OASIS evaluation of the French surveillance network for antimicrobial resistance in diseased animals (RESAPATH): success factors underpinning a well-performing voluntary system.

Antimicrobial resistance is a One Health issue requiring the development of surveillance systems in the human, environmental and animal sectors. In the European Economic Area, the surveillance of antimicrobial resistance in zoonotic pathogens and indicator bacteria in healthy food-producing animals is required legally, while countries are also expected to extend their surveillance to diseased animals in the frame of national action plans. In this context, evaluating existing antimicrobial resistance surveillance systems in animal health is important to improve systems in place, but also to help other countries learn from these experiences, understand success factors and anticipate challenges. With this aim, the French surveillance network for antimicrobial resistance in bacteria from diseased animals (RESAPATH) was evaluated using the Outil d'Analyse des Systèmes d'Information en Santé (OASIS) assessment tool. Key performance factors included (i) a strong and inclusive central institutional organisation defining clear and well-accepted surveillance objectives, scope and procedures, (ii) strong skills in epidemiology and microbiology and (iii) a win-win approach enabling the voluntary participation of 71 field laboratories and where free annual proficiency testing plays a pivotal role. The main area for improvement of RESAPATH was its time-consuming data management system.

Developing an Optical Interferometric Detection Method based biosensor for detecting specific SARS-CoV-2 immunoglobulins in Serum and Saliva, and their corresponding ELISA correlation.

The standard rapid approach for the diagnosis of coronavirus disease 2019 (COVID-19) is the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA. The detection of specific anti-SARS-CoV-2 immunoglobulins is crucial for screening people who have been exposed to the virus, whether or not they presented symptoms. Recent publications report different methods for the detection of specific IgGs, IgMs, and IgAs against SARS-CoV-2; these methods mainly detect immunoglobulins in the serum using conventional techniques such as rapid lateral flow tests or enzyme-linked immunosorbent assay (ELISA). In this article, we report the production of recombinant SARS-CoV-2 spike protein and the development of a rapid, reliable, cost-effective test, capable of detecting immunoglobulins in serum and saliva samples. This method is based on interferometric optical detection. The results obtained using this method and those obtained using ELISA were compared. Owing to its low cost and simplicity, this test can be used periodically for the early detection, surveillance, detection of immunity, and control of the spread of COVID-19.

DAT isn't all that: cocaine reward and reinforcement require Toll-like receptor 4 signaling.

The initial reinforcing properties of drugs of abuse, such as cocaine, are largely attributed to their ability to activate the mesolimbic dopamine system. Resulting increases in extracellular dopamine in the nucleus accumbens (NAc) are traditionally thought to result from cocaine's ability to block dopamine transporters (DATs). Here we demonstrate that cocaine also interacts with the immunosurveillance receptor complex, Toll-like receptor 4 (TLR4), on microglial cells to initiate central innate immune signaling. Disruption of cocaine signaling at TLR4 suppresses cocaine-induced extracellular dopamine in the NAc, as well as cocaine conditioned place preference and cocaine self-administration. These results provide a novel understanding of the neurobiological mechanisms underlying cocaine reward/reinforcement that includes a critical role for central immune signaling, and offer a new target for medication development for cocaine abuse treatment.

Comparative evaluation of three surveillance systems for infectious equine diseases in France and implications for future synergies.

It is necessary to assess surveillance systems for infectious animal diseases to ensure they meet their objectives and provide high-quality health information. Each system is generally dedicated to one disease and often comprises various components. In many animal industries, several surveillance systems are implemented separately even if they are based on similar components. This lack of synergy may prevent optimal surveillance. The purpose of this study was to assess several surveillance systems within the same industry using the semi-quantitative OASIS method and to compare the results of the assessments in order to propose improvements, including future synergies. We have focused on the surveillance of three major equine diseases in France. We have identified the mutual and specific strengths and weaknesses of each surveillance system. Furthermore, the comparative assessment has highlighted many possible synergies that could improve the effectiveness and efficiency of surveillance as a whole, including the implementation of new joint tools or the pooling of existing teams, tools or skills. Our approach is an original application of the OASIS method, which requires minimal financial resources and is not very time-consuming. Such a comparative evaluation could conceivably be applied to other surveillance systems, other industries and other countries. This approach would be especially relevant to enhance the efficiency of surveillance activities when resources are limited.

Opioid activation of toll-like receptor 4 contributes to drug reinforcement.

Opioid action was thought to exert reinforcing effects solely via the initial agonism of opioid receptors. Here, we present evidence for an additional novel contributor to opioid reward: the innate immune pattern-recognition receptor, toll-like receptor 4 (TLR4), and its MyD88-dependent signaling. Blockade of TLR4/MD2 by administration of the nonopioid, unnatural isomer of naloxone, (+)-naloxone (rats), or two independent genetic knock-outs of MyD88-TLR4-dependent signaling (mice), suppressed opioid-induced conditioned place preference. (+)-Naloxone also reduced opioid (remifentanil) self-administration (rats), another commonly used behavioral measure of drug reward. Moreover, pharmacological blockade of morphine-TLR4/MD2 activity potently reduced morphine-induced elevations of extracellular dopamine in rat nucleus accumbens, a region critical for opioid reinforcement. Importantly, opioid-TLR4 actions are not a unidirectional influence on opioid pharmacodynamics, since TLR4(-/-) mice had reduced oxycodone-induced p38 and JNK phosphorylation, while displaying potentiated analgesia. Similar to our recent reports of morphine-TLR4/MD2 binding, here we provide a combination of in silico and biophysical data to support (+)-naloxone and remifentanil binding to TLR4/MD2. Collectively, these data indicate that the actions of opioids at classical opioid receptors, together with their newly identified TLR4/MD2 actions, affect the mesolimbic dopamine system that amplifies opioid-induced elevations in extracellular dopamine levels, therefore possibly explaining altered opioid reward behaviors. Thus, the discovery of TLR4/MD2 recognition of opioids as foreign xenobiotic substances adds to the existing hypothesized neuronal reinforcement mechanisms, identifies a new drug target in TLR4/MD2 for the treatment of addictions, and provides further evidence supporting a role for central proinflammatory immune signaling in drug reward.

Risk of early breastfeeding cessation among symmetrical, small for gestational age infants.

BACKGROUND: Many studies have shown that children born small for gestational age are at a metabolic disadvantage. Breastfeeding is associated with reduced risk of developing metabolic syndrome. OBJECTIVE: To determine whether ponderal index, weight, length or head circumference at birth affect early exclusive breastfeeding discontinuation. DESIGN: Information from medical records of full-term infants attending the same paediatric clinic was used to examine the relationship between birth size and failure to breastfeed within 28 days after birth. Details of demographics and diagnoses were prospectively recorded. Feeding method was assessed at each child visit by their healthcare provider. Feeding practices were compared between infants of high, normal and low ponderal index at birth. RESULTS: Multivariate models (p's ≤ 0.02) confirmed that the chance of exclusive breastfeeding continuation within 4 weeks of life was less in infants whose birth weight was below 2780 g or whose neonatal head circumference was < 33 cm. Birth length did not account for this effect. Ponderal index was not associated with a higher risk of early discontinuation of exclusive breastfeeding. CONCLUSIONS: This study reports that birth weight ≥ 2780 g and head circumference at birth ≥ 33 cm are independent predictors of breastfeeding onset success.

Factors Associated with Owner-Reported Euthanasia in Equids in France.

There is limited evidence regarding the proportion of dead equids in France that were euthanized and the factors influencing the decision-making of euthanasia. The better understanding of which could facilitate research on improvement of welfare, especially on end of life issues. The aim of this study was to estimate the proportion of euthanasia and identify associated factors in equids in France. A web-based survey was created and distributed by the French horse and riding institute to owners who reported an equine death between April 2017 and April 2018 (n = 5 158). Factors associated with euthanasia were identified using a multivariable logistic regression model. The percentage of responses was 10.6% (n = 548/5 158; 95% CI 9.8% to 11.5%). The proportion of euthanasia was 71.0% (n = 389/548; 95% CI 67.2% to 74.8%). The factors "age category", "cause of natural death or reason for euthanasia" and "the length of time during which the animal was reported to be ill by the owner" were significantly associated with euthanasia (P <0.001). The results highlighted that a large majority of owners faced euthanasia decisions and our findings could support veterinarians and owners to better prepare for such an eventuality.

Identification of levers for improving dead equine traceability: A survey of French equine owners' perception of regulatory procedures following their animal's death.

The core of the French equine traceability system is the census database (SIRE) managed by the French horse and riding institute (IFCE). Following the death of an equine, owners are legally obliged to take charge of cadaver removal by contacting a rendering company directly or after registration on the national ATM-équidés ANGEE association (ATM) website, which proposes negotiated prices for removal and recording of the death in the SIRE database. Despite these offers, ATM notes few users. Owners are also legally obliged to return the equine's passport to the IFCE, but only 30-40 % of owners comply with the regulation. Rendering companies register data on equine mortality in the fallen stock data interchange database (FSDI), but it is difficult to cross-reference these data with SIRE data. Consequently, the death of equines is not well registered in the SIRE database. The objective of the present study was to identify levers that could be used to improve dead equine traceability by i) investigating the level of satisfaction of equine owners with ATM and rendering company services; and ii) investigating the drawbacks of owners having to return the passport to the IFCE. An online survey was designed and distributed by email to the 5 158 owners who used ATM services between April 2017 and April 2018. The response rate was 16.4 %. Most owners were satisfied by ATM and rendering company services. The lack of simple and quick removal procedures and the lack of any connection between ATM and the rendering companies were among the main drawbacks identified. Regarding the return of the passport to the IFCE, most responding owners returned it through the rendering company (65 %) or directly (2 %). The passport was returned significantly more frequently when requested by the renderers. The main reason for not providing the passport was the owner wanted to keep it as a souvenir. These results suggest that ATM and the rendering companies are key players in dead equine traceability. ATM services should be developed through the establishment of a direct connection with rendering companies to accelerate the cadaver removal request and to allow the cross-referencing of data between the ATM, FSDI and SIRE databases for a better dead equine traceability. Rendering companies need regulatory support to help them ask owners for the equine's passport, formalizing their contribution to equine traceability. Finally, effective communication has to be established to inform owners about the removal procedures and the regulations.

Medial prefrontal cortex determines how stressor controllability affects behavior and dorsal raphe nucleus.

The degree of behavioral control that an organism has over a stressor is a potent modulator of the stressor's impact; uncontrollable stressors produce numerous outcomes that do not occur if the stressor is controllable. Research on controllability has focused on brainstem nuclei such as the dorsal raphe nucleus (DRN). Here we find that the infralimbic and prelimbic regions of the ventral medial prefrontal cortex (mPFCv) in rats detect whether a stressor is under the organism's control. When a stressor is controllable, stress-induced activation of the DRN is inhibited by the mPFCv, and the behavioral sequelae of uncontrollable stress are blocked. This suggests a new function for the mPFCv and implies that the presence of control inhibits stress-induced neural activity in brainstem nuclei, in contrast to the prevalent view that such activity is induced by a lack of control.

[Registry of mild craniocerebral trauma: multicentre study from the Spanish Association of Pediatric emergencies]. / Registro de traumatismos craneoencefálicos leves: estudio multicéntrico de la Sociedad Española de Urgencias Pediátricas.

OBJECTIVE: To determine management practices of minor head trauma in children evaluated at Spanish Hospital Emergency Departments and to determine patient variables associated with intracranial injury. METHODS: Multicenter and prospective study during 18 months in 9 hospitals in Spain. Patients up to the age of 18 years with minor head trauma (Glasgow Coma Scale score higher than or equal to 13 on admission), treated in Emergency Departments and with a maximum onset of 72h since the traumatism, were included in the study. RESULTS: A total of 1070 patients were studied with a median age of 2.4 years (p25-75 0.9-6.4 years); 61.2% were male. The median time between head trauma and medical consultation was 1 hour (p25-75 0.6-2.5h). Skull X-rays were performed on 64.5% of the children and a head CT scan on 9%; 91.4% of X-ray and 84.4% of CT were normal. The prevalence of intracranial injury was 1.4% (95% CI: 0.8-2.3). Twenty-five point three percent of the patients were admitted; 4 (3.7%) required neurosurgical intervention during admission. None of the patients died. Multiple logistic regression analysis identified loss of consciousness (OR 4.2, 95% CI: 1.1-17; P=0.045), neurological deterioration (OR 8.8, 95% CI: 2.1-37.6; P=0.003) and cephalhaematoma (OR 14.6, 95% CI: 4.9-44; P <0.001) as independent predictors of intracranial injury. CONCLUSIONS: The combination of clinical parameters allows selection of patients with minor head trauma who need complementary explorations. In consequence, the routine use of skull X-ray in their initial evaluation is unnecessary.

Human Immunodeficiency Virus/Hepatits C Virus Coinfection in Spain: Elimination Is Feasible, but the Burden of Residual Cirrhosis Will Be Significant.

BACKGROUND: We assessed the prevalence of antibodies against hepatitis C virus (HCV-Abs) and active HCV infection in patients infected with human immunodeficiency virus (HIV) in Spain in 2016 and compared the results with those of similar studies performed in 2002, 2009, and 2015. METHODS: The study was performed in 43 centers during October-November 2016. The sample was estimated for an accuracy of 2% and selected by proportional allocation and simple random sampling. During 2016, criteria for therapy based on direct-acting antiviral agents (DAA) were at least significant liver fibrosis, severe extrahepatic manifestations of HCV, and high risk of HCV transmissibility. RESULTS: The reference population and the sample size were 38904 and 1588 patients, respectively. The prevalence of HCV-Abs in 2002, 2009, 2015, and 2016 was 60.8%, 50.2%, 37.7%, and 34.6%, respectively (P trend <.001, from 2002 to 2015). The prevalence of active HCV in 2002, 2009, 2015, and 2016 was 54.0%, 34.0%, 22.1%, and 11.7%, respectively (P trend <.001). The anti-HCV treatment uptake in 2002, 2009, 2015, and 2016 was 23.0%, 48.0%, 59.3%, and 74.7%, respectively (P trend <.001). In 2016, HCV-related cirrhosis was present in 7.6% of all HIV-infected individuals, 15.0% of patients with active HCV, and 31.5% of patients who cleared HCV after anti-HCV therapy. CONCLUSIONS: Our findings suggest that with universal access to DAA-based therapy and continued efforts in prevention and screening, it will be possible to eliminate active HCV among HIV-infected individuals in Spain in the short term. However, the burden of HCV-related cirrhosis will continue to be significant among HIV-infected individuals.

Controllable versus uncontrollable stressors bi-directionally modulate conditioned but not innate fear.

Fear conditioning and fear extinction play key roles in the development and treatment of anxiety-related disorders, yet there is little information concerning experiential variables that modulate these processes. Here we examined the impact of exposure to a stressor in a different environment on subsequent fear conditioning and extinction, and whether the degree of behavioral control that the subject has over the stressor is of importance. Rats received a session of either escapable (controllable) tail shock (ES), yoked inescapable (uncontrollable) tail shock (IS), or control treatment (home cage, HC) 7 days before fear conditioning in which a tone and foot shock were paired. Conditioning was measured 24 h later. In a second experiment rats received ES, IS or HC 24 h after contextual fear conditioning. Extinction then occurred every day beginning 7 days later until a criterion was reached. Spontaneous recovery of fear was assessed 14 days after extinction. IS potentiated fear conditioning when given before fear conditioning, and potentiated fear responding during extinction when given after conditioning. Importantly, ES potently interfered with later fear conditioning, decreased fear responding during fear extinction, and prevented spontaneous recovery of fear. Additionally, we examined if the activation of the ventral medial prefrontal cortex (mPFCv) by ES is critical for the protective effects of ES on later fear conditioning. Inactivation of the mPFCv with muscimol at the time of the initial experience with control prevented ES-induced reductions in later contextual and auditory fear conditioning. Finally, we explored if the protective effects of ES extended to an unconditioned fear stimulus, ferret odor. Unlike conditioned fear, prior ES increased the fear response to ferret odor to the same degree as did IS.

cAMP signaling in neurons: patterns of neuronal expression and intracellular localization for a novel protein, AKAP 150, that anchors the regulatory subunit of cAMP-dependent protein kinase II beta.

In mammalian brain, physiological signals carried by cyclic AMP (cAMP) seem to be targeted to effector sites via the tethering of cAMP-dependent protein kinase II beta (PKAII beta) to intracellular structures. Recently characterized A kinase anchor proteins (AKAPs) are probable mediators of the sequestration of PKAII beta because they contain a high-affinity binding site for the regulatory subunit (RII beta) of the kinase and a distinct intracellular targeting domain. To establish a cellular basis for this targeting mechanism, we have employed immunocytochemistry to 1) identify the types of neurons that are enriched in AKAPs, 2) determine the primary intracellular location of the anchor protein, and 3) demonstrate that an AKAP and RII beta are coenriched and colocalized in neurons that utilize the adenylate cyclase-cyclic AMP-dependent protein kinase (PKA) signaling pathway. Antibodies directed against rat brain AKAP 150 were used to elucidate the regional, cellular and intracellular distribution of a prototypic anchor protein in the CNS. AKAP 150 is abundant in Purkinje cells and in neurons of the olfactory bulb, basal ganglia, cerebral cortex, and other forebrain regions. In contrast, little AKAP 150 is detected in neurons of the thalamus, hypothalamus, midbrain, and hindbrain. A high proportion of total AKAP 150 is concentrated in primary branches of dendrites, where it is associated with microtubules. We also discovered that the patterns of accumulation and localization of RII beta (and PKAII beta) in brain are similar to those of AKAP 150. The results suggest that bifunctional AKAP 150 tethers PKAII beta to the dendritic cytoskeleton, thereby creating a discrete target site for the reception and propagation of signals carried by cAMP.

Estimating the incidence of equine viral arteritis and the sensitivity of its surveillance in the French breeding stock.

Equine viral arteritis (EVA) may have serious economic impact on the equine industry. For this reason, it is monitored in many countries, especially in breeding stock, to avoid its spread during breeding activities. In France, surveillance is mainly based on serological tests, since mares are not vaccinated, but difficulties in interpreting certain series of results may impair the estimation of the number of outbreaks. In this study, we propose specific rules for identifying seroconversion in order to estimate the number of outbreaks that were detected by the breeding stock surveillance component (BSSC) in France between 2006 and 2013. A consensus among multidisciplinary experts was reached to consider seroconversion as a change in antibody titer from negative to at least 32, or as an eight-fold or greater increase in antibody level. Using these rules, 239 cases and 177 outbreaks were identified. Subsequently, we calculated the BSSC's sensitivity as the ratio of the number of detected outbreaks to the total number of outbreaks that occurred in breeding stock (including unreported outbreaks) estimated using a capture-recapture model. The total number of outbreaks was estimated at 215 (95% credible interval 195-249) and the surveillance sensitivity at 82% (CrI95% 71-91). Our results confirm EVA circulation in French breeding stock, show that neutralizing antibodies can persist up to eight years in naturally infected mares and suggest that certain mares have been reinfected. This study shows that the sensitivity of the BSSC is relatively high and supports its relevance to prevent the disease spreading through mating.

Defective HSV-1 vector expressing BDNF in auditory ganglia elicits neurite outgrowth: model for treatment of neuron loss following cochlear degeneration.

The neurotrophins are a family of growth factors that play an important role in the development and maintenance of the nervous system. Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family that appears to participate in the maturation and function of mammalian auditory neurons. Forms of deafness due to varied injurious stimuli that are amenable to treatment with implantable prosthetic devices require the survival of these BDNF-responsive auditory neurons for effective outcome. To evaluate the feasibility of developing a gene therapy for deafness that may be used in conjunction with a prosthetic device, we constructed replication-defective herpes simplex virus (HSV) amplicon vectors that carry the human BDNF cDNA. Using these vectors, HSVbdnf and HSVbdnflac (expresses BDNF and Escherichia coli beta-galactosidase), we evaluated the expression and biological activity in established cell lines and explant cultures prepared from spiral ganglia of the murine ear. Gene transfer with HSVbdnf resulted in the efficient expression of human BDNF mRNA in murine fibroblasts. Using two BDNF-responsive cell lines, PC12trkB and MG87trkB, we demonstrate efficient secretion of biologically active BDNF. Finally, transduction of explanted spiral ganglia with HSVbdnflac elicited robust neuritic process outgrowth comparable to exogenously added BDNF. Overall, these data demonstrate that HSV vectors can efficiently transfer and express the BDNF gene in many cell types, including auditory neurons. Moreover, they suggest that similar vectors may be used to express the neurotrophin in auditory neurons in vivo and perhaps as adjunctive gene therapy for deafness.

Segment-related, mosaic neurogenetic pattern in the forebrain and mesencephalon of early chick embryos: I. Topography of AChE-positive neuroblasts up to stage HH18.

Histochemical mapping of AChE-positive neuroblasts in sectioned and whole-mounted preparations of the chick embryo mesencephalon and prosencephalon allows a correlation of early neural tube morphogenesis (segmentation, longitudinal compartmentation) with the heterochronic pattern of neurogenesis. One significant finding is that the initial appearance of neuroblasts in the forebrain does not follow neuromeric segmentation, but evolves in parallel with it. Early neuroblasts appear as separate, distinct groups within specific matrix territories at the center of the transverse neuromeric segments. Neighbouring segments display different spatiotemporal patterns of neurogenesis. Overall gradients of differentiation in the rostrocaudal and ventrodorsal directions are absent, whereas a clear-cut segment-related, mosaic pattern becomes evident. Notwithstanding this, gross regularities of heterochrony in the neurogenetic behavior of the different segments lead to a definition of elemental longitudinal compartments of the forebrain and mesencephalon (floor, paramedian, basal, and alar regions) on the basis of precocious differentiation of the basal region and retarded differentiation of the paramedian and alar regions.

Pimozide therapy for trigeminal neuralgia.

Pimozide was compared with carbamazepine in a double-blind crossover trial in 48 patients with trigeminal neuralgia who were refractory to medical therapy. Pimozide treatment produced greater reduction in trigeminal neuralgia symptoms than carbamazepine treatment. All of the pimozide-treated patients improved, while only 56% of carbamazepine-treated patients were relieved of their pain. Although both drugs provoked some adverse effects, it was not necessary to interrupt the trial in any case. After this 24-week trial, all patients began receiving pimozide and were followed up according to an open-label study design. In all cases, the pimozide dosage was progressively reduced until the minimal effective dose was reached. Central and peripheral mechanisms that may underlie pimozide-induced improvement are discussed.

Input to the vestibulo cerebellum and triceps brachii motoneurons during natural vestibular stimulation in frog.

The response of cerebellar Purkinje cells and nerve triceps brachii was recorded in paralyzed frogs during natural vestibular stimulation. The response from about 63% of the Purkinje cells (mossy fiber input) recorded in the vestibulo cerebellum and of the triceps nerve during triangular wave roll oscillation consisted of activity increase during the ipsilateral side-down half of the cycle and decrease during the contralateral side-down half. It was shown that this activity, which originates partially from ipsilateral vertical canals, can be added to, or suppressed by, otolithic activity, depending on head position and direction rotation. The fact that the response of Purkinje cells was similar to that of triceps nerve implies that the vestibulo-cerebellum receives information of vestibular signals passing to the motor system. The characteristics of otolithic-canal interaction recorded in triceps nerve may explain the motor disturbances that result from lesions of otolithic receptors.

Visual (optokinetic), somesthetic and vestibular inputs to the frog cerebellum.

Unitary response to visual (optokinetic), somesthetic (neck and limb) and vestibular stimulation were recorded from the Purkinje cell layer throughout most of the dorsal surface of the frog cerebellum. Simple spike activity in Purkinje cells and activity from cells without complex spikes were considered. Optokinetic responses (types I-III) were restricted to the dorsal rim and auricular lobes. Units were sensitive to very small velocity of optokinetic cylinder rotation (0.02-0.03 degrees/s) with peak sensitivity at about 1 degree/s. On the average an approximately linear relation of response amplitude to stimulus velocity was observed from 0.02 to 1 degree/s. The response progressively diminished above 1 degree/s to become very small at 30 degrees/s. Asymmetric response and silencing of firing during part of the cycle were nonlinearities observed with sinusoidal optokinetic stimulation in the range of 0.02-1 Hz, +/- 5-10 degrees (peak velocities 0.8-30 degrees/s). Somesthetic responses were recorded throughout most of the corpus cerebelli proper but the strongest input was to rostral regions. No somatotopic arrangement was found. Rather, convergence from more than one limb and neck was relatively common. Adaptation to successive cycles of stimulation was characteristic of somesthetic responses. Vestibular responses (type I-IV) were recorded throughout most of the explored area but the strongest input was to the dorsal rim and auricular lobes. From the analysis of unitary activity, the dorsal rim and auricular lobes are shown to be functionally linked to the vestibular and optokinetic systems whereas the explored part of the corpus is linked to the somesthetic and vestibular systems.

Visual (optokinetic) and somesthetic inputs to the cerebellum of bilaterally labyrinthectomized frogs.

Unitary responses to visual (optokinetic) and somesthetic (cutaneous and propioceptive ) stimulation were recorded from the Purkinje cell layer of the cerebellum of acute (up to 30 h) and chronic (30-90 days) bilaterially labyrinthectomized frogs. Simple spikes from Purkinje cells as well as activity from cells without complex spikes were considered in this paper. The properties of the response and the distribution (restricted to the dorsal rim and auricular lobes) of the units sensitive to optokinetic stimulation of labyrinthectomized frogs, both acute and chronic, were similar to those previously reported for normal animals. The properties of the responses to somesthetic neck and limb stimulation remained similar to those of normal animals. However, there was an increase in the number of units responsive to somesthetic stimulation within the dorsal half of the corpus cerebelli (including the dorsal rim), a region experimentally deprived of vestibular afferents, neck responsive units were 33% of the total in acutely and 61% in chronically labyrinthectomized animals (compared to 5% in normal). Limb responsive units were 49% in acute and 65% in chronic animals (compared to 12% in normal). A consequence of the increase in somesthetic input was convergence of optokinetic and somesthetic inputs at the level of single units within the dorsal rim, totally absent before the lesion. The results suggest that the somesthetic spinal input might substitute for at least some features of the vestibular input to the cerebellum in bilaterally labyrinthectomized frogs.