Abstract
From mammals to insects, locomotion has been shown to strongly modulate visual-system physiology. Does the manner in which a locomotor act is initiated change the modulation observed? We performed patch-clamp recordings from motion-sensitive visual neurons in tethered, flying Drosophila. We observed motor-related signals in flies performing flight turns in rapid response to looming discs and also during spontaneous turns, but motor-related signals were weak or non-existent in the context of turns made in response to brief pulses of unidirectional visual motion (i.e., optomotor responses). Thus, the act of a locomotor turn is variably associated with modulation of visual processing. These results can be understood via the following principle: suppress visual responses during course-changing, but not course-stabilizing, navigational turns. This principle is likely to apply broadly-even to mammals-whenever visual cells whose activity helps to stabilize a locomotor trajectory or the visual gaze angle are targeted for motor modulation.
Highlights
Motor signals modulate sensory physiology in varied brain regions and during diverse actions, from the twitching of facial muscles to the act of locomotion.[1,2,3,4,5] A deeper understanding of the function of these motor-related modulations would be an important step forward for systems neuroscience.An intriguing aspect of motor control is that the same physical movement can serve different functions depending on context
A very strong gust of wind might come and cause this person’s body to rotate during the jog, which might drive them to quickly turn back toward their initial direction of travel. Such turning-back behavior is a course-stabilizing turn in that its purpose is to help maintain a consistent navigational trajectory after an unexpected perturbation. Should we expect this person’s visual system to be modulated the same way during all the abovementioned turns—if the kinematics were generally matched—or might course-changing and course-stabilizing navigational turns lead to different modulations because their behavioral purpose is different? Answering this question might illuminate at least some of the reasons why sensory physiology is so pervasively modulated by movement
horizontal system (HS) cells on the right side of the fly brain are depolarized by clockwise rotational visual motion and they are hyperpolarized by counterclockwise motion (Figure 1C)
Summary
Motor signals modulate sensory physiology in varied brain regions and during diverse actions, from the twitching of facial muscles to the act of locomotion.[1,2,3,4,5] A deeper understanding of the function of these motor-related modulations would be an important step forward for systems neuroscience.An intriguing aspect of motor control is that the same physical movement can serve different functions depending on context. For example, a person jogging in nature This individual is likely to make many internally initiated or spontaneous navigational turns as they explore their new environment. A very strong gust of wind might come and cause this person’s body to rotate during the jog, which might drive them to quickly turn back toward their initial direction of travel. Such turning-back behavior is a course-stabilizing turn in that its purpose is to help maintain a consistent navigational trajectory after an unexpected perturbation. Should we expect this person’s visual system to be modulated the same way during all the abovementioned turns—if the kinematics were generally matched—or might course-changing and course-stabilizing navigational turns lead to different modulations because their behavioral purpose is different? Answering this question might illuminate at least some of the reasons why sensory physiology is so pervasively modulated by movement
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