Visuelle Funktionen des Superior Colliculus beim Primaten
Zusammenfassung der Projektergebnisse
Foveal vision affords us the ability to recognize complex objects, but successfully orienting the fovea to the object of interest in the first place is equally important. Investigations of object recognition have overwhelmingly focused on foveal vision, thereby, ignoring the mechanisms behind peripheral object detection that facilitate foveal orienting. In this project, we filled this important gap through novel investigations of an evolutionarily conserved brain structure, the midbrain superior colliculus (SC), which can contribute simultaneously to both peripheral object detection and orienting of the fovea for detailed object processing. In primates, despite diverse inputs from both retina and visual cortex, our understanding of the SC’s visual functions has remained to be poor. We hypothesized that the SC facilitates peripheral object detection through visual selection mechanisms, thereby, bridging the dichotomy between visual object recognition at the fovea, on the one hand, and visual orienting towards peripheral objects, on the other. We characterized SC visual functions, particularly in the context of visual object processing, and we highlighted the underestimated role that this structure can play in object detection. We specifically investigated global form-based object detection as well as the relevance of low spatial frequency sensitivity for visual forms. Most importantly, we also tested the extent to which SC visual representations are similar to those in the primary visual cortex, which is the main gateway to subsequent visual processing in cortical ventral and dorsal stream areas. We used neuronal population recording and manipulation techniques in nonhuman primates (rhesus macaques), and we also characterized eye movement properties and how they might reflect either cortical or collicular visual processing represenations. Finally, we inactivated the primary visual cortex and are discovering intriguing properties of visual-motor pathways bypassing it. Our experiments have demonstrated neuronal computations for vision that are performed outside of visual cortex, thereby, having a major impact on our understanding of visual processing pathways in primates.
Projektbezogene Publikationen (Auswahl)
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Task-Irrelevant Visual Forms Facilitate Covert and Overt Spatial Selection. The Journal of Neuroscience, 40(49), 9496-9506.
Bogadhi, Amarender R.; Buonocore, Antimo & Hafed, Ziad M.
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Active vision at the foveal scale in the primate superior colliculus. Journal of Neurophysiology, 125(4), 1121-1138.
Hafed, Ziad M.; Chen, Chih-Yang; Tian, Xiaoguang; Baumann, Matthias P. & Zhang, Tong
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Faster Detection of “Darks” than “Brights” by Monkey Superior Colliculus Neurons. The Journal of Neuroscience, 42(50), 9356-9371.
Malevich, Tatiana; Zhang, Tong; Baumann, Matthias P.; Bogadhi, Amarender R. & Hafed, Ziad M.
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Express detection of visual objects by primate superior colliculus neurons. Scientific Reports, 13(1).
Bogadhi, Amarender R. & Hafed, Ziad M.
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Sensory tuning in neuronal movement commands. Proceedings of the National Academy of Sciences, 120(38).
Baumann, Matthias P.; Bogadhi, Amarender R.; Denninger, Anna F. & Hafed, Ziad M.
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Visual feature tuning properties of stimulus-driven saccadic inhibition in macaque monkeys. Journal of Neurophysiology, 130(5), 1282-1302.
Khademi, Fatemeh; Zhang, Tong; Baumann, Matthias P.; Buonocore, Antimo; Malevich, Tatiana; Yu, Yue & Hafed, Ziad M.
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Visual Functions of the Primate Superior Colliculus. Annual Review of Vision Science, 9(1), 361-383.
Hafed, Ziad M.; Hoffmann, Klaus-Peter; Chen, Chih-Yang & Bogadhi, Amarender R.
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Visual Feature Tuning Properties of Short-Latency Stimulus-Driven Ocular Position Drift Responses during Gaze Fixation. The Journal of Neuroscience, 44(13), e1815232024.
Khademi, Fatemeh; Zhang, Tong; Baumann, Matthias P.; Malevich, Tatiana; Yu, Yue & Hafed, Ziad M.
