Treatment, prevention and public health management of impetigo, scabies, crusted scabies and fungal skin infections in endemic populations: a systematic review

We conducted a systematic review of the treatment, prevention and public health control of skin infections including impetigo, scabies, crusted scabies and tinea in resource‐limited settings where skin infections are endemic. The aim is to inform strategies, guidelines and research to improve skin health in populations that are inequitably affected by infections of the skin and the downstream consequences of these. The systematic review is reported according to the PRISMA statement. From 1759 titles identified, 81 full text studies were reviewed and key findings outlined for impetigo, scabies, crusted scabies and tinea. Improvements in primary care and public health management of skin infections will have broad and lasting impacts on overall quality of life including reductions in morbidity and mortality from sepsis, skeletal infections, kidney and heart disease.

The laminar distribution of macaque tectobulbar and tectospinal neurons

The superior colliculus exerts its most direct influence over orienting movements, and saccades in particular, via its descending projections to the brain stem and spinal cord. However, while there is detailed physiological data concerning the generation of saccade-related activity in the primate superior colliculus, there is relatively little data on the detailed connectivity of this structure in primates. Consequently, retrograde transport techniques were utilized to determine the locations of the cells of origin of these descending pathways in macaque monkeys. Tectal cells that projected to the ipsilateral pontine reticular formation were mainly found in the deep gray layer and occasionally in the intermediate gray layer. Tectal cells that projected to the contralateral pontine reticular formation were predominantly located in the intermediate gray layer. The contralaterally projecting population could be subdivided into two groups. The cells in upper sublamina of the intermediate gray layer project primarily to the saccade-related regions of the paramedian reticular formation. Cells in the lower sublamina project primarily to more lateral regions of the pontine reticular formation and to the spinal cord. We conclude that the primate colliculus is provided with at least three descending output channels, which are likely to differ in their connections and functions. Specifically, it seems likely that the lower portion of the intermediate gray layer may be specialized to subserve combined head and eye orienting movements, while the upper sublamina subserves saccades.

A direct projection from superior colliculus to substantia nigra pars compacta in the cat

Dopaminergic neurons exhibit a short-latency, phasic response to unexpected, biologically salient stimuli. The midbrain superior colliculus also is sensitive to such stimuli, exhibits sensory responses with latencies reliably less than those of dopaminergic neurons, and, in rat, has been shown to send direct projections to regions of the substantia nigra and ventral tegmental area containing dopaminergic neurons (e.g. pars compacta). Recent electrophysiological and electrochemical evidence also suggests that tectonigral connections may be critical for relaying short-latency (<100 ms) visual information to midbrain dopaminergic neurons. By investigating the tectonigral projection in the cat, the present study sought to establish whether this pathway is a specialization of the rodent, or whether it may be a more general feature of mammalian neuroanatomy. Anterogradely and retrogradely transported anatomical tracers were injected into the superior colliculus and substantia nigra pars compacta, respectively, of adult cats. In the anterograde experiments, abundant fibers and terminals labeled with either biotinylated dextran amine or Phaseolus vulgaris leucoagglutinin were seen in close association with tyrosine hydroxylase-positive (dopaminergic) somata and processes in substantia nigra pars compacta and the ventral tegmental area. In the retrograde experiments, injections of biotinylated dextran amine into substantia nigra produced significant retrograde labeling of tectonigral neurons of origin in the intermediate and deep layers of the ipsilateral superior colliculus. Approximately half of these biotinylated dextran amine-labeled neurons were, in each case, shown to be immunopositive for the calcium binding proteins, parvalbumin or calbindin. Significantly, virtually no retrogradely labeled neurons were found either in the superficial layers of the superior colliculus or among the large tecto-reticulospinal output neurons. Taken in conjunction with recent data in the rat, the results of this study suggest that the tectonigral projection may be a common feature of mammalian midbrain architecture. As such, it may represent an additional route by which short-latency sensory information can influence basal ganglia function.

Agmatine Crosses the Blood-Brain Barrier

The question of whether agmatine crosses the blood-brain barrier has not been directly addressed, even though peripheral injection of this compound has produced behavioral responses in drug withdrawal, antidepressant, and anti-anxiety paradigms. Two models were used in this investigation. In the first, mice were injected intraperitoneally (i.p.) with agmatine (10, 50, or 300 mg/kg body weight) or arginine (600 mg/kg). After 1 or 3 hours, the animals were killed under gas anesthesia by perfusing their brains with ice-cold saline, and whole-brain agmatine was measured by HPLC. In parallel studies, a rhesus monkey was injected under gas anesthesia either intravenously (i.v.) with agmatine (30 mg/kg) or arginine (150 mg/kg), or intracerebroventricularly (i.c.v.) with agmatine (0.3 mg/kg i.c.v.). At varying times thereafter, cisterna magna cerebrospinal fluid (CSF) and blood plasma were collected and analyzed for agmatine levels. A rise in mouse brain agmatine was apparent after doses of 50 and 300 mg/kg i.p. Monkey CSF agmatine peaked in parallel with plasma agmatine 15 minutes following intravenous (i.v.) agmatine injection and at one sixth the level of the plasma peak. Monkey CSF agmatine peaked 43 minutes after i.v. arginine injection. The ventricular injection of agmatine resulted in a threefold sustained rise in blood plasma agmatine for at least 24 hours after injection. Therefore, agmatine and its precursor, arginine, cross the blood-brain barrier. CSF agmatine may be newly synthesized from peripherally injected arginine.

[Treatment of spinal fracture in ankylosing spondylitis]

Clinical guidelines for the treatment of vertebral fractures associated with ankylosing spondylitis are derived from case reports and a review of literature. The coincidence of paravertebral calcifications and fracture formations leads to problems in the establishment of a proper initial diagnosis. Therefore computed tomography and magnetic resonance imaging have to be employed to define the extent of fracture and the presence of spinal lesions. As a rule vertebral fractures based upon spondylitic alterations are extremely unstable and tend to secondary dislocation with a high risk of spinal cord injuries. Operative osteosynthesis is the method of choice in the fracture treatment. A successful stabilization requires an extended spondylodesis comprising at least five vertebral segments by a dorsal or a combined ventral instrumentation.

The feedback circuit connecting the superior colliculus and central mesencephalic reticular formation: a direct morphological demonstration

The central mesencephalic reticular formation (cMRF) has been distinguished from the surrounding reticular formation due to its involvement in the control of saccades. A role in saccade function has been proposed for this region based on electrical-stimulation experiments, its neuronal activity, and its pattern of connections. The present study was undertaken in an attempt to further characterize the location of the central mesencephalic reticular formation by anatomical methods and to examine its connections with the superior colliculus at the neuronal level. Biotinylated dextran amine (BDA) was injected into the superior colliculus of two cynomolgus monkeys (Macaca fascicularis). This resulted in the retrograde labeling of a large number of neurons in a restricted area of the mesencephalic reticular formation. They were distributed bilaterally, with an ipsilateral predominance, forming a cellular band in the ventral half of the midbrain reticular formation that was 2.7 mm in its rostrocaudal extent. Its rostral pole lay dorsolateral to the red nucleus and ventrolateral to, but not immediately adjacent to, the interstitial nucleus of Cajal. The cell band was widest caudally, where it occupied an area of approximately 2.7 mm wide and 2 mm in depth. Labeled neurons displayed a wide variety of multipolar somatic shapes and sizes, with long, slightly tapering, sparsely branched dendrites. Tectal terminal arbors were also labeled within the mesencephalic reticular formation. They were concentrated bilaterally, with an ipsilateral predominance, in the same areas that contained retrogradely labeled neurons. Numerous, primarily en passant labeled boutons of various sizes and shapes were seen in close association with both labeled and unlabeled neurons. They formed axosomatic and, more commonly, axodendritic relationships with labeled neurons. The extensive relationship of labeled terminals and labeled cells suggests the existence of a strong interconnection between the deeper layers of the colliculus and the central mesencephalic reticular formation neurons projecting back to the tectum. The bidirectional neural circuit directly demonstrated in this study presumably provides an anatomical substrate for feedback modification of gaze signals generated in the colliculus. However, the presence of tectal terminals around unlabeled reticular neurons suggests that the collicular signal may also be fed forward to the downstream targets of the central mesencephalic reticular formation.

The distribution of primary afferent terminals from the eyelids of macaque monkeys

Trigeminal sensory afferents from the eyelids convey two types of information that are important for the blink reflex. Movement of the lashes activates low-threshold mechanoreceptors which evoke protective blinks. Information about eyelid position is also transmitted centrally and is used to adapt the metrics of the blink reflex to changing conditions over time. This study employed transganglionic transport of horseradish peroxidase conjugated to choleratoxin-B subunit or wheat-germ agglutinin to investigate trigeminal afferents supplying the eyelids of macaque monkeys. Ganglion cells labeled from upper- and lower-lid injections were located in the ophthalmic and maxillary portions of the trigeminal ganglion, respectively. In both cases, labeled terminals were observed ipsilateral to the injected eyelid in the principal and spinal trigeminal nuclei. However, only a few labeled terminals were present in the principal nucleus, and very sparse terminal labeling was confined to a few locations along the ventral border of the pars oralis and interpolaris of the spinal trigeminal nucleus. The main concentration of label was found in the pars caudalis at and immediately below the spinomedullary junction. The terminal field from the upper eyelid was located ventrally in the pars caudalis, and that from the lower eyelid was located more dorsally. In both cases, the labeled terminal field was densest within lamina II of the spinal trigeminal nucleus. The heavy concentration of eyelid central terminals at the spinomedullary junction is surprising in light of physiological studies indicating representation of all parts of the face throughout the trigeminal nucleus. The distribution of eyelid afferent terminals in the macaque is caudal to the main concentration of corneal afferent terminals at the pars interpolaris/caudalis border. This may be a basis for differences seen in blinks produced by corneal as opposed to supraorbital stimulation. The presence of a single major site of eyelid primary afferent terminals suggests that sensory input for both eyelid proprioception and blink-reflex activation passes through this segment of the spinal trigeminal nucleus. These results provide a basis for investigation of the central connections of pars caudalis neurons in order to better establish the pathways producing trigeminally evoked blinks and blink adaptation.

Comparison of the distribution and somatodendritic morphology of tectotectal neurons in the cat and monkey

The presence of a commissure connecting the two superior colliculi suggests they do not act independently, but the function of the tectotectal connection has never been firmly identified. To develop a better understanding of this commissural system, the present study determined the distribution and morphology of tectotectal neurons in the cat and macaque monkey, two animals with well-studied, but different orienting strategies. First, we compared the distribution of tectotectal cells retrogradely labeled following WGA-HRP injections into the contralateral superior colliculus. In monkeys, labeled tectotectal cells were found in all layers, but were concentrated in the intermediate gray layer (75%), particularly dorsally, and the adjacent optic layer (12%). Tectotectal cells were distributed throughout nearly the entire rostrocaudal extent of the colliculus. In cats, tectotectal cells were found in all the layers beneath the superficial gray, but the intermediate gray layer contained the greatest concentration (56%). Labeled cells were almost exclusively located in the rostral half of the cat superior colliculus, in contrast to the monkey distribution. In the context of the representation of visuomotor space in the colliculus, the distribution of monkey and cat tectotectal cells suggests a correspondence with oculomotor range. So these neurons may be involved in directing orienting movements performed within the oculomotor range. The somatodendritic morphology of tectotectal cells in these two species was revealed by homogeneous retrograde labeling from injections of biocytin or biotinylated dextran amine into the contralateral colliculus. The cell classes contributing to this pathway are fairly consistent across the two species. A variety of neuronal morphologies were observed, so there is no single tectotectal cell type. Instead, cell types similar to those found in each layer, excepting the largest neurons, were present among tectotectal cells. This suggests that a sample of each layer's output is sent to the contralateral colliculus.

Reciprocal connections between the zona incerta and the pretectum and superior colliculus of the cat

The goal of the present experiments was to examine the relationships of the zona incerta with two structures associated with visuomotor behavior, the superior colliculus and pretectum. The experiments were carried out in the cat, a species commonly used in studies of visuomotor integration, and utilized wheat germ agglutinin horseradish peroxidase and biocytin as retrograde and anterograde neuronal tracers. Retrograde axonal transport demonstrated that most cells in the ventral subdivision of the zona incerta project to the superior colliculus. Anterograde tracers demonstrated that the incertotectal terminal field is most dense in the intermediate gray layer, which is the primary source of the descending pathway from the superior colliculus to brainstem gaze centers. Further experiments showed that scattered cells within the intermediate gray layer give rise to a reciprocal pathway that terminates in both the dorsal and ventral subdivisions of the zona incerta. The distribution of both labeled incertotectal cells and tectoincertal terminals extends dorsolateral to the zona incerta proper, between the reticular thalamic nucleus and the external medullary lamina. Electron microscopic examination of labeled tectoincertal terminals demonstrated that they contain mainly spherical vesicles and have slightly asymmetric to symmetric synaptic densities. Labeled terminals were observed contacting labeled cells in the zona incerta, suggesting that the reciprocal pathway may be monosynaptic. The zona incerta is also reciprocally interconnected with the pretectum. The anterior pretectal nucleus provides a dense projection to the ventral part of the zona incerta and receives a sparse reciprocal projection. The posterior pretectal nucleus and nucleus of the optic tract may also project to the zona incerta. The pretectoincertal fibers form terminals that contain primarily spherical vesicles and make distinctly asymmetric synaptic contacts. In summary, these results indicate that the deep layers of the superior colliculus, which are important for controlling saccades, are the target of a projection from the ventral subdivision of the zona incerta. Like the substantia nigra, the zona incerta may play a permissive role in the tectal initiation of saccadic eye movements. The incertotectal terminal field in the cat is less dense than that observed previously in the rat, suggesting species differences in the development of this pathway. An additional finding of this study is that one of the main sources of input to these incertotectal cells is the anterior pretectal nucleus. This pretectal incertal tectal pathway is likely to play a role in the guidance of tectally initiated saccades by somatosensory stimuli.

Aberrant reinnervation of facial musculature in a subhuman primate: a correlative analysis of eyelid kinematics, muscle synkinesis, and motoneuron localization

A macaque monkey with a preexisting facial nerve injury showed a synkinesis of perioral muscles with blinking and thus provided a serendipitous model for a multiphasic analysis of this common neurologic syndrome. The amplitude of the paretic eyelid in spontaneous and air-puff-induced blinks was about one-third that of the normal eyelid. Despite the blink hypometria, induced blink durations remained matched for the two lids. EMG confirmed co-contraction of the zygomaticus and orbicularis oculi muscles on the affected side during blinking, with silence of the zygomaticus on the normal side. Neuroanatomic investigation showed that, on the affected side, some zygomaticus motoneurons were in the somatotopically correct nuclear subdivisions but that the majority were in the dorsal subdivision, which normally innervates the orbicularis oculi. This study supports the contention that some orbicularis oculi motoneurons are incorrectly rerouted to supply the perioral musculature following recovery from a peripheral seventh-nerve injury. This same pattern of relative weakness in eyelid muscles and the stereotyped co-contraction of lid and perioral muscles with blinking occurs in humans, suggesting that aberrant reinnervation may be the mechanism for this clinical phenomenon.

NADPH-diaphorase reactivity in ciliary ganglion neurons: a comparison of distributions in the pigeon, cat, and monkey

Ciliary ganglia from the pigeon, cat, and monkey were investigated for the presence of NADPH-diaphorase reactivity by use of a standard histochemical method. In the pigeon, where the ganglion is known to control lens and pupil function, and the choroidal vasculature, about one-third of the ganglion cells were densely stained and most other somata were lightly stained. In some cases, preganglionic terminals with a cap-like morphology were also darkly stained. The pattern of NADPH-diaphorase staining in mammals was very different from that seen in pigeons. In both mammalian species, where the ganglion is known to control lens and pupil function, a small number (less than 2%) of the ganglion cells were shown to be densely NADPH-diaphorase positive, revealing their neuronal processes. The presence of NADPH-diaphorase positive cells in pigeon, cat, and monkey ciliary ganglia suggests that nitric oxide may be used for intercellular communication in this ganglion, or in light of the known importance of nitric oxide in vascular control, some of these positive neurons may participate in the control of choroidal vasodilation.

Ultrastructure of the macaque ciliary ganglion

The primate ciliary ganglion is an obligatory relay in the pathways that control the lens and pupil for the near response and the light reflex, two functions which have been the target of increasing inquiry in behavioural physiology paradigms. This investigation provides a comprehensive description of the ultrastructure of the ciliary ganglion in the rhesus monkey (Macaca mulatta). The results indicate that the ciliary ganglion contains a heterogeneous population of neurons in terms of somatic size, cytoplasmic contents and somatodendritic distribution of terminals. Variations in the clear and dense-cored vesicle content of the synaptic profiles present in the ganglion suggest that the synaptic inputs are also heterogeneous and may mediate separate functions. Several characteristic ultrastructural features of the macaque ciliary ganglion are noteworthy. Despite the large size of the neuronal somata, most cells do not exhibit contacts directly onto the somatic membrane. However, the few somata that do receive direct input often display several axosomatic contacts. The vast majority of synaptic interactions occur in the perisomatic neuropil, where the postsynaptic elements consist of simple and complex somatic appendages, as well as dendrites with their appendages. There is little neuropil independent of these immediately perisomatic regions. In some cases, axonal terminals form the central element of complex glomeruli, in which they are presynaptic to numerous spine-like profiles. In other cases, axon terminals and their postsynaptic targets are found within shallow depressions in the somatic membrane or, occasionally, deeply embedded within the borders of the postganglionic neuron. The somata and all the non-myelinated neuronal elements are surrounded by interdigitating, electron-dense processes of satellite cells. These glial cells are sometimes found in shallow recesses, or deeply embedded within the borders of the neuronal somata. The complexity of the ultrastructure of the ciliary ganglion in the macaque suggests that this ganglion may not be a simple relay in the parasympathetic outflow to the eye, but may instead be the site of neuronal processing of the preganglionic input.

Organization of the extraocular and preganglionic motoneurons supplying the orbit in the lesser Galago

The retrograde tracer wheat germ agglutinin-conjugated horseradish peroxidase was used to establish the organization of the extraocular muscle motoneuron pools in a prosimian, Galago senegalensis, for comparison with the organization in monkeys and non-primates. Medical rectus motoneurons were distributed in three subgroups in the ipsilateral oculomotor nucleus, a pattern similar to that of the monkey. Furthermore, the other component of the near response system, the preganglionic parasympathetic motoneurons, were confined within the Edinger-Westphal nucleus, as in the monkey. In contrast, the distribution of the levator palpebrae and superior rectus motoneurons was similar to that of the cat. Specifically, the majority of levator palpebrae motoneurons were located contralaterally, in the caudal central subdivision of the oculomotor nucleus, and the superior rectus motoneurons had a dorsocaudal location in the contralateral oculomotor nucleus. The distributions of motoneurons supplying the superior oblique and lateral rectus muscles were similar to those of other mammals. Unlike previously studied species, the galago was found to have two accessory muscles, that lie beneath the medial and lateral rectus muscles. Motoneurons supplying the accessory rectus muscles were found ventrolateral to the main abducens nucleus, in a position similar to that occupied by the cat accessory abducens nucleus; although others may be present in the main nuclei. Taken together, these results suggest that the organization of extraocular and preganglionic motoneurons in the galago exhibits both monkey and non-primate features. These observations are consistent with the notion that the galago is a primate species whose oculomotor organization is more similar to the general mammalian scheme.

Interconnections between the primate cerebellum and midbrain near-response regions

The goal of this study was to determine the pattern of the connections between the midbrain and cerebellum that may play a role in the modulation of the near-response in the macaque. Injection of the retrograde tracer wheat germ agglutinin conjugated horseradish peroxidase (WGA-HRP) into the physiologically identified midbrain near-response region, which includes the supraoculomotor area, labelled cells throughout the deep cerebellar nuclei. However, labelled cells were particularly concentrated in the ventrolateral corner of the contralateral posterior interposed nucleus and in the contralateral and, to a lesser extent, the ipsilateral fastigial nuclei. Subsequently, injections of WGA-HRP were used to define the midbrain terminations of the deep cerebellar nuclei. Fastigial nucleus injections labelled terminals in a band along the border between the oculomotor nucleus and the supraoculomotor area that included the Edinger-Westphal nucleus. Injections of the posterior interposed nucleus labelled terminals in the portion of the supraoculomotor area dorsal to the fastigial projection and did not involve the Edinger-Westphal nucleus. In both cases, the terminal label was primarily found contralaterally. In contrast, retrogradely labelled cells were primarily found ipsilaterally within the supraoculomotor area following cerebellar injections. Retrogradely labelled cells projecting to the deep nuclei were also found bilaterally in the anteromedian nucleus, along with sparse terminal label. Taken as a whole, these results demonstrate the presence of a highly specific pattern of labelling in the supraoculomotor area, which may indicate that the posterior interposed nucleus and the fastigial nucleus play different roles in the control of the near-response. Alternatively, these projections may subserve other functions, such as modulating the pupillary light reflex. The fact that the projection from the deep nuclei is primarily contralateral, while the supraoculomotor projection to the deep nuclei is primarily ipsilateral, suggests that this may not be a simple feedback system, but may instead be involved in balancing the gains in the two eyes. In sum, physiological experiments have indicated the presence of near-response neurons in the midbrain supraoculomotor area and have indicated that the cerebellum may play a role in modulating the components of the near-response, as well as activity in the intrinsic eye muscles. The present experiments suggest a pattern of connections that might subserve this cerebellar modulation.

Neuronal connections between the cerebellar nuclei and hypothalamus in Macaca fascicularis: cerebello-visceral circuits

The purpose of this study was to identify the basic pattern of interconnections between the cerebellar nuclei and hypothalamus in Macaca fascicularis. The distribution of retrogradely labeled cells and anterogradely filled cerebellofugal axons in the hypothalamus of M. fascicularis was investigated after pressure injections of a horseradish peroxidase mixture (HRP + WGA-HRP) in the cerebellar nuclei. Following injections in the lateral, anterior, and posterior interposed cerebellar nuclei retrogradely labeled cells were present in the following areas (greatest to least concentration): lateral and dorsal hypothalamic areas, dorsomedial nucleus, griseum periventriculare hypothalami, supramammillary and tuberomammillary nuclei, posterior hypothalamic area, ventromedial nucleus and periventricular hypothalamus, around the medial mammillary nucleus, lateral mammillary nucleus, and infundibular nucleus. Cell labeling was bilateral with an ipsilateral preponderance. In these same experiments anterogradely labeled cerebellar efferent fibers terminated in the contralateral posterior, dorsal and lateral hypothalamic areas, and the dorsomedial nucleus. In these regions retrogradely labeled hypothalamic cells were occasionally found in areas that also contained anterogradely filled cerebellar axons. This suggests a partial reciprocity in this system. In addition, sparse numbers of labeled cerebellar fibers recross in the hypothalamus to distribute to homologous areas ipsilateral to the injection site. Subsequent to an injection in the medial cerebellar nucleus (NM), cell labeling was present in more rostral hypothalamic levels including the lateral and dorsal hypothalamic areas, the dorsomedial nucleus, around or in fascicles of the column of the fornix, and in the periventricular hypothalamic area. Although no fastigiohypothalamic fibers were seen in this study, on the basis of information available from the literature it is likely that such a connection exists in primates. In summary, hypothalamic projections to NM originated mainly from rostral to midhypothalamic levels, whereas those projections to the lateral three cerebellar nuclei came from mid and more caudal levels. The existence of direct hypothalamic projections to cerebellar nuclei in M. fascicularis and of cerebellofugal projection to some hypothalamic centers indicates that circuitry is present through which the cerebellum may influence visceral functions. Furthermore, the fact that projections to NM versus the other cerebellar nuclei originate from somewhat different regions of the hypothalamus would suggest that the visceral functions modulated by each pathway is not the same.

Synaptic organization of tectal-facial pathways in cat. II. Synaptic potentials following midbrain tegmentum stimulation

1. The organization of the synaptic pathways underlying midbrain tegmentum influence over the facial musculature was studied with the use of an acute electrophysiological approach in the cat. Under pentobarbital sodium anesthesia, synaptic potentials were recorded intracellularly in antidromically identified facial motoneurons following electrical stimulation of the paralemniscal zone. The cells of origin and the pathways responsible for the potentials evoked from the paralemniscal zone were defined with the use of retrograde transport of horseradish peroxidase (HRP). The putative role of the paralemniscal zone with regard to the production of disynaptic, tectally evoked potentials in facial motoneurons was investigated both by inactivating this nucleus with injections of lidocaine and by making acute brain stem lesions to sever the paralemniscal-facial and other afferent pathways. 2. Following paralemniscal stimulation, monosynaptic, excitatory postsynaptic potentials (EPSPs) with latencies ranging from 0.6 to 0.9 ms, steep rising phases, and amplitudes in excess of 4.0 mV were recorded in motoneurons of the temporal and auriculoposterior subdivisions, which supply the pinna muscles. Smaller amplitude EPSPs (less than 1.0 mV) with monosynaptic latencies were observed in the zygomatic subdivision. Polysynaptic EPSPs with latencies ranging from 1.0 to 1.8 ms were also observed in all three of these subdivisions. However, only long-latency EPSPs, arriving at 2.0 ms or later, were present in ventral subdivision motoneurons. 3. Inhibitory postsynaptic potentials (IPSPs) were also frequently recorded in facial motoneurons after paralemniscal stimulation. Monosynaptic IPSPs with latencies ranging from 0.8 to 1.2 ms and amplitudes in excess of 4.0 mV were recorded in facial motoneurons of the temporozygomatic and auriculoposterior subdivisions, as were polysynaptic IPSPs with latencies ranging from 1.2 to 1.8 ms. IPSPs were sometimes observed in combination with a smaller, shorter latency EPSPs. Only long-latency IPSPs of greater than 2.0 ms were recorded in ventral subdivision motoneurons. In all cases, both the EPSPs and the IPSPs were graded in character and could be augmented by multiple stimuli. 4. The contralateral paralemniscal zone and the supraoculomotor area, bilaterally, represented the two most prominent afferent sources labeled after HRP injection of the facial nucleus. The superior colliculus and numerous reticular formation regions were also identified as facial nucleus afferents by the presence of retrogradely labeled cells. The retrogradely labeled cells in the paralemniscal zone exhibited heterogeneous soma size. HRP-labeled axons of the paralemniscal-facial pathway were observed to cross the midline by traveling ventral to the brachium conjunctivum in the caudal mesencephalon.(ABSTRACT TRUNCATED AT 400 WORDS)

Cerebellotectal pathways in the macaque: implications for collicular generation of saccades

The cerebellum is thought to modulate saccadic activity in the primate in order to maintain targeting accuracy, and the cerebellotectal pathway has been posited to play a role in this modulation. However, anatomical descriptions of this pathway in primates are sketchy and conflicting. To determine whether the organization of the cerebellotectal projection in primates is similar to that found in other species, neuroanatomical tracer transport techniques were utilized in two species of macaque monkey to label cerebellotectal somata and fiber terminations. Two pathways were found. One, the fastigiotectal pathway, is derived from cells in the caudal fastigial nucleus and projects bilaterally to the rostral end of the intermediate gray layer. The other pathway is derived from cells in the posterior interposed nucleus and the adjacent posterior wing of the dentate nucleus, and it terminates contralaterally throughout the ventral half of the intermediate gray and the deep gray layers. Both of these pathways terminate within the layers of the superior colliculus containing premotor, saccade-related neurons, but the differences in the distribution of their terminals and cells of origin suggest that these two pathways have different functions. Furthermore, the pattern of connections of these two pathways indicates that they do not function as a traditional feedback circuit. We suggest that the cerebellotectal pathways may instead modulate collicular activity in a more complex manner. For example, it may provide signals necessary for corrective saccades or for maintaining spatial registry between the different sensory representations supplied to the superior colliculus and its presaccadic output, which is organized into a motor map.

Morphological substrate for eyelid movements: innervation and structure of primate levator palpebrae superioris and orbicularis oculi muscles

The levator palpebrae superioris and orbicularis oculi are antagonistic muscles that function during movements of the eyelid. The levator also functions in conjunction with superior and inferior rectus muscles in coordinated eye/lid movements. The present study examined the innervation and morphology of these muscles in Cynomolgous monkeys (Macaca fascicularis) in order to provide a better understanding of the anatomical substrate for lid movements. Motoneurons innervating the levator and orbicularis muscles were identified and localized by retrograde transport of WGA/HRP and HRP. Retrogradely labelled levator motoneurons were distributed bilaterally throughout the caudal central division of the oculomotor nucleus. A few labelled cells were also present within the contralateral superior rectus division, possibly because of the spread of tracer at the injection site. The possibility that individual motoneurons collateralize to innervate the levator muscle bilaterally was tested by using double retrograde labelling techniques. Doubly labelled levator motoneurons could not be detected by using a combination of tracers (HRP and Fast Blue). Motoneurons innervating the upper lid portion of the orbicularis oculi muscle were distributed within the dorsal subdivision of the ipsilateral facial motor nucleus, with a few neurons in the corresponding locus of the contralateral facial nucleus. Species differences in levator motoneuron distribution, particularly distinctions in lateral-eyed versus frontal-eyed mammals, are discussed in relation to the neural control of lid movements. The levator palpebrae superioris contains three of the same ultrastructurally defined types of singly innervated muscle fiber found in the global layer of other extraocular muscles and an additional, unique slow-twitch fiber type. Moreover, the multiply innervated fiber types so characteristic of the other extraocular muscles are conspicuously absent from levator muscles. Unlike the rectus and oblique extraocular muscles, the levator lacks a layered distribution of fiber types. The morphological profiles of levator muscle fiber types are such that they generally do not respect traditional fiber classification schemes, but are consistent with a role for the levator in sustained elevation of the lid. The orbicularis oculi muscle, by contrast, exhibited three distinct fiber types that resembled categories of skeletal muscle twitch fibers. One slow-twitch and two fast-twitch fiber types were noted. On the basis of oxidative enzyme profiles and mitochondrial content, the majority of orbicularis oculi fibers would be fatigue-prone, an assessment consistent with their rapid onset/offset of acti

Synaptic organization of the tectal-facial pathways in the cat. I. Synaptic potentials following collicular stimulation

1. The synaptic pathways underlying tectal influence over pinna movements were studied using an acute electrophysiological approach. Under pentobarbital anesthesia, postsynaptic potentials were recorded intracellularly in antidromically identified, cat facial motoneurons following electrical stimulation of the superior colliculus. How collicular topography is reflected in these synaptic potentials was examined using multiple stimulation sites. The pathways responsible for tectally evoked synaptic potentials were studied by making acute brain stem lesions and by intra-axonal horseradish peroxidase (HRP) staining. 2. Monosynaptic excitatory potentials (EPSPs) with latencies ranging from 0.7 to 1.1 ms and amplitudes that were always less than 1 mV were recorded in motoneurons following stimulation of the contralateral superior colliculus. Larger disynaptic EPSPs ranging in latency from 1.2 to 2.0 ms were recorded both in isolation and in association with monosynaptic EPSPs. In addition, disynaptic inhibitory synaptic potentials (IPSPs) with latencies ranging from 1.5 to 2.5 ms were observed, often in combination with monosynaptic EPSPs. Both disynaptic EPSPs and IPSPs were graded, augmented by multiple stimuli and found in all categories of motoneurons. 3. Stimulation of the ipsilateral superior colliculus produced nearly the same spectrum of potentials and latencies as did contralateral tectal stimulation. Occlusion between ipsi- and contralaterally evoked IPSPs suggests there might be a common element in the inhibitory disynaptic pathways. 4. More discrete populations of facial motoneurons were investigated. Specifically, motoneurons innervating the platysma and orbicularis oculi muscles, the intrinsic ear muscles, and muscles that move the vibrissae all displayed tectally elicited mono- and di-synaptic potentials. Collicular input was not restricted to motoneurons involved in orienting the pinnae. 5. The presence, polarity, and amplitude of the synaptic potentials evoked in individual facial motoneurons exhibited variations that were related to the site of stimulation in either the ipsi- or contralateral colliculus. These variations are compatible with the idea that the collicular input to facial motoneurons is topographically organized. 6. Acute lesions at the level of the superior olive indicated that the pathway producing the contralateral monosynaptic EPSPs runs, near the midline, ipsilateral to the target facial nucleus, whereas the contralateral disynaptic and the ipsilateral mono- and disynaptic pathways lie further lateral.(ABSTRACT TRUNCATED AT 400 WORDS)

Morphology and distribution of serotoninergic and oculomotor internuclear neurons in the cat midbrain

Serotoninergic fibers have been reported in both the abducens and facial nuclei of the cat. Furthermore, serotoninergic dorsal raphe and oculomotor internuclear neurons occupy similar locations in the periaqueductal gray overlying the oculomotor and trochlear motor nuclei. To resolve the issue of whether these two populations of neurons overlap, serotoninergic fibers were assayed in the abducens and facial nucleus; then the morphologies and distributions of identified serotoninergic neurons and oculomotor internuclear neurons were determined. Both the abducens and facial nuclei contained varicosities labelled with antibody to serotonin, but a much higher density of immunoreactive fibers was present in the latter, especially in its medial aspect. Distinct synaptic profiles labelled with antibodies to serotonin were observed in both nuclei. In both cases, terminal profiles contained numerous small, predominantly spheroidal, synaptic vesicles as well as a few, large, dense-core vesicles. These profiles made synaptic contacts onto dendritic and, in the facial nucleus, somatic profiles that occasionally displayed asymmetric, postsynaptic, membrane densifications. Following injection of horseradish peroxidase into either the abducens or facial nuclei, double-label immunohistochemical techniques demonstrated that the serotoninergic and oculomotor internuclear neurons form two distinct cell populations. The immunoreactive serotoninergic cells were distributed within the dorsal raphe nucleus, predominantly caudal to the retrogradely labelled oculomotor internuclear neurons. The latter were located in the oculomotor nucleus along its dorsal border and in the adjacent supraoculomotor area. Intracellular injection of horseradish peroxidase revealed that oculomotor internuclear neurons have multipolar somata with up to ten long, tapering dendrites that bifurcate approximately five times. Their dendritic fields were generally contained within the nucleus and adjacent supraoculomotor area. In contrast, putative serotoninergic neurons were often spindle-shaped and exhibited far fewer primary dendrites. Many of these long, narrow, sparsely branched dendrites crossed the midline and extended to the surface of the cerebral aqueduct. In the vicinity of the aqueduct they branched repeatedly to form a dendritic thicket. The axons of the intracellularly stained serotoninergic neurons emerged either from the somata or the end of a process with dendritic morphology, and in some cases they produced axon collaterals within the periaqueductal gray. Thus the oculomotor internuclear and serotoninergic populations differ in both distribution and morphology.(ABSTRACT TRUNCATED AT 400 WORDS)

The cerebellotectal pathway in the grey squirrel

In the well laminated superior colliculus of the grey squirrel the cells of origin of the crossed descending pathway to the brainstem gaze centers are contained within the inner sublamina of the intermediate grey layer. The technique of anterograde transport of horseradish peroxidase was used to determine whether the pathway from the cerebellum to the superior colliculus terminates in this region. The technique of retrograde transport of horseradish peroxidase was used to localize the source of this pathway within the cerebellum and to determine the morphology of the cerebellotectal neurons. The grey squirrel cerebellotectal pathway provides two terminal fields to the superior colliculus: a diffuse projection into the deep grey layer and a more concentrated, interrupted projection into the inner sublamina of the intermediate grey layer. The more concentrated projection overlies precisely the tectal sublamina that contains the cells of origin of the predorsal bundle. In contrast to animals with frontal eyes, the cerebellotectal pathway in the grey squirrel was found to project almost entirely contralaterally and the vast majority of the cells of origin for the pathway were distributed ventrally, in the caudal pole of the posterior interpositus nucleus and the adjacent region of the dentate. The labelled cells in both cerebellar nuclei were large and displayed similar morphologies.

The sources of the nigrotectal pathway

The nigrotectal pathway plays a role in the generation of saccade related responses by cells in the deep layers of the superior colliculus. By using a retrograde horseradish peroxidase technique that homogeneously fills neurons, the present experiments demonstrate that the source of the nigrotectal projection to the intermediate gray layer of the grey squirrel (Sciurus carolinensis) is a heterogeneous population of neurons whose somas and dendrites are concentrated in the rostral pole of pars reticulata. This region of pars reticulata receives projections from the posterior caudate, which in turn is a target of both the pulvinar and visual cortex. In addition, these experiments reveal the presence of a second, distinct set of neurons projecting to the midbrain tectum that are located in pars lateralis of the substantia nigra. These neurons can be distinguished from those in pars reticulata by their homogeneity and by their prominent basal dendrites. Furthermore, pars lateralis of the squirrel substantia nigra is, on cytoarchitectonic and immunocytochemical grounds, a distinct subdivision that does not receive projections from the posterior caudate. We conclude that both pars reticulata and lateralis are sources of the nigrotectal pathway. In addition, our results suggest, on connectional grounds, that the rostral pole of pars reticulata may be specialized to subserve the visual guidance of orienting movements.

Urea, meat meal or lupins as nitrogen supplements to barley and hay diets for yearling cattle at two levels of body condition

Weaner steers were fed to attain either fat score 1 or 2 by the time that they were 1 year of age. Animals at each fat score were then either slaughtered or fed ad libitum on a basal barley and hay diet containing 11% crude protein or similar diets supplemented by either urea, meat meal or sweet lupins to contain 13% crude protein in the dry matter. Those fed were slaughtered as they attained fat score 3. Compared with those starting at fat score 2, the yearlings at fat score 1 had the same daily feed intake and thus a 10% higher relative intake, grew 15% faster and required 11% less feed per kg liveweight gain. However, they required only 6% less feed per kg carcass weight gain, owing to their 1% lower dressing percentage. The diets supplemented with the three different sources of supplementary nitrogen gave similar improvements over the basal diet in intake, growth rate and efficiency, and there were no interactions between diet and fat score. It was concluded that both the National Research Council and Agricultural Research Council feeding standards underestimate the nitrogen concentration required in grain and hay diets to ensure maximum performance and efficiency by yearling cattle growing from 220 to 370 kg liveweight, and that supplements of either urea, meat meal or lupins providing an extra 2 percentage units of crude protein improve performance to a similar extent.

Nonintralaminar thalamostriatal projections in the gray squirrel (Sciurus carolinensis) and tree shrew (Tupaia glis)

In mammals, the corpus striatum receives prominent projections from the neocortex and from the intralaminar nuclei of the dorsal thalamus. The present study provides evidence based on anterograde degeneration and axonal transport that the corpus striatum also receives input from two nonintralaminar thalamic nuclei, the pulvinar and the medial geniculate body. Each of these nuclei projects to a separate region of the corpus striatum. Moreover, the same regions of the corpus striatum that receive projections from the pulvinar and medial geniculate body also receive projections from the cortical targets of these nuclei.

Relationships between the nigrotectal pathway and the cells of origin of the predorsal bundle

The goal of this study was to define the anatomical relationships between the terminal field of the nigrotectal pathway and the tectal neurons which project to contralateral brainstem gaze centers by way of the predorsal bundle. The distribution and morphology of the cells of origin for the predorsal bundle were determined by using a modification of the retrograde horseradish peroxidase technique which homogeneously filled their somas and dendrites. The terminal distribution of the nigrotectal tract was determined using both anterograde horseradish peroxidase and autoradiographic procedures. The results indicate that, in the grey squirrel (Sciurus carolinensis), the predorsal bundle cells are a heterogeneous population whose dendritic fields form a well-defined band confined to the inner half of stratum griseum intermediate. This inner sublamina also can be identified in Nissl and myelin stains. The same sublamina is the major target of the nigrotectal tract. The striking anatomical correspondence between the distribution of nigrotectal terminals and the cells projecting in the predorsal bundle supports a proposal, based on recent physiological investigations, that the nigrotectal tract plays an important role in the initiation of the saccade-related activity of the deep tectal cells (Chevalier et al., '81; Hikosaka and Wurtz, '83a-d).

Formulating disaster relief when needs are unknown

As in most cases of natural disasters, relief needs arising out of the Mount St. Helens volcanic eruptions in May 1980 were greatly overestimated. Technical, bureaucratic, and political considerations all contribute to the upward bias in such cases. The errors in early estimates of relief needs can be reduced by systematic means. But more important than obtaining good early estimates is maintaining an effective control over actual disaster relief expenditures. As it turns out, the more effective systems of control usually go hand in hand with poorer early estimates, creating a dilemma for the management for disaster relief.