At Gestational week 7 the cortical plate begins to develop

At gestational week 7, a critical phase in brain development commences as the cortical plate begins to develop. Here is an explanation of the significance of gestational week 7 in the context of cortical plate development:

1.  Initiation of Cortical Plate Formation: Around gestational week 7, radially migrating neurons originating from the ventricular and subventricular zones initiate the development of the cortical plate. The cortical plate is a crucial structure in the developing brain that gives rise to the six distinct layers of the neocortex, the outer layer of the cerebral hemispheres responsible for higher cognitive functions.

2.     Early Cortical Layering: During the initial stages of cortical plate development, the structure is divided into two primary layers: the thin superficial marginal zone and the underlying subplate. The marginal zone contains cells that have migrated tangentially, while the subplate houses a mix of interneurons and post migratory pyramidal neurons. These early layers play essential roles in guiding the subsequent formation of the cortical layers.

3.     Inside-Out Formation of the Cortex: The cortical plate undergoes an inside-out formation process, where cortical neurons accumulate in a sequential manner. The earliest-born neurons destined to become the innermost layer 6 are followed by neurons that will form the outer layer 2. This inside-out sequence of neuronal migration and layer formation is crucial for establishing the laminar organization of the neocortex, which is essential for its functional specialization.

4.     Role of Radial Glial Cells: Radial glial cells, a type of neural stem cell that serves as a scaffold for neuronal migration, play a pivotal role in guiding the movement of neurons from the proliferative zones to their final destinations in the cortical plate. These cells provide structural support and guidance cues for migrating neurons, ensuring the proper positioning of neurons within the developing cortex.

5. Formation of Cortical Layers: The cortical plate development process ultimately leads to the formation of the six distinct layers of the neocortex. Each cortical layer contains specific types of neurons and plays unique roles in information processing and neural circuitry. The establishment of these layers is critical for the functional organization of the cerebral cortex and the development of complex cognitive abilities.

In summary, gestational week 7 marks a crucial stage in brain development when the cortical plate begins to form, setting the foundation for the intricate structure of the neocortex. The early events during cortical plate development, including neuronal migration, layering, and the inside-out formation of the cortex, are essential for establishing the laminar organization and functional specialization of the developing brain. Understanding the processes that unfold during cortical plate development is key to unraveling the complexities of brain development and the emergence of higher cognitive functions in the mature brain.