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Kikuro Fukushima - One of the best experts on this subject based on the ideXlab platform.
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discharge of pursuit neurons in the caudal part of the Frontal Eye Fields during cross axis vestibular pursuit training in monkeys
Experimental Brain Research, 2009Co-Authors: Keishi Fujiwara, Sergei A. Kurkin, Teppei Akao, Kikuro FukushimaAbstract:Previous studies in monkeys have shown that pursuit training during orthogonal whole body rotation results in task-dependent, predictive pursuit Eye movements. We examined whether pursuit neurons in the Frontal Eye Fields (FEF) are involved in predictive pursuit induced by vestibular-pursuit training. Two monkeys were rotated horizontally at 20°/s for 0.5 s either rightward or leftward with random inter-trial intervals. This chair motion trajectory was synchronized with orthogonal target motion at 20°/s for 0.5 s either upward or downward. Monkeys were rewarded for pursuing the target. Vertical pursuit Eye velocities and discharge of 23 vertical pursuit neurons to vertical target motion were compared before training and during the last 5 min of the 25–45 min training. The latencies of discharge modulation of 61% of the neurons (14/23) shortened after vestibular-pursuit training in association with a shortening of pursuit latency. However, their discharge modulation occurred after 100 ms following the onset of pursuit Eye velocity. Only four neurons (4/23 = 17%) discharged before the Eye movement onset. A significant change was not observed in Eye velocity and FEF pursuit neuron discharge during pursuit alone after training without vestibular stimulation. Vestibular stimulation alone without a target after training induced no clear response. These results suggest that the adaptive change in response to pursuit prediction was induced by vestibular inputs in the presence of target pursuit. FEF pursuit neurons are unlikely to be involved in the initial stage of generating predictive Eye movements. We suggest that they may participate in the maintenance of predictive pursuit.
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Eye pursuit and reafferent head movement signals carried by pursuit neurons in the caudal part of the Frontal Eye Fields during head free pursuit
Cerebral Cortex, 2009Co-Authors: Kikuro Fukushima, Sergei A. Kurkin, Teppei Akao, Junko Fukushima, Satoshi Kasahara, B W PetersonAbstract:Eye and head movements are coordinated during head-free pursuit. To examine whether pursuit neurons in Frontal Eye Fields (FEF) carry gaze-pursuit commands that drive both Eye-pursuit and head-pursuit, monkeys whose heads were free to rotate about a vertical axis were trained to pursue a juice feeder with their head and a target with their Eyes. Initially the feeder and target moved synchronously with the same visual angle. FEF neurons responding to this gaze-pursuit were tested for Eye-pursuit of target motion while the feeder was stationary and for head-pursuit while the target was stationary. The majority of pursuit neurons exhibited modulation during head-pursuit, but their preferred directions during Eye-pursuit and head-pursuit were different. Although peak modulation occurred during head movements, the onset of discharge usually was not aligned with the head movement onset. The minority of neurons whose discharge onset was so aligned discharged after the head movement onset. These results do not support the idea that the head-pursuit–related modulation reflects head-pursuit commands. Furthermore, modulation similar to that during head-pursuit was obtained by passive head rotation on stationary trunk. Our results suggest that FEF pursuit neurons issue gaze or Eye movement commands during gaze-pursuit and that the head-pursuit–related modulation primarily reflects reafferent signals resulting from head movements.
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Discharge of pursuit-related neurons in the caudal part of the Frontal Eye Fields in juvenile monkeys with up–down pursuit asymmetry
Experimental Brain Research, 2009Co-Authors: Sergei A. Kurkin, Teppei Akao, Junko Fukushima, Kikuro FukushimaAbstract:The smooth-pursuit system uses retinal image-slip-velocity information of target motion to match Eye velocity to actual target velocity. The caudal part of the Frontal Eye Fields (FEF) contains neurons whose activity is related to direction and velocity of smooth-pursuit Eye movements (pursuit neurons), and these neurons are thought to issue a pursuit command. During normal pursuit in well-trained adult monkeys, a pursuit command is usually not differentiable from the actual Eye velocity. We examined whether FEF pursuit neurons signaled the actual Eye velocity during pursuit in juvenile monkeys that exhibited intrinsic differences between upward and downward pursuit capabilities. Two, head-stabilized Japanese monkeys of 4 years of age were tested for sinusoidal vertical pursuit of target motion at 0.2–1.2 Hz (±10°, peak target velocity 12.5–75.0°/s). Gains of downward pursuit were 0.8–0.9 at 0.2–1.0 Hz, and peak downward Eye velocity increased up to ~60°/s linearly with target velocity, whereas peak upward Eye velocity saturated at 15–20°/s. The majority of downward FEF pursuit neurons increased the amplitude of their discharge modulation almost linearly up to 1.2 Hz. The majority of upward FEF pursuit neurons also increased amplitude of modulation nearly linearly as target frequency increased, and the regression slope was similar to that of downward pursuit neurons despite the fact that upward peak Eye velocity saturated at ~0.5 Hz. These results indicate that the responses of the majority of upward FEF pursuit neurons did not signal the actual Eye velocity during pursuit. We suggest that their activity reflected primarily the required Eye velocity.
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Activity of pursuit neurons in the caudal part of the Frontal Eye Fields during static roll-tilt
Experimental Brain Research, 2007Co-Authors: Sergei A. Kurkin, Teppei Akao, Junko Fukushima, Kikuro FukushimaAbstract:The smooth-pursuit system and vestibular system interact to keep the retinal target image on the fovea during head and/or whole body movements. The caudal part of the Frontal Eye Fields (FEF) in the fundus of arcuate sulcus contains pursuit neurons and the majority of them respond to vestibular stimulation induced by whole-body rotation, that activates primarily semi-circular canals, and by whole-body translation, that activates otoliths. To examine whether coordinate frames representing FEF pursuit signals are orbital or earth-vertical, we compared preferred directions during upright and static, whole-body roll-tilt in head- and trunk-restrained monkeys. Preferred directions (re monkeys’ head/trunk axis) of virtually all pursuit neurons tested ( n = 21) were similar during upright and static whole-body roll-tilt. The slight shift of preferred directions of the majority of neurons could be accounted for by ocular counter-rolling. The mean (±SD) differences in preferred directions between upright and 40° right ear down and between upright and 40° left ear down were 6° (±6°) and 5° (±5°), respectively. Visual motion preferred directions were also similar in five pursuit neurons tested. To examine whether FEF pursuit neurons could signal static whole-body roll-tilt, we compared mean discharge rates of 29 neurons during fixation of a stationary spot while upright and during static, whole-body roll-tilt. Virtually all neurons tested (28/29) did not exhibit a significant difference in mean discharge rates between the two conditions. These results suggest that FEF pursuit neurons do not signal static roll-tilt and that they code pursuit signals in head/trunk-centered coordinates.
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role of vestibular signals in the caudal part of the Frontal Eye Fields in pursuit Eye movements in three dimensional space
Annals of the New York Academy of Sciences, 2005Co-Authors: Kikuro Fukushima, Sergei A. Kurkin, Teppei Akao, Junko FukushimaAbstract:: For accurate visual information about objects of interest moving slowly in three-dimensional (3D) space, primates with binocular Fields use both Frontal smooth-pursuit (Frontal-pursuit) and vergence Eye movements (i.e., depth pursuit) to maintain the images of the objects precisely on the foveae of left and right Eyes. Moreover, during head or whole-body movement, both Frontal- and depth-pursuit systems must interact with the vestibular system to minimize slip of the retinal mages that degrades image quality considerably. The caudal part of the Frontal Eye Fields (FEF) contains many Frontal-pursuit neurons. Previous studies have shown that a majority of pursuit neurons there discharge for both Frontal pursuit and vergence and carry pursuit-in-3D signals. To understand how vestibular inputs interact with pursuit-in-3D signals, three different experiments that examined the nature of vestibular signals in the caudal FEF are described in this review. A majority of caudal FEF pursuit neurons responded to whole-body rotation with preferred directions similar to Frontal-pursuit directions and carried Frontal gaze (Eye-in-space) velocity signals. They were activated in association with adaptive pursuit Eye movements induced by cross-axis pursuit-vestibular interactions. During fore/aft and right/left translation in complete darkness, they were also modulated with preferred directions of many neurons similar to pursuit-preferred directions. Previous studies showed that caudal FEF pursuit neurons also receive visual signals about target motion. Taken together, these results suggest that the caudal FEF coordinates its various inputs to provide signals for accurate Eye-movement-in-space commands.
Brian D Corneil - One of the best experts on this subject based on the ideXlab platform.
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Frontal Eye field inactivation alters the readout of superior colliculus activity for saccade generation in a task dependent manner
bioRxiv, 2019Co-Authors: Tyler R Peel, Suryadeep Dash, Stephen G Lomber, Brian D CorneilAbstract:Abstract Saccades require a spatiotemporal transformation of activity between the intermediate layers of the superior colliculus (iSC) and downstream brainstem burst generator. The dynamic linear ensemble-coding model (Goossens and Van Opstal, 2006) proposes that each iSC spike contributes a fixed mini-vector to saccade displacement. Although biologically-plausible, this model assumes cortical areas like the Frontal Eye Fields (FEF) simply provide the saccadic goal to be executed by the iSC and brainstem burst generator. However, the FEF and iSC operate in unison during saccades, and a pathway from the FEF to the brainstem burst generator that bypasses the iSC exists. Here, we investigate the impact of large yet reversible inactivation of the FEF on iSC activity in the context of the model across four saccade tasks. We exploit the overlap of saccade vectors generated when the FEF is inactivated or not, comparing the number of iSC spikes for metrically-matched saccades. We found that the iSC emits fewer spikes for metrically-matched saccades during FEF inactivation. The decrease in spike count is task-dependent, with a greater decrease accompanying more cognitively-demanding saccades. Our results show that FEF integrity influences the readout of iSC activity in a task-dependent manner. We propose that the dynamic linear ensemble-coding model be modified so that FEF inactivation increases the gain of a readout parameter, effectively increasing the influence of a single iSC spike. We speculate that this modification could be instantiated by a direct pathway from the FEF to the omnipause region that modulates the excitability of the brainstem burst generator. Significance statement One of the enduring puzzles in the oculomotor system is how it achieves the spatiotemporal transformation, converting spatial activity within the intermediate layers of the superior colliculus (iSC) into a rate code within the brainstem burst generator. The spatiotemporal transformation has traditionally been viewed as the purview of the oculomotor brainstem. Here, within the context of testing a biologically-plausible model of the spatiotemporal transformation, we show that reversible inactivation of the Frontal Eye Fields (FEF) decreases the number of spikes issued by the iSC for metrically-matched saccades, with greater decreases accompanying more cognitively-demanding tasks. These results show that signals from the FEF influence the spatiotemporal transformation.
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Frontal Eye field inactivation diminishes superior colliculus activity but delayed saccadic accumulation governs reaction time increases
The Journal of Neuroscience, 2017Co-Authors: Tyler R Peel, Suryadeep Dash, Stephen G Lomber, Brian D CorneilAbstract:Stochastic accumulator models provide a comprehensive framework for how neural activity could produce behavior. Neural activity within the Frontal Eye Fields (FEFs) and intermediate layers of the superior colliculus (iSC) support such models for saccade initiation by relating variations in saccade reaction time (SRT) to variations in such parameters as baseline, rate of accumulation of activity, and threshold. Here, by recording iSC activity during reversible cryogenic inactivation of the FEF in four male nonhuman primates, we causally tested which parameter(s) best explains concomitant increases in SRT. While FEF inactivation decreased all aspects of ipsilesional iSC activity, decreases in accumulation rate and threshold poorly predicted accompanying increases in SRT. Instead, SRT increases best correlated with delays in the onset of saccade-related accumulation. We conclude that FEF signals govern the onset of saccade-related accumulation within the iSC, and that the onset of accumulation is a relevant parameter for stochastic accumulation models of saccade initiation. SIGNIFICANCE STATEMENT The superior colliculus (SC) and Frontal Eye Fields (FEFs) are two of the best-studied areas in the primate brain. Surprisingly, little is known about what happens in the SC when the FEF is temporarily inactivated. Here, we show that temporary FEF inactivation decreases all aspects of functionally related activity in the SC. This combination of techniques also enabled us to relate changes in SC activity to concomitant increases in saccadic reaction time (SRT). Although stochastic accumulator models relate SRT increases to reduced rates of accumulation or increases in threshold, such changes were not observed in the SC. Instead, FEF inactivation delayed the onset of saccade-related accumulation, emphasizing the importance of this parameter in biologically plausible models of saccade initiation.
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Frontal Eye field inactivation diminishes superior colliculus activity but delayed saccadic accumulation governs reaction time increases
bioRxiv, 2017Co-Authors: Tyler R Peel, Suryadeep Dash, Stephen G Lomber, Brian D CorneilAbstract:Stochastic accumulator models provide a comprehensive framework for how neural activity could produce behavior. Neural activity within the Frontal Eye Fields (FEF) and intermediate layers of the superior colliculus (iSC) support such models for saccade initiation, by relating variations in saccade reaction time (SRT) to variations in parameters such as baseline, rate of accumulation of activity, or threshold. Here, by recording iSC activity during reversible cryogenic inactivation of the FEF in non-human primates, we causally test which parameter(s) best explains concomitant increases in SRT. While FEF inactivation decreased all aspects of ipsilesional iSC activity, decreases in accumulation rate and threshold poorly predicted accompanying increases in SRT. Instead, SRT increases best correlated with delays in the onset of saccade-related accumulation. We conclude that FEF signals govern the onset of saccade-related accumulation within the iSC, and that the onset of accumulation is a relevant parameter for stochastic accumulation models of saccade initiation.
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transient pupil dilation after subsaccadic microstimulation of primate Frontal Eye Fields
The Journal of Neuroscience, 2016Co-Authors: Sebastian J Lehmann, Brian D CorneilAbstract:Pupillometry provides a simple and noninvasive index for a variety of cognitive processes, including perception, attention, task consolidation, learning, and memory. The neural substrates by which such cognitive processes influence pupil diameter remain somewhat unclear, although cortical inputs to the locus coeruleus mediating arousal are likely involved. Changes in pupil diameter also accompany covert orienting; hence the oculomotor system may provide an alternative substrate for cognitive influences on pupil diameter. Here, we show that low-level electrical microstimulation of the primate Frontal Eye Fields (FEFs), a cortical component of the oculomotor system strongly connected to the intermediate layers of the superior colliculus (SCi), evoked robust pupil dilation even in the absence of evoked saccades. The magnitude of such dilation scaled with increases in stimulation parameters, depending strongly on the intensity and number of pulses. Although there are multiple pathways by which FEF stimulation could cause pupil dilation, the timing and profile of dilation closely resembled that evoked by SCi stimulation. Moreover, pupil dilation evoked from the FEFs increased when presumed oculomotor activity was higher at the time of stimulation. Our findings implicate the oculomotor system as a potential substrate for how cognitive processes can influence pupil diameter. We suggest that a pathway from the Frontal cortex through the SCi operates in parallel with Frontal inputs to arousal circuits to regulate task-dependent modulation of pupil diameter, perhaps indicative of an organization wherein one pathway assumes primacy for a given cognitive process. SIGNIFICANCE STATEMENT Pupillometry (the measurement of pupil diameter) provides a simple and noninvasive index for a variety of cognitive processes, offering a biomarker that has value in both health and disease. But how do cognitive processes influence pupil diameter? Here, we show that low-level stimulation of the primate Frontal Eye Fields can induce robust pupil dilation without saccades. Pupil dilation scaled with the number and intensity of stimulation pulses and varied with endogenous oculomotor activity at the time of stimulation. The oculomotor system therefore provides a plausible pathway by which cognitive processes may influence pupil diameter, perhaps operating in conjunction with systems regulating arousal.
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neck muscle responses evoked by transcranial magnetic stimulation of the human Frontal Eye Fields
European Journal of Neuroscience, 2011Co-Authors: Samanthi C Goonetilleke, Paul L Gribble, Seyed M Mirsattari, T Doherty, Brian D CorneilAbstract:Transcranial magnetic stimulation (TMS) provides a non-invasive means of investigating brain function. Whereas TMS of the human Frontal Eye Fields (FEFs) does not induce saccades, electrical stimulation of the monkey FEF evokes Eye-head gaze shifts, with neck muscle responses evoked at stimulation levels insufficient to evoke a saccade. These animal results motivated us to examine whether TMS of the FEF (TMS-FEF) in humans evokes a neck muscle response. Subjects performed memory-guided saccades to the left or right while TMS (two pulses at 20 Hz) was delivered on 30% of trials to the left FEF coincident with saccade instruction. As reported previously, TMS-FEF decreased contralateral saccade reaction times. We simultaneously recorded the activity of splenius capitis (SPL) (an ipsilateral head turner). TMS-FEF evoked a lateralized increase in the activity of the right SPL but not the left SPL, consistent with the recruitment of a contralateral head-turning synergy. In some subjects, the evoked neck muscle response was time-locked to stimulation, whereas in others the evoked response occurred around the time of the saccade. Importantly, evoked responses were greater when TMS was applied to the FEF engaged in contralateral saccade preparation, with even greater evoked responses preceding shorter latency saccades. These results provide new insights into both the nature of TMS and the human oculomotor system, demonstrating that TMS-FEF engages brainstem oculomotor circuits in a manner consistent with a general role in Eye-head gaze orienting. Our results also suggest that pairing neck muscle recordings with TMS-FEF provides a novel way of assaying the covert preparation of oculomotor plans.
Junko Fukushima - One of the best experts on this subject based on the ideXlab platform.
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Eye pursuit and reafferent head movement signals carried by pursuit neurons in the caudal part of the Frontal Eye Fields during head free pursuit
Cerebral Cortex, 2009Co-Authors: Kikuro Fukushima, Sergei A. Kurkin, Teppei Akao, Junko Fukushima, Satoshi Kasahara, B W PetersonAbstract:Eye and head movements are coordinated during head-free pursuit. To examine whether pursuit neurons in Frontal Eye Fields (FEF) carry gaze-pursuit commands that drive both Eye-pursuit and head-pursuit, monkeys whose heads were free to rotate about a vertical axis were trained to pursue a juice feeder with their head and a target with their Eyes. Initially the feeder and target moved synchronously with the same visual angle. FEF neurons responding to this gaze-pursuit were tested for Eye-pursuit of target motion while the feeder was stationary and for head-pursuit while the target was stationary. The majority of pursuit neurons exhibited modulation during head-pursuit, but their preferred directions during Eye-pursuit and head-pursuit were different. Although peak modulation occurred during head movements, the onset of discharge usually was not aligned with the head movement onset. The minority of neurons whose discharge onset was so aligned discharged after the head movement onset. These results do not support the idea that the head-pursuit–related modulation reflects head-pursuit commands. Furthermore, modulation similar to that during head-pursuit was obtained by passive head rotation on stationary trunk. Our results suggest that FEF pursuit neurons issue gaze or Eye movement commands during gaze-pursuit and that the head-pursuit–related modulation primarily reflects reafferent signals resulting from head movements.
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Discharge of pursuit-related neurons in the caudal part of the Frontal Eye Fields in juvenile monkeys with up–down pursuit asymmetry
Experimental Brain Research, 2009Co-Authors: Sergei A. Kurkin, Teppei Akao, Junko Fukushima, Kikuro FukushimaAbstract:The smooth-pursuit system uses retinal image-slip-velocity information of target motion to match Eye velocity to actual target velocity. The caudal part of the Frontal Eye Fields (FEF) contains neurons whose activity is related to direction and velocity of smooth-pursuit Eye movements (pursuit neurons), and these neurons are thought to issue a pursuit command. During normal pursuit in well-trained adult monkeys, a pursuit command is usually not differentiable from the actual Eye velocity. We examined whether FEF pursuit neurons signaled the actual Eye velocity during pursuit in juvenile monkeys that exhibited intrinsic differences between upward and downward pursuit capabilities. Two, head-stabilized Japanese monkeys of 4 years of age were tested for sinusoidal vertical pursuit of target motion at 0.2–1.2 Hz (±10°, peak target velocity 12.5–75.0°/s). Gains of downward pursuit were 0.8–0.9 at 0.2–1.0 Hz, and peak downward Eye velocity increased up to ~60°/s linearly with target velocity, whereas peak upward Eye velocity saturated at 15–20°/s. The majority of downward FEF pursuit neurons increased the amplitude of their discharge modulation almost linearly up to 1.2 Hz. The majority of upward FEF pursuit neurons also increased amplitude of modulation nearly linearly as target frequency increased, and the regression slope was similar to that of downward pursuit neurons despite the fact that upward peak Eye velocity saturated at ~0.5 Hz. These results indicate that the responses of the majority of upward FEF pursuit neurons did not signal the actual Eye velocity during pursuit. We suggest that their activity reflected primarily the required Eye velocity.
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Activity of pursuit neurons in the caudal part of the Frontal Eye Fields during static roll-tilt
Experimental Brain Research, 2007Co-Authors: Sergei A. Kurkin, Teppei Akao, Junko Fukushima, Kikuro FukushimaAbstract:The smooth-pursuit system and vestibular system interact to keep the retinal target image on the fovea during head and/or whole body movements. The caudal part of the Frontal Eye Fields (FEF) in the fundus of arcuate sulcus contains pursuit neurons and the majority of them respond to vestibular stimulation induced by whole-body rotation, that activates primarily semi-circular canals, and by whole-body translation, that activates otoliths. To examine whether coordinate frames representing FEF pursuit signals are orbital or earth-vertical, we compared preferred directions during upright and static, whole-body roll-tilt in head- and trunk-restrained monkeys. Preferred directions (re monkeys’ head/trunk axis) of virtually all pursuit neurons tested ( n = 21) were similar during upright and static whole-body roll-tilt. The slight shift of preferred directions of the majority of neurons could be accounted for by ocular counter-rolling. The mean (±SD) differences in preferred directions between upright and 40° right ear down and between upright and 40° left ear down were 6° (±6°) and 5° (±5°), respectively. Visual motion preferred directions were also similar in five pursuit neurons tested. To examine whether FEF pursuit neurons could signal static whole-body roll-tilt, we compared mean discharge rates of 29 neurons during fixation of a stationary spot while upright and during static, whole-body roll-tilt. Virtually all neurons tested (28/29) did not exhibit a significant difference in mean discharge rates between the two conditions. These results suggest that FEF pursuit neurons do not signal static roll-tilt and that they code pursuit signals in head/trunk-centered coordinates.
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role of vestibular signals in the caudal part of the Frontal Eye Fields in pursuit Eye movements in three dimensional space
Annals of the New York Academy of Sciences, 2005Co-Authors: Kikuro Fukushima, Sergei A. Kurkin, Teppei Akao, Junko FukushimaAbstract:: For accurate visual information about objects of interest moving slowly in three-dimensional (3D) space, primates with binocular Fields use both Frontal smooth-pursuit (Frontal-pursuit) and vergence Eye movements (i.e., depth pursuit) to maintain the images of the objects precisely on the foveae of left and right Eyes. Moreover, during head or whole-body movement, both Frontal- and depth-pursuit systems must interact with the vestibular system to minimize slip of the retinal mages that degrades image quality considerably. The caudal part of the Frontal Eye Fields (FEF) contains many Frontal-pursuit neurons. Previous studies have shown that a majority of pursuit neurons there discharge for both Frontal pursuit and vergence and carry pursuit-in-3D signals. To understand how vestibular inputs interact with pursuit-in-3D signals, three different experiments that examined the nature of vestibular signals in the caudal FEF are described in this review. A majority of caudal FEF pursuit neurons responded to whole-body rotation with preferred directions similar to Frontal-pursuit directions and carried Frontal gaze (Eye-in-space) velocity signals. They were activated in association with adaptive pursuit Eye movements induced by cross-axis pursuit-vestibular interactions. During fore/aft and right/left translation in complete darkness, they were also modulated with preferred directions of many neurons similar to pursuit-preferred directions. Previous studies showed that caudal FEF pursuit neurons also receive visual signals about target motion. Taken together, these results suggest that the caudal FEF coordinates its various inputs to provide signals for accurate Eye-movement-in-space commands.
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pursuit related neurons in the supplementary Eye Fields discharge during pursuit and passive whole body rotation
Journal of Neurophysiology, 2004Co-Authors: Junko Fukushima, Teppei Akao, Norihito Takeichi, Sergei Kurkin, Chris R S Kaneko, Kikuro FukushimaAbstract:The primate Frontal cortex contains two areas related to smooth-pursuit: the Frontal Eye Fields (FEFs) and supplementary Eye Fields (SEFs). To distinguish the specific role of the SEFs in pursuit, ...
Richard J. Krauzlis - One of the best experts on this subject based on the ideXlab platform.
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Spatial Attention Deficits Are Causally Linked to an Area in Macaque Temporal Cortex.
Current biology : CB, 2019Co-Authors: Amarender R. Bogadhi, Anil Bollimunta, David A. Leopold, Richard J. KrauzlisAbstract:Spatial neglect is a common clinical syndrome involving disruption of the brain's attention-related circuitry, including the dorsocaudal temporal cortex. In macaques, the attention deficits associated with neglect can be readily modeled, but the absence of evidence for temporal cortex involvement has suggested a fundamental difference from humans. To map the neurological expression of neglect-like attention deficits in macaques, we measured attention-related fMRI activity across the cerebral cortex during experimental induction of neglect through reversible inactivation of the superior colliculus and Frontal Eye Fields. During inactivation, monkeys exhibited hallmark attentional deficits of neglect in tasks using either motion or non-motion stimuli. The behavioral deficits were accompanied by marked reductions in fMRI attentional modulation that were strongest in a small region on the floor of the superior temporal sulcus; smaller reductions were also found in Frontal Eye Fields and dorsal parietal cortex. Notably, direct inactivation of the mid-superior temporal sulcus (STS) cortical region identified by fMRI caused similar neglect-like spatial attention deficits. These results identify a putative macaque homolog to temporal cortex structures known to play a central role in human neglect.
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comparing Frontal Eye field and superior colliculus contributions to covert spatial attention
Nature Communications, 2018Co-Authors: Anil Bollimunta, Amarender R. Bogadhi, Richard J. KrauzlisAbstract:The causal roles of the Frontal Eye Fields (FEF) and superior colliculus (SC) in spatial selective attention have not been directly compared. Reversible inactivation is an established method for testing causality but comparing results between FEF and SC is complicated by differences in size and morphology of the two brain regions. Here we exploited the fact that inactivation of FEF and SC also changes the metrics of saccadic Eye movements, providing an independent benchmark for the strength of the causal manipulation. Using monkeys trained to covertly perform a visual motion-change detection task, we found that inactivation of either FEF or SC could cause deficits in attention task performance. However, SC-induced attention deficits were found with saccade changes half the size needed to get FEF-induced attention deficits. Thus, performance in visual attention tasks is vulnerable to loss of signals from either structure, but suppression of SC activity has a more devastating effect.
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Comparing Frontal Eye field and superior colliculus contributions to covert spatial attention
Nature Publishing Group, 2018Co-Authors: Anil Bollimunta, Amarender R. Bogadhi, Richard J. KrauzlisAbstract:Superior colliculus (SC) and Frontal Eye Fields (FEF) contain visuo-motor maps but their contributions to selective attention are not fully understood. Here, the authors perform reversible inactivations of the SC or FEF and report that loss of SC activity has a more devastating effect on attention
Teppei Akao - One of the best experts on this subject based on the ideXlab platform.
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discharge of pursuit neurons in the caudal part of the Frontal Eye Fields during cross axis vestibular pursuit training in monkeys
Experimental Brain Research, 2009Co-Authors: Keishi Fujiwara, Sergei A. Kurkin, Teppei Akao, Kikuro FukushimaAbstract:Previous studies in monkeys have shown that pursuit training during orthogonal whole body rotation results in task-dependent, predictive pursuit Eye movements. We examined whether pursuit neurons in the Frontal Eye Fields (FEF) are involved in predictive pursuit induced by vestibular-pursuit training. Two monkeys were rotated horizontally at 20°/s for 0.5 s either rightward or leftward with random inter-trial intervals. This chair motion trajectory was synchronized with orthogonal target motion at 20°/s for 0.5 s either upward or downward. Monkeys were rewarded for pursuing the target. Vertical pursuit Eye velocities and discharge of 23 vertical pursuit neurons to vertical target motion were compared before training and during the last 5 min of the 25–45 min training. The latencies of discharge modulation of 61% of the neurons (14/23) shortened after vestibular-pursuit training in association with a shortening of pursuit latency. However, their discharge modulation occurred after 100 ms following the onset of pursuit Eye velocity. Only four neurons (4/23 = 17%) discharged before the Eye movement onset. A significant change was not observed in Eye velocity and FEF pursuit neuron discharge during pursuit alone after training without vestibular stimulation. Vestibular stimulation alone without a target after training induced no clear response. These results suggest that the adaptive change in response to pursuit prediction was induced by vestibular inputs in the presence of target pursuit. FEF pursuit neurons are unlikely to be involved in the initial stage of generating predictive Eye movements. We suggest that they may participate in the maintenance of predictive pursuit.
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Eye pursuit and reafferent head movement signals carried by pursuit neurons in the caudal part of the Frontal Eye Fields during head free pursuit
Cerebral Cortex, 2009Co-Authors: Kikuro Fukushima, Sergei A. Kurkin, Teppei Akao, Junko Fukushima, Satoshi Kasahara, B W PetersonAbstract:Eye and head movements are coordinated during head-free pursuit. To examine whether pursuit neurons in Frontal Eye Fields (FEF) carry gaze-pursuit commands that drive both Eye-pursuit and head-pursuit, monkeys whose heads were free to rotate about a vertical axis were trained to pursue a juice feeder with their head and a target with their Eyes. Initially the feeder and target moved synchronously with the same visual angle. FEF neurons responding to this gaze-pursuit were tested for Eye-pursuit of target motion while the feeder was stationary and for head-pursuit while the target was stationary. The majority of pursuit neurons exhibited modulation during head-pursuit, but their preferred directions during Eye-pursuit and head-pursuit were different. Although peak modulation occurred during head movements, the onset of discharge usually was not aligned with the head movement onset. The minority of neurons whose discharge onset was so aligned discharged after the head movement onset. These results do not support the idea that the head-pursuit–related modulation reflects head-pursuit commands. Furthermore, modulation similar to that during head-pursuit was obtained by passive head rotation on stationary trunk. Our results suggest that FEF pursuit neurons issue gaze or Eye movement commands during gaze-pursuit and that the head-pursuit–related modulation primarily reflects reafferent signals resulting from head movements.
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Discharge of pursuit-related neurons in the caudal part of the Frontal Eye Fields in juvenile monkeys with up–down pursuit asymmetry
Experimental Brain Research, 2009Co-Authors: Sergei A. Kurkin, Teppei Akao, Junko Fukushima, Kikuro FukushimaAbstract:The smooth-pursuit system uses retinal image-slip-velocity information of target motion to match Eye velocity to actual target velocity. The caudal part of the Frontal Eye Fields (FEF) contains neurons whose activity is related to direction and velocity of smooth-pursuit Eye movements (pursuit neurons), and these neurons are thought to issue a pursuit command. During normal pursuit in well-trained adult monkeys, a pursuit command is usually not differentiable from the actual Eye velocity. We examined whether FEF pursuit neurons signaled the actual Eye velocity during pursuit in juvenile monkeys that exhibited intrinsic differences between upward and downward pursuit capabilities. Two, head-stabilized Japanese monkeys of 4 years of age were tested for sinusoidal vertical pursuit of target motion at 0.2–1.2 Hz (±10°, peak target velocity 12.5–75.0°/s). Gains of downward pursuit were 0.8–0.9 at 0.2–1.0 Hz, and peak downward Eye velocity increased up to ~60°/s linearly with target velocity, whereas peak upward Eye velocity saturated at 15–20°/s. The majority of downward FEF pursuit neurons increased the amplitude of their discharge modulation almost linearly up to 1.2 Hz. The majority of upward FEF pursuit neurons also increased amplitude of modulation nearly linearly as target frequency increased, and the regression slope was similar to that of downward pursuit neurons despite the fact that upward peak Eye velocity saturated at ~0.5 Hz. These results indicate that the responses of the majority of upward FEF pursuit neurons did not signal the actual Eye velocity during pursuit. We suggest that their activity reflected primarily the required Eye velocity.
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Activity of pursuit neurons in the caudal part of the Frontal Eye Fields during static roll-tilt
Experimental Brain Research, 2007Co-Authors: Sergei A. Kurkin, Teppei Akao, Junko Fukushima, Kikuro FukushimaAbstract:The smooth-pursuit system and vestibular system interact to keep the retinal target image on the fovea during head and/or whole body movements. The caudal part of the Frontal Eye Fields (FEF) in the fundus of arcuate sulcus contains pursuit neurons and the majority of them respond to vestibular stimulation induced by whole-body rotation, that activates primarily semi-circular canals, and by whole-body translation, that activates otoliths. To examine whether coordinate frames representing FEF pursuit signals are orbital or earth-vertical, we compared preferred directions during upright and static, whole-body roll-tilt in head- and trunk-restrained monkeys. Preferred directions (re monkeys’ head/trunk axis) of virtually all pursuit neurons tested ( n = 21) were similar during upright and static whole-body roll-tilt. The slight shift of preferred directions of the majority of neurons could be accounted for by ocular counter-rolling. The mean (±SD) differences in preferred directions between upright and 40° right ear down and between upright and 40° left ear down were 6° (±6°) and 5° (±5°), respectively. Visual motion preferred directions were also similar in five pursuit neurons tested. To examine whether FEF pursuit neurons could signal static whole-body roll-tilt, we compared mean discharge rates of 29 neurons during fixation of a stationary spot while upright and during static, whole-body roll-tilt. Virtually all neurons tested (28/29) did not exhibit a significant difference in mean discharge rates between the two conditions. These results suggest that FEF pursuit neurons do not signal static roll-tilt and that they code pursuit signals in head/trunk-centered coordinates.
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role of vestibular signals in the caudal part of the Frontal Eye Fields in pursuit Eye movements in three dimensional space
Annals of the New York Academy of Sciences, 2005Co-Authors: Kikuro Fukushima, Sergei A. Kurkin, Teppei Akao, Junko FukushimaAbstract:: For accurate visual information about objects of interest moving slowly in three-dimensional (3D) space, primates with binocular Fields use both Frontal smooth-pursuit (Frontal-pursuit) and vergence Eye movements (i.e., depth pursuit) to maintain the images of the objects precisely on the foveae of left and right Eyes. Moreover, during head or whole-body movement, both Frontal- and depth-pursuit systems must interact with the vestibular system to minimize slip of the retinal mages that degrades image quality considerably. The caudal part of the Frontal Eye Fields (FEF) contains many Frontal-pursuit neurons. Previous studies have shown that a majority of pursuit neurons there discharge for both Frontal pursuit and vergence and carry pursuit-in-3D signals. To understand how vestibular inputs interact with pursuit-in-3D signals, three different experiments that examined the nature of vestibular signals in the caudal FEF are described in this review. A majority of caudal FEF pursuit neurons responded to whole-body rotation with preferred directions similar to Frontal-pursuit directions and carried Frontal gaze (Eye-in-space) velocity signals. They were activated in association with adaptive pursuit Eye movements induced by cross-axis pursuit-vestibular interactions. During fore/aft and right/left translation in complete darkness, they were also modulated with preferred directions of many neurons similar to pursuit-preferred directions. Previous studies showed that caudal FEF pursuit neurons also receive visual signals about target motion. Taken together, these results suggest that the caudal FEF coordinates its various inputs to provide signals for accurate Eye-movement-in-space commands.
