Activity in the pontine reticular nuclei scales with handgrip force in humans.

The neural pathways that contribute to force production in humans are currently poorly understood, as the relative roles of the corticospinal tract and brainstem pathways, such as the reticulospinal tract (RST), vary substantially across species. Using functional magnetic resonance imaging (fMRI), we aimed to measure activation in the pontine reticular nuclei (PRN) during different submaximal handgrip contractions to determine the potential role of the PRN in force modulation. Thirteen neurologically intact participants (age: 28 ± 6 yr) performed unilateral handgrip contractions at 25%, 50%, 75% of maximum voluntary contraction during brain scans. We quantified the magnitude of PRN activation from the contralateral and ipsilateral sides during each of the three contraction intensities. A repeated-measures ANOVA demonstrated a significant main effect of force (P = 0.012, [Formula: see text] = 0.307) for PRN activation, independent of side (i.e., activation increased with force for both contralateral and ipsilateral nuclei). Further analyses of these data involved calculating the linear slope between the magnitude of activation and handgrip force for each region of interest (ROI) at the individual-level. One-sample t tests on the slopes revealed significant group-level scaling for the PRN bilaterally, but only the ipsilateral PRN remained significant after correcting for multiple comparisons. We show evidence of task-dependent activation in the PRN that was positively related to handgrip force. These data build on a growing body of literature that highlights the RST as a functionally relevant motor pathway for force modulation in humans.NEW & NOTEWORTHY In this study, we used a task-based functional magnetic resonance imaging (fMRI) paradigm to show that activity in the pontine reticular nuclei scales linearly with increasing force during a handgrip task. These findings directly support recently proposed hypotheses that the reticulospinal tract may play an important role in modulating force production in humans.

A spatially-resolved transcriptional atlas of the murine dorsal pons at single-cell resolution.

The "dorsal pons", or "dorsal pontine tegmentum" (dPnTg), is part of the brainstem. It is a complex, densely packed region whose nuclei are involved in regulating many vital functions. Notable among them are the parabrachial nucleus, the Kölliker Fuse, the Barrington nucleus, the locus coeruleus, and the dorsal, laterodorsal, and ventral tegmental nuclei. In this study, we applied single-nucleus RNA-seq (snRNA-seq) to resolve neuronal subtypes based on their unique transcriptional profiles and then used multiplexed error robust fluorescence in situ hybridization (MERFISH) to map them spatially. We sampled ~1 million cells across the dPnTg and defined the spatial distribution of over 120 neuronal subtypes. Our analysis identified an unpredicted high transcriptional diversity in this region and pinpointed the unique marker genes of many neuronal subtypes. We also demonstrated that many neuronal subtypes are transcriptionally similar between humans and mice, enhancing this study's translational value. Finally, we developed a freely accessible, GPU and CPU-powered dashboard ( http://harvard.heavy.ai:6273/ ) that combines interactive visual analytics and hardware-accelerated SQL into a data science framework to allow the scientific community to query and gain insights into the data.

Pontine tegmental cap dysplasia: the role of diffusion tensor imaging.

Pontine tegmental cap dysplasia (PTCD) is a rare hindbrain malformation syndrome. Recurrent aspiration pneumonia is a major cause of death during a first year of life. We report the case of month-old child with an inability to suck milk since birth and multiple convulsions. PTCD was identified using tractography and MRI. This case report describes the imaging findings, the role of diffusion tensor imaging in PTCD and its differentiating features from Joubert syndrome and related disorders (JSRDs). The constellation of imaging features in PTCD includes a midbrain appearance resembling a molar tooth, a flattened anterior pontine belly, hypoplastic middle cerebellar peduncles and dorsal pontine tegmental cap. 'Tegmental cap' is a transversely oriented abnormal bundle of fibres with absent superior cerebellar peduncle decussation. Accurate diagnosis with MRI and tractography and differentiating PTCD from JSRD would help the clinician for appropriate genetic counselling and prognosis.

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.

Central tegmental tract hyperintensity: follow-up outcomes from a single-center study.

PURPOSE: To evaluate the follow-up outcomes of symmetrical central tegmental tract hyperintensity (CTTH) and discuss possible etiological factors involved. METHODS: Brain MRI scans of 7028 pediatric patients aged 0 to 18 years obtained between July 2015 and May 2020, were reviewed retrospectively for the presence of CTTH. Clinical data of the patients were retrieved from the hospital information system. Patients with follow-up MRI scans were evaluated separately. RESULTS: A total of 5113 patients meeting the study inclusion criteria were identified in whom the prevalence of CTTH was 4.02% (n = 206). Of the patients with CTTH, 40.3% (n = 83) were girls, and the median age was 19 months (range, 1-108). The most common MRI indication was seizures (40.3%, n = 83), and among those with a definitive diagnosis, epilepsy was the most prevalent etiology (7.8%, n = 16). 40.7% (n = 84) of the patients with CTTH had follow-up MRI scans. CTTH disappeared on follow-up in 28.6% (n = 24) of the patients. The median age at CTTH disappearance was 51.5 months, and the mean (± SD) time to CTTH disappearance was 31.50 (± 19.02) months. CONCLUSION: CTTH is a radiological finding commonly seen in early childhood but its clinical relevance has not been fully elucidated. While CTTH may be a transient phenomenon representing the maturation process, it may also be associated with a number of clinical conditions. Using a large patient series and follow-up MRI scans, our study shed light on the possible etiological factors of CTTH and its evolution over time.

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.

Clinicopathological features of progressive supranuclear palsy with asymmetrical atrophy of the superior cerebellar peduncle.

Progressive supranuclear palsy (PSP) can be diagnosed despite the presence of asymmetrical parkinsonism depending on the clinical diagnostic criteria. Some studies have reported that atrophy of the superior cerebellar peduncle (SCP) is more frequent in PSP than in Parkinson's disease. There have also been reports of PSP cases with an asymmetrically atrophic SCP. Therefore, we analyzed 48 specimens from consecutive autopsy cases that were neuropathologically diagnosed as PSP to investigate the laterality of brain lesions, including the SCP. We measured the width of the SCP and evaluated the laterality of atrophy. We semi-quantitatively evaluated neuronal loss, atrophy/myelin pallor, and tau pathology in three steps. Asymmetrical atrophy of the SCP was present in seven (14.6%) of 48 cases. The atrophic side of the SCP corresponded to the dominant side of the tau pathology in the cerebellar dentate nucleus. It was opposite to the dominant side of the myelin pallor and tau pathology in the red nucleus and of the tau pathology in the central tegmental tract and inferior olivary nucleus, coinciding with the neurologically systematic anatomy of the Guillain-Mollaret triangle. Neurodegeneration of PSP can progress asymmetrically from one side to the initially intact side in PSP with an initial predominance of Richardson's syndrome, progressive gait freezing, ocular motor dysfunction, parkinsonism, or corticobasal syndrome. To our knowledge, no previous study has reported asymmetrical PSP neuropathology; this is the first study to report the presence of PSP cases with asymmetrical SCP atrophy and systematically asymmetrical degeneration of the Guillain-Mollaret triangle.

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 (MPLSST neurons) in mice promote self-grooming and encode reward. MPLSST neurons display prominent grooming-related neuronal activity. Loss of function of MPLSST neurons impairs both self-grooming and post-stress anxiety alleviation. Activation of MPLSST 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 MPLSST neurons. MPLSST neuron-mediated self-grooming is triggered by the input from the central amygdala (CeA). Our study reveals a dual role of CeA-MPLSST-VTADA circuit in self-grooming and post-stress anxiety regulation and conceptualizes MPLSST 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.

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.

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.

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.