1,721,004 research outputs found
What kind of integration between qualitative and quantitative measures in spatial-deficit recovery? Neuropsychological evidence for the assessment and intervention
No full textQualitative and quantitative measures to explore the assessment procedures and the intervention strategies for the successive recovery of spatial attentional deficits (such as neglect syndrome) were recollected in the past years within neuropsychological domains. However, whereas the real impact of these two distinct methodologies on the patients’ recovery were largely considered, no specific analysis was conducted to directly compare the long-lasting effects of these methodologies taking into account some subjective and contextual main variables, as well as it was not considered the impact of the integration between the qualitative and quantitative perspective. Firstly, from one side the effective compliance of patients in clinical specific treatments was underestimated or unspecifically considered. From the other side the effective incidence of qualitative (such as psychometric and assessment measures) or the quantitative (such as experimental and behavioural measures) methodology within their ecological context (clinical structure/laboratory setting) was scarcely analyzed. Secondly, a main caveat of the present research domain on spatial deficit recovery was the absence of a systematic survey on the effective applicability of the two measure types in integration each other. Coherence, proficiency and improving of this integrative view, that may include both the clinical and experimental approach, is suggested and discussed at light of the recent introduction of new methodologies. Between the others, brain stimulation (induced mainly by transcranial magnetic stimulation, TMS, or direct current stimulation, tDCS) may offer a unique opportunity to directly observe the effect of a joined strategy of assessment and intervention (quali- and quanti-tative) for the health recovery of patient
Neuropsychological evaluation of visuo-spatial neglect. Is there a relation between quantitative and qualitative methods?
No full textVisuo-spatial neglect is one of the most frequent neuropsychological disorders after a brain damage. Clinical Neuropsychologists work everyday with persons with this specific
attentional syndrome either for assessment and rehabilitation. Scientific literature provides a wide amount of instruments in particular for neuropsychological evaluation and most of them are based upon quantitative methodology, that is they are aimed to provide numerical values in order to assess neglect in terms of impairment. On the other hand, very few instruments lead to an evaluation of neglect in terms of disability. In this work we want to provide a brief description of the most used tests arguing for a relation between quantitative methods, as assessment of impairment, and qualitative methods, as instruments for disability. Finally, we give some suggestions, on the base of our experience, to enforce qualitative methodology in neglect assessment
How to differentiate between neglect and hemianopia. Four experiments on healthy subjects
No full textOne of the most frequent difficulty in neuropsychological assessment is the differentiation between neglect and hemianopia. Since there is a wide agreement in implicit information processing for patients with neglect, we hypothesized that a priming word in the neglected field should determine a semantic activation effect even when it is not consciously perceived by the patient. On the contrary if the priming word occurs in a blind hemifield this should not determine any facilitation effect. As first step we tested a “locally-dependent” priming effect on healthy subjects in a semantic categorization task.
We conducted four experiments in which we modulated the presence of a string of “X” contralaterally to prime position, prime duration (150 vs 300 ms) and distance from monitor (50 cm vs 100 cm). Prime occurred in six different positions while target appeared in the center of the screen. Three different prime-target conditions were present: related, unrelated and neutral. Twenty healthy subjects took part to the first experiment (prime at 150 ms, 50 cm from monitor); 17 to the second (prime at 150 ms without contralateral string of X, 50 cm distance); 15 to the third (prime at 300 ms, 50 cm from monitor) and 17 to the fourth (prime at 300 ms, 100 cm from monitor).
Results: we obtained a significant main effect of semantic relation (p < .001) in all experiments but not in the first one. We then found a significant main effect of position (p < .05); in the fourth experiment (prime at 300 ms) this was significant for all the positions of the prime (p = .001). Moreover we observed that priming duration significantly affects subjects’ performance with slower RTs. No significances arose between the two distances from monitor. These first results confirmed significant semantic activation effect for different prime positions, specifically a higher prime duration seems to provide a more sensitive task to be used as differential between neglect and hemianopi
Top-down strategy in rehabilitation of spatial neglect: how about age effect?
No full textThe aim of this work is to verify the effectiveness of our treatment in patients with spatial neglect in relation to their age and to the severity of neglect. Lots of studies on rehabilitation were proposed and, in some of them, treatments based upon visual-scanning abilities were described. Our rehabilitation training is aimed to induce patients to find by themselves an adequate strategy to solve spatial problems and, after that, try to let this searching strategy as automatized as possible. In this study, forty-six patients with right brain damage and left visuo-spatial neglect underwent to this specific cognitive treatment. A neuropsychological battery was administered before and after treatment. Repeated measure MANOVA on test performances showed significant main effects of treatments, age, and severity of neglect; an interaction effect between these three variables was found as well. Our results confirm an effectiveness of treatment, in particular for elderly patients. Actually, they seem to show a better recovery of neglect after cerebral stroke, even for those of them affected by a severe neglect. These data could be explained in accordance with recent neurophysiological models that claim compensatory responses to reduce brain plasticity even in terms of reorganization of cognitive functions such as visuo-spatial attention
Bisection and visual exploration strategy in hemineglect: eye-movement measures for rehabilitation treatment
No full textAim of this study is to explore behavioral responses and eye movements of unilateral neglect patients in a virtual bisection task. Space to be bisected was included between two endpoint, segment length together with segment spatial dislocation were varied in order to test the presence of a “gradient effect” in both bisection behavior and visual exploration. Ten right neglect patients took part to the study, all data were then matched with those obtained from ten healthy participants. Behavioral measures (bisection and RTs) and eye-movements (fixation count and duration; first fixation count) were analyzed. Consistent spatial biases were found for bisection responses, RTs, fixation count and duration, as well as for the first fixation count. We then find a significant rightward bias in patients, i.e. increasing rightside bisection and rightward fixations when the stimuli were in the extreme left-position. Concerning merely segment length, we observed significant differences between-groups only for eye movement behavior, with increased rightward fixation count and duration in response to longer segments. In conclusion, “left-to-right” and “longer-to-shorter” continuous-gradient effects were not totally supported by our results, whereas an “extreme-left” gradient effect was suggested and discussed
Differentiate neglect and hemianopia with semantic priming paradigm. Evidences in three patients with acquired brain lesion
No full textBackground: A prime word in neglected visual field should determine semantic activation effect even when the patient does not consciously perceive it, while no activation effect should be expected if the prime occurs in a blind hemifield.
Objective: We aim to provide evidences on different information processing between neglect and hemianopia and find a task which could differentiate between them.
Methods: We enrolled three patients: two with left neglect; one with a bilateral lesion which determined left neglect and right homonymous hemianopia.
Task:Patients were required to press the space bar when a target word was deemed as “living entity”; each target was Firstly preceded by a prime word occurring in six possible positions on the horizontal line of the screen. Three different prime-target conditions were present: related, unrelated and neutral.
Results: We analyzed results as a multiple single case with a Crawford analysis:patientswithleftneglectshowed a significant activation effect in all portions of space (in average 60 ms quicker in “related condition”, p<.05), except when the prime occurred in the extreme left position. The patient with left neglect and right hemianopia showed semantic activation in the left neglected space (related condition, p<.001), but not in the right space (hemianopic field).
Conclusions: These results confirm the initial hypothesis: we found a semantic activation in the space affected by neglect but not in the hemianopic field; on these first data our task seems to allow a differentiation between the two deficits even though a test on a larger sample of patient is now in progress
Cognitive task to differentiate between visual field deficit and neglect
No full textNeglect patients are able to process visual stimuli even if they do not have an overt perception of them. Indeed, since first studies at the end of 80 s lot of works demonstrated the presence of an implicit information processing, specifically part of them focused on the presence of a semantic activation effect due to the onset of a prime (either word or picture) in neglected space. This kind of effect was not found in patient with visual field deficits. Actually hemianopia determines a variable reduction of visual field width and a consequent partial blindness for the patient. Even though there are different neuroanatomical substrates between neglect and hemianopia, we know that clinical examination (including neuropsychological assessment) may provide confounding results. Not so many studies tried to disentangle neglect from hemianopia even using an implicit information processing task to discriminate. In our previous works we hypothesized that a prime-word in the neglected field should determine a semantic activation effect differently for what expected by prime in hemianopic field. We discussed a single case patient with bilateral brain lesion causing both left neglect and right hemianopia. Our results confirmed a strong repetition priming effect only when prime occurred in neglect hemifield. In this work we will describe the performance of 8 patients with a unilateral brain lesion which causes the presence of left visual neglect or left homonymous hemianopia. The experimental procedure was identical to those one described in our previous work. The patients were required to press the space-bar when the target word belonged to a living category after a prime word onset on six different possible positions of the monitor. We collect data on a small group of patients but our first results have confirmed the hypothesis concerning semantic activation in the space affected by neglect but not in hemianopic field. This test gives than promising results as a tool for differential diagnosis, even if it requires minimal levels of attention to be executed
Can semantic priming paradigm differentiate between neglect and hemianopia? Experimental evidences from patients with acquired brain lesion
No full textBackground: One of the most frequent deals in nuero-rehabilitation field is the patient’s difficulty in exploring the surrounding space and neglect whatever encloses him. This phenomenon
could be caused by an attentional deficit (i.e. visuo-spatial neglect) or by a reduction of visual field width (hemianopia); most of the time, this exploration impairment could be determined by an interactive effect between these two causes. Even though there are different neuro-anatomical substrates between neglect and hemianopia, the performances of the patients may provide confounding results at the specific examinations.
In particular it is not yet clear if the observation at the neuropsychological tests is a unique
expression of neglect nor if the result at the visual-field exam is exclusively dependent by hemianopia. In the last twenty years only few studies tried to disantagle neglect from hemianopia. Besides these contributions, scientific literature provides lot of results concerning an effective implicit
processing of information for patients with neglect which is not present in patients with hemianopia. Since there is a wide agreement in an implicit information processing for patients with neglect, we hypothesize that a priming word in the neglected field should determine a semantic activation effect even when it is not consciously perceived by the patient; on the contrary if the priming word occurs in a blind hemifield should not determine any activation effect. In this work we
will describe the performance of three patients compaired to 15 healthy subjects in a semantic priming task.
Materials and methods: The experimental procedure consisted in a fixation point (+) which lasted in the center of the screen for 150 ms; after that a prime word occurred in six possible positions on the central horizontal line of the screen corresponding to three positions on the left and three on the right (from A=extreme left to F=extreme right). The prime lasted 300 ms and,
after 150 ms blanc, by the target word. Target words may belong to living or nonliving category. Subjects and patients were required to press the space-bar only when the target word belonged to a living category. Three different conditions were present: related (the same category for
prime and target), unrelated (different category for prime and target) and neutral (instead of a prime word, an “x” string appeared). Three patients took part to the experiment: two of them presented a right hemispheric lesion and left neglect; one a bilateral lesion which determines left neglect and right homonymous hemianopia.
Results: We analyzed data of healthy subject by means of a repeated measure ANOVA with two dependent variables: prime (related, unrelated, neutral) and position (A,B,C,D,E,F). The participants
showed shorter reaction times activation in the condition of semantic relation between prime and target (p<.05); moreover this semantic activation were present in all prime positions (p<.05). We compared the data of the patients with those one of healthy subjects by means of a Crawford analysis: the two patients with right brain lesion and left neglect showed a significant activation effect when in the “related condition” in all portions of space, except when the prime occurred in the extreme left position (named A). On the other hand the patient with left neglect and right hemianopia showed semantic activation in left portions (neglected space) but not in right space (hemianopic field).
Conclusions: We aimed to find a task that could be inserted in the differential diagnostic procedure for neglect and hemianopia. Our experimental results seem to show significant semantic priming effect in healthy partecipants: all of them showed lower RTs in case of relation between prime and target for every position in which prime occurred. In addition the data we obtained from patients confirmed our work hypothesis, that is we found a semantic activation in the space which is affected by neglect (failures to neuropsychological tasks) but not in hemianoptic field
Distinguish between visual neglect and hemianopia. A clinical study based on semantic priming effect
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Priming effect in patients with visual spatial neglect and hemianopia: a pilot study for the definition of a clinical trial
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