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Silencing "Top-Down" Cortical Signals Affects Spike-Responses of Neurons in Cat's "Intermediate" Visual Cortex
Jin Y Huang1,2,3, Chun Wang1,3, Bogdan Dreher1,3
1Discipline of Anatomy and Histology, The University of SydneySydney, NSW, Australia.
Frontiers in Neural Circuits
|May 11, 2017
Summary
Feedback from the postero-temporal visual cortex modulates visual processing in area 19. Inactivating this feedback alters neuron responses, direction selectivity, and preferred stimulus velocity, impacting motion perception.
Area of Science:
- Neuroscience
- Visual Cortex Research
- Sensory Processing
Background:
- The visual cortex processes complex information, with different areas specializing in specific features like form and motion.
- Feedback pathways, particularly from higher-order visual areas, are thought to play a role in modulating neural activity and receptive field properties.
- The specific contribution of feedback from the postero-temporal visual (PTV) cortex to intermediate visual areas like area 19 remains to be fully elucidated.
Purpose of the Study:
- To investigate the effects of reversible inactivation of the postero-temporal visual (PTV) cortex on neuronal activity in area 19.
- To determine how feedback signals from PTV influence background activity, stimulus-evoked responses, direction selectivity, and velocity tuning in area 19 neurons.
- To understand the role of PTV feedback in shaping the functional specialization of area 19 for visual stimulus processing.
Main Methods:
- Reversible inactivation of the postero-temporal visual (PTV) cortex in anesthetized domestic cats.
- Electrophysiological recording of single neuron background activity and spike responses in the ipsilateral cytoarchitectonic area 19 (V3).
- Analysis of changes in response magnitude, direction selectivity index (DSI), preferred orientation, and preferred stimulus velocity.
Main Results:
- PTV inactivation caused reversible changes in response magnitude (35.5%), direction selectivity (43%), and preferred stimulus velocity (37%) in area 19 neurons.
- Reduced background activity was occasionally observed (2/28) upon PTV silencing.
- Similar upward shifts in preferred velocities were observed in area 17 (V1) neurons, often accompanied by increased DSIs, suggesting a broader role of PTV feedback.
Conclusions:
- Feedback from the higher-order PTV cortex significantly modulates stimulus velocity preferences and direction selectivity in area 19 neurons.
- PTV feedback plays a crucial role in determining the magnitude of spike responses and motion-related receptive field properties in area 19.
- The specialization of area 19 for processing stationary or slowly moving stimuli is partly shaped by feedback from higher-order visual areas.
