Cortex-restricted disruption of NMDAR1 impairs neuronal patterns in the barrel cortex

Area of Science:

• Neuroscience
• Developmental Biology
• Sensory Systems

Background:

• The somatosensory cortex contains topographic representations of sensory inputs like whiskers and paws.
• Neural activity, particularly via N-methyl-D-aspartate receptors (NMDARs), is implicated in sensory map development, but its precise role is debated.

Purpose of the Study:

• To investigate the necessity of cortical NMDARs for the development of somatosensory cortical maps and structures.

Main Methods:

• Generated genetically modified mice with NMDAR1 gene deletion specifically in excitatory cortical neurons.
• Examined the development of sensory pathways in the brainstem, thalamus, and somatosensory cortex using these mice.

Main Results:

• Sensory maps in the brainstem and thalamus developed normally.
• In the cortex, thalamocortical afferents for large whiskers showed some patterning and plasticity, but less distinctly than in controls.
• Patterns for sinus hairs and digits were largely absent.
• Cellular aggregates (barrels) and their boundaries failed to form, even where afferents clustered.

Conclusions:

• Cortical NMDARs are essential for the proper aggregation of layer IV cells into barrels.
• NMDARs are required for the complete development of thalamocortical patterns in the somatosensory cortex.