Subcortical projections to the centromedian and parafascicular thalamic nuclei in the cat

Abstract

The primary objective of this study is to identify the totality of input to the centromedian and parafascicular (CM-Pf) thalamic nuclear complex. The subcortical projections upon the CM-Pf complex were studied in the cat with three different retrograde tracers. The tracers used were unconjugated horseradish peroxidase (HRP), horseradish peroxidase conjugated to wheat germ agglutinin WGA-HRP), and rhodamine-labeled fluorescent latex microspheres (RFM).Numerous subcortical structures or substructures contained labeled neurons with all three tracing techniques. These labeled structures included the central nucleus of the amygdala; the entopeduncular nucleus; the globus pallidus; the reticular and ventral lateral geniculate nuclei of the thalamus; parts of the hypothalamus including the dorsal, lateral, and posterior hypothalamic areas and the ventromedial and parvicellular nuclei; the zona incerta and fields of Forel; parts of the substantia nigra including the pars reticularis and pars lateralis, and the retrorubral area; the pretectum; the intermediate and deep layers of the superior colliculus; the periaqueductal gray; the dorsal nucleus of the raphe; portions of the reticular formation, including the mesencephalic, pontis oralis, pontis caudalis, gigantocellularis, ventralis, and lateralis reticular nuclei; the nucleus cuneiformis; the marginal nucleus of the brachium conjunctivum; the locus coeruleus; portions of the trigeminal complex, including the principal sensory and spinal nuclei; portions of the vestibular complex, including the lateral division of the superior nucleus and the medial nucleus; deep cerebellar nuclei, including the medial and lateral cerebellar nuclei; and lamina VII of the cervical spinal cord.Moreover, the WGA-HRP and rhodamine methods (known to be more sensitive than the HRP method) revealed several afferent sources not shown by HRP: the anterior hypothalamic area, ventral tegmental area, lateral division of the superior vestibular nucleus, nucleus interpositus, and the nucleus praepositus hypoglossi. Also, the rhodamine method revealed labeled neurons in laminae V and VI of the cervical spinal cord.

Thalamic interactions of cerebellum and basal ganglia

“…Indications of convergence in the rat Pf can be frequently found in anatomical (Faull and Carman 1978;Di Chiara et al 1979;Haroian et al 1981;Deniau et al 1992;Gerfen et al 1982;Wiklund and Cuénod 1984;Cornwall and Phillipson 1988) and electrophysiological studies (MacLeod et al 1980;MacLeod and James 1984). In cats (Carpenter et al 1958;McMasters and Russell 1958;Hendry et al 1979;Sugimoto et al 1981;Royce et al 1991;Ilinsky and Kultas-Ilinsky 1984) and primates (Kusama et al 1971;Chan-Palay 1977;Percheron 1977;Rouiller et al 1994;Sakai et al 1996Sakai et al , 2000, similar evidence points towards CM. Since no CM is defined in rats, such observations indicate that Pf constitutes equivalent connectivities and functions.…”

“…Similarly, these two structures seem to interact in the reticular formation (ShammahLagnado et al 1983(ShammahLagnado et al , 1987(ShammahLagnado et al , 1992Schneider et al 1985) and the nucleus of Darkschewitsch, which has been associated with the red nucleus based on its similar connectivity patterns (Onodera and Hicks 2009, 1998. The involved nuclei in the thalamus-that is, MDpl and CM/Pf-receive input from all structures mentioned here in the context of the assumed oculomotor network (Ono and Niimi 1986;Royce et al 1991;MacLeod and James 1984) and project to the frontal eye fields (Sadikot and Rymar 2009;Tanaka and Kunimatsu 2011). Furthermore, monosynaptic projections arising in SN pars compacta and the ventral tegmental area have been shown to project to the vermis of the cerebellum, which is associated with oculomotor function (Ikai et al 1992;Melchitzky 2000).…”

“…1, 2 and 3 in Mai and Forutan (2012)]. Retrograde tracing studies in CM/Pf (Royce et al 1991), Pc, and CL (Anderson and DeVito 1987;Niimi et al 1990), as well as MD (Ono and Niimi 1986; Anderson and DeVito 1987) support these observations. Projections arising from SNr and GPi were always found to be stronger than those from the cerebellum.…”

“…It is possible that certain anterograde tracers employed are not sufficiently sensitive to reveal such filigree structures. Various tracer substances do differ substantially in this regard (Royce et al 1991). Since the presented anterograde investigations were conducted inter-individually, and no intra-individual comparison via multi tracer approach is available, it is not possible to reach a final conclusion regarding the existence of overlap in MD and IL of cats.…”

An Essential Role for Frizzled5 in Neuronal Survival in the Parafascicular Nucleus of the Thalamus

“…The PFN also projects to the motor and anterior cingulate cortices (Vercelli et al, 2003;Parent and Parent, 2005). The PFN receives inputs from the spinal cord, the superior colliculus, the pedunculopontine tegmental nucleus, various vestibular nuclei, and the substantia nigra pars reticulata (Royce et al, 1991;Shiroyama et al, 1995;Kobayashi and Nakamura, 2003;Nakamura et al, 2006). The functions of the PFN are still only partially understood: it has been implicated in the response to pain (Kaelber et al, 1975;Harte et al, 2000Harte et al, , 2004Harte et al, , 2005Weigel and Krauss, 2004;Saade et al, 2007), in attentiondependent orientation (Minamimoto and Kimura, 2002), and in memory in the context of an odor discrimination task (QuirozPadilla et al, 2007).…”