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Diagnosing a peripheral neuropathy is sometimes challenging, as the causes are diverse and the clinical pictures heterogeneous. Overall, diagnosing a patient with peripheral neuropathy will require some knowledge in almost every field of medicine. Therefore, it appears crucial to adopt a diagnostic strategy that is based on solid clinical and neurophysiological grounds. The present paper describes a three-step diagnostic strategy: (1) to delineate a clinico-pathologic entity from clinical and electrodiagnostic findings; (2) to propose a list of plausible causes based on step one, history and clinical context; (3) to use appropriate workup in order to determine the cause or mechanism of the neuropathy. The three steps of this diagnostic strategy necessitate a high level of expertise and interaction between physicians is highly desirable. Finally, an aggressive course and a severe impairment should lead to relentlessly look for a curable cause., (Copyright © 2017 Société Nationale Française de Médecine Interne (SNFMI). Published by Elsevier SAS. All rights reserved.)

Optical imaging of voltage indicators is a promising approach for detecting the activity of neuronal circuits with high spatial and temporal resolution. In this context, genetically encoded voltage indicators, combining genetic targeting and optical readout of transmembrane voltage, represent a technological breaktrough that will without doubt have a major impact in neuroscience. However, so far the existing genetically encoded voltage indicators lacked the capabilities to detect individual action potentials and fast spike trains in live animals. Here, we present a novel indicator allowing high-fidelity imaging of individual spikes and dentritic voltage dynamics in vivo. Used in combination with optogenetics, which allows to manipulate neuronal activity, this opens the possibility of an all-optical electrophysiology., (© 2016 médecine/sciences – Inserm.)

Background: Classical techniques like endoscopy and esophageal pH-metry are the gold standard to study patients with symptoms related to gastroesophageal reflux disease. Although these techniques have been useful over the years both for diagnosis and therapeutic guidance, there are still many patients with typical or atypical gastroesophageal reflux disease symptoms with normal endoscopy and pH-metry that do not respond adequately to antisecretory therapy. Ambulatory esophageal impedance-pH monitoring is a new technique that can be used to evaluate all types of gastroesophageal reflux, achieving higher rates of sensitivity and specificity than standard techniques., Aim: To precise the technical aspects of the esophageal impedancepH monitoring, indications and results of this technique in clinical practice., Methods: Literature revue of the esophageal impedance - pH monitoring Results: Combined multichannel intraluminal impedance and pH monitoring is a new technique that can be used to evaluate both bolus transport and all types of reflux (acid, weakly acidic and weakly alkaline), without radiation hazards. With this technique, higher rates of sensitivity and specificity than standard techniques are obtained in the diagnosis of pathological gastroesophageal reflux. The technique has also been used in the evaluation of atypical gastroesophageal reflux symptoms, in the assessment of the association of different patterns of reflux with symptoms, and in the evaluation of therapeutic outcome mainly in patients with refractory gastroesophageal reflux disease., Conclusion: The esophageal impedance represents real progress in understanding the different mechanisms involved in the pathophysiology of gastroesophageal reflux. This technique should also allow a better understanding of the responsibility of non-acid reflux in special clinical situations, such as patients resistant to antisecretory or extra-intestinal manifestations of gastroesophageal reflux.

Introduction: Botulism is a rare but serious disease, which affects the peripheral autonomous nervous system, potentially with a fatal outcome. In Morocco, botulism is exceptional., Patients and Method: This was a prospective analysis of the epidemiological, clinical, neurophysiological and toxicological features of 15 cases of food-borne botulism identified among a series of 45 highly suspect cases collected in Morocco during an epidemic in August1999., Results: The 15 patients (eight females, seven males) included in the protocol were aged 3 to 49 years (average 18.8 years). One-third of the cases occurred in a familial context. The clinical presentation was typical and complete in nine cases; respiratory failure was noted in four patients. Botulinum toxins were found in nine cases. Outcome was less than favorable, with total recovery in seven cases, persistence of motor sequelae in three and death in five. Electrophysiological investigations showed an incrementing response at high frequency in 73.3%, a decrement at lower frequency in 60% and low motor amplitudes in 93%. These findings constituted a very sensitive and specific triad for botulism diagnosis., Discussion/conclusion: These findings illustrate the gravity of botulism and the important diagnostic value of neurophysiological results, especially incrementation, which can provide a very pertinent diagnostic contribution, especially in seronegative patients.

A few decades ago, the neuromuscular junction (NMJ) concept was reduced to two elements: the nerve ending and the facing muscular zone. This description has since changed substantially based on recent studies conducted on the molecular aspects of neurotransmission. The aim of this paper is to provide a synthetic view of the major morphological, molecular and electrophysiological tools used in the analysis of NMJ architecture and its functional characterization.

Long lasting polemics about the mechanisms of the action of curare took place at the Société de Biologie over thirty years. After a period during which poisoning protocols were developed on various animal species, where Claude Bernard, Vulpian and their colleagues were involved, German electrophysiology combined its results with new histological data about motor end-plates, elaborating a theory in which young physiologists fought against Claude Bernard's views and finally managed to convince him. According to the new theory proposed by Vulpian, curare blocked transmission between end-plate and muscle. This first draft of the neurotransmission theory helps us to understand the rise of a novel physiology in the context of the school of Claude Bernard with a better integration of disciplines and a more prominent faith in reductionism and materialism.

Multiple white evanescent white dot syndrome (MEWDS) and acute idiopathic blind spot syndrome enlargement (AIBSE) are two acute retinopathies occurring in young patients: improvement is the rule. The present review describes two cases: one case of MEWDS and one of AIBSE. We observed these patients from the acute phase until absolute recovery. Comparing these two reports, we noted differences in ophthalmoscopic, fluorescein angiographics, and multifocal electroretinographic (mERG) analysis, but common findings were observed in clinical presentation and indocyanine green imagery. The first and recent description of these two disorders dates from less than 25 years ago. Although the pathophysiology is still unknown, some authors suggest that these two syndromes could be two different expressions of the same disease, depending on the patient's sensitivity. In our two case reports, multifocal ERG anomalies were directly related to visual impairment and visual field alterations. MEWDS and AIBSE are two acute retinopathies that must be recognized, because of the spontaneous visual recovery that the patient needs to understand for a good follow-up.

Unlabelled: The monitoring of scoliosis treatment can lead to discover its cause., Case Report: A 16-year-old patient was allowed in Center of Functional Rehabilitation for intensive orthopaedic treatment of a severe scoliosis. Electrophysiological explorations carried out within the framework of the monitoring of this treatment detected an axonal neuropathy with sensitive prevalence, whose association with clinical signs made it possible to diagnose Friedreich's disease, then confirmed by molecular biology., Conclusion: Electrophysiological examination is useful in a Rehabilitation Center within the framework of the monitoring of the treatment proposed, more especially as it can make it possible to direct a diagnosis.

Chronic inflammatory demyelinating polyradiculoneuropathy is an autoimmune disease that target myelin sheats of peripheral nerves. Its diagnosis is often difficult to make, and a number of cases are probably not identified because of the clinical and electrophysiological heterogeneity. Typical cases associate progressive or relapsing-remitting motor and sensory deficit with increased CSF protein content and electrophysiological features of demyelination. In some cases electrophysiological studies fail to show evidence of demyelination, conventional electrophysiological diagnostic criteria are not filled yet the patient may respond to immunomodulatory treatments. In such cases, presence of clinical characteristics suggestive of CIDP (that means not compatible with a length-dependent axonal process) are critical justifying fully investigations including sural nerve biopsy. The main clinical characteristic are: a symmetric proximal and distal motor weakness predominantly affecting the lower limbs, a diffuse areflexia, a sensory deficit characterized by a preferential involvement of large fibers, an evolution which may be either chronic progressive or recurrent. Usual therapeutic agents (corticosteroids, intravenous immunoglobulins, plasma exchanges) seem to have the same efficacy whatever the electrophysiologic profile.

There are four basic electrophysiological parameters of demyelination: reduced motor conduction velocity, prolonged distal motor latency and F waves, and motor conduction blocks. These parameters are combined to determine an electrophysiological set of criteria for chronic inflammatory demyelinating polyneuropathy (CIDP). Whereas their specificity is good, their sensitivity level does not exceed 75 percent. However, these sets of criteria are not commonly used especially in benign forms, at the beginning of the disease, in associated forms or in case of secondary axonal degeneration. We can push the limits using others criteria such as the terminal latency index, sensory criteria, or by the contribution of others electrophysiological procedures such as the radicular stimulation or sensory evoked potentials. Due to the therapeutic implications, any axonal neuropathy without aetiologia, with at least one demyelinating electrophysiological criteria, could be considered as a putative CIDP.

Coronary artery disease is still a major cause of morbidity and mortality in the industrialized countries and its prevalence is predicted to grow with the current aging of the population in these countries. In spite of the rapid pace of progress and increasing use of myocardial revascularization procedures, in particular percutaneous coronary interventions, the medical treatment of coronary artery disease has lost none of its relevance in the majority of patients, though conventional drugs have their limitations and the pharmacological approach to ischemic heart disease needs to be improved in terms of efficacy and tolerance to ensure better prevention of mortality and improvement in quality of life. Since increased heart rate plays a major role in coronary artery disease, not only as a trigger of most ischemic episodes, but also as an independent predictor of mortality, inhibition of the pacemaker If current in view of inducing a direct and selective decrease in heart rate represents an ideal conceptual target and an attractive therapeutic approach to coronary artery disease. The screening of original benzocycloalkane compounds at the Servier Research Institute resulted in the selection of ivabradine (Procoralan) for clinical development. Preclinical data showed that ivabradine inhibits the If current originating in the sinus node, induces a selective reduction in heart rate both at rest and during exercise, preserves myocardial contractility, atrioventricular conduction and ventricular repolarization and prevents exercise-induced myocardial ischemia as effectively as a b-blocker while offering better protection of regional myocardial contractility. These data were confirmed in humans, in particular the anti-ischemic efficacy of ivabradine, at least as effective as that of a b-blocker in patients with stable angina. Large ongoing clinical trials are seeking to assess the therapeutic value of ivabradine in ischemic heart failure and its potential for improving the prognosis of coronary artery disease by reducing mortality and the occurrence of major cardiovascular events.

Defined more than one century ago, the concept of positive symptoms has become obsolete, except in the psychiatric domain. However, its relevance remains intact today when considering such pathophysiologies as neuropathic (phantom) pain, movement disorders, tinnitus, epilepsy, and psychiatric disorders. Beside their very different clinical characteristics, all these symptoms arise from a lesion in the nervous system. Furthermore, they are paradoxical in the sense that they correspond to a spontaneous hyperactivity of the injured functional system, concomitant to the usual deficits resulting from the lesion. Could these similarities reflect the existence of some common pathophysiological process? A peculiar electrophysiological property of thalamic cells is likely to be compatible with this hypothesis. A thalamic cell produces action potentials when depolarised by excitatory inputs. Conversely, its ability to produce action potentials is decreased or even completely suppressed when the same cell is hyperpolarized by inhibitory influences. However, depending on its level of hyperpolarization, this cell can also produce rhythmic paradoxical bursts of activity at low frequency (3-4 Hz). In this context, a lesion involving, for example, the somatosensory excitatory fibres gives rise to hyperpolarization of the corresponding thalamic cells, which may produce such rhythmic bursting activity. This causes an increase of low frequency thalamo-cortical activity, which, through reduction of collateral cortico-cortical inhibition, induces high frequency activity in neighbouring thalamo-cortical loops ("edge effect"). This leads to the appearance of the clinical symptoms, in this case, pain. Electrophysiological recordings performed in patients suffering from sensory or motor positive symptoms have shown the presence of such deleterious sequence of events. Furthermore, the efficiency of neurosurgical treatments that are used against some positive symptoms can be explained on the basis of such a dynamic process. Both considerations support the validity of the proposed hypothesis and open avenues for the control of other positive symptoms.

Electrophysiological investigations of cranial nerves have long been limited to conventional electromyography, but recently have undergone new developments. Brainstem reflex testing is now well defined with correlations to imaging data. Brainstem reflexes can be tested in trigeminal and facial nerve diseases, but also in the case of intra-axial lesions. Surface neurography has developed to quantify troncular nerve responses, abnormal facial nerve responses or assessment of neuromuscular junction function through repetitive stimulation. Transcranial magnetic or electrical stimulation allows to functionnally investigate proximal cranial nerve segments as well as central pathways. Intra-operative monitoring of various cranial nerves can be useful but techniques still need to be validated. Therapeutic use of botulinum toxin involves the electromyographist, as well for the diagnosis as for EMG-guided injections.

The Chronic Inflammatory Demyelinating Polyradiculoneuropathies (CIDP) constitute a syndrome whose incidence is difficult to evaluate, and is probably underestimated. In the course of this presentation, we deliberately restricted discussion to issues raised in recent years concerning the extent of this syndrome. We discuss diagnostic criteria, especially electrophysiological ones. As the criteria proposed by the ad hoc committee of the American Academy of Neurology in 1991 have been questioned due to lack of sensitivity, new ones have been proposed recently. We briefly discuss the different types of chronic dysimmune demyelinating neuropathy: not only the CIDP, but also the Lewis and Sumner syndrome or multifocal inflammatory demyelinating neuropathy and the multiple conduction block neuropathies. At last, we point out the consistent finding of axonal involvement in the course of a chronic demyelinating neuropathy; over time, it can become pre-dominant, which may make diagnosis difficult by suggesting a chronic axonal neuropathy that may be assumed to be primary. Consideration of these points may help clinicians recognize more chronic dysimmune neuropathies, for which immunosuppressive therapy has been found to be effective.

Purpose: To document the progression of clinical and electrophysiological abnormalities in an infant with carbohydrate-deficient glycoprotein syndrome type Ia (CDGS Ia) over a period of 5 years., Patient and Methods: A 12-month-old male underwent clinical ophthalmic and electrophysiological examination at the age of 1, 2, and 6 years. Neurological examination, magnetic resonance imaging of the brain and a genetic study were also undertaken., Results: Clinical examination revealed hypotonia and ataxia with a convergent squint, nystagmus, myopia with pontocerebellar hypoplasia on the MRI of the brain. The initial electroretinogram showed reduced amplitude of the scotopic and photopic b wave. At 3 years of age, biological and genetic evaluations confirmed the diagnosis of CDGS Ia. At 6 years of age, the electroretinogram was flat with a marked delay in psychomotor development., Conclusion: Carbohydrate-deficient glycoprotein syndrome type Ia is a recently described cause of progressive retinal degeneration and an electroretinogram should be taken in patients with psychomotor retardation of unknown etiology. In addition, strabismus associated with electrophysiological signs of anomaly should raise the possibility of CDGS Ia.

Fulguration, a widely used technique in the 80s, has been replaced by radiofrequency ablation. The limited and better controlled intra-cardiac lesions obtained by this method allowed the elimination of a large number of tachycardias with a high success rate. However, there are many arrhythmias, particularly at the atrial level, which are so complex that a limited analysis at a number of points of endocardial recording is inadequate. Recently, a number of systems has been introduced which considerably increased the acuity of observation of arrhythmias and the efficacy of their ablation. First of all, there are improved techniques of classical electrophysiological recording. Then, new systems of temporo-spatial recordings were developed and are described in this article. These use computer systems and enable particularly reliable and detailed approaches to cardiac anatomy and electrophysiology. However, the optimal use of these techniques can only be in specialised centres, by highly trained cardiologists in classical electrophysiology, for which they are complementary to rather than substitute for.

A 42-year-old man was affected with multiple cerebral lesions suggesting expanding lacunae. He had suffered for about 15 years of headaches and blurred vision. Neurological examination showed a Parinaud syndrome and a skew deviation. Magnetic resonance imaging showed an enlargement of the third and lateral ventricles and multiple intraparenchymatous lesions with a signal similar to that of the cerebrospinal fluid. These lesions were located in the mesencephalon and right thalamic region. Important discrepancies between the topography of the lesion and the clinical data were observed. Neurological examination, ocular movements during wake and neuropsychological testing suggested sub-cortical dysfunction. These results suggest functional rather than lesional repercussion of expansive lacunae.

Sexual disorders may be assessed in diabetic patients with neurophysiological investigations of the perineum including electromyographic detection of perineal floor muscles, sacral latency, somatosensory evoked potentials of the pudendal nerve, sympathetic skin response and nerve conduction velocity of the dorsal nerve of the penis. Alteration of sympathetic skin response and sensory dysfunction (reduction of the velocity or reduction in the amplitude of the distal sensory potential, alteration of the pudendal cortical evoked potentials) are the more frequent signs of perineal diabetic neuropathy.

A range of diagnostic investigations and threshold values were evaluated prospectively in 100 cases of symptomatic carpal tunnel syndrome in 60 patients. Proportions of cases with abnormal findings were 44/100 for the needle study, 56/100 for distal motor latency, 65/100 for digit-to-wrist orthodromic sensory conduction velocity, and 78/100 for palm-to-wrist orthodromic sensory conduction velocity. Among the 22 patients who had normal findings for these conventional parameters, 5 had a double peak after global fourth digit stimulation, 20 had a fourth digit median-ulnar latency difference of 0.40 msec or more, and 22 had an abnormal centimetric test. These data highlight the value of palm-to-wrist orthodromic sensory conduction velocity measurements among routine tests, of fourth digit median-ulnar latency difference measurement among sophisticated nonroutine tests, and of the centimetric test as the gold standard for the diagnosis of carpal tunnel syndrome.

A new gustatory clinical test and its normative approach are presented. The measure's coherence seems to be better with salt and sweet stimuli than with bitter ones.

15 COPD patients underwent a polysomnographic study demonstrating poor quality of sleep, a mean of SAO2 of 88.8 +/- 3.9% and a apneic-hypopnea index (AHI) of 5.7 +/- 11.8. AHI was higher in sleep stages I and II than in REM sleep. SAO2 showed a progressive drop when going from an awake stage to REM sleep. Respiratory events responsible for the most important desaturation where mostly observed in REM sleep and corresponded in 8 patients to obstructive events (overlap syndrome). The lower mean SAO2 in REM probably explains the best the importance in desaturation related to the respiratory events (Hb dissociation curve). Ear oximetry recordings however interesting are not able to quantify and recognise correctly the respiratory events. Therefore a polysomnographic study remains necessary in order to diagnose adequately the overlap syndrome.

The aim of this study was to assess the effect of delayed release Disopyramide 500 mg daily on sinus node function in 12 subjects with sinus node dysfunction and supraventricular and/or ventricular excitability. An ECG, Holter monitoring and electrophysiological studies of sinus node function with an oesophageal electrode were performed before and after 5 days treatment. The drug had to be discontinued in 1 patient because of urinary retention. The Disopyramide suppressed the clinical tachyarrhythmias in 8 out of the 11 subjects. The maximal sinus pause observed on Holter monitoring did not change significantly. It only increased in one subject. The mean sinus cycle length during electrophysiological study slightly decreased but there was a global increase in sinoatrial conduction time from 309 +/- 164 to 413 +/- 125 msec and of the corrected sinus mode recovery time from 470 +/- 168 to 605 +/- 303 msec. However, these changes were not significant. This study of delayed released Disopyramide shows a discordance between the tendency for sinus node function to deteriorate when assessed by electrophysiological studies and good clinical tolerance as assessed by Holter monitoring in the bradycardia-tachycardia syndrome.

Parasympathetic and sympathetic pathways may be assessed by using different electrophysiologic tests. Sympathetic skin potentials (SSP) are elicited with peripheral electrical stimulation (e.g. median nerve or pudendal nerve). SSP are recorded from the skin of the hand and foot and from the genital skin. Skin responses were always obtained from normal volunteers. Absence of SSP is one of the earliest findings in neurogenic impotence. Electromyography of corpora cavernosa is described with a new method. A new corpora cavernosa response to pudendal nerve stimulation is described. This test appear to have application in the evaluation of neurogenic impotence.

The roles of Holter monitoring and electrophysiological studies (EPS) in the evaluation of antiarrhythmic drugs for ventricular arrhythmias are to record their effects on ventricular extrasystoles (VES) and ventricular tachycardia (VT), and to search for undesirable rhythmological effects. The usual protocol is to perform baseline studies and then repeat them after a certain period of treatment using a number of modalities, comparison with placebo, control group, in acute or oral administration. Holter monitoring is an economical non-invasive method which carries no risk. Spontaneous arrhythmias of sufficient frequency to be recorded during the monitoring period can be studied. When applied to VES, it provides quantitative rather than qualitative information despite classifications such as Lown's. The results should be analysed taking spontaneous variations of the arrhythmia into consideration. Holter monitoring may also reveal proarrhythmic drug effects (bradycardia, torsades de pointe). However, there are no absolute criteria of efficacy except total suppression of VES, unexplainable by spontaneous variability. Holter antiarrhythmic studies require stable VES which creates a bias in the evaluation of results due to the special selection of patients. Electrophysiological studies are costly, invasive and uncomfortable but they are the only way of assessing paroxysmal VT apart from clinical follow-up. This method is only applicable to inducible VT, which is the commonest form. The investigating protocols are specific and reproducible: a tachycardia which is non-inducible does not recur in 90% of cases, which enables prediction of the antiarrhythmic effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrophysiological techniques have significantly improved in the last decade. The authors present a short list of the available current techniques.

Electrophysiologic studies are used for diagnosis and treatment in patients with sustained ventricular tachycardia. This method can only be employed if high inducibility of the spontaneous tachycardia can be demonstrated. We therefore investigated prospectively the induction yield in 35 patients with a history of documented sustained ventricular tachycardia. The patients' mean age was 58 years. Coronary artery disease was present in 24 patients, cardiomyopathy in 4, other organic heart diseases in 4, and no heart disease in 3. The ventricular tachycardia induction protocol consisted of three extrastimuli delivered during sinus rhythm and at two pacing cycle lengths, followed by intravenous isoproterenol if no tachycardia was induced before. With the method sustained ventricular tachycardia was induced in 100% of patients with coronary artery disease and cardiomyopathy, in 75% of patients with other heart diseases and in 33% of patients without detectable heart disease. We conclude that electrophysiologic studies have a high yield of sustained ventricular tachycardia induction in patients with underlying organic heart disease. The rational basis for use of electropharmacologic testing therefore exists in these patients. However, in patients without heart disease, the low sensitivity of electrophysiologic studies precludes its use for drug efficacy testing.

Holter electrocardiographic monitoring and endocavitary electrophysiological investigations are often necessary in order to confirm the diagnosis of sinus dysfunction which may be suggested by the patient's symptoms and/or standard E.C.G. signs. A critical evaluation of these methods can be made on the basis of the experience gained in the course of recent studies. Provided sufficiently rigorous criteria are selected, the Holter monitor has an excellent specificity, about 90%, and a sensitivity of more than 70%. The value of the sinus refractory period reflects both sinus automatism and sino-atrial conduction; it is a sensitive criterion of sinus dysfunction. In contrast, the period of sino-atrial conduction has a much more limited sensitivity. However, analysis of the various parameters which reflect the response of the sino-atrial node to premature atrial stimulation provides important information. The authors also stress the value of the pharmacological tests used to sensitize the manoeuvres of atrial stimulation or to test the effects of the autonomic nervous system on sinus function. Autonomic blocking with a combination of atropine and propranolol can reveal certain disorders which can be masked by sympathetic activity and it can also determine the intrinsic or extrinsic nature of the sinus dysfunction. Thus electrophysiological investigations appear to be often essential in order to confirm a suspected diagnosis and in order to determine the severity and the nature of the sinus dysfunction.

The purpose of this article is to present a new electrophysiological evaluation method to study facial nerve function. This technique studies the afferent sensory pathways and the efferent motor fibres. The study of the various parameters of those two functions allows us to draw certain conclusions relating to the prognosis and localization of facial nerve lesions.

Technique of long-term recording from single neurons in brain of freely moving animals with floating mobile microelectrodes.

1 A method is described for on line separation and classification of individual action potentials from multi unit extracellular recordings from intact nerves. 2 this method is based on the simultaneous determination of several of the features of each action potential, especially their form and velocity. 3 provided that only a few conditions are fulfilled, each of the action potentials can be recognized, and the recognition work is achieved at the time of the generation of the action potentials. 4 The prerequisite conditions are the following: the nerve diameter should not exceed a few tenths of a millimeter. The nervous filament must be carefully dissected from the surrounding tissue. The overall frequency of the action potentials should not exceed 1000 spikes/sec.

Unitary recordings of spontaneous activity were performed from vestibular ganglion perikaria and axons of Mouse inner ear explants. The latter were from 1-11 day postnatal mice and were maintained in vitro at 37 degrees C, in a defined bathing medium. Spontaneous action potentials were obtained at each developmental stage and presented the distinctive features of the in vivo recorded activities during normal development. On the 3rd day post partum the recorded activities were of the immature type, with slow irregular discharge frequencies. In ganglia 3 to 9 days post partum the spike frequencies increased and the discharges exhibited 3 distinct firing patterns. This electrophysiological maturation of vestibular receptors is discussed in comparison with the morphological maturation of the vestibular organ during the same postnatal period.