Figure 2.

(A) The superior-inferior extent of brainstem structures on the left (blue) and right (red) from the present dataset. Regions are indicated on the abscissa, and the presence of the regions from superior (upper) to inferior (lower) is indicated in 250-micrometer increments on the ordinate. The right-hand side indicates the divisions of the brainstem into midbrain, pons, and medulla. Note that the unpaired cerebral aqueduct and periaqueductal gray are not included. (B) Comparison of the superior-inferior extent of brainstem structures from the present dataset (Allan Johnson, blue) with the Paxinos and Huang (1995) atlas (green). All conventions are as in 2A. Note that some regions that were identified in the present dataset (i.e., reticular formation, pontine nuclei, corticospinal tract, cerebral peduncle) were not identified in the Paxinos and Huang atlas per se and were removed for purposes of clarity.