Multiplexed and flexible neural coding in sensory, parietal, and frontal cortices during goal-directed virtual navigation

We do not understand how neural nodes operate within the recurrent action-perception loops that characterize naturalistic self-environment interactions, nor how brain networks reconfigure during changing computational demands. Here, we record local field potentials (LFPs) and spiking activity simultaneously from the dorsomedial superior temporal area (MSTd), parietal area 7a, and dorsolateral prefrontal cortex (dlPFC) as monkeys navigate in virtual reality to “catch fireflies”. This task requires animals to actively sample from a closed-loop visual environment while concurrently computing latent variables: the evolving distance and angle to a memorized firefly. We observed mixed selectivity in all areas, with even a traditionally sensory area (MSTd) tracking latent variables. Strikingly, global encoding profiles and unit-to-unit coupling suggested a functional subnetwork between MSTd and dlPFC, and not between these areas and 7a, as anatomy would suggest. When sensory evidence was rendered scarce, lateral connectivity through neuron-to-neuron coupling within MSTd strengthened but its pattern remained fixed, while neuronal coupling adaptively remapped within 7a and dlPFC. The larger the remapping in 7a/dlPFC and the greater the stability within MSTd, the less was behavior impacted by loss of sensory evidence. These results highlight the distributed nature of neural coding during closed-loop action-perception naturalistic behaviors and suggest internal models may be housed in the pattern of fine-grain lateral connectivity within parietal and frontal cortices.

Altered Topological Organization of Functional Brain Networks in Betel Quid Dependence: A Resting-State Functional MRI Study

Background: Betel quid dependence (BQD) is associated with abnormalities in the widespread inter-regional functional connectivity of the brain. However, no studies focused on the abnormalities in the topological organization of brain functional networks in chewers in Mainland China.Methods: In the current study, resting-state functional magnetic resonance images were acquired from 53 BQD individuals and 37 gender- and age-matched healthy controls (HCs). A functional network was constructed by calculating the Pearson correlation coefficients among 90 subregions in the human Brainnetome Atlas. The topological parameters were compared between BQD individuals and HCs.Results: The results showed that BQD individuals presented a small-world topology, but the normalized characteristic path length (λ) increased compared with HCs (0.563 ± 0.030 vs. 0.550 ± 0.027). Compared to HCs, BQ chewers showed increased betweenness centrality (Be) in the right supplementary motor area, right medial superior frontal gyrus, right paracentral lobule, right insula, left posterior cingulate gyrus, right hippocampus, right post-central gyrus, right superior parietal gyrus, and right supramarginal gyrus, while decreased Be was found in the orbitofrontal area and temporal area, which is associated with reward network, cognitive system, and default mode network. The area under the curve (AUC) value of λ displayed a positive correlation with the duration of BQ chewing (r = 0.410, p = 0.002).Conclusions: The present study revealed the disruption of functional connectome in brain areas of BQD individuals. The findings may improve our understanding of the neural mechanism of BQD from a brain functional network topological organization perspective.

КЛІНІЧНИЙ ВИПАДОК МОЖЛИВОЇ МІГРЕНІ З АУРОЮ, УСКЛАДНЕНОЇ МІГРЕНОЗНИМ ІНФАРКТОМ

We present a clinical case of ischemic stroke in a man with a new-onset migraine attack. Clinical case. A 25-year-old man was admitted to the acute cerebrovascular department due to severe throbbing headache in the left temporal area, vomiting, impaired vision on the right and numbness of the right leg. Complaints appeared abruptly in the form of scotoma in the right visual field. 20 minutes later, severe throbbing headache, nausea and numbness of the right leg developed. The event was preceded by sleep deprivation for 2 days. The patient’s mother has migraine with aura. Previously, the patient never had such attacks. On examination: right-sided homonymous upper-quadrant hemianopsia, hypoesthesia of the right leg. Brain MRI - focal hyperintensity at T2 and DWI in the left occipital region (acute ischemic stroke). The patient took aspirin at a dose of 300 mg for the first day, then 100 mg per day and valproic acid at a dose of 1200 mg per day. Two days after hospitalization, the patient experienced recovery of sensitivity in the right leg and regression of right-sided homonymous upper quadrant hemianopsia to small scotoma. The patient was discharged on the 5th day with a small right scotoma. It is recommended to continue taking aspirin 100 mg/day and valproic acid 1200 mg/day for the secondary prevention of migraine attacks and stroke. Discussion. The peculiarities of this case include the lack of history of migraine (at least 5 or more migrainous headache attacks) and the development of severe migraine attack with prolonged aura symptoms, which was triggered by sleep deprivation and eventually evolved into ischemic stroke. Conclusions. It is necessary to consider the possibility of ischemic stroke even in the cases of a new-onset migraine attack. If migrainous aura duration exceeds 60 minutes, it is necessary to perform a brain MRI to detect the early signs of cerebral ischemia.

Comparative Assessment of Silver Nanocomposites’ Biological Effects on the Natural and Synthetic Matrix

The aim of our investigation was to make a comparative assessment of the biological effects of silver nanoparticles encapsulated in a natural and synthetic polymer matrix. We carried out a comparative assessment of the biological effect of silver nanocomposites on natural (arabinogalactan) and synthetic (poly-1-vinyl-1,2,4-triazole) matrices. We used 144 three-month-old white outbred male rats, which were divided into six groups. Substances were administered orally for 9 days at a dose 500 μg/kg. Twelve rats from each group were withdrawn from the experiment immediately after nine days of exposure (early period), and the remaining 12 rats were withdrawn from the experiment 6 months after the end of the nine-day exposure (long-term period). We investigated the parietal–temporal area of the cerebral cortex using histological (morphological assessments of nervous tissue), electron microscopic (calculation of mitochondrial areas and assessment of the quality of the cell nucleus), and immunohistochemical methods (study of the expression of proteins regulating apoptosis bcl-2 and caspase 3). We found that the effect of the nanocomposite on the arabinogalactan matrix causes a disturbance in the nervous tissue structure, an increase in the area of mitochondria, a disturbance of the structure of nerve cells, and activation of the process of apoptosis.

Dementia with non-convulsive seizures: a case report

Non-convulsive seizures (NCSs) are highly treatable, but appropriate management is usually delayed because of inaccurate diagnoses as a result of variable clinical presentations, including an altered mental state. It is difficult to detect NCSs in patients with dementia. We report a case of NCS superimposed on cognitive decline caused by Alzheimer’s dementia. The patient’s history was carefully recorded. An electroencephalogram was recorded with sphenoidal electrodes, which showed epileptiform discharges in the right mesial temporal lobe and focal, sharply contoured, slow wave activity in the left fronto-temporal area, suggesting an epileptic origin contributing to the patient’s cognitive decline. After treatment with antiepileptic drugs, the patient’s cognitive functioning gradually improved. An accurate diagnosis of NCS relies on performing a detailed inventory of a patient’s history, thorough physical and neurological examinations, and electroencephalogram recordings. In patients with cognitive decline, testing for NCS should always be included in the differential diagnosis of cognitive impairment, even in the case of dementia. Early administration of antiepileptic drug therapy is the mainstay treatment for reversing the condition and for preventing prolonged insults from neurological sequelae.

Bioelectric activity of the brain in 3-4 years old children in eyes-open resting state

Background. Electroencephalography is the main technique for assessing the functional state of the brain. Indications for EEG are diagnosis of paroxysmal states, prediction of the outcome of a pathological state, evaluation of bioelectrical activity if brain death is suspected. Up to 90 % of the native EEG in calm wakefulness in healthy individuals is occupied by “alpha activity”. In children in active wakefulness, the EEG pattern depends to a great extent on their age.Objective. The aim of the work was to assess EEG parameters in children aged 3–4 years in eyes-open resting state. Design and methods. 31 healthy participants aged 3–4 years were enrolled. EEG was registered for 30 minutes in a state of passive wakefulness in the supine position with open eyes. Average values of the power of the spectra for the alpha-rhythm, delta-rhythm and theta-rhythm in the frontal and temporal leads, as well as the ratio of the average power of alpha/theta and alpha/delta rhythms in the frontal and temporal leads were calculated.Results. Average power of the alpha-rhythm was significantly higher over the right frontal lobe than over the right frontal-temporal area, as well as average amplitude of it was significantly higher in F3-A1 than F7-A1, F4-A2 than F8-A2, which is associated with the articulatory praxis. Average alpha-rhythm power was significantly higher in T5-A1 than T3-A1 and T6-A2 than T4-A2, which corresponds to the recognition and naming of objects optically. Significant differences according to the total average power of the alpha- and theta-rhythms above the frontal and frontal-temporal regions reflect the relationship between the frontal cortex temporal lobes and the premotor zones, i.e. arcuate bundle, responsible for the “speech system”.Conclusion. The identified patterns can reflect the characteristics of the state of active wakefulness in a 3–4-year-old child and can be used for comparison in the future (both in the course of behavioral experiments and observation of patients with certain pathological processes).

EEG Contribution to the Diagnosis of Antibody-Negative Autoimmune Encephalitis: A Case Report

Autoimmune encephalitis (AE) is a group of inflammatory brain diseases that are characterized by prominent neuropsychiatric symptoms. Early therapeutic intervention is important for AE. Therefore, without waiting for autoantibody test results, clinicians must consider the possibility of AE based solely on clinical symptoms and conventional test results. The case described herein is of antibody-negative encephalitis with abnormalities shown only by EEG, which contributed to the diagnosis and treatment. The patient, a 20-year-old woman, showed autonomic seizures in addition to movement disorders, psychiatric symptoms, and cognitive dysfunction, which worsened subacutely. Her seizures and movement disorders were not responsive to antiepileptic medications. Results obtained from MRI and cerebrospinal fluid (CSF) were normal; EEG findings showed repeated spikes in the right temporal area, with changes over time. Based on the clinical course and EEG, along with administered immunotherapy, which resolved seizures, movement disorders, and psychiatric symptoms, we suspected AE. For diagnosis of AE and for evaluating treatment responsiveness, EEG was useful. Results indicate that EEG can assist clinicians even with AE cases for which MRI and CSF findings are normal.

Sex differences in behavioural and anatomical estimates of visual acuity in the green swordtail Xiphophorus helleri

Among fishes in the family Poeciliidae, signals such as colour patterns, ornaments, and courtship displays play important roles in mate choice and male-male competition. Despite this, visual capabilities in Poeciliids are understudied, in particular visual acuity, the ability to resolve detail. We used three methods to quantify visual acuity in male and female green swordtails (Xiphophorus helleri), a species in which body size and the length of the male's extended caudal fin (‘sword’) serve as assessment signals during mate choice and agonistic encounters. Topographic distribution of retinal ganglion cells (RGC) was similar in all individuals and characterized by areas of high cell densities located centro-temporally and nasally, as well as a weak horizontal streak. Based on the peak density of RGC in the centro-temporal area, anatomical acuity was estimated to be approximately 3 cycles/degree (cpd) in both sexes. However, a behavioural optomotor assay found significantly lower mean acuity in males (0.8 cpd) than females (3.0 cpd), which was not explained by differences in eye size between males and females. An additional behavioural assay, in which we trained individuals to discriminate striped gratings from grey stimuli of the same mean luminance, also showed lower acuity in males (1-2 cpd) than females (2-3 cpd). Thus, although retinal anatomy predicts identical acuity in males and females, two behavioural assays found higher acuity in females than males, a sexual dimorphism which is rare outside of invertebrates. Overall, our results have implications for understanding how Poeciliids perceive visual signals during mate choice and agonistic encounters.

Choroidal Volume Evaluation after Photodynamic Therapy Using New Optical Coherence Tomography Imaging Algorithm

To evaluate choroidal volume and thickness changes after photodynamic therapy (PDT) for chronic central serous chorioretinopathy (CSC). Chronic CSC eyes with a history of PDT were selected. Average choroidal volume, average choroidal thickness, the maximum and minimum choroidal thickness of the macula irradiated area and peripheral non-irradiated areas before and after one and three months of treatment were examined. A total of 14 patients with chronic CSC and 9 controls without any eye pathology were enrolled. The mean choroidal volume in CSC before and, and after one and three months of treatment were 2.36 (standard deviation: 0.70), 1.90 (0.69), 1.86 (0.66) mm3 for the central area, 1.25 (0.38), 1.14 (0.35), 1.13 (0.34) mm3 for superior nasal area, 1.47 (0.41), 1.28 (0.43), 1.26 (0.43) mm3 for superior temporal area, 1.07 (0.49), 0.95 (0.38), 0.93 (0.35) mm3 for inferior nasal area, 1.17 (0.38), 1.04 (0.32), 1.03 (0.33) mm3 for inferior temporal area. This study revealed the choroidal volume changes in a short period after PDT and a decrease in unirradiated choroidal volume was also shown after the treatment. The algorithm provided on the ARI Network enables to evaluate the choroidal changes quantitatively and qualitatively.

The Relationship Between Emotional Content and Phonological Processing in Persian Speaking Children Who Stutter: A Study by Event-related Potential

Introduction: Emotion can contribute to the severity of stuttering, although the underlying mechanism is unknown. Event-related Potential (ERP) could be very helpful for assessing emotional processing in persons with stuttering. Our study aimed at the investigation of phonological processing for emotional and neutral words in Children Who Stutter (CWS) by ERP. Materials and Methods: Ten CWS were given 120 emotional and neutral words to read. Phonological processing was assessed by aloud reading task, while simultaneously ERP was recorded. The results were analyzed as behavioral (reaction time and accuracy) and electrophysiological (amplitude and topography). Results: There were significant differences in reaction time and accuracy between positive, negative, and neutral words (P<0.05). The electrophysiological data analysis showed significant differences for a minimum of amplitude in the left frontal area, for a maximum of amplitude in the right temporal area, and peak to peak distance in the left frontal area (P<0.05). Visual inspection suggested that recorded fluctuations have a bigger amplitude range for neutral words in all brain regions, except prefrontal, frontal and right frontal. Conclusion: Valence would affect behavioral measures. Generally, emotion facilitates word processing by reducing activity in anterior brain areas in phonological processing time.