Krauzlis Lab Projects

The links between eye movements, attention and perception

The concept of a movement goal provides an elegant way to link higher-order sensory functions such as attention and perception to the output pathways that formulate the final motor commands. For example, we showed that the activity of SC neurons is modulated by the early removal of a fixated stimulus (Krauzlis et al., 2002; Krauzlis, 2003) (a.k.a. the “gap paradigm”), a manipulation known to modulate attention and speed up reaction times. For many neurons, changes in activity were correlated with the changes in latencies for both pursuit and saccades, providing a neural correlate of the shared effects on reaction time we found previously (Krauzlis and Miles, 1996a, b). These and other results (Liston and Krauzlis, 2003) argue that the same signals involved in the covert preparation of saccades also mediate the selection of goals for pursuit. Because the covert preparation of saccades is itself related to visual attention, the coordination between pursuit and saccades might be a natural consequence of attention and other descending signals influencing SC activity.
If identifying the goal for pursuit involves the SC, which contains a map of visual space, triggering pursuit should be strongly influenced by spatial information. This prediction was confirmed by our finding in human subjects that information about the location of an upcoming target has a larger effect on pursuit latencies than information about its direction of motion (Adler et al., 2002). Thus, for triggering pursuit it is more important to know where the target will be than to know in which direction it will move.
We have explored this premise – that eye movement goals are strongly influenced by higher-order processes like attention, perception and cognition – more thoroughly with human subjects. We showed that prior information about the likely direction of motion of an upcoming stimulus has similar effects on both pursuit and perception, not only on average, but also on a trial-by-trial basis (Krauzlis and Adler, 2001). Applying a similar analysis to the perceptual and pursuit responses during a direction discrimination task, we estimated how much of the variability in performance was due to a common noisy input, providing evidence for a shared ensemble of neurons contributing to both pursuit and perception (Stone and Krauzlis, 2003). We have also measured the relative timing of perception and pursuit. Using an apparent motion stimulus that is perceptually bi-stable, we showed that pursuit can follow the changes in perceptual state and does so with a surprisingly short delay of approximately 50 ms (Madelain and Krauzlis, 2003). These results demonstrate that eye movements can provide a real-time and independent measure of cognitive and perceptual states.

References

Adler SA, Bala J, Krauzlis RJ (2002) Primacy of spatial information in guiding target selection for pursuit and saccades. J Vis 2:627-644. PDF

Krauzlis RJ (2003) Neuronal activity in the rostral superior colliculus related to the initiation of pursuitand saccadic eye movements. J Neurosci 23:4333-4344. PDF

Krauzlis RJ, Miles FA (1996a) Release of fixation for pursuit and saccades in humans: evidence for shared inputs acting on different neural substrates. J Neurophysiol 76:2822-2833. PDF

Krauzlis RJ, Miles FA (1996b) Decreases in the latency of smooth pursuit and saccadic eye movements produced by the "gap paradigm" in the monkey. Vision Res 36:1973-1985. PDF

Krauzlis RJ, Adler SA (2001) Effects of directional expectations on motion perception and pursuit eye movements. Vis Neurosci 18:365-376. PDF

Krauzlis RJ, Dill N, Kornylo K (2002) Activity in the primate rostral superior colliculus during the "gap effect" for pursuit and saccades. Ann N Y Acad Sci 956:409-413. PDF

Liston, D., and Krauzlis, R.J., Shared response preparation for pursuit and saccadic eye movements, J. Neuroscience, 23: 11305-11314, 2003. PDF

Madelain, L., and Krauzlis, R.J., Pursuit of the ineffable: perceptual and motor reversals during the tracking of apparent motion, J. Vision, 3: 642-653, 2003. PDF

Stone, L.S., and Krauzlis, R.J., Shared motion signals for human perceptual decisions and oculomotor actions, J. Vision, 3: 725-736, 2003. PDF



Home: Projects: The links between eye movements, attention and perception

	The links between eye movements, attention and perception The concept of a movement goal provides an elegant way to link higher-order sensory functions such as attention and perception to the output pathways that formulate the final motor commands. For example, we showed that the activity of SC neurons is modulated by the early removal of a fixated stimulus (Krauzlis et al., 2002; Krauzlis, 2003) (a.k.a. the “gap paradigm”), a manipulation known to modulate attention and speed up reaction times. For many neurons, changes in activity were correlated with the changes in latencies for both pursuit and saccades, providing a neural correlate of the shared effects on reaction time we found previously (Krauzlis and Miles, 1996a, b). These and other results (Liston and Krauzlis, 2003) argue that the same signals involved in the covert preparation of saccades also mediate the selection of goals for pursuit. Because the covert preparation of saccades is itself related to visual attention, the coordination between pursuit and saccades might be a natural consequence of attention and other descending signals influencing SC activity. If identifying the goal for pursuit involves the SC, which contains a map of visual space, triggering pursuit should be strongly influenced by spatial information. This prediction was confirmed by our finding in human subjects that information about the location of an upcoming target has a larger effect on pursuit latencies than information about its direction of motion (Adler et al., 2002). Thus, for triggering pursuit it is more important to know where the target will be than to know in which direction it will move. We have explored this premise – that eye movement goals are strongly influenced by higher-order processes like attention, perception and cognition – more thoroughly with human subjects. We showed that prior information about the likely direction of motion of an upcoming stimulus has similar effects on both pursuit and perception, not only on average, but also on a trial-by-trial basis (Krauzlis and Adler, 2001). Applying a similar analysis to the perceptual and pursuit responses during a direction discrimination task, we estimated how much of the variability in performance was due to a common noisy input, providing evidence for a shared ensemble of neurons contributing to both pursuit and perception (Stone and Krauzlis, 2003). We have also measured the relative timing of perception and pursuit. Using an apparent motion stimulus that is perceptually bi-stable, we showed that pursuit can follow the changes in perceptual state and does so with a surprisingly short delay of approximately 50 ms (Madelain and Krauzlis, 2003). These results demonstrate that eye movements can provide a real-time and independent measure of cognitive and perceptual states. References Adler SA, Bala J, Krauzlis RJ (2002) Primacy of spatial information in guiding target selection for pursuit and saccades. J Vis 2:627-644. PDF Krauzlis RJ (2003) Neuronal activity in the rostral superior colliculus related to the initiation of pursuitand saccadic eye movements. J Neurosci 23:4333-4344. PDF Krauzlis RJ, Miles FA (1996a) Release of fixation for pursuit and saccades in humans: evidence for shared inputs acting on different neural substrates. J Neurophysiol 76:2822-2833. PDF Krauzlis RJ, Miles FA (1996b) Decreases in the latency of smooth pursuit and saccadic eye movements produced by the "gap paradigm" in the monkey. Vision Res 36:1973-1985. PDF Krauzlis RJ, Adler SA (2001) Effects of directional expectations on motion perception and pursuit eye movements. Vis Neurosci 18:365-376. PDF Krauzlis RJ, Dill N, Kornylo K (2002) Activity in the primate rostral superior colliculus during the "gap effect" for pursuit and saccades. Ann N Y Acad Sci 956:409-413. PDF Liston, D., and Krauzlis, R.J., Shared response preparation for pursuit and saccadic eye movements, J. Neuroscience, 23: 11305-11314, 2003. PDF Madelain, L., and Krauzlis, R.J., Pursuit of the ineffable: perceptual and motor reversals during the tracking of apparent motion, J. Vision, 3: 642-653, 2003. PDF Stone, L.S., and Krauzlis, R.J., Shared motion signals for human perceptual decisions and oculomotor actions, J. Vision, 3: 725-736, 2003. PDF
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