The Experts below are selected from a list of 390 Experts worldwide ranked by ideXlab platform
Klauspeter Hoffmann - One of the best experts on this subject based on the ideXlab platform.
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Sensitivity of the Goldfish Motion Detection System Revealed by Incoherent Random Dot Stimuli: Comparison of Behavioural and Neuronal Data
2009Co-Authors: Olivia Andrea Masseck, Sascha Förster, Klauspeter HoffmannAbstract:Background: Global motion detection is one of the most important abilities in the animal kingdom to navigate through a 3-dimensional environment. In the visual system of teleost fish direction-selective neurons in the Pretectal Area (APT) are most important for global motion detection. As in all other vertebrates these neurons are involved in the control of slow phase eye movements during gaze stabilization. In contrast to mammals cortical pathways that might influence motion detection abilities of the optokinetic system are missing in teleost fish. Results: To test global motion detection in goldfish we first measured the coherence threshold of random dot patterns to elicit horizontal slow phase eye movements. In addition, the coherence threshold of the optomotor response was determined by the same random dot patterns. In a second approach the coherence threshold to elicit a direction selective response in neurons of the APT was assessed from a neurometric function. Behavioural thresholds and neuronal thresholds to elicit slow phase eye movements were very similar, and ranged between 10 % and 20 % coherence. In contrast to these low thresholds for the optokinetic reaction and APT neurons the optomotor response could only be elicited by random dot patterns with coherences above 40%. Conclusion: Our findings suggest a high sensitivity for global motion in the goldfish optokinetic system. Comparison of neuronal and behavioural thresholds implies a nearly one-to-one transformation of visual neuron performance to the visuomoto
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responses to moving visual stimuli in Pretectal neurons of the small spotted dogfish scyliorhinus canicula
Journal of Neurophysiology, 2008Co-Authors: Olivia Andrea Masseck, Klauspeter HoffmannAbstract:Single-unit recordings were performed from a retinorecipient Pretectal Area (corpus geniculatum laterale) in Scyliorhinus canicula. The function and homology of this nucleus has not been clarified so far. During visual stimulation with a random dot pattern, 45 (35%) neurons were found to be direction selective, 10 (8%) were axis selective (best neuronal responses to rotations in both directions around one particular stimulus axis), and 75 (58%) were movement sensitive. Direction-selective responses were found to the following stimulus directions (in retinal coordinates): temporonasal and nasotemporal horizontal movements, up- and downward vertical movements, and oblique movements. All directions of motion were represented equally by our sample of Pretectal neurons. Additionally we tested the responses of 58 of the 130 neurons to random dot patterns rotating around the semicircular canal or body axes to investigate whether direction-selective visual information is mapped into vestibular coordinates in pret...
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Sensitivity of the goldfish motion detection system revealed by incoherent random dot stimuli: comparison of behavioural and neuronal data.
Public Library of Science (PLoS), 2026Co-Authors: Olivia Andrea Masseck, Sascha Förster, Klauspeter HoffmannAbstract:BACKGROUND: Global motion detection is one of the most important abilities in the animal kingdom to navigate through a 3-dimensional environment. In the visual system of teleost fish direction-selective neurons in the Pretectal Area (APT) are most important for global motion detection. As in all other vertebrates these neurons are involved in the control of slow phase eye movements during gaze stabilization. In contrast to mammals cortical pathways that might influence motion detection abilities of the optokinetic system are missing in teleost fish. RESULTS: To test global motion detection in goldfish we first measured the coherence threshold of random dot patterns to elicit horizontal slow phase eye movements. In addition, the coherence threshold of the optomotor response was determined by the same random dot patterns. In a second approach the coherence threshold to elicit a direction selective response in neurons of the APT was assessed from a neurometric function. Behavioural thresholds and neuronal thresholds to elicit slow phase eye movements were very similar, and ranged between 10% and 20% coherence. In contrast to these low thresholds for the optokinetic reaction and APT neurons the optomotor response could only be elicited by random dot patterns with coherences above 40%. CONCLUSION: Our findings suggest a high sensitivity for global motion in the goldfish optokinetic system. Comparison of neuronal and behavioural thresholds implies a nearly one-to-one transformation of visual neuron performance to the visuo-motor output. In addition, we assume that the optomotor response is not mediated by the optokinetic system, but instead by other motion detection systems with higher coherence thresholds
Olivia Andrea Masseck - One of the best experts on this subject based on the ideXlab platform.
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Sensitivity of the Goldfish Motion Detection System Revealed by Incoherent Random Dot Stimuli: Comparison of Behavioural and Neuronal Data
2009Co-Authors: Olivia Andrea Masseck, Sascha Förster, Klauspeter HoffmannAbstract:Background: Global motion detection is one of the most important abilities in the animal kingdom to navigate through a 3-dimensional environment. In the visual system of teleost fish direction-selective neurons in the Pretectal Area (APT) are most important for global motion detection. As in all other vertebrates these neurons are involved in the control of slow phase eye movements during gaze stabilization. In contrast to mammals cortical pathways that might influence motion detection abilities of the optokinetic system are missing in teleost fish. Results: To test global motion detection in goldfish we first measured the coherence threshold of random dot patterns to elicit horizontal slow phase eye movements. In addition, the coherence threshold of the optomotor response was determined by the same random dot patterns. In a second approach the coherence threshold to elicit a direction selective response in neurons of the APT was assessed from a neurometric function. Behavioural thresholds and neuronal thresholds to elicit slow phase eye movements were very similar, and ranged between 10 % and 20 % coherence. In contrast to these low thresholds for the optokinetic reaction and APT neurons the optomotor response could only be elicited by random dot patterns with coherences above 40%. Conclusion: Our findings suggest a high sensitivity for global motion in the goldfish optokinetic system. Comparison of neuronal and behavioural thresholds implies a nearly one-to-one transformation of visual neuron performance to the visuomoto
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responses to moving visual stimuli in Pretectal neurons of the small spotted dogfish scyliorhinus canicula
Journal of Neurophysiology, 2008Co-Authors: Olivia Andrea Masseck, Klauspeter HoffmannAbstract:Single-unit recordings were performed from a retinorecipient Pretectal Area (corpus geniculatum laterale) in Scyliorhinus canicula. The function and homology of this nucleus has not been clarified so far. During visual stimulation with a random dot pattern, 45 (35%) neurons were found to be direction selective, 10 (8%) were axis selective (best neuronal responses to rotations in both directions around one particular stimulus axis), and 75 (58%) were movement sensitive. Direction-selective responses were found to the following stimulus directions (in retinal coordinates): temporonasal and nasotemporal horizontal movements, up- and downward vertical movements, and oblique movements. All directions of motion were represented equally by our sample of Pretectal neurons. Additionally we tested the responses of 58 of the 130 neurons to random dot patterns rotating around the semicircular canal or body axes to investigate whether direction-selective visual information is mapped into vestibular coordinates in pret...
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Sensitivity of the goldfish motion detection system revealed by incoherent random dot stimuli: comparison of behavioural and neuronal data.
Public Library of Science (PLoS), 2026Co-Authors: Olivia Andrea Masseck, Sascha Förster, Klauspeter HoffmannAbstract:BACKGROUND: Global motion detection is one of the most important abilities in the animal kingdom to navigate through a 3-dimensional environment. In the visual system of teleost fish direction-selective neurons in the Pretectal Area (APT) are most important for global motion detection. As in all other vertebrates these neurons are involved in the control of slow phase eye movements during gaze stabilization. In contrast to mammals cortical pathways that might influence motion detection abilities of the optokinetic system are missing in teleost fish. RESULTS: To test global motion detection in goldfish we first measured the coherence threshold of random dot patterns to elicit horizontal slow phase eye movements. In addition, the coherence threshold of the optomotor response was determined by the same random dot patterns. In a second approach the coherence threshold to elicit a direction selective response in neurons of the APT was assessed from a neurometric function. Behavioural thresholds and neuronal thresholds to elicit slow phase eye movements were very similar, and ranged between 10% and 20% coherence. In contrast to these low thresholds for the optokinetic reaction and APT neurons the optomotor response could only be elicited by random dot patterns with coherences above 40%. CONCLUSION: Our findings suggest a high sensitivity for global motion in the goldfish optokinetic system. Comparison of neuronal and behavioural thresholds implies a nearly one-to-one transformation of visual neuron performance to the visuo-motor output. In addition, we assume that the optomotor response is not mediated by the optokinetic system, but instead by other motion detection systems with higher coherence thresholds
Jon H. Kaas - One of the best experts on this subject based on the ideXlab platform.
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frontal eye field in prosimian galagos intracortical microstimulation and tracing studies
The Journal of Comparative Neurology, 2018Co-Authors: Iwona Stepniewska, Pierre Pouget, Jon H. KaasAbstract:The frontal eye field (FEF) in prosimian primates was identified as a small cortical region, above and anterior to the anterior frontal sulcus, from which saccadic eye movements were evoked with electrical stimulation. Tracer injections revealed FEF connections with cortical and subcortical structures participating in higher order visual processing. Ipsilateral cortical connections were the densest with adjoining parts of the dorsal premotor and prefrontal cortex (PFC). Label in a region corresponding to supplementary eye field (SEF) of other primates, suggests the existence of SEF in galagos. Other connections were with ventral premotor cortex (PMV), the caudal half of posterior parietal cortex, cingulate cortex, visual Areas within the superior temporal sulcus, and inferotemporal cortex. Callosal connections were mostly with the region of the FEF of another hemisphere, SEF, PFC and PMV. Most subcortical connections were ipsilateral, but some were bilateral. Dense bilateral connections were to caudate nuclei. Densest reciprocal ipsilateral connections were with the paralamellar portion of mediodorsal nucleus, intralaminar nuclei and magnocellular portion of ventral anterior nucleus. Other FEF connections were with the claustrum, reticular nucleus, zona incerta, lateral posterior and medial pulvinar nuclei, nucleus limitans, Pretectal Area, nucleus of Darkschewitsch, mesencephalic and pontine reticular formation and pontine nuclei. Surprisingly, the superior colliculus (SC) contained only sparse anterograde label. Although most FEF connections in galagos are similar to those in monkeys, the FEF-SC connections appear to be much less. This suggests that a major contribution of the FEF to visuomotor functions of SC emerged with the evolution of anthropoid primates. This article is protected by copyright. All rights reserved.
Tudor C Badea - One of the best experts on this subject based on the ideXlab platform.
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characterization of retinal ganglion cell horizontal cell and amacrine cell types expressing the neurotrophic receptor tyrosine kinase ret
The Journal of Comparative Neurology, 2018Co-Authors: Nadia Parmhans, Szilard Sajgo, Jingwen Niu, Wenqin Luo, Tudor C BadeaAbstract:We report the retinal expression pattern of Ret, a receptor tyrosine kinase for the glial derived neurotrophic factor (GDNF) family ligands (GFLs), during development and in the adult mouse. Ret is initially expressed in retinal ganglion cells (RGCs), followed by horizontal cells (HCs) and amacrine cells (ACs), beginning with the early stages of postmitotic development. Ret expression persists in all three classes of neurons in the adult. Using RNA sequencing, immunostaining and random sparse recombination, we show that Ret is expressed in at least three distinct types of ACs, and ten types of RGCs. Using intersectional genetics, we describe the dendritic arbor morphologies of RGC types expressing Ret in combination with each of the three members of the POU4f/Brn3 family of transcription factors. Ret expression overlaps with Brn3a in 4 RGC types, with Brn3b in 5 RGC types, and with Brn3c in one RGC type, respectively. Ret+ RGCs project to the lateral geniculate nucleus (LGN), Pretectal Area (PTA) and superior colliculus (SC), and avoid the suprachiasmatic nucleus and accessory optic system. Brn3a+ Ret+ and Brn3c+ Ret+ RGCs project preferentially to contralateral retinorecipient Areas, while Brn3b+ Ret+ RGCs shows minor ipsilateral projections to the olivary Pretectal nucleus and the LGN. Our findings establish intersectional genetic approaches for the anatomic and developmental characterization of individual Ret+ RGC types. In addition, they provide necessary information for addressing the potential interplay between GDNF neurotrophic signaling and transcriptional regulation in RGC type specification.
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RGC axon projections to retinorecipient Areas of the brain are differentially affected by loss of pairwise combinations of two Brn3 transcription factors.
2013Co-Authors: Melody Shi, Sumit R. Kumar, Oluwaseyi Motajo, Friedrich Kretschmer, Tudor C BadeaAbstract:Columns A–L represent coronal sections through the brains of mice with identical genotypes to the ones presented in Figure 1 A–L. For each genotype, trajectories of Brn3AP RGCs through five distinct stations of the optic nerve and tract are shown: (i) optic chiasm (oc) and Suprachiasmatic Nucleus (SCN), (ii) optic tract (ot), ventral Lateral Geniculate Nucleus (vLGN), Intergeniculate Leaflet (IGL), dorsal Lateral Geniculate Nucleus (dLGN), optic brachium (ob), Olivary Pretectal Nucleus (OPN), (iii) Caudal Pretectal Area (PA), Dorsal Terminal Nucleus (DTN), and Lateral Terminal Nucleus (LTN), (iv) Medial Terminal Nucleus (MTN), and (v) Superior Colliculus (SC). Nuclei are in capital letters, and axon tracts are in lower case. Consistent with RGC losses in the retina, only combined loss of Brn3a and Brn3b results in a complete removal of RGC axons from all portions of the optic path and retinorecipient nuclei (A–D). A'– D', Ventral views of unstained whole mouse brains with same genotypes as A–D. Note the reductions in optic nerve (green arrow) diameters and thickness and position of the optic chiasm (blue arrow) in Brn3b KO (C') and Brn3a-Brn3b DKO (D') mice. Brn3cAP RGC projections to all targets (dLGN and SC) are equally reduced in the absence of Brn3b (G) or combined deletion of Brn3b and Brn3c (H). Similar data were obtained from all mice of all genotypes as described all in Fig. 2. Scale bar in L = 1 mm.
Guandalini P. - One of the best experts on this subject based on the ideXlab platform.
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The efferent connections of the pupillary constriction Area in the rat medial frontal cortex
2003Co-Authors: Guandalini P.Abstract:This study investigated, in the rat, the efferent projections of the pupillary constriction Area, which is located within the medial frontal cortex. In order to identify the location of the pupillary constriction Area, in preliminary experiments the medial frontal cortex was microstimulated. Intracortical microstimulation elicited pupillary constriction in a thin strip of cortex the interhemispheric fissure and bordering the frontal eye field and vibrissae Area of the somatomotor cortex. Seven animals received a single iontophoretic injection of Phaseolus vulgaris leucoagglutinin in the pupillary constriction Area. In these cases, anterogradely labelled fibres and terminal-like elements were found in both hemispheres. The densest labeling was seen in several Areas of the injected hemisphere, were labeled fibers prevailed in the secondary visual cortex. Dense labeled fibers were also found in the retrosplenial and cingulate cortex. In the thalamus, labeled fibers were seen in the intralaminar nuclei and posterior nuclear group. In the midbrain and pons, labeled fibers were located in the anterior Pretectal Area, superior colliculus and in the dorsolateral portion of the central gray. Contralaterally to the injection site, labeled fibers were distributed in the homotopic region. These findings led us to assume that, in the medial frontal cortex of the rat, besides controlling pupillary constriction, the pupillary constriction Area may also be involved in controlling orientation and exploring behavior
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The efferent connections to the thalamus and brainstem of the physiologically defined eye field in rat medial frontal cortex.
2001Co-Authors: Guandalini P.Abstract:The anterograde tracer Phaseolus vulgaris leucoagglutinin (PHA-L) was injected into sites of the rat frontal eye field (FEF) located in the medial frontal cortex. After a single iontophoret injection of PHA-L into a FEF site where intracortical microstimulation elicited eye movements, anteogradely labelled fibres and terminal-like elements found in the thalamus in the anterior nuclei, intralaminar nuclei, lateral portion of the mediodorsal nucleus and posterior nuclear group. In the midbrain and pons, labelled fibres were located in the anterior Pretectal Area, Darkschewitsch nucleus, superior colliculus and dorsolateral portion of the central gray. When the tracer was injected at the FEF periphery, at a site the stimulation of which evoked both eye and whisker movements, labelling distribution in the thalamus differed from that observed after FEF injections, while a similar distribution was observed in the brainstem. In the thalamus, anterograde labelling was observed in these latter cases in the anterior nuclei, ventral nuclei, medial portion of the laterodorsal nucleus. The present findings point out that the FEF and FEF periphery are connected with numerous subcortical structures of the thalamus and brainstem. In addition, the connections of FEF and FEF periphery with the thalamus differ, whereas the midbrain and pons connections of the two subdivisions share common targets