Volume of Amygdala Subregions and Clinical Manifestations in Patients With First-Episode, Drug-Naïve Major Depression

We examined amygdala subregion volumes in patients with a first episode of major depression (MD) and in healthy subjects. Covariate-adjusted linear regression was performed to compare the MD and healthy groups, and adjustments for age, gender, and total estimated intracranial volume showed no differences in amygdala subregion volumes between the healthy and MD groups. Within the MD group, we examined the association between amygdala subregion volume and the 17-item Hamilton Rating Scale for Depression (HAMD) score and the HAMD subscale score, and found no association in the left amygdala. In the right amygdala, however, there was an inverse linear association between the HAMD total and the HAMD core and lateral nucleus and anterior-amygdaloid-regions. Furthermore, an inverse linear association was seen between the HAMD psychic and the lateral nucleus, anterior-amygdaloid-regions, transition, and whole amygdala. The findings of this study suggest that the severity of MD and some symptoms of MD are associated with right amygdala volume. There have been few reports on the relationship between MD and amygdala subregional volume, and further research is needed to accumulate more data for further validation.

Study on the pathogenesis of Holmes tremor by multimodal 3D medical imaging: case reports of three patients

Background We examined for the first time the imaging characteristics of Holmes tremor (HT) through multimodal 3D medical imaging. Case presentation Three patients with Holmes tremor who visited the Affiliated Hospital of Chengdu University of TCM from August 2018 to April 2021 were retrospectively investigated to summarize their clinical and imaging data. Results Holmes tremor in two of the three patients was caused by hypertensive cerebral hemorrhage and in the third patient induced by hemorrhage due to ruptured brain arteriovenous malformations. HT occurred 1 to 24 months after the primary disease onset and manifested as a tremor in the contralateral limb, mostly in the upper portion. Cranial MRI showed that the lesions involved the thalamus in all three patients. The damaged thalamic nuclei included the ventral anterior nucleus, ventral lateral nucleus and ventromedial lateral nucleus, and the damaged nerve fibers included left thalamocortical tracts in one patient. In the other two patients, the damaged thalamic nuclei included the centromedian and dorsomedial nucleus, and the damaged nerve fibers included left cerebellothalamic and thalamocortical tracts. One patient showed significant improvement after treatment with pramipexole while the other two patients exhibited a poor response, one of whom had no response to the treatment with pramipexole and was only significantly relieved by clonazepam. Conclusion We used multimodal 3D medical imaging for the first time to analyze the pathogenesis of HT and found that multiple thalamic nuclei were damaged. The damaged nuclei and nerve fiber tracts of two patients were different from those of the third patient, with different clinical manifestations and therapeutic effects. Therefore, it is speculated that there may be multiple pathogeneses for HT.

Thalamostriatal System Controls the Acquisition, Performance, and Flexibility of Learning Behavior

The dorsal striatum (DS) is a key structure of the basal ganglia circuitry, which regulates various types of learning processes and flexible switching of behavior. Intralaminar thalamic nuclei (ILNs) provide the main source of thalamostriatal inputs to the DS and constitute multiple nuclear groups, each of which innervates specific subdivisions of the striatum. Although the anatomical and electrophysiological properties of thalamostriatal neurons have been previously characterized, the behavioral and physiological functions of these neurons remain unclarified. Two representative thalamostriatal cell groups in the parafascicular nucleus (PF) and the central lateral nucleus (CL) are located in the caudal and rostral regions of the ILNs in rodents. Recently, the behavioral roles of these thalamostriatal cell groups have been investigated by the use of genetic and pharmacological manipulation techniques. In the current review, we summarize behavioral studies on thalamostriatal neurons, showing the key roles of these neurons in different learning processes, such as the acquisition, performance, and flexibility of behavior.

Distinct fastigial output channels and their impact on temporal lobe seizures

Despite being canonically considered a motor control structure, the cerebellum is increasingly recognized for important roles in processes beyond this traditional framework, including seizure suppression. Excitatory fastigial neurons project to a large number of downstream targets, and it is unclear if this broad targeting underlies seizure suppression, or if a specific output may be sufficient. To address this question, we used the intrahippocampal kainic acid mouse model of temporal lobe epilepsy, male and female animals, and a dual-virus approach to selectively label and manipulate fastigial outputs. We examined fastigial neurons projecting to the superior colliculus, medullary reticular formation, and central lateral nucleus of the thalamus, and found that these comprise largely non-overlapping populations of neurons which send collaterals to unique sets of additional thalamic and brainstem regions, creating distinct, somewhat overlapping, output channels. We found that neither optogenetic stimulation of superior colliculus nor reticular formation output channels attenuated hippocampal seizures. In contrast, on-demand stimulation of fastigial neurons targeting the central lateral nucleus robustly inhibited seizures. Our results indicate that fastigial control of hippocampal seizures does not require simultaneous modulation of many fastigial output channels. Rather, selective modulation of the fastigial output channel to the central lateral thalamus, specifically, is sufficient for seizure control. This may provide a means for more selective therapeutic interventions, which provide seizure control while minimizing unwanted side effects. More broadly, our data highlight the concept of specific cerebellar output channels, whereby discrete cerebellar nucleus neurons project to specific aggregates of downstream targets, with distinct functional outcomes.

Progressive lacunar stroke presenting as cheiro-oral syndrome, dysarthria and hemiataxia

Context: Lacunar infarcts are small infarcts caused by occlusion of a single penetrating vessel, affecting mostly the basal ganglia, subcortical white matter and pons1. Around 20-30% of patients may progress symptoms over hours to days, and this presentation is associated with disability and poor prognosis2. Case report: A 70-year-old man with history of smoking, hypertension and a previous right occipital stroke reported right upper lip paresthesias since awakening. In 2-hours the right perioral region and his right hand were affected. After 3-hours he noted slurred speech. After 4-hours, imbalance was added to the previous symptoms. On admission, NIHSS was 4, mostly by previous left hemianopia, new right arm ataxia and cerebellar dysarthria. There were no weakness or sensory déficits. Brain MRI showed a subacute lacunar stroke in the left thalamus. Discussion: Thalamic lacunar strokes can present in a wide range of symptoms depending on the affected nuclei. The ventral posterior lateral nucleus (VPLn) and the ventral posterior medial nucleus (VPMn) carries sensory input from the contralateral body and face, respectively3. Cheiro-oral syndrome (COS) is considered a pure sensory thalamic lacunar syndrome with symptoms that affect the face, hand and/or foot, but may be accompanied by ipsilateral ataxia if the ventral lateral nucleus is also affected4 . Although classically associated with thalamic ischemic lesions, there are descriptions of hemorrhagic strokes5 and multiple different affected regions presenting as COS, including brainstem5 , internal capsule6 , operculum7 , cortex8 , corona radiata9 and thalamus10. Early recognition and diagnosis is essencial to institute adequate early treatment and secondary prophylaxis.

Neuroarchitectonics of the medulla oblongata of cattle

The article presents data from the study of neuroarchitectonics of the medulla oblongata of cattle. The main attention was paid to the peculiarities of neuronal morphology, determination of their type and prevalence of a certain population of cells in the tissue. The study was performed on 23 brain samples taken from animals aged 2–11 years. To reveal the architectonics of neurons, methods of fabric impregnation with silver were used according to Golgi, Ramon-Kahal and Bolshovsky. The main criteria for determining the type of cells were such features as: cell body size, its shape, number and distribution of processes, their thickness, tortuosity and branching. According to the results, we can identify four main populations of neurons, which are represented by such morphofunctional cell types as: reticular, large polygonal (motor), small round (sensory) and spindle-shaped. The largest population consists of reticular neurons, the second most common are sensory, then motor and the least represented spindle-shaped. It was found that the population of sensory-type neurons includes such structures as the Gracilis and Cutaneus nucleus, the complex of olive inferior nuclei and the nucleus of the solitary tract. Motor are represented respectively in the dorsal, ventral and lateral motor nuclei, the hipoglossy nucleus, the ventral nucleus of the vagus nerve and the ventral subunit of the dorsal nucleus of the vagus nerve. Spindle-shaped neurons are represented only in the dorsal subunit of the dorsal nucleus of the vagus nerve, and reticular form the largest population represented by the reticular formation and the lateral nucleus. A certain pattern of distribution of cell types in the tissue is traced. Thus, the most archaic and architectural – reticular neurons form the center of cell mass, while specialized forms of cells – motor and sensory distributed on the periphery. In a separate type, spindle-shaped neurons of the dorsal nucleus of the vagus nerve are isolated, as cells of the transition link from reticular to motor.

Midbrain and lateral nucleus accumbens dopamine depletion affects free-choice high-fat high-sugar diet preference in male rats

ABSTRACTDopamine influences food intake behavior. Reciprocally, food intake, especially of palatable dietary items, can modulate dopamine-related brain circuitries. Among these reciprocal impacts, it has been observed that an increased intake of dietary fat results in blunted dopamine signaling and, to compensate this lowered dopamine function, caloric intake may subsequently increase. To determine how dopamine regulates food preference we did 6-hydroxydopamine (6-OHDA) lesions, depleting dopamine in specific brain regions in male Sprague Dawley rats. The food preference was assessed by providing the rats with free choice access to control diet, fat, 20% sucrose and tap water. Rats with midbrain lesions targeting the substantia nigra (which is also a model of Parkinson’s disease) consumed fewer calories, as reflected by a decrease in control diet intake, but they surprisingly displayed an increase in fat intake, without change in the sucrose solution intake compared to sham animals. To determine which of the midbrain dopamine projections may contribute to this effect, we next compared the impact of 6-OHDA lesions of terminal fields, targeting the dorsal striatum, the lateral nucleus accumbens and the medial nucleus accumbens. We found that 6-OHDA lesion of the lateral nucleus accumbens, but not of the dorsal striatum or the medial nucleus accumbens, led to increased fat intake. These findings indicate a role for lateral nucleus accumbens dopamine in regulating food preference, in particularly the intake of fat.HIGHLIGHTSDopamine influences fat intakeAnimal model of Parkinson’s disease display lower kcal intake but increased fat choiceDopamine depletion in the lateral nucleus accumbens favors fat intake

Non-thalamic origin of zebrafish sensory nuclei implies convergent evolution of visual pathways in amniotes and teleosts

Ascending visual projections similar to the mammalian thalamocortical pathway are found in a wide range of vertebrate species, but their homology is debated. To get better insights into their evolutionary origin, we examined the developmental origin of a thalamic-like sensory structure of teleosts, the preglomerular complex (PG), focusing on the visual projection neurons. Similarly to the tectofugal thalamic nuclei in amniotes, the lateral nucleus of PG receives tectal information and projects to the pallium. However, our cell lineage study in zebrafish reveals that the majority of PG cells are derived from the midbrain, unlike the amniote thalamus. We also demonstrate that the PG projection neurons develop gradually until late juvenile stages. Our data suggest that teleost PG, as a whole, is not homologous to the amniote thalamus. Thus, the thalamocortical-like projections evolved from a non-forebrain cell population, which indicates a surprising degree of variation in the vertebrate sensory systems.