Profound contrast adaptation early in the visual pathway.
Prior exposure to a moving grating of high contrast led to a substantial and persistent reduction in the contrast sensitivity of neurons in the lateral geniculate nucleus (LGN) of macaque. This slow contrast adaptation was potent in all magnocellular (M) cells but essentially absent in parvocellular (P) cells and neurons that received input from S cones. Simultaneous recordings of M cells and the potentials of ganglion cells driving them showed that adaptation originated in ganglion cells. As expected from the spatiotemporal tuning of M cells, adaptation was broadly tuned for spatial frequency and lacked orientation selectivity. Adaptation could be induced by high temporal frequencies to which cortical neurons do not respond, but not by low temporal frequencies that can strongly adapt cortical neurons. Our observations confirm that contrast adaptation occurs at multiple levels in the visual system, and they provide a new way to reveal the function and perceptual significance of the M pathway.
Solomon
Samuel G
SG
Center for Neural Science, New York University, New York, NY 10003, USA.
Peirce
Jonathan W
JW
Dhruv
Neel T
NT
Lennie
Peter
P
D000200:Action Potentials / Q000528:radiation effects; D000222:Adaptation, Physiological / Q000502:physiology*; D000818:Animals; D015350:Contrast Sensitivity / Q000502:physiology*; D004192:Discrimination, Psychological / Q000502:physiology; D004307:Dose-Response Relationship, Radiation; D005829:Geniculate Bodies / Q000166:cytology / Q000469:parasitology; D008252:Macaca fascicularis; D008297:Male; D008959:Models, Neurological; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D012160:Retina / Q000502:physiology; D012684:Sensory Thresholds / Q000502:physiology; D013998:Time Perception / Q000502:physiology; D014795:Visual Pathways / Q000502:physiology*