What are the subdivisions of Layer IV in the primary visual cortex?

What are the subdivisions of Layer IV in the primary visual cortex?

• A. IVA, IVB, and IVC.
• B. IA, IIB, and IVC
• C. IVA, IVC, and IVD
• D. IV1, IV2, and IV3

Answer: (A)

Layer 4 of the primary visual cortex is not a uniform stripe; it’s subdivided into distinct sublamina that reflect different input and output patterns. The subdivisions commonly named are IVA, IVB, and IVC. The IVC portion receives the main thalamic input from the LGN (often discussed as IVCα and IVCβ to distinguish different thalamic streams), while IVA and IVB participate in relaying information onward to the supragranular layers and into other processing streams. This organizational scheme explains why you see these three specific sublamina as the recognized divisions of layer 4. Other naming schemes don’t correspond to the standard subdivisions used for layer 4 in the primary visual cortex.

Layer 4 of the primary visual cortex is not a uniform stripe; it’s subdivided into distinct sublamina that reflect different input and output patterns. The subdivisions commonly named are IVA, IVB, and IVC. The IVC portion receives the main thalamic input from the LGN (often discussed as IVCα and IVCβ to distinguish different thalamic streams), while IVA and IVB participate in relaying information onward to the supragranular layers and into other processing streams. This organizational scheme explains why you see these three specific sublamina as the recognized divisions of layer 4. Other naming schemes don’t correspond to the standard subdivisions used for layer 4 in the primary visual cortex.