Numerosity adaptation suppresses early visual responses.

Area of Science:

• Neuroscience
• Cognitive Science
• Visual Perception

Background:

• Humans and animals possess innate numerosity perception.
• Numerosity perception is modulated by adaptation to previously viewed quantities.
• Neural populations in frontal and parietal regions are tuned to specific numerosities and affected by adaptation.

Purpose of the Study:

• To investigate the neural effects of numerosity adaptation on early visual processing using ultra-high field fMRI.
• To examine how adaptation to higher numerosities influences monotonic early visual responses.
• To determine the progression of neural adaptation effects across the visual hierarchy.

Main Methods:

• Ultra-high field (7 Tesla) functional magnetic resonance imaging (fMRI) was employed.
• Participants viewed visual scenes with varying numerosities.
• Neural responses in early visual areas (V1-V3, hV4, LO1-LO2, V3A/B) and frontoparietal regions were recorded before and after adaptation stimuli.

Main Results:

• Monotonic increases in early visual responses with numerosity became less pronounced after adaptation to higher numerosities.
• The neural adaptation effect strengthened progressively through the early visual hierarchy (V1 to V3A/B).
• Distinct neural adaptation effects were observed in both early visual and frontoparietal areas.

Conclusions:

• Numerosity adaptation influences both early visual processing and frontoparietal numerosity-tuned responses.
• These findings provide neural evidence consistent with perceptual numerosity adaptation.
• The study highlights the hierarchical nature of neural adaptation in the visual system.