Short Tone Bursts Research Articles

Aspect determination using a transducer with a spiral wavefront: Basic concept and numerical modeling.

A circular cylindrical acoustic transducer whose direction of motion is radial produces an outgoing signal whose wavefronts are concentric circles. A similar transducer can be designed to generate spiral wavefronts where the phase of the outgoing wave changes by 360 deg in one revolution around the transducer. If these two transducers are used in tandem as a beacon, short tone bursts fired consecutively from each transducer can be used to determine the aspect angle to a receiver relative to the beacon. This is an acoustic version of the VHF omnidirectional ranging systems currently in use in airplane navigation. There are several ways of designing a transducer to produce the spiral wavefront required for the beacon. Several of these designs have been modeled numerically to understand the details of the outgoing field and their impact on aspect determination. [Work supported by ONR.]

Hallazgos de potenciales vestibulares miogénicos evocados en la esclerosis múltiple

Vestibular evoked myogenic potential (VEMP) elicited by acoustic stimulation, has been proposed in the assessment of vestibulospinal pathways. To research the clinical utility of VEMP on multiple sclerosis (MS). Forty-four individuals were evaluated (30 normal state and 14 had MS). The acoustic stimuli were short tone burst (1 kHz, 118 dBNa, rise-fall 1 ms, plateau 2 ms) presented through a supra-aural earphone. The stimulation rate was 5 stimuli per second. All the healthy subjects showed a normal VEMP response. In the MS group, abnormal VEMP was recorded among 92.8% of patients and normal in just one case. The P13-N23 increased of prolongation which was the most frequently alteration (57.1%), followed by absence of response among four (28.5%) cases. VEMP was considered a good method of diagnostic support of vestibulospinal tract in cases of MS.

Effects of eye position on the vestibular evoked myogenic potential

Conclusion: The position of a subject's eyes during vestibular evoked myogenic potential (VEMP) recording significantly alters the magnitude of the response. This change is largely due to an alteration in the tonicity of the sternocleidomastoid muscle (SCM) caused by variations in the position of the eye. However, even if electromyographic (EMG) normalization is conducted effects of eye position remain. Objective: To determine if eye position has a significant effect on the magnitude of the VEMP. Subjects and methods: VEMPs were collected from 32 ears measured on 16 healthy subjects. The recordings were made unilaterally using the head turn method. The acoustic stimuli were 500 Hz air-conduction short tone bursts. VEMPs were measured in three recording conditions: (i) eyes in the same direction as head turn, (ii) eyes straight ahead, (iii) eyes in the opposite direction to head turn. Results: All 32 ears tested showed a VEMP response with eyes in all three positions. Repeated measures analysis of variance (RM-ANOVA) verified an overall significant effect of eye position (p<0.001). Post hoc paired t tests revealed statistically significant differences between the eyes opposite and the other two conditions (p<0.001). Normalization of the VEMP magnitude using pre-stimulus EMG reduced the effect; however, some variability remained.

Effects of Gaze Positions on Ocular Vestibular Evoked Myogenic Potentials

Background and Objectives：Recent works have demonstrated the existence of ocular vestibular evoked myogenic potentials (OVEMPs), which reflects otolith-ocular reflex. The purpose of this study was to identify an appropriate gaze position to detect OVEMPs produced by air-conducted sound stimulation in healthy subjects. Subjects and Method：Twenty four healthy subjects (35 ears) were included in this study. Surface electromyographic activity was recorded from active electrodes placed inferior to each eye. Stimulation with 500 Hz short tone bursts was used to activate the vestibular end-organs. Results：Sound stimulation evoked negative-positive biphasic responses on both ipsilateral and contralateral eyes, while responses were contralateral eye-dominant. Contralateral eye responses had higher response incidence and larger amplitudes. Altering the direction of gaze generally changed the incidence and size of the inter-peak amplitudes. The higher incidence and larger amplitudes were recorded when the eyes are directed to the superior and ipsilateral side to the sound stimulation. In that gaze position, the amplitude was 5.3 μV, the first negative peak latency was 10.5 ms and the following positive peak latency was 15.4 ms on the average. Conclusion：OVEMPs can be evoked using an air-conducted 500 Hz tone burst and are best recorded contralaterally with a upward gaze towards the source of sound stimulation. Further changes of the test parameters are needed for higher and consistent responses. (Korean J Otorhinolaryngol-Head Neck Surg 2009;52:215-9)

Ocular Vestibular Evoked Myogenic Potential in Healthy Subjects: A Comparative Study with Cervical Vestibular Evoked Myogenic Potential

Background and ObjectivesZZWhile vestibular evoked myogenic potentials (VEMPs) can be measured from extra-ocular muscle as well as cervical muscle, there are uncertainties about the patterns and discomfort level of ocular vestibular evoked myogenic potentials (oVEMPs). This study is to identify the properties of oVEMPs parameters and degree of subjective discomfort when compared to cervical vestibular evoked myogenic potentials (cVEMPs) in healthy subjects. Subjects and MethodZZTwenty volunteers with normal hearing were enrolled in this study. The oVEMPs were recorded from electrodes placed beneath the eyes using ipsilateral and contralateral acoustic stimulation with 500 Hz short tone bursts with subjects in sitting position and maximal upward gaze. The cVEMPs were measured using 500 Hz short tone bursts with subject in supine position and their head elevated and turned away from the test side. The latency, interlatency and interamplitude of oVEMPs responses were compared to those of cVEMPs. The subjective discomfort levels of oVEMPs and cVEMPs were compared using a questionnaire survey. ResultsZZThe cVEMPs appeared as positive-negative biphasic responses in all 40 ears whereas oVEMPs were measured in 27 ears (67.5%) with ipsilateral stimulation and 20 ears (85%) with contralateral stimulation which appeared as negative-positive biphasic responses. The oVEMPs had smaller amplitude than the cVEMPs. The oVEMPs thresholds tended to have higher level than the cVEMPs thresholds. The 18 subjects (90%) reported that the discomfort level of oVEMPs measurement was lower or equal to that of cVEMPs measurement. ConclusionZZoVEMPs test may be used as a complementary and comfortable diagnostic tool for evaluating the integrity of vestibular-ocular system. Korean J Otorhinolaryngol-Head Neck Surg 2009;52:968-73 Key WordsZZVestibulo-ocular reflex·Evoked potentials·Saccule·Otolith.

Vestibular evoked myogenic potentials in chronic otitis media before and after surgery

Conclusion. The pathology of chronic otitis media (COM) could delay and reduce the energy transfer of sound to the inner ear. The significant improvement of postoperative vestibular evoked myogenic potential (VEMP) response rate and p13 latencies in the group of patients with no or negative postoperative ABG gain provided evidence that the sound energy inducing a VEMP might be different from the energy producing the auditory perception. Objective. To evaluate the VEMP in patients with COM before and after surgery. Subjects and methods. Twenty-four subjects with unilateral COM were enrolled. A pure tone audiogram and VEMP using 500 Hz unilateral short tone-burst stimulations were recorded before and 3 months after surgery. The postoperative VEMP responses were compared with the responses before surgery and the healthy controls. Results. After surgery, the 500 Hz air–bone gap (ABG) decreased significantly and the VEMP response rate increased significantly from 41.7% to 66.7% (p<0.05, bi-test). However, both the preoperative and postoperative p13 latencies were significantly longer than those of the healthy controls (p<0.05, Wilcoxon rank-sum test). In the 18 patients whose 500 Hz ABG did not improve with surgery, the p13 latencies were significantly shorter postoperatively (p<0.05, sign test), and the response rate also improved significantly from 44.4% (8/18) to 77.8% (14/18) (p<0.05, bi-test).

SU‐GG‐J‐196: Vascular Occlusion by Acoustically Vaporized Droplets for Potential Targeted Enhancement of Thermal Therapies

Purpose: Acoustic droplet vaporization (ADV) of perfluorocarbon droplets with boiling points below ambient temperature shows promise for spatially and temporally targeted vascular occlusion. Vascular occlusion of a tumor or other target tissue can decrease the local heat dissipation relative to adjacent normal tissues during less directed or slow thermal therapies, such as RF or ultrasonic ablation. Also, encapsulated drugs can be released with the occluding bubbles into the target tissues. Method and Materials: In six canines, in vivo gray scale imaging and color flow and pulse wave (PW) Doppler imaging were employed with low concentration droplet injections to identify exteriorized target arteries or tissues, avoiding major adjacent veins. Short tone bursts at 3.5 MHz with 0.25% duty cycle were used during bolus passage to vaporize droplets with concentrations comparable to clinical ultrasound contrast agent recommendations. Studies included multiple intracardiac (IC) and intravenous (IV) injections, the latter with lipid, rather than albumin, shell. Results: Bubble production by ADV in arteries or tissues is easily visible in gray scale images. Both IC and IV injections repeatedly produced ADV at will in the renal or segmental artery, each injection and ADV generating vascular occlusion as seen by gray scale and Doppler imaging. Mean cortex occlusion was ∼85% by colored microspheres in the targeted kidney or renal pole with an ∼10 min half life per droplet dose. Cardiopulmonary symptoms occurred in some IC injections. ADV was successful in a canine prostate using an intercavitary imaging array for ADV and targeting. Conclusion: Keys to the new, consistent success with both IC and IV injections include adequate concentrations of droplets, use of frequencies with ADV threshold well below those for cavitation, and reliable targeting. Conflict of Interest: This work was supported in part by NIH RO1EB00281.

Vestibular-Evoked Myogenic Potential (VEMP) to Evaluate Cervical Myelopathy in Human T-Cell Lymphotropic Virus Type I Infection

Cross-seccional analysis. To define the clinical usefulness of vestibular-evoked myogenic potential (VEMP) in detecting cervical medullar involvement related to human T-cell lymphotropic virus type 1 (HTLV-1) associated myelopathy/tropical spastic paraparesis (HAM/TSP). VEMP is generated by acoustic or galvanic stimuli, passing through the vestibulo-spinal motor tract, the spinal nerves and recorded by means of surface electrodes on the sternocleidomastoid muscle. HAM/TSP is a progressive inflammatory myelopathy with predominant lesions at the thoracic spinal cord level, although the cervical spine can be affected. VEMP may be of value to investigate cervical myelopathy. Seventy-two individuals were evaluated of whom 30 HTLV-1 were seronegative and 42 HTLV-1 seropositive (22 asymptomatic, 10 with complaints of walking difficulty without definite HAM/TSP and 10 with definite HAM/TSP). VEMP was recorded using monaural delivered short tone burst (linear rise-fall 1 millisecond, plateau 2 milliseconds, 1 KHz) 118 dB NA, stimulation rate of 5 Hz, analysis time of 60 milliseconds, 200 stimuli, band pass filtered between 10 and 1.500 Hz. VEMP was normal in the seronegative group (30 controls). In the seropositive, abnormal VEMP was seen in 11 of 22 (50%) of the HTLV-1 asymptomatic carriers, in 7 of 10 (70%) of those with complaints of walking difficulty and in 8 of 10 (80%) of the HAM/TSP patients. In this last group, the pattern of response was different. No VEMP response was more frequent when compared with the HTLV-1 asymptomatic group (2-tailed P-value = 0.001). VEMP may possibly be useful to identify patients with cervical myelopathy and to distinguish variable degrees of functional damage. Minor injury would be related to latency prolongation and major injury to no potential-evoked response.

電磁気刺激による神経疾患の診断と治療 電気刺激による前庭機能障害の診断

We report on the combined application of acoustic VEMP and electric VEMP for the diagnosis of vestibular dysfunction. For the recording of the acoustic VEMP, we used click (0.1msec, 95dBnHL) and 500-Hz short tone burst (rise/fall time 1msec plateau time 2msec, 95dBnHL) stimuli. For the recording of the electric VEMP, we used 3-mA (1msec) electrical stimulation. In the first part of the study, we applied this combined stimulation to patients who showed absent VEMP to click stimulation. Patients with labyrinthine lesions such as Meniere's disease showed normal electrical VEMP, although they showed no response to click stimulation. On the other hand, almost all patients with nerve lesions such as acoustic neuroma showed absent or decreased VEMP to electrical stimulation. These results suggest that electrical VEMP in patients with absent click-VEMP could be useful for the differentiation of labyrinthine lesions from nerve lesions. We applied this testing method to patients with vestibular neuritis and Ramsay Hunt syndrome. Patients with vestibular neuritis and Ramsay Hunt syndrome were classified in 2 groups. The majority had nerve lesions, while some patients had labyrinthine lesions. In the second part of the study, we applied the combined stimulation to patients with preserved acoustic VEMP. Then we calculated the acoustic-electric ratio of VEMP. In comparison with that in healthy subjects, patients with acoustic neuroma, and the unaffected sides of patients with Meniere's disease, the affected sides in patients with Meniere's disease showed a smaller acoustic-electric ratio of VEMP. These findings suggest hat the combined application of electrical VEMP and acoustic VEMP could be useful in the differentiation of labyrinthine lesions from nerve lesions even in patients with preserved acoustic VEMP.

Stimulus Repetition Rate and the Reference Levels for Clicks and Short Tone Bursts: A Warning to Audiologists, Researchers, Calibration Laboratories, and Equipment Manufacturers

To make the audiologic community aware of a technical issue with potential for misunderstanding that could affect the design, calibration, and use of auditory brainstem response (ABR) systems. Two international standards published in 2007 relating to the stimuli commonly used in ABR tests were studied and the behavior of a commercially available ABR system examined with regard to the relationship between stimulus level and repetition rate. There is potential for misunderstanding of the need to compensate for the effect of stimulus rate on stimulus level. Although rapidly presented stimuli appear louder as the rate is increased, it is inappropriate to compensate for this when calibrating the stimulus level of ABR systems. Users of ABR systems should, if possible, use the stimulus reference levels now available in an international standard rather than establish local values. No adjustment of level should be made to account for different stimulus repetition rates. Users of ABR systems should check their systems to ensure that no automatic level adjustment is made; if necessary, equipment manufacturers should be consulted.

Stimulus Repetition Rate and the Reference Levels for Clicks and Short Tone Bursts: A Warning to Audiologists, Researchers, Calibration Laboratories and Equipment Manufacturers

Purpose To make the audiologic community aware of a technical issue with potential for misunderstanding that could affect the design, calibration, and use of auditory brainstem response (ABR) syste...

Vestibular-evoked extraocular potentials by air-conducted sound: Another clinical test for vestibular function

Objective The purpose of this study was to identify an appropriate way to detect vestibular-evoked extraocular potentials (oVEMPs) produced by air-conducted sound stimulation in healthy subjects and to apply this test clinically in patients with various vestibular disorders. Methods Ten healthy subjects were included in this study. Surface electromyographic (EMG) activity was recorded from active electrodes placed on the face just inferior to each eye. Stimulation with 0.1 ms clicks and 500 Hz short tone bursts was used to activate the vestibular end-organs in healthy subjects. We also tested 12 patients with unilateral vestibular disorders using 500 Hz short tone bursts. Results In healthy subjects, negative–positive biphasic responses with short latency by air-conducted click (the first negative peak latency = 8.8 ms and the following positive peak latency = 14.5 ms on the average) (oVEMP) were only identified beneath the eye contralateral to the stimulating ear. On the other hand, stimulation with 500 Hz short tone bursts evoked negative–positive biphasic responses (the first negative peak latency = 10.5 ms and the following positive peak latency = 15.9 ms on the average) on both ipsilateral and contralateral eyes, while responses were contralateral eye-dominant. Contralateral eye responses by 500 Hz short tone bursts had higher response prevalence and larger amplitudes than clicks. In patients, oVEMPs evoked by the affected side stimulation tended to decrease or lacked a response. The presence of oVEMPs and cVEMPs coincided well in patients when 500 Hz short tone bursts were presented. Conclusions oVEMPs can be evoked using air-conducted 500 Hz tone burst and are best recorded contralaterally on upgaze. Significance oVEMPs by air-conducted sounds could be a useful alternative clinical test for patients with vestibular lesions.

Cortical representation of saccular vestibular stimulation: VEMPs in fMRI

Short tone bursts trigger a vestibular evoked myogenic potential (VEMP), an inhibitory potential which reflects a component of the vestibulocollic reflex (VCR). These potentials arise as a result of activation of the sacculus and are expressed through the vestibulo-collic reflex (VCR). Up to now, the ascending projections of the sacculus are unknown in humans, only the representation of the semicircular canals or the entire vestibular nerve has been demonstrated. The aim of this study was to determine whether a sacculus stimulus that evoked VEMPs could activate vestibular cortical areas in fMRI. To determine this, we studied the differential effects of unilateral VEMP stimulation in 21 healthy right-handers in a clinical 1.5 T scanner while wearing piezo electric headphones. A unilateral VEMP stimulus and two auditory control stimuli were given in randomized order over the stimulated ear. A random effects statistical analysis was done with SPM2 ( p < 0.05, corrected). After exclusion of the auditory effects, the major findings were as follows: (i) significant activations were located in the multisensory cortical vestibular network within both hemispheres, including the posterior insular cortex, the middle and superior temporal gyri, and the inferior parietal cortex. (ii) The activation pattern was elicited bilaterally with a predominance of the right hemisphere in right-handers. (iii) Saccular vestibular projection was predominantly ipsilateral, whereas (iv) pure acoustic stimuli were processed with a predominance of the respective contralateral and mainly in the left hemisphere. This is the first demonstration by means of fMRI of the cortical representation of the saccular input at cortical level. The activation pattern is similar to that known from the stimulation of the entire vestibular nerve or the horizontal semicircular canal. Our data give evidence of a task-dependent separation of the processing within the vestibular otolith and the auditory systems in the two hemispheres.

Clinical value of tone burst vestibular evoked myogenic potentials at threshold in acute and stable Ménière's disease

The objectives of this preliminary, prospective, cohort study were to ascertain the characteristics of vestibular evoked myogenic potentials at threshold levels in two groups of Ménière's disease patients - acute and stable - and to identify whether vestibular evoked myogenic potentials can provide any specific, objective information to distinguish acute from stable Ménière's disease. The study was based at a tertiary neuro-otology centre. Twenty adult patients who fulfilled the American Academy of Otolaryngology-Head and Neck Surgery criteria for Ménière's disease were divided into two groups: 11 patients with acute Ménière's disease and nine patients with stable Ménière's disease. Eighteen healthy adult volunteers served as controls. All subjects underwent vestibular evoked myogenic potential testing with ipsilateral, short tone burst stimuli at 500 Hz, as well as pure tone audiometry. The patients also underwent caloric testing. Vestibular evoked myogenic potentials were present in all controls, and were present in 65 per cent of patients but absent in 35 per cent. The mean absolute threshold (Tvestibular evoked myogenic potential) +/- standard deviation in normal controls was 116 +/- 7.7 dBSPL; this did not differ statistically from that in patients, nor did it differ between acute and stable Ménière's disease. The p13/n23 latencies at the threshold levels in the normal, acute and stable groups (mean +/- standard deviation) were respectively: 15 +/- 2.2 ms/23.0 +/- 2.5 ms; 15.7 +/- 0.9 ms/23.7 +/- 0.9 ms; and 15.3 +/- 2.0 ms/24.2 +/- 1.9 ms. The mean interaural amplitude difference ratio (IAD) +/- standard deviation was significantly higher in the stable group compared with the acute group (0.54 +/- 0.33 vs -0.15 +/- 0.22; p = 0.007) and with the controls (0.54 +/- 0.33 vs 0.1 +/- 0.22; p = 0.05). The parameter that best differentiated acute from stable Ménière's disease at threshold was the interaural amplitude difference ratio. Therefore, this parameter may be used to monitor the clinical course of Ménière's disease.

Tone burst–galvanic ratio of vestibular evoked myogenic potential amplitudes: A new parameter of vestibular evoked myogenic potential?

Objective To clarify whether the ratio of tone burst vestibular evoked myogenic potential (VEMP) amplitude to galvanic (electric) VEMP amplitude can be a useful indicator of peripheral vestibular disorders, especially labyrinthine disorders. Methods Twelve healthy volunteers and 12 patients with endolymphatic hydrops (EH) were enrolled in this study. VEMP was recorded using 500 Hz short tone bursts (135 dBSPL, rise/fall time 1 ms, plateau time 2 ms) and galvanic stimulation (3 mA, 1 ms). Amplitudes of p13–n23 (tone burst) and p13g–n23g (galvanic) were corrected using background muscle activity. We defined the ratio of the corrected amplitude of p13–n23 to the corrected amplitude of p13g–n23g as TGratio. Results The mean ± SD of logarithmic value of TGratio (LTGratio) of healthy volunteers was 0.34 ± 0.12. LTGratios in patients were 0.002 ± 0.24 on the affected side and 0.34 ± 0.14 on the unaffected side. LTGratio on the affected side of patients was significantly smaller than the ratio on the unaffected side and the ratio of healthy volunteers. Among the 12 patients with EH, 8 patients (66%) had significantly decreased LTGratio (smaller than mean−2SD of healthy volunteers). Conclusions Patients with EH had decreased ratio of tone burst VEMP amplitude to galvanic VEMP amplitude. Significance TGratio (or LTGratio) could be a new promising parameter of VEMP as it can be calculated from results of one side.

Comparison of Short Tone Burst-evoked and Click-evoked Vestibular Myogenic Potentials in Healthy Individuals

Vestibular evoked myogenic potential (VEMP) is one of the clinical tools to evaluate vestibular function. The VEMP can be recorded from sternocleidomastoid muscle by auditory stimulation with various sound stimuli. The aim of this study was to compare the VEMP responses evoked by short tone burst (STB) with those evoked by click stimuli in healthy young individuals. Twenty-two healthy volunteers (11 males, 11 females; 44 ears), with ages ranging from 17 to 30 years were enrolled in this study. Subjects were instructed to lie in supine position and elevate their heads unsupported. The VEMP was recorded using 500Hz STB and then click sound stimuli to each ear. The latency p13, n23, peak-to-peak p13-n23 amplitude and VEMP asymmetry ratio (VAR) were obtained for further analysis. The VEMP responses were present in all subjects. The latencies p13 and n23 of STB-VEMP were significantly longer, and the p13-n23 amplitudes were significantly greater for STB-VEMP (p<0.05, paired t test), as well. The VAR, however, showed no significant difference between the 2 stimuli. The latency n23 of click VEMP in our study was significantly different from that of 1 of the other studies (p<0.05). The VEMP responses were significantly different between the stimuli of STB and click, and the norms of different stimuli should be established for clinical interpretations. For clinical diagnosis using VEMP, we recommend STB stimuli because the latencies and amplitudes of click were significantly different among several labs, including ours.

Eye movements induced by short tone burst stimulation: A video-oculography study

Eye movements induced by short tone burst stimulation: A video-oculography study

Tilted aluminum cylinder acoustic scattering properties and holographic and synthetic aperture sonar (SAS) images

A solid bluntly‐truncated aluminum cylinder in water is a convenient target for exploring the relationship between free‐field scattering properties of short tone‐bursts and acoustic images. These experiments concern situations where the product ka of the acoustic wave number and the cylinder radius exceed about 12. There are several prominent features in the tilt‐angle dependence of the time‐resolved backscattering. Some of these features are also present in prior measurements for tilted stainless steel cylinders using relatively long tone bursts [K. Gipson and P. L. Marston, J. Acoust. Soc. Am. 106, 1673–1680 (1999); K. Gipson and P. L. Marston, J. Acoust. Soc. Am. 107, 112–117 (2000)]. Prominent features include responses caused by guided generalized Rayleigh waves associated with meridonal rays, helical rays, and face crossing rays. These features are easily observed for tilted aluminum cylinders in the scattering of short tone bursts for cylinders having length‐to‐diameter ratios of 3 and 5. Guided Rayleigh waves also influence the appearance of the imaged cylinders in holographic and synthetic aperture sonar (SAS) images constructed using far‐field bistatic data. This influence on the images is explained using ray theory. [Supported by ONR.]

Effect of head position on vestibular evoked myogenic potentials with toneburst stimuli

Conclusion. The present study demonstrated the robustness of VEMP testing with toneburst stimuli, since it is hardly affected by head position, i.e. base or tonic excitation levels of the saccule and inferior vestibular nerve. However, the small but highly significant difference found in latency should not be neglected: the gravitational axis in the upright position may have some special effect on tonic excitation of the saccule. Objectives. To evaluate the effect of head positions on vestibular evoked myogenic potentials (VEMPs) with toneburst stimuli. Materials and methods. VEMPs were recorded with short tonebursts of 500 Hz in 14 normal subjects in 5 head positions (upright, nose up, ear up, nose down, and ear down). The three parameters analyzed were: 1) latency of p13, 2) latency of n23, and 3) corrected amplitude of p13-n23 (CA p13-n23). Results. One-way repeated measures ANOVA showed significant effects on both p13 (p=0.0245) and n23 (p<0.0001) latencies, but not on CA p13-n23. Bonferroni's post hoc test demonstrated that there were significant differences in n23 latency between the upright position and all other head positions leaning on the bed.

Frontal lobe involvement in the processing of meaningful auditory stimuli develops during childhood and adolescence

Auditory event-related N1b reflects attention-related processing in bilateral temporal auditory cortex. Frontal contributions indicating an orienting reaction have been suggested. We analyzed the maturation of frontal contributions to the auditory event-related potential following the warning stimulus in a contingent negative variation (CNV) task by high-resolution current source density mapping and spatio-temporal source analysis in 80 healthy subjects and 121 primary headache patients (migraine with/without aura, tension type headache) from 6 to 18 years; as increased orienting responses and disturbed maturation have been described in migraineurs. A selective local increase of N1b with age occurred at mid-frontocentral leads. This increase could not be explained sufficiently by overlapping bilateral temporal sources but pointed towards additional frontal activation over the supplementary motor area (SMA) in adolescents which was absent in children. A second frontal N1 component peaked about 50 ms later, showed an earlier maturation and has been suggested to reflect early response selection processes in the anterior cingulate. Primary headache patients showed the same component structure and developmental trajectory as healthy subjects without significant influences of differential diagnosis. We conclude that: (1) Brain maturation crucially influences N1b. (2) Two frontal lobe N1 components can be dissociated in their maturational trajectory. (3) Early SMA activation could be elicited by rare auditory stimuli from about 12 years on, allowing fast sensory-motor coupling without previous categorical stimulus classification. (4) Primary headache patients did not differ in their maturation of frontal or temporal contributions to N1b when elicited by moderately loud short tone bursts.