Recently, this research team  used an automated extraction method (which is more efficient that the ROI method) in patients with OCD and found decreased blood flow in the left inferior temporal lobe, supramarginal gyrus, transverse temporal gyrus, outer dorsal nuclei, outer posterior nucleus, intercalated nucleus, and increased blood flow in the left superior parietal lobule, and the dorsal thalamus
. Overall these results indicate that Patients with OCD have decreased blood flow in multiple regions in the bilateral temporal lobes and increased blood flow in the dorsal thalamus
The entopallium, which is shown in Figure 2, is one such subregion, and it receives the ascending visual inputs relayed from the optic tectum (the avian counterpart of the mammalian superior colliculus) through the dorsal thalamus. Whether these various parts of the avian pallium are homologous to the neocortex, to the claustrum-endopiriform formation, or to the basolateral part of the pallial amygdala (all of which receive projections from collothalamic nuclei), to a combination of one or more of these structures, or to none of them remains unresolved (Bruce and Neary, 1995; Butler and Molnar, 2002; Northcutt and Kaas, 1995; Karten, 1997; Martinez-Garcia et al., 2002; Puelles et al., 2000; Reiner, 2000).
The so-called direct loop of cortex to dorsal striatum to globus pallidus to dorsal thalamus and back to cortex is a circuit that promotes the initiation of movement, while a second circuit that additionally involves the subthalamic nucleus, the so-called indirect loop, inhibits movement (Buchel et al., 1999; Graybiel, 2000; Kayahara and Nakano, 1996; Nakano et al., 1996; Hoover and Strick, 1999).
In birds, this nucleus (previously called the pars dorsalis of the superior reticular nucleus), as in mammals, contains GABAergic neurons (Veenman and Reiner, 1994; Sun et al., 2005), receives an input from the globus pallidus (Medina et al., 1997), and projects to various parts of the dorsal thalamus (Benowitz and Karten, 1976; Mpodozis et al., 1996).
As in mammals, the dorsal and ventral pallida each project to part of the dorsal thalamus and are involved in similar circuitry, with the dorsal striatum and pallidum being more involved in somatic functions and the ventral striatum and pallidum in limbic-related ones.
Thus both the so-called direct loop of pallial regions to dorsal striatum to globus pallidus to dorsal thalamus and back to pallium, a circuit that promotes the initiation of movement, and the so-called indirect loop, which involves the subthalamic nucleus and inhibits movement, are present in birds.
Both similarities and differences exist in the organization of the dorsal thalamus. As in birds but in contrast to mammals, reptiles have few reciprocal projections from the pallium to dorsal thalamic sensory relay nuclei.
The medial pallium is the main ascending target of projections from the rostral part of the dorsal thalamus (Northcutt and Kicliter, 1980), which does not receive direct retinal input but rather inhibitory input from ventral thalamic, retinorecipient cell groups (Roth et al., 2003).
The evolution of the dorsal thalamus of jawed vertebrates, including mammals: cladistic analysis and a new hypothesis.