The functional relationship between visual backward masking and prepulse inhibition

This experiment demonstrated a relationship between prepulse inhibition (PPI) of the startle eyeblink and visual backward masking in college students. It was hypothesized that recovery from backward masking effects is due in part to sensory gating, as assessed by auditory and visual PPI. Visual presentations of letters served as targets or visual prepulses in an intermixed session of backward masking and PPI. Backward masking and PPI (both auditory and visual) were assessed at stimulus onset asynchronies of 30, 45, 60, 120, and 150 ms. A repeated-measures regression revealed that there was a relationship between backward masking and PPI for both visual and auditory PPI, with higher levels of PPI being associated with greater recovery from backward masking. The data are consistent with the hypothesis that recovery from backward masking effects is affected by sensory gating acting in part to gate out the interruptive effects of the mask.     

Sensitivity and specificity of auditory steady-state response testing

INTRODUCTION:

The ASSR test is an electrophysiological test that evaluates, among other aspects, neural synchrony, based on the frequency or amplitude modulation of tones.

OBJECTIVE:

The aim of this study was to determine the sensitivity and specificity of auditory steady‐state response testing in detecting lesions and dysfunctions of the central auditory nervous system.

METHODS:

Seventy volunteers were divided into three groups: those with normal hearing; those with mesial temporal sclerosis; and those with central auditory processing disorder. All subjects underwent auditory steady‐state response testing of both ears at 500 Hz and 2000 Hz (frequency modulation, 46 Hz). The difference between auditory steady‐state response‐estimated thresholds and behavioral thresholds (audiometric evaluation) was calculated.

RESULTS:

Estimated thresholds were significantly higher in the mesial temporal sclerosis group than in the normal and central auditory processing disorder groups. In addition, the difference between auditory steady‐state response‐estimated and behavioral thresholds was greatest in the mesial temporal sclerosis group when compared to the normal group than in the central auditory processing disorder group compared to the normal group.

DISCUSSION:

Research focusing on central auditory nervous system (CANS) lesions has shown that individuals with CANS lesions present a greater difference between ASSR‐estimated thresholds and actual behavioral thresholds; ASSR‐estimated thresholds being significantly worse than behavioral thresholds in subjects with CANS insults. This is most likely because the disorder prevents the transmission of the sound stimulus from being in phase with the received stimulus, resulting in asynchronous transmitter release. Another possible cause of the greater difference between the ASSR‐estimated thresholds and the behavioral thresholds is impaired temporal resolution.

CONCLUSIONS:

The overall sensitivity of auditory steady‐state response testing was lower than its overall specificity. Although the overall specificity was high, it was lower in the central auditory processing disorder group than in the mesial temporal sclerosis group. Overall sensitivity was also lower in the central auditory processing disorder group than in the mesial temporal sclerosis group.     

Which People with Specific Language Impairment have Auditory Processing Deficits?

An influential theory attributes developmental disorders of language and literacy to low-level auditory perceptual difficulties. However, evidence to date has been inconsistent and contradictory. We investigated whether this mixed picture could be explained in terms of heterogeneity in the language-impaired population. In Experiment 1, the behavioural responses of 16 people with specific language impairment (SLI) and 16 control listeners (aged 10 to 19 years) to auditory backward recognition masking (ABRM) stimuli and unmasked tones indicated that a subgroup of people with SLI are less able to discriminate between the frequencies of sounds regardless of their rate of presentation. Further, these people tended to be the younger participants, and were characterised by relatively poor nonword reading. In Experiment 2, the auditory event-related potentials (ERPs) of the same groups to unmasked tones were measured. Listeners with SLI tended to have age-inappropriate waveforms in the N1-P2-N2 region, regardless of their auditory discrimination scores in Experiment 1. Together, these results suggest that SLI may be characterised by immature development of auditory cortex, such that adult-level frequency discrimination performance is attained several years later than normal.     

Auditory stream segregation in children with Asperger syndrome

Individuals with Asperger syndrome (AS) often have difficulties in perceiving speech in noisy environments. The present study investigated whether this might be explained by deficient auditory stream segregation ability, that is, by a more basic difficulty in separating simultaneous sound sources from each other. To this end, auditory event-related brain potentials were recorded from a group of school-aged children with AS and a group of age-matched controls using a paradigm specifically developed for studying stream segregation. Differences in the amplitudes of ERP components were found between groups only in the stream segregation conditions and not for simple feature discrimination. The results indicated that children with AS have difficulties in segregating concurrent sound streams, which ultimately may contribute to the difficulties in speech-in-noise perception.     

Abnormal frequency discrimination in children with SLI as indexed by mismatch negativity (MMN)

For several decades, the aetiology of specific language impairment (SLI) has been associated with a central auditory processing deficit disrupting the normal language development of affected children. One important aspect for language acquisition is the discrimination of different acoustic features, such as frequency information. Concerning SLI, studies to date that examined frequency discrimination abilities have been contradictory. We hypothesized that an auditory processing deficit in children with SLI depends on the frequency range and the difference between the tones used. Using a passive mismatch negativity (MMN)-design, 13 boys with SLI and 13 age- and IQ-matched controls (7-11 years) were tested with two sine tones of different frequency (700Hz versus 750Hz). Reversed hemispheric activity between groups indicated abnormal processing in SLI. In a second time window, MMN2 was absent for the children with SLI. It can therefore be assumed that a frequency discrimination deficit in children with SLI becomes particularly apparent for tones below 750Hz and for a frequency difference of 50Hz. This finding may have important implications for future research and integration of various research approaches.     

Time course of auditory masker effects: Tapping the locus of audiovisual integration?

In a focused attention paradigm, saccadic reaction time (SRT) to a visual target tends to be shorter when an auditory accessory stimulus is presented in close temporal and spatial proximity. Observed SRT reductions typically diminish as spatial disparity between the stimuli increases. Here a visual target LED (500 ms duration) was presented above or below the fixation point and a simultaneously presented auditory accessory (2 ms duration) could appear at the same or the opposite vertical position. SRT enhancement was about 35 ms in the coincident and 10 ms in the disparate condition. In order to further probe the audiovisual integration mechanism, in addition to the auditory non-target an auditory masker (200 ms duration) was presented before, simultaneous to, or after the accessory stimulus. In all interstimulus interval (ISI) conditions, SRT enhancement went down both in the coincident and disparate configuration, but this decrement was fairly stable across the ISI values. If multisensory integration solely relied on a feed-forward process, one would expect a monotonic decrease of the masker effect with increasing ISI in the backward masking condition. It is therefore conceivable that the relatively high-energetic masker causes a broad excitatory response of SC neurons. During this state, the spatial audio-visual information from multisensory association areas is fed back and merged with the spatially unspecific excitation pattern induced by the masker. Assuming that a certain threshold of activation has to be achieved in order to generate a saccade in the correct direction, the blurred joint output of noise and spatial audio-visual information needs more time to reach this threshold prolonging SRT to an audio-visual object.     

Pupillary responses and attentional allocation problems on the backward masking task in schizophrenia.

Early visual information processing impairment has consistently been found on the backward masking task in patients with schizophrenia, but the nature of this impairment remains unclear. Pupillometry was used to measure attentional allocation during visual backward masking task performance in patients with schizophrenia (n=16) and nonpsychiatric controls (n=16). The extent of pupil dilation recorded during a cognitive task reflects the processing load placed on the nervous system by the task. Schizophrenia patients detected significantly fewer targets than controls only when the stimulus onset asynchrony (SOA) between targets and masks reached 317 ms. For both groups, peak pupil dilation responses were also significantly larger in the 317 ms SOA condition relative to a no-mask condition, suggesting that the processing load of the 317 SOA masking condition was greater than the no-mask condition. In addition, a principal components analysis of pupillary response waveforms identified time-related factors that appeared to differentially index attentional allocation to targets vs. masks. Patients with schizophrenia showed less dilation than controls on a middle factor that appeared to index attentional allocation to targets, but patients showed greater dilation than controls on a late factor that appeared to index attentional allocation to masks. That is, controls attended more to targets than to masks, but patients attended more to masks than to targets. These findings suggest that masking impairments at SOA intervals greater than 100-200 ms may be due abnormalities in attentional allocation mechanisms.     

弱智儿童听觉中潜伏期反应和40Hz相关电位

目的：对弱智儿童４０Ｈｚ听觉相关电位（４０ＨｚＡＥＲＰ）、听觉中潜伏期反应（ＭＬＲ）和听性脑干反应（ＡＢＲ）检测结果进行比较和评估。方法：在作过ＡＢＲ测试的基础上，对６５例（１３０耳）弱智儿童和３０例（６０耳）正常儿童记录４０ＨｚＡＥＲＰ和ＭＬＲ，对两组各项结果进行比较。结果：弱智组４０ＨｚＡＥＲＰ和ＭＬＲ波形出现率在２０ｄＢ（ｎＨＬ）声强刺激时明显低于正常组（Ｐ＜０．００１）；４０ＨｚＡＥＲＰ反应阈较正常儿童增高（Ｐ＜０．０１）；弱智组ＭＬＲ波潜伏期较正常儿稍延长；ＭＬＲ各波振幅较正常组明显降低（Ｐ＜０．０５）。４０ＨｚＡＥＲＰ检测弱智组的波形出现率、反应阈值等与正常组儿童的差异小于ＡＢＲ。结论：弱智组平均听力较正常儿童差；４０ＨｚＡＥＲＰ在评价弱智儿童听力时敏感性比ＡＢＲ高，更能检测出患者存在的低频残余听力     

A signal detection study of the Colavita visual dominance effect

When presented with auditory, visual, or bimodal audiovisual stimuli in a speeded detection/discrimination task, participants fail to respond to the auditory component of the bimodal targets significantly more often than they fail to respond to the visual component. Signal detection theory (SDT) was used to explore the contributions of perceptual (sensitivity shifts) and decisional (shifts in response criteria) factors to this effect, known as the Colavita visual dominance effect. Participants performed a version of the Colavita task that had been modified to allow for SDT analyses. The participants had to detect auditory and visual targets (presented unimodally or bimodally) at their individually determined 75% detection thresholds. The results showed a significant decrease in participants’ sensitivity to auditory stimuli when presented concurrently with visual stimuli (in the absence of any significant change in their response criterion), suggesting that Colavita visual dominance does not simply reflect a decisional effect, but can be explained, at least in part, as a truly perceptual phenomenon. The decrease in sensitivity (to auditory stimuli) may be attributable to the exogenous capture of participants’ attention by the visual component of the bimodal target, thus leaving fewer attentional resources for the processing of the auditory stimulus. The reduction in auditory sensitivity reported here may be considered an example of crossmodal masking.     

儿童感音神经性聋听觉稳态诱发反应阈与听性脑干反应阈比较

目的研究听觉稳态诱发反应(ASSR)和听性脑干反应(ABR)阈与纯音听阈的差别和相关性。方法选择74例儿童感音神经性聋患者(118耳)分别进行ASSR、ABR和电测听检查,比较ASSR、ABR反应阈及纯音听阈,同时就ASSR、ABR反应阈与纯音听阈进行相关性分析。结果 ASSR和ABR反应阈与纯音听阈均有良好的相关性。ABR的反应阈与纯音听阈阈值接近,而ASSR反应阈与纯音听阈间差值较大。ASSR反应阈与纯音听阈间的相关性要优于ABR反应阈与纯音听阈间的相关性。结论 ASSR和ABR均为较好的评估行为听阈的客观测听方法。     

Speech and non-speech processing in children with phonological disorders: an electrophysiological study

OBJECTIVE:

To determine whether neurophysiological auditory brainstem responses to clicks and repeated speech stimuli differ between typically developing children and children with phonological disorders.

INTRODUCTION:

Phonological disorders are language impairments resulting from inadequate use of adult phonological language rules and are among the most common speech and language disorders in children (prevalence: 8 ‐ 9%). Our hypothesis is that children with phonological disorders have basic differences in the way that their brains encode acoustic signals at brainstem level when compared to normal counterparts.

METHODS:

We recorded click and speech evoked auditory brainstem responses in 18 typically developing children (control group) and in 18 children who were clinically diagnosed with phonological disorders (research group). The age range of the children was from 7‐11 years.

RESULTS:

The research group exhibited significantly longer latency responses to click stimuli (waves I, III and V) and speech stimuli (waves V and A) when compared to the control group.

DISCUSSION:

These results suggest that the abnormal encoding of speech sounds may be a biological marker of phonological disorders. However, these results cannot define the biological origins of phonological problems. We also observed that speech‐evoked auditory brainstem responses had a higher specificity/sensitivity for identifying phonological disorders than click‐evoked auditory brainstem responses.

CONCLUSIONS:

Early stages of the auditory pathway processing of an acoustic stimulus are not similar in typically developing children and those with phonological disorders. These findings suggest that there are brainstem auditory pathway abnormalities in children with phonological disorders.     

Lateralisation of auditory processing in Down syndrome: a study of T-complex peaks Ta and Tb

It has long been argued that abnormal cerebral lateralisation might underlie the language problems that characterise Down syndrome, but to date only behavioural evidence has been provided. We used the auditory event-related potentials Ta and Tb of the T-complex to investigate lateralised processing of speech (vowels) and non-speech (simple and complex tones) sounds in children with Down syndrome and age-matched typically developing children. We also explored associations with speech and language abilities. Although changes in the Ta and Tb in response to increases in stimulus complexity and 'speechness' were similar across group, the Tb peak was delayed in children with Down syndrome across conditions. In addition, marked differences in the patterns of lateralisation of Ta latency and Tb amplitude were observed in children with Down syndrome, in response to both speech and non-speech sounds. No associations were found between Ta and Tb characteristics and speech and language abilities in children with DS.     

Auditory evoked potentials: predicting speech therapy outcomes in children with phonological disorders

OBJECTIVES:

This study investigated whether neurophysiologic responses (auditory evoked potentials) differ between typically developed children and children with phonological disorders and whether these responses are modified in children with phonological disorders after speech therapy.

METHODS:

The participants included 24 typically developing children (Control Group, mean age: eight years and ten months) and 23 children clinically diagnosed with phonological disorders (Study Group, mean age: eight years and eleven months). Additionally, 12 study group children were enrolled in speech therapy (Study Group 1), and 11 were not enrolled in speech therapy (Study Group 2). The subjects were submitted to the following procedures: conventional audiological, auditory brainstem response, auditory middle-latency response, and P300 assessments. All participants presented with normal hearing thresholds. The study group 1 subjects were reassessed after 12 speech therapy sessions, and the study group 2 subjects were reassessed 3 months after the initial assessment. Electrophysiological results were compared between the groups.

RESULTS:

Latency differences were observed between the groups (the control and study groups) regarding the auditory brainstem response and the P300 tests. Additionally, the P300 responses improved in the study group 1 children after speech therapy.

CONCLUSION:

The findings suggest that children with phonological disorders have impaired auditory brainstem and cortical region pathways that may benefit from speech therapy.     

Electrophysiologic assessment of central auditory processing by auditory brainstem responses in children with autism spectrum disorders

In addition to aberrant features in the speech, children with Autism Spectrum Disorder (ASD) may present unusual responses to sensory stimuli, especially to auditory stimuli. We investigated the auditory ability of children with ASD by using Auditory Brainstem Responses (ABR) as they can directly judge both hearing status and the integrity of auditory brainstem pathways. One hundred twenty-one children (71: ASD; M 58/ F 13, mean age; 41.8 months, 50: control group; M 41/ F 9, mean age; 38 months) were included in the study. As compared with the values in the control group, the latency of wave V, wave I-V, and wave III-V inter-peak latencies were significantly prolonged (p<0.05) in the ASD group. The findings indicate that children with ASD have a dysfunction or immaturity of the central auditory nervous system. We suggest any children with prolonged III-V inter-peak latencies, especially high functioning children should be further evaluated for central auditory processing to set up a more appropriate treatment plan.     

Auditory neuropathy in streptozotocin-induced diabetic mouse

An investigation of the mechanism of damage to the peripheral nervous system and central nervous system in diabetes mellitus (DM) is highly important in current neurological research. Auditory neuropathy is a hearing disorder in which the auditory brainstem evoked potential is absent or severely abnormal. This study investigated auditory neuropathy caused by streptozotocin in mouse model. In order to assess diabetic auditory neuropathy, we evaluated auditory brainstem response (ABR) for the evaluation of sensorineural function in peripheral auditory nerve. Auditory middle latency response (AMLR) was employed to assess the middle response in the midbrain. STZ groups significantly increased the absolute latencies IV and the interpeak latencies I-III and I-IV of ABR compared with STZ 0 group. Pa latency of AMLR also significantly increased in proportion to STZ dosage. Taken together, our results demonstrate that STZ-induced DM may impair the auditory pathway from peripheral auditory nerve to midbrain in the mouse model. We suggest that the STZ-induced diabetic mouse model may be useful for the evaluation of auditory pathway impairment by using ABR and AMLR tests.     

Audio–vocal system regulation in children with autism spectrum disorders

Do children with autism spectrum disorders (ASD) respond similarly to perturbations in auditory feedback as typically developing (TD) children? Presentation of pitch-shifted voice auditory feedback to vocalizing participants reveals a close coupling between the processing of auditory feedback and vocal motor control. This paradigm was used to test the hypothesis that abnormalities in the audio–vocal system would negatively impact ASD compensatory responses to perturbed auditory feedback. Voice fundamental frequency (F ₀) was measured while children produced an /a/ sound into a microphone. The voice signal was fed back to the subjects in real time through headphones. During production, the feedback was pitch shifted (?100 cents, 200 ms) at random intervals for 80 trials. Averaged voice F ₀ responses to pitch-shifted stimuli were calculated and correlated with both mental and language abilities as tested via standardized tests. A subset of children with ASD produced larger responses to perturbed auditory feedback than TD children, while the other children with ASD produced significantly lower response magnitudes. Furthermore, robust relationships between language ability, response magnitude and time of peak magnitude were identified. Because auditory feedback helps to stabilize voice F ₀ (a major acoustic cue of prosody) and individuals with ASD have problems with prosody, this study identified potential mechanisms of dysfunction in the audio–vocal system for voice pitch regulation in some children with ASD. Objectively quantifying this deficit may inform both the assessment of a subgroup of ASD children with prosody deficits, as well as remediation strategies that incorporate pitch training.     

Noise-induced tinnitus: auditory evoked potential in symptomatic and asymptomatic patients

OBJECTIVES:

We evaluated the central auditory pathways in workers with noise-induced tinnitus with normal hearing thresholds, compared the auditory brainstem response results in groups with and without tinnitus and correlated the tinnitus location to the auditory brainstem response findings in individuals with a history of occupational noise exposure.

METHOD:

Sixty individuals participated in the study and the following procedures were performed: anamnesis, immittance measures, pure-tone air conduction thresholds at all frequencies between 0.25–8 kHz and auditory brainstem response.

RESULTS:

The mean auditory brainstem response latencies were lower in the Control group than in the Tinnitus group, but no significant differences between the groups were observed. Qualitative analysis showed more alterations in the lower brainstem in the Tinnitus group. The strongest relationship between tinnitus location and auditory brainstem response alterations was detected in individuals with bilateral tinnitus and bilateral auditory brainstem response alterations compared with patients with unilateral alterations.

CONCLUSION:

Our findings suggest the occurrence of a possible dysfunction in the central auditory nervous system (brainstem) in individuals with noise-induced tinnitus and a normal hearing threshold.     

Dissociation of sensitivity and response bias in children with attention deficit/hyperactivity disorder during central auditory masking

Forty-three children (ages 7.0-14.5 years old) with and without attention deficit/hyperactivity disorder (ADHD), combined type had thresholds for detection of a 500-Hz pure tone estimated with and without a noise masker in the contralateral ear. The ear receiving the signal in the masked condition was varied randomly. A single-interval maximum-likelihood method estimated thresholds and false-alarm rate. Whereas the increase in threshold in children with ADHD in the presence of contralateral masking was comparable with controls, the increase in false-alarm rate was significantly greater. This dissociation between changes in sensitivity and response bias in the presence of masking noise supports suggestions that children with ADHD have difficulty inhibiting maladaptive responses and indicates that this deficit is quantifiable using psychoacoustic methods.     

Forward and backward visual masking in schizophrenia: influence of age

BACKGROUND: Visual masking tasks assess the earliest stages of visual processing. This study was conducted to address: (1) whether schizophrenia patients show masking deficits after controlling for sensory input factors; (2) whether patients have relatively intact forward masking (when the mask precedes the target) compared with backward masking (when the mask follows the target); and (3) whether the masking deficits in schizophrenia reflect an accelerated age-related decline in performance. METHOD: A staircase method was used to ensure that the unmasked target identification was equivalent across subjects to eliminate any confounding due to differences in discrimination of simple perceptual inputs. Three computerized visual masking tasks were administered to 120 schizophrenia patients (ages 18-56) and 55 normal comparison subjects (ages 19-54) under both forward and backward masking conditions. The tasks included: (1) locating a target; (2) identifying a target with a high-energy mask; and (3) identifying a target with a low-energy mask. RESULTS: Patients showed deficits across all three masking tasks. Interactions of group by forward versus backward masking were not significant, suggesting that deficits in forward and backward masking were comparable. All three conditions showed an age-related decline in performance and rates of decline were comparable between patients and controls. Two of the masking conditions showed increased rates of decline in backward, compared to forward, masking. CONCLUSIONS: We found age-related decline in performance that was comparable for the two groups. In addition, we failed to find evidence of a relative sparing of forward masking in schizophrenia. These results suggest that: (1) early visual processing deficits in schizophrenia are not due to a simple perceptual input problem; (2) sustained channels are involved in the masking deficit (in addition to transient channels); and (3) for the age range in this study, these deficits in schizophrenia are not age-related.     

Auditory sensory memory and language abilities in former late talkers: A mismatch negativity study

The present study investigated whether (a) a reduced duration of auditory sensory memory is found in late talking children and (b) whether deficits of sensory memory are linked to persistent difficulties in language acquisition. Former late talkers and children without delayed language development were examined at the age of 4 years and 7 months using mismatch negativity (MMN) with interstimulus intervals (ISIs) of 500 ms and 2000 ms. Additionally, short‐term memory, language skills, and nonverbal intelligence were assessed. MMN mean amplitude was reduced for the ISI of 2000 ms in former late talking children both with and without persistent language deficits. In summary, our findings suggest that late talkers are characterized by a reduced duration of auditory sensory memory. However, deficits in auditory sensory memory are not sufficient for persistent language difficulties and may be compensated for by some children.