Histochemical and architectonic differentiation of zones of pretectal and collicular inputs to the pulvinar and dorsal lateral geniculate nuclei in the macaque

Abstract

The pattern of acetylcholinesterase (AChE) reactivity was studied in the pulvinar and dorsal lateral geniculate nucleus (DLG) of the adult macaque monkey. Discrete islands of AChE reactivity were found that correlated precisely in location with the pattern of projections from the superior colliculus and pretectum. Specifically, AChE overlies terminal fields of superior colliculus projections in the DLG, in four foci in the medial and lateral pulvinar, and in several foci in the inferior pulvinar. All of these tectal projection areas have very high AChE reactivity such that they are easily distinguished. In addition, the pretectum projects to a specific focus in the lateral pulvinar that also has a very dense AChE histochemical reaction. A number of these AChE foci could be further distinguished from other areas in the pulvinar by myeloarchitectonic characteristics. Some of the foci in the lateral and inferior pulvinars could also be distinguished by unique cytoarchitectonic features (as seen with both Nissl and Golgi stains). In an attempt to determine the possible origin of a cholinergic input to the pulvinar, horseradish peroxidase (HRP) injections and choline acetyltransferase immunohistochemistry were also done. The results of this experiment indicate that the AChE reactivity seen in the midbrain projection zones to the thalamus may be due to the precise overlap of terminal projections from the brainstem cholinergic cell groups, Ch5, Ch6, and Ch8. These results, taken together, imply that there are several anatomically and histochemically distinct zones related to extrageniculate pathways located within classically defined thalamic boundaries.

Neurochemical and connectional organization of the dorsal pulvinar complex in monkeys

“…This is supported by the previous suggestion that the PLd region corresponds specifically to a zone of pretectal inputs (Lysakowski et al, 1986). Furthermore, based on its location, PMl may partly correspond to the physiologically defined dorsomedial pulvinar, Pdm (Petersen et al, 1985;Robinson et al, 1986), in which a substantial proportion of neurons showed spatially selective attentional enhancement of visual responses.…”

“…In the present parcellation, therefore, the designation PLd is used to denote a distinct triangular region of AChE stain in the nonretinotopically organized dorsal sector of classical PL. It appears to correspond to what has alternatively been regarded as "dorsolateral PL" (Lysakowski et al, 1986) or a caudal extension of the LP nucleus (Trojanowski and Jacobson, 1974;Asanuma et al, 1985;Baleydier and Mauguière, 1987;Baleydier and Morel, 1992). Because major connections of the LP nucleus are with somatosensory area 5 (Jones et al, 1979;Pons and Kaas, 1985;Yeterian and Pandya, 1985;Acuñ a et al, 1990), the present parcellation follows the more traditional designation of this region as PL rather than LP.…”

“…The present parcellation uses the term PLd rather than LP to refer to this distinct dorsolateral region because major affiliations of LP appear to be with somatosensory area 5 (Jones et al, 1979;Pons and Kaas, 1985;Yeterian and Pandya, 1985;Acuñ a et al, 1990). In addition, a previous histochemical study described a similar triangular, AChE-rich zone as a dorsolateral component of PL (Lysakowski et al, 1986). The remainder of the dorsal pulvinar, corresponding to the major part of the traditional PM nucleus, is referred to as "PM" (Fig.…”

Neurochemical organization of inferior pulvinar complex in squirrel monkeys and macaques revealed by acetylcholinesterase histochemistry, calbindin and Cat-301 immunostaining, andWisteria floribunda agglutinin binding

“…The PI complex contains chemoarchitectonic subdivisions and separate retinotopically organized zones (Bender, 1981), but appears to be tied together as a whole by connections with striate and near extrastriate cortex (Benevento and Rezak, 1976;Ogren and Hendrickson, 1976;Benevento and Davis, 1977;Graham, 1982;Maunsell and Van Essen, 1983;Ungerleider et al, 1983Ungerleider et al, , 1984Lysakowski et al, 1986;Yeterian and Pandya, 1989Baleydier and Morel, 1992;Boussaoud et al, 1992;Baizer et al, 1993;Steele and Weller, 1993;Rockland, 1996Rockland, , 1998Gutierrez and Cusick, 1997). Previous studies suggest at least two visuotopic maps in the PI complex (Bender, 1981), and projections from V1 suggest the medial, central, lateral, and lateral-shell subdivisions may contain separate representations (Gutierrez and Cusick, 1997).…”

Convergence and branching patterns of round, type 2 corticopulvinar axons

“…This could be important for priming or potentiation effects (Nowak and Bullier, 1997) or for achieving precise timing or synchronization of input to the multiple-target struc- tures (Bullier and Kennedy, 1987;Paré and Smith, 1996). It would be interesting to know whether branched corticopulvinar axons are part of an interconnected triad, i.e., does a cortical axon have collateral terminations in parts of the SC and pulvinar that are themselves interconnected by colliculopulvinar terminations (Benevento and Fallon, 1975;Lysakowski et al, 1986)? These might be reinforcing direct and indirect connections, such as seem to occur in corticocortical systems (Nakamura et al, 1993).…”