The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Robijanto Soetedjo - One of the best experts on this subject based on the ideXlab platform.
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elimination of the Error Signal in the superior colliculus impairs saccade motor learning
Proceedings of the National Academy of Sciences of the United States of America, 2018Co-Authors: Yoshiko Kojima, Robijanto SoetedjoAbstract:When movements become dysmetric, the resultant motor Error induces a plastic change in the cerebellum to correct the movement, i.e., motor adaptation. Current evidence suggests that the Error Signal to the cerebellum is delivered by complex spikes originating in the inferior olive (IO). To prove a causal link between the IO Error Signal and motor adaptation, several studies blocked the IO, which, unfortunately, affected not only the adaptation but also the movement itself. We avoided this confound by inactivating the source of an Error Signal to the IO. Several studies implicate the superior colliculus (SC) as the source of the Error Signal to the IO for saccade adaptation. When we inactivated the SC, the metrics of the saccade to be adapted were unchanged, but saccade adaptation was impaired. Thus, an intact rostral SC is necessary for saccade adaptation. Our data provide experimental evidence for the cerebellar learning theory that requires an Error Signal to drive motor adaptation.
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evidence that the superior colliculus participates in the feedback control of saccadic eye movements
Journal of Neurophysiology, 2002Co-Authors: Robijanto Soetedjo, Chris R S Kaneko, Albert F FuchsAbstract:There is general agreement that saccades are guided to their targets by means of a motor Error Signal, which is produced by a local feedback circuit that calculates the difference between desired s...
István Czigler - One of the best experts on this subject based on the ideXlab platform.
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visual mismatch negativity vmmn a prediction Error Signal in the visual modality
Frontiers in Human Neuroscience, 2015Co-Authors: Gábor Stefanics, Piia Astikainen, István CziglerAbstract:Our visual field contains much more information at everymoment than we can attend and consciously process. How isthe multitude of unattended events processed in the brain andselected for the further attentive evaluation? Current theories ofvisual change detection emphasize the importance of consciousattention to detect changes in the visual environment. However,an increasing body of studies shows that the human brain iscapable of detecting even small visual changes if such changesviolate non-conscious probabilistic expectations based on priorexperiences. In other words, our brain automatically representsenvironmental statistical regularities.Since the discovery of the auditory mismatch negativity(MMN) event-related potential (ERP) component, the majorityof research in the field has focused on auditory deviance detec-tion.Suchautomaticchangedetectionmechanismsoperateinthevisual modality too, as indicated by the visual mismatch negativ-ity (vMMN) brain potential to rare changes. vMMN is typicallyelicited by stimuli with infrequent (deviant) features embeddedin a stream of frequent (standard) stimuli, outside the focus ofattention. Information about both simple and more complexcharacteristics of stimuli is rapidly processed and stored by thebrain in the absence of conscious attention.InthisresearchtopicweaimtopresentvMMNasapredictionError Signal and put it in context of the hierarchical predictivecoding framework. Predictive coding theories account for phe-nomena such as MMN and repetition suppression, and placetheminabroadercontextofageneraltheoryofcorticalresponses(Friston,2005,2010).EachpaperinthisResearchTopicisavalu-able contribution to the field of automatic visual change detec-tion and deepens our understanding of the short term plasticityunderlying predictive processes of visual perceptual learning.A wide range of vMMN studies has been presented in sev-enteen articles in this Research Topic. Twelve articles addressroughly four general sub-themes including attention, language,faceprocessing,andpsychiatricdisorders.Additionally,fourarti-cles focused on particular subjects such as the oblique effect,object formation, and development and time-frequency analysisof vMMN. Furthermore, a review paper presented vMMN in ahierarchical predictive coding framework.Four articles investigated the relationship between attentionand vMMN. Kremlaˇcek et al. (2013) presented subjects withradial motion stimuli in the periphery of the visual field usingan oddball paradigm and manipulated the attentional load byvarying the difficulty of a central distractor tasks. They aimedto manipulate the amount of available attentional resources thatmight have been involuntarily captured by the vMMN-evokingstimulipresentedintheperipheryoutsideoftheattentionalfocus.The distractor task had three difficulty levels: (1) a central fix-ation (easy), and a target number detection task with (2) onetarget number (moderate), and (3) three target numbers (diffi-cult). Analysis of deviant minus standard differential waveformsrevealed a significant posterior negativity in the ∼140–200msinterval,whichwasunaffectedbythedifficultyofthecentraltask,indicatingthattheautomaticprocessesunderlyingregistrationofchanges in motion are independent of attentional resources usedto detect target numbers.Kimura and Takeda (2013) investigated whether characteris-tics of vMMN depended on the difficulty of an attended primarytask, i.e., they tested the level of automaticity of the vMMN. Taskdifficulty was manipulated as the magnitude of change of a cir-cle at fixation, and vMMN was elicited by deviant orientationof bar patterns. An equal probability control condition was alsoused. The difference potential between the deviant-related ERPand the ERP elicited by identical orientation pattern in the con-trol condition appeared to be influenced by the difficulty of theattentive task. As a function of task difficulty, the latency of thedifference potential (i.e., the vMMN) increased, indicating thatprocesses underlying vMMN to orientation changes are not fullyindependent of the attention demands of the ongoing tasks.Kuldkepp et al. (2013) used rare changes in direction ofperipheral motion to evoke vMMN applying a novel continuouswhole-display stimulus configuration. The demanding distractortask involved motion onset detection and was presented in thecenter of the visual field. The level of attention to the vMMN-evoking stimuli was varied by manipulating their task-relevanceusing “Ignore” and “Attend” conditions. Deviant minus standardwaveforms in the “Ignore” condition showed significant vMMNin the 100–200, 250–300, and 235–375ms intervals, whereas in
So Chloe - One of the best experts on this subject based on the ideXlab platform.
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Zeeman-tunable Modulation Transfer Spectroscopy
2020Co-Authors: So ChloeAbstract:Active frequency stabilization of a laser to an atomic or molecular resonance underpins many modern-day AMO physics experiments. With a flat background and high Signal-to-noise ratio, modulation transfer spectroscopy (MTS) offers an accurate and stable method for laser locking. Despite its benefits, however, the four-wave mixing process that is inherent to the MTS technique entails that the strongest modulation transfer Signals are only observed for closed transitions, excluding MTS from numerous applications. Here, we report for the first time the observation of a magnetically tunable MTS Error Signal. Using a simple two-magnet arrangement, we show that the Error Signal for the 87Rb F = 2 → F' = 3 cooling transition can be Zeeman-shifted over a range of ~10 GHz to any arbitrary point on the rubidium D2 spectrum. Modulation transfer Signals for locking to the 87Rb F = 1 → F' = 2 repumping transition as well as 1 GHz red-detuned to the cooling transition are presented to demonstrate the versatility of this technique, which can readily be extended to the locking of Raman and lattice lasers
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Zeeman-tunable modulation transfer spectroscopy.
'The Optical Society', 2019Co-Authors: So Chloe, Spong, Nicholas L. R., Möhl Charles, Jiao Yuechun, Ilieva Teodora, Adams, Charles S.Abstract:Active frequency stabilization of a laser to an atomic or molecular resonance underpins many modern-day AMO physics experiments. With a flat background and high Signal-to-noise ratio, modulation transfer spectroscopy (MTS) offers an accurate and stable method for laser locking. However, despite its benefits, the four-wave mixing process that is inherent to the MTS technique entails that the strongest modulation transfer Signals are only observed for closed transitions, excluding MTS from numerous applications. Here we report for the first time, to the best of our knowledge, the observation of a magnetically tunable MTS Error Signal. Using a simple two-magnet arrangement, we show that the Error Signal for the Rb87 ????=2→????′=3 cooling transition can be Zeeman-shifted over a range of >15 GHzto any arbitrary point on the rubidium D2 spectrum. Modulation transfer Signals for locking to the Rb87 ????=1→????′=2 repumping transition, as well as 1 GHz red-detuned to the cooling transition, are presented to demonstrate the versatility of this technique, which can readily be extended to the locking of Raman and lattice lasers
M Shuker - One of the best experts on this subject based on the ideXlab platform.
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reduction of light shifts in ramsey spectroscopy with a combined Error Signal
Applied Physics Letters, 2019Co-Authors: M Shuker, J W Pollock, Rodolphe Boudot, V I Yudin, A V Taichenachev, John KitchingAbstract:Light-induced frequency shifts can be a key limiting contribution to the mid- and long-term frequency instabilities in atomic clocks. In this letter, we demonstrate the experimental implementation of the combined Error Signal interrogation protocol to a cold-atom clock based on coherent population trapping (CPT) and Ramsey spectroscopy. The method uses a single Error Signal that results from the normalized combination of two Error Signals extracted from two Ramsey sequences of different dark periods. The single combined Error Signal is used to stabilize the atomic clock frequency. Compared to the standard Ramsey-CPT interrogation, this method reduces the clock frequency sensitivity to light-shift variations by more than one order of magnitude. This method can be applied in various kinds of Ramsey-based atomic clocks, sensors, and instruments.Light-induced frequency shifts can be a key limiting contribution to the mid- and long-term frequency instabilities in atomic clocks. In this letter, we demonstrate the experimental implementation of the combined Error Signal interrogation protocol to a cold-atom clock based on coherent population trapping (CPT) and Ramsey spectroscopy. The method uses a single Error Signal that results from the normalized combination of two Error Signals extracted from two Ramsey sequences of different dark periods. The single combined Error Signal is used to stabilize the atomic clock frequency. Compared to the standard Ramsey-CPT interrogation, this method reduces the clock frequency sensitivity to light-shift variations by more than one order of magnitude. This method can be applied in various kinds of Ramsey-based atomic clocks, sensors, and instruments.
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reduction of light shifts in ramsey spectroscopy with a combined Error Signal
arXiv: Atomic Physics, 2019Co-Authors: M Shuker, J W Pollock, Rodolphe Boudot, V I Yudin, A V Taichenachev, John KitchingAbstract:Light-induced frequency shifts can be a key limiting contribution to the mid and long-term frequency instability in atomic clocks. In this letter, we demonstrate the experimental implementation of the combined Error Signal interrogation protocol to a cold-atom clock based on coherent population trapping (CPT) and Ramsey spectroscopy. The method uses a single Error Signal that results from the normalized combination of two Error Signals extracted from two Ramsey sequences of different dark periods. The single combined Error Signal is used to stabilize the atomic clock frequency. Compared to the standard Ramsey-CPT interrogation, this method reduces the clock frequency sensitivity to light-shift variations by more than one order of magnitude. This method can be applied in various kinds of Ramsey-based atomic clocks, sensors and instruments.
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Reduction of light shifts in Ramsey spectroscopy with a combined Error Signal
Applied Physics Letters, 2019Co-Authors: M Shuker, Rodolphe Boudot, A V Taichenachev, John Kitching, J Pollock, Valeriy Yudin, E DonleyAbstract:Light-induced frequency shifts can be a key limiting contribution to the mid- and long-term frequency instabilities in atomic clocks. In this letter, we demonstrate the experimental implementation of the combined Error Signal interrogation protocol to a cold-atom clock based on coherent population trapping (CPT) and Ramsey spectroscopy. The method uses a single Error Signal that results from the normalized combination of two Error Signals extracted from two Ramsey sequences of different dark periods. The single combined Error Signal is used to stabilize the atomic clock frequency. Compared to the standard Ramsey-CPT interrogation, this method reduces the clock frequency sensitivity to light-shift variations by more than one order of magnitude. This method can be applied in various kinds of Ramsey-based atomic clocks, sensors, and instruments.
John Kitching - One of the best experts on this subject based on the ideXlab platform.
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reduction of light shifts in ramsey spectroscopy with a combined Error Signal
Applied Physics Letters, 2019Co-Authors: M Shuker, J W Pollock, Rodolphe Boudot, V I Yudin, A V Taichenachev, John KitchingAbstract:Light-induced frequency shifts can be a key limiting contribution to the mid- and long-term frequency instabilities in atomic clocks. In this letter, we demonstrate the experimental implementation of the combined Error Signal interrogation protocol to a cold-atom clock based on coherent population trapping (CPT) and Ramsey spectroscopy. The method uses a single Error Signal that results from the normalized combination of two Error Signals extracted from two Ramsey sequences of different dark periods. The single combined Error Signal is used to stabilize the atomic clock frequency. Compared to the standard Ramsey-CPT interrogation, this method reduces the clock frequency sensitivity to light-shift variations by more than one order of magnitude. This method can be applied in various kinds of Ramsey-based atomic clocks, sensors, and instruments.Light-induced frequency shifts can be a key limiting contribution to the mid- and long-term frequency instabilities in atomic clocks. In this letter, we demonstrate the experimental implementation of the combined Error Signal interrogation protocol to a cold-atom clock based on coherent population trapping (CPT) and Ramsey spectroscopy. The method uses a single Error Signal that results from the normalized combination of two Error Signals extracted from two Ramsey sequences of different dark periods. The single combined Error Signal is used to stabilize the atomic clock frequency. Compared to the standard Ramsey-CPT interrogation, this method reduces the clock frequency sensitivity to light-shift variations by more than one order of magnitude. This method can be applied in various kinds of Ramsey-based atomic clocks, sensors, and instruments.
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reduction of light shifts in ramsey spectroscopy with a combined Error Signal
arXiv: Atomic Physics, 2019Co-Authors: M Shuker, J W Pollock, Rodolphe Boudot, V I Yudin, A V Taichenachev, John KitchingAbstract:Light-induced frequency shifts can be a key limiting contribution to the mid and long-term frequency instability in atomic clocks. In this letter, we demonstrate the experimental implementation of the combined Error Signal interrogation protocol to a cold-atom clock based on coherent population trapping (CPT) and Ramsey spectroscopy. The method uses a single Error Signal that results from the normalized combination of two Error Signals extracted from two Ramsey sequences of different dark periods. The single combined Error Signal is used to stabilize the atomic clock frequency. Compared to the standard Ramsey-CPT interrogation, this method reduces the clock frequency sensitivity to light-shift variations by more than one order of magnitude. This method can be applied in various kinds of Ramsey-based atomic clocks, sensors and instruments.
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Reduction of light shifts in Ramsey spectroscopy with a combined Error Signal
Applied Physics Letters, 2019Co-Authors: M Shuker, Rodolphe Boudot, A V Taichenachev, John Kitching, J Pollock, Valeriy Yudin, E DonleyAbstract:Light-induced frequency shifts can be a key limiting contribution to the mid- and long-term frequency instabilities in atomic clocks. In this letter, we demonstrate the experimental implementation of the combined Error Signal interrogation protocol to a cold-atom clock based on coherent population trapping (CPT) and Ramsey spectroscopy. The method uses a single Error Signal that results from the normalized combination of two Error Signals extracted from two Ramsey sequences of different dark periods. The single combined Error Signal is used to stabilize the atomic clock frequency. Compared to the standard Ramsey-CPT interrogation, this method reduces the clock frequency sensitivity to light-shift variations by more than one order of magnitude. This method can be applied in various kinds of Ramsey-based atomic clocks, sensors, and instruments.