Eye Movement Performance Research Articles

Effects of spatial congruency on saccade and visual discrimination performance in a dual-task paradigm.

The present study investigated the coupling of selection-for-perception and selection-for-action during saccadic eye movement planning in three dual-task experiments. We focused on the effects of spatial congruency of saccade target (ST) location and discrimination target (DT) location and the time between ST-cue and Go-signal (SOA) on saccadic eye movement performance. In two experiments, participants performed a visual discrimination task at a cued location while programming a saccadic eye movement to a cued location. In the third experiment, the discrimination task was not cued and appeared at a random location. Spatial congruency of ST-location and DT-location resulted in enhanced perceptual performance irrespective of SOA. Perceptual performance in spatially incongruent trials was above chance, but only when the DT-location was cued. Saccade accuracy and precision were also affected by spatial congruency showing superior performance when the ST- and DT-location coincided. Saccade latency was only affected by spatial congruency when the DT-cue was predictive of the ST-location. Moreover, saccades consistently curved away from the incongruent DT-locations. Importantly, the effects of spatial congruency on saccade parameters only occurred when the DT-location was cued; therefore, results from experiments 1 and 2 are due to the endogenous allocation of attention to the DT-location and not caused by the salience of the probe. The SOA affected saccade latency showing decreasing latencies with increasing SOA. In conclusion, our results demonstrate that visuospatial attention can be voluntarily distributed upon spatially distinct perceptual and motor goals in dual-task situations, resulting in a decline of visual discrimination and saccade performance.

The saccadic system does not compensate for the immaturity of the smooth pursuit system during visual tracking in children

Motor skills improve with age from childhood into adulthood, and this improvement is reflected in the performance of smooth pursuit eye movements. In contrast, the saccadic system becomes mature earlier than the smooth pursuit system. Therefore, the present study investigates whether the early mature saccadic system compensates for the lower pursuit performance during childhood. To answer this question, horizontal eye movements were recorded in 58 children (ages 5-16 yr) and 16 adults (ages 23-36 yr) in a task that required the combination of smooth pursuit and saccadic eye movements. Smooth pursuit performance improved with age. However, children had larger average position error during target tracking compared with adults, but they did not execute more saccades to compensate for their low pursuit performance despite the early maturity of their saccadic system. This absence of error correction suggests that children have a lower sensitivity to visual errors compared with adults. This reduced sensitivity might stem from poor internal models and longer processing time in young children.

Altered Accuracy of Saccadic Eye Movements in Children with Fetal Alcohol Spectrum Disorder

Prenatal exposure to alcohol is a major, preventable cause of neurobehavioral dysfunction in children worldwide. The measurement and quantification of saccadic eye movements is a powerful tool for assessing sensory, motor, and cognitive function. The quality of the motor process of an eye movement is known as saccade metrics. Saccade accuracy is 1 component of metrics, which to function optimally requires several cortical brain structures as well as an intact cerebellum and brain-stem. The cerebellum has frequently been reported to be damaged by prenatal alcohol exposure. This study, therefore, tested the hypothesis that children with fetal alcohol spectrum disorder (FASD) will exhibit deficits in the accuracy of saccades. A group of children with FASD (n = 27) between the ages of 8 and 16 and typically developing control children (n = 27) matched for age and sex, completed 3 saccadic eye movement tasks of increasing difficulty. Eye movement performance during the tasks was captured using an infrared eye tracker. Saccade metrics (e.g., velocity, amplitude, accuracy) were quantified and compared between the 2 groups for the 3 different tasks. Children with FASD were more variable in saccade endpoint accuracy, which was reflected by statistically significant increases in the error of the initial saccade endpoint and the frequency of additional, corrective saccades required to achieve final fixation. This increased variability in accuracy was amplified when the cognitive demand of the tasks increased. Children with FASD also displayed a statistically significant increase in response inhibition errors. These data suggest that children with FASD may have deficits in eye movement control and sensory-motor integration including cerebellar circuits, thereby impairing saccade accuracy.

Cognitive performance in high-altitude climbers: a comparative study of saccadic eye movements and neuropsychological tests

Impairment of cognitive performance during and after high-altitude climbing has been described in numerous studies and has mostly been attributed to cerebral hypoxia and resulting functional and structural cerebral alterations. To investigate the hypothesis that high-altitude climbing leads to cognitive impairment, we used of neuropsychological tests and measurements of eye movement (EM) performance during different stimulus conditions. The study was conducted in 32 mountaineers participating in an expedition to Muztagh Ata (7,546 m). Neuropsychological tests comprised figural fluency, line bisection, letter and number cancellation, and a modified pegboard task. Saccadic performance was evaluated under three stimulus conditions with varying degrees of cortical involvement: visually guided pro- and anti-saccades, and visuo-visual interaction. Typical saccade parameters (latency, mean sequence, post-saccadic stability, and error rate) were computed off-line. Measurements were taken at a baseline level of 440 m and at altitudes of 4,497, 5,533, 6,265, and again at 440 m. All subjects reached 5,533 m, and 28 reached 6,265 m. The neuropsychological test results did not reveal any cognitive impairment. Complete eye movement recordings for all stimulus conditions were obtained in 24 subjects at baseline and at least two altitudes and in 10 subjects at baseline and all altitudes. Measurements of saccade performances showed no dependence on any altitude-related parameter and were well within normal limits. Our data indicates that acclimatized climbers do not seem to suffer from significant cognitive deficits during or after climbs to altitudes above 7,500 m. We demonstrated that investigation of EMs is feasible during high-altitude expeditions.

Eye Movements Reveal Effects of Visual Content on Eye Guidance and Lexical Access during Reading

BackgroundNormal reading requires eye guidance and activation of lexical representations so that words in text can be identified accurately. However, little is known about how the visual content of text supports eye guidance and lexical activation, and thereby enables normal reading to take place.Methods and FindingsTo investigate this issue, we investigated eye movement performance when reading sentences displayed as normal and when the spatial frequency content of text was filtered to contain just one of 5 types of visual content: very coarse, coarse, medium, fine, and very fine. The effect of each type of visual content specifically on lexical activation was assessed using a target word of either high or low lexical frequency embedded in each sentenceResultsNo type of visual content produced normal eye movement performance but eye movement performance was closest to normal for medium and fine visual content. However, effects of lexical frequency emerged early in the eye movement record for coarse, medium, fine, and very fine visual content, and were observed in total reading times for target words for all types of visual content.ConclusionThese findings suggest that while the orchestration of multiple scales of visual content is required for normal eye-guidance during reading, a broad range of visual content can activate processes of word identification independently. Implications for understanding the role of visual content in reading are discussed.

Effects of haloperidol on cognition in schizophrenia patients depend on baseline performance: A saccadic eye movement study

Schizophrenic patients are heterogeneous with respect to voluntary eye movement performance, with some showing impairment (e.g., high antisaccade error rates) and others having intact performance. To investigate how this heterogeneity may correlate with different cognitive outcomes after treatment, we used a prosaccade and antisaccade task to investigate the effects of haloperidol in schizophrenic subjects at three time points: baseline (before medication), 3-5 days post-medication, and 12-14 days post-medication. We also investigated changes on the Stroop Task and the Positive and Negative Syndrome Scale (PANSS) in these same subjects. Results were compared to matched controls. When considered as a single patient group, haloperidol had no effects across sessions on reflexive and voluntary saccadic eye movements of schizophrenic patients. In contrast, the performance of the Control group improved slightly but significantly across sessions on the voluntary eye movement task. When each subject was considered separately, interestingly, for schizophrenic patients change in voluntary eye movement performance across sessions depended on the baseline performance in a non-monotonic manner. That is, there was maximal worsening of voluntary eye movement performance at an intermediate level of baseline performance and the worsening decreased on either side of this intermediate baseline level. When patients were divided into categorical subgroups (nonimpaired and impaired), consistent with the non-monotonic relationship, haloperidol worsened voluntary eye movement performance in the nonimpaired patients and improved performance in the impaired patients. These results were only partially reflected in the Stroop Test. Both patient subgroups showed clinically significant improvement over time as measured by the PANSS. These findings suggest that haloperidol has different effects on cognitive performance in impaired and nonimpaired schizophrenic patients that are not evident in clinical ratings based on the PANSS. Given that good cognitive function is important for long-term prognosis and that there is heterogeneity in schizophrenia, these findings are critical for optimal evaluation and treatment of schizophrenic patients.

Effect of Stimulus Type on the Eye Movements of Children

The authors investigated whether pictures elicit superior response rates and eye movement dynamics on saccade and pursuit tasks than do dots or spots of light and whether the need for more interesting stimuli is age dependent. Using video eye tracking, horizontal eye movements were investigated in children and adults using dots and small colored pictures as stimuli. Saccade data were obtained from 61 people and pursuit data from 53 people, ages 3 to 30 years, with no known ocular, ocular motor, neurologic, or systemic disease. Saccadic stimuli were randomly presented in steps ranging in size from 5° to 30°. Pursuits at four velocities (5°/s, 10°/s, 20°/s, and 30°/s) were tested using step ramp stimuli. Picture targets result in age-dependent improvements in ocular motor responses compared with dots. With the exception of saccadic accuracy, the youngest children are most affected by the type of target. Adults are affected very little. For pictures, saccadic response rates (t((60)) = 4.30, P < 0.001), saccadic peak velocities (t((60)) = 2.24, P = 0.03), saccadic accuracy (t((59)) = 2.34, P = 0.02), and closed-loop pursuit gains (F((3,50)) = 2.86, P = 0.046) are higher. Saccadic error rates (t((60)) = 3.91, P < 0.001) and saccadic latencies (t((59)) = 9.5, P < 0.001) are lower with pictures. Stimulus characteristics can affect response rates and eye movement dynamics, particularly in young children. To avoid underestimation of eye movement performance in young children, it is important to use meaningful targets. Furthermore, when comparing the ocular motor performance of children across studies one must consider the type of stimuli used.

NR2A subunit of the N-methyl d-aspartate receptors are required for potentiation at the mossy fiber to granule cell synapse and vestibulo-cerebellar motor learning

Traditionally studies aimed at elucidating the molecular mechanisms underlying cerebellar motor learning have been focused on plasticity at the parallel fiber to Purkinje cell synapse. In recent years, however, the concept is emerging that formation and storage of memories are both distributed over multiple types of synapses at different sites. Here, we examined the potential role of potentiation at the mossy fiber to granule cell synapse, which occurs upstream to plasticity in Purkinje cells. We show that null-mutants of N-methyl d-aspartate-NR2A receptors (NMDA-NR2A−/− mice) have impaired induction of postsynaptic long-term potentiation (LTP) at the mossy fiber terminals and a reduced ability to raise the granule cell synaptic excitation, while the basic excitatory output of the mossy fibers is unaffected. In addition, we demonstrate that these NR2A−/− mutants as well as mutants in which the C terminal in the NR2A subunit is selectively truncated (NR2AΔC/ΔC mice) have deficits in phase reversal adaptation of their vestibulo-ocular reflex (VOR), while their basic eye movement performance is similar to that of wild type littermates. These results indicate that NMDA-NR2A mediated potentiation at the mossy fiber to granule cell synapse is not required for basic motor performance, and they raise the possibility that it may contribute to some forms of vestibulo-cerebellar memory formation.

P1-23 Effects of anti-saccade training with neck flexion on eye movement performance, presaccadic potentials and prefrontal hemodynamics in the elderly

P1-23 Effects of anti-saccade training with neck flexion on eye movement performance, presaccadic potentials and prefrontal hemodynamics in the elderly

Effects of anti-saccade training with neck flexion on eye movement performance, presaccadic potentials and prefrontal hemodynamics in the elderly

Anti-saccade performance, with strong contributions from frontal brain regions, reportedly deteriorates with age and maintenance of neck flexion and is known to cause brain activation. We investigated the effects of anti-saccade training on eye movement performance and frontal activity, and synergistic effects of training with neck flexion in the elderly. Thirty elderly individuals were divided into three equal groups: training group at neck resting position (NRT); training group at 20° neck flexion position (NFT); and untrained group. NRT and NFT performed approximately 200 anti-saccades (a block of 10-12 anti-saccades for 30s×20 blocks) per day over 3weeks. Before and after training, horizontal eye movement, presaccadic potentials, and oxygenated hemoglobin concentration (oxy-Hb) in the prefrontal cortex during anti-saccades were tested in neck resting and 20° neck flexion conditions. In NRT and NFT, reaction time (-50ms), percentage of erroneous saccades (-24%), and period between peak of presaccadic negativity and onset of spike potential (-16ms) were significantly decreased through training. Only in NFT, after training, slight shortening of reaction time associated with neck flexion was recognized (-10ms), and peak amplitude of presaccadic negativity was increased in both test neck conditions. Oxy-Hb was not significantly affected by trainings and test neck conditions. We demonstrated that in the elderly, anti-saccade training with both neck postures improved performance and facilitated related neural pathways. Moreover, training with neck flexion showed small but synergistic effects on performance and frontal activity. However, these trainings would be insufficient for elderly individuals to automatically control anti-saccade.

Eye Movement Performance and Prefrontal Hemodynamics during Saccadic Eye Movements in the Elderly

No previous study has investigated age-related changes in prefrontal hemodynamics during saccade tasks in a large number of elderly adults. The purpose of this study was to evaluate prefrontal activity related to the performance of anti-saccade in the elderly using near-infrared spectroscopy (NIRS). Ninety-six elderly adults and 22 young adults performed pro- and anti-saccade tasks. Measures included reaction times of both saccades, error rate during anti-saccade, and concentration of oxyhemoglobin (Deltaoxy-Hb) in the prefrontal cortex during both saccades. Saccade performance, especially error rate, was significantly poorer in the elderly than the young. In the elderly, error rates were widely distributed from 5% to 100%. In about half (48%) of the elderly, error rates were distributed under the mean+3 standard deviations (48%) for the young, and Deltaoxy-Hb did not differ significantly from that in the young. Elderly subjects whose anti-saccade reaction time was over the regression line (of reaction time in anti-saccade to that in pro-saccade in the young)+2 standard errors showed a strong positive correlation (r=0.79) between Deltaoxy-Hb and error rate, as did those whose error rate exceeded 48%. In the elderly subjects whose error rates exceeded 90%, Deltaoxy-Hb was extremely small and deviated greatly from the correlation between Deltaoxy-Hb and error rate. Based on these findings, we propose a method of evaluating inhibitory function and attention allocation in anti-saccade performance, which is mainly related to the prefrontal cortex, in the elderly, using NIRS.

Precision of speed discrimination and smooth pursuit eye movements

Several studies have shown that the precision of smooth pursuit eye speed can match perceptual speed discrimination thresholds during the steady-state phase of pursuit [Kowler, E., & McKee, S. (1987). Sensitivity of smooth eye movement to small differences in target velocity. Vision Research, 27, 993–1015; Gegenfurtner, K., Xing, D., Scott, B., & Hawken, M. (2003). A comparison of pursuit eye movement and perceptual performance in speed discrimination. Journal of Vision, 3, 865–876]. Recently, Osborne et al. [Osborne, L. C., Lisberger, S. G., & Bialek, W. (2005). A sensory source for motor variation. Nature, 437, 412–416; Osborne, L. C., Hohl, S. S., Bialek, W., & Lisberger S. G. (2007). Time course of precision in smooth-pursuit eye movements of monkeys. Journal of Neuroscience, 27, 2987–2998] claimed that pursuit precision during the initiation phase of pursuit also matches the sensory variability, implying that there is no motor noise added during pursuit initiation. However, these results were derived from a comparison of monkey pursuit data to human perceptual data from the literature, which were obtained with different stimuli. To directly compare precision for perception and pursuit, we measured pursuit and perceptual variability in the same human observers using the same stimuli. Subjects had to pursue a Gaussian blob in a step-ramp paradigm and give speed judgments on the same or in different trials. Speed discrimination thresholds were determined for different presentation durations. The analysis of pursuit precision was performed for short intervals containing the initiation period only and also for longer intervals including steady-state pursuit. In agreement with published studies, we found that the Weber fractions for psychophysical speed discrimination were fairly constant for different presentation durations, even for the shortest presentation duration of 150ms. Pursuit variability was 3–4 times as high for the analysis interval (300ms) containing the open-loop phase only. For pursuit analysis intervals of 400–500ms, pursuit variability approached perceptual variability. Our results show that, for the stimuli we used, the motor system contributes at least 50% to the total variability of smooth pursuit eye movements during the initiation phase.

Complementary Actions of BDNF and Neurotrophin-3 on the Firing Patterns and Synaptic Composition of Motoneurons

Neurotrophins, as target-derived factors, are essential for neuronal survival during development, but during adulthood, their scope of actions widens to become also mediators of synaptic and morphological plasticity. Target disconnection by axotomy produces an initial synaptic stripping ensued by synaptic rearrangement upon target reinnervation. Using abducens motoneurons of the oculomotor system as a model for axotomy, we report that trophic support by brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3) or a mixture of both, delivered to the stump of severed axons, results in either the prevention of synaptic stripping when administered immediately after lesion or in a promotion of reinnervation of afferents to abducens motoneurons once synaptic stripping had occurred, in concert with the recovery of synaptic potentials evoked from the vestibular nerve. Synaptotrophic effects, however, were larger when both neurotrophins were applied together. The axotomy-induced reduction in firing sensitivities related to eye movements were also restored to normal values when BDNF and NT-3 were administered, but discharge characteristics recovered in a complementary manner when only one neurotrophin was used. This is the first report to show selective retrograde trophic dependence of circuit-driven firing properties in vivo indicating that NT-3 restored the phasic firing, whereas BDNF supported the tonic firing of motoneurons during eye movement performance. Therefore, our data report a link between the synaptotrophic actions of neurotrophins, retrogradely delivered, and the alterations of neuronal firing patterns during motor behaviors. These trophic actions could be responsible, in part, for synaptic rearrangements that alter circuit stability and synaptic balance during plastic events of the brain.

Evidence of anticipatory eye movements in the spatial Hebb repetition effect: Insights for modeling sequence learning.

In the present study, the authors offer a window onto the mechanisms that drive the Hebb repetition effect through the analysis of eye movement and recall performance. In a spatial serial recall task in which sequences of dots are to be remembered in order, when one particular series is repeated every 4 trials, memory performance markedly improves over repetitions. This is known as the Hebb repetition effect. Eye movement recorded during the presentation of the to-be-remembered (TBR) information revealed that for the repeated sequence, participants fixated the location of the next TBR location before the actual presentation of the dot. The extent to which a TBR location was anticipated increased over repetition and occurred only for post-initial positions of the repeated sequence. Eye movement-based rehearsal activity was related to recall performance but not to sequence learning. The findings provide further evidence of anticipatory behavior in sequence learning and place key constraints on modeling the Hebb repetition effect.

Estradiol Improves Cerebellar Memory Formation by Activating Estrogen Receptor β

Learning motor skills is critical for motor abilities such as driving a car or playing piano. The speed at which we learn those skills is subject to many factors. Yet, it is not known to what extent gonadal hormones can affect the achievement of accurate movements in time and space. Here we demonstrate via different lines of evidence that estradiol promotes plasticity in the cerebellar cortex underlying motor learning. First, we show that estradiol enhances induction of long-term potentiation at the parallel fiber to Purkinje cell synapse, whereas it does not affect long-term depression; second, we show that estradiol activation of estrogen receptor beta receptors in Purkinje cells significantly improves gain-decrease adaptation of the vestibulo-ocular reflex, whereas it does not affect general eye movement performance; and third, we show that estradiol increases the density of parallel fiber to Purkinje cell synapses, whereas it does not affect the density of climbing fiber synapses. We conclude that estradiol can improve motor skills by potentiating cerebellar plasticity and synapse formation. These processes may be advantageous during periods of high estradiol levels of the estrous cycle or pregnancy.

Differences in cortical activation during smooth pursuit and saccadic eye movements following cerebellar lesions

Current evidence supports the proposal that the cerebellum mediates the activity of other brain areas involved in the control of eye movements. Most of the evidence so far has concentrated on the vermis and flocculi as the cerebellar agents of oculomotor control. But there is also evidence for an involvement of the cerebellar hemispheres in eye movement control. Straube et al. (Ann Neurol 42:891-898, 1997) showed that lateral hemispheric lesions affect initiation of smooth pursuit (SPEM) and saccadic eye movements. Ron and Robinson (J Neurophysiol 36:1004-1022, 1973) evoked smooth pursuit and saccadic eye movements by electrical stimulation of crus I and II, as well as in the dentate nuclei of the monkey. Functional MRI studies also provide evidence that the cerebellar hemispheres play a significant role in SPEM and saccadic eye movements. To clarify the role of the cerebral hemispheres in eye movement control we compared the eye movement related blood oxygen level dependent (BOLD) responses of 12 patients with cerebellar lesions due to stroke with those of an aged-matched healthy control group. Six patients showed oculomotor abnormalities such as dysmetric saccades or saccadic SPEM during the experiment. The paradigm consisted of alternating blocks of fixation, visually guided saccades and visually guided SPEM. A nonparametric random-effects group analysis showed a degraded pattern of activation in the patient group during the performance of SPEM and saccadic eye movements in posterior parietal areas putatively containing the parietal eye fields.

Saccadic Eye Movement Velocity Measured with the Infrared Reflection and Search Coil Eye-Tracking Systems in Patients with Thyroid-Associated Ophthalmopathy

Background Assessment of changes in saccade velocity may be useful in the early detection of thyroid-associated ophthalmopathy (TAO). Two eye-tracking systems were used to measure the velocity of saccadic eye movements in patients with TAO. Method Fourteen patients with active TAO and 14 healthy controls were enrolled for recordings with two eye-tracking systems: the magnetic scleral search coil (MSC; Skalar Medical) and the infrared reflection systems (IR; Orbit XY-1000). The MSC is generally considered the “gold standard” method for tracking of rapid eye movements. The IR system uses novel computer technology and is based on sampling of reflected infrared light from the surface of the eyes. Main sequence plots constructed from the recorded saccadic peak velocity and amplitude were analyzed for differences between patients and healthy controls. Results There were no significant differences between patients with TAO and healthy controls in the constructed main sequence plots of maximum velocity (VMAX) and the slope constant (C). Conclusions Main sequence analysis of saccadic eye movements was not useful for detecting TAO in this experimental setting with either of the two eye-tracking methods. This is hypothesized to be due to compensation for the early orbital changes in TAO by neural adaptation of the saccades in the brain stem. The contradictory results between this and previous studies cannot be easily explained. We assume that there is a large heterogeneity in the saccadic eye movement performance in both the normal population and the TAO-population. Also, differences in the study design may cause dissimilar outcomes and hence incoherent conclusions. A non-invasive recording system that is able to generate a minimum amount of intra- and inter-individual variability and a study design where normal variability can be reduced to a minimum may be useful for future identification of early eye muscle changes in TAO.

Detection of floccular hypometabolism in downbeat nystagmus by fMRI

The authors evaluated floccular activity with fMRI during the performance of vertical smooth pursuit eye movements in four patients with downbeat nystagmus (DBN) due to cerebellar degeneration and in 16 healthy controls. Region of interest analysis revealed a significantly diminished activation of both floccular lobes during downward but not upward pursuit in DBN. These imaging data support the view that a functional deficiency of the flocculi in downward pursuit causes DBN.

Shared decision signal explains performance and timing of pursuit and saccadic eye movements

Each voluntary eye movement provides physical evidence of a visuomotor choice about where and when to look. Primates choose visual targets with two types of voluntary eye movements, pursuit and saccades, although the exact mechanism underlying their coordination remains unknown. Are pursuit and saccades guided by the same decision signal? The present study compares pursuit and saccadic choices using techniques borrowed from psychophysics and models of response time. Human observers performed a luminance discrimination task and indicated their choices with eye movements. Because the stimuli moved horizontally and were offset vertically, subjects' tracking responses consisted of combinations of both pursuit and saccadic eye movements. For each of two signal strengths, we constructed speed-accuracy curves for pursuit and saccades. We found that speed-accuracy curves for pursuit and saccades have the same shape, but are time-shifted with respect to one another. We argue that this pattern occurs because pursuit and saccades share a decision signal, but utilize different response thresholds and are subject to different motor processing delays.

Parametric modulation of cortical activation during smooth pursuit with and without target blanking. An fMRI study

Smooth pursuit eye movements (SPEM) are performed to track slowly moving visual targets and are accompanied by saccades whenever foveal representation is lost. In the present study, we correlated the cerebral activation as assessed by functional magnetic resonance imaging with parameters of eye movement performance in order to determine the cortical areas involved in the retinal and extraretinal processing of maintaining smooth pursuit velocity (SPV) and generating saccades in 16 healthy males. The stimulus consisted of a target moving at a constant velocity of 10°/s with and without target blanking. During constant target presentation, SPV was positively correlated with the BOLD signal in the right V5 complex and negatively correlated with the BOLD response in the left dorsolateral prefrontal cortex (DLPFC). In the condition with target blanking, additional negative correlations with SPV were found in the left frontal eye field (FEF), the left parietoinsular vestibular cortex (PIVC) and the left angular gyrus. Saccadic frequency was negatively correlated with activations of the right mesial intraparietal sulcus (IPS) during both conditions and the right premotor area during continuous target presentation. We conclude that V5 is directly related to the maintenance of an optimal smooth pursuit velocity during visual feedback, whereas the FEF, PFC, angular gyrus and PIVC are involved in reconstitution and prediction whenever SPV decreases, especially during maintenance of smooth pursuit in the absence of a visual target. Furthermore, we suggest that parietal areas are related to the suppression of saccades during smooth pursuit.