The nomenclature, or naming conventions, used here follow those suggested by George Paxinos and his colleagues in the preparation of their atlases of the rat, mouse, monkey and human, cited below. To quote the authors of these magnificent brain atlases.: There is a critical need for a stable neuroanatomical nomenclature to accurately and intelligibly convey information between neuroscientists. At the present time, many terms are used for the same structure, and, in some cases, the same term is used for completely different structures." "We have made an effort to establish homologies and are using the same abbreviations for homologous structures in the atlases of the rat ( Paxinos and Watson, 1986), mouse (Franklin and Paxinos, 19 ), monkey (Paxinos et al., 1990; Mai et al., 1987) and human brainstem ("Paxinos and Huang, 1995) ... "The abbreviations used in the present and our other work were developed using the following principles". "

1. The abbreviations represent the order of words as spoken in English (e.g., DLG=dorsal lateral geniculate nucleus).

2. Capital letters represent nuclei, and lower case letters represent fiber tracts. Thus, the letter "N" has not been used to denote nuclei, and the letter "t" has not been used to denote fiber tracts.

3. The general principle used in the abbreviations of the names of elements in the periodic table was followed: the capital letter representing the first letter of a word in a nucleus is followed by the lower case letter most characteristic of that word ( not necessarily the second letter; e.g., Mg = Magnesium, Rt = reticular thalamic nucleus).

4. Compound names of nuclei have a capital letter for each part (e.g., LPGi = lateral paragigantocellular nucleus).

5. If a word occurs in the names of a number of structures, it is usually given the same abbreviation (e.g., Rt = reticular thalamic nucleus, RtTg = reticulotegmental nucleus of the pons). Exceptions to this rule are made for well-established abbreviations such as VTA (i.e., ventral tegmental area).

6. Abbreviations of brain regions are omitted where the identity of the regions in question is clear from its position (CMn = centromedian thalamic nucleus, not CMnTh).

7. Arabic numerals are used instead of Roman numerals in identifying (a) cranial nerves and nuclei (as in the Berman atlas (1986) and (b) layers of the spinal cord. While the spoken meaning is the same, the detection threshold is lower, ambiguity is reduced, and they are easier to position in small spaces available on diagrams."

"The delineations and descriptions of nuclei and fiber tracts can be found in a number of different reviews."