Medial Extension Research Articles

Expression of MAP1a and MAP1b in the ganglionic eminence and the internal capsule of the human fetal brain.

The expression of microtubule-associated proteins 1a and 1b (MAP1a and 1b) were investigated in two transient structures, the ganglionic eminence (GE) being a prominent part of the telencephalic proliferative zone and the perireticular nucleus (PR) within the internal capsule (IC). Anti-MAP1a immunolabels PR neurons from 18 weeks of gestation (wg) onwards, whereas anti-MAP1b immunolabels long IC fibers between 18 and 22 wg. MAP1b is further present in thalamic fibers that seem to terminate at the medial margin of the GE, in a moderate number of cells of the GE and its medial extension, the gangliothalamic body (GTB). From 26 to 33 wg MAP1b is expressed in short fiber bundles of the IC, a few MAP1b-positive cells are seen in the GE. MAP1a has so far been described to appear in differentiated neurons and to be related to late developmental events. However, the transient PR being involved in axonal guidance as an intermediate target shows a precocious MAP1a-expression. The MAP1b-finding that thalamocortical fibers accumulate at the GE-margin indicates that this region represents an intermediate target for these fibers. The short MAP1b fiber bundles found in the IC are in accordance with cell culture experiments showing that MAP1b is concentrated in distal parts of outgrowing axons.

Experiences with transconjunctival upper blepharoplasty.

Upper blepharoplasty remains a valuable procedure in rejuvenating the upper eyelid. An innovative technique was recently reported whereby medial fat is removed through a transconjunctival approach. This is a preliminary report of our experience with 60 patients treated over the past 10 months using this technique. The technique will be described in detail and cases will be reported. There were no perioperative or postoperative complications. All of the patients are satisfied with the results of their surgical procedure. The technique has the advantage of avoiding an incision of the medial upper eyelid and the inherent risks of excessive scarring in this area. We have found the technique especially useful in secondary blepharoplasty with an isolated prominence of residual medial fat. Other advantages include the following: primary cases in which the surgeon is able to avoid medial extension of the cutaneous incision, patients who possess deep tarsal folds with prominent medial fat, or as an adjunct to eyebrow lifting techniques where in both cases cutaneous excision is unnecessary. No disadvantages have been noted.

Organization of connections of the basal and accessory basal nuclei in the monkey amygdala.

The present study investigated the intrinsic connections of the basal and accessory basal nuclei of the Macaca fascicularis monkey by means of the anterograde tracers Phaseolus vulgaris-leucoagglutinin (PHA-L) and biotinylated dextran amine (BDA). Analysis of the intranuclear connections of the basal nucleus indicates that there are five modules: dorsal, intermediate, ventral lateral, ventral medial and periamygdaloid sulcal cortex. The dorsal division projects to the intermediate division. Laterally, the intermediate division projects to the ventral lateral division and dorsal parts of the ventral medial division. Ventrally, the ventral lateral division projects to the ventral medial division and periamygdaloid sulcal cortex, which appears to constitute a medial extension of the basal nucleus onto the cortical surface of the amygdala. Medially, the ventral medial division projects to the intermediate and dorsal divisions. Thus, the connections between these modules form functional microcolumns within the nucleus with distinct patterns of information flow that are dorsal to ventral laterally, lateral to medial ventrally, and ventral to dorsal medially. Observations on the intranuclear connections of the accessory basal nucleus suggest that they are organized into two relatively distinct domains: the dorsal division projects to the ventral division and the ventral division projects primarily to the ventromedial division. Projections to other amygdaloid areas originate in select divisions of the basal and accessory basal nuclei, and are topographically distributed. The organization of intrinsic connections of the basal nuclei correlates with specific amygdalo-cortical connections and suggests that extensive convergence of information takes place within the amygdala, which potentially influences activity at both the temporal and parietal pathways and hippocampal fields.

Reorganization of vibrissal motor representation following severing and repair of the facial nerve in adult rats.

This study examined the ability of adult rat motor cortex to reorganize its relationship with the somatic musculature following the severing and regeneration of a motor nerve. For this purpose experiments were performed on ten male albino rats where the facial nerve on one side was severed, sutured and allowed to regenerate for 6 months. Cortical motor output organization was assessed by mapping the vibrissal movement area extension and thresholds evoked by intracortical electrical stimulation in anesthetized rats. In all ten animals, the cortical output pattern of the motor cortex contralateral to the normal side was compared with that contralateral to the reinnervated side. After facial nerve reinnervation, the most notable differences in primary motor cortex (M1) output organization in the hemispheres contralateral to the reinnervated side were: (a) the area from which vibrissa movements could be evoked at low thresholds was smaller (mean 1.2+/-0.38 mm, range 0.75-1.75 mm), decreasing to 64.2% below those in hemispheres contralateral to the normal side (mean 3.4+/-0.52 mm, range 2.5-4 mm). The reorganized vibrissa area consisted of contiguous or discontinuous points shrunken to the medialmost portion of normal M1 vibrissal representation. (b) There was a clear medial extension of the forelimb representation, and a more modest lateral expansion of eye representation, into the vibrissa territory. The mean threshold required to evoke vibrissa movements was significantly higher in the hemispheres contralateral to the reinnervated side than in the other hemispheres (normal 23.9+/-9.7 microA vs reinnervated 37.8+/-11.9 microA; P< or =0.0001; t-test). The stimulation currents required to evoke other types of body movements were similar in the normal and reinnervated sides. Similar results were observed in all rats. In conclusion, these results indicate that motor nerve reinnervation is sufficient to produce long-lasting changes at a higher motor cortical level. This supports the notion that central supranuclear mechanisms may also be involved in the disorder of facial movements observed after facial nerve reinnervation.

The preoptic area/anterior hypothalamus of different strains of mice: sex differences and development

While sex differences in neural morphology in the preoptic area/anterior hypothalamus (POA/AH) have been demonstrated in many species, their existence in mice have been controversial. Given the increased use of transgenic and gene-disrupted mice, we characterized sex differences using Nissl stains, and the immunocytochemical location of estrogen receptor-α (ER-α) and galanin in the POA/AH of two widely used strains, C57BL/6 and 129SvEv, and a mixed strain (C57BL/6×129Sv); the wild-type littermates of steroidogenic factor-1 (SF-1) gene-disrupted mice. Cell grouping was not a reliable marker of sex. In adults, cells located beneath the anterior commissure (AC) were reliably larger in females than males in 129SvEv, but not in the other strains. Caudally, cells in a group medial to the medial extension of the bed nucleus of the stria terminalis (BST) were significantly larger in males than females in C57BL/6J and SF-1 gene-disrupted wild-types. Cell groups discernible by embryonic day (E) 18 were not sexually dimorphic for cell size in C57BL/6J mice at E18 or postnatal day (P) 4. The pattern of distribution of cells containing ER-α was similar among the strains, reduced in the group medial to the BST; a pattern established by P0. Galanin-containing cells and fibers were seen from E15 to adulthood ventral to the AC. Caudally, a smaller group ventromedial to the BST was found only in 129SvEv adults. Sex differences in neural morphology which develop within the POA/AH depend upon multiple factors, particularly including genetic background.

Fiber system linking the mid-dorsolateral frontal cortex with the retrosplenial/presubicular region in the rhesus monkey

The present study investigated the origin, course, and terminations of the association fiber system linking the frontal cortex with the hippocampal system by means of the cingulum bundle. Injections of tritiated amino acids were placed within individual cytoarchitectonic areas of the frontal cortex in the rhesus monkey. It was demonstrated that the mid-dorsolateral frontal cortex (areas 46, 9/46, and 9) and its medial extension (medial areas 9 and 9/32) is the origin of a specific fiber pathway, running posteriorly as part of the cingulum bundle, and terminating mainly in the retrosplenial area 30 and the posterior presubiculum. This fiber bundle therefore provides the anatomical substrate of a functional interaction between the mid-dorsolateral frontal cortex and the hippocampal memory system for the monitoring of information within working memory.

Simultaneous malaroplasty with porous polyethylene implants and orthognathic surgery for correction of malar deficiency.

Patients with skeletal malrelationships caused by maxillary anteroposterior defect and midface hypoplasia may present with an alteration of cheekbone contour. High osteotomies, segmental osteotomies of the zygomatic complex, and malar expansion with alloplastic materials can be performed to improve facial aesthetics. This article describes the restoration of cheekbone-nasal base-lip contour by performing a malaroplasty using an alloplastic implant in addition to orthognathic surgery. From 1995 to 1996, 17 patients with maxillomandibular malrelationships and deficient cheekbone contour were tested by malar augmentation with porous high-density polyethylene in association with maxillary advancement and mandibular setback. The diagnosis of cheekbone contour alteration was made after observing the patient from a lateral, frontal, and oblique point of view. The position of the implant was determined by using Mladick's point, with lateral or medial extension in relation to the depressed area. By the restoration of normal cheekbone-nasal base-upper lip contour produced excellent aesthetic results in all patients. Malaroplasty in association with bimaxillary orthognathic surgery seems to be an effective procedure for treating midface skeletal deficiencies.

Miocene Paleogeography of Southwestern California and Its Implications Regarding Basin Terminology

A new palinspastic reconstruction for the latest Oligocene of southwestern California is created by: (1) backsliding the eastern part of the western Transverse Ranges west of the curved San Gabriel-Sierra Madre fault in a counterclockwise, rotational, left-slip direction in order to close the gap created by medial Miocene transrotational extension of the easternmost Los Angeles basin; and (2) bending the rocks in the westernmost Transverse Ranges, west of the Santa Monica Mountains, through an additional counterclockwise backrotation until they are in contact with the present southern California coast. This reconstruction restores Eocene forearc basin deposits of the southern California coast and the western Transverse Ranges regions into straight alignment with Eocene forearc-basin deposits to the north in the San Rafael Mountains. During the Oligocene, this forearc basin was divided into two depositional basins that received mostly nonmarine deposits. The northern of the two basins is named the DiSoCuMa depositional basin and the southern one the AnaVent depositional basin. Subsidence occurred during the early Miocene and flooded the two basins with marine deposits. During the medial Miocene, subsidence continued as the western side of the AnaVent basin (today's western Transverse Ranges) began to pull away from the southern California coast and rotate clockwise around its northern end. This transrotational process served to enlarge both basins by crustal extension and produced extensive areas of volcanism. Throughout the late Miocene, transrotation and subsidence continued, the basins grew in size and depth to their present configuration, and internal isostatic adjustments produced several new marine depositional basins within the previous two-basin framework.

Convergence of somatosensory and auditory projections in the avian torus semicircularis, including the central auditory nucleus.

Projections of dorsal column, spinal, and cochlear nuclei upon the central nucleus of the torus semicircularis (otherwise known as nucleus mesencephalicus lateralis, pars dorsalis, or MLd) and upon other toral nuclei were investigated in pigeon by anterograde and retrograde tracing and electrophysiological methods. The anatomical results showed that caudal regions of the dorsal column nuclei and medial lamina V of the upper four cervical spinal segments have extensive projections upon the contralateral central auditory nucleus and upon other nuclei of the torus, in particular the core portion of the preisthmic superficial area of Puelles et al. (L. Puelles, C. Rrobles, M. Martiez-de-la-Torre, and S. Martinez, 1994, J. Comp. Neurol. 340:98-125). The projections of nucleus angularis were found to terminate throughout most of the contralateral central nucleus except the dorsomedial portion at rostral levels, where the majority of the projections of nucleus laminaris were concentrated. Nucleus angularis (and to a lesser extent nucleus laminaris) was also found to have substantial projections to certain noncentral toral nuclei, in particular to the caudomedial shell nucleus of Puelles et al. (1994). As shown positively with both Nissl and cytochrome oxidase staining and negatively with substance P labeling, this nucleus is a medial extension of more caudal regions of the central nucleus, and it is suggested that it should be included as part of the auditory midbrain. The electrophysiological results confirmed the anatomical findings by showing that evoked potentials and multiunit activity can be recorded throughout the central and noncentral toral nuclei by using electrical stimulation of the radial nerve and auditory click stimuli. The core portion of the preisthmic superficial area, however, can be regarded as a distinct somatosensory nucleus of the midbrain. It is concluded that there is substantial convergence of somatosensory and auditory inputs within both central auditory and noncentral nuclei of the torus semicircularis in pigeon.

Alterations in vascular pattern of the developing palate in normal and spontaneous cleft palate mouse embryos.

The alterations in the vascularization of the developing palate were studied through the use of resin cast images of vascular networks in normal and spontaneous cleft lip and palate (CL/Fr) mouse embryos (crown rump [CR] Length 9-18 mm, body wt. 0.11-0.65 g). A more dense vascular plexus was observed in the oral side than in the nasal side before the reorientation of the palatal shelves. Prominent terminal dilatations of the vascular plexus were observed in the extreme medial edge of the elevating palatal shelves which may exert significant force for palatal shelf elevation. The vascular plexus showed a lateral extension. Many small spherical masses of resin were observed in the medial edge of the palatal shelves at the time of medial extension and during fusion, indicating some changes occurring in the capillary wall leading to the resin leakage. In the spontaneous cleft group, a similar vascular pattern was observed, but the greater palatine artery showed discontinuity in the premaxillary region at an early stage. At the same time, terminal dilatations were delayed and frequently absent in the contralateral shelf. After the reorientation of the palatal shelves, the vascular plexus formed an irregular lattice pattern. Dilated vasculature was apparent in the anterior nasopalatine region, indicating the persistence of a more primitive vascular structure in the spontaneous cleft embryos. However, the area where capillary dilatation occurred was different between unilateral and bilateral cleft embryos. In conclusion, blood vessels in the palatal shelves are underdeveloped and remained immature in cleft lip and palate embryos and showed different patterns in the anterior nasopalatine region between unilateral and bilateral cleft embryos. These variant vascular patterns may be due to the inadequate blood supply to the nasopalatine region from the early embryonic stages possibly resulting from the discontinuity of the greater palatine artery.

Alterations in Vascular Pattern of the Developing Palate in Normal and Spontaneous Cleft Palate Mouse Embryos

The alterations in the vascularization of the developing palate were studied through the use of resin cast images of vascular networks in normal and spontaneous cleft lip and palate (CL/Fr) mouse embryos (crown rump [CR] Length 9-18 mm, body wt. 0.11-0.65 g). A more dense vascular plexus was observed in the oral side than in the nasal side before the reorientation of the palatal shelves. Prominent terminal dilatations of the vascular plexus were observed in the extreme medial edge of the elevating palatal shelves which may exert significant force for palatal shelf elevation. The vascular plexus showed a lateral extension. Many small spherical masses of resin were observed in the medial edge of the palatal shelves at the time of medial extension and during fusion, indicating some changes occurring in the capillary wall leading to the resin leakage. In the spontaneous cleft group, a similar vascular pattern was observed, but the greater palatine artery showed discontinuity in the premaxillary region at an early stage. At the same time, terminal dilatations were delayed and frequently absent in the contralateral shelf. After the reorientation of the palatal shelves, the vascular plexus formed an irregular lattice pattern. Dilated vasculature was apparent in the anterior nasopalatine region, indicating the persistence of a more primitive vascular structure in the spontaneous cleft embryos. However, the area where capillary dilatation occurred was different between unilateral and bilateral cleft embryos. In conclusion, blood vessels in the palatal shelves are underdeveloped and remained immature in cleft lip and palate embryos and showed different patterns in the anterior nasopalatine region between unilateral and bilateral cleft embryos. These variant vascular patterns may be due to the inadequate blood supply to the nasopalatine region from the early embryonic stages possibly resulting from the discontinuity of the greater palatine artery.

An external reference to identify the internal auditory canal in middle fossa surgery.

Traditional middle fossa landmarks, such as the facial hiatus and arcuate eminence, are often unreliable. This study was performed to establish an external reference from which to identify precisely the surgical anatomy of the middle fossa. The head of the malleus was identified from the middle fossa in the temporal bones of 20 adults. The lateral cortex of the temporal squamosa at the zygomatic root was used as the external plane of reference. The head of the malleus was consistently located 18 mm medial to the outer cortex on a line perpendicular to the reference plane. Medial extension of this line through the malleus head bisected the internal auditory canal. We recommend this method to precisely locate the malleus head as the first landmark in the middle fossa. Other structures, such as the geniculate ganglion, internal auditory canal, and superior semicircular canal can then be safely identified. We also present our results using this technique in six consecutive patients undergoing middle fossa surgery during the past 12 months.

Dynamic force measurement in implantation of total endoprostheses of the hip joint

The forces within the femoral shaft have been studied in preparation for the total hip replacement. The experimental device consisted of a personal computer connected with a digital enhanced measurement system which converted the data, that was received from the strain gauges, mounted on the femur. The bitochanter hip replacement designed by Ecke was used as an example of a press fit endoprosthesis which is anchored cementless. It was implanted in femora of cadavers. The results showed an extension of the femur at first within the intertrochanteric region, and as the rasp was further implanted, it showed at the distal end of the rasp a medial extension and a lateral traction with a delay of 3 ms, proving that it was a result of a medullary extension. The maximum forces applied with the metal hammer were 3500 N. Fractures and fissures were provoked and the result showed that they were mostly due to a misplacement of the rasp.

Extraordinary new subterranean isopods (Peracarida: Crustacea) from the Kimberley Region, Western Australia

A new genus and two new species of fresh water isopods from ground waters of the Kimberley region of West Australia are described. This new genus cannot be immediately assigned to an isopod suborder or family because its unique combination of characters encompass many plesiomorphies, as well as synapomorphies with the 'Flabellifera' sensu lata. These features include free pleonites that are subequal except for an enlarged fifth pleonite, broad natatory pleopods, genital pores on medial extensions of the coxae, five pairs of oostegites, true coxal plates, an antennal protopod of three articles, and a rudimentary second flagellum on the antennula. One of the new species, well represented in one sample, is iteroparous and breeds continuously during the winter months. Because the type localities are from limestone fossil reefs not exposed to the marine environment since the Devonian period, these isopods may be remnants of an ancient freshwater stock. Name changes of some setal types are proposed.

Fracture of Temporal Bone With Exsanguination: Pathology and Mechanism

Eight cases of basal skull fracture with transverse fracture of the petrous temporal bone with medial extension to the internal carotid artery and lateral extension of the structures of the middle ear are described. Injuries in all cases were due to major blunt impact to the head usually occurring in a motor vehicle accident. General autopsy revealed major blood loss without any obvious external or internal site of hemorrhage suggesting that exsanguination was a complication of the head injury. The internal carotid arteries at the most medial extension of the fractures were lacerated or transected in all cases. In selected cases, the cervical internal carotid arteries were perfused and perfusate escaped rapidly from the ear(s) with the majority of fluid bypassing the cerebral venous system. Magnetic resonance image reconstruction of sequential sections of the fractured base of the skull confirmed the laceration of the internal carotid arteries and disruption of the middle ear. Based on this evidence, we propose that some displaced fractures of the base of the skull produce carotid-middle ear continuities which act as arterial shunts, resulting in rapid fatal exsanguination through the ear.

Central (third) fat pad of the upper eyelid

A clinical study on the surgical anatomy of the upper-eyelid fat pads was performed on 55 consecutive patients who underwent a blepharoplasty. It was confirmed that the periorbital fat is encapsulated in compartments and that the number of fat pads varies. In 56% of the cases there were two fat pads and in the 44% three fat pads in the upper eyelid. The third fat pad is anatomically and histologically an accessory medial extension of the lateral fat pad. However, for the sake of clarity, the term central fat pad of the upper eyelid is proposed as a denominator of this structure. The purpose of this article is to make the less experienced surgeons aware of variations in the configuration of the periorbital fat and to remind them that after two fat pads are removed from the upper eyelid there might still be a third.

Immunohistochemical study of the telencephalon of the spiny dogfish, Squalus acanthias

The paucity of experimental data and the differences in telencephalic organization between sharks and other jawed vertebrates have complicated telencephalic comparisons. The distribution of neuropeptides has been extremely useful in recognizing and comparing major subdivisions of the telencephalon among vertebrates. Immunohistochemical techniques were therefore used to study the distribution of substance P (SP), leucin-enkephalin (LENK), and serotonin (5HT), as well as tyrosine hydroxylase (TH), an indicator of catecholamines, in the telencephalon of the spiny dogfish. The distribution of SP and LENK provides a clear distinction between pallial and subpallial portions of the telencephalon. Two regions of the ventrolateral telencephalon, area superficialis basalis and area periventricularis ventrolateralis, exhibit histochemical similarities to the pallidal and striatal subdivisions, respectively, of the basal ganglia in amniotes. Lower densities of LENK+ and SP+ perikarya and fibers occur in the medial pallium and the pars centralis of the dorsal pallium. Similar histochemical traits characterize the sensory thalamorecipient telencephalic structures in amniotes. The lateral pallium in dogfishes is distinguished by the presence of large numbers of TH+ neurons with radially oriented processes. The presence of these distinctive cells also in the medial wall of the rostral telencephalon suggests that the lateral pallium has a medial extension that is situated ventral to the medial pallium. Neurons containing TH were widely distributed in the telencephalon of spiny dogfish and were particularly abundant in the dorsal pallium, olfactory pallium, and area superficialis basalis. It is currently unclear whether these TH+ telencephalic neurons are, in fact, catecholaminergic or merely contain a TH-like substance unrelated to catecholamine synthesis.

Endosymbiosis in the lucinid clams Lucinoma aequizonata, Lucinoma annulata and Lucina floridana: a reexamination of the functional morphology of the gills as bacteria-bearing organs

A three-dimensional representation of the structure of the endosymbiont-containing gills of Lucinoma aequizonata, L. annulata and Lucina floridana was constructed using light and electron microscopy of fresh and plastic-embedded thin-sectioned samples. The gills of these lucinids are identical in overall structure, each being composed of three structurally and functionally distinct regions here called the ctenidial filament zone (CFZ), the transition zone (TZ), and the bacteriocyte zone (BZ). Rather than a simple medial extension of the filament tissue, the bacteriocyte tissue is organized as an array of cylindrical tubes, the walls of which are composed primarily of bacteriocyte cells covered by a thin microvillar epithelium. The physical relationship between the symbionts, the host tissues and the external environment are examined, and structural constraints on the potential functions of bacteria in this host-symbiont system are discussed.

Cosmetic and reconstructive breast surgery in blacks.

Black women have not embraced cosmetic and reconstructive surgery of the breast with the same enthusiasm as their Caucasian counterparts because of fear of hypertrophic scars. The authors offer suggestions on how to minimize the scarring associated with breast surgery in black women. They feel that intraareolar incisions should be used whenever circumareolar incisions are indicated in augmentation mammaplasty, because the areola, being a favored area, is less likely to produce hypertrophic scars. The Marchac technique of reduction mammaplasty is recommended because it produces a short horizontal scar of 5 to 8 cm confined to the breast without medial and lateral extension, which may hypertrophy in black women. In the reduction of large breasts, secondary excision of dogears 6 or more weeks after mammaplasty reduces the medial and lateral extents of the scar. The use of liposuction as an adjunct to reduction mammaplasty may also accomplish the same thing. Amputation and free nipple-areola grafting should be used with caution in black patients because of the tendency of the grafted areola to hypopigment. In postmastectomy reconstruction, the authors suggest that the techniques described by Ryan and Radovan should be considered first before the techniques of reconstruction utilizing myocutaneous flaps. In these procedures, no new scars which may hypertrophy are created away from the site of reconstruction. Staples should not be used in skin closure in blacks because they cause cross-hatching of the wound even when removed early.

The mossy fiber projection of the nucleus reticularis tegmenti pontis to the flocculus and adjacent ventral paraflocculus in the cat

The pontine projection of the flocculus and adjacent ventral paraflocculus was investigated with antegrade and retrograde axonal tracer techniques. Injections of horseradish peroxidase into the floccular complex revealed subsets of labeled neurons in the nucleus reticularis tegmenti pontis, the nucleus raphe pontis and the medial lemniscus. Following injections of tritiated leucine in these subsets, the topographical distribution of labeled mossy fibers in the floccular complex was studied. Cells clustered in the central part of the nucleus reticularis tegmenti pontis project to the rostral flocculus and the rostral part of the caudal flocculus. The terminal field of cells in the nucleus raphe pontis and of cells associated with the lateral aspect of the medial lemniscus covered the same area. The number of mossy fiber terminals arising from these cells is small and concentrated in a medial position. The medial extension of the ventral paraflocculus and its most caudal sublobule do receive a very dense mossy fiber projection from cells associated with the medial edge of the medial lemniscus next to the rostral nucleus reticularis tegmenti pontis and beyond. Concomitantly, a collateral projection terminates in a restricted part of the uvula. Labeled mossy fiber terminals were never observed in the nodulus. The nucleus reticularis tegmenti pontis does not project to any part of the lower brain stem. The connections described in this paper are discussed in relation to the possible role of the nucleus reticularis tegmenti pontis as a relay nucleus in brain stem pathways transmitting visual information. It is concluded that in the cat this nucleus is an exclusively pre-cerebellar relay, not involved as a final link in the non-cerebellar pathway transmitting visual information to the vestibular nuclei.