with significant difficulty in uttering nonnumber words. They proposed linguistic reasons for the dissociation of number and nonnumber words, but a definitive mechanism and localization remain elusive.8 This case of patchy anterior and posterior circulation strokes demonstrates the sometimes unusual presentation of symptoms in patients with stroke. We hope this adds to the neurohospitalist’s understanding of acute vascular pathology.

Possible roles of the dominant uncinate fasciculus in naming objects: a case report of intraoperative electrical stimulation on a patient with a brain tumour.

How the dominant uncinate fasciculus (UF) contributes to naming performance is uncertain. In this case report, a patient with an astrocytoma near the dominant UF was given a picture-naming task during intraoperative electrical stimulation in order to resect as much tumourous tissues as possible without impairing the dominant UF function. Here we report that the stimulations with the picture-naming task also provided some insights into how the dominant UF contributes to naming performance. The stimulation induced naming difficulty, verbal paraphasia, and recurrent and continuous perseveration. Moreover, just after producing the incorrect responses, the patient displayed continuous perseveration even though the stimulation had ended. The left UF connects to the inferior frontal lobe, which is necessary for word production, so that the naming difficulty appears to be the result of disrupted word production caused by electrical stimulation of the dominant UF. The verbal paraphasia appears to be due to the failure to select the correct word from semantic memory and the failure to suppress the incorrect word. The left UF is associated with working memory, which plays an important role in recurrent perseveration. The continuous perseveration appears to be due to disturbances in word production and a failure to inhibit an appropriate response. These findings in this case suggest that the dominant UF has multiple roles in the naming of objects.

How many movements in a scribble? A method for quantifying “continuous” perseveration in cancellation tasks

SCRIBBLES IN CANCELLATION TASKS Neglect patients often show perseveration while crossing out targets in a paper-andpencil cancellation task (e.g., Na et al., 1999; Bottini and Toraldo, 2003; Toraldo et al., 2005). Thus they may cancel a target by producing more than one mark, or by carrying out a continuous, uninterrupted movement which produces a scribble rather than a well-formed, simple mark (“continuous perseveration,” Sandson and Albert, 1984, 1987). The topic has been debated with growing interest in the last few years, especially regarding the problem of whether perseveration intensity correlates with neglect severity: some authors reported a significant, positive correlation (e.g., Na et al., 1999; Nys et al., 2006), some others failed to find it (e.g., Pia et al., 2009; Ronchi et al., 2009). Settling such an issue would be relevant to decide whether the two deficits share some underlyingmechanisms (e.g., Posner et al., 1984; Toraldo et al., 2005), or are functionally independent (e.g., Ronchi et al., 2009). I reasoned that part of the discrepancies between results in the literature might be due to differences in the grain of analysis of perseverative behaviors, with coarsegrained methods failing to detect effects that were instead found by finer-grained methods. Hence in this paper I will propose a fine-grain analysis yielding a very sensitive measure of one specific perseveration type, i.e., scribbling behavior. The ideal measure of scribbling behavior would be a count of the (linear or circular) movements that were performed to produce the scribble. The use of highdefinition cameras for filming the patient’s performance (Kim et al., 2009), or of graphic tablets to record it, is not always possible or practical, especially in clinical settings (patients with marked perseverative symptomatology are most typically in the acute phase), and might interfere with natural motor behavior by the patient. Indeed, virtually all studies in the field were retrospective analyses of cancellation marks produced on paper sheets. The purpose of the present work is to develop a retrospective method that, given a scribble, allows one to obtain a proxy of the number N of movements that were made to produce it, even though no video recording of the performance is available. This would allow the experimenter to perform a fine-grain analysis of scribbling behavior on much larger patient samples, thus increasing statistical power.

Designing a robotic colorectal program.

Designing a successful robotic colorectal program requires consideration and implementation of several important concepts with continued perseverance through many obstacles that may arise. The ideal strategy is to establish a core group of committed individuals, define the goals and vision of the program, enlist corporate partners, and gain financial support with a sound business, educational, and research plan. Factors such as cost, limited availability, and demanding training are often hindrances to the implementation of a new robotic colorectal program while scheduling conflicts and inadequate resources may present obstacles to developing a colorectal program in institutions with existing robotic surgical programs. In developing a business plan one should consider the potential for increased patient referrals and the benefits of reduced hospital stay, decreased infection and complication rates, and quicker recovery compared with open surgical procedures. The optimal robotics surgical staff will include those most eager to be trained, as they are highly motivated and have the greatest enthusiasm to succeed. The early foundation of accomplishment will be vital to the long-term success of the program. In addition to building the ideal surgical team, patient selection is one of the most crucial considerations in developing a successful robotics program. Initiating a positive impression for robotic-assisted laparoscopic colorectal procedures will be an important precursor to continued success. Likewise, maintaining a regular schedule of procedures may advance the team's competencies and deter complacency. Proper planning, deliberate implementation, and sustained perseverance are key to the successful initiation of a robotic colorectal program.

SUCCESSFUL MANAGEMENT OF INTRACTABLE INFECTION AFTER LIMB-SAVING SURGERY: A CASE REPORT

Infections following limb-saving surgeries still happen frequently and are refractory to treatment, even though the treatment of massive bone defects caused by bone resection of bone tumors has improved gradually. Once infections become intractable, they generally result in amputations in spite of all kinds of treatment. We report the case of a patient who developed an intractable infection after limb-saving surgery utilizing a massive frozen autograft and a tumor prosthesis, but whose limb was finally successfully salvaged by multiple surgical interventions. We conclude that continued perseverance in treatment after infections may enable preservation of the limb and restoration of good function.

Gene therapy for disc repair

Background context Recent advances in our understanding of the biologic makeup and environment of the intervertebral disc (IVD) have led to increased interest in the development of novel treatments for disc degeneration. Certain genes found to alter rates of matrix synthesis and catabolism within the disc have provided targets for scientists seeking to alter the balance between the two. To this end, gene therapy has emerged as a potential therapeutic option, and recent research efforts have yielded very promising results. Purpose To update and consolidate information regarding the recent advances in gene therapy and its application to IVD degeneration. Study design/setting Review of recent and ongoing research in the field of gene therapy, particularly regarding its application to the treatment of IVD degeneration. Methods Literature review. Results With its unique ability to provide sustained delivery of potentially therapeutic agents, gene therapy has shown much promise with regard to the treatment of IVD degeneration. There have been many exciting developments such as safer and more reliable vector constructs, favorable results using therapeutic transgenes in disc cells both in vitro and in vivo, and improvement in transgene regulation, and investigators continue to explore ways in which gene therapy can become a powerful tool in the future treatment of disc degeneration. Conclusions With continued perseverance and dedication, many advances have been made in the application of gene therapy to the IVD, and it continues to demonstrate great potential to become a powerful tool in the future treatment of disc degeneration.

Is a Perseveration a Perseveration? An Evaluation of Cognitive Error Types in Patients with Subcortical Pathology

This study investigated several constructs of executive functioning in a group of 77 patients with subcortical pathology. Specifically, we examined the validity of categorizing perseverative errors as “recurrent,” “stuck-in-set,” or “continuous,” as proposed by Sandson and Albert (1984). A principal components analysis of 2 measures of recurrent perseveration, 2 measures of stuck-in-set perseveration, and 2 measures of intrusive errors yielded a 2 component solution with stuck-in-set perseverations and intrusive errors loading on Component 1, and recurrent perseverations loading on Component 2. Presence of a continuous perseveration on a graphomotor test was significantly associated with higher factor scores on Component 1, but not Component 2. The stuck-in-set perseveration and intrusion component was associated with the majority of the other neuropsychological tests administered, including tests of executive function and memory. The recurrent perseveration component was not associated with the other measures of cognitive functioning. Presence of a continuous perseveration was associated with executive function but not memory measures. This study provides evidence that recurrent perseverations are distinct from the other types of perseverative and intrusive errors, and that stuck-in-set and intrusive errors are good indicators of general cognitive functioning in patients with subcortical pathology. This research was supported in part by National Institute of Neurological Disorders and Stroke Grant R01 41372 to J.V.F.

Perseverative behaviour in fluent and non-fluent aphasic adults

Perseveration by type (recurrent, continuous, or stuck-in-set) was examined for 30 stroke patients, 20 of whom exhibited fluent aphasia, and 10 with non-fluent aphasia. Comparisons were made between the two aphasic subject groups on two verbal and two non-verbal tasks. Twenty-eight of the patients (93%) produced at least one instance of perseveration. The most commonly occurring type was recurrent perseveration. Instances of continuous perseveration also were common and were produced by 18 patients. Stuck-in-set perseveration was uncommon with only two patients exhibiting this form of perseveration. No differences were observed in the frequency of perseveration across the four tasks between fluent and non-fluent aphasic patients. Perseveration was significantly correlated with aphasia severity, but not with time post-onset.

Verbal perseveration of dementia patients

Patterns of perseveration and frequency of carrier phrases were studied in the verbal descriptive discourse of dementia patients controlled for etiology and severity. Dementia patients were found to perseverate significantly more frequently than normals and severity of dementia was more strongly associated than etiology with increased perseveration. Frequency of carrier phrases did not distinguish the descriptive discourse of dementia patients from normals. Discontinuous perseveration was more common than continuous perseveration, and perseveration of ideas after an intervening response was the perseverate most typical of the dementia patient. Findings of the study are related to prominent theories of the cause of perseveration.

Varieties of perseveration

We propose a new taxonomy for perseveration consisting of three categories which are distinctive at the levels of clinical features, process, and neuroanatomy. Stuck-in-set perseveration, the inappripriate maintenance of a current category or framework, involves an underlying process deficit in executive functioning and is related neuroanatomically to frontal lobe damage. Recurrent perseveration, the unintentional repetition of a previous response to a subsequent stimulus, involves an abnormal post-facilitation of memory traces and is related neuroanatomically to posterior left hemisphere damage. Continuous perseveration is the inappropriate prolongation or repetition of a behavior without interruption. It involves a deficit in motor output and is most common in patients with damage to the basal ganglia.

Perseveration in brain-injured adults

Despite the acceptance of perseveration as a characteristic sign of disturbed CNS functioning, objective data relative to its nature and occurrence are noticeably lacking. Data obtained in this study, not unexpectedly, indicate that perseverative responses occur more often in brain-injured than in normal subjects. The brain-injured subject most likely to evidence perseveration appeared to be one who (1) had suffered a CVA (2) less than 6 months ago that (3) resulted in aphasia. Two types of perseveration, repetitious and continuous, were noted in the responses of the brain-injured with higher incidences of the repetitious type occurring. It was felt that the behavioral definitions used to differentiate between repetitious and continuous perseveration allowed for reliable judgments between observers.