Valence processing in pons.

In this issue of Neuron, Xiao et al.1 reported that inhibitory and excitatory neurons in the pontine central gray encode and transmit opposite valences of sensory stimuli through parallel circuits to a distributed brain network.

Sixteen syndrome: a rare presentation of central demyelination.

This case illustrates two diagnostic challenges for clinicians: the rarely described sixteen syndrome and the relationship between tumour necrosis factor (TNF)-alpha inhibitors and central demyelination. Sixteen syndrome affects horizontal eye movements and the facial nerve bilaterally reflecting a lesion in the posterior pontine tegmentum, adjacent to the fourth ventricle. Given its rarity and complexity of clinical signs, this syndrome risks misdiagnosis and mismanagement. The relationship between TNF-alpha inhibitors and demyelination is a complex issue in which causality is yet to be established. This diagnostic challenge poses a management dilemma for clinicians.

Excitatory SST neurons in the medial paralemniscal nucleus control repetitive self-grooming and encode reward.

The use of body-focused repetitive behaviors (BFRBs) is conceptualized as a means of coping with stress. However, the neurological mechanism by which repetitive behaviors affect anxiety regulation is unclear. Here, we identify that the excitatory somatostatin-positive neurons in the medial paralemniscal nucleus (MPL^SST neurons) in mice promote self-grooming and encode reward. MPL^SST neurons display prominent grooming-related neuronal activity. Loss of function of MPL^SST neurons impairs both self-grooming and post-stress anxiety alleviation. Activation of MPL^SST neurons is rewarding and sufficient to drive reinforcement by activating dopamine (DA) neurons in the ventral tegmental area (VTA) and eliciting dopamine release. The neuropeptide SST facilitates the rewarding impact of MPL^SST neurons. MPL^SST neuron-mediated self-grooming is triggered by the input from the central amygdala (CeA). Our study reveals a dual role of CeA-MPL^SST-VTA^DA circuit in self-grooming and post-stress anxiety regulation and conceptualizes MPL^SST neurons as an interface linking the stress and reward systems in mice.

Pedunculo-pontine tegmentum cholinergic REM-ON neurons modulate ventral tegmental neurons to modulate rapid eye movement sleep in rats.

The interaction among the acetylcholine (ACh)-ergic REM-ON neurons in the pedunculo-pontine area (PPT), noradrenergic REM-OFF neurons in locus coeruleus (LC) and GABA-ergic neurons in the regulation of rapid eye movement sleep (REMS) have been studied in relative details; however, many questions including the role of dopamine (DA) remain unanswered. The ventral tegmental area (VTA) is rich in DA-ergic neurons, which have been implicated with schizophrenia and depression, when REMS is significantly affected. Also, some of the symptoms of REMS and these diseases are common. As the ACh-ergic REM-ON neurons in the PPT project to VTA, we proposed that such inputs might affect REMS, dreams and hallucinations. We recorded sleep-wake-REMS in freely moving, chronically prepared rats under three controlled experimental conditions. In different sets of experiments, either the ACh-ergic inputs to the VTA were blocked by local microinjection of Scopolamine (Scop) alone, or, the PPT neurons were bilaterally stimulated by Glutamate (Glut), or, the PPT neurons were stimulated by Glut in presence of Scop into the VTA. It was observed that Glut into PPT and Scop into the VTA significantly increased and decreased REMS, respectively. Additionally, PPT stimulation induced increased REMS was prevented in the presence of Scop into the VTA. Based on these findings we propose that inputs from ACh-ergic REM-ON neurons to VTA increase REMS and it could be a possible circuitry for expressions of hallucinations and dreams.

Bilateral facial colliculus syndrome caused by pontine tegmentum infarction: a case report.

BACKGROUND: Bilateral facial colliculus syndrome is a rare clinical presentation in patient with pontine infarction. We herein described a case of bilateral facial paralysis and complete horizontal gaze palsy possibly caused by paradoxical embolization from patent foramen ovale related stroke. CASE PRESENTATION: A 55-year-old male presented with sudden onset of complete peripheral facial palsy and horizontal gaze palsy after Valsava maneuver. MRI revealed symmetric involvement of bilateral pontine tegmentum in accordance with the location of facial colliculus. CSF analysis and follow-up MRI showed no evidence of central demyelinating disease. Subsequent echocardiography revealed patent foramen ovale and closure surgery was performed. CONCLUSIONS: Facial colliculus syndrome with symmetric dorsal pontine tegmentum involvement may a rare manifestation in posterior circulation stroke.

Oftalmoplejía internuclear bilateral (WEBINO) en un paciente pediátrico con Lupus Eritematoso Sistémico / Wall-eyed bilateral internuclear ophthalmoplegia (WEBINO) in a pediatric patient with Systemic Lupus Erythematosus

Resumen El síndrome de WEBINO (wall-eyed bilateral internuclear ophthalmoplegia), se presenta por una lesión del tegmento pontino (incluye área pontina paramediana, fascículo longitudinal medial y núcleo del abducens). Presenta limitación bilateral en la aducción y exotropía en la posición de la mirada primaria, nistagmo del ojo que abduce e incapacidad para la convergencia. Reporte de caso: Presentamos el caso de una paciente de 14 años con antecedente de Lupus Eritematoso Sistémico que debutó con diplopía horizontal de inicio súbito. El diagnóstico de WEBINO fue clínico y asociado con hallazgos de lesión isquémico pontomesencefálica en Resonancia Nuclear Magnética y angioresonancia cerebral. Se administró tratamiento con Metilprednisolona y presentó resolución gradual de los síntomas, sin embargo una semana después falleció por criptococosis sistémica. Conclusiones: Hacer el diagnostico de WEBINO se hace desafiante por su rareza y por la precisión de su localización neuroanatómica. Se debe realizar una exploración detallada para definir la causa probable y establecer el tratamiento oportuno que favorezca el pronóstico neurológico.

Background: Wall-eyed bilateral internuclear ophthalmoplegia (WEBINO) is presented by a lesion of the pontine tegment (includes paramedian pontine area, medial longitudinal fascicle and nuclei of the abducens). It presents bilateral limitation in adduction and exotropia in the position of the primary gaze, abducting eye nystagmus and inability to converge. Case report: We present the case of a 14-year-old patient with a history of Systemic Lupus Erythematosus who debuted with sudden onset horizontal diplopia. WEBINO's diagnosis was clinical and associated with findings of ponto-mesencephalic ischemic injury in magnetic resonance imaging and magnetic resonance angiography. Treatment with Methylprednisolone was administered and she presented gradual resolution of the symptoms, however, one week later she died of systemic cryptococcosis. Conclusions: Making the WEBINO diagnosis is challenging due to its rarity and the precision of its neuroanatomical location. A detailed examination should be performed to define the probable cause and establish the appropriate treatment that favors the neurological prognosis.

Dopaminergic- and cholinergic-inputs from substantia nigra and pedunculo-pontine tegmentum, respectively, converge in amygdala to modulate rapid eye movement sleep in rats.

Dreams appear intermittently during phasic rapid eye movement sleep (REMS). Although reasonable progress has been made about neuro-physio-pharmacological mechanism of appearance of REMS, appearance of dreams is a mystery. Isolated studies have reported that substantia nigra (SN) withdraws inhibition from pedunculo-pontine tegmentum (PPT) acetylcholine (ACh)-ergic REM-ON neurons to trigger REMS; some REM-ON neurons become phasically active during REMS; amygdala (Amyg), a limbic structure associated with emotions, may be related with dreaming like state; Amyg receives projections from both SN-Dopamine (DA)-ergic and PPT-ACh-ergic neurons. Collating these isolated findings, we proposed that on the background of REMS, SN-DA-ergic and PPT-ACh-ergic inputs phasically activate Amyg-neurons to manifest dreams. In the absence of better criteria, we recorded electrophysiological characteristics of REMS as the closest objective read-out for dreams in surgically prepared, chronic, freely moving rats. Microinjection of either DA-ergic or ACh-ergic agonist [Quinpirole (Qnp) or Carbachol (Carb)] bilaterally into Amyg increased, while antagonists [Haloperidol (Hal) or Scopolamine (Scop)] reduced REMS. Electrical stimulation of either bilateral SN or PPT increased REMS, which however, was prevented when stimulated in presence of Hal or Scop, respectively into the Amyg. These findings confirm and support our contention that SN-DA-ergic and PPT-ACh-ergic inputs integrate in Amyg for REMS regulation. Further, subject to confirmation in humans, we propose that on the background of REMS, some phasic PPT-ACh-ergic-REM-ON neurons intermittently trigger some neurons in Amyg, the area known to be associated with memory and emotions, causing intermittent appearance of REMS-associated dreams and in REMS behavior disorder.

A Case Report of Wall-Eyed Bilateral Internuclear Ophthalmoplegia with Bilateral Facial Palsy.

Case reports of bilateral facial palsy with horizontal gaze restriction are rare. A 62-year-old woman experienced sudden onset of bilateral adduction deficits, bilateral abducting nystagmus accompanied with facial diplegia. We confirmed acute ischemic stroke in the midline dorsal pons, where medial longitudinal fasciculus (MLF) and facial nerve fascicles are located. This can be explained by vascular variation of pontine perforating arteries.

'Twenty syndrome' in neuromyelitis optica spectrum disorder.

A 30-year-old woman presented with recurrent hiccups, vomiting and painful diminution of vision and gait instability for 1 day. She had one-and-a-half syndrome, bilateral seventh cranial nerve paresis with bilateral symptomatic optic neuritis and left-sided ataxic haemiparesis. We described her disorder as the 'twenty syndrome' (11/2+7+7+2+2+½=20). MRI of her brain revealed demyelination predominantly in right posterolateral aspect of pons, medulla and bilateral optic nerves. Serum antiaquaporin-4 antibody came out positive. Thus, she was diagnosed as neuromyelitis optica spectrum disorder (NMOSD). She responded brilliantly to immunosuppressive therapy. This is the first ever reported case of the 'twenty syndrome' secondary to cerebral NMOSD.

A case report of pediatric neurotrophic keratopathy in pontine tegmental cap dysplasia treated with cenegermin eye drops.

RATIONALE: To report the management of recalcitrant neurotrophic keratopathy in a pediatric patient affected by pontine tegmental cap dysplasia (PTCD) using topical human recombinant nerve growth factor (hrNGF, Cenegermin 20 µg/ml). To the best of our knowledge the present case is one of the few described in patients with congenital NK treated with Cenegermin, and the first in a patient affected by PTCD. PATIENT CONCERNS: A 9-year-old patient, affected by PTCD with bilateral cranial nerve V1 and VIII palsies, was referred to our hospital for visual disturbances and redness of the right eye due to persistent neurotrophic epithelial defect. The patient presented marked developmental delay, ataxia, bilateral hypoacusia, and bilateral corneal severe hypoaesthesia. Ocular history revealed multiple treatments in order to treat neurotrophic ulcer in the left eye. Four years later, he developed a persistent epithelial defect with corneal anesthesia in the right eye. DIAGNOSES: The impaired trigeminal nerve function, due to the underlying congenital disease, led to the development of moderate NK (stage II) in the right eye and a mild NK (stage I) in the left eye. INTERVENTIONS: Cenegermin 20 µg/ml eye-drop was administered in both eyes. Treatment was continued for 8 weeks. The patient was assessed after 4 and 8 week of treatment. At each follow-up visit, treatment efficacy and adverse events were evaluated. OUTCOMES: The use of Cenegermin eye drops facilitated the remarkable resolution of the neurotrophic keratopathy and the improvement of corneal sensitivity in both eyes. No local or systemic adverse events were observed. LESSONS: Topical Cenegermin 20 µg/ml was well-tolerated and may represent a valuable therapeutic option in the management of pediatric neurotrophic keratopathy.

Neuronophagia and microglial nodules in a SARS-CoV-2 patient with cerebellar hemorrhage.

We document the neuropathologic findings of a 73-year old man who died from acute cerebellar hemorrhage in the context of relatively mild SARS-CoV2 infection. The patient developed sudden onset of headache, nausea, and vomiting, immediately followed by loss of consciousness on the day of admission. Emergency medical services found him severely hypoxemic at home, and the patient suffered a cardiac arrest during transport to the emergency department. The emergency team achieved return of spontaneous circulation after over 17 min of resuscitation. A chest radiograph revealed hazy bilateral opacities; and real-time-PCR for SARS-CoV-2 on the nasopharyngeal swab was positive. Computed tomography of the head showed a large right cerebellar hemorrhage, with tonsillar herniation and intraventricular hemorrhage. One day after presentation, he was transitioned to comfort care and died shortly after palliative extubation. Autopsy performed 3 h after death showed cerebellar hemorrhage and acute infarcts in the dorsal pons and medulla. Remarkably, there were microglial nodules and neuronophagia bilaterally in the inferior olives and multifocally in the cerebellar dentate nuclei. This constellation of findings has not been reported thus far in the context of SARS-CoV-2 infection.

Pontine A5 region modulation of the cardiorespiratory response evoked from the midbrain dorsolateral periaqueductal grey.

Connections between the midbrain dorsolateral periaqueductal grey (dlPAG) and the pontine A5 region have been shown. The stimulation of both regions evokes similar cardiovascular responses: tachycardia and hypertension. Accordingly, we have studied the interactions between dlPAG and A5 region in spontaneously breathing anesthetized rats. dlPAG was electrically stimulated (20-30 µA 1-ms pulses were given for 5 s at 100 Hz). Changes in the evoked cardiorespiratoy response were analysed before and after ipsilateral microinjections of muscimol (GABAergic agonist, 50 nl, 0.25 nmol, 5 s) within the A5 region. Electrical stimulation of the dlPAG produces, in the rat, a response characterized by tachypnoea (p < 0.001), hypertension (p < 0.001) and tachycardia (p < 0.001). The increase in respiratory rate was due to a decrease in expiratory time (p < 0.01). Pharmacological inhibition of the A5 region with muscimol produced a marked reduction of the tachycardia (p < 0.001) and the tachypnoea (p < 0.01) evoked from the dlPAG. Finally, to assess functional interactions between A5 and dlPAG, extracellular activity of putative A5 neurones were recorded during dlPAG electrical stimulation. Forty A5 cells were recorded, 16 of which were affected by dlPAG stimulation (40%). 4 cells showed activation, 5 cells excitation and 7 cells decreased spontaneous activity to dlPAG stimulation (p < 0.001). These results confirm a link between the A5 region and dlPAG. The potential role of these connections in the modulation of dlPAG evoked cardiorespiratory responses and their possible clinical implications are discussed.

Sex-specific alterations in GABA receptor-mediated responses in laterodorsal tegmentum are associated with prenatal exposure to nicotine.

Smoking during pregnancy is associated with deleterious physiological and cognitive effects on the offspring, which are likely due to nicotine-induced alteration in the development of neurotransmitter systems. Prenatal nicotine exposure (PNE) in rodents is associated with changes in behaviors controlled in part by the pontine laterodorsal tegmentum (LDT), and LDT excitatory signaling is altered in a sex and age-dependent manner by PNE. As effects on GABAergic LDT signaling are unknown, we used calcium imaging to evaluate GABAA receptor- (GABAA R as well as GABAA -ρ R) and GABAB receptor (GABAB R)-mediated calcium responses in LDT brain slices from female and male PNE mice in two different age groups. Overall, in older PNE females, changes in calcium induced by stimulation of GABAA R and GABAB R, including GABAA -ρ R were shifted toward calcium rises. In both young and old males, PNE was associated with alterations in calcium mediated by all three receptors; however, the GABAA R was the most affected. These results show for the first time that PNE is associated with alterations in GABAergic transmission in the LDT in a sex- and age-dependent manner, and these data are the first to show PNE-associated alterations in functionality of GABA receptors in any nucleus. PNE-associated alterations in LDT GABAergic transmission within the LDT would be expected to alter output to target regions and could play a role in LDT-implicated, negative behavioral outcomes following gestational exposure to smoking. Accordingly, our data provide further supportive evidence of the importance of eliminating the consumption of nicotine during pregnancy.

The brain of the African wild dog. III. The auditory system.

The large external pinnae and extensive vocal repertoire of the African wild dog (Lycaon pictus) has led to the assumption that the auditory system of this unique canid may be specialized. Here, using cytoarchitecture, myeloarchitecture, and a range of immunohistochemical stains, we describe the systems-level anatomy of the auditory system of the African wild dog. We observed the cochlear nuclear complex, superior olivary nuclear complex, lateral lemniscus, inferior colliculus, medial geniculate body, and auditory cortex all being in their expected locations, and exhibiting the standard subdivisions of this system. While located in the ectosylvian gyri, the auditory cortex includes several areas, resembling the parcellation observed in cats and ferrets, although not all of the auditory areas known from these species could be identified in the African wild dog. These observations suggest that, broadly speaking, the systems-level anatomy of the auditory system, and by extension the processing of auditory information, within the brain of the African wild dog closely resembles that observed in other carnivores. Our findings indicate that it is likely that the extraction of the semantic content of the vocalizations of African wild dogs, and the behaviors generated, occurs beyond the classically defined auditory system, in limbic or association neocortical regions involved in cognitive functions. Thus, to obtain a deeper understanding of how auditory stimuli are processed, and how communication is achieved, in the African wild dog compared to other canids, cortical regions beyond the primary sensory areas will need to be examined in detail.

Pontine Tegmentum Lesions Accompanying Myelitis During an Enterovirus Outbreak: Differential Diagnosis and Outcome.

AIM: To investigate etiology and prognostic significance of pontine tegmentum lesions accompanying a cluster of acute flaccid myelitis. METHOD: We retrospectively examined patients from 6 centers in Turkey who manifested encephalitis or myelitis associated with dorsal pontine lesions on magnetic resonance imaging (MRI) between July 2018 and February 2019. RESULTS: Twenty-two patients were evaluated. Ten of 22 (45%) presented with acute paralysis and 12 of 22 (55%) with brainstem symptoms only. Reverse transcription polymerase chain reaction for enterovirus was positive in 2 patients' respiratory tract. Other etiologic factors were detected in 10 cases. On follow-up, patients presenting with symptoms of myelitis developed motor sequalae although spinal cord lesions on MRI resolved in 5 of 9 (55%). Encephalitic symptoms, present in 17 cases, recovered in 13 (76%), and brain MRI showed complete or near-complete resolution in 11 of 14 (78%). CONCLUSION: Various etiologic agents can be detected in patients with pontine involvement, even in a series collected during an outbreak of EV-D68. Encephalitis has a fair outcome but clinical recovery is slow and motor sequalae are frequent in spinal involvement, irrespective of follow-up spinal MRI findings.

Afferents of the mouse linear nucleus.

The linear nucleus (Li) was identified in 1978 from its projections to the cerebellum. However, there is no systematic study of its connections with other areas of the central nervous system possibly due to the challenge of injecting retrograde tracers into this nucleus. The present study examines its afferents from some nuclei involved in motor and cardiovascular control with anterograde tracer injections. BDA injections into the central amygdaloid nucleus result in labeled fibers to the ipsilateral Li. Bilateral projections with an ipsilateral dominance were observed after injections in a) jointly the paralemniscal nucleus, the noradrenergic group 7/ Köllike -Fuse nucleus/subcoeruleus nucleus, b) the gigantocellular reticular nucleus, c) and the solitary nucleus/the parvicellular/intermediate reticular nucleus. Retrogradely labeled neurons were observed in Li after BDA injections into all these nuclei except the central amygdaloid and the paralemniscal nuclei. Our results suggest that Li is involved in a variety of physiological functions apart from motor and balance control it may exert via its cerebellar projections.

Wall-Eyed Bilateral Internuclear Ophthalmoplegia by Ischemic Stroke: Case Report and Literature Review.

INTRODUCTION: Wall-eyed bilateral internuclear ophthalmoplegia (WEBINO) is a rare symptom. Several studies have reported that a small brainstem lesion could cause WEBINO. CASE REPORT: The authors present the case of an 88-year-old female individual who developed sudden-onset diplopia and gait disturbance. Neurological examination revealed WEBINO with convergence impairment, gaze-evoked upward nystagmus on upward gaze, and bilateral limb ataxia. Brain magnetic resonance imaging revealed a small paramedian pontine tegmentum infarction, responsible for the symptoms. A literature review of WEBINO in ischemic stroke revealed that most patients exhibited impaired convergence and other neurological symptoms. CONCLUSION: Gaze-evoked upward nystagmus on upward gaze and bilateral limb ataxia accompanied by WEBINO due to a small brainstem lesion were the characteristic findings of our case.

Ocular Findings in Pontine Tegmental Cap Dysplasia.

PURPOSE: To describe the ocular complications experienced by patients with pontine tegmental cap dysplasia (PTCD) and the management strategies used to care for these children. METHODS: Subjects with PTCD were recruited through social media advertisement and completed a survey gathering information on potential ocular problems related to the patient's PTCD disease and any current or previous treatments. RESULTS: Twenty-two patients or guardians completed the survey. Neurotrophic cornea was the most common ocular diagnosis (82%), followed by facial palsy (59%), dry eye syndrome (59%), and blepharitis (55%). Other diagnoses included cortical visual impairment (27%), strabismus (27%), amblyopia (18%), and nystagmus (18%). Common treatment modalities included lubricating eye drops (59%) or ointment (50%), contact lenses (14%), punctal plugs (27%), glasses (45%), and patching (18%). The most common surgical interventions were temporary or permanent tarsorrhaphy (64%) and amniotic membrane grafts (23%). In total, 68% of families reported self-injury to eyes and 91% reported the child to be primarily a visual learner. CONCLUSIONS: PTCD is a newly described, very rare disorder with a variety of vision-threatening ocular manifestations. It is essential that the ophthalmologist be aware of the potential for neurotrophic cornea because timely treatment could prevent corneal scarring, perforation, and blindness.