V1 orientation plasticity is explained by broadly tuned feedforward inputs and intracortical sharpening

Area of Science:

• Neuroscience
• Computational Neuroscience
• Visual Cortex Plasticity

Background:

• Orientation adaptation and perceptual learning induce changes in V1 cell orientation tuning curves.
• Previous models, like the recurrent model (RM), explain plasticity but not for simple cells.
• Feedforward models, such as the modified feedforward model (MFM), may incorporate plasticity but require further investigation.

Purpose of the Study:

• To compare the ability of the modified recurrent model (MRM) and the modified feedforward model (MFM) to explain orientation plasticity.
• To investigate both pre- and postsynaptic plasticity mechanisms within these models.
• To determine the key features necessary for modeling orientation plasticity in simple and complex cells.

Main Methods:

• Simulated orientation plasticity in the MRM and MFM, incorporating both feedforward and recurrent connections.
• Investigated pre- and postsynaptic plasticity mechanisms.
• Compared model predictions against known effects of orientation adaptation and perceptual learning.

Main Results:

• The MRM successfully accounted for all observed learning- and adaptation-induced plasticity in both simple and complex cells.
• The MFM failed to replicate the observed plasticity, indicating limitations in feedforward models.
• Broadly tuned feedforward inputs and Mexican hat-like intracortical interactions were identified as crucial for plasticity in the MRM.

Conclusions:

• The MRM provides a comprehensive framework for understanding orientation plasticity in the visual cortex.
• Feedforward models, even with recurrent interactions, are insufficient to explain observed plasticity.
• The study predicts that cells with purely feedforward orientation tuning mechanisms will lack plastic properties.