Midbrain connections of the olivary pretectal nucleus in the marmoset (<Emphasis Type="Italic">Callithrix jacchus</Emphasis>): implications for the pupil light reflex pathway

Midbrain projections of the pretectal olivary nucleus (PON) were studied in the marmoset, a New World primate. The fluorescent retrograde tracers Fluoro-Gold (FG) and Fast Blue (FB) were injected into the Edinger-Westphal (EW) nucleus and the lateral terminal nucleus (LTN), respectively. EW nucleus injections resulted in retrograde labeling of significant numbers of FG-positive neurons of the PON as well as a small number of cells in the LTN. LTN injections led to labeling of a population of singly-labeled cells seen dispersed through the larger population of FG-labeled somata within the contralateral PON. The ipsilateral PON was devoid of FB-labeled somata, whereas the adjacent nucleus of the optic tract (NOT) contained FB-labeled cells. These findings show that a large number of PON neurons project directly to the oculomotor complex. Additionally, the study shows the presence of a separate population of PON neurons projecting to the contralateral LTN. This, combined with our earlier observation that LTN neurons project to the EW nucleus in the marmoset (see main text for reference), lends support to the presence of separate direct and indirect pupillary light reflex pathways from the PON to the nucleus of EW.     

Luminance neurons in the pretectal olivary nucleus mediate the pupillary light reflex in the rhesus monkey

In humans and other primates, an increase in luminance in either eye elicits bilateral pupilloconstriction that is essentially equal in both eyes. Current models of the neural substrate for this clinically important light reflex propose that a retinorecipient pretectal nucleus projects bilaterally to the Edinger-Westphal nucleus (EW), which contains the parasympathetic, preganglionic neurons controlling pupilloconstriction. Based on single-unit recording studies in anesthetized cats and rats, it has been further suggested that luminance neurons in only one pretectal nucleus, the pretectal olivary nucleus, mediate this reflex. However, to our knowledge, there have been no comparable electrophysiological studies in primates of the pupillary light reflex or the pretectal luminance neurons that mediate this reflex. To address this issue, single-unit recording and electrical microstimulation studies were carried out in the pretectum of alert, trained, rhesus monkeys. These studies demonstrated that the primate pretectum contains luminance neurons with the characteristics appropriate for mediating the pupillary light reflex and that these neurons are located in one retinorecipient pretectal nucleus, the pretectal olivary nucleus. Electrical microstimulation at the site of these neurons often elicited pupilloconstriction. Our results provide clear evidence for the involvement of the pretectum, and more specifically the pretectal olivary nucleus, in mediating the pupillary light reflex in primates.     

The topology of the thalamo-cortical projections in the marmoset monkey (Callithrix jacchus)

Summary This paper addresses the question of a general topological principle of thalamo-cortical projections. In the lissencephalic primate brain of the common marmoset (Callithrix jacchus), large injections of horseradish peroxidase were made in various parts of the neocortex. These injections were placed in different animals and hemispheres along various caudo-rostral and mediolateral gradients. Labelled cells in the thalamus were plotted and the labelling-zones resulting from several injections along a medio-lateral and two caudo-rostral cortical vectors were drawn into semi-schematic thalamic maps. These composite maps reveal a topological organization of the whole thalamo-cortical projection. The thalamic representation of the caudo-rostral and mediolateral gradients indicate a rotation of the posterior relative to the anterior thalamus. An attempt is made to relate the organization of the thalamo-cortical projection to the development of the thalamus and the cortex. The cortex is divided into concentric zones around the sensory-motor and insular cortex. The thalamus is divided into corresponding projection zones. The topology of thalamo-cortical connections can then be regarded as a consequence of corresponding thalamic and cortical growth gradients. This is not only consistent with the general thalamo-cortical topology and the inversion of maps from thalamus to cortex, but also explains the continuity and overlap of thalamic projection zones in the pulvinar to widely separated cortical areas as the parietal, temporal and frontal association cortex.Abbreviations AD Nucleus anterior dorsalis thalami - AM Nucleus anterior medialis thalami - AV Nucleus anterior ventralis thalami - CeD Nucleus centralis dorsalis thalami - CeL Nucleus centralis lateralis thalami - CeM Nucleus centralis medialis thalami - CeMe Centre median - GLD Corpus geniculaturn laterale dorsale - GLV Corpus geniculatum laterale ventrale - GM Corpus geniculatum mediale - LD Nucleus lateralis dorsalis thalami - Li Nucleus limitans thalami - LP Nucleus lateralis posterior thalami - MD Nucleus medialis dorsalis thalami - Pf Nucleus parafascicularis thalami - PvT Nucleus paraventricularis thalami - Pul Pulvinar inferior - PuIP Pulvinar inferior posterior - PuL Pulvinar lateralis - PuM Pulvinar medialis - PuO Pulvinar oralis - Re Nucleus Reuniens - Sg Nucleus suprageniculatus - VA Nucleus ventralis anterior - VAMg Nucleus ventralis anterior magnocellularis - VL Nucleus ventralis lateralis - VP Nucleus ventralis posterior - VPL Nucleus ventralis posterior lateralis - VPM Nucleus ventralis posterior medialis     

The local domain for divergence of subcortical afferents to the striate and extrastriate visual cortex in the common marmoset (Callithrix jacchus): a multiple labelling study

Summary In the common marmoset (Callithrix jacchus), the cortical projection from the pulvinar and other diencephalic structures into the striate and prestriate cortex was investigated with various fluorescent retrograde tracers. Single cortical injections as well as multiple injections at distances of 1–2 mm with one tracer into an extended but coherent cortical region were applied. Fields with multiple injections were placed so that they touched each other (minimal distances 2 to 3 mm). Retrogradely labelled cells in the LGN and/or the pulvinar were arranged in coherent columns, volumes or slabs, but cell volumes resulting from neighbouring cortical injections overlapped at their border (for details of the thalamo-cortical topography see the companion paper Dick et al. (1991)). Double labelled cells (dl) were only found in the zones of overlap of the cell volumes labelled by the respective tracers. The relative number of dl-cells in these overlap zones was 6.2 ± 3.1%. The dl-frequency was the same in the various nuclei of the pulvinar and the LGN. In the main layers of LGN, dl-cells were found only in the overlap zone of two injection fields into area 17, but a few dl-cells were found in interlaminar cells after injections into area 17 and 18. Maximal cortical distances between injection fields which produced dl in the pulvinar, were 3 to exceptionally 4 mm but dl was highest at injection distances 2.5 mm and decreased sharply at wider distances. Such overlap zones were concerned with identical or overlapping regions of visual field representation in the cortex and probably also in the pulvinar. Although in individual experiments up to four different tracers were injected into different striate/prestriate regions, often embracing the same visual field representation, individual cells in the pulvinar showed dl from maximally only two tracers injected into neighbouring cortical regions. We conclude that dl in the posterior thalamic projection nuclei is determined essentially by cortical distance and thus reflects the local domain of branching of thalamo-cortical afferents. Pruning of such branches during development may further restrict bifurcating axons to identical visual field representations, but representation of identical visual field regions in different visual areas is not, per se, a sufficient condition for dl. It is not found if such regions are further apart from each other than the typical local domain of 2–3 mm, exceptionally up to 4 mm in one experiment after injections into area 17 and MT. Dl in the intralaminar nucleus CeL (5.0 ± 4.6%), the claustrum (5.4 ± 3.6%) and in the amygdala (5.7 ± 1.9%) was of the same order as in the pulvinar and LGN. In the hypothalamus around 10% and in the Nucleus basalis Meynert 15.8% of the cells labelled by visual cortical injections were double labelled. In all these extrathalamic regions dl was also restricted to overlap zones, but overlap of labelled fields in these nuclei was much wider and included the whole striate/prestriate cortex except for some topographical separation of striate and prestriate projection zones in the claustrum. Only in the Nucl. basalis Meynert and the hypothalamus some cells were labelled by three tracers.     

Topographically organized reciprocal connections between areas 17 and MT (visual area of superior temporal sulcus) in the marmoset Callithrix jacchus

Summary With the aid of the techniques of tracing axonal pathways by anterograde fiber degeneration, and by anterograde (autoradiography) and retrograde (HRP-histochemistry) axoplasmic transport, it could be shown that area 17 projects in a topographically and visuotopically organized manner onto the temporal visual area MT. The fibers of this association system originate from pyramidal cells in layer IIIc, and from the solitary cells of Meynert; they terminate in layers IV and III of area MT. A correspondingly organized system of countercurrent fibers originates from pyramidal cells in layers III/II and V/VI of area MT and terminates separately in layers VI, IIIc and I of area 17.     

Relation of single unit properties to the oculomotor function of the nucleus of the basal optic root (accessory optic system) in chickens

Summary Single unit recordings in the nucleus of the basal optic root (nBOR) of the accessory optic system in chickens suggest that it has a role in vertical stabilizing eye movements. Cells have unusually large receptive fields and never respond to small stationary stimuli. They respond best to large richly patterned stimuli moving slowly (2–4 °/s) in vertical directions. Cells responsive to upward movement tend to be located in the dorsal portion of nBOR, which projects to motor areas producing upward eye movement, whereas cells responsive to downward movement tend to be located in the ventral portion of nBOR, which projects to motor areas producing downward eye movement; this suggests that these synapses onto oculomotor neurons are excitatory.In many nBOR units, the preferred and null directions are not opposite to each other. These directional asymmetries seem to be correlated with other properties of the units in a manner that supports the idea that the accessory optic system is arranged according to a vestibular coordinate system. This finding complements the abundant anatomical and physiological evidence linking the accessory optic system to the vestibular system.This work was supported by a research grant from the National Eye Institute, EY02937     

Afferents of the caudal fastigial nucleus in a New World monkey (Cebus apella)

Summary The afferents of the fastigial nucleus (FN) were studied in two capuchin monkeys (Cebus apella) one of which had received a unilateral injection of horseradish peroxidase in the caudal FN, and a second monkey which received a control injection that involved the lateral caudal FN but extended into the cerebellar white matter between the FN and posterior interposed nucleus (PIN). All of the sources of FN afferents were found to be labeled bilaterally. In addition to the restricted distribution of labeled Purkinje cells in lobules VI and VII of the posterior lobe vermis (oculomotor vermis), retrogradely labeled cells were present in the dorsolateral pontine nucleus (DLPN), dorsomedial pontine nucleus (DMPN), nucleus reticularis tegmenti pontis (NRTP), pontine raphe (PR), paramedian nucleus reticularis pontis caudalis (NRPC), nucleus prepositus hypoglossi (NPH), subnucleus b of the medial accessory olivary nucleus (sbMAO), and vestibular complex (VC). The second (control) injection appeared to confirm a proposed (Langer et al. 1985b) projection from the flocculus to the basal interstitial nucleus. The results are discussed in terms of the functional relationships of the FN to the frontal eye field and oculomotor-related brainstem structures involved in the production of saccadic and smooth pursuit eye movements.Abbreviations AIN anterior interposed nucleus, cerebellum - BC brachium conjunctivum (sup. cerebellar peduncle) - BIN basal interstitial nucleus, cerebellum - BPN basilar pontine nuclei - CS corticospinal (pyramidal) tract - DBC decussation of brachium conjunctivum - DLPN dorsolateral pontine nucleus (Nyby and Jansen 1951) - DMPN dorsolateral pontine nucleus - DN dentate nucleus, cerebellum - DNV descending nucleus of the trigeminal complex (C.N. V) - FN fastigial nucleus, cerebellum - IC inferior colliculus - ICP inferior cerebellar peduncle - IVN inferior vestibular nucleus - LCN lateral (external) cuneate nucleus - LPN lateral pontine nucleus - MAO medial accessory nucleus of the inferior olivary complex - ML medial lemniscus - MLF medial longitudinal fasciculus - MRF medullary reticular formation (nuc. retic. gigantocellularis) - MVN medial vestibular nucleus - NI nucleus intercalatus of Staderini of the perihypoglossal complex - NPH nucleus prepositus hypoglossi - NRPC nucleus reticularis pontis caudalis - NRPO nucleus reticularis pontis oralis - NRTP nucleus reticularis tegmenti pontis - PIN posterior interposed nucleus - PR pontine raphe - sbMAO subnucleus b, medial accessory olivary nucleus - SC superior colliculus - sbPVG supragenial peri- (IVth) ventricular gray - SVN superior vestibular nucleus - VIn abducens nerve (C.N. VI) - XIIn hypoglossal nerve (C.N. XII)     

Collateralization of cerebellar efferent projections to the paraoculomotor region,superior colliculus,and medial pontine reticular formation in the rat: a fluorescent double-labeling study

Summary Collateralization of cerebellar efferent projections to the oculomotor region, superior colliculus (SC), and medial pontine reticular formation (mPRF) was studied in rats using fluorescent tracer substances. In one group, True Blue (TB) was injected into the oculomotor complex (OMC), including certain paraoculomotor nuclei and supraoculomotor ventral periaqueductal gray (PAG), and Diamidino Yellow (DY) was injected into the medial pontine reticular formation (mPRF) or pontine raphe. The largest number of single-TB-labeled (paraoculomotor-projecting) cells was observed in the medial cerebellar nucleus (MCN) and posterior interposed nucleus (PIN), whereas the largest number of single-DY-labeled (mPRF-projecting) cells was in the MCN. Double-TB/DY-labeled cells were present in the caudal two-thirds of the MCN, suggesting that some MCN neurons send divergent axon collaterals to the paraoculomotor region and mPRF. In another group, TB was injected into the SC and DY into the mPRF. The largest number of single-TB-labeled (SC-projecting) cells was in the PIN, although a considerable number of cells was observed in the caudal MCN, and ventral lateral cerebellar nucleus (LCN). Single-DY-labeled (mPRF-projecting) neurons were primarily located in the central and ventral MCN, but were also present in the lateral anterior interposed (AIN) and in the LCN. Double-TB/DY-labeled neurons were observed in the caudal two-thirds of the MCN and in the central portion of the LCN. The most significant new findings of the study concerned the MCN, which not only contained neurons that projected independently to the paraoculomotor region, SC, and mPRF, but also contained a considerable number of cells which collateralized to project to more than one of these nuclei. The possibility that the MCN projects to the supraoculomotor ventral PAG (containing an oculomotor interneuron system) and to the mPRF, which in the cat and monkey contain neural elements essential to the production of saccadic eye movements, is discussed. The anatomical findings suggest that the MCN in the rat plays an important role in eye movement.Abbreviations AI anterior interposed nucleus - AIN anterior interposed nucleus - BC brachium conjunctivum (sup. cerebellar peduncle) - dlh dorsolateral hump of the AI - dmc dorsomedial crest of the AI - IC inferior colliculus - ICP inferior cerebellar peduncle - Inf infracerebellar nucleus - L lateral cerebellar (dentate) nucleus - LCN lateral cerebellar (dentate) nucleus - M medial cerebellar (fastigial) nucleus - MCN medial cerebellar (fastigial) nucleus - MLF medial longitudinal fasciculus - mPRF medial pontine reticular formation (incl. nuc. reticularis pontis oralis and caudalis) - OMC oculomotor complex - OMN oculomotor nucleus - PI posterior interposed nucleus - PIN posterior interposed nucleus - RN red nucleus - SC superior colliculus - Vl lateral vestibular nucleus - Vs superior vestibular nucleus - Y cell group Y     

Collateralization of frontal eye field (medial precentral/anterior cingulate) neurons projecting to the paraoculomotor region,superior colliculus,and medial pontine reticular formation in the rat: a fluorescent double-labeling study

Summary Paired injections of fluorescent tracers (True Blue, Diamidino-Yellow) were made into the oculomotor complex (OMC) and medial pontine reticular formation (mPRF), and superior colliculus (SC) and mPRF, in adult rats to retrogradely label the cortical cells of origin of projections to these oculomotor-related brainstem structures. While large numbers of single-labeled cells in the medial frontal cortex projected only to the mPRF, the presence of many double-labeled cells in the dorsomedial shoulder cortex (medial precentral/anterior cingulate areas), the rat frontal eye field (FEF), indicated that this cortical region contains lamina V pyramid neurons whose axons collateralize to project to the region of the OMC, SC, and mPRF. The similarities of rat and monkey FEF connections, and their relevance to the control of eye movement, are discussed.Abbreviations AC anterior commissure - ACd anterior cingulate area, dorsal - ACv anterior cingulate area, ventral - AId anterior insular area, dorsal - AIv anterior insular area, ventral - BC brachium conjunctivum (superior cerebellar peduncle) - CP caudoputamen - DY Diamidino Yellow - IL infralimbic area - MAB medial accessory nucleus of Bechterew - MLF medial longitudinal fasciculus - mPRF medial pontine reticular formation - MO medial orbital area - OMC oculomotor complex - PAG periaqueductal gray - PrCl lateral precentral cortex - PrCm medial precentral cortex - PL prelimbic area - RN red nucleus - riMLF rostral interstitial nucleus of the MLF - rs rhinal sulcus - SC superior colliculus - TB True Blue - VLO ventrolateral orbital area     

Projections from the central nucleus of the amygdala to the nucleus pontis oralis in the rat: An anterograde labeling study

The present study was designed to elucidate the neuronal projections from the amygdala to the nucleus pontis oralis (NPO). We propose that glutamatergic cells in the central nucleus of the amygdala (CNA) activate neurons in the NPO, which is the critical brainstem site that is responsible for the generation and maintenance of active (REM) sleep. Phaseolus vulgaris-leucoagglutinin (PHA-L), an anterograde transported neuronal tracer, was iontophoresed into the CNA of adult male Sprague-Dawley rats. After a survival time of 7-8 days, the animals were perfused with a fixative and brain tissue was prepared for histological analysis. Sections of the NPO and CNA, which were immunostained with an antibody against PHA-L, were examined with light microscopy. In addition, in order to identify the phenotype of PHA-L-labeled fibers and terminals in the NPO, a double immunohistochemical technique was employed with antibodies against PHA-L and the vesicular glutamate transporter type 2 (VGluT2). Numerous PHA-L-labeled axons and terminals were found in the NPO ipsilateral to the injection site in the CNA. Within the NPO, the majority of labeled fibers were located in the dorsolateral portion of the caudal part of the nucleus. Double-labeling immunostaining studies revealed that PHA-L-labeled axons and terminals in the NPO were glutamatergic. The present demonstration of direct, excitatory (glutamatergic) projections from the CNA to the NPO provide an anatomical basis for the amygdalar control of active sleep.     

Ontogeny of vision in the Peking duck (Anas platyrhynchos): the pupillary light reflex as a means for investigating visual onset and development in avian embryos

The pupillary light reflex was used to determine the onset of visual function in Peking duck embryos (Anas platyrhynchos). Neurally mediated pupillary responses were first elicited on Day 18 (67% of total incubation), but 2 days prior to this and for several days during prenatal life, autonomous iris constriction was found. The neural and nonneural components of the response were separated using both an excision and a curare technique, each of which produced similar results. The pupillary technique for studying visual onset and development was further evaluated by a study of chick embryos (Gallus gallus), in which it was seen that results from this technique were in good agreement with those gleaned from more complex methods. It was concluded that the technique affords several advantages, particularly with respect to clarity of interpretation, ease of execution, and amount of information provided.     

Coexistent loss of INI1 and BRG1 expression in a rhabdoid renal cell carcinoma (RCC): implications for a possible role of SWI/SNF complex in the pathogenesis of RCC

In this study, we analyzed the immunohistochemical and molecular profiles of an unusual RCC showed coexistent absence of INI1 and BRG1 expression, rhabdoid morphology, and poor prognosis. Histologically, the tumor had rhabdoid features, which were demonstrated by large round to polygonal cells with eccentric nuclei, prominent nucleoli, and eosinophilic cytoplasm varying from abundant to scanty. Immunohistochemically, the tumor were positive for BRM, PBRM1, ARID1A, CD10, CKpan, Vimentin, carbonic anhydrase IX (CA-IX), and P504S (AMACR) but negative for INI1, BRG1, HMB45, melan A, CK7, CD117, Ksp-cadherin, TFEB, TFE3, and Cathepsin K. We detected all three exons status of the VHL gene of the tumor and observed 1 somatic mutations in 1st exon. Chromosome 3p deletion, coupled with polysomy of chromosome 3 was also found. Based on these findings, it is further indicated that in some cases, rhabdoid RCC may arise from clear cell RCC. SWI/SNF chromatin remodeling complex may be an attractive candidate for being the “second hit” in RCCs and may play an important role during tumor progression. The role of SWI/SNF complex in rhabdoid RCC should be further studied on a larger number of cases.     

Nuclear organization of cholinergic,catecholaminergic, serotonergic and orexinergic systems in the brain of the Tasmanian devil (Sarcophilus harrisii)

This study investigated the nuclear organization of four immunohistochemically identifiable neural systems (cholinergic, catecholaminergic, serotonergic and orexinergic) within the brains of three male Tasmanian devils (Sarcophilus harrisii), which had a mean brain mass of 11.6 g. We found that the nuclei generally observed for these systems in other mammalian brains were present in the brain of the Tasmanian devil. Despite this, specific differences in the nuclear organization of the cholinergic, catecholaminergic and serotonergic systems appear to carry a phylogenetic signal. In the cholinergic system, only the dorsal hypothalamic cholinergic nucleus could be observed, while an extra dorsal subdivision of the laterodorsal tegmental nucleus and cholinergic neurons within the gelatinous layer of the caudal spinal trigeminal nucleus were observed. Within the catecholaminergic system the A4 nucleus of the locus coeruleus complex was absent, as was the caudal ventrolateral serotonergic group of the serotonergic system. The organization of the orexinergic system was similar to that seen in many mammals previously studied. Overall, while showing strong similarities to the organization of these systems in other mammals, the specific differences observed in the Tasmanian devil reveal either order specific, or class specific, features of these systems. Further studies will reveal the extent of change in the nuclear organization of these systems in marsupials and how these potential changes may affect functionality.     

Nuclear organization of some immunohistochemically identifiable neural systems in two species of the Euarchontoglires: A Lagomorph,Lepus capensis,and a Scandentia,Tupaia belangeri

The present study describes the organization of the nuclei of the cholinergic, catecholaminergic, serotonergic and orexinergic systems in the brains of two members of Euarchontoglires, Lepus capensis and Tupaia belangeri. The aim of the present study was to investigate the nuclear complement of these neural systems in comparison to previous studies on Euarchontoglires and generally with other mammalian species. Brains were coronally sectioned and immunohistochemically stained with antibodies against choline acetyltransferase, tyrosine hydroxylase, serotonin and orexin-A. The majority of nuclei revealed in the current study were similar between the species investigated and to mammals generally, but certain differences in the nuclear complement highlight potential phylogenetic interrelationships within the Euarchontoglires and across mammals. In the northern tree shrew the nucleus of the trapezoid body contained neurons immunoreactive to the choline acetyltransferase antibody with some of these neurons extending into the lamellae within the superior olivary nuclear complex (SON). The cholinergic nature of the neurons of this nucleus, and the extension of cholinergic neurons into the SON, has not been noted in any mammal studied to date. In addition, cholinergic neurons forming the medullary tegmental field were also present in the northern tree shrew. Regarding the catecholaminergic system, the cape hare presented with the rodent specific rostral dorsal midline medullary nucleus (C3), and the northern tree shrew lacked both the ventral and dorsal divisions of the anterior hypothalamic group (A15v and A15d). Both species were lacking the primate/megachiropteran specific compact portion of the locus coeruleus complex (A6c). The nuclei of the serotonergic and orexinergic systems of both species were similar to those seen across most Eutherian mammals. Our results lend support to the monophyly of the Glires, and more broadly suggest that the megachiropterans are more closely related to the primates than are any other members of Euarchontoglires studied to date.