Most gyrodactylids have a haptor armed with a pair of hamuli, two connecting bars and 16 marginal hooks. In some gyrodactylids, however, the haptor is disc-shaped and reinforced by additional sclerites. The genus Polyclithrum has arguably the most elaborate haptor in this group. This study aimed to gain better understanding of the anatomy of Polyclithrum by examining neuromusculature and haptoral armament of Polyclithrum ponticum, a species parasitizing Mugil cephalus in the Black Sea, with emphasis on haptoral sclerites and musculature in connection with host-attachment mechanisms. Musculature was stained by phalloidin, the nervous system by anti-serotonin and anti-FMRFamide antibodies, and haptoral sclerites were visualized in reflected light. The study provided new information on sclerites: in addition to previously described supplementary sclerites (A1–6), ear-shaped sclerites (ESSs) and two paired groups of ribs, reflected light revealed a rod-shaped process on the ESSs and a pair of small posterior sclerites. The sclerites were shown to be operated by 16 muscles, the most prominent of which were two transverse muscles connecting the hamular roots, three muscles attached to sclerite A2, the muscle fibres of anterior ribs and a set of extrinsic muscles. The nervous system consists of a pair of cerebral ganglia connected by a commissure and three pairs of nerve cords that unite in the haptor to form a loop between the opposite cords. The arrangement of sclerites and muscles suggests that Polyclithrum initiates the attachment by clamping a host's surface with longitudinally folded haptor and then secures its position with marginal hooks.

Dietary restriction of carbohydrate has been demonstrated to be beneficial for nervous system dysfunction in animal models and may be beneficial for human chronic pain. The purpose of this review is to assess the impact of a low-carbohydrate/ketogenic diet on the adult nervous system function and inflammatory biomarkers to inform nutritional research for chronic pain. An electronic database search was carried out in May 2021. Publications were screened for prospective research with dietary carbohydrate intake <130 g per day and duration of ≥2 weeks. Studies were categorised into those reporting adult neurological outcomes to be extracted for analysis and those reporting other adult research outcomes. Both groups were screened again for reported inflammatory biomarkers. From 1548 studies, there were 847 studies included. Sixty-four reported neurological outcomes with 83% showing improvement. Five hundred and twenty-three studies had a different research focus (metabolic n = 394, sport/performance n = 51, cancer n = 33, general n = 30, neurological with non-neuro outcomes n = 12, or gastrointestinal n = 4). The second screen identified sixty-three studies reporting on inflammatory biomarkers, with 71% reporting a reduction in inflammation. The overall results suggest a favourable outcome on the nervous system and inflammatory biomarkers from a reduction in dietary carbohydrates. Both nervous system sensitisation and inflammation occur in chronic pain, and the results from this review indicate it may be improved by low-carbohydrate nutritional therapy. More clinical trials within this population are required to build on the few human trials that have been done.

The present report describes two cases of infection by Molossinema wimsatti in the brain of Pallas's mastiff bats (Molossus molossus). The first bat was captured and killed by a domestic cat in a suburban area of the municipality of Patos, Paraiba, northeastern Brazil. The second bat was found crawling on the ground in the same area before dying. No gross lesions were found at necropsy. Histology of the central nervous system revealed filarioid nematodes in the brain ventricles and cerebellum. There were adults, subadults and eggs, the latter sometimes containing microfilariae. No inflammatory response was observed in bat 1, while bat 2 presented a mild lymphoplasmacytic meningoencephalitis. Three nematodes were recovered and submitted for parasitological examination. The diagnosis of M. wimsatti infection was based on the histomorphological and parasitological characteristics of the agent and its location in the brain ventricular system of insectivorous bats. The infection likely occurs in other insectivorous bats from South American and Caribbean countries but may be overlooked.

Data on the interposition of the immunoreactive nerve cords in Cercaria parvicaudata Stunkard & Shaw, 1931 (Trematoda: Renicolidae) and its chaetotaxy were obtained. The nervous system of C. parvicaudata was described using immunostaining of 5-hydroxytryptamine and FMRFamide immunoreactive nerve elements. The morphology and distribution of sensory receptors were analysed using scanning electron microscopy and the silver nitrate impregnation technique. Our integrated approach to the study of the nervous system revealed a clear colocalization of surface papillae with nerve cords and commissures in C. parvicaudata. The structure of the nervous system in C. parvicaudata differs partly from the classical model that defines the entire nomenclature of chaetotaxy.

An interactional model of brain function is postulated, in which activity and reactivity are basic properties of the central nervous system from the very beginning. Variability is an essential aspect of normal functioning. Primary or indiscriminate variability consists of the development of many strategies for the execution of motor acts. It is predominant during fetal age and infancy. Toddler age is characterized by secondary or adaptive variability, which reflects the ability to select the adequate strategy at the right moment. This is important for the development of proper planning of movement patterns and is a prerequisite for skill development. Recognition of the types and quality of variability helps to detect developmental disorders at an early age.

Some ideas return after the briefest of exiles: reductionism is back in vogue. Existential questions – about who we are, about our origins and future, about what is valuable – no longer require difficult soul searching, especially when straightforward answers are expected from the neurosciences. History is being rewritten with the brain as its centrepiece; the search for great men and big ideas of the past begins again. William Cullen (1710–90), whose work on neurosis was once part of the history of psychoanalysis, is now well placed to become part of such a neuro-history. This article attempts to subvert this process, by rebuilding the original meaning of neurosis through Cullen’s physiological and medical works, in comparison with his predecessor, Robert Whytt (1714–66), and illustrating this meaning using one particular neurosis: hypochondriasis. The result is a more complicated version of neurosis which, importantly, carries significant insights into the nature and practice of medicine. Moreover, this article examines how Cullen’s standing fell in the 1820s as British physicians and surgeons turned to an idea which promised to reform medicine: pathological anatomy. When these hopes faded, Cullen became a figure obsessed with the nerves. This image has survived to the present, a blank canvas onto which any theory can be projected. It also values precisely what Cullen warned against: simplistic explanations of the body and disease, and unthinking confidence in the next big idea or silver bullet. Neurosis was not simply a nervous ailment, but it is a warning against reductionism in history making.

Cytokines (e.g. various interleukins and subfamily members, tumor necrosis factors, interferons, chemokines and growth factors) act in the brain as immunoregulators and neuromodulators. Over a decade ago, the integrative article ‘Immunoregulators in the Nervous System’ (Neurosci Biobehav Rev 1991; 15: 185–215) provided a comprehensive framework of pivotal issues on cytokines and the nervous system that recently have been extensively studied. Cytokine profiles in the brain, including cytokine generation and action, have been studied in multiple models associated with neuropathophysiological conditions. These include: (1) acute conditions and disorders such as stroke (cerebral ischemia or infarction and intracranial hemorrhage), traumatic brain injury, spinal cord injury and acute neuropathies; (2) chronic neurodegenerative disorders and chronic conditions, including Alzheimer's disease, Parkinson's disease, neuropathic pain, epilepsy and chronic neuropathies; (3) brain infections, including bacterial meningitis and encephalitis; (4) brain tumors; (5) neuroimmunological disorders per se, such as multiple sclerosis; (5) psychiatric disorders, including schizophrenia and depression; (6) neurological and neuropsychiatric manifestations associated with non- central nervous system (CNS) disorders such as peripheral cancer, liver, kidney and metabolic compromise, and peripheral infectious and inflammatory conditions; and (7) cytokine immunotherapy, which can be accompanied by neuropsychiatric manifestations when administered either via peripheral or brain routes. Cytokine profiles have also been studied in multiple animal models challenged with inflammatory, infectious, chemical, malignant and stressor insults. Essentially data show that cytokines play a pivotal role in multiple neuropathophysiological processes associated with different types of disorders and insults. Cytokine expression and action in the brain shows a different profile across conditions, but some similarities exist. Under a defined temporal sequence, cytokine involvement in neuroprotection or the induction of a deleterious pathophysiological cascade and in resolution/healing is proposed depending on the type of cytokine. In the brain, functional interactions among cytokines, balance between pro-inflammatory and anti-inflammatory cytokines and functional interactions with neurotransmitters and neuropeptides play a pivotal role in the overall cytokine profile, pattern of neuropathophysiological cascades, and quality and magnitude of neuropsychiatric manifestations. In this brief review various selected cytokine-related issues with relevance to the brain are discussed.

On the basis of esterase localization the complete nervous system has been visualized in Olveria indica Thapar & Sinha, 1945, a paramphistome from the rumen of cattle, recorded for the first time from the north-east region of India. The basic number of posterior longitudinal nerves (i.e., 3 pairs) is the same as in other paramphistomes; four pairs of anterior longitudinal nerves are present, there being an extra pair of pharyngeal nerves. Conspicuous differences in the innervation patterns were observed, mainly in the innervation of the genital atrial region and acetabulum. The presence of prominent longitudinal connections, joining the anterior and posterior dorsal nerves and the anterior and posterior ventral nerves on either side, is a feature not hitherto found in other paramphistome species. The details of the course of all the nerves and their branches are discussed.

Adult males of Schistosoma mansoni were preincubated in 5-hydroxtryptamine (5HT) and processed through the glyoxylic acid fluorescence technique to visualize 5HT-containing neural elements. 5HT flourescence was seen as a series of cross-sectional rings beginning behind the ventral sucker toward the tail end. The rings were connected by two lateral nerve cords running longitudinally along the whole lenght of the worms.

The localization and distribution of the serotoninergic components of the nervous system in the hydatid organism, Echinococcus granulosus, were determined by immunocytochemical techniques in conjunction with confocal scanning laser microscopy (CSLM). The distribution of serotonin immunoreactivity (IR) paralleled that previously described for cholinesterase activity, although it was more widespread. Nerve cell bodies and nerve fibres immunoreactive for 5-HT were present throughout the central nervous system (CNS), occurring in the paired lateral, posterior lateral and rostellar ganglia, their connecting commissures and nerve rings in the scolex and in the ten longitudinal nerve cords that run posteriorly throughout the body of the worm. A large population of nerve cell bodies was associated with the lateral nerve cords. In the peripheral nervous system (PNS), immunoreactive nerve fibres occurred in well-developed nerve plexuses innervating the somatic musculature and the musculature of the rostellum and suckers. The genital atrium and associated reproductive ducts were richly innervated with serotoninergic nerve cell bodies and nerve fibres.

A detailed morphological investigation of the anterior sensory organs, the nerve ring and a glomerulus-like structure in male Onchocerca volvulus was performed by means of electron microscopy. The 8 head papillae are arranged in the common 4 + 4 pattern of most filarial worms in circles around the mouth opening. The amphidial openings are found between the circles of inner and outer papillae on both sides of the mouth. Inside, several additional nerve axons are seen in the tissue of the anterior tip not related to one of the identified papillar structures. The inner and outer papillae exhibit a remarkably different fine structure, and are part of a complex system of at least 2 different receptor cell types at the anterior tip of the worm. The amphidial channel contains 8 modified cilia; accessory axons are associated with the cytoplasm of the sheath cell. The anterior nerve ring of male worms is located about 150 µm posterior from the outermost tip of the head region. It consists of several fibres coiled around the oesophagus. The comparison of the fine structure of the central nervous system did not show the expected morphological differences associated with the heterogeneous age distribution in the natural worm population. This was in contrast to previous findings with respect to tissues in different parts of the worm. The study also provides the first evidence that suggests the existence of an excretory organ in a filarial worm in the region of the anterior nerve ring. Paired glomerulus-like structures in the lateral chords and a canal formed by a projection of the basal zone of the cuticle were identified.

Specific antisera, directed against the highly conserved C-terminal hexapeptide amide of mammalian pancreatic poly-peptide (PP) and the invertebrate peptide FMRFamide, have been used in conjunction with post-embedding, IgG-conjugated colloidal gold immunostaining to demonstrate peptide immunoreactivity at subcellular level in the nervous system of adult Diclidophora merlangi. Gold labelling revealed that immunoreactivity for PP and FMRFamide was localized exclusively in dense-cored vesicles occupying the majority of axons in the central nervous system. Double-labelling demonstrated an apparent co-localization of PP and FMRFamide in the same dense-cored vesicles. Antigen pre-absorption experiments indicated cross-reactivity of the two antisera as unlikely, and that some if not all of the PP/FMRFamide immunostaining in the parasite was due to a neuropeptide F-like peptide.

A post-embedding immunogold technique has been used to examine the subcellular distribution of immunoreactivities to vertebrate pancreatic polypeptide (PP) and to the invertebrate peptide, FMRFamide within the central nervous system (CNS) of the nematode, Ascaris suum. Gold labelling of peptide was localized exclusively over dense-cored vesicles within nerve cell bodies, nerve axons and nerve terminals of the main ganglia and nerve cords in the CNS. Double-labelling of peptides demonstrated an apparent co-localization of PP and FMRFamide immunoreactivities in the same dense-cored vesicles, although populations of dense-cored vesicles that labelled solely for FMRFamide were also evident. Antigen preabsorption studies indicated little or no cross-reactivity between the two antisera.

Neuropeptide F (Moniezia expansa) immunoreactivity (NPF-IR) has been detected in the nervous system of plerocercoid and adult stages of the gull-tapeworm Diphyllobothrium dendriticum, using immunocytochemical methodology. The application of the antiserum for this authentic flatworm neuropeptide to whole-mounts and frozen sections of the worm has resulted in new information about its neuroanatomy. Thus, at regular intervals, transverse nerves extend from the main nerve cords laterally, joining the longitudinal lateral minor cords in the cortical parenchyma. In the adult worm, the transverse nerves are located at the posterior border of each proglottis. The medullary parenchyma lacks NPF-IR. The NPF-immunoreactive cell bodies are bi- to multipolar and preferentially located in the peripheral nervous system, in close association with the holdfast musculature of the scolex and the extensive body musculature. NPF-IR was observed in the innervation to the muscular ducts of the reproductive system. The pattern of NPF-IR was compared with that recorded for RFamide- and 5-HT-IR and double-immunostaining has revealed separate populations of serotoninergic and peptidergic neurones.