The subdivisions IVA, IVB, and IVC are subdivisions of which cortical layer?

The subdivisions IVA, IVB, and IVC are subdivisions of which cortical layer?

• A. Layer II/III
• B. Layer V
• C. Layer IV
• D. Layer VI

Answer: (C)

Layer IV is the granular cortical layer that receives the bulk of thalamic sensory inputs. In many primary sensory areas, this layer is further divided into sublayers IVA, IVB, and IVC, reflecting distinct thalamic afferents and local processing within the granular zone. Thalamic inputs from sensory nuclei project mainly to Layer IV, which is why these subdivisions sit there. By contrast, Layer II/III is mainly involved in intracortical communication, Layer V sends major outputs to subcortical targets, and Layer VI provides feedback to the thalamus. So, those subdivisions belong to Layer IV.

Layer IV is the granular cortical layer that receives the bulk of thalamic sensory inputs. In many primary sensory areas, this layer is further divided into sublayers IVA, IVB, and IVC, reflecting distinct thalamic afferents and local processing within the granular zone. Thalamic inputs from sensory nuclei project mainly to Layer IV, which is why these subdivisions sit there. By contrast, Layer II/III is mainly involved in intracortical communication, Layer V sends major outputs to subcortical targets, and Layer VI provides feedback to the thalamus. So, those subdivisions belong to Layer IV.