The thalamo-caudate versus thalamo-cortical projections as studied in the cat with fluorescent retrograde double labeling

Abstract

The distribution of thalamic cells projecting to the head of the caudate and their interrelations with thalamo-cortical cells were studied in the cat with different combinations of fluorescent tracers. Injections in the head of the caudate were combined with the injections in the pericruciate, proreal, suprasylvian, anterior cingulate, occipital and ectosylvian cortices. The following results were obtained: (i) Injections in the head of the caudate resulted in retrograde labeling of thalamic cells medially and laterally to the anteromedial (AM) nucleus, and in the medioventral part of the ventral anterior (VA) nucleus. Further, labeled cells were distributed throughout the anterior intralaminar central medial (CeM), paracentral (Pc) and central lateral (CL) nuclei, and the posterior intralaminar center median-parafascicular complex (CM-Pf). Labeled cells were mainly grouped in the mediodorsal parts of the anterior intralaminar nuclei; they were also found in the more dorsal part of the mediodorsal (MD) nucleus, ventral to the thalamic paraventricular (Pv) nucleus and to the habenular complex. (ii) Thalamo-cortical and thalamo-caudate cells overlapped in the medial part of the VA; in the anterior intralaminar nuclei they were either intermingled or were distributed in separate clusters or longitudinal bands. The two cell populations also overlapped in the posterior intralaminar complex. The greatest overlap occurred with the thalamic cell population projecting to the pericruciate cortex. (iii) Thalamic cells bifurcating to the head of the caudate and to the pericruciate cortex were found lateral to the AM, within the VA, and throughout the anterior intralaminar nuclei, especially in the CeM and in the posterior part of the CL; a few branched cells were also found in the CM. Thalamic cells bifurcating to caudate and anterior suprasylvian cortex were also found in the VA. Very few cells (scattered in the anterior thalamus lateral to the AM, as well as in the CeM, Pc and CL) were found to bifurcate to the head of the caudate and the other cortical fields here examined.

Functional neuroimaging of normal human sleep by positron emission tomography

“…For these reasons, we cautiously suggested that these deactivations might re¯ect the eects of frontal and thalamic activity on the basal ganglia (Maquet et al 1997). Frontal cortex (Selemon and Goldman-Rakic 1985) and intralaminar thalamic nuclei (Macchi et al 1984;Sadikot et al 1990) represent the major sources of aerents to basal ganglia. They are also among the most deactivated brain areas (see related discussions).…”

Thalamic interaction between the input and the output systems of the basal ganglia

“…These projections to the striatum were confirmed by means of more modern tracing techniques, and additional thalamic projections have been also demonstrated. Thus, projections from the midline thalamic nuclei (paraventricular, paratenial, rhomboid and reuniens nuclei), the mediodorsal nucleus, the rostral nuclei of the ventral group and occasional projections from the lateral and posterior thalamic groups have been reported (Jones and Leavitt, 1974;Nauta et al, 1974;Royce, 1978;Sato et al, 1979;van der Kooy, 1979;Veening et al, 1980;Beckstead, 1984a,b;Macchi et al, 1984;Jayaraman, 1985;Philipson and Griffiths, 1985;Smith and Parent, 1986;Berendse and Groenewegen, 1990;Nakano et al, 1990;Giménez-Amaya et al, 1995;de las Heras et al, 1997de las Heras et al, , 1998ade las Heras et al, ,b, 1999.…”

Relationships between thalamostriatal neurons and pedunculopontine projections to the thalamus: a neuroanatomical tract-tracing study in the rat

“…Second, we also do not know whether they are collateral fibers of those connecting with thalamocortical neurons. Although there has been some controversy regarding this point (Steriade and Glenn 1982;Royce 1983;Macchi et al 1984;Cesaro et al 1985), there is a growing body of evidence that suggests that thalamostriatal neurons send collaterals to the cortex. Anterograde and retrograde studies in the rat have found some neurons in the PF, and PV thalamic nuclei send collaterals to the cortex as well as to various components of the basal ganglia (Deschênes et al 1996;Otake and Nakamura 1998).…”