Disease latency in Creutzfeldt-Jakob disease via dural grafting: a case report

The case of a 57-year old man is reported who had been operated upon for cerebellar angioblastoma more than 19 years previously. Having received a lyophilized dural patch he developed Creutzfeldt–Jakob disease of which he died 19 months later. This is the longest latency with dura-associated Creutzfeldt–Jakob disease reported so far.     

The integration of parallel and serial processing mechanisms in visual search: evidence from eye movement recording

We examined timing and scanning paths of eye movements during a visual search task, in which subjects had to detect, as quickly as possible, the presence or absence of a target among distractors [Q-like element among O stimuli (QvsO) and vice-versa (OvsQ)]. According to an influential theory [Treisman, A. & Gelade, G. (1980) Cognitive Psychol, 12, 97--136; Treisman, A. & Sato, S. (1990) J. Exp. Psychol. Hum. Percept. Perform., 16, 459--478], only tasks yielding nonflat search functions (OvsQ) involve focal attention. Alternative models propose that all kinds of visual search are resolved by a biased competitive process, working in parallel across the visual field. Data show that QvsO and OvsQ tasks are characterized by quantitative rather than by qualitative differences in search strategy. No differences between the two tasks were found regarding either the percentage of saccades foveating single stimulus items or the timing of the button response with respect to the onset of the last foveation saccade within a trial. Furthermore, the number of saccades made during search predicted very accurately the time required to accomplish the task and fixation times were independent of the number of stimulus items. On the basis of our results there is no reason to postulate the occurrence of shifts of visuospatial attention, other than those associated with the executions of saccadic eye movements, which are driven by a parallel feature analysis of the visual scene, in both types of search tasks. A time-limited competitive model for attentive target identification, in which both parallel (competitive) and serial (attentive) processing mechanisms are integrated, can account for these findings, providing a unified conceptual framework for all kinds of visual search.     

声诱发的短潜伏期负反应与前庭诱发的肌源性电位关系初步研究

目的研究声诱发的短潜伏期负反应(acoustically evoked short latency negative response,ASNR)的特点,并初步证实该电位的前庭源性,即与前庭诱发的肌源性电位(vestibular evoked myogenic potentials,VEMP)同源。方法分别检测28例健康成人、16例前庭疾病和1例全聋患者的VEMP和ASNR,比较ASNR与VEMP之间的关系。结果ASNR正常引出率为87.5%,潜伏期正常值为3.50±0.25ms;2倍标准差作为正常值的上、下限,ASNR潜伏期的范围为3~4ms,阈值为80~90dB nHL。16例前庭疾病患者均行双侧检查,在VEMP消失的9耳(9例)中,ASNR均未引出;VEMP低振幅的8例(8耳)中,5例(5耳)未引出ASNR,3例(3耳)ASNR正常引出。5例梅尼埃病患者接受甘油试验,1例(2耳)甘油试验前后VEMP与ASNR均正常,2例(4耳)双侧VEMP与ASNR甘油试验前异常,甘油试验后正常,1例(1耳)患侧VEMP正常,甘油试验前后无变化,ASNR由异常变为正常;1例(2耳)VEMP甘油试验前双侧异常,甘油试验后正常,但ASNR均未引出。1例听力正常的前庭神经炎患者,患侧VEMP未引出,ASNR电位也未引出。1例先天性全聋患者人工耳蜗植入前,VEMP、ASNR正常引出;植入后,术侧VEMP振幅降低,ASNR未引出。结论ASNR与VEMP可能均源于球囊。鉴于目前的结果,在不便进行VEMP检测时可用ASNR替代。     

Bilateral recording of early auditory evoked responses in the cat

The brain-stem electric responses of the cat evoked by a short 4 kHz tone burst have been differentially recorded between vertex and both ipsilateral and contralateral ear electrodes. Six vertex-positive waves can be recognised in both recordings. Animals with hereditary unilateral anacusis were studied in order to avoid cross-stimulation of the opposite ear. The cochlear microphonic and summating potential can be readily recorded in young animals, occur simultaneously in both tracings, and show polarity inversion at the contralateral electrode. The later neural potentials have the same polarity and practically identical latencies in the ipsilateral and contralateral recordings, whilst the first three brain-stem waves show approximate polarity inversion and variable latency relationships in the two recording situations. It is concluded that none of the brain-stem waves represents electric activity from a discrete generator.     

Does display sensitivity influence motor latency determination?

It is known that display sensitivity can affect onset latency measurement of compound muscle action potentials (CMAPs). We compared two display sensitivities with respect to intrarater and interrater reliability and measured to what degree display sensitivity influences the motor latency. We asked seven raters to mark the onset points of median CMAPs from 24 patients printed with display sensitivities of 5 mV/division and 0.5 mV/division on paper. The onset latencies were measured, and intraclass correlation coefficients (ICCs) were calculated. Most of the raters had excellent intrarater repeatability within a single sensitivity display setting. In contrast, the intrarater reliability using two different sensitivity settings was poor. ICCs calculated for interrater reliability were 0.93 at 0.5 mV/division and 0.91 at 5 mV/division. On average, the latencies measured at 5 mV/division were about 0.3 ms longer. We conclude that reliability of latency measurement is excellent at either sensitivity; however, it is important to use a consistent sensitivity in order to avoid making measuring errors. Muscle Nerve, 2009     

Characteristics of brainstem auditory evoked potentials of students studying folk dance★

BACKGROUND： Previous experiments have demonstrated that brainstem auditory evoked potential is affected by exercise, exercise duration, and frequency.
OBJECTIVE： Comparing the brainstem auditory evoked potential of students studying folk dance to students studying other subjects. DESIGN： Observational contrast study.
SETTING： Physical Education College, Shandong Normal University PARTICIPANTS： Fifty-five female students were enrolled at Shandong Normal University between September and December in 2005, including 21 students that studied folk dance and 34 students that studied other subjects. The age of the folk dance students averaged （19 ± 1） years and dance training length was （6.0 ± 1.5） years. The students that studied other subjects had never taken part in dance training or other physical training, and their age averaged （22 ± 1） years, body height averaged （162 ± 5） cm, body mass averaged （51 ± 6） kg. All subjects had no prior ear disease or history of other neurological disorders. All students provided informed consent for the experimental project.
METHODS： The neural electricity tester, NDI-200 （Shanghai Poseidon Medical Electronic Instrument Factory） was used to examine and record Brainstem Auditory Evoked Potential values of the subjects during silence, as well as to transversally analyze the Brainstem Auditory Evoked Potential values. The electrode positions were cleaned and degreased with soapy water, followed by ethanol. The selected bipolar electrodes were situated on the head： recording electrodes were placed at the Baihui acupoint, and the reference electrode was placed at the mastoid of the measured ear, with grounding electrodes in the center of the forehead. Brainstem Auditory Evoked Potential values were elicited by monaural stimulation of a ＂click＂ though an earphone; the other ear was sheltered by the white noise. The click intensity was 102 db, the stimulation frequency was 30 Hz, the bandpass filters were 1 000-3 000 Hz, the sensitivity     

Pavlovian conditioning of discriminatively elicited eyeblink responses with short onset latency attributable to lengthened interstimulus intervals

Conditioned eyeblink responses were obtained in cats by pairing click (CS) with glabella tap (US) and electrical stimulation of the hypothalamus (HS). Hiss was used as a discriminative stimulus (DS). Onset latencies of conditioned responses (CRs) of 20–56 ms were obtained by using an interstimulus interval (ISI) of 570-10 ms between CS and US-HS. Longer latency (90–320 ms) blink CRs were obtained with ISIs of 340-240 and 340-10 ms. The timing of associatively learned movements has been thought to increase with lengthening of the intervals between CS and US presentation. The production of shorter latency CRs of this type by lengthening the ISI is a novel result and one unexpected from widely held beliefs.     

The period of latency before a muscle receptor generates an action potential as a response to a muscle stretch

Six primary (Ia) and seven secondary (II) muscle spindle afferents and eight Golgi tendon organ afferents (Ib) from the tibial anterior muscle of the cat, recorded at the dorsal roots, were subjected to a sinusoidal stretch of the host muscle, the frequency of which increased linearly from 2 to 80 Hz over four different lengths of time. Both the amplitude of the sinusoidal stretch and the prestretch of the muscle were varied. The phase of the action potentials was determined. The phase of the action potential, driven 1:1, increased linearly with frequency. From the gradient of the phase of this action potential the muscle-muscle receptor latency was determined, i.e., the period of latency between the stretch of the muscle and the occurrence of the action potential at the muscle nerve where it enters the muscle. The muscle-muscle receptor latency had values lying between 3 and 8 ms: it was dependent on the experimental parameters and became shorter as the conduction velocity of the afferent fiber increased. In three experiments the muscle latency was determined, i.e., the period of latency before the stretch was transferred from the tendon of the muscle to the proximal third of the muscle belly. The muscle was stretched sinusoidally under the same varying parameters as given above. The length changes occurring in the proximal third of the muscle were measured with a piezo element. The muscle latency was determined from the slope of the phase of the zero points of the sinusoidal piezo length changes; the phase increases linearly with frequency. The muscle latency had values lying between 6 and 15 ms: it was dependent on the experimental parameters. The muscle spindle latency, i.e., the period of latency between the stretch of the polar parts of the intrafusal muscle fibers and the recording of the action potentials from the spindle nerve near the spindle capsule, was determined from 5 Ia fibers and 1 II fiber of isolated muscle spindles. The isolated muscle spindle was stretched under the same varying parameters as given above. The muscle spindle latency was determined from the slope of the phase of the phase-locked action potential. The muscle spindle latency as measured by our method proved to be 0 ms. The latencies of the three elements and their dependence on the experimental parameters are discussed in the light of the transfer properties of the muscle and the muscle receptors.     

Narcolepsy/cataplexy. IV: Diagnostic value of daytime nap recordings

Sleep and wakefulness patterns in daytime naps of 50 patients with narcolepsy/cataplexy were compared with those of 50 controls. Each subject was monitored polygraphically during 2 one-hour nap periods. A sleep-onset REM period in either of the 2 daytime naps was observed to have a higher diagnostic sensitivity (78%) than an abnormally shortened sleep latency (68%). However, the specificities of a sleep-onset REM period (88%) or abnormally shortened sleep latency (90%) were quite similar. When the occurrence of either a sleep-onset REM period or a shortened sleep latency was evaluated in either of the two naps, the overall sensitivity was increased to 84% while the specificity was decreased only to 80%. The limitations of and indications for the use of testing for sleep and REM latencies in the diagnosis of narcolepsy in clinical practice are discussed.