The thalamic reticular nucleus is part of the ventral thalamus that forms a capsule around the thalamus laterally. However, recent evidence from mice and fish question this statement and define it as dorsal thalamic structure. It is separated from the thalamus by the external medullary lamina. Reticular cells are GABAergic, and have discoid dendritic arbors in the plane of the nucleus. The thalamic reticular nucleus is part of the ventral thalamus that forms a capsule around the thalamus laterally. However, recent evidence from mice and fish question this statement and define it as dorsal thalamic structure. It is separated from the thalamus by the external medullary lamina. Reticular cells are GABAergic, and have discoid dendritic arbors in the plane of the nucleus.