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PubMed2002

Electrocochleography in auditory neuropathy.

Auditory neuropathy (AN) is a disorder characterized by the absence or the severe impairment of the auditory brainstem responses (ABRs) together with the preservation of otoacoustic emissions and/or cochlear microphonic (CM). We recorded transtympanic electrocochleography (ECohG) evoked by 0.1 ms clicks in one young adult and in four children having distortion product otoacoustic emissions and absent ABRs. In all but one patient CM and summating potential (SP) were present with normal threshold, and their amplitudes appeared comparable to or higher than the values obtained from subjects with normal hearing. The compound action potential (CAP) was absent in two patients while in one subject CM and SP were followed by a highly desynchronized neural activity. A broad CAP was found in two children and the threshold appeared clearly elevated in one of them, while it showed only a mild elevation in the other. No correlation was found between CAP and behavioral thresholds. These results suggest that ECohG can be useful in AN diagnoses since it is the only reliable tool in evaluating the auditory peripheral function in the presence of a desynchronized ABR.

Action Potentials↗
PubMed2000

Effect of stimulation parameters on electrically evoked auditory brainstem responses.

It is evident that the conventional technique for cochlear implant adjustment is not suitable for children in their first years of life. In order to find a solution to this problem, the possibility of electrically evoked auditory brainstem response (EABR) recording was investigated. EABRs were recorded in 9 patients with the Nucleus multichannel cochlear implant. The main problems that have to be solved during EABR recording in cochlear implantees are: i) EABR distortion due to the stimulus artefact: and ii) difference in the stimulus presentation rate during EABR registration (low pulse rate) and conventional psychophysical threshold estimation (high pulse rate) in cochlear implant patients. The influence of stimulus artefact on the recording results was minimized by setting the implant to the widest amplifier frequency band and by zeroing the initial segment containing the stimulus artefact with subsequent zero-phase digital filtering. The dependence of the EABR amplitude and latency on the stimulus intensity, width, electrode location and interstimulus interval was investigated. It was concluded that despite the difference revealed between absolute values of EABR thresholds and psychophysical threshold levels, it is possible to calculate implant adjustment parameters based on the EABR data with the proper correction applied.

Acoustic Stimulation↗
PubMed2006

Hyperacusis in Williams syndrome: characteristics and associated neuroaudiologic abnormalities.

BACKGROUND: Hyperacusis and phonophobia are common, debilitating symptoms in Williams syndrome (WS), yet little is known about their underlying audiologic and neurologic processes. METHODS: The mothers of 49 subjects with WS were asked to complete the Hyperacusis Screening Questionnaire. Subjects with reported hyperacusis and sufficient developmental capacity underwent comprehensive audiological and brain auditory evoked response (BAER) testing. Findings were compared with those from pair-matched typically developing control subjects. RESULTS: Forty-one of the 49 children with WS (84%) had hyperacusis of moderate to severe degree, which began in infancy. Of these, 21 (mean age 15.8 +/- 5.5 years) were quantitatively tested. Subjects with WS reported discomfort at sound intensities on average 20 dB lower than control subjects. Pure-tone audiometry and distortion products otoacoustic emission test revealed a high-frequency cochlear hearing loss. An absence of ipsilateral acoustic reflex responses to maximum stimulation was significantly more common in the subjects with WS than controls. On BAER testing, the WS group had a significant prolongation in wave I latency. CONCLUSIONS: Hyperacusis in Williams syndrome (WS) is associated with a high-frequency hearing loss resembling the configuration of noise-induced hearing loss. The hyperacusis and hearing loss in WS may stem from a deficiency in the acoustic reflex resulting from auditory nerve dysfunction. Additional mechanisms that may mediate hyperacusis in WS and should be evaluated in future studies include recruitment, malformation of the facial canal, and haploinsufficiency of the elastin gene.

Acoustic Stimulation↗
PubMed1991

Altered susceptibility of 2f1-f2 acoustic-distortion products to the effects of repeated noise exposure in rabbits.

Hearing sensitivity and the generation of acoustic-distortion products at 2f1-f2 were examined systematically in behaviorally trained rabbits, before, during, and following regular exposure to a 95-dB SPL octave band of noise, centered at 1 kHz. During the exposure period, the octave-band noise was interrupted once every 24 h in order to monitor the progressive loss in auditory function using tests of behavioral threshold and distortion-product otoacoustic emissions (DPOAEs). When low-frequency DPOAEs from 1-4 kHz diminished to noise-floor levels, i.e., when their amplitudes were reduced by about 20-30 dB, the exposure was terminated. Subsequent recovery of behavioral thresholds and DPOAE amplitudes and detection 'thresholds' was evaluated at regular intervals over a 3-week post-exposure period. Following the recovery period, the rabbits again received the identical exposure/recovery treatment until a permanent 10 dB or greater loss in DPOAE amplitudes was achieved for any point of measurement between 2-10 kHz. The primary result was that the number of days of overstimulation required for rabbits to reach the criterion loss in DPOAE amplitudes increased for each successive exposure session. In addition, DPOAEs accurately tracked the frequency pattern described by the behavioral threshold shifts during both the development and recovery stages of exposure.

Animals↗
PubMed2005

Stimulus selectivity of figural aftereffects for faces.

Viewing a distorted face induces large aftereffects in the appearance of an undistorted face. The authors examined the processes underlying this adaptation by comparing how selective the aftereffects are for different dimensions of the images including size, spatial frequency content, contrast, and color. Face aftereffects had weaker selectivity for changes in the size, contrast, or color of the images and stronger selectivity for changes in contrast polarity or spatial frequency. This pattern could arise if the adaptation is contingent on the perceived similarity of the stimuli as faces. Consistent with this, changing contrast polarity or spatial frequency had larger effects on the perceived identity of a face, and aftereffects were also selective for different individual faces. These results suggest that part of the sensitivity changes underlying the adaptation may arise at visual levels closely associated with the representation of faces.

Adaptation, Psychological↗
PubMed2000

Consequences of outer hair cell damage for otoacoustic emissions and audio-vocal feedback in the mustached bat.

The cochlea of the mustached bat is adapted to process ultrasonic echolocation signals. To assess the involvement of active sound amplification by outer hair cells in high-frequency hearing and in audio-vocal interaction, selective hair cell damage was induced by the antibiotic Amikacin. Amikacin preferentially damaged the first row of outer hair cells in the basal cochlear turn. The cochlear regions coding for the second-harmonic constant-frequency component of the echolocation call (CF2) at 61 kHz and for frequencies between 75 and 100 kHz were the most affected. This was reflected in an increase of mechanical thresholds obtained by measuring distortion-product otoacoustic emissions. During initial periods of minor hair cell damage, when thresholds had deteriorated by less than 40 dB, a sharp, mechanical, cochlear resonance that is responsible for enhanced tuning to 61 kHz was still measurable as a stimulus-frequency otoacoustic emission and its frequency decreased by 350 Hz. The persistence of the resonance suggests that passive structures like the tectorial or basilar membrane are important for generation of the resonance. Behaviorally, the bats reacted to the change in cochlear micromechanics with a decrease of their CF2 frequency by 360 Hz. After larger hair cell damage, when the cochlear resonance had disappeared, the bats vocalized only sparsely and the CF2 frequency increased by up to 2 kHz, which may correspond to a state without audiovocal feedback. This indicates that audio-vocal feedback in the nondamaged animal works to lower the call frequency.

Animals↗
PubMed2002

Effects of anesthesia on efferent-mediated adaptation of the DPOAE.

Distortion product otoacoustic emissions (DPOAE) adapt after primary tone onset, with an approximately 100 ms time constant, due to feedback effects of medial olivocochlear (MOC) activity elicited by the primary tones. We tracked DPOAE postonset adaptation as a metric of MOC reflex strength, before during and after induction of anesthesia in guinea pigs. Reflex strength was significantly diminished by the barbiturate/neuroleptic anesthesia most commonly used in this species. The MOC reflex recovered more slowly than toe-pinch or startle reflexes, correlating better with recovery of general mobility. When individual anesthetic agents were assessed, the barbiturate (pentobarbital) significantly diminished MOC reflex strength, whereas fentanyl or droperidol did not. These results suggest that previous studies using anesthetized preparations may have underestimated the magnitude of sound-evoked responses in the OC pathway.

Adaptation, Physiological↗
PubMed1997

Cognitive distortions in sex offenders: an integrative review.

Clinicians and researchers have noted that maladaptive beliefs and distorted thinking play an important role in facilitating or justifying sexual offenses. There have been a number of attempts to describe the nature of these beliefs and to develop ways of measuring them, but in the absence of any integrating theory. We suggest that an understanding of the cognitive processes underlying the initiation, maintenance, and justification of sexual offending is a vital prerequisite to the development of successful treatment programs. In this paper, we use a social cognition framework to review the literature on the role of cognition in sexual offending. Pertinent research in the sexual offending domain, specifically cognitive products, information processing, cognitive change, and the impact of affective and motivational factors on cognitive processes, is described and related to the social cognitive approach. Implications for future research and clinical practice are discussed in light of the major issues and problems highlighted in our review.

Adult↗
PubMedDate not supplied

Acoustic distortion products (ADP) from the ears of term infants and young adults using low stimulus levels.

It has been shown previously that relatively low stimulus levels (L1 = 55, L2 = 40 dB SPL) elicit recordable levels of ADP from healthy adult ears (Gaskill and Brown, 1990). We have used the same stimulus levels in healthy term infants within 6 days of birth. The results from the 38 infants who provided data from both ears (from a total of 66 attempted) are reported here. The data were compared with those from 12 adults aged 20 to 30 years with normal audiometric thresholds. ADP was measured across frequency with f2 (the high frequency tone) between 1 and 8 kHz (infants) and 0.5 kHz and 8 kHz (adults) and f1 (the low frequency tone) determined by f2/1.225. ADP was also measured at a range of different stimulus frequency separations. The mean level of ADP was higher in infant than in adult ears but this difference was not significant. The f2/f1 ratio of approximately 1.2 which has been widely adopted for use in adults is also an appropriate frequency separation for term infants.

Acoustic Stimulation↗
PubMed2001

Simultaneous exposure to ethyl benzene and noise: synergistic effects on outer hair cells.

The effects on hearing of simultaneous exposure to the ototoxic organic solvent ethyl benzene and broad-band noise were evaluated in rats. The effects of three ethyl benzene concentrations (0, 300 or 400 ppm) and three noise levels (95 or 105 dB(lin) SPL or background noise at 65 dB(lin) SPL) and all their combinations were investigated for a 5 day exposure at 8 h/day. Distortion product otoacoustic emissions and compound action potentials were affected after 105 dB noise alone, and after 105 dB noise in combination with ethyl benzene (300 and 400 ppm). However, the amount of loss for these combinations did not exceed the loss for 105 dB noise alone. Outer hair cell (OHC) loss after exposure to 300 ppm ethyl benzene was located in the third row of OHCs. At 400 ppm, the loss spread out to the second and first row of OHCs. Noise alone hardly affected the OHC counts except for a minor loss in the first row of OHCs after 105 dB SPL. Noise at 105 dB in combination with ethyl benzene at 300 and 400 ppm, however, showed OHC loss greater than the sum of the losses induced by noise and ethyl benzene alone.

Action Potentials↗
PubMed2003

The role of proprioception in action recognition.

This study aimed at evaluating the role of proprioception in the process of matching the final position of one's limbs with an intentional movement. Two experiments were realised with the same paradigm of conscious recognition of one's own limb position from a distorted position. In the first experiment, 22 healthy subjects performed the task in an active and in a passive condition. In the latter condition, proprioception was the only available information since the central signals related to the motor command were likely to be absent. The second experiment was realised with a deafferented patient who suffers from a complete haptic deafferentation, including loss of proprioception. The results first argue in favour of a dominant role of proprioception in action recognition, but they also stress the possible role of central signals. The process of matching the final position of one's limbs with an intended movement and thus of action recognition would be achieved through a comparison process between the predicted sensory consequences of the action, which are stored in its internal model, and the actual sensory consequences of that action.

Adult↗
PubMed2003

Effects of chronic exposure of electromagnetic fields from mobile phones on hearing in rats.

OBJECTIVE: Little attention has been paid to the effects of electromagnetic field (EMF) of mobile phones on hearing. The aim of this study is to investigate the effects of chronic exposure to EMF emitting from mobile phones on the inner ear of adult and developing rats using distortion product otoacoustic emissions (DPOAEs). METHODS: EMF of mobile phones exposure was scheduled according to a sham-exposure controlled experimental design. Every day seven of 14 adult and four newborn rats were exposed to 1-h mobile phone EMF for 30 days, while the other seven adult rats were assigned to control group. DPOAEs were measured in both groups before and after the chronic exposure to EMF. The newborn rats were tested following similar exposure beginning on the 2nd day after birth. RESULTS: No measurable EMF associated changes in DPOAEs either in adult or developing rat inner ears were determined (P>0.05). CONCLUSION: It was concluded that chronic exposure of EMF, as long as 30 days 1 h per day, emitting from a mobile phone did not cause any hearing deterioration in adult and developing rats, at least at outer and middle ear and cochlear levels.

Animals↗
PubMed2004

Anton Raederscheidt's distorted self-portraits and their significance for understanding balance in art.

Following a right cerebral stroke, the German artist Anton Raederscheidt produced a remarkable series of self-portraits that depicted his severe visual neglect and gradual recovery. These distorted images, like those drawn by others with this disorder, inform us about lateral balance in art and why it is common in the art of cultures separated in time and space. After describing how artists in various cultures have employed lateral balance, I present Arnheim's view that this aspect of art is the result of visual forces generated by the brain. Following a brief history of visual neglect, I present evidence that this disorder provides us with clues to the origin of the visual forces responsible for lateral balance in art. The relevant brain mechanisms control exploration of visual space by integrating orienting movements with visual spatial information. The prevalence of lateral balance in art becomes understandable when we consider that these brain mechanisms evolved to promote survival in our vertebrate ancestors. I end with a speculative neurological account of the aesthetics of lateral balance--why it is pleasing and its absence is displeasing.

Famous Persons↗
PubMed2001

The size-tuning of the face-distortion after-effect.

Recently, Webster and MacLin demonstrated a face-distortion after-effect (FDAE) for both upright and inverted faces: adaptation to a distorted face makes a normal face appear distorted in the direction opposite to the adapting direction. Neurophysiological studies (e.g. Experimental Brain Research 65 (1986) 38) show that face-selective neurons in the superior temporal sulcus (STS) are remarkably size-invariant in their responses. If the site of adaptation underlying the FDAE is the homologous neuron population in human vision, then the FDAE should also be highly tolerant to changes in size between adapting and test faces. Here, we test this prediction. Observers were adapted to distorted upright/inverted faces of three different sizes (3.3 degrees x 3.7 degrees, 6.6 degrees x 7.5 degrees, and 13.1 degrees x 14.8 degrees ). For adapting faces of all three sizes, observers adjusted test faces of all three sizes until they appeared normal. Significant FDAEs were observed in all conditions. For both upright and inverted faces, FDAEs were approximately twice as strong when adapting and test faces were the same size than when they differed by even a single octave in size. The magnitudes of FDAEs were comparable for upright and inverted faces. The larger FDAEs for same-size adapting and test faces suggest that part of the FDAE derives from a neuron population with narrow size-tuning. However, the significant FDAEs obtained for adapting and test images differing by two octaves implicate a different neuron population with broad size-tuning, possibly the human homolog of the face-selective neuron population in monkey STS.

Afterimage↗
PubMed1999

Preference judgments of artificial processed and hearing-aid transduced speech.

In order to assess the relative importance of various signal processing algorithms and distortions on hearing-aid preference, male and female speech was manipulated in a number of ways and subsequently presented to normal-hearing and hearing-impaired subjects (the latter having a mild sensorineural high-frequency hearing loss). Signal manipulations were artificial (e.g., filtering, compression, peak clipping, or adding noise) or were actual dummy-head recordings of five different hearing aids. Listeners judged the sounds in a pairwise-comparison format. Their task was to indicate the "hearing aid" they would prefer assuming they had to wear it all day. The data were analyzed with multidimensional scaling techniques; Principal Components Analysis revealed that the first two dimensions on which preference judgments were based, can be interpreted as (1) intelligibility or clarity, and (2) distinction between signal distortion and added background distortion. Furthermore, the results showed that normal-hearing subjects generally preferred the original signal, whereas hearing-impaired subjects were inclined to choose the signals with a high-frequency emphasis. Severe band-pass filtering or low-frequency emphasis were disliked, as was to be expected. Surprisingly, however, a soft background noise (S/N ratio of 25 dB) was often among the least preferred of all signals. The differences in preference between the five hearing aids were small, but consistent. For hearing-impaired subjects, hearing-aid ordering could be accounted for by the amount of low-frequency cutoff; for normal-hearing subjects both high- and low-frequency cutoff played a role. Results of a retest experiment with normal-hearing subjects, about one year later, showed that subjects' criteria remain remarkably stable.

Adolescent↗
PubMed1987

Body image distortion in non-eating disordered women and men.

This study of body image perception in 100 non-eating disordered women and men demonstrates that overperception of body widths, whilst accurately perceiving a neutral object, is not restricted to populations with eating disorders, nor is it peculiar to women. Men consistently overestimated body widths to the same extent as female subjects. Overall, 84% of women and 52% of men wished to weigh less. Considering those subjects within the 10% range of Mean Matched Population Weight (MMPW), men wished to be 0.75 kg heavier, whilst women at MMPW wished to weigh 3.25 kg less. For women, the subjects who were most satisfied with their actual weight were those who were well below MMPW. There is a tendancy that the greater the deviation of weight from normal, in either direction, the greater the degree of body width overestimation. These results suggest that the overperception of body width is more related to current weight than to concern about weight and shape, or to the presence or absence of an eating disorder. They question the use of empirical body size estimation measurement in eating disordered populations.

Adult↗
PubMed2002

A multifrequency method for determining cochlear efferent activity.

A test based on measures of distortion-product otoacoustic emissions (DPOAEs) was developed in lightly anesthetized guinea pigs and alert rabbits to assess the effective activation or functional "strength" of the cochlear efferent system. The multifrequency method described here used the DP-gram frequency function to evaluate the fast component of the olivocochlear adaptive effect on DPOAE levels over a 2-octave frequency range. An estimate of any concurrent muscle activation was also determined over the identical frequency range by monitoring the levels of the eliciting f1 primary tone throughout its duration. The acoustic reflex, as measured by this f1 level constancy test, did not appear to contribute to the average efferent strength of sedated guinea pigs, but the acoustic reflex did contribute to the average "efferent" strength of awake rabbits. Hence, the average efferent effect in alert rabbits is contaminated by the acoustic reflex, which confounds its interpretation.

Acoustic Stimulation↗
PubMed2001

Effect of inner and outer hair cell lesions on electrically evoked otoacoustic emissions.

When the cochlea is stimulated by a sinusoidal current, the inner ear emits an acoustic signal at the stimulus frequency, termed the electrically evoked otoacoustic emission (EEOAE). Recent studies have found EEOAEs in birds lacking outer hair cells (OHCs), raising the possibility that other types of hair cells, including inner hair cells (IHCs), may generate EEOAEs. To determine the relative contribution of IHCs and OHCs to the generation of the EEOAE, we measured the amplitude of EEOAEs, distortion product otoacoustic emissions (DPOAEs), the cochlear microphonic (CM) and the compound action potential (CAP) in normal chinchillas and chinchillas with IHC lesions or IHC plus OHC lesions induced by carboplatin. Selective IHC loss had little or no effect on CM amplitude and caused a slight reduction in mean DPOAE amplitude. However, IHC loss resulted in a massive reduction in CAP amplitude. Importantly, selective IHC lesions did not reduce EEOAE amplitude, but instead, EEOAE amplitude increased at high frequencies. When both IHCs and OHCs were destroyed, the amplitude of the CM, DPOAE and EEOAE all decreased. The increase in EEOAE amplitude seen with IHC loss may be due to (1) loss of tonic efferent activity to the OHCs, (2) change in the mechanical properties of the cochlea or (3) elimination of EEOAEs produced by IHCs in phase opposition to those from OHCs.

Action Potentials↗