Olfactory Areas Research Articles

The Relationship between Plasma Hypocretin Levels and Sleep Disorders in Patients with Parkinson's Disease

Introduction: There are many areas of brain degeneration in people with Parkinson's disease. The dopaminergic degeneration process in the midbrain causes early symptoms of sleep disturbances. Hypocretin produced by the hypothalamus is involved in the pathophysiology of Parkinson's disease. Some research results regarding the relationship between plasma hypocretin levels and sleep disorders in patients with Parkinson's disease are still controversial.
 Method: This research is a cross sectional study in Neurology Polyclinic Dr. M. Djamil Padang and Network Hospital. All research subjects measured hypocretin levels and sleep disorders using the Epworth Sleepiness Scale. Statistical analysis was performed on a computerized basis using IBM SPSS statistics version 23.0 for windows.
 Result: A total of 60 patients with Parkinson's disease were included in this study, 30 subjects experienced sleep disorders and 30 others had no sleep disorders. There was a significant difference in lower plasma hypocretin levels in the Parkinson's group with sleep disorders, namely 81.817 ± 22.770 and in the group without sleep disorders, plasma hypocretin levels were found to be 255.416 ± 226.590 (p = 0.000). There was no statistical difference in clinical degree, age, duration of illness between the Parkinson's group with sleep disorders and the group without sleep disorders p > 0.05.
 Conclusion: There is a significant difference in hypocretin levels against the sleep disorder group in people with Parkinson's disease. In this study, there was no association between age, clinical degree of Parkinson's disease, and duration of Parkinson's disease and sleep disturbances. Degeneration in the olfactory bulb area, hypothalamus, and brainstem can precede dopaminergic degeneration in the midbrain and cause sleep disturbance symptoms.

State of the art olfactometers. Different types

The complexity of human olfaction is very high and the importance of being able to measure it directly, objectively and qualitatively has led experts to search for mechanisms that can be applied. Human beings use this sense, which is one of the oldest, to recognize danger and distinguish between pleasant and unpleasant odors. Smells are mixtures of molecules that, at different concentrations in the inhaled air, stimulate the olfactory area and are recognized at the brain level. Therefore, there is a coding and decoding system. Human olfactometer techniques use equipment designed to be able to measure its intensity and quality of volatile substances. If we are able to measure this sense, we will be able to know its variations and be able to make clinical diagnoses in normal and pathological conditions and diagnose the losses that occur in certain infectious, degenerative diseases, traumatic processes and other variants. For many years, systems have been developed that can measure subjective olfaction in humans, as well as objective forms, but it is also true that there is no equipment available that is fast, simple handling and that can be applied in daily clinical services. Aim of the Study Present the recent achievements in olfactometer technology; Elaborate the scientific articles about olfactometry published mainly in the last 10 years; To gather the information published in the last years in relation to the usefulness, existence in the market and purposes of equipment that can measure the odors, what we will call the Smell-o-meter or olfactometer for human use. Material and Methods: In the first part of this research we will gather most of the information existing so far in international bibliography, as well as the achievements and utilities obtained to date. Following, we will analyze all the new concepts related to smell-o-meters devices that exist on the market and assess the possibility, based on what has been done so far, to seek new practical systems for application in the medical field.

Reorganizing brain structure through olfactory training in post-traumatic smell impairment: An MRI study

Purpose and backgroundPost-traumatic olfactory dysfunction (PTOD), mostly caused by head injury, is thought to be associated with changes in the structure and function of the brain olfactory processing areas. Training and repeated exposure to odorants lead to enhanced olfactory capability. This study investigated the effects of a 16-weeks olfactory training (OT) on olfactory function and brain structure. MethodsTwenty-five patients with PTOD were randomly divided in three groups: (1) 9 control patients who did not receive any training, (2) 9 patients underwent classical OT by 4 fixed odors, and (3) 7 patients underwent modified OT coming across 4 sets of 4 different odors sequentially. Before and after the training period, all patients performed olfactory function tests and structural magnetic resonance imaging (MRI). Sniffin’ Sticks test was used to assess olfactory function. MRI data were analyzed using voxel-based morphometry and surface-based morphometry. ResultsBoth trained groups showed a considerable recovery of olfactory function, especially in odor identification. MRI data analysis revealed that the classical OT leads to increases in cortical thickness/density of several brain regions, including the right superior and middle frontal gyrus, and bilateral cerebellums. In addition, the modified OT yielded a lower extent of cortical measures in the right orbital frontal cortex and right insular. Following modified OT, a positive correlation was observed between the odor identification and the right orbital frontal cortex. ConclusionBoth olfactory training methods can improve olfactory function and that the improvement is associated with changes in the structure of olfactory processing areas of the brain.

Global Neurotoxicity: Quantitative Analysis of Rat Brain Toxicity Following Exposure to Trimethyltin.

The organotin, trimethyltin (TMT), is a highly toxic compound. In this study, silver-stained rat brain sections were qualitatively and quantitatively evaluated for degeneration after systemic treatment with TMT. Degenerated neurons were counted using image analysis methods available in the HALO image analysis software. Specific brain areas including the cortex, inferior and superior colliculus, and thalamus were quantitatively analyzed. Our results indicate extensive and widespread damage to the rat brain after systemic administration of TMT. Qualitative results suggest severe TMT-induced toxicity 3 and 7 days after the administration of TMT. Trimethyltin toxicity was greatest in the hippocampus, olfactory area, cerebellum, pons, mammillary nucleus, inferior and superior colliculus, hypoglossal nucleus, thalamus, and cerebellar Purkinje cells. Quantification showed that the optic layer of the superior colliculus exhibited significantly more degeneration compared to layers above and below. The inferior colliculus showed greater degeneration in the dorsal area relative to the central area. Similarly, in cortical layers, there was greater neurodegeneration in deeper layers compared to superficial layers. Quantification of damage in various thalamic nuclei showed that the greatest degeneration occurred in midline and intralaminar nuclei. These results suggest selective neuronal network vulnerability to TMT-related toxicity in the rat brain.

Whole-Brain Mapping the Direct Inputs of Dorsal and Ventral CA1 Projection Neurons.

The CA1, an important subregion of the hippocampus, is anatomically and functionally heterogeneous in the dorsal and ventral hippocampus. Here, to dissect the distinctions between the dorsal (dCA1) and ventral CA1 (vCA1) in anatomical connections, we systematically analyzed the direct inputs to dCA1 and vCA1 projection neurons (PNs) with the rabies virus-mediated retrograde trans-monosynaptic tracing system in Thy1-Cre mice. Our mapping results revealed that the input proportions and distributions of dCA1 and vCA1 PNs varied significantly. Inside the hippocampal region, dCA1 and vCA1 PNs shared the same upstream brain regions, but with distinctive distribution patterns along the rostrocaudal axis. The intrahippocampal inputs to the dCA1 and vCA1 exhibited opposite trends, decreasing and increasing gradually along the dorsoventral axis, respectively. For extrahippocampal inputs, dCA1 and vCA1 shared some monosynaptic projections from certain regions such as pallidum, striatum, hypothalamus, and thalamus. However, vCA1, not dCA1, received innervations from the subregions of olfactory areas and amygdala nuclei. Characterization of the direct input networks of dCA1 and vCA1 PNs may provide a structural basis to understand the differential functions of dCA1 and vCA1.

Meningocele in the olfactory area in spontaneous CSF rhinorrhea

Introduction: Spontaneous leakage of cerebrospinal fluid from the nasal cavity due to a defect in the anterior, middle and posterior skull base is a condition associated with both difficult clinical diagnosis and challenges in preoperative localization and treatment. Material and methods: For a period of 19 years in the Clinic of Ear, Nose and Throat at the University Hospital “St. George” were diagnosed 11 cases of spontaneous rhinorrhea with the presence of meningocele in the area of the olfactory cleft Results: In 8 of the clinical cases, we administered intrathecal fluorescein 10% due to the inconclusive data from HRCT and MRI / Cisternography for bone and dural defect in the base area in a positive beta 2 transferrin test. We find that the olfactory cleft is common localization in spontaneous CSF rhinorrhea. Conclusion: The elective choice of diagnostic method with aimed examination for defectarachnoid dilatation in the area of lamina cribrosa, meningocele in the area of the olfactory cleft and those in the sphenoid sinus significantly improves the quality of surgical treatment (preservation of the olfactory area on one side, minimizing orbital and additional dural defects). The discussion in multidisciplinary teams provides significant opportunities for accurate and timely diagnosis of this type of “hidden” defects. ------------------------------------------------------------------------------ Въведение: Спонтанното изтичане на ликвор от носната кухина вследствие на дефект в областта на предна, средна и задна база на черепа е състояние, свързано както със затруднено клинично диагностициране, така и с предизвикателства в предоперативното локализиране и лечение. Материал и методи: За период от 19 години в Клиниката по уши нос и гърло в УМБАЛ „Свети Георги“ са диагностицирани 11 случаи на спонтанна риноликворея с наличие на менингоцеле в областта на олфакторната цепка. Резултати: При 8 от клиничните случаи сме приложили интратекално флуоресцеин 10% поради неубедителните данни от HRCT и МРТ/ цистернография за костен и дурален дефект в областта на базата при позитивен бета 2 трансферинов тест. Установяваме, че олфакторната зона е най-честата локализация при спонтанна риноликворея. Заключение: Елективният избор на метод за диагностика с насочено търсене на дефект-арахноидна дилатация в областта на ламина криброза, менингоцеле в областта на олфактоната цепка, както и такива в сфеноидалния синус значително подобрява качеството в оперативното лечение (запазване на олфакторна зона от едната страна, минимизиране орбитални и допълнителни дурални дефекти). Съвместното дискутиране в мултидисциплинарни екипи дава значителни възможности за акуратната и навременна диагностика на този тип „скрити“ дефекти.

Endoscopic balloon dilatation of the olfactory cleft - a feasibility study of a novel technique in cadavers.

SUMMARYObjectiveSmell dysfunctions are common with almost 20% percent of the population affected. There are no interventional solutions for these patients. The aim of this study is to investigate the feasibility and security of the balloon dilatation technique.MethodsThis paper describes interventional steps and determines the feasibility and safety of endoscopic olfactory cleft dilatation via balloon device. We included 10 nasal cavities in the study and dilated olfactory cleft areas via balloon device.ResultsWe could smoothly perform the procedure and did not observe any fractures on the skull base or olfactory cleft of the cadavers after dilatation.ConclusionsA combination of this intervention with medical treatments can be promising for smell dysfunctions.

ROLE OF NASYA IN THE MANAGEMENT OF DYSFUNCTIONAL UTERINE BLEEDING - A REVIEW

Regular menstrual cycles with adequate quantity and duration of bleeding indicate good reproductive health, with variations in these being reflected as menorohagia, oligomenorrbea, dysmenorrbea, PCOD, infertility etc. Dysfunctional uterine bleeding is particularly common during adolescence and perimenopausal periods. It has been defined as a state of excessive uterine bleeding without clinically detectable organic, systemic and iatrogenic causes. DUB is caused by the abnormal functioning of hypothalamo – pituitary – ovarian axis.
 Nasya is a term applied generally when the medicine is administered through the nasal passage. It is considered as the most specific Panchakarama therapy used for the diseases of Siras (head) or Urdva jatru region, as nasal passage is regarded as the gateway to the head. In the present article the possible role of Nasya in the management of dysfunctional uterine bleeding is discussed. Nasya indirectly work on the entire body by improving the functioning of central nervous system and endocrine glands. The neurons which stimulate production of GnRH, originates from the olfactory area and GnRH is the regulator of gonadotropin hormones. The hormones of menstruation are under the control of these secreted by the pituitary. Nasya which is considered as having direct action on neuro-endocrinological system may regulate HPO axis and normalize the menstruation.

Experimental tracking and numerical mapping of novel coronavirus micro-droplet deposition through nasal inhalation in the human respiratory system.

It is essential to study the viral droplet’s uptake in the human respiratory system to better control, prevent, and treat diseases. Micro-droplets can easily pass through ordinary respiratory masks. Therefore, the SARS-COV-2 transmit easily in conversation with a regular mask with 'silent spreaders' in the most physiological way of breathing through the nose, indoor and at rest condition. The results showed that the amount of deposited micro-droplets in the olfactory epithelium area is low. Also, due to receptors and long droplet residence time in this region, the possibility of absorption increases in the cribriform plate. This phenomenon eventually could lead to brain lesion damage and, in some cases, leads to stroke. In all inlet flow rates lower than 30 L/min inlet boundary conditions, the average percentage of viral contamination for upper respiratory tract is always less than 50% and more than 50% for the lungs. At 6L/min and 15L/min flow rates, the average percentage of lung contamination increases to more than 87%, which due to the presence of the Coronavirus receptor in the lungs, the involvement of the lungs increases significantly. This study's other achievements include the inverse relationship between droplets deposition efficiency in some parts of the upper airway, which have the most deformation in the tract. Also, the increased deformities per minute applied to the trachea and nasal cavity, which is 1.5 times more than usual, could lead to chest and head bothers.

Platelet rich plasma in management of anosmia

Background: Anosmia is a loss of sense of smell that means inability to perceive odors. Functional anosmia is loss of smell due to nasal obstruction while organic anosmia is due to damage of the peripheral olfactory area causing permanent loss of smell as post-traumatic anosmia. Objectives: A diagnostic approach to detect the effect of platelet-rich plasma (PRP) injection in the olfactory area as a treatment for anosmia. Study design and methodology: A prospective study was done in otorhinolaryngology department, Aswan university hospital from June 2018 to August 2019, 80 patients were fulfilling the inclusion criteria presented with anosmia were enrolled from otorhinolaryngology outpatient to share in this study. Approximately an amount of 1mL of PRP was injected in each nasal cavity in the olfactory area (located on superior turbinate and superior portion of lateral and medial walls of nasal cavity) guided by nasal endoscope. The procedure is done with follow-up of patients after 1 month. Results: Results of our study revealed that 46 out of 80 patients (57.5%) said that “their smell came back” while 34 out of 80 patients (42.5%) showed no improvement, thus these results show no statistical significance between proportion in a group showing improvement and proportion in the group showing no improvement. 5 patients with idiopathic anosmia improved with 100% ratio. Conclusion: Although there is no statistical significance difference between the two groups of patients all patients with idiopathic anosmia were improved.

Post-traumatic olfactory loss and brain response beyond olfactory cortex

Olfactory impairment after a traumatic impact to the head is associated with changes in olfactory cortex, including decreased gray matter density and decreased BOLD response to odors. Much less is known about the role of other cortical areas in olfactory impairment. We used fMRI in a sample of 63 participants, consisting of 25 with post-traumatic functional anosmia, 16 with post-traumatic hyposmia, and 22 healthy controls with normosmia to investigate whole brain response to odors. Similar neural responses were observed across the groups to odor versus odorless stimuli in the primary olfactory areas in piriform cortex, whereas response in the frontal operculum and anterior insula (fO/aI) increased with olfactory function (normosmia > hyposmia > functional anosmia). Unexpectedly, a negative association was observed between response and olfactory perceptual function in the mediodorsal thalamus (mdT), ventromedial prefrontal cortex (vmPFC) and posterior cingulate cortex (pCC). Finally, connectivity within a network consisting of vmPFC, fO, and pCC could be used to successfully classify participants as having functional anosmia or normosmia. We conclude that, at the neural level, olfactory impairment due to head trauma is best characterized by heightened responses and differential connectivity in higher-order areas beyond olfactory cortex.

Individual odor hedonic perception is coded in temporal joint network activity

IntroThe human sense of smell is highly individual and characterized by a strong variability in the perception and evaluation of olfactory stimuli, depending on cultural imprint and current physiological conditions. Since this individual perspective has often been neglected in fMRI studies on olfactory hedonic coding, this study focuses on the neuronal activity and connectivity patterns resulting from subject-specific olfactory stimulation. Methods: Thirty-one normosmic participants took part in a fMRI block designed paradigm consisting of three olfactory stimulation sessions. The most pleasant and unpleasant odors were individually specified during a pre-test for each participant and validated in the main experiment. Mean activation and functional connectivity analysis focusing on the right and left piriform cortex were performed for the predefined olfactory regions-of-interest (ROIs) and compared between the three olfactory conditions. Results: Individual unpleasant olfactory stimulation as compared to pleasant or neutral did not alter mean BOLD activation in the predefined olfactory ROIs but led to a change in connectivity pattern in the right piriform cortex. Conclusion: Our data suggests that the individual pleasantness of odors is not detectable by average BOLD magnitude changes in primary or secondary olfactory brain areas, but reflected in temporal patterns of joint activation that create a network between the right piriform cortex, the left insular cortex, the orbitofrontal cortex, and the precentral gyrus. This network may serve the evolutionary defense mechanism of olfaction by preparing goal-directed action.

The Spatial and Cell-Type Distribution of SARS-CoV-2 Receptor ACE2 in the Human and Mouse Brains.

By engaging angiotensin-converting enzyme 2 (ACE2 or Ace2), the novel pathogenic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) invades host cells and affects many organs, including the brain. However, the distribution of ACE2 in the brain is still obscure. Here, we investigated the ACE2 expression in the brain by analyzing data from publicly available brain transcriptome databases. According to our spatial distribution analysis, ACE2 was relatively highly expressed in some brain locations, such as the choroid plexus and paraventricular nuclei of the thalamus. According to cell-type distribution analysis, nuclear expression of ACE2 was found in many neurons (both excitatory and inhibitory neurons) and some non-neuron cells (mainly astrocytes, oligodendrocytes, and endothelial cells) in the human middle temporal gyrus and posterior cingulate cortex. A few ACE2-expressing nuclei were found in a hippocampal dataset, and none were detected in the prefrontal cortex. Except for the additional high expression of Ace2 in the olfactory bulb areas for spatial distribution as well as in the pericytes and endothelial cells for cell-type distribution, the distribution of Ace2 in the mouse brain was similar to that in the human brain. Thus, our results reveal an outline of ACE2/Ace2 distribution in the human and mouse brains, which indicates that the brain infection of SARS-CoV-2 may be capable of inducing central nervous system symptoms in coronavirus disease 2019 (COVID-19) patients. Potential species differences should be considered when using mouse models to study the neurological effects of SARS-CoV-2 infection.

Structural and metabolic brain abnormalities in COVID-19 patients with sudden loss of smell.

ObjectivesSudden loss of smell is a very common symptom of coronavirus disease 19 (COVID-19). This study characterizes the structural and metabolic cerebral correlates of dysosmia in patients with COVID-19.MethodsStructural brain magnetic resonance imaging (MRI) and positron emission tomography with [18F]-fluorodeoxyglucose (FDG-PET) were prospectively acquired simultaneously on a hybrid PET-MR in 12 patients (2 males, 10 females, mean age: 42.6 years, age range: 23–60 years) with sudden dysosmia and positive detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on nasopharyngeal swab specimens. FDG-PET data were analyzed using a voxel-based approach and compared with that of a group of healthy subjects.ResultsBilateral blocking of the olfactory cleft was observed in six patients, while subtle olfactory bulb asymmetry was found in three patients. No MRI signal abnormality downstream of the olfactory tract was observed. Decrease or increase in glucose metabolism abnormalities was observed (p < .001 uncorrected, k ≥ 50 voxels) in core olfactory and high-order neocortical areas. A modulation of regional cerebral glucose metabolism by the severity and the duration of COVID-19-related dysosmia was disclosed using correlation analyses.ConclusionsThis PET-MR study suggests that sudden loss of smell in COVID-19 is not related to central involvement due to SARS-CoV-2 neuroinvasiveness. Loss of smell is associated with subtle cerebral metabolic changes in core olfactory and high-order cortical areas likely related to combined processes of deafferentation and active functional reorganization secondary to the lack of olfactory stimulation.

Odor Canopy: A Method for Comfortable Odorant Delivery in MRI.

Functional magnetic resonance imaging (fMRI) has become the leading method for measuring the human brain response to sensory stimuli. However, olfaction fMRI lags behind vision and audition fMRI for 2 primary reasons: First, the olfactory brain areas are particularly susceptible to imaging artifacts, and second, the olfactory stimulus is particularly difficult to control in the fMRI environment. A component of the latter is related to the odorant delivery human–machine interface, namely the point where odorants exit the dispensing apparatus to reach at the nose. Previous approaches relied on either nasal cannulas or nasal masks, each associated with particular drawbacks and discomforts. Here, we provide detailed descriptions and instructions for transforming the MRI head-coil into an olfactory microenvironment, or odor canopy, where odorants can be switched on and off in less than 150 ms without cannula or mask. In a proof-of-concept experiment, we demonstrate that odor canopy provides for clearly dissociable odorant presence and absence, with no nonolfactory cues. Moreover, we find that odor canopy is rated more comfortable than nasal mask, and we demonstrate that using odor canopy in the fMRI generates a typical olfactory brain response. We conclude in recommending this approach for minimized discomfort in fMRI of olfaction.

Variation in the Sensory Space of Three-spined Stickleback Populations.

The peripheral sensory systems, whose morphological attributes help determine the acquisition of distinct types of information, provide a means to quantitatively compare multiple modalities of a species' sensory ecology. We used morphological metrics to characterize multiple sensory modalities-the visual, olfactory, and mechanosensory lateral line sensory systems-for Gasterosteus aculeatus, the three-spined stickleback, to compare how sensory systems vary in animals that evolve in different ecological conditions. We hypothesized that the dimensions of sensory organs and correlations among sensory systems vary in populations adapted to marine and freshwater environments, and have diverged further among freshwater lake-dwelling populations. Our results showed that among environments, fish differed in which senses are relatively elaborated or reduced. When controlling for body length, littoral fish had larger eyes, more neuromasts, and smaller olfactory tissue area than pelagic or marine populations. We also found differences in the direction and magnitude of correlations among sensory systems for populations even within the same habitat type. Our data suggest that populations take different trajectories in how visual, olfactory, and lateral line systems respond to their environment. For the populations we studied, sensory modalities do not conform in a predictable way to the ecological categories we assigned.

Human Olfaction at the Intersection of Language, Culture, and Biology

The human sense of smell can accomplish astonishing feats, yet there remains a prevailing belief that olfactory language is deficient. Numerous studies with English speakers support this view: there are few terms for odors, odor talk is infrequent, and naming odors is difficult. However, this is not true across the world. Many languages have sizeable smell lexicons - smell is even grammaticalized. In addition, for some cultures smell talk is more frequent and odor naming easier. This linguistic variation is as yet unexplained but could be the result of ecological, cultural, or genetic factors or a combination thereof. Different ways of talking about smells may shape aspects of olfactory cognition too. Critically, this variation sheds new light on this important sensory modality.

Brain and Nasal Cavity Anatomy of the Cynomolgus Monkey: Species Differences from the Viewpoint of Direct Delivery from the Nose to the Brain.

Based on structural data on the nasal cavity and brain of the cynomolgus monkey, species differences in the olfactory bulb and cribriform plate were discussed from the viewpoint of direct delivery from the nose to the brain. Structural 3D data on the cynomolgus monkey skull were obtained using X-ray computed tomography. The dimensions of the nasal cavity of the cynomolgus monkey were 5 mm width × 20 mm height × 60 mm depth. The nasal cavity was very narrow and the olfactory region was far from the nostrils, similar to rats and humans. The weight and size of the monkey brain were 70 g and 55 mm width × 40 mm height × 70 mm depth. The olfactory bulb of monkeys is plate-like, while that of humans and rats is bulbar, suggesting that the olfactory area connected with the brain of monkeys is narrow. Although the structure of the monkey nasal cavity is similar to that of humans, the size and shape of the olfactory bulb are different, which is likely to result in low estimation of direct delivery from the nose to the brain in monkeys.

Structural brain plasticity induced by early blindness.

It is well established that early blindness results in behavioural adaptations. While the functional effects of visual deprivation have been well researched, anatomical studies are scarce. The aim of this study was to investigate whole brain structural plasticity in a mouse model of congenital blindness. Volumetric analyses were conducted on high-resolution MRI images and histological sections from the same brains. These morphometric measurements were compared between anophthalmic and sighted ZRDBA mice obtained by breeding ZRDCT and DBA mice. Results from MRI analyses using the Multiple Automatically Generated Templates (MAGeT) method showed smaller volume for the primary visual cortex and superior colliculi in anophthalmic compared with sighted mice. Deformation-based morphometry revealed smaller volumes within the dorsal lateral geniculate nuclei and the lateral secondary visual cortex and larger volumes within olfactory areas, piriform cortex, orbital areas and the amygdala, in anophthalmic compared with sighted mice. Histological analyses revealed a larger volume for the amygdala and smaller volume for the superior colliculi, primary visual cortex and medial secondary visual cortex, in anophthalmic compared with sighted mice. The absence of superficial visual layers of the superior colliculus and the thinner cortical layer IV of the primary and secondary visual cortices may explain the smaller volume of these areas, although this was observed in a limited sample. The present study shows large-scale brain plasticity in a mouse model of congenital blindness. In addition, the congruence of MRI and histological findings support the use of MRI to investigate structural brain plasticity in the mouse.

The CSF-Contacting Nucleus Receives Anatomical Inputs From the Cerebral Cortex: A Combination of Retrograde Tracing and 3D Reconstruction Study in Rat.

ObjectiveThis study aimed to investigate the direct monosynaptic projections from cortical functional regions to the cerebrospinal fluid (CSF)-contacting nucleus for understanding the functions of the CSF-contacting nucleus.MethodsThe Sprague–Dawley rats received cholera toxin B subunit (CB) injections into the CSF-contacting nucleus. After 7–10 days of survival time, the rats were perfused, and the whole brain and spinal cord were sliced under a freezing microtome at 40 μm. All sections were treated with the CB immunofluorescence reaction. The retrogradely labeled neurons in different cortical areas were revealed under a confocal microscope. The distribution features were further illustrated under 3D reconstruction.ResultsThe retrogradely labeled neurons were identified in the olfactory, orbital, cingulate, insula, retrosplenial, somatosensory, motor, visual, auditory, association, rhinal, and parietal cortical areas. A total of 12 functional areas and 34 functional subregions showed projections to the CSF-contacting nucleus in different cell intensities.ConclusionAccording to the connectivity patterns, we conclude that the CSF-contacting nucleus participates in cognition, emotion, pain, visceral activity, etc. The present study firstly reveals the cerebral cortex→CSF-contacting nucleus connections, which implies the multiple functions of this special nucleus in neural and body fluid regulations.