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Georg Kerkhoff - One of the best experts on this subject based on the ideXlab platform.
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Journal of Neuropsychology (2014) © 2014 The British Psychological Society
2016Co-Authors: Marco Pitteri, Konstantinos Priftis, Francesca Meneghello, Ingo Keller, Georg Kerkhoff, Clinical Neuropsychology Unit, Outpatient ServiceAbstract:www.wileyonlinelibrary.com Extra-powerful on the visuo-perceptual space, but variable on the number space: Different effects of Optokinetic Stimulation in neglect patient
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extra powerful on the visuo perceptual space but variable on the number space different effects of Optokinetic Stimulation in neglect patients
Journal of Neuropsychology, 2015Co-Authors: Marco Pitteri, Francesca Meneghello, Ingo Keller, Georg Kerkhoff, Konstantinos PriftisAbstract:We studied the effects of Optokinetic Stimulation (OKS; leftward, rightward, control) on the visuo-perceptual and number space, in the same sample, during line bisection and mental number interval bisection tasks. To this end, we tested six patients with right-hemisphere damage and neglect, six patients with right-hemisphere damage but without neglect, and six neurologically healthy participants. In patients with neglect, we found a strong effect of leftward OKS on line bisection, but not on mental number interval bisection. We suggest that OKS influences the number space only under specific conditions.
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recovery from auditory and visual neglect after Optokinetic Stimulation with pursuit eye movements transient modulation and enduring treatment effects
Neuropsychologia, 2012Co-Authors: Georg Kerkhoff, Ingo Keller, C Marquardt, Stefan Reinhart, Frank Artinger, Helmut Hildebrandt, Wolfram ZieglerAbstract:Optokinetic Stimulation (OKS) modulates many facets of the neglect syndrome. This sensory Stimulation technique is known to activate multiple brain regions (temporo-parietal cortex, basal ganglia, brain stem, cerebellum) some of which are involved in auditory and visual space coding. Here, we evaluated whether OKS modulates auditory neglect transiently and induces a sustained effect (Study 1), and whether repetitive OKS permanently recovers auditory neglect (Study 2). In Study 1, 20 patients with visuospatial neglect and auditory neglect in an auditory midline task following rightsided stroke were randomly allocated to an experimental and a control group matched for neglect severity and socio-demographic factors. Both groups showed a stable, pathological shift of their auditory subjective median plane (ASMP) in front space to the right side. During leftward OKS the experimental group showed a complete normalization of the shift of the ASMP, which endured until 30 min postStimulation, and returned almost to baseline values 24h after OKS. In contrast, the control group who viewed the identical but static dot pattern, showed neither change in their ASMP during this condition, nor any significant change at 30 min or 24h postStimulation. In Study 2, we show in two samples of neglect patients (N = 3 each) that repetitive leftward OKS with smooth pursuit eye movements as a therapy induces lasting improvements in auditory (the ASMP) and visual neglect while visual scanning therapy yielded no measurable effects on auditory and significantly smaller effects on visual neglect. In conclusion, the experiments show that a single session of OKS induces rapid though transient recovery from auditory neglect including a sustained effect after termination of Stimulation, while repetitive OKS therapy yields enduring and multimodal recovery from auditory and visual neglect. OKS therapy with pursuit eye movements therefore represents a multimodally effective and easily applicable technique for the treatment of auditory and visual neglect.
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Optokinetic Stimulation affects word omissions but not stimulus centered reading errors in paragraph reading in neglect dyslexia
Neuropsychologia, 2011Co-Authors: Stefan Reinhart, Igor Schindler, Georg KerkhoffAbstract:Patients with right hemisphere lesions often omit or misread words on the left side of a text or the initial letters of single words, a phenomenon termed neglect dyslexia (ND). Omissions of words on the contralesional side of the page are considered as egocentric or space-based errors, whereas misread words can be viewed as a type of stimulus-centered error where the left part of a single perceptual entity (the word) is neglected. Previous patient studies have shown that Optokinetic Stimulation (OKS) significantly modulates many facets of the neglect syndrome, including the subjective body midline, line bisection and size distortions. An open question is whether OKS can also influence omissions and stimulus-centered errors in paragraph reading in ND. The current study compared the influence of OKS on both types of reading errors using controlled indented paragraph reading tests in a group of 9 right-hemisphere lesioned patients with ND, 7 patients without ND and 9 matched healthy controls. Leftward OKS significantly reduced omissions on the left side of the text in ND. In contrast, the pattern of stimulus-centered reading errors remained unchanged. In conclusion egocentric manipulations like OKS only appear to influence space-based attentional processes evident as omissions in paragraph reading but have no impact on stimulus-centered attentional processes evident as word-based errors during paragraph reading in ND.
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repetitive Optokinetic Stimulation induces lasting recovery from visual neglect
Restorative Neurology and Neuroscience, 2006Co-Authors: Georg Kerkhoff, Ingo Keller, V Ritter, C MarquardtAbstract:Purpose: To evaluate whether repetitive Optokinetic Stimulation with active pursuit eye movements leads to substantial and greater recovery from visual neglect as compared to conventional visual scanning training. Methods: Two groups of five patients with leftsided hemineglect were consecutively collected and matched for clinical and demographic variables as well as neglect severity. One group received five treatment sessions of repetitive Optokinetic Stimulation (R-OKS) within one week, while the other group received the same amount of conventional visual scanning training (VST) using identical visual stimuli and setup. All patients were treated in a single-subject baseline design with treatment-free intervals before (14 days) and after specific neglect therapy (14 days). Dependent variables were the improvements in digit cancellation, visuoperceptual and visuomotor line bisection and visual size distortion during treatment. The transfer of treatment effects was assessed by a paragraph reading test. Results: The results showed superior effects of OKS treatment in all five patients which generalized across all tasks administered and remained stable at follow-up. In contrast, no significant improvements were obtained after VST training in any of these tasks, except in line bisection. Conclusion: We conclude that the presentation of moving visual stimulus displays with active smooth pursuit eye movements can be more efficient than conventional visual scanning training using static visual displays.
Neal H Barmack - One of the best experts on this subject based on the ideXlab platform.
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activity dependent expression of acyl coenzyme a binding protein in retinal muller glial cells evoked by Optokinetic Stimulation
The Journal of Neuroscience, 2004Co-Authors: Neal H Barmack, Zuyuan Qian, Timothy R Bilderback, Henry Liu, Vadim YakhnitsaAbstract:Long-term horizontal Optokinetic Stimulation (HOKS) decreases the gain of the horizontal Optokinetic reflex and evokes the second phase of Optokinetic afternystagmus (OKAN-II). We investigated the possible molecular constituents of this adaptation. We used a differential display reverse transcriptase-PCR screen for mRNAs isolated from retinas of rabbits that received HOKS. In each rabbit, we compared mRNAs from the retina stimulated in the posterior-->anterior (preferred) direction with mRNAs from the retina stimulated in the anterior-->posterior (null) direction. Acyl-CoA-binding protein (ACBP) mRNA was one of four mRNAs selected by this screen, the proteins of which interact with GABA receptors. HOKS in the preferred direction increased ACBP mRNA transcription and ACBP protein expression. ACBP was localized to Muller glial cells by hybridization histochemistry and by immunohistochemistry. ACBP interacts with the alpha1-subunit of the GABA(A) receptor, as determined by a yeast two-hybrid technique. This interaction was confirmed by coimmunoprecipitation of ACBP and the alpha1-subunit of the GABA(A) receptor using an antibody to GABA(A)alpha1. The interaction was also confirmed by a "pull-down" assay in which histidine-tagged ACBP was used to pull down the GABA(A)alpha1. ACBP does not cross the blood-brain barrier. However, smaller truncated proteolytic fragments of ACBP do, increasing the excitability of central cortical neurons. Muller cells may secrete ACBP in the inner plexiform layer, thereby decreasing the sensitivity of GABA(A) receptors expressed on the surface of ganglion cell dendrites. Because retinal directional sensitivity is linked to GABAergic transmission, HOKS-induced expression of ACBP could provide a molecular basis for adaptation to HOKS and for the genesis of OKAN-II.
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activity dependent expression of calbindin in rabbit floccular purkinje cells modulated by Optokinetic Stimulation
Neuroscience, 2002Co-Authors: Neal H Barmack, Zuyuan QianAbstract:Optokinetic Stimulation activates visual climbing fiber pathways that synapse upon contralateral floccular Purkinje cells. Long-term horizontal Optokinetic Stimulation causes a progressive decrease in gain of the Optokinetic reflex and leads to the subsequent genesis of a prolonged negative Optokinetic afternystagmus. Since the flocculus is involved in adaptation to Optokinetic Stimulation, we used the technique of differential display reverse transcription-polymerase chain reaction to explore transcriptional changes in the flocculus evoked by long-term Optokinetically evoked climbing fiber discharge. Several differentially transcribed gene products were isolated and sequenced. One of these, calbindin mRNA, was expressed in relatively decreased abundance in the flocculus that received increased climbing fiber input. Decreased transcription of calbindin mRNA was confirmed by northern blots. Hybridization histochemistry was used to localize calbindin mRNA to Purkinje cells and confirmed decreased transcription of calbindin mRNA in Purkinje cells located in folium 1 of the flocculus. Western blots and immunohistochemistry localized the climbing fiber-evoked decreased expression of calbindin to Purkinje cells in folia 1 of the flocculus. The expression of four other calcium-binding proteins in the flocculus was not influenced by Optokinetic Stimulation. Changes in expression of calbindin could be evoked by decreases in intracellular calcium associated with climbing fiber-evoked decreases in Purkinje cell simple spike activity.The application of differential display reverse transcription-polymerase chain reaction has provided a positive screen for several molecules in addition to calbindin whose expression is affected by naturally evoked activity in a major synaptic pathway to the cerebellum. Further experiments will be required to specify the functional role of each of these molecules.
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cerebellar nodulectomy impairs spatial memory of vestibular and Optokinetic Stimulation in rabbits
Journal of Neurophysiology, 2002Co-Authors: Neal H Barmack, P Errico, A Ferraresi, H Fushiki, Vito Enrico Pettorossi, V YakhnitsaAbstract:Natural vestibular and Optokinetic Stimulation were used to investigate the possible role of the cerebellar nodulus in the regulation and modification of reflexive eye movements in rabbits. The nod...
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Optokinetic and vestibular Stimulation determines the spatial orientation of negative Optokinetic afternystagmus in the rabbit
The Journal of Neuroscience, 1999Co-Authors: Vito Enrico Pettorossi, Pierangelo Errico, Aldo Ferraresi, Neal H BarmackAbstract:Prolonged binocular Optokinetic Stimulation (OKS) in the rabbit induces a high-velocity negative Optokinetic afternystagmus (OKAN II) that persists for several hours. We have taken advantage of this uniform nystagmus to study how changes in static head orientation in the pitch plane might influence the orientation of the nystagmus. After horizontal OKS, the rotation axis of the OKAN II remained almost constant in space as it was kept aligned with the gravity vector when the head was pitched by as much as 80° up and 35° down. Moreover, during reorientation, slow-phase eye velocity decreased according to the head pitch angle. Thereafter, we analyzed the space orientation of OKAN II after Optokinetic Stimulation during which the head and/or the OKS were pitched upward and downward. The rotation axis of OKAN II did not remain aligned with an earth vertical axis nor a head vertical axis, but it tended to be aligned with that of the OKS respace. The slow-phase eye velocity of OKAN II was also affected by the head pitch angle during OKS, because maximal OKAN II velocity occurred at the same head pitch angle as that during Optokinetic Stimulation. We suggest that OKAN II is coded in gravity-centered rather than in head-centered coordinates, but that this coordinate system may be influenced by Optokinetic and vestibular Stimulation. Moreover, the velocity attenuation of OKAN II seems to depend on the mismatch between the space-centered nystagmus rotation axis orientation and that of the “remembered” head-centered Optokinetic pathway activated by OKS.
Jonathan C Horton - One of the best experts on this subject based on the ideXlab platform.
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vertical Optokinetic Stimulation induces diagonal eye movements in patients with idiopathic infantile nystagmus
Investigative Ophthalmology & Visual Science, 2020Co-Authors: John R Economides, Young Woo Suh, Joshua B Simmons, Daniel L Adams, Jonathan C HortonAbstract:Author(s): Economides, John R; Suh, Young-Woo; Simmons, Joshua B; Adams, Daniel L; Horton, Jonathan C | Abstract: Purpose:In patients with early ocular misalignment and nystagmus, vertical Optokinetic Stimulation reportedly increases the horizontal component of the nystagmus present during fixation, resulting in diagonal eye movements. We tested patients with infantile nystagmus syndrome but normal ocular alignment to determine if this crosstalk depends on strabismus. Methods:Eye movements were recorded in seven patients with infantile nystagmus. All but one patient had normal ocular alignment with high-grade stereopsis. Nystagmus during interleaved trials of right, left, up, and down Optokinetic Stimulation was compared with waveforms recorded during fixation. Six patients with strabismus but no nystagmus were also tested. Results:In infantile nystagmus syndrome, horizontal motion evoked a mostly jerk nystagmus with virtually no vertical component. A vertical Optokinetic pattern produced nystagmus with a diagonal trajectory. It was not simply a combination of a vertical component from Optokinetic Stimulation and a horizontal component from the subject's congenital nystagmus, rather in six of seven patients, the slow-phase velocity of the horizontal component during vertical Optokinetic Stimulation differed from that recorded during fixation. In the six strabismus patients without nystagmus, responses to vertical Optokinetic Stimulation were normal. Conclusions:In patients with congenital motor nystagmus, a vertical noise pattern drives a diagonal nystagmus. This appears to arise because of crosstalk between the vertical and horizontal components of the Optokinetic system. This abnormal response to vertical Stimulation is not caused by strabismus because it occurs in patients with infantile nystagmus without strabismus. Moreover, it is absent in patients with strabismus and no spontaneous nystagmus.
Ingo Keller - One of the best experts on this subject based on the ideXlab platform.
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Journal of Neuropsychology (2014) © 2014 The British Psychological Society
2016Co-Authors: Marco Pitteri, Konstantinos Priftis, Francesca Meneghello, Ingo Keller, Georg Kerkhoff, Clinical Neuropsychology Unit, Outpatient ServiceAbstract:www.wileyonlinelibrary.com Extra-powerful on the visuo-perceptual space, but variable on the number space: Different effects of Optokinetic Stimulation in neglect patient
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extra powerful on the visuo perceptual space but variable on the number space different effects of Optokinetic Stimulation in neglect patients
Journal of Neuropsychology, 2015Co-Authors: Marco Pitteri, Francesca Meneghello, Ingo Keller, Georg Kerkhoff, Konstantinos PriftisAbstract:We studied the effects of Optokinetic Stimulation (OKS; leftward, rightward, control) on the visuo-perceptual and number space, in the same sample, during line bisection and mental number interval bisection tasks. To this end, we tested six patients with right-hemisphere damage and neglect, six patients with right-hemisphere damage but without neglect, and six neurologically healthy participants. In patients with neglect, we found a strong effect of leftward OKS on line bisection, but not on mental number interval bisection. We suggest that OKS influences the number space only under specific conditions.
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recovery from auditory and visual neglect after Optokinetic Stimulation with pursuit eye movements transient modulation and enduring treatment effects
Neuropsychologia, 2012Co-Authors: Georg Kerkhoff, Ingo Keller, C Marquardt, Stefan Reinhart, Frank Artinger, Helmut Hildebrandt, Wolfram ZieglerAbstract:Optokinetic Stimulation (OKS) modulates many facets of the neglect syndrome. This sensory Stimulation technique is known to activate multiple brain regions (temporo-parietal cortex, basal ganglia, brain stem, cerebellum) some of which are involved in auditory and visual space coding. Here, we evaluated whether OKS modulates auditory neglect transiently and induces a sustained effect (Study 1), and whether repetitive OKS permanently recovers auditory neglect (Study 2). In Study 1, 20 patients with visuospatial neglect and auditory neglect in an auditory midline task following rightsided stroke were randomly allocated to an experimental and a control group matched for neglect severity and socio-demographic factors. Both groups showed a stable, pathological shift of their auditory subjective median plane (ASMP) in front space to the right side. During leftward OKS the experimental group showed a complete normalization of the shift of the ASMP, which endured until 30 min postStimulation, and returned almost to baseline values 24h after OKS. In contrast, the control group who viewed the identical but static dot pattern, showed neither change in their ASMP during this condition, nor any significant change at 30 min or 24h postStimulation. In Study 2, we show in two samples of neglect patients (N = 3 each) that repetitive leftward OKS with smooth pursuit eye movements as a therapy induces lasting improvements in auditory (the ASMP) and visual neglect while visual scanning therapy yielded no measurable effects on auditory and significantly smaller effects on visual neglect. In conclusion, the experiments show that a single session of OKS induces rapid though transient recovery from auditory neglect including a sustained effect after termination of Stimulation, while repetitive OKS therapy yields enduring and multimodal recovery from auditory and visual neglect. OKS therapy with pursuit eye movements therefore represents a multimodally effective and easily applicable technique for the treatment of auditory and visual neglect.
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repetitive Optokinetic Stimulation induces lasting recovery from visual neglect
Restorative Neurology and Neuroscience, 2006Co-Authors: Georg Kerkhoff, Ingo Keller, V Ritter, C MarquardtAbstract:Purpose: To evaluate whether repetitive Optokinetic Stimulation with active pursuit eye movements leads to substantial and greater recovery from visual neglect as compared to conventional visual scanning training. Methods: Two groups of five patients with leftsided hemineglect were consecutively collected and matched for clinical and demographic variables as well as neglect severity. One group received five treatment sessions of repetitive Optokinetic Stimulation (R-OKS) within one week, while the other group received the same amount of conventional visual scanning training (VST) using identical visual stimuli and setup. All patients were treated in a single-subject baseline design with treatment-free intervals before (14 days) and after specific neglect therapy (14 days). Dependent variables were the improvements in digit cancellation, visuoperceptual and visuomotor line bisection and visual size distortion during treatment. The transfer of treatment effects was assessed by a paragraph reading test. Results: The results showed superior effects of OKS treatment in all five patients which generalized across all tasks administered and remained stable at follow-up. In contrast, no significant improvements were obtained after VST training in any of these tasks, except in line bisection. Conclusion: We conclude that the presentation of moving visual stimulus displays with active smooth pursuit eye movements can be more efficient than conventional visual scanning training using static visual displays.
Marco Zorzi - One of the best experts on this subject based on the ideXlab platform.
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Spatial grounding of symbolic arithmetic: an investigation with Optokinetic Stimulation
Psychological Research, 2019Co-Authors: Elvio Blini, Marco Pitteri, Marco ZorziAbstract:Growing evidence suggests that mental calculation might involve movements of attention along a spatial representation of numerical magnitude. Addition and subtraction on nonsymbolic numbers (numerosities) seem to induce a “momentum” effect, and have been linked to distinct patterns of neural activity in cortical regions subserving attention and eye movements. We investigated whether mental arithmetic on symbolic numbers, a cornerstone of abstract mathematical reasoning, can be affected by the manipulation of overt spatial attention induced by Optokinetic Stimulation (OKS). Participants performed additions or subtractions of auditory two-digit numbers during horizontal (experiment 1) or vertical OKS (experiment 2), and eye movements were concurrently recorded. In both experiments, the results of addition problems were underestimated, whereas results of subtractions were overestimated (a pattern that is opposite to the classic Operational Momentum effect). While this tendency was unaffected by OKS, vertical OKS modulated the occurrence of decade errors during subtractions (i.e., fewer during downward OKS and more frequent during upward OKS). Eye movements, on top of the classic effect induced by OKS, were affected by the type of operation during the calculation phase, with subtraction consistently leading to a downward shift of gaze position and addition leading to an upward shift. These results highlight the pervasive nature of spatial processing in mental arithmetic. Furthermore, the preeminent effect of vertical OKS is in line with the hypothesis that the vertical dimension of space–number associations is grounded in universal (physical) constraints and, thereby, more robust than situated and culture-dependent associations with the horizontal dimension.
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larger smaller odd or even task specific effects of Optokinetic Stimulation on the mental number space
Journal of cognitive psychology, 2015Co-Authors: Mariagrazia Ranzini, Konstantinos Priftis, Marco Pitteri, Elvio Blini, Matteo Lisi, Barbara Treccani, Marco ZorziAbstract:Previous studies have shown that number processing can induce spatial biases in perception and action and can trigger the orienting of visuospatial attention. Few studies, however, have investigated how spatial processing and visuospatial attention influences number processing. In the present study, we used the Optokinetic Stimulation (OKS) technique to trigger eye movements and thus overt orienting of visuospatial attention. Participants were asked to stare at OKS, while performing parity judgements (Experiment 1) or number comparison (Experiment 2), two numerical tasks that differ in terms of demands on magnitude processing. Numerical stimuli were acoustically presented, and participants responded orally. We examined the effects of OKS direction (leftward or rightward) on number processing. The results showed that rightward OKS abolished the classic number size effect (i.e., faster reaction times for small than large numbers) in the comparison task, whereas the parity task was unaffected by OKS direction. The effect of OKS highlights a link between visuospatial orienting and processing of number magnitude that is complementary to the more established link between numerical and visuospatial processing. We suggest that the bidirectional link between numbers and space is embodied in the mechanisms subserving sensorimotor transformations for the control of eye movements and spatial attention.
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Optokinetic Stimulation Modulates Neglect for the Number Space: Evidence from Mental Number Interval Bisection
Frontiers in human neuroscience, 2012Co-Authors: Konstantinos Priftis, Francesca Meneghello, Marco Pitteri, Marco ZorziAbstract:Behavioral, neuropsychological, and neuroimaging data support the idea that numbers are represented along a mental number line (MNL), an analogical, visuo-spatial representation of number magnitude. The MNL is left-to-right oriented, with small numbers on the left and larger numbers on the right. Left neglect patients are impaired in processing the left side of the MNL and show a rightward deviation in the mental bisection of numerical intervals. In the present study we investigated the effects of Optokinetic Stimulation (OKS) -a technique inducing spatial attention shifts by means of activation of the Optokinetic nystagmus- on mental number interval bisection. One patient with left neglect following right hemisphere stroke (BG) and four control patients with right hemisphere damage, but without neglect, performed the mental number interval bisection task in three experimental conditions of OKS: static, leftward, and rightward. In the static condition, BG misbisected to the right of the true midpoint. BG misbisected to the left following leftward OKS, but again to the right of the midpoint following rightward OKS. In contrast, the performance of controls was not significantly affected by the direction of OKS. We argue that shifts of visuospatial attention, induced by OKS, may affect the mental number interval bisection, suggesting the presence of an interaction between the processing of number magnitude and the processing of the perceptual space, in patients with neglect for the mental number space.