Related Experiment Video
Updated: May 27, 2025
Investigating Object Representations in the Macaque Dorsal Visual Stream Using Single-unit Recordings
Published on: August 1, 2018
Neural sensitivity to radial frequency patterns in the visual cortex of developing macaques
C L Rodríguez Deliz1, Gerick M Lee1,2, Brittany N Bushnell1
1Center for Neural Science, New York University, New York, NY 10003, USA.
Insights
Infant visual perception improves with age, but early visual cortex (V1) neural development doesn't fully explain it. Higher visual areas like V4 show early global form processing, suggesting their maturation is key to developing vision.
Area of Science:
- Neuroscience
- Developmental Biology
- Visual System Research
Background:
- Infant visual perception, including resolution and form recognition, matures gradually.
- Neural development in early visual pathways (retina, LGN, V1) in primates partially explains perceptual improvements but not entirely.
- The role of higher visual areas (V2, V4, IT) in supporting complex perceptual abilities during development remains unclear.
Purpose of the Study:
- To investigate the neural basis of developing visual form perception in infant nonhuman primates.
- To determine which visual areas (V1, V2, V4, IT) contribute to processing global form stimuli during early development.
- To correlate neural processing in visual areas with age-related improvements in behavioral visual sensitivity.
Main Methods:
- Recorded neural population responses to radial frequency patterns (global form stimuli) in V1, V2, V4, and IT.
- Studied three young monkeys (19-54 weeks) and one adult animal.
- Analyzed neural decoding performance across different visual areas and ages.
Main Results:
- Neurons and neural populations in V4 reliably encoded global form from the earliest ages studied.
- V1 neurons did not show reliable global form encoding at early ages.
- V2 and IT populations exhibited some selectivity for global form stimuli at early ages, particularly at higher radial frequencies.
- No significant age-related changes in neural decoding performance were found to fully account for behavioral improvements.
- V4 neural populations demonstrated highest sensitivity for higher radial frequencies, rich in curvature and orientation cues.
Conclusions:
- The maturation of higher visual areas, particularly V4, plays a crucial role in the development of global form perception.
- Early V4 function in processing complex visual stimuli may be a key factor limiting or enabling infant visual development.
- Findings suggest that downstream visual areas, beyond V1, are critical for explaining age-related gains in visual sensitivity and form perception.
Abstract:
Visual resolution, contrast sensitivity and form perception improve gradually with age. In nonhuman primates, the sensitivity and resolution of cells in the retina, lateral geniculate nucleus and primary visual cortex (V1) also improve, but not enough to account for the perceptual changes. So, what aspects of visual system development limit visual sensitivity in infants? Improvements in behavioral sensitivity might arise from maturation of regions downstream of V1 such as V2, V4 and pIT, which are thought to support increasingly complex perceptual abilities. We recorded the responses of populations of neurons in areas V1, V2, V4, and pIT to radial frequency patterns - a type of global form stimulus. Subjects were three young monkeys between the ages of 19 and 54 weeks, and a single adult animal. We found that neurons and neural populations in V4 reliably encoded global form in radial frequency stimuli at the earliest ages we studied, while V1 neurons do not. V2 and pIT populations also showed some degree of selectivity for these patterns at early ages, especially at higher radial frequency values. We did not find significant, systematic changes in neural decoding performance that could account for the improvement in behavioral performance over the same age range in an overlapping group of animals (Rodriguez Deliz et al., 2024). Finally, consistent with our prior behavioral results, neural populations in V4 show highest sensitivity for the higher radial frequency values which contain the highest concentration of curvature and orientation cues.
