Biomedical subjects

L Pizzamiglio

Publications and source records attributed to L Pizzamiglio.

At least 37 records · Page 2Linked to original sources

PubMed1997

Dissociation between position sense and visual-spatial components of hemineglect through a specific rehabilitation treatment.

Current evidence suggests an association between contralesional extra-personal hemineglect, and deficits of arm position sense in patients with damage to the right cerebral hemisphere. A unitary deficit may produce both disorders, or this association may reflect the anatomical contiguity of relevant brain structures. A rehabilitation treatment, devised for visual-spatial hemineglect, was used to investigate these hypotheses in 8 patients with damage to the right cerebral hemisphere. The treatment improved hemineglect, but not the position sense deficit. The severity of the latter was however transiently reduced by optokinetic stimulation, with effects similar to those found in visual-spatial hemineglect. These effects of rehabilitation suggest that extra-personal hemineglect and the neglect-related component of the position sense disorder of the left forearm are independent, though frequently associated, deficits. Implications for the design of rehabilitation programs are discussed.

Aged↗

PubMed1997

Motor deficits and optokinetic stimulation in patients with left hemineglect.

Optokinetic stimulation with left direction of the movement of luminous dots temporarily improved motor weakness of the left hand in two right-brain-damaged patients with left spatial hemineglect. Stimulation to the right had no effect. In two left-brain-damaged patients, optokinetic stimulation did not affect the right motor weakness, regardless of direction of the movement of the optokinetic stimuli. We suggest that in patients with left hemineglect, contralesional motor deficits have a neglect-related component, which, as other aspects of the neglect syndrome, may be improved by optokinetic stimulation. The mechanisms may include a temporary restoration of the spatial coordinates of bodily representations, pathologically distorted towards the side of the lesion.

Aged↗

PubMed1996

Facilitatory effect of neglect rehabilitation on the recovery of left hemiplegic stroke patients: a cross-over study.

A study of the effect of specific training for visual neglect on the recovery of motor and functional impairment in stroke patients is reported. Two groups of right hemisphere stroke patients with hemispatial neglect and one group without neglect were assessed by means of three functional and neurological scales (Rivermead Mobility Index, Barthel Index, Canadian Neurological Scale). Three evaluations were made at 0, 2 and 4 months from the beginning of physical rehabilitation. During the first 2 months of physical rehabilitation one of the two groups of neglect patients was randomly assigned to specific training for neglect, and the second group to a general cognitive intervention; during the final 2 months of rehabilitation the types of training were switched in the two groups. The non-neglect patients improved steadily during physical rehabilitation. In contrast, the functional recovery of the two neglect groups was time-locked to the period of the specific training for neglect. At the time of admission, the two neglect groups performed at the same level; after 2 months of rehabilitation, the group with neglect training showed higher functional recovery than the group with only general cognitive intervention. When the latter group received neglect training, there was no longer any difference between the two neglect groups. This pattern was present for both of the functional scales used but not for the neurological scale. Motor and functional recovery of stroke patients with neglect seems to be significantly improved by the simultaneous presence of a treatment specifically focused on neglect.

Cerebrovascular Disorders↗

PubMed1996

Asymmetry of rapid eye movements in chronic unilateral neglect does not change with behavioral improvement induced by rehabilitation treatment.

A strong reduction of leftward rapid eye movements (REMs) during REM sleep was recently documented in patients with severe and chronic left unilateral neglect. The aim of the present research was to study the stability of the unilateral suppression of REMs before and after a rehabilitative treatment for neglect disorders. Six right-brain-damaged patients were tested for neglect at the beginning and at the end of a 2 month cognitive rehabilitation treatment. REMs were recorded during 1 night of undisturbed sleep before and after the training. Five out of 6 patients improved considerably their ability to attend the previously neglected left hemispace; in all patients REM asymmetry remained unchanged. The lack of relationship between the improvement of the neglect disorder and the persistence of REM asymmetry suggests that the sensorimotor mechanisms activated by rehabilitation are different from those involved in the production of REMs. It is proposed that: (a) the directional vectors of REMs are computed on the basis of the exclusive or predominant endogenous activation of the central attentional mechanisms related to vestibular input; (b) the presence of rightward and leftward saccades and the positive effects of the rehabilitation treatment are functionally linked to attentional oculomotor mechanisms that are not active in REM sleep.

Aged↗

PubMed1996

Beyond unilateral neglect.

When required to set the endpoints of an imaginary horizontal line of a given length on the basis of its midpoint printed on a sheet of paper, left neglect patients most frequently misplaced endpoints leftwards. Though giving rise to the very same disproportion usually found with these patients on canonical line bisection tasks, this behaviour cannot be accommodated by current explanations of unilateral neglect. When the task was executed during leftward optokinetic stimulation (OKS), a manoeuvre known temporarily to improve neglect symptoms, the disproportion increased instead of vanishing. We therefore suggest that unilateral neglect is a manifestation of a disorder primarily implying a horizontal anisometry of space representation and that manipulations such as OKS may remove neglect without normalizing the representational medium itself.

Adult↗

PubMed1996

Gender priming in Italian.

The goals of the present study were (1) to determine whether grammatical gender on a noun modifier can prime recognition of the following noun, (2) to determine whether the priming effect involves facilitation, inhibition, or both, and (3) to compare performance across three different tasks that vary in the degree to which explicit attention to gender is required, including word repetition, gender monitoring, and grammaticality judgment. Results showed a clear effect of gender priming, involving both facilitation and inhibition. Priming was observed whether or not the subjects' attention was directed to gender per se. Results suggest that gender priming involves a combination of controlled postlexical processing and automatic prelexical processing. Implications for different models of lexical access are discussed, with special reference to modular versus interactive-activation theories.

Adult↗

PubMed1995

Gravity and hemineglect.

Spatial cognition requires the integration of visual inputs with proprioceptive and vestibular information about the position of the eye, the head and the body. All these sources are used by the brain to produce multiple higher-order (e.g. egocentric) representations of space, subserving accurate spatial behaviour. Such spatial representations are disrupted by unilateral cerebral damage producing neglect in the contralateral side of space. In eight brain-damaged patients with left unilateral neglect the manipulation of gravitational-otolithic information, obtained by placing patients in a supine position, produced a significant reduction of the rightward directional error in the line bisection task in all cases. This finding suggests that, in patients with neglect, gravitational information is processed in a non-symmetrical fashion, with a rightward bias towards the side of the lesion. This is the first study showing that manipulation of gravitational input affects neuropsychological disorders of visuo-spatial processing.

Aged↗

PubMed1995

Amplitude and speed change of the optokinetic response in patients with and without neglect.

The present study quantitatively investigated the slow and quick phases of optokinetic nystagmus (OKN) in four groups of patients: right unilateral brain-damaged patients with neglect, left and right patients without neglect or hemianopia and patients with left or right retrogeniculate lesions and lateral homonymous hemianopia. Our results indicate that only neglect patients show a perturbation of both components of OKN. A comparison among MRI images of different patients shows that a region involving area 37 and adjacent areas 39 and 19, was impaired in all patients with neglect, but not in any other patient with either right or left lesions.

Adolescent↗

PubMed1995

Optokinetic stimulation affects both vertical and horizontal deficits of position sense in unilateral neglect.

The effects of optokinetic stimulation on the disorders of position sense in the horizontal and vertical planes were assessed in 24 patients with unilateral cerebral lesions (eight right brain-damaged patients with visuo-spatial hemineglect, eight right brain-damaged patients without neglect, eight left brain-damaged patients without neglect). In neglect patients, the position sense disorder was more severe, and affected by optokinetic stimulation in a direction-specific fashion. In both the horizontal and the vertical plane, and in both arms, stimulation with a direction of the movement contralateral to the side of the lesion improved the disorder, whereas stimulation with an ipsilateral direction worsened the deficit. The suggestion is made that in patients with neglect the disorder of position sense is produced, at least in part, by an ipsilateral distortion of an egocentric co-ordinate system, comprising both the horizontal and the vertical dimension, which may be affected by direction-specific optokinetic stimuli.

Aged↗

PubMed1995

Effectiveness of neglect rehabilitation in a randomized group study.

The effectiveness of neglect rehabilitation training has been studied in two randomly selected groups of right brain-damaged patients. All patients proved heminattentive on a standard battery 2 months or more after the CVA. One group received 2 months of treatment immediately after admission to a clinic, and the other group received only general cognitive stimulation for the same amount of time. At the end of this period a comparison showed significant improvement in the first group, based on a standard test battery and a functional scale. The second group was then given rehabilitation training for neglect for the same amount of time and obtained similar improvement. It is concluded that the rehabilitation program produces significant results, which generalize to situations similar to those of everyday life. The importance of the duration of training on the generalization of learning is briefly discussed with reference to previous negative reports in the literature.

Aged↗

PubMed1995

Gender and lexical access in Italian.

Two new procedures were employed to investigate the effects of semantic and grammatical gender on lexical access in Italian and to investigate the interaction of gender with other factors that are known to influence lexical access in other languages. The gender-monitoring task requires a conscious decision about the gender of each noun, whereas the word repetition task does not require explicit attention to gender. In both tasks, single words are presented out of context, under speeded conditions. Both procedures proved to be sensitive indices of word recognition, with reaction times that are closely tied to the point at which words can be uniquely identified (although some processing before and after the uniqueness point was seen). In both tasks, reaction times were strongly affected by phonological factors (e.g., length, number of syllables, and presence of frication on the initial consonant). Phonological transparency of gender marking had a reliable effect on gender monitoring but had no effect on word repetition, suggesting that explicit attention to gender may be a factor affecting utilization of this phonological cue. Semantic factors (including semantic gender) had no effect on performance. Frequency and age of acquisition had very small effects when other factors were controlled. Implications for current models of lexical access are discussed, with special reference to the role of gender.

Humans↗

PubMed1994

Right neglect following right hemisphere damage?

From a sample of 90 stroke cases showing visual inattention following right hemisphere brain damage, 17 cases were identified who showed more inattention on the right than the left side on some tests. Eight of these subjects had CT scan-confirmed unilateral right hemisphere damage and one of these eight had MRI scan-confirmed unilateral right brain damage. A number of hypotheses are examined to explain this "paradoxical" right inattention. The most parsimonious proposes that right inattention is produced by an interaction of a compensatory left sided scanning strategy in association with a non-lateralised attentional loss.

Adult↗

PubMed1993

Unilateral neglect restricted to visual imagery.

Disorders in perceiving and exploring the visual space contralateral to a brain lesion have been frequently described. Many patients with hemi-neglect for extrapersonal space also show neglect in a representational domain when the task requires imagining a well-known piazza from a given vantage point or comparing two visual images. Cognitive and psychophysiological studies show a functional parallelism between the perceptual and imaginative domain, indicating that spatial perception and imagery share the same neural substrata. Here we describe a patient with a persistent disorder in visual imagery for familiar piazzas in the absence of any neglect for stimuli located in a far or near space or on his own body. Contrary to previous cases involving imagery disorders, computerized tomography scans showed a lesion confined to the right frontal lobe, suggesting the role of the frontal lobe in some specific types of mental imagery.

Cerebrovascular Disorders↗

PubMed1993

Disturbances of the rapid eye movements (REMs) of REM sleep in patients with unilateral attentional neglect: clue for the understanding of the functional meaning of REMs.

Horizontal saccades during wakefulness and horizontal rapid eye movements (REMs) during REM sleep were recorded in 6 unilateral brain damaged patients suffering from attentional neglect and 6 unilateral brain damaged control patients. During REM sleep, patients with neglect showed a nearly total suppression of REMs directed away from the side of the lesion; controls had a significantly milder frequency reduction of the same movements. In all patients the frequency reduction of REMs contralateral to the lesion equally affected isolated REMs (i.e., REMs preceded by intervals of oculomotor quiescence longer than 2 sec) and REM bursts (i.e., REMs preceded by intervals shorter than 2 sec). During voluntary inspection in waking, saccades directed ipsilaterally and contralaterally to the lesion were present in both groups of patients, although patients with neglect confined their inspection to the hemispace ipsilateral to the lesion. Results are discussed in terms of their implications for the understanding of the neurophysiological basis of REM sleep oculomotor activity and dream production, as well as for the neurophysiopathological basis of the neglect syndrome. It is proposed that REMs are functionally equivalent to waking reflex orienting saccades generated by a neural network including the relevant modulatory action of the parietal lobes and the superior colliculi.

Aged↗

PubMed1993

Deficits of position sense, unilateral neglect and optokinetic stimulation.

The effects of optokinetic stimulation on position sense disorders were investigated in a series of 30 patients with unilateral vascular lesions (10 right brain-damaged patients with visuospatial hemineglect, 10 right brain-damaged patients without visuo-spatial hemineglect, 10 left brain-damaged patients), and 10 control subjects. The position sense deficit was more severe in right brain-damaged patients with neglect, where both the contralateral and the ipsilateral arm were involved. Optokinetic stimulation was effective only in right brain-damaged patients with neglect: stimulation with a leftward movement (contralateral to the side of the hemispheric lesion) improved the position sense deficit, while stimulation with a rightward (ipsilateral) movement produced a worsening of the performance level. These findings suggest that in right brain-damaged patients with neglect the position sense deficit has a nonsensory component, related to neglect, which may be affected by optokinetic stimulation. The role of the derangement of sensory and perceptual-egocentric representations of the body and of extrapersonal space in producing position sense disorders is discussed.

Aged↗

PubMed1993

Priming effect in a color discrimination task.

Two experiments were run to test whether the automatic coding of colors generates priming effects. Subjects were tachistoscopically presented a series of prime-target sequences. The prime stimulus could be either a red, green, or black circular dot, followed by a red or green annular ring (target). The role of automatic and conscious mechanisms was investigated in Exp. 1 by manipulating the predictive validity of the prime stimuli (80%, 50%, 20%), keeping constant the value of stimulus-onset asynchrony (350 msec.). Analysis showed priming effects even in the low predictive condition, where no conscious expectations could be activated. In Exp. 2, three different values of stimulus-onset asynchrony were used, 150, 350, and 2100 msec. Priming effects were obtained in the short and medium stimulus-onset asynchrony condition but not in the long one. Over-all, the data of both experiments produce converging evidence which indicates that the automatic elaboration of colored stimuli may produce priming effects.

Adult↗

PubMed1992

The role of frame size on vertical and horizontal observers in the rod-and-frame illusion.

The rod-and-frame illusion was used to examine a proposed distinction between the mechanism responsible for frame effects on rod-adjustment errors with large displays and the mechanism responsible for errors with small displays. It was suggested that visual-vestibular mechanisms are involved only when the rod is surrounded by a large tilted frame. Errors in the perceived vertical with small frame would instead be due to purely visual mechanisms. To examine this dual process model, we compared errors at small and large frame when the body was vertical or horizontal. There is evidence to suggest that tilting the body affects visual-vestibular interactions, but there is no reason to expect that body tilt would affect intravisual interactions. Hence, we hypothesized that body tilt would increase errors for large frame, but not for small frame. Eight subjects were tested in four different conditions, corresponding to the combination of two body orientations (vertical versus horizontal) and two frame sizes (47.5 versus 10.5 deg of visual angle). Fourier analysis of data was performed. Repeated measures ANOVA tested the hypothesis about frame size and body orientation. The hypothesis was not confirmed. More specifically, we found that tilting the body increased errors for the small frame as well as for the large frame. The interaction between frame size and body orientation was not significant. Results are discussed in relation to the proposed dual-process model.

Adult↗

PubMed1992

Cognitive rehabilitation of the hemineglect disorder in chronic patients with unilateral right brain damage.

Thirteen patients with a stabilized hemineglect symptomatology due to right-hemisphere lesions were subjected to a rehabilitation training specifically aimed at reducing the scanning deficit. The training consisted of four procedures (visual-spatial scanning, reading and copying training, copying of line drawings on a dot matrix, and figure description) which lasted 40 sessions. By the end of therapy, the patients as a group showed significant improvements on several standard tests of hemineglect. The results on a Semi-structured Scale for the Functional Evaluation of Hemineglect pointed to the extension of exploratory improvements to situations similar to those of daily life. In contrast, patients improved very slightly on a variety of standard visual-spatial tests, indicating the specificity of training in reducing the scanning defect. Seven patients were examined at a follow-up several months after the end of therapy and appeared stable on both standard and functional tests of neglect.

Aged↗