What does the feedforward projection from Layer 4 do?

What does the feedforward projection from Layer 4 do?

• A. Sends modulatory signals to the LGN.
• B. Directs retinal signals to the cortex.
• C. Receives LGN input and projects to higher visual areas.
• D. Conveys signals to the superior colliculus.

Answer: (C)

Layer 4 in the primary visual cortex is the main entry point for LGN input, and its feedforward output carries that thalamic drive upward to the supragranular layers (2/3) and onward to higher visual areas. This bottom-up flow is how simple retinotopic signals get transformed into more complex representations as processing moves through the cortical hierarchy. It isn’t about sending signals back to the LGN (that would be feedback), nor about routing retinal signals directly to cortex (the input stage is LGN to Layer 4), and it isn’t a path to the superior colliculus (a separate subcortical route).

Layer 4 in the primary visual cortex is the main entry point for LGN input, and its feedforward output carries that thalamic drive upward to the supragranular layers (2/3) and onward to higher visual areas. This bottom-up flow is how simple retinotopic signals get transformed into more complex representations as processing moves through the cortical hierarchy. It isn’t about sending signals back to the LGN (that would be feedback), nor about routing retinal signals directly to cortex (the input stage is LGN to Layer 4), and it isn’t a path to the superior colliculus (a separate subcortical route).