Biomedical subjects

R Grasso

Publications and source records attributed to R Grasso.

At least 19 recordsLinked to original sources

PubMed2003

Acid exposure and altered acid clearance in GERD patients treated for Helicobacter pylori infection.

BACKGROUND: After the eradication of Helicobacter pylori, an increased incidence of gastroesophageal reflux disease and acid gastric secretion have been reported. AIM: To evaluate the effect of Helicobacter pylori-eradication on proximal and distal gastroesophageal reflux and acid clearance in patients with gastroesophageal reflux disease. PATIENTS AND METHODS: Sixty-eight gastroesophageal reflux disease patients (age range 18-61 years) were studied by upper endoscopy. All underwent esophageal manometry and dual probe 24-h pH-metry. RESULTS: Percent of time at pH<4 was significantly increased in the proximal esophagus of Helicobacter pylori-eradicated patients compared to Helicobacter pylori-negative (2.4+/-0.5 vs. 1.0+/-0.2; p<0.01); no differences were found in the distal esophagus (14.0+/-3.7 vs. 9.0+/-1.4%, NS). The total number of reflux episodes was significantly higher in the proximal oesophagus of Helicobacter pylori-eradicated patients (37+/-3 vs. 22+/-3, p<0.05). In the distal esophagus, acid clearance was significantly longer, both during total time (1.4+/-0.2 vs. 0.8+/-0.7 min, p<0.01), and in the supine period (8.5+/-2.7 vs. 2.7+/-0.4 min, p<0.05). No differences were reported in the manometric parameters of the two groups of patients. CONCLUSION: In patients with gastroesophageal reflux disease, Helicobacter pylori eradication is associated with increased acid exposure of the proximal esophagus and delayed distal acid clearance.

Adolescent↗

PubMed2002

Allogeneic bone marrow transplantation (BMT) for adults with acute lymphoblastic leukemia (ALL): predictive role of minimal residual disease monitoring on relapse.

We developed a PCR-based method to monitor clonogenic IgH VDJ rearrangement as a possible predictor of relapse in patients with acute B-ALL after allogeneic bone marrow transplantation (BMT). We studied 23 patients at diagnosis, before and after BMT. At the time of BMT, 13 patients were in first complete remission, eight in second complete remission and two in relapse. Four patients were PCR negative before BMT and remained PCR negative also after BMT (-/- pattern). They are still in remission after a median follow-up of 41 months. Nineteen patients were MRD-positive before BMT: three were PCR negative at first determination after BMT (+/- pattern) and maintain remission. Sixteen patients were PCR-positive at first determination after BMT (+/+ pattern): five became PCR negative (+/+/- pattern) (four with chronic graft-versus-host disease (GVHD) and two after donor lymphocyte infusions (DLI)). Nine patients remained PCR-positive (+/+/+ pattern) (four remain in remission, and six relapsed); two patients died before transplant. In conclusion, PCR negative patients before BMT remained negative post-BMT; many pre-BMT positive patients had initial MRD positivity after BMT: 37% of them achieved a molecular remission with cGVHD or DLI.

Adolescent↗

PubMed2002

Control of foot trajectory in human locomotion: role of ground contact forces in simulated reduced gravity.

We studied the changes of vertical contact forces, lower limb kinematics, and electromyographic activity (EMG) at different speeds and gravitational loads. To this end healthy subjects were asked to walk on a motorized treadmill while the percentage of body weight unloaded (body weight support, BWS) was modified in steps by means of a well-characterized unloading system. BWS was set at 0, 35, 50, 75, 95, or 100% of body weight. Walking speed was 0.7, 1.1, 2, 3, or 5 km/h. We found that changing BWS between 0 and 95% resulted in drastic changes of kinetic parameters but in limited changes of the kinematic coordination. In particular, the peak vertical contact forces decreased proportionally to BWS; at 95%-BWS they were 20-fold smaller than at 0% and were applied at the forefoot only. Also, there were considerable changes of the amplitude of EMG activity of all tested lower limb muscles and a complex re-organization of the pattern of activity of thigh muscles. By contrast, the corresponding variation of the parameters that describe shape and variability of the foot path was very limited, always <30% of the corresponding values at 0 BWS. Moreover, the planar co-variation of the elevation angles was obeyed at all speed and BWS values. Minimum variance of limb trajectory occurred at 3 km/h. At 100% BWS, subjects stepped in the air, their feet oscillating back and forth just above but never contacting the treadmill. In this case, step-to-step variability of foot path was much greater than at all other BWS levels but was restored to lower values when minimal surrogate contact forces were provided during the "stance" phase. The results did not depend on the specific instruction given to the subject. Therefore we conclude that minimal contact forces are sufficient for accurate foot trajectory control.

Adult↗

PubMed2001

Baroreflex and oscillation of heart period at 0.1 Hz studied by alpha-blockade and cross-spectral analysis in healthy humans.

1. Parameters derived from frequency-domain analysis of heart period and blood pressure variability are gaining increasing importance in clinical practice. However, the underlying physiological mechanisms in human subjects are not fully understood. Here we address the question as to whether the low frequency variability (approximately 0.1 Hz) of the heart period may depend on a baroreflex-mediated response to blood pressure oscillations, induced by the alpha-sympathetic drive on the peripheral resistance. 2. Heart period (ECG), finger arterial pressure (Finapres) and respiratory airflow were recorded in eight healthy volunteers in the supine position with metronome respiration at 0.25 Hz. We inhibited the vascular response to the sympathetic vasomotor activity with a peripheral alpha-blocker (urapidil) and maintained mean blood pressure at control levels with angiotensin II. 3. We performed spectral and cross-spectral analysis of heart period (RR) and systolic pressure to quantify the power of low- and high-frequency oscillations, phase shift, coherence and transfer function gain. 4. In control conditions, spectral analysis yielded typical results. In the low-frequency range, cross-spectral analysis showed high coherence (> 0.5) and a negative phase shift (-65.1 +/- 18 deg) between RR and systolic pressure, which indicates a 1-2 s lag in heart period changes in relation to pressure. In the high-frequency region, the phase shift was close to zero, indicating simultaneous fluctuations of RR and systolic pressure. During urapidil + angiotensin II infusion the low-frequency oscillations of both blood pressure and heart period were abolished in five cases. In the remaining three cases they were substantially reduced and lost their typical cross-spectral characteristics. 5. We conclude that in supine rest conditions, the oscillation of RR at low frequency is almost entirely accounted for by a baroreflex mechanism, since it is not produced in the absence of a 0.1 Hz pressure oscillation. 6. The results provide physiological support for the use of non-invasive estimates of the closed-loop baroreflex gain from cross-spectral analysis of blood pressure and heart period variability in the 0.1 Hz range.

Adrenergic alpha-Antagonists↗

PubMed2001

Role of diaphragmatic crura and lower esophageal sphincter in gastroesophageal reflux disease: manometric and pH-metric study of small hiatal hernia.

The rapid pull-through (RPT) technique during esophageal manometry helps to identify various pressure profiles of hiatal hernia (HH), based on the presence of two high pressure zones: the diaphragmatic crura (DC) and the lower esophageal sphincter (LES). Our aim was to correlate different HH profiles with frequency of reflux episodes in patients with gastroesophageal reflux disease (GERD). Seventy-eight patients with GERD and HH underwent esophageal manometry with RPT and were grouped according to the prevalent pressure profile of HH. Twenty-four-hour pH-metry served to quantify traditional (TR) and nontraditional refluxes (drop of 1 pH unit with pH > 4 or pH < 4 and time < 5 sec) (NTR) during total, upright, and recumbent periods. The group with a prevalent "flat" HH profile, representing LES and DC impairment, had significantly more TRs in total time of reflux (P < 0.01) and in recumbent and upright periods (P < 0.05) compared to the group with a prevalence of the two pressure peaks, corresponding to LES and DC efficiency. However, the group with the flat profile had significantly more NTRs + TRs than the group with pressure peaks in total time (P < 0.01) and recumbent position (P < 0.001) but not in the upright position. Hiatal hernia predisposes to GERD, but only the associated impairment of the LES and diaphragmatic crura pressures represents a condition of high risk for gastroesophageal reflux events.

Diaphragm↗

PubMed2001

Functional dyspepsia symptoms, gastric emptying and satiety provocative test: analysis of relationships.

BACKGROUND: The correlation between symptoms and observed impaired function in functional dyspepsia is still inconsistent. The aims of the study were to obtain a measure of satiety by a meal test; to verify whether this compares with severity of symptoms assessed using a reproducible questionnaire; and to correlate the parameters of satiety test and gastric emptying with all the dyspeptic symptoms. METHODS: Fifty-two functional dyspepsia patients reported their symptoms on a standardized questionnaire that considered belching, bloating, early satiety, epigastric pain and burning, nausea, postprandial fullness and vomiting. They were monitored for gastric emptying of a solid caloric meal using a radionuclide technique and underwent a test to quantify meal-induced satiety by a liquid caloric meal. RESULTS: The number of kilocalories ingested during the satiety test until the occurrence of maximum satiety in healthy subjects was 110% higher than in the dyspeptic group (mean +/- s(mean): 1110 +/- 23 versus 532 +/- 56; P < 0.01). We found a significant positive correlation between gastric emptying rate and kcal of the satiety test (P < 0.01; r = 0.428). Logistic regression showed a significant inverse association between severity of early satiety-coded as absent, mild, moderate or severe, kcal of meal test (P = 0.01), and gastric emptying lag phase (P = 0.03). Bloating was associated directly with t(1/2) of gastric emptying (P = 0.03) and inversely with lag phase (P = 0.02). CONCLUSIONS: The satiety test gives a fine numerical measure of satiety and confirms the results of a symptoms questionnaire. Our study showed an indirect correlation between severity of early satiety--as measured by the satiety test, and gastric emptying rate, as well as an association between bloating and delayed gastric emptying.

Adult↗

PubMed2001

Detection of minimal residual disease in B-lymphoproliferative disorders: a three step SSCP-PCR method.

The most recent therapeutic approaches can improve the outcome of B-cell neoplasia. By PCR analysis we amplify tumor specific DNA sequences of clonal IgH rearrangement from a limited number of malignant cells against a background of normal B cells. Recently described PCR based techniques for tracking minimal residual disease (MRD) in B lymphoproliferative disorders have given promising but discordant results, with significant variations in the sensitivity and specificity of the procedures. We have developed a three step single strand conformational polymorphism polymerase chain reaction (SSCP-PCR) strategy which is able to detect clonal malignant cells in B lymphoproliferative disorders at a frequency as low as 1 in 10(6) cells. Since this method is simple, rapid, reliable and as specific as ASO-PCR, it could be especially useful in monitoring patients affected by B lymphoproliferative disorders in complete haematological and immunophenotypic remission.

B-Lymphocytes↗

PubMed2001

Molecular analysis of patients with relapsed or refractory intermediate-high grade non-Hodgkin's lymphoma with bone marrow infiltration undergoing peripheral blood progenitor cell transplantation.

BACKGROUND AND OBJECTIVES: IgH gene rearrangement studies with a polymerase chain reaction (PCR) technique can detect the persistence of clonal cells at molecular level during the remission phase. This persistence of clonal cells can be used to establish the relationship between minimal residual disease (MRD) and clinical outcome. We have developed a three-step single strand conformational polymorphism PCR strategy which is able to detect clonal B lymphoid cells at a frequency as low as 1 clonal cell in 10(6) normal cells. DESIGN AND METHODS: Twenty patients with intermediate or high-grade B non-Hodgkin's lymphoma (NHL) were evaluated. Patients were pre-treated with a median of two (range 1-4) conventional chemotherapy lines before high-dose cyclophosphamide (HDCY). All patients had their bone marrow (BM) involved by disease (median 10%; range 5-50%). Nineteen patients were offered high-dose therapy followed by peripheral blood progenitor cells (PBPC) autografting. RESULTS: MRD analysis was performed for each patient at the end of conventional chemotherapy and every three months after high dose therapy. All these patients achieved complete response (CR) after high dose therapy (HDT). Six patients relapsed after a median time of 24.5 months. All the studied apheresis samples were positive at the molecular analysis. All 6 patients still positive at the molecular analysis after PBPC autografting relapsed. The remaining 13 patients who were negative maintained CR. INTERPRETATION AND CONCLUSIONS: Whereas the detection of clonal cells in the apheresis samples did not predict an unfavorable outcome, the disappearance of the clonal rearranged band from the BM sample after HDT proved to be a favorable prognostic factor and was associated with long-lasting disease-free status

Adult↗

PubMed2001

Lymphoplasmacytic lymphoma/immunocytoma: towards a disease-targeted treatment?

Lymphoplasmacytic-lymphoplasmacytoid lymphoma (LPL)/Waldenstrom's macroglobulinemia (WM) or immunocytoma (IMC) consists of diffuse proliferation of small mature B lymphocytes, plasmacytoid lymphocytes, and plasma-cells. The nosographic definition includes the lack of histological, immunophenotypic, cytogenetic, and molecular markers considered specific of other types of lymphoma. The cells show surface Ig (usually IgM), B-cell-associated antigens and display the CD5-, CD23- and CD10- phenotype, which allows for differential diagnosis from B-CLL and mantle cell lymphoma. t(9;14)(p13;q32) chromosomal translocation has been found in 50% of all LPL cases. The cytogenetic rearrangement juxtaposes the PAX-5 gene, which encodes for an essential transcription factor for B-cell proliferation and differention, to the Ig heavy chain gene. The combination of chlorambucil and prednisone holds as the standard treatment and seems to guarantee good control of the disease in most patients. Similar therapeutic results have been described with the combination of cyclophosphamide, vincristine, prednisone with (CHOP) or without doxorubicin (CVP), or with a combination of other alkylating agents and prednisone. Nucleoside analogues, alone or in combination with alkylating agents and anthracyclines, provide good salvage therapy for IMC and being increasingly employed as first line therapy. In a multicentric European trial Foran et al. administered the chimeric anti-CD20-monoclonal antibody (Rituximab) to 28 patients with previously treated IMC. Seven out of 25 evaluable patients (28%) achieved a partial response. Byrd et al. examined the outcome of 7 previously treated WM patients who received weekly infusions of rituximab (375 mg/m2). Therapy was well tolerated by all patients, and there was no decrease in cellular immune function, or significant infectious morbidity. Partial responses were noted in three of these patients, including two with fludarabine-refractory disease. These data suggest that rituximab exerts clinical activity on heavily pre-treated patients with WM. Furthermore, Weide et al. first reported that WM-associated polyneuropathy can be treated effectively with a combination of chemotherapy and the anti-CD20 monoclonal antibody rituximab. Most published trials exploring the efficacy of high dose treatment as salvage therapy for relapsed or refractory low grade non Hodgkin's lymphoma have included prevalently follicular or lymphocytic lymphomas. In selected high risk patients radioimmunotherapy with autologous stem-cell rescue, and myeloablative therapy followed either by autologous stem cell transplantation (SCT) or allogeneic SCT might represent an alternative strategy.

Antibodies, Monoclonal↗

PubMed2000

Neck muscle vibration makes walking humans accelerate in the direction of gaze.

We studied the effect of the continuous vibration of symmetrical dorsal neck muscles in seven normal subjects during (a) quiet standing, (b) stepping in place movements and (c) walking on the treadmill. The experiments were performed in a darkened room and the subjects were given the instruction not to resist the applied perturbation. In one condition the velocity of the treadmill was controlled by feedback from the subject's current position. Head, trunk and leg motion were recorded at 100 Hz. In normal standing, neck vibration elicited a prominent forward body sway. During stepping in place, neck vibration produced an involuntary forward stepping at about 0.3 m s-1 without modifying the stepping frequency. If the head was turned horizontally 45 and 90 deg to the right or to the left, neck muscle vibration caused stepping approximately in the direction of the head naso-occipital axis. For lateral eye deviations, the direction of stepping was roughly aligned with gaze direction. In treadmill locomotion, neck vibration produced an involuntary step-like increase of walking speed (by 0.1-0.6 m s-1), independent of the initial walking speed. During backward locomotion, the walking speed tended to decrease during neck vibration. Thus, continuous neck vibration evokes changes in the postural reference during quiet standing and in the walking speed during locomotion. The results suggest that the proprioceptive input from the neck is integrated in the control of human posture and locomotion and is processed in the context of a viewer-centred reference frame.

Acceleration↗

PubMed2000

Spatial, not temporal cues drive predictive orienting movements during navigation: a virtual reality study.

A fundamental property of the human brain is the ability to make predictions of future sensory and motor events. We have recently found that steering manoeuvres when walking along curvilinear trajectories are controlled by an anticipatory guidance of the direction of head (and eyes). However it is unclear whether a time-related or space-related signal triggers such anticipatory head orienting movements. By simulating navigation along a multi-legged virtual corridor we show that anticipatory orienting movements are triggered (in standing subjects) by reaching specific locations rather than by the time to the approaching corridor's bend. Similar to what happens in car driving, specific spatial features of the route rather than time to collision seem to drive steering.

Adult↗

PubMed2000

Interactions between posture and locomotion: motor patterns in humans walking with bent posture versus erect posture.

Human erect locomotion is unique among living primates. Evolution selected specific biomechanical features that make human locomotion mechanically efficient. These features are matched by the motor patterns generated in the CNS. What happens when humans walk with bent postures? Are normal motor patterns of erect locomotion maintained or completely reorganized? Five healthy volunteers walked straight and forward at different speeds in three different postures (regular, knee-flexed, and knee- and trunk-flexed) while their motion, ground reaction forces, and electromyographic (EMG) activity were recorded. The three postures imply large differences in the position of the center of body mass relative to the body segments. The elevation angles of the trunk, pelvis, and lower limb segments relative to the vertical in the sagittal plane, the ground reaction forces and the rectified EMGs were analyzed over the gait cycle. The waveforms of the elevation angles along the gait cycle remained essentially unchanged irrespective of the adopted postures. The first two harmonics of these kinematic waveforms explain >95% of their variance. The phase shift but not the amplitude ratio between the first harmonic of the elevation angle waveforms of adjacent pairs was affected systematically by changes in posture. Thigh, shank, and foot angles covaried close to a plane in all conditions, but the plane orientation was systematically different in bent versus erect locomotion. This was explained by the changes in the temporal coupling among the three segments. For walking speeds >1 m s(-1), the plane orientation of bent locomotion indicates a much lower mechanical efficiency relative to erect locomotion. Ground reaction forces differed prominently in bent versus erect posture displaying characteristics intermediate between those typical of walking and those of running. Mean EMG activity was greater in bent postures for all recorded muscles independent of the functional role. The waveforms of the muscle activities and muscle synergies also were affected by the adopted posture. We conclude that maintaining bent postures does not interfere either with the generation of segmental kinematic waveforms or with the planar constraint of intersegmental covariation. These characteristics are maintained at the expense of adjustments in kinetic parameters, muscle synergies and the temporal coupling among the oscillating body segments. We argue that an integrated control of gait and posture is made possible because these two motor functions share some common principles of spatial organization.

Adult↗

PubMed2000

Influence of leg muscle vibration on human walking.

We studied the effect of vibratory stimulation of different leg muscles [bilateral quadriceps (Q), hamstring (HS) muscles, triceps surae (TS), and tibialis anterior (TA)] in seven normal subjects during 1) quiet standing, 2) stepping in place movements, and 3) walking on the treadmill. The experiments were performed in a dimly illuminated room, and the subjects were given the instruction not to resist the applied perturbation. In one condition the velocity of the treadmill was controlled by a feedback from the subject's current position. In normal standing, TA vibration elicited a prominent forward body tilt, whereas HS and TS vibration elicited backward trunk or whole body inclination, respectively. Q vibration had little effect. During stepping in place, continuous HS vibration produced an involuntary forward stepping at about 0.3 m s(-1) without modifying the stepping frequency. When the subjects (with eyes closed) kept a hand contact with an external still object, they did not move forward but perceived an illusory forward leg flexion relative to the trunk. Q, TS, and TA vibration did not cause any systematic body translation nor illusory changes in body configuration. In treadmill locomotion, HS vibration produced an involuntary steplike increase of walking speed (by 0.1-0.6 m.s(-1)). Continuous vibration elicited larger speed increments than phasic stimulation during swing or stance phase. For phasic stimulation, HS vibration tended to be more effective when applied during swing than during stance phase. Q, TA, and TS vibration had little if any effect. Vibration of thigh muscles altered the walking speed depending on the direction of progression. During backward locomotion, the walking speed tended to decrease after HS vibration, whereas it significantly increased after Q vibration. Thus the influence of leg muscle vibration on stepping in place and locomotion differed significantly from that on normal posture. We suggest that the proprioceptive input from thigh muscles may convey information about the velocity of the foot movement relative to the trunk.

Adult↗

PubMed1999

Time course of gaze influences on postural responses to neck proprioceptive and galvanic vestibular stimulation in humans.

We have previously shown that postural responses to vibration of neck dorsal muscles (NS) and to galvanic stimulation of the vestibular system (GS) are influenced by the direction of gaze. Here, we describe the time course of this effect. We found that eye orienting movements during NS induce shifts of body inclination toward the direction of gaze with a latency of about 2 s: the time course is smooth and a steady state is attained after about 5 s from eye movements. If eye eccentricity is maintained and NS or GS are sequentially repeated for as long as 2 min, the direction of sway drifts in the direction opposite to eye deviation. The findings reveal that the frames of reference for the control of posture may have a dynamic nature.

Adult↗

PubMed1999

Effect of gaze on postural responses to neck proprioceptive and vestibular stimulation in humans.

1. We studied the effect of gaze orientation on postural responses evoked by vibration of neck dorsal muscles or by galvanic stimulation of the vestibular system during quiet standing in healthy humans. Various gaze orientations were obtained by different combinations of horizontal head-on-feet (-90, -45, 0, 45, 90 deg) and eye-in-orbit (-30, 0, 30 deg) positions. The instantaneous centre of foot pressure was recorded with a force platform. 2. With a symmetrical position of the vibrator relative to the spine, neck muscle vibration elicited a body sway in the direction of the head naso-occipital axis when the eyes were aligned with it. The same result was obtained both during head rotations and when the head and trunk were rotated together. 3. For lateral eye deviations, the direction of the body sway was aligned with gaze orientation. The effect of gaze was present both with eyes open and eyes closed. After long-lasting (1 min) lateral fixation of the target the effect of gaze decreased significantly. 4. Postural responses to galvanic vestibular stimulation tended to occur orthogonal to the head naso-occipital axis (towards the anodal ear) but in eight of the 11 subjects the responses were also biased by the direction of gaze. 5. The prominent effect of gaze in reorienting automatic postural reactions indicates that both neck proprioceptive and vestibular stimuli are processed in the context of visual control of posture. The results point out the importance of a viewer-centred frame of reference for processing multisensory information.

Adult↗

PubMed1999

Replication of passive whole-body linear displacements from inertial cues. Facts and mechanisms.

Using path integration, normal subjects should be able to compute the distance of a traveled path even from the sole inertial sensory input. Blindfolded subjects were submitted to a passive linear forward displacement along 2 to 10 m. Their task was to replicate the traveled distance, still blindfolded, by driving the vehicle they were seated upon using a joystick that controlled linear speed. Subjects replicated both the length and the velocity profile of the passive travel, suggesting that a dynamic record of experienced motion is stored in memory. Even when the replication of passive motion dynamics was made impossible, the subjects could still replicate the displacement. The results are explained by a dynamic feedback model that performs a running comparison between the perceived instantaneous displacement of the ongoing motion and the displacement derived from a spatiotemporal record of perceived passive motion. A multimodal acceleration-related sensory input is transformed into a displacement-related perception through double time-integration.

Adult↗

PubMed1999

Basal ganglia and gait control: apomorphine administration and internal pallidum stimulation in Parkinson's disease.

Gait coordination was analyzed (four-camera 100 Hz ELITE system) in two groups of idiopathic Parkinson disease (PD) patients. Five patients underwent continuous infusion of apomorphine and were recorded in two different sessions (APO OFF and APO ON) in the same day. Three patients with a previous chronic electrode implantation in both internal globi pallidi (GPi) were recorded in the same experimental session with the electrodes on and off (STIM ON and STIM OFF). The orientation of both the trunk and the lower-limb segments was described with respect to the vertical in the sagittal plane. Lower-limb inter-segmental coordination was evaluated by analyzing the co-variation between thigh, shank, and foot elevation angles by means of orthogonal planar regression. At least 30 gait cycles per experimental condition were processed. We found that the trunk was bent forward in STIM OFF, whereas it was better aligned with the vertical in STIM ON in both PD groups. The legs never fully extended during the gait cycle in STIM OFF, whereas they extended before heel strike in STIM ON. The multisegmental coordination of the lower limb changed almost in parallel with the changes in trunk orientation. In STIM OFF, both the shape and the spatial orientation of the planar gait loops (thigh angle vs. shank angle vs. foot angle) differed from those of physiological locomotion, whereas in STIM ON the gait loop tended to resume features closer to the control. Switching the electrodes on and off in patients with GPi electrodes resulted in quasi-parallel changes of the trunk inclination and of the planar gait loop. The bulk of the data suggest that the basal-ganglia circuitry may be relevant in locomotion by providing an appropriate spatio-temporal framework for the control of posture and movement in a gravity-based body-centered frame of reference. Pallido-thalamic and/or pallido-mesencephalic pathways may influence the timing of the inter-segmental coordination for gait.

Aged↗

PubMed1999

Non-specific directional adaptation to asymmetrical visual-vestibular stimulation.

Subjective estimates of passive whole-body rotations in darkness were evaluated before and after exposure to asymmetrical incoherent visual-vestibular stimulation (VVS). Two subjects who showed large capacity for adaptation to symmetrical incoherent VVS were enrolled in the study. Strikingly, after 45 min of asymmetrical left-right VVS, perception of rotation decreased equally for rotations to the right and to the left indicating that the calibration of vestibular sensory input for spatial orientation did not undergo a directional specific control.

Acoustic Stimulation↗