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Nilufar Razmi; Visual Adaptation to Temporal Sequences . Journal of Vision 2016;16(12):533. doi: 10.1167/16.12.533.
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© 2017 Association for Research in Vision and Ophthalmology.
Sensory adaptation happens when a neuron responds less to a repetitive and unchanged quality of a stimulus. Well-known adaptation effects exist for signals that are linked together across space, such as objects and faces. Possible adaptation to different signals that are linked to each other in time has been a much less studied field. Here we studied orientation adaptation to oriented gratings in a sequence of three gratings that repeated in time. The stimuli consisted of three gratings (100ms each, 200ms between each grating in sequence, 600 ms between sequences). In pre-adaptation phase, the first two were tilted 15° to right (or left) and a near vertical test grating followed those. A familiar tilt aftereffect was found here where the test grating was repelled from the two preceding stimuli. In adaptation phase the stimuli were two gratings tilted 15° to right (or left) and the last one to 15° left (or right). Subjects (N=3) viewed repetitions of this sequence. After that, the same sequence of pre-adapt test was shown. Compared to pre-adapt responses, subjects showed a statistically significant aftereffect (-2.2°± 0.78 p< 0.05, 1.6°±0.36 p< 0.01) in the opposite direction, which was repellent to orientation of the last grating in adapting sequence rather than repellant to the immediately preceding stimuli of the test sequence. In a control group (N=3) the pre-adapt was the same and the adapting pattern consisted of the same number of stimuli as previous group adapting patterns but shown in random order. No significant aftereffect was observed (-0.34°±0.4 p=0.2, 1.2°±1.7 p=0.2). Therefore this temporal contextual modulation effect cannot be explained by simple averaging of signals that make up the adapting sequence. These results suggest that visual system is able to extract patterns not only across space, but also across time and adapt to them.
Meeting abstract presented at VSS 2016
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