Cortical Layers Markers
The cerebral cortex is the most evolutionarily advanced structure of the human brain, supporting perception, cognition, language, memory, and complex behavior. During embryonic development, neural progenitors in the ventricular and subventricular zones generate the six classical cortical layers through an inside-out pattern of migration, establishing a highly ordered laminar architecture.
In the mature brain, each layer contains a characteristic composition of excitatory projection neurons and diverse classes of inhibitory interneurons, forming microcircuits specialized for integrating sensory information, coordinating motor output, and enabling higher-order cognition.
Layer-specific molecular markers provide essential tools to map this organization, revealing cell identities, developmental lineages, connectivity patterns, and disease-related alterations across the cortical column.
Cortical Layer–Specific Protein Markers (Including Interneuron Subtypes)
| Cortical Layer | Marker | Notes / Cell Type |
|---|---|---|
| Layer I | RELN | Cajal–Retzius cells; Reelin-high interneurons |
| Layer II/III | CUX1 | Upper-layer intratelencephalic neurons |
| CUX2 | Corticocortical projection neurons | |
| VIP | Vasoactive intestinal peptide interneurons; enriched in superficial layers | |
| RELN (interneurons) | VIP–RELN “neurogliaform” interneurons concentrated in upper layers | |
| Layer IV | RORB | Thalamorecipient sensory cortex neurons |
| RYR3 | Granular-layer enrichment | |
| GAD2 | General GABAergic interneuron marker; high density in granular layers | |
| LAMP5 | Neurogliaform interneurons enriched in L1–L3 but also present in L4 | |
| Layer V | BCL11B (CTIP2) | Corticospinal and subcerebral projection neurons |
| FEZF2 | Deep-layer corticofugal neurons | |
| PVALB | Fast-spiking parvalbumin interneurons; strong in mid–deep layers | |
| CHT (SLC18A3) | Subset of deep-layer interneurons with corticofugal modulation roles | |
| Layer VI | FOXP2 | Corticothalamic projection neurons |
| TBR1 | Early-born corticothalamic neurons | |
| SST | Somatostatin interneurons; enriched in deep layers V–VI | |
| NPY | Neuropeptide Y interneurons common in deep layers and subplate |
| Marker | L1 | L2/3 | L4 | L5 | L6 |
|---|---|---|---|---|---|
| RELN | High | Low | |||
| LAMP5 | High | Low | |||
| CUX1 | Very High | ||||
| CUX2 | Very High | ||||
| VIP | Moderate | Low | |||
| PVALB | High | Moderate | |||
| RORB | Very High | ||||
| BCL11B (CTIP2) | Very High | Low | |||
| FEZF2 | High | ||||
| SST | Moderate | High | |||
| FOXP2 | Low | Very High | |||
| TBR1 | Low | High |