The Lacertilian Forebrain 
73 
(Karten, 1968; Karten et al., 1973) appear 
to correspond to the tecto-pulvinar-extra- 
striate and auditory system projections in 
mammals. Additionally, projections to the 
DVR from dorsal cortex have been described 
in turtles (Northcutt, 1970) and snakes 
(Halpern, 1976). 
A recent study of the DVR in the lizard 
Tupinamhis (Sligar and Voneida, 1976) 
demonstrated efferent projections to nucleus 
rotundus and to the hypothalamus. As is the 
case in Gekko (Butler 1976) and in birds 
(Zeier and Karten 1973), no evidence of 
projections to the contralateral DVR was 
found. Interhemispheric connections of the 
DVR via the anterior commissure were, 
however, found in turtles (Northcutt, 1970, 
1974). The latter pathway may be similar to 
the interneocortical connection which, in 
monotremes and marsupials (Ebner, 1969) 
as well as in eutherian mammals (Ebner and 
Myers, 1965), travels via the anterior com- 
missure. 
On the basis of these data, particularly the 
findings of ascending visual and auditory 
pathways, the dorsal ventricular ridge ap- 
pears to correspond to parts of mammalian 
neocortex receiving similar projections. The 
cell populations in the DVR which have been 
identified as visual and auditory occupy, how- 
ever, only a small portion of the entire ridge. 
The circuitry of most regions of the DVR 
still needs to be worked out. 
Dorsal cortex: Ascending afferent connec- 
tions. As discussed above, the dorsal cortex 
has been found to receive ascending visual 
projections from the dorsal lateral geniculate 
nucleus in turtles (Hall and Ebner, 19706; 
Foster et al., 1976) and birds (Karten et al., 
1973). In birds this pallial telencephalic 
region is called the Wulst, and the projections 
from the dorsal geniculate (nucleus opticus 
principalis thalami) are confined to its lat-' 
eral part. The medial part (Karten et al., 
1973) receives projections from medially 
situated nonvisual thalamic nuclei including 
nucleus dorsolateralis anterior. In both 
turtles (Foster, et al., 1976) and lizards 
(Distel and Ebbesson, 1975) a projection to 
dorsal cortex from nucleus dorsolateralis 
anterior has also been found. 
Dorsal- cortex: Ipsilateral efferent projec- 
tions. In lizards (Lohman and Mentink, 
1972; Butler, 1976) and snakes (Halpern, 
1974, 1976; Ulinski, 1975), lesions of the 
dorsal cortex result in degeneration in the 
molecular layer of medial cortex and in the 
septum. Additionally, efferent projections to 
the posterior part of the DVR and to nucleus 
anterior of Warner in the dorsal thalamus 
have been found in snakes (Halpern, 1976), 
and projections to hypothalamus in lizards 
(Lohman and Van Woerden-Verkley, 1976). 
The dorsal cortex also projects to the DVR 
in turtles (Northcutt, 1970) and in lizards 
(Lohman and Van Woerden-Verkley, 1976). 
In birds the lateral Wulst projects to a region 
of the DVR called the periectostriatal belt 
that surrounds the rotundal projection field 
(Karten et al., 1973). 
Descending projections of dorsal cortex to 
the dorsal lateral geniculate nucleus have 
been reported in turtles (Hall and Ebner, 
1974 ; Ware, 1974), as has a projection of the 
Wulst to nucleus opticus principalis thalami 
in birds (Karten et al., 1973). In turtles, 
projections have also been traced to nuclei 
rotundus and reunions in the dorsal thalamus 
(Ware, 1974) and to the midbrain tegmen- 
tum (Hall and Ebner, 1974; Ware, 1974). 
Dorsal cortex: Interhemispheric connec- 
tions. While commissural projections of dor- 
sal cortex were not found in the lizard Tupin~ 
ambis (Voneida and Ebbesson, 1969 ; Lohman 
and Mentink, 1972), nor in turtles (Ware, 
1974) or snakes (Ulinski, 1975; Halpern, 
1976), they appear to be present in the lizard 
Gekko (Butler, 1976). Additionally, in Gekko, 
the dorsal cortex projects to part of the 
molecular layer of the contralateral medial 
cortex. These projections pass to the contra- 
lateral hemisphere in the hippocampal 
(dorsal pallial) commissure. A similar path- 
way was found in the turtle Chrysemys 
(Northcutt, 1970). 
