Sudden Loud Noise Research Articles

Behavioral responses of free-ranging Japanese macaques (Macaca fuscata) to sudden loud noises.

We opportunistically observed 31 cases of responses to sudden loud noises mainly caused by falling rocks and trees in a free-ranging, provisioned group of Japanese macaques, Macaca fuscata, at Katsuyama, Japan, and analyzed 27 cases for which we successfully recorded their responses. In 88% of the 24 cases in which the highest- or second-highest ranking adult male probably heard the noise, one or both of them vocalized aggressively in response. Other males tended to vocalize when they were far away from the two highest-ranking males (in 5 of 7 cases in which they vocalized). Adult females vocalized in only 8% of cases, even when they fled from the noise source. These findings suggest that, unlike tree-shaking and female-directed aggression- both performed often in the mating season and accompanied by vocalizations in both high- and low-ranking males of Japanese macaques- vocalizing in response to sudden loud noises is usually limited to one or two high-ranking males in the vicinity. This vocal response could be a way for the males to advertise their social status; it may also serve to calm group members scared by the noise, preventing them from fleeing in panic and dispersing widely. Our observations also suggest that males may monitor which other males remain nearby, and that whereas females may scream in response to socially induced fear, they are least likely to do so in response to fear arising from non-social contexts.

Exploding Head Syndrome among Patients Seeking Help for Tinnitus and/or Hyperacusis at an Audiology Department in the UK: A Preliminary Study.

Exploding head syndrome (EHS) is characterized by hearing a sudden loud noise or experiencing a sense of explosion in head during the transition of sleep-wake or wake-sleep. The experience of EHS shares similarities with tinnitus, where an individual perceives a sound without any external sound source. To the authors' knowledge, the possible relationship between EHS and tinnitus has not been explored. Preliminary assessment of prevalence of EHS and its related factors among patients seeking help for tinnitus and/or hyperacusis. Retrospective cross-sectional study. A total of 148 consecutive patients who sought help for tinnitus and/or hyperacusis at an audiology clinic in the United Kingdom. The data regarding demographics, medical history, audiological measures, and self-report questionnaires were collected retrospectively from the patients' records. Audiological measures comprised of pure-tone audiometry and uncomfortable loudness levels. The self-report questionnaires which were administered as a part of standard care comprised of the Tinnitus Handicap Inventory, numeric rating scale of tinnitus loudness, annoyance, and effect on life, hyperacusis questionnaire, Insomnia Severity Index, Generalized Anxiety Disorder scale 7, and Patient Health Questionnaire (PHQ-9). To establish presence of EHS, participants were asked "Do you ever hear a sudden, loud noise, or feel a sense of explosion in your head at night?" EHS was reported by 8.1% of patients with tinnitus and/or hyperacusis (12 out of 148). The patients with and without EHS were compared, but no significant relationships were found, between the presence of EHS and age, gender, tinnitus/hyperacusis distress, symptoms of anxiety or depression, sleep difficulties, or audiological measures. The prevalence of EHS in a tinnitus and hyperacusis population is similar to that in the general population. While there does not seem to be any association with sleep or mental factors, this might be due to the limited variability in our clinical sample (i.e., most patients exhibited high level of distress regardless of EHS). Replication of the results in a larger sample with more variety of symptom severity is warranted.

Exploding Head Syndrome Associated With Severe Obstructive Sleep Apnea

Exploding head syndrome (EHS) is characterized by a sudden loud noise or sense of explosion in the head at the wake-sleep transition or upon waking during the night. In many cases, its symptoms tend to disappear spontaneously without requiring treatment. Some studies have suggested an association between EHS and obstructive sleep apnea. Here I present an elderly man having an intermittent sense of lightning with a little sound in his head during sleep. Polysomnographic evaluation revealed hypopnea preceding his habitual symptom. EHS symptoms decreased by positional therapy with weight reduction. They nearly disappeared after auto-adjusting positive airway pressure therapy.

Genetic parameters for noise reactivity in standard poodles

The aim of this study was to increase knowledge on the genetic background of noise reactivity in dogs, with a study on heritability based on owner-collected data on standard poodles’ degree of fear of sudden loud noises and fireworks. Previous studies have shown significant breed differences, and we expected to find significant heritability for noise reactivity. 1148 standard poodles are included in the study. The estimated heritabilities are between 0.09 and 0.16. Reaction to sudden loud noises and fireworks are genetically highly correlated (rg > 0.95).

Phosphorylation of Gephyrin in Zebrafish Mauthner Cells Governs Glycine Receptor Clustering and Behavioral Desensitization to Sound.

The process by which future behavioral responses are shaped by past experiences is one of the central questions in neuroscience. To gain insight into this process at the molecular and cellular levels, we have applied zebrafish larvae to explore behavioral desensitization to sound. A sudden loud noise often evokes a defensive response known as the acoustic startle response (ASR), which is triggered by firing Mauthner cells in teleosts and amphibians. The probability of evoking ASR by suprathreshold sound is reduced after exposure to repetitive auditory stimuli insufficient in amplitude to evoke the ASR (subthreshold). Although it has been suggested that the potentiation of inhibitory glycinergic inputs into Mauthner cell is involved in this desensitization of the ASR, the molecular basis for the potentiation of glycinergic transmission has been unclear. Through the in vivo monitoring of fluorescently-tagged glycine receptors (GlyRs), we here showed that behavioral desensitization to sound in zebrafish is governed by GlyR clustering in Mauthner cells. We further revealed that CaMKII-dependent phosphorylation of the scaffolding protein gephyrin at serine 325 promoted the synaptic accumulation of GlyR on Mauthner neurons through the enhancement of the gephyrin-GlyR binding, which was indispensable for and could induce desensitization of the ASR. Our study demonstrates an essential molecular and cellular basis of sound-induced receptor dynamics and thus of behavioral desensitization to sound.SIGNIFICANCE STATEMENT Behavioral desensitization in the acoustic startle response of fish is known to involve the potentiation of inhibitory glycinergic input to the Mauthner cell, which is a command neuron for the acoustic startle response. However, the molecular and cellular basis for this potentiation has been unknown. Here we show that an increase in glycine receptor (GlyR) clustering at synaptic sites on zebrafish Mauthner cells is indispensable for and could induce desensitization. Furthermore, we demonstrate that CaMKII-mediated phosphorylation of the scaffolding protein gephyrin promotes GlyR clustering by increasing the binding between the β-loop of GlyRs and gephyrin. Thus, the phosphorylation of gephyrin is a key event which accounts for the potentiation of inhibitory glycinergic inputs observed during sound-evoked behavioral desensitization.

Glycine Transporter 1 Encephalopathy From Biochemical Pathway to Clinical Disease: Review.

Glycine transporter 1 encephalopathy (OMIM# 617301; glycine encephalopathy with normal serum glycine, GLYT1 transporter dysfunction, and nonketotic hyperglycinemia) is caused by mutations in the SLC6A9 gene. To date, 6 cases have been reported in the literature, characterized as having neonatal onset, respiratory failure that required mechanical ventilation, severe hypotonia at birth that progressed to limb hypertonicity, and startle-like responses provoked by sudden loud noises and tactile stimulation. Additional characteristics included dysmorphic features, musculoskeletal abnormalities, and abnormal antenatal findings. Initial diagnosis include elevated levels of glycine in cerebrospinal fluid and an elevated cerebrospinal fluid to plasma glycine ratio. Abnormal magnetic resonance imaging findings included white matter abnormalities, thin corpus callosum, dilatation of the lateral and third ventricles, caudate atrophy, and tiny cysts. Patients reported so far showed normal electroencephalogram results. Treatment was supportive and appeared severe as 50% of the patients died between 2 days and 7 months of age, while surviving children had global developmental delay. In this report, we reviewed the published cases having glycine transporter 1 encephalopathy and retrospectively characterizing the disease phenotypes, affected biochemical pathways, neuroradiological abnormalities, diagnosis, genetic issues, and treatment; additionally, key discussion points are also presented.

0736 POLYSOMNOGRAHIC FINDINGS IN FIVE PATIENTS WITH EXPLODING HEAD SYNDROME

Exploding Head Syndrome (EHS) attacks are characterized by perception of sudden loud banging noises, occasionally accompanied by the sensation of a flash of light. Although these attacks themselves are usually not painful, it is reported that EHS attacks may precede migraine as auras. EHS is classified as a type of parasomnia in the International Classification of Sleep Disorders (ICSD) 3rd edition and its pathophysiology is still unclear. We describe the polysomnography (PSG) characteristics of EHS patients with special emphasis on respiratory events that were followed by EHS attacks. The subjects were consecutive 20,926 patients who presented sleep and/or wake problems at our sleep center between April 1998 and March 2013. The diagnosis of EHS was based on ICSD-3 criteria. During PSG, we instructed them to ring a bell when they noticed an attack (heard a sound). We found 5 cases (0.17%) with EHS. The mean age (2 men and 3 women) was 64.8 ± 16.4 years. Three of them had otorhinolaryngologic diseases (sudden hearing loss, deflected nasal septum and sinusitis). All five subjects rang the bell for their attacks during PSG. The events occurred during stage N1 and N2. In 2 cases, respiratory events preceded the attacks. In 1 case, respiratory effort related arousal was followed by the attack. In the other 2 cases snoring preceded the attacks. One subject noticed the attack during stage W. Various respiratory events were related to the EHS attacks. A variety of ear dysfunctions or brainstem neural dysfunction during the transition from wakefulness to sleep has been reported as the pathophysiology of EHS. Our PSG findings suggest that checking otolaryngological status on subjects and respiratory events during sleep may be helpful in understanding its pathophysiology and in choosing therapeutic strategies. None.

Pharmacological agents used for treatment and prevention in noise-induced hearing loss.

Noise is a stress factor that causes auditory, psychological and physiological effects. The realization that sudden loud noises or chronic exposure to noise in social and working environments can cause hearing loss has led to increased interest in noise-induced hearing loss (NIHL). The best means of preventing primary damage is protection against noise. Since this protection is not always possible for various reasons, the use of pharmacological agents to prevent or treat NIHL should also be considered. The purpose of this study is to discuss current pharmacological protection and treatment options in the light of the literature, since no such extensive reviews have been performed to date, including agents used for protection against and treatment of NIHL. We reviewed both animal and clinical studies, and these are discussed separately for ease of comprehension. For each agent, first animal studies, then clinical studies, if available, are discussed. We also performed a two-step search of the literature. In the first step, we searched the terms "noise induced hearing loss", "treatment" and "protection" in Pubmed. Based on the results obtained, we identified the agents used for the treatment of and protection against NIHL. In the second step, we searched the names of the agents identified in the first step, together with the term "noise induced hearing loss," and reviewed the results.

Brainstem auditory evoked potential findings in a French bulldog with bilaterally congenital sensorineural deafness

Abstract : A 3-month-old, intact male French bulldog was suspected of deafness. The dog was irresponsive toenvironmental noises generated out of sight, but normal responses were noted for visual stimuli. No abnormalitieswere observed on the neurological, otoscopic, radiographic, and blood examinations. To diagnose the apparent deafness,brainstem auditory evoked potential (BAEP) was recorded in the presented dog together with a normal dog. Whilethe BAEP from the control dog showed a normal wave consisting of 5 peaks, absence of all peaks was noted inthe suspected deaf dog. Therefore the dog was definitively diagnosed as bilaterally congenital sensorineural deafness.Keywords : brainstem auditory evoked potential, congenital sensorineural deafness, French bulldog In recent decades, the occurrence of congenital deafnesshas been increased in dogs relative to the increased aware-ness among breeders, owners and clinicians [13]. Generally,auditory function is necessary for avoiding traffic accidentand other danger incidence. Because deaf dogs are easily sur-prised and have an increased tendency to bite, they are hardlysuitable for use as working. Therefore the puppy with bilat-eral deafness needs to be trained by a responsible owner, butthis kind of training is difficult and unfamiliar. By these rea-sons, bilaterally deaf puppies are easily euthanized [7].If the proper diagnosis of hearing impairment could bedone in dogs, especially working breeds, it will decrease costand efforts for being needed in training. Bilateral deafnesscould be evaluated by monitoring behavioral responses forsound stimuli presented outside of the visual field or with theanimal blindfolded, taking care to avoid visual or vibratorycues [11]. However, behavioral testing is often unreliable andsubjective [1]. Therefore several objective methods, includ-ing electroaudiomerty-encephalographic, audiometry, respira-tory audiometry, tympanometry, auditory evoked responses,and acoustic reflexes, have been used for diagnosing audio-logical or otological disorders in veterinary medicine [10].Among those methods, the brainstem auditory evoked poten-tial (BAEP) has been proven to be the most objective andnon-invasive assessment of auditory function [14, 15]. There-fore the BAEP is frequently used as a screening test for deaf-ness. Previously congenital deafness had been recognized inFrench bulldog, but the BAEP finding has not been reportedin this breed [11, 13]. Therefore this report firstly describesthe clinical and diagnostic features of bilaterally congenitalsensorineural deafness (CSD) in a French bulldog using theBAEP.A 3-month-old, intact male French bulldog was presentedwith suspected deafness. This dog was the youngest onefrom 4 literamates, and the other 3 littermates had no hear-ing disabilities or other diseases. The owner had not observedany response of the dog for sound stimuli since 1 month agoadoption. There was no history of exposure to any causes ofdeafness; illness, head trauma or ototoxic drugs. Physicalexamination revealed mild erythema on the bilateral earpinna and epidermal collarettes on the abdomen. Its coatcolor was predominantly white and black, especially whiteareas presented on the ventral thorax, abdomen, feet, foreleg,and head. On behavior testing, the dog was irresponsive toenvironmental noises generated out of sight, but normalresponses were noted for visual stimuli. Any startle responseswere not elicited to sudden loud noises. Bilaterally, intacttympanic membranes and the grossly normal external earcanals were observed on the otoscopic examination. Thetympanic bulla was examined by radiography with differentviews of the open mouth dorsolateral, lateral-oblique, androstrocaudal projections. Those radiographic studies revealednormal bone density and no fluid density or diminution offoraminal detail within the tympanic bulla. In addition,

Teaching Neuro Images : PET-CT hypermetabolism paralleling muscle hyperactivity in stiff-person syndrome

A 72-year-old woman with autoimmune hypothyroidism and type 1 diabetes mellitus presented with 1 year of progressively worsening neck, back, and right thigh spasms and leg stiffness. Sudden loud noises would startle her. She ambulated with a walking frame. Serum glutamic acid decarboxylase 65 antibody was markedly elevated (1,118 nmol/L; normal value ≤0.02 nmol/L). EMG demonstrated poor relaxation in thoracic paraspinal muscles and right quadriceps and failure of the acoustic startle response to habituate consistent with stiff-person syndrome.1,2 Whole-body PET-CT imaging, performed to exclude malignancy, demonstrated increased fluorodeoxyglucose metabolism in axial and proximal lower extremity regions that paralleled the clinically most hyperactive muscle groups (figure, A and B). No malignancy was detected.

Critical phase distractions in anaesthesia and the sterile cockpit concept

In aviation, the sterile cockpit rule prohibits non-essential activities during critical phases of flight, takeoff and landing, phases analogous to induction of, and emergence from, anaesthesia. We studied distraction during 30 anaesthetic inductions, maintenances and emergences. Mean (SD) noise during emergence (58.3 (6.2) dB) was higher than during induction (46.4 (4.3) dB) and maintenance (52 (4.5) dB; p<0.001). Sudden loud noises, greater than 70 dB, occurred more frequently at emergence (occurring 34 times) than at induction (occurring nine times) or maintenance (occurring 13 times). The median (IQR [range]) of staff entrances or exits were 0 (0-2 [0-7]), 6 (3-10 [1-18]) and 10 (5-12 [1-20]) for induction, maintenance and emergence, respectively (p<0.001). Conversations unrelated to the procedure occurred in 28/30 (93%) emergences. These data demonstrate increased distraction during emergence compared with other phases of anaesthesia. Recognising and minimising distraction should improve patient safety. Applying aviation's sterile cockpit rule may be a useful addition to our clinical practice.

Increased Auditory Startle Reflex in Children with Functional Abdominal Pain

To test the hypothesis that children with abdominal pain-related functional gastrointestinal disorders have a general hypersensitivity for sensory stimuli. Auditory startle reflexes were assessed in 20 children classified according to Rome III classifications of abdominal pain-related functional gastrointestinal disorders (13 irritable bowel syndrome [IBS], 7 functional abdominal pain syndrome; mean age, 12.4 years; 15 girls) and 23 control subjects (14 girls; mean age, 12.3 years) using a case-control design. The activity of 6 left-sided muscles and the sympathetic skin response were obtained by an electromyogram. We presented sudden loud noises to the subjects through headphones. Both the combined response of 6 muscles and the blink response proved to be significantly increased in patients with abdominal pain compared with control subjects. A significant increase of the sympathetic skin response was not found. Comorbid anxiety disorders (8 patients with abdominal pain) or Rome III subclassification did not significantly affect these results. This study demonstrates an objective hyperresponsivity to nongastrointestinal stimuli. Children with abdominal pain-related functional gastrointestinal disorders may have a generalized hypersensitivity of the central nervous system.

Exploding head syndrome – More than “snapping of the brain”?

Fig. 1. 54-year-old patient holding his head six seconds after waking up from NREM2 sleep (during MSLT) due to an EHS attack. Exploding head syndrome (EHS) is a rare benign sleep-wake transition disorder of unknown aetiology and was first described in 1920 as a ‘‘snapping of the brain’’ [1]. EHS attacks are characterized by sudden loud banging noises ‘‘bomb-like explosions’’ or ‘‘shotgun’’ and in 10–20% of patients are accompanied by the sensation of ‘‘flashing lights’’. These attacks are not painful but are unpleasant and sometimes even terrifying to the patients, often raising concerns that an acute subarachnoid haemorrhage may have occurred. EHS attacks occur in relaxed wakefulness or at the transition from wakefulness to sleep and can vary in frequency [2]. Video-documentation of EHS attacks is to our best knowledge not available to the medical community so far. We present the unusual case of a 54-year-oldmale with a three-year history of sudden ‘‘attacks of an exploding head’’, who consistently reported on an exacerbation of his chronic migraine with each EHS attack. Attacks occurred every two hours in the daytime and about two times at night. On video polysomnography (PSG) and multiple sleep latency test (MSLT), EHS attacks evolved at the transition fromwakefulness to sleep (non-rapid eye movement [NREM] sleep stage 1, NREM1) and from NREM2 with an impressing characteristic (see Fig. 1 and video). Abrupt movement artefacts but no epileptic discharges were recorded during these attacks. Togetherwith a recent report ofmigraine aura presenting as EHS [3] our case suggests that EHS may represent

Prepulse inhibition of acoustic startle response in mild cognitive impairment and mild dementia of Alzheimer type

Amnestic mild cognitive impairment (MCI) describes the condition of memory-impaired individuals who otherwise function well and do not meet the clinical criteria for dementia. Such individuals are considered to represent a transitional stage between normal aging and dementia of Alzheimer type (DAT). Neurobiologic changes in amnestic MCI, and their significance for psychophysiologic function, are poorly understood. In this study, the authors compared acoustic prepulse inhibition (PPI) between subjects with amnestic MCI and mild DAT to characterize sensorimotor gating. The acoustic startle reflex, which the authors measured using an accelerometer and electromyogram, involves whole-body movement and eye blink in response to a sudden loud noise (115 dB). PPI is inhibition of this reflex by a softer noise (prepulse; 85 dB) preceding the startle stimulus by 30 ms. PPI was examined in 30 controls, 20 subjects with amnestic MCI, and 20 subjects with mild DAT. Neither amnestic MCI nor mild DAT affected startle movement amplitude. Subjects with amnestic MCI showed significantly enhanced PPI (gating facilitation), while subjects with mild DAT exhibited significantly less PPI than controls (gating deficit). This pattern of PPI changes suggests that neuropathologic changes in the limbic cortex, mainly the entorhinal cortex, at the earliest stage of DAT might be responsible for PPI abnormalities via disturbed regulation of the limbic cortico-striato-pallido-pontine circuitry. Startle PPI changes could be used as a biologic marker for amnestic MCI and mild DAT.

The Long-QT Syndrome

The heart is a pump that is stimulated by electrical signals to beat between about 50 to 180 times per minute, depending upon the individual’s level of activity and emotional state. The heart itself is made up of millions of cells that generate repetitive sequences of electrical discharges (referred to in medicine as depolarization) and recharging (repolarization) that produce each heart beat. Electrical activity of the heart cells is produced by the synchronized movement of sodium, potassium, and calcium ions into and out of the cells. ### Long-QT Syndrome Long-QT Syndrome (LQTS) is a disorder of the electrical activity of the heart that can result in blackouts (fainting, also known as syncope) or sudden cardiac death. It occurs infrequently and is caused either by an inherited genetic condition (inherited form of LQTS) or by some prescription medications (acquired form of LQTS). QT refers to the interval on ECG between the beginning of the heart’s electrical discharge through its electrical recovery (see Figure 1). Figure 1 illustrates how the QT interval is measured on the ECG. Schematic diagram of the electrical activity of one heart beat recorded by an ECG. The electrical discharge (depolarization) of the ventricle is represented by the QRS complex, with the T wave reflecting electrical recovery (repolarization). The QT is the time interval from the beginning of the QRS complex to the end of the T wave, and is generally less than 0.44 seconds in normal individuals. In subjects with the long-QT syndrome, the QT is usually longer than 0.44 seconds. Delayed electrical recovery within the heart can be associated with very dangerous, rapid, and chaotic heart rhythms (medical terms for these abnormal heart rhythms are …

Autonomic functions in restrictive cardiomyopathy and constrictive pericarditis: A comparison

Background This study was undertaken to analyze autonomic functions in restrictive cardiomyopathies. Restrictive cardiomyopathies have clinical and hemodynamic similarity with chronic constrictive pericarditis. Autonomic dysfunction has been described in the latter. Methods and Results Autonomic function analysis has not been reported in restrictive cardiomyopathy. Six consecutive patients with restrictive cardiomyopathy were included in this study (5 men, 1 woman, mean age 35 ± 5.4 years). The tests performed were designed to test the sympathetic efferent pathway, that is, by cold hand immersion and loud noise tests, parasympathetic efferent pathway by Valsalva ratio and expiration/inspiration ratio and the baroreceptor function by testing their sensitivity slope. The results were compared with 20 patients with chronic constrictive pericarditis and with 10 healthy age- and sex-matched control subjects previously studied. The rise of systolic blood pressure after cold hand immersion and sudden loud noise was not significantly different compared with control subjects. The expiration/inspiration ratio was 1.1 ± 0.01 compared with 1.57 ± 0.1 in the control group ( p < 0.01). The Valsalva ratio was significantly lower (1.1 ± 0.04) compared with control subjects (1.83 ± 0.1, p < 0.01). The baroreceptor sensitivity was not reduced compared with that in control subjects. In comparison to constrictive pericarditis, sympathetic efferent pathway is preserved in restrictive cardiomyopathy ( p < 0.0001). The parasympathetic efferent pathway is borderline abnormal in restrictive cardiomyopathy but not significantly as compared with constrictive pericarditis ( p = not significant). The baroreceptor sensitivity slope is normal in patients with restrictive cardiomyopathy as compared with significant depression seen in constrictive pericarditis ( p < 0.05). Autonomic functions are better preserved in patients with restrictive cardiomyopathies compared with chronic constrictive pericarditis. Conclusions Autonomic dysfunction is localized to parasympathetic efferent pathway. This is in comparison to constrictive pericarditis, in which severe autonomic dysfunction is a universal feature and includes all segments of autonomic nervous system. (Am Heart J 1998;136:443-8.)

Activation of a distinct arousal state immediately after spontaneous awakening from sleep

In contrast to the many neural studies into the mechanisms of sleep onset and maintenance, few studies have focused specifically on awakening from sleep. However, the abrupt electrographic changes and large brief cardio-respiratory activation at awakening suggest that a distinct, transiently aroused, awake state may exist compared to later wakefulness. To test this hypothesis we utilized the acoustic startle reflex, a standard un-conditioned reflex elicited by a sudden loud noise. This reflex is modulated under specific conditions, one being a diminution of startle when a quieter pre-stimulus is presented immediately before the loud stimulus. This pre-pulse inhibition (PPI) is used as a measure of sensorimotor gating, with smaller PPI indicating less filtering of sensory inputs and increased responsiveness to external stimuli. Eight rats with electrodes for recording sleep–wake state were studied. An accelerometer measured startle responses. The startle reflex was elicited by 115 dB, 40 ms tones. PPI was produced by 74 dB, 20 ms tones preceding the 115 dB tone by 100 ms. Responses within 100 ms were measured. Stimuli were applied either 3–10 s after spontaneous awakenings, or in established wakefulness (>30 s). Responses to the startle stimuli alone were similar in the different awake states ( P=0.821). However, PPI was smaller at awakening from non-REM sleep compared to established wakefulness (45.4±7.5% vs. 74.3±6.1%, P=0.0002). PPI after awakening from REM sleep (52.8±17.9%) was not significantly different than established wakefulness ( P=0.297). Reduced PPI of the startle reflex at awakening from non-REM sleep supports the hypothesis that wakefulness immediately after spontaneous sleep episodes is neurophysiologically distinct from later wakefulness and associated with reduced gating of motor responses to sensory inputs. Spontaneous activation of this distinct, transiently aroused, state upon awakening may serve a protective function, preparing an animal to respond immediately to potentially threatening stimuli.

Auditory and inspiratory gasp-evoked sympathetic skin response: age effects

The sympathetic skin response (SSR) has been employed to assess peripheral neuropathy as an index of sympathetic sudomotor activity. A variety of stimuli can be used to elicit the SSR, but their relative ease of use and reliability have not been studied. In addition, the extent to which age affects the SSR remains unresolved. We compared two different stimuli, a sudden loud noise and an inspiratory gasp, whilst recording SSRs from the hand and foot. We also investigated the effects of age on SSR amplitude and latency in 58 healthy volunteers (ages 13–79). SSRs evoked by the auditory stimulus were recorded in all subjects, while gasp-induced SSRs were not elicited in two subjects. We found that SSRs evoked by the auditory stimulus had less inter- and intra-subject latency and waveform variability than the gasp-induced response. The increased latency variability associated with the inspiratory gasp technique was probably due to triggering errors. Our results confirmed that the amplitude of the SSR is extremely variable and appears to be affected by many factors. Auditory-evoked SSR latencies revealed a significant non-linear increase with age, while SSRs evoked by an inspiratory gasp did not demonstrate age dependence. We conclude that an auditory stimulus is superior to an inspiratory gasp in evoking SSRs, both in terms of consistent appearance and reduced latency variability. As the SSR latency increases significantly with age, this effect should be carefully considered when interpreting the response.

Inheritance of Tetanic Torticollar Spasms in Turkeys

Tetanic torticollar spasms (TT) refers to a neurologic disorder observed in a line of Medium White turkeys. The condition is characterized by the dorsomesial extension of the neck and head such that the head rests on the back with the beak directed upwards. The spasms vary in duration from 1 to 5 s to longer than 1 min followed by the resumption of normal posture. The spasms appear to be spontaneous but can be induced by sudden loud noises and eating and drinking. When expressed in poults at hatching the condition is usually lethal due to starvation and dehydration. Typically, TT is expressed during the first 7 days posthatching but can be as late as 18 wk of age. Breeding tests indicate that TT is the expression of a sex-linked recessive gene with incomplete penetrance, 86%. Microscopic examination of the otoconia in the inner ears and histologic examination of the cerebellum and brainstem of TT turkeys have not revealed any abnormality. The gene symbol tt is proposed.

Effect of dialysis and renal transplantation on autonomic dysfunction in chronic renal failure

Autonomic functions were evaluated in 25 nondialyzed patients with chronic renal failure and eight controls. Eight patients were reassessed after 6.6 +/- 1.0 weeks of hemodialysis and 12 patients were restudied 24 +/- 4.0 weeks after renal transplantation. In addition, six patients who had been on maintenance hemodialysis for a duration of 21.5 +/- 3.0 weeks were also studied. Autonomic function tests, including blood pressure and heart rate response to sudden loud noise, mental arithmetic, hand immersion in cold water, Valsalva maneuver, change in posture and respiration, were performed using brachial artery cannulation and continuous monitoring by electrocardiogram. Baroreceptor sensitivity slope was determined using bolus injections of phenylephrine. Supine and standing plasma norepinephrine levels were measured. The cold pressor test, response to sudden loud noise and mental arithmetic were normal in nondialyzed patients with chronic renal failure, suggesting an intact efferent sympathetic pathway. The plasma norepinephrine concentration varied widely but the mean value was similar to the control group (P greater than 0.05). Expiration/inspiration ratio, lying/standing ratio, Valsalva ratio and the baroreceptor sensitivity slope were significantly abnormal (P less than 0.001) in nondialyzed patients. This indicates a defective efferent parasympathetic pathway and depressed baroreceptor sensitivity. The blood pressure response to phenylephrine was lower in the uremics, suggesting a reduced end-organ responsiveness to alpha agonists. The presence of hypertension did not affect autonomic function. The heart rate response to standing and the baroreceptor sensitivity were significantly lower (P less than 0.05) in patients who developed hypotension during hemodialysis. Lower baroreflex sensitivity could contribute to hypotension during dialysis. Autonomic functions remained unaltered after short- and long-term dialysis.(ABSTRACT TRUNCATED AT 250 WORDS)