Encoding Path and Place
We recorded neuronal activity in monkey medial superior temporal (MST) cortex during movement on a motorized sled. Most neurons showed a preferred heading direction, but some responded only when that heading was part of a particular path.
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Influence of Attention on Neuronal Responses
Optic flow selectively activates neurons in medial superior temporal (MST) cortex. We find that many MST neurons yield larger and more selective responses when the optic flow guides a subsequent eye movement. Smaller, less selective responses are seen when optic flow is preceded by a flashed precue that guides eye movements.
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Navigation in Alzheimer's Disease
Our findings in monkey cortical neurophysiology led us to consider the potential role of disordered optic flow analysis in human visuospatial disorientation. The visuospatial disorientation of Alzheimer's disease (AD) has several relevant features: patients get lost despite their recognizing landmarks, describing the route, recognizing familiar landmarks, and showing relative preservation of other capacities.
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Neuronal Integration of Visual Cues
Combined object motion and optic flow evoke a wide variety of response interactions with landmark and animate objects creating comparable effects. When baseline activity is subtracted, response interactions are distributed around simple additivity with a substantial number of sub-additive and super-additive responses.
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Neuronal Mechanisms of Distracted Driving
We presented naturalistic combinations of virtual self-movement stimuli while recording neuronal activity in monkey cerebral cortex. The monkeys used a joystick to steer their simulated heading direction guided by either object motion or optic flow.
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Optic Flow Evoked Potentials
We developed an approach to using radial optic flow stimuli to elicit visual motion evoked potentials. Subjects view a random pattern of stationary dots and after a few hundred milliseconds, the dots move to create a radial pattern of optic flow. We record the responses to optic flow onset and compare the N200 response amplitudes across subject groups.
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Receptive Field Dynamics
Optic flow informs moving observers about their heading direction. Neurons in monkey medial superior temporal (MST) cortex show heading selective responses to optic flow and planar direction selective responses to patches of local motion.
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Sensory Interactions and Population Encoding
Dorsal medial superior temporal cortex (MSTd)’s population response encodes heading direction from optic flow seen during fixation or pursuit. Vestibular responses in these neurons might enhance heading representation during self-movement in light or provide an alternative basis for heading representation during self-movement in darkness.
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