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Cris Zampieri

Publications and source records attributed to Cris Zampieri.

7 recordsLinked to original sources
PubMed2025

Similarities and Differences in the Late-Onset GM2 Gangliosidoses: Tay-Sachs and Sandhoff Diseases.

The two predominating subtypes of late-onset GM2 gangliosidosis are late-onset Tay-Sachs (LOTS) and late-onset Sandhoff disease (LOSD). Due to shared deficiencies of ß-hexosamindase A and significant clinical overlap, the two diseases have been considered indistinguishable. However, a growing body of evidence supports the notion of several distinctions between the two diseases. In this study, we highlight these distinctions through the cross-sectional evaluation of 27 late-onset GM2 gangliosidosis participants. Twenty-one participants with LOTS and 6 with LOSD were included in this study. We performed physical examinations alongside assessments for gait, balance, muscle strength, ataxia, nerve conduction velocities, and analyzed brain magnetic resonance imaging. Lower limb weakness (95% in LOTS, 100% in LOSD) and later development of upper limb weakness (90% in LOTS, 83% in LOSD) was highly prevalent in both cohorts. Accompanying gait disturbances, balance issues, and dysmetria (as assessed by the brief ataxia rating scale [BARS]) were also prevalent in both cohorts. Strength testing for the quadriceps and hamstrings demonstrated weakness in both cohorts, primarily impacting extensor muscles. Supratentorial gray and white matter volumes in both cohorts were similar to normative data. In contrast, BARS scores for dysarthria and oculomotor dysfunction were present and heterogenous in LOTS participants and absent in LOSD participants. 24% of LOTS participants and none of the LOSD participants had a history of neuropsychiatric symptoms. Cerebellar volume including lobules V and VI were lower in LOTS compared to LOSD and normative data. However, length dependent sensory neuropathy was present in all LOSD participants but absent in LOTS participants. Dysfunction of the posterior cerebellum (lobules VI, VII, and IX) has been shown to cause cerebellar cognitive affective syndrome (CCAS), that includes cognitive and behavioral disturbances. Furthermore, cerebellar dysfunction of lobules V and VI has been linked to dysarthric speech, and dysfunction of the posterior cerebellum has been linked to oculomotor symptoms. The finding of low cerebellar lobule volumes in LOTS, suggests the distinctive features of the LOTS phenotype are related to cerebellar dysfunction. However, the sensory symptoms unique to LOSD remains a mystery. The molecular and biochemical basis for the dichotomy between the LOTS and LOSD phenotypes requires further investigation.

GM2 Gangliosidosis↗
PubMed2006

Gaze-shift strategies during functional activity in progressive supranuclear palsy.

The relative sparing of visual fixation in parallel with disruption of saccade function in progressive supranuclear palsy (PSP) creates a unique human model for the study of gaze-shift strategies which are adopted when vertical gaze palsy impairs primarily the eye-movement component of gaze control. It was hypothesized that people with PSP would rely on head pitch as a primary component of gaze shift during a platform stepping task and that there would be a predominance of fixation behavior (counter rotation of the eyes during head pitch) while attempting a down-gaze shift. Fourteen subjects with probable and 5 subjects with possible PSP participated in two experiments to measure visual fixation and gaze shift on the same continuum (using a derived vertical gaze fixation score, vGFS). Experiment #1 required gaze fixation during passive head pitch at 0.1-0.2 Hz, whereas experiment #2 required gaze shifts during a continuous platform step on, over, and off task. The primary gaze-shift strategy involved pitching the head downward to compensate for a loss in vertical saccade function. This strategy produced head pitch velocity that leads vertical eye velocity on the order of 200-500 ms. Gaze shifts during platform stepping showed greater fixation suppression (e.g., lower vGFS) in both groups of PSP compared to the visual stabilization task, but some subjects showed "fixation intrusion" during attempted gaze shift. The amount of eye movement was relatively constant when corrected for orbit height, whereas the extent of head pitch varied in proportion to the task demands. The mechanism controlling gaze in PSP, therefore appears to modulate head pitch independently of eye movement, but the gaze strategy seems dependent upon the extent of gaze dysfunction. These findings support the view that the desired gaze signal is parsed into separate eye and head pathways upstream from the burst neurons.

Adaptation, Physiological↗
PubMed2006

Association between vestibuloocular reflex suppression during smooth movements of the head and attention deficit in progressive supranuclear palsy.

With head movement, suppression of vestibular inputs during visual exploration is necessary not only for reorienting gaze, but also to direct attention to new visual targets. People with progressive supranuclear palsy (PSP) have difficulty suppressing the vestibuloocular reflex (VOR) and it was hypothesized that the magnitude of VOR suppression deficit correlates with the degree of degradation of attention and visuospatial performance. We evaluated cognitive and visuomotor function in 8 subjects with PSP (4 men and 4 women; ages 59-83 years). Gaze control was studied by measuring the accuracy of eye-head coordination during passive vertical and horizontal head-on-trunk movements. Fixation was assessed when subjects viewed either an earth-fixed or head-fixed target. A gaze fixation score (GFS) was calculated to represent the amount of error between eye and head movement in each plane (eye-head root mean square error normalized to the range of head rotation). The vertical but not horizontal GFS during attempted suppression of the VOR was significantly related to attention (r = -0.70; P = 0.05) and visuospatial ability (r = -0.76; P = 0.03). These findings suggest that the ability to suppress the VOR during vertical smooth movements of the head is associated with the magnitude of cognitive deficit in PSP.

Aged↗
PubMed2003

Aging and saccade-stepping interactions in humans.

Saccade-stepping interactions were compared in older and young persons to determine if visual anchoring theory could be applied to stepping behavior in both groups. Subjects rapidly stepped onto a platform. In some trials, a translucent shield was used to prevent visual fixation. Both elderly and younger subjects initiated downward saccades prior to footlift, but saccade-step latency was significantly longer for the elderly. Regardless of age, working memory was not sufficient to guide stepping in the absence of visual fixation. The findings support visual anchoring theory by demonstrating that older and young persons generate anticipatory downward saccades which precede the stepping action. Changes in the latency of saccade-step coupling with aging were attributed to slowed processing of visual anchors for obstacle avoidance. The central nervous system appears to accommodate age-related processing delays by initiating the down saccade well in advance of platform footlift, independently from stepping velocity.

Adult↗
PubMed2003

Saccade-stepping interactions revise the motor plan for obstacle avoidance.

The authors used a stimulus-response compatibility paradigm to assess the effect of changing the estimated time to obstacle contact. A limb-selection cue was presented in different phases of gait to young (n = 5) and to older (n = 4) adults while they were moving toward a foam obstacle in the walking path. A downward saccade was initiated after the cue; the saccade typically occurred during the stance phase of the target limb (the foot cued to lead the step over the obstacle). The mean saccade-step latency after the cue was on the order of -500 ms in both young and elderly participants. On reaching the obstacle, both groups generated an upward saccade approximately -300 ms before target footlift in both groups. Saccades following the limb-selection cue appeared to direct the gaze toward footfall targets just beyond the obstacle, whereas saccades generated just before obstacle footlift moved the gaze to the forward-looking direction. The elderly had significantly longer saccade-trailing-footlift latencies and prolonged gaze-fixation times than did the younger adults. Transient disruptions in optical flow appeared to be necessary for successful obstacle-avoidance behavior when there was an unexpected change in the estimated time to obstacle contact.

Adult↗
PubMedDate not supplied

Influence of elderly executive cognitive function on attention in the lower visual field during step initiation.

BACKGROUND: There is a well-established relationship between poor executive cognitive abilities and elderly fall risk, but the precise mechanism underlying this relationship is unknown. Older persons frequently fall or trip on objects below eye level, and it was hypothesized that the pathological mechanism linking low executive function and fall risk is a selective impairment in the resolution of visual attention in the lower visual fields. OBJECTIVE: To determine if normally sighted older persons living in the community with deficits in executive cognitive abilities have a reduced resolution of visual attention in the lower visual fields compared to elderly and younger subjects with high executive abilities. METHODS: Eye and head angulations were monitored as subjects fixated on a point rear-projected at eye level at the end of a 3- meter walkway. Visual stimuli were briefly presented (<300 ms) in the peripheral visual field (with and without distractors) to directly cue the selection of the right or left foot to lead a step over a foam obstacle resting at the subject's feet. No saccades were allowed until the stimulus was extinguished, at which time a down-saccade-step sequence moved the foot over the obstacle. The resolution of visual attention (tested with gratings) and the influence of target eccentricity in the upper and lower visual fields were evaluated. The primary outcome measures were step error and obstacle contact rate, saccade occurrence after extinguished stimulus and the log of cue-saccade latency (limb-independent reaction time). RESULTS: All groups experienced greater stepping errors than expected by chance when stimuli were presented in the lower versus upper visual field and with increasing eccentricity. However, the obstacle contact rate was greater, cue-saccade latency was prolonged, and fewer down-saccades were generated in the elderly group with poor executive abilities compared to those with high executive function and younger subjects. CONCLUSIONS: Loss of visual attention in the lower visual fields was not unique to elderly subjects with poor executive function. However, slowed processing time and reduction in the frequency of down-saccades associated with a low level of executive function potentially account for the mechanism linking executive abilities and fall risk.

Accidental Falls↗