Lateral Pontine Nuclei Research Articles

Localized metabolic responses to optokinetic stimulation in the brain stem nuclei and the cerebellum investigated with the [ 14C]2-deoxyglucose method in rats

The localized metabolic effects of monocular optokinetic stimulation to the cerebellar flocculus and brain stem nuclei were measured in pigmented rats. Quantitative [ 14C]2-deoxyglucose autoradiography was performed on alert rats stimulated with a drum either rotated horizontally in the temporonasal direction (optokinetic group) or kept stationary (control group). The superior colliculus in both groups showed a higher amount of activity on the contralateral side to the stimulated eye than on the ipsilateral side. The dorsal cap of the inferior olive, the nucleus of the optic tract, and the lateral pontine nucleus showed a higher amount of activity on the contralateral side only in the optokinetic group. The nucleus reticularis tegmenti pontis and the ventromedial aspect of the cerebellar paraflocculus showed no lateralized activity in either group. Local glucose utilization rates of both flocculi were significantly enhanced in the optokinetic group. Only in the optokinetic group did the ipsilateral flocculus show a higher local glucose utilization rate than the contralateral flocculus. The most enhanced activity was localized in the middle aspect of the rostrocaudal extent of the ipsilateral flocculus. The activity was greater in the granular layer than in the molecular layer or in the white matter. The pattern of activation in the granular layer was characterized by a patchy appearance in the frontal sections. Serial reconstruction of these sections showed metabolic blobs appearing with intervals of several hundred micrometers.

Autoradiographic localization of nicotinic acetylcholine receptors in the brain of the zebra finch (Poephila guttata).

We have localized nicotinic acetylcholine receptors in the zebra finch brain by using three 125I-labelled ligands: alpha bungarotoxin and two monoclonal antibodies to neuronal nicotinic receptors (MAb 35 of Tzardos et al., J. Biol. Chem., 250: 8635-8645, '81; and MAb 270 of Whiting and Lindstrom: J. Neurosci. 6: 3061-3069, '86). Unfixed brains from intact adult male and female zebra finches were prepared for in vitro autoradiography. Low-resolution film autoradiograms and high-resolution emulsion autoradiograms were prepared for each of the three ligands. The major brain structures that bind all three of the ligands are hippocampus; hyperstriatum dorsalis; hyperstriatum ventralis; nucleus lentiformis mesencephali; nucleus pretectalis, some layers of the optic tectum; nucleus mesencephalicus lateralis; pars dorsalis; locus ceruleus; and all cranial motor nuclei except nucleus nervi hypoglossi. The major structures labelled only by [125I]-alpha bungarotoxin binding included hyperstriatum accessorium and the nuclei: preopticus medialis, medialis hypothalami posterioris, semilunaris, olivarius inferior, and the periventricular organ. Of the song control nuclei, nucleus magnocellularis of the anterior neostriatum; hyperstriatum ventralis, pars caudalis; nucleus intercollicularis; and nucleus hypoglossus were labelled. The binding patterns of the two antibodies were similar to one another but not identical. Both labelled nucleus spiriformis lateralis and nucleus geniculatus lateralis, pars ventralis especially heavily and also labelled the nucleus habenula medialis; nucleus subpretectalis; nucleus isthmi, pars magnocellularis; nucleus reticularis gigantocellularis; nucleus reticularis lateralis; nucleus tractus solitarii; nucleus vestibularis dorsolateralis; nucleus vestibularis lateralis; nucleus descendens nervi trigemini; and the deep cerebellar nuclei. Lobus parolfactorius and nucleus vestibularis medialis were labelled by only MAb 270, whereas only MAb 35 labelled nucleus laminaris and the medial and lateral pontine nuclei. These data extend previous reports of cholinergic participation in the song system (Ryan and Arnold: J. Comp. Neurol. 202: 211-219, '81) to suggest that the zebra finch song system may contain several closely related nicotinic receptors. In several brain nuclei it appeared that certain anatomical portions of a nucleus or a certain class of neurons were specifically labelled. Furthermore, in certain cases, the labelling appeared to be clustered around Nissl-stained cell nuclei, thus suggesting that the receptors are concentrated on or in somata.

Neocortical connections in fetal cats

The major extrinsic projections to and from visual and auditory areas of cerebral cortex were examined in fetal cats between 46 and 60 days of gestation (E46–E60) using axonal transport of horseradish peroxidase either alone or in combination with tritiated proline. Projections to visual cortex from the dorsal lateral geniculate nucleus and lateral-posterior/pulvinar complex exist by E46, and those from the contralateral hemisphere, claustrum, putamen, and central lateral nucleus of the thalamus are present by E54–E56. In addition, cells in the medial geniculate nucleus project to auditory cortex by E55. At E54–E56 efferent cortical projections reach the contralateral hemisphere, claustrum, putamen, lateral-posterior/pulvinar complex and reticular nucleus of the thalamus. Cells in visual cortex also project to the dorsal and ventral lateral geniculate nuclei, pretectum, superior colliculus and pontine nuclei, and cells in auditory cortex project to the medial geniculate nucleus. Except for interhemispheric projections, all pathways demonstrated are ipsilateral, and projections linking cerebral cortex with claustrum, dorsal lateral geniculate nucleus and lateral-posterior/pulvinar complex are reciprocal. The reciprocal projections formed with the dorsal lateral geniculate nucleus, lateral-posterior/pulvinar complex and the claustrum show a greater degree of topological organization compared to the projections formed with the contralateral hemisphere and superior colliculus, which show little or no topological order. Therefore, the results of the present study show that the major extrinsic projections of the cat's visual and auditory cortical areas with subcortical structures are present by the eighth week of gestation, and that the origins and terminations of many of these projections are arranged topologically.

Projections of the retinorecipient pretectal nuclei in the pigeon (Columba livia).

We have used anterograde autoradiographic and retrograde HRP techniques to investigate the efferent connections of the retinorecipient pretectal nuclei in the pigeon. In the accompanying paper we identified these nuclei in the pigeon as the nucleus lentiformis mesencephali--pars lateralis and pars medialis, the tectal gray, the area pretectalis, and pretectalis diffusus. Although there are reports of a few of the projections of these nuclei, they had not previously been the subject of a detailed study. We found that different cell types in the lentiformis mesencephali, pars medialis and the lentiformis mesencephali, pars lateralis have descending projections to different targets. These targets include the inferior olive, the cerebellum, the lateral pontine nucleus, the nucleus papillioformis, the nucleus of the basal optic root, the nucleus mesencephalicus profundus, pars ventralis, the nucleus principalis precommissuralis, and the stratum cellulare externum. We found that a few cells in the lentiformis mesencephali project to the medial pontine nucleus, but that a much heavier projection arises from the nucleus laminaris precommissuralis, which is medial to the nucleus lentiformis mesencephali, pars medialis. The tectal gray has predominantly ascending projections to the diencephalon. The nuclei that it projects to are the nucleus intercalatus thalami, the nucleus of the ventral supraoptic decussation, the nucleus posteroventralis, the ventral lateral geniculate nucleus, the nucleus dorsolateralis medialis, and the nucleus dorsolateralis anterior. The tectal gray also projects topographically to layers 4 and 8-13 of the optic tectum. Area pretectalis has both ascending and descending projections. It has ipsilateral ascending projections to the nucleus dorsolateralis anterior, pars magnocellularis, the nucleus lateralis anterior, and the nucleus ventrolateralis thalami. It has ipsilateral descending projections to the central gray, the nucleus of the basal optic root, pars dorsalis, the lateral pontine nucleus, and the deep layers of the optic tectum. It has contralateral projections to the area pretectalis, the nucleus Campi Foreli, the interstitial nucleus of Cajal, the nucleus of Darkschewitsch, the cerebellum, and the Edinger-Westphal nucleus. The efferent projections of pretectalis diffusus are limited. It projects contralaterally to the pretectalis diffusus, and ipsilaterally to the nucleus of the ventral supraoptic decussation, the lateral pons, and the cerebellum.4

Smooth-pursuit eye movement deficits with chemical lesions in the dorsolateral pontine nucleus of the monkey.

1. Anatomical and single-unit recording studies suggest that the dorsolateral pontine nucleus (DLPN) in monkey is a major link in the projection of descending visual motion information to the cerebellum. Such studies coupled with cortical and cerebellar lesion results suggest a major role for this basilar pontine region in the mediation of smooth-pursuit eye movements. 2. To provide more direct evidence that this pontine region is involved in the control of smooth-pursuit eye movements, focal chemical lesions were made in DLPN in the vicinity of previously recorded visual motion and pursuit-related neurons. Eye movement responses were subsequently recorded in these lesioned animals under several behavioral paradigms. 3. A major deficit in smooth-pursuit performance was produced after unilateral DLPN lesions generated either reversibly with lidocaine or more permanently with ibotenic acid. Pursuit impairments were observed during steady-state tracking of sinusoidal target motion as well as during the initiation of pursuit tracking to sudden ramp target motion. Through the use of the latter technique, initial eye acceleration was reduced to less than one-half of normal for animals with large lesions of the dorsolateral and lateral pontine nuclei. 4. The pursuit deficit in all animals was directional in nature and was not dependent on the visual hemifield in which the motion stimulus occurred. The largest effect for horizontal tracking occurred in all animals for pursuit directed ipsilateral to the lesion. Animals also showed major deficits in one or both directions of vertical pursuit, although the primary direction of the vertical impairment was variable from animal to animal. 5. Chemical lesions in the DLPN also produced comparable deficits in the initiation of optokinetic-induced smooth eye movements in the ipsilateral direction. In contrast to this effect on the initial optokinetic response, in the one lesioned animal studied during prolonged constant velocity optokinetic drum rotation, smooth eye speed increased slowly over a 10- to 15-s period to reach a level that closely matched drum speed. These results suggest that pathways outside the DLPN can generate the steady-state optokinetic response. 6. Saccades to stationary targets were normal after DLPN lesions, but corrective saccades made to targets moving in the direction ipsilateral to the lesion were much more hypometric than similar prelesion control saccades. 7. The pursuit deficits produced by lidocaine injections recovered within 30 min. The ibotenic acid deficits were maximal approximately 1 day after the injection and recovered rapidly thereafter over a time period of 3-7 days.(ABSTRACT TRUNCATED AT 400 WORDS)

Descending projections from the superior colliculus in rat: a study using orthograde transport of wheatgerm-agglutinin conjugated horseradish peroxidase.

Despite extensive behavioural work on the rat superior colliculus, its descending efferent pathways have not been fully characterised with modern anatomical tract-tracing techniques. To investigate these pathways, wheatgerm-agglutinin conjugated with horseradish peroxidase (1%) was injected at various locations within the superior colliculus of hooded rats. Label judged to be transported orthogradely was plotted on coronal sections modified from the atlas of Paxinos and Watson (1982). Two major descending pathways were identified. (i) The bulk of the fibres in the ipsilateral descending pathway leave the superior colliculus ventrolaterally, and course around the lateral margin of the midbrain reticular formation. Caudally, projecting fibres leave the main bundle to innervate the cuneiform nucleus, and parts of the pontomedullary reticular formation. Terminal fields associated with the major bundle of fibres are found in an area medial to the brachium of the inferior colliculus; the parabigeminal nucleus and adjacent tegmentum; the ventrolateral midbrain reticular formation; and the lateral pontine nuclei. (ii) The fibres of the main contralateral descending pathway leave the superior colliculus ventromedially, to cross midline in the dorsal tegmental decussation. They immediately turn caudally to join the predorsal bundle, in which they run the length of the brainstem to reach the cervical spinal cord. Major terminal fields occur in nucleus reticularis tegmenti pontis; the pedunculopontine/parabrachial area; paramedian pontomedullary reticular formation; and inferior olive. In addition there is lighter labelling in many areas of the pontomedullary reticular formation and in the cervical spinal cord. There was also a much sparser contralateral descending projection that crossed midline in the tectal commissure, and sent terminals to the contralateral cuneiform area and adjoining regions. These results suggest that the distribution of the descending efferent pathways from the superior colliculus in rats is similar to those described in other species. The fact that the two major pathways project to quite different terminal areas, together with previous findings that they have separate cells of origin within the tectum, suggests that they may also be functionally distinct.

Adult rat motor cortex connections to thalamus following neonatal and juvenile frontal cortical lesions: WGA-HRP and amino acid studies

Frontal cortex was removed in 1- and 30-day-old rats. When both groups reached 90 days of age, the forelimb motor/sensory cortex in the unlesioned hemisphere was injected with wheat germ agglutinin-horseradish peroxidase (WGA-HRP) or tritiated leucine. Thalamic neurons were retrogradely labeled only ipsilateral to the WGA-HRP injection site in both neonatally and juvenile-lesioned subjects. Ventrolateral (VL), ventromedial (VM), centromedial (CM), centrolateral (CL), parafascicular (PF), posteromedial (POm), and posterior (PO) thalamic nuclei were labeled. This and the demonstration of only ipsilateral thalamocortical connections at birth helped explain the marked thalamic atrophy which developed ipsilateral to neonatal frontal cortex lesions. Death of thalamic neurons after neonatal removal of their normal cortical target could be due to their failure to sprout into the opposite cortex because that cortex was already innervated by the opposite thalamus at birth. Leucine motor/sensory cortex injections in both neonatally and juvenile-lesioned subjects labeled the ipsilateral VL, VM, CM, CL, PF, POm, and PO thalamic nuclei; contralateral CM, CL, and PF thalamic nuclei; ipsilateral medial, ventral, and lateral pontine nuclei; and parts of the contralateral pontine nuclei. The ipsilateral connections were always more robust than the contralateral connections. The contralateral corticothalamic and corticopontine projections, however, were much more numerous and widespread in neonatally compared to juvenile-lesioned subjects. The greater sparing of some motor functions said to occur in neonatal compared to adult motor cortex-lesioned subjects could be due to the plasticity of corticothalamic, corticopontine, and other corticofugal pathways, but not to the plasticity of thalamocortical pathways.

Adult rat motor cortex connections to thalamus following neonatal and juvenile frontal cortical lesions: WGA-HRP and amino acid studies.

Frontal cortex was removed in 1- and 30-day-old rats. When both groups reached 90 days of age, the forelimb motor/sensory cortex in the unlesioned hemisphere was injected with wheat germ agglutinin-horseradish peroxidase (WGA-HRP) or tritiated leucine. Thalamic neurons were retrogradely labeled only ipsilateral to the WGA-HRP injection site in both neonatally and juvenile-lesioned subjects. Ventrolateral (VL), ventromedial (VM), centromedial (CM), centrolateral (CL), parafascicular (PF), posteromedial (POm), and posterior (PO) thalamic nuclei were labeled. This and the demonstration of only ipsilateral thalamocortical connections at birth helped explain the marked thalamic atrophy which developed ipsilateral to neonatal frontal cortex lesions. Death of thalamic neurons after neonatal removal of their normal cortical target could be due to their failure to sprout into the opposite cortex because that cortex was already innervated by the opposite thalamus at birth. Leucine motor/sensory cortex injections in both neonatally and juvenile-lesioned subjects labeled the ipsilateral VL, VM, CM, CL, PF, POm, and PO thalamic nuclei; contralateral CM, CL, and PF thalamic nuclei; ipsilateral medial, ventral, and lateral pontine nuclei; and parts of the contralateral pontine nuclei. The ipsilateral connections were always more robust than the contralateral connections. The contralateral corticothalamic and corticopontine projections, however, were much more numerous and widespread in neonatally compared to juvenile-lesioned subjects. The greater sparing of some motor functions said to occur in neonatal compared to adult motor cortex-lesioned subjects could be due to the plasticity of corticothalamic, corticopontine, and other corticofugal pathways, but not to the plasticity of thalamocortical pathways.

Classical conditioning of the rabbit eyelid response with a mossy-fiber stimulation CS: I. Pontine nuclei and middle cerebellar peduncle stimulation.

The nictitating membrane/eyelid responses of 18 rabbits were classically conditioned using cerebellar mossy-fiber stimulation as a conditioned stimulus (CS) and air puff as an unconditioned stimulus (US). The dorsolateral, lateral, and medial pontine nuclei and the middle cerebellar peduncle were effective stimulation-CS sites for training. In one group of rabbits, robust conditioned eyelid responses were produced with paired trials and subsequently extinguished with CS-alone and explicitly unpaired presentation of the CS and US. In a second group of rabbits, no conditioned responses were evident for 4 days of unpaired CS and US presentations. Conditioned responses did develop, however, after paired training was begun. Lesions of the interpositus nucleus of the cerebellum completely abolished the conditioned responses of a third group of rabbits overtrained with the mossy-fiber CS and air-puff US. These results support previous studies which have demonstrated that the cerebellum is critically involved in acquisition and retention of simple learned responses. In addition, the present results support previous theories of cerebellar function which have proposed that mossy fibers supply critical "learning" input to the cerebellum for acquisition and retention of motor skills.

Cells of origin of spinopontine fibers in the rat

When wheat germ agglutinin-horseradish peroxidase conjugate was injected into the caudal part of the medial, lateral, ventral and peduncular pontine nuclei in the rat, retrogradely labeled spinal neurons were found contralaterally in the intermediate basilar nucleus (IBN) in the upper two cervical cord segments, and in laminae VI and VII in the lumbar cord segments. The IBN appeared to send fibers mainly to the caudomedial part of the pontine nuclei, while laminae VI and VII of the lumbar cord segments of the caudolateral part of the pontine nuclei.

Regional (14C) 2‐deoxyglucose uptake during forelimb movements evoked by rat motor cortex stimulation: Pons, cerebellum, medulla, spinal cord, muscle

Electrical stimulation of the right forelimb motor (MI) sensory (SI) cortex in normal, adult rats produced repetitive left forelimb movements. Regions of increased (14C) 2-deoxyglucose (2DG) uptake were mapped auto-radiographically during these movements. MI stimulation activated the ipsilateral reticular tegmental pontine nucleus (RTP) and the middle (rostral-caudal) third of the pontine nuclei including pyramidal (P), medial (POM), ventral (POV), and lateral (POL) pontine nuclei. The ipsilateral inferior olivary complex was activated including dorsal accessory olive (DAO), principal olive (PO), and medial accessory olive (MAO). The contralateral lateral reticular (LR) nucleus and nucleus cuneatus (CU) were activated. Lateral vermal, paravermal, and hemispheric portions of the contralateral cerebellum were also activated. Parts of vermian lobules IV, V, VI, VII, and VIII, and lobulus simplex, crus I, crus II, paramedian lobule, and copula pyramidis were activated. Granule cell layers were activated much more than molecular layers. Discrete microzones of high granule cell 2DG uptake alternated with zones of low uptake in left paramedian lobule and copula pyramidis and may correlate with the fractured cerebellar somatotopy described physiologically by Welker and his associates. Portions of the left lateral and interpositus nuclei were metabolically activated. Medial portions of laminae I-VI were activated in the dorsal horn of cervical spinal cord. The 2DG uptake was either unchanged or decreased in the ventral horn. Thoracic and lumbar spinal cord were not activated. Monsynaptic MI and SI connections to P, POM, POV, POL, RTP, DAO, PO, MAO, LR, CU, and spinal cord could account for activation of those structures. However, there are no direct MI or SI connections to the deep cerebellar nuclei, the cerebellar hemisphere, or the muscles. Activation of these structures must be due to activation of polysynaptic pathways, sensory feedback from the moving forelimb, or both. The present experiments cannot distinguish these possibilities. Comparison of the regions activated during forelimb MI stimulation (FLMIS) to those activated during vibrissae MI stimulation (VMIS) suggests that the pontine nuclei, cerebellar hemisphere, and possibly the deep cerebellar nuclei are somatotopically organized. RTP, LR, CU, and spinal cord were activated during FLMIS but were not activated during VMIS. The failure to activate the ventral horn of cervical spinal cord may be due to known inhibition of alpha-motor neurons during motor cortex stimulation.

Autoradiographic demonstration of retinal projections to the brain stem structures in the rabbit using transneuronal tracing technique with special reference to the retinal projections to the inferior olive

Retinal projections to the brain stem structures in the rabbit were examined autoradiographically using transneuronal tracing technique. Three or four weeks after intraocular injections of tritiated proline and tritiated fucose, significant amounts of silver grains indicating transneuronal labeling of axon terminals were present bilaterally in the visual cortical areas, the dorsal portions of the medial geniculate nucleus, and the suprageniculate nucleus, and contralaterally in the thalamic reticular nucleus, the lateroposterior-pulvinar nuclear complex, the parabigeminal nucleus, the pontine tegmental reticular nucleus of Bechterew, the dorsolateral, lateral, and paramedian pontine nuclei, the pontine reticular formation, and the dorsal cap and beta nucleus of the inferior olive. The label in the pontine regions was probably due to the afferent fibers from the pretectal nuclei and the superior colliculus, and the label in the inferior olive was considered to depend on the uncrossed afferent fibers from the pretectal nuclei and the nuclei of the accessory optic tract.

Regional (14C) 2-deoxyglucose uptake during vibrissae movements evoked by rat motor cortex stimulation.

Repetitive left mystacial vibrissae movements were produced by electrical stimulation of right motor cortex (MI) were a bipolar electrode in the alert, unanesthetized rat. Regional increases of (14C) 2-deoxyglucose (2DG) uptake were mapped autoradiographically during these left vibrissae movements. Uptake of 2DG increased in a 2-4-mm-diameter area about the stimulating electrode in right MI and in a smaller region in left MI cortex. Columnar increases of 2DG uptake occurred bilaterally in somatosensory cortex in the face region of somatosensory cortex (SI). Bilateral increases of 2DG uptake occurred subcortically in dorsolateral caudate-putamen (CP) and subthalamic nucleus. Primary right-sided increases of 2DG uptake occurred in other basal ganglia structures including dorsal globus pallidus (GP), posterior, entopeduncular nucleus (EPN), ventrolateral substantia nigra pars reticulata (SNr), and anterolateral substantia nigra pars compacta (SNc). Uptake of 2DG increased on the right side of the following thalamic regions: much of the ventrolateral (VL) nucleus, particularly dorsally; the anterodorsal reticular nucleus; dorsolateral posteromedial (POm) nucleus; the ventromedial nucleus; and dorsolateral parafasicular nucleus. The anterior and ventral posterior portions of VL were not activated. Caudal to thalamus right-sided 2DG uptake increased in the medial, ventral, and lateral pontine nuclei, deep layers of superior colliculus, lateral deep mesencephalic nucleus (DMN), and nucleus cuneiformis (NCU). UPtake of 2DG increased in right rostral parvocellular and red nucleus in a few animals. Discrete portions of the right internal capsule and right medial pyramidal tract increased 2DG uptake during MI stimulation. Uptake of 2DG increased on the left side of the brain during right MI stimulation in the left lateral nucleus (NL) of cerebellum and in several discrete regions of left cerebellar hemisphere granule cells including anterior paravermis, lobulus simplex, crus II, and the paramedian lobule. Uptake of 2DG increased in left nucleus of the spinal tract of the trigeminal nerve (ntV) ventrally in subnuclei interpolaris and oralis. Left lateral portions of the facial nucleus were activated in a few animals. The lateral portions of the facial nucleus are known to project to vibrissae musculature. All of the above structures may be involved in the motor-sensory processing responsible for vibrissae movements. Regions not previously suggested to play a major role in vibrissae movements include DMN and NCU. Though NCU has been called the "locomotor center" it may play a role in facial movements as well. Polysynaptic activation of GP, EPN, NL, and cerebellar hemisphere occurred since no connections between MI and these regions exist. A pathway from ntV to POm to MI and SI is suggested to provide proprioceptive input to motor-sensory cortex from the moving vibrissae since neither the principal trigeminal sensory nucleus nor the ventrobasal nucleus of the thalamus increased 2DG uptake during MI stimulation.

Laminar distribution of the cells of origin of the descending tectofugal pathways in the pigeon (Columba livia).

AbstractThe horseradish peroxidase (HRP) technique was used to investigate the laminar distribution of the cell bodies of origin of the two major descending pathways from the avian tectum to the hindbrain, the crossed tectobulbar pathway (CTB) and the ipsilateral tectopontine‐tectoreticular pathway (ITP). The CTB, which projects to the contralateral paramedian reticular formation of the hindbrain, was found to arise mainly (80–95%) from the large multipolar neurons characteristic of layer 13 of the tectum. In addition, multipolar neurons of layers 14 and 15 of the dorsal tectum contribute to rostrally terminating portions of the CTB. Neurons of layers 11–12, particularly at rostroventral tectal levels, were also found to contribute to the CTB. The ITP, which projects to the ipsilateral lateral pontine nucleus and the overlying reticular formation, was found to arise chiefly from neurons of layers 9–10, 13, and 14–15, with some slight contributions from neurons of tectal layers 8, 11, and 12. Cells of layers 8–10 that contributed to the ITP tended to be of two general types: (1) small‐mediumsized fusiform neurons with vertically disposed processes, and (2) medium‐large‐sized multipolar neurons whose processes showed no consistent orientation from neuron to neuron. The lateral pontine nucleus apparently receives input from tectal layers 8–15 inclusive, while the reticular formation overlying the lateral pontine nucleus appears to receive input only from tectal layers 13–15. Injections of HRP into the CTB and ITP also resulted in labeled cells in subtectal sites within the optic lobe (nucleus intercollicularis and the lateral mesencephalic reticular formation).The present results indicate that the major descending projections of the avian tectum arise from neurons located in tectal layers 8–15. Previous studies have shown that neurons of tectal layers 10 and 13–14 also give rise to the ascending projections of the avian tectum to the ventral lateral geniculate nucleus and to the nucleus rotundus, respectively (Benowitz and Karten, '76; Hunt and Kunzle, '76b). Thus, the major ascending and descending tectofugal pathways in birds share the same layers of origin. The present results in birds are in contrast to those in mammals, in which the ascending projections of the midbrain roof to diencephalic “visual” structures arise from superficial layers of the superior colliculus (layers I–III) while the major descending projections arise largely from the deeper layers of the superior colliculus (Harting et al., '73; Holcombe and Hall, '81). The decending pathways of the midbrain roof are presumed to be involved in motor functions while the ascending pathways of the midbrain roof are thought to be more involved in the sensory processing of visual information. The similarity in the laminar sources of the ascending and descending tectofugal pathways in birds, as reflected by the present study, indicates that the asending and desending tectofugal pathways of birds may convey similar types of visual information.

Visual and pursuit eye movement-related activity in posterior vermis of monkey cerebellum.

Visual and pursuit eye movement-related activity in posterior vermis of monkey cerebellum.D A Suzuki, H Noda, and M KaseD A Suzuki, H Noda, and M KasePublished Online:01 Nov 1981https://doi.org/10.1152/jn.1981.46.5.1120MoreSectionsPDF (3 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInEmailWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformationCited ByPursuit disorder and saccade dysmetria after caudal fastigial inactivation in the monkeyClara Bourrelly, Julie Quinet, and Laurent Goffart2 October 2018 | Journal of Neurophysiology, Vol. 120, No. 4The superior colliculus and the steering of saccades toward a moving visual targetLaurent Goffart, Aaron L. Cecala, and Neeraj J. Gandhi7 November 2017 | Journal of Neurophysiology, Vol. 118, No. 5Responses of Purkinje cells in the oculomotor vermis of monkeys during smooth pursuit eye movements and saccades: comparison with floccular complexRamanujan T. Raghavan and Stephen G. Lisberger1 August 2017 | Journal of Neurophysiology, Vol. 118, No. 2Synchronizing the tracking eye movements with the motion of a visual target: Basic neural processesLearning the trajectory of a moving visual target and evolution of its tracking in the monkeyClara Bourrelly, Julie Quinet, Patrick Cavanagh, and Laurent Goffart1 December 2016 | Journal of Neurophysiology, Vol. 116, No. 6Visual Pathways Serving Motion Detection in the Mammalian Brain1 April 2010 | Sensors, Vol. 10, No. 4Role of Primate Cerebellar Hemisphere in Voluntary Eye Movement Control Revealed by Lesion EffectsMasafumi Ohki, Hiromasa Kitazawa, Takahito Hiramatsu, Kimitake Kaga, Taiko Kitamura, Jinzo Yamada, and Soichi Nagao1 February 2009 | Journal of Neurophysiology, Vol. 101, No. 2Common Inhibitory Mechanism for Saccades and Smooth-Pursuit Eye MovementsM. Missal, and E. L. Keller1 October 2002 | Journal of Neurophysiology, Vol. 88, No. 4Purkinje Cells of the Cerebellar Dorsal Vermis: Simple-Spike Activity During Pursuit and Passive Whole-Body RotationYasuhiro Shinmei, Takanobu Yamanobe, Junko Fukushima, and Kikuro Fukushima1 April 2002 | Journal of Neurophysiology, Vol. 87, No. 4Cerebellar Flocculus and Ventral Paraflocculus Purkinje Cell Activity During Predictive and Visually Driven Pursuit in MonkeyM. Suh, H.-C. Leung, and R. E. Kettner1 October 2000 | Journal of Neurophysiology, Vol. 84, No. 4Smooth-Pursuit Eye-Movement Deficits With Chemical Lesions in Macaque Nucleus Reticularis Tegmenti PontisDavid A. Suzuki, Tetsuto Yamada, Rebecca Hoedema, and Robert D. Yee1 September 1999 | Journal of Neurophysiology, Vol. 82, No. 3Role of the Oculomotor Vermis in Generating Pursuit and Saccades: Effects of MicrostimulationR. J. Krauzlis, and F. A. Miles1 October 1998 | Journal of Neurophysiology, Vol. 80, No. 4Participation of Caudal Fastigial Nucleus in Smooth Pursuit Eye Movements. II. Effects of Muscimol InactivationFarrel R. Robinson, Andreas Straube, and Albert F. Fuchs1 August 1997 | Journal of Neurophysiology, Vol. 78, No. 2Prearcuate cortex in the cebus monkey has cortical and subcortical connections like the macaque frontal eye field and projects to fastigial-recipient oculomotor-related brainstem nucleiBrain Research Bulletin, Vol. 41, No. 1Posterior vermal Purkinje cells in macaques responding during saccades, smooth pursuit, chair rotation and/or optokinetic stimulationNeuroscience Research, Vol. 12, No. 5Generation of smooth-pursuit eye movements: neuronal mechanisms and pathwaysNeuroscience Research, Vol. 11, No. 2Auditory receptive area in the cerebellar hemisphere is surrounded by somatosensory areasBrain Research, Vol. 541, No. 2Target areas of presumed auditory projections from lateral and dorsolateral pontine nuclei to posterior cerebellar vermis in ratBrain Research, Vol. 536, No. 1-2Inhibitory action of Purkinje cells in the posterior vermis on fastigio-prepositus circuit of the catBrain Research, Vol. 455, No. 1Morphological and behavioral markers of environmentally induced retardation of brain development: an animal model.Environmental Health Perspectives, Vol. 74Biological image motion processing: A reviewVision Research, Vol. 25, No. 5Membrane resistivity estimated for the purkinje neuron by means of a passive computer modelNeuroscience, Vol. 14, No. 1Cerebellar vermis involvement in monkey saccadic eye movements: MicrostimulationExperimental Neurology, Vol. 86, No. 3Space-time representation in the brain. The cerebellum as a predictive space-time metric tensorNeuroscience, Vol. 7, No. 12The tecto-olivo-cerebellar pathway in the ratBrain Research, Vol. 250, No. 1 More from this issue > Volume 46Issue 5November 1981Pages 1120-39 https://doi.org/10.1152/jn.1981.46.5.1120PubMed7299450History Published online 1 November 1981 Published in print 1 November 1981 Metrics

Neuronal death and the development of the pontine nuclei and inferior olive in the chick

The cerebellar inputs from the chick's inferior olive and medial pontine nucleus are largely or entirely crossed, and those from the lateral pontine nucleus are partly (probably more than 50%) crossed. The neurons of these cell groups leave their last generation cycle between stages 20–25 (inferior olive); stages 24–29 (medial pontine nucleus); and stages 25–30 (lateral pontine nucleus). During normal development, about one-third of the cells in the inferior olive are lost, presumably through their death, over the 4 days before hatching; this corresponds to the previously demonstrated time of induced cell loss in the olive following cerebellar lesions. There is normally no cell loss, however, in the developing pontine nuclei. The absence of cell death in the pontine nuclei is of special interest, since this is the first report of such an absence for a brain nucleus. It may be due to the great abundance of potential synaptic sites available to the mossy fibres from the pons. All this lends weight to the view that for a neuron to survive during normal development it is more critically important for its axon to make synapses than for its dendrites and soma to receive synapses.

Acoustic input to the lateral pontine nuclei

Axon and terminal degeneration were studied in the cat dorsolateral pontine nucleus (DLPN) after lesion of the inferior colliculus. In separate experiments the acoustic responses of 111 units of the lateral pontine nuclei were studied in cats anesthetized with chloralose-urethane. Lesions of all three nuclei of the inferior colliculus (central, pericentral and external) lead to a very similar pattern of terminal degeneration in a discrete region of ipsilateral DLPN. This is suggestive of a highly convergent projection in which topography may be blurred. Most units responded to binaural stimulation, and the most common binaural response consisted of xcitatory inputs from each ear which facilitatyed at some binaural intensity levels and occuluded at others. Discharge rates changed as a result of alterations in the number of spikes evoked at the onset of the stimulus, and sustained discharges were rarely encountered. Units broadly and irregularyly tuned; binaural inhibition was very uncommon. Unit response characteristics suggested that, while the projection from the inferior colliculus was highly convergent, only a subclass of inferior colliculus neurons may be involved. However, the acoustic properties of lateral pontine units were strikingly similar to those of the cerebellar vermis, a region to which DLPN is known to project.

The pontocerebellar projection of the uvula in the cat.

The occurrence of retrogradely labeled cells in the pontine nuclei was mapped following injections of 0.3-0.4 microliter of a horseradish peroxidase suspension (50% weight/volume) into the uvula (lob. IX of Larsell) in the cat. The uvula was found to receive afferents from three pontine cell collections. One of these is situated in the paramedian pontine nucleus close to the midline. It forms a fairly distinctly outlined longitudinal column of cells and is present at all levels of the pons except most rostrally and caudally. Another group, in the dorsolateral and lateral pontine nuclei, extends as a somewhat shorter cell column in the longitudinal direction. The third region consists of cells within the rostral part of the peduncular nucleus in its dorsomedial region. The pontine projection to the uvula is bilateral, with some preponderance of crossed connections. The projection to the uvula is organized according to the pattern determined previously for pontine projections to other parts of the cerebellum. A single lobule or part of its receives afferents from more than one cell group in the pons. The projecting cells are most often arranged in longitudinal columns. Correlations with data on the termination of afferents to the pons permit some conclusions regarding the sources of information reaching the uvula via the pons. Main sources seem to be the superior and inferior colliculi, the intracerebellar nuclei and the sensorimotor cortices.

Some visual and other connections to the cerebellum of the pigeon.

By anatomical techniques it has been shown that folia VIc-IXc of the pigeon cerebellum receive inputs from the following groups of neurons: the medial and lateral pontine nuclei, the superficial synencephalic nucleus, the medial spiriform nucleus, the inferior olive, and the deep cerebellar nuclei. From all but the last of these, the projection is mainly crossed, though the uncrossed component from the lateral pontine nucleus is not insubstantial. The input from the superficial synencephalic nucleus provides a direct pathway from the retina to the cerebellum (folia VIc, VII, VIII and IXc). Less direct visual pathways reach the cerebellum via the following routes: (i) the superficial synencephalic nucleus projects ipsilaterally to the lateral pontine nucleus and sparsely to the inferior olive; (ii) the tectum projects ipsilaterally to the lateral and medial pontine nuclei, though the latter connection is sparse. In electrophysiological experiments, the importance of the tecto-pontine component of the projection has been demonstrated by cooling the tectum while recording visual responses from the cerebellum. The visual receptive fields of pontine cells have been analysed. They vary in extent from 10 degrees to the whole monocular field. They respond best to moving targets, preferring speeds of 20 to 60 degrees/second, and are usually direction-selective.

The pontine projection to the cerebellar vermal visual area studied by means of the retrograde axonal transport of horseradish peroxidase

Following injections of horseradish peroxidase (HRP) in cerbellar vermal lobules VI, VIIA and B, VIIA and B in the cat, the distribution of labeled cells in the pontine nuclei was mapped in drawings of serial transverse and horizontal sections. The labeled pontine cells are distributed in 4 largely longitudinal columns, situated in the dorsolateral, peduncular, lateral and paramedian pontine nucleus (referred to as columns A, B, C and D, respectively). The majority of afferents to the vermal, visual areas come from colums A and B. To some extent cells projecting to the various sublobules have their preferential location within each column (Fig. 5). The majority of the fibers end in lobule VII. Available data from the literature show that only columns A, D and rostral part of B may be involved in the transmission of visual impulses to the vermal area, since these columns receive afferents from the superior colliculus, the lateral geniculate body and the visual cortex, respectively. The route via the superior colliculus-dorsolateral nucleus appears to be quantitatively the most important. As judged from data on fiber connections, impulses from various sources (inferior colliculus, cerebellar nuclei and "non-visual" parts of the cerebral cortex) are transmitted to certain parts of the 4 columns. The functional importance of this convergence and some general features in the organization of the pons are discussed.