Auditory Processing Deficits Research Articles

O2.7. CAN THEY HEAR IT? DO PATIENTS WITH AUDITORY VERBAL HALLUCINATIONS HAVE AUDITORY PROCESSING DEFICITS?

BackgroundIt has been well established for over half a century that patients with a diagnosis of schizophrenia have auditory processing deficits. More recently, there has been a small body of work that has suggested patients with a history of auditory hallucinations have particularly pertinent auditory processing deficits, with the importance of pitch perception being noted in a single study. This current body of work has systematically investigated whether auditory perception, using a tone detection task, are related to auditory verbal hallucinations (AVH).MethodsFour studies will be presented each of which used a tone detection task that manipulated pitch, with the study 1 also have a tone duration manipulation.ResultsStudy 1 compared 15 AVH with 15 non-AVH patients with schizophrenia with 34 healthy controls, AVH patients demonstrated the greatest impairments on pitch and tone duration deficits compared to the other two groups. Study 2 compared 99 patients with schizophrenia (65 with a history of AVH and 34 without) with 95 healthy controls and confirmed pitch deficits in schizophrenia, specifically those with AVH. Study 3 established in 100 healthy controls that unusual experiences or auditory hallucination proneness were significantly correlated to pitch perception performance. Lastly, study 4 demonstrated that relatives of patients with schizophrenia also showed a significant correlation between usual experiences and pitch perception.DiscussionThis research indicates auditory processing deficits are a core feature of AVH in schizophrenia, and potentially represent an endophenotype for AVH. The authors will discuss a potential cognitive model which explains the relationship between AVH and pitch perception. There are clear translational elements to this research, and we suggest there might be some utility in using auditory training as an intervention to reduce the impact of AVH.

F173. PITCH AND DURATION MISMATCH NEGATIVITY, AUDITORY CORTEX GRAY MATTER, AND PRODROMAL ROLE FUNCTIONING IN THE FIRST EPISODE SCHIZOPHRENIA SPECTRUM

BackgroundPrimary auditory cortex, contained within Heschl’s gyrus, is implicated auditory processing deficits and auditory verbal hallucinations in schizophrenia. Previously we showed a pathological correlation between the magnitude of the pitch-deviant mismatch negativity (pMMN) response during a passive auditory task and reductions in gray matter volume in Heschl’s gyrus in subjects with first hospitalized for schizophrenia. The aim of this study was to replicate this finding, examine duration-deviant mismatch negativity (dMMN) and gray matter correlations, and to examine pre-psychosis role functioning, in a first episode psychosis sample within the schizophrenia-spectrum.MethodsParticipants included 40 first episode schizophrenia subjects (FESz) and 40 healthy controls (HC) matched for age, parental socioeconomic status, IQ, sex, and handedness. For MMN extracted from the EEG, standard tones were presented repeatedly (1 kHz, 75 dB, 50 ms pips, 5 ms rise/fall times, 330 ms SOA) with an occasional pitch deviant (1.2 kHz, 10% of trials) or duration deviant (100 ms, 10% of trials) interspersed. pMMN and dMMN were measured from subtraction waveforms as the average voltage within a 100-ms group averaged peak window at Fz. Role functioning was measured with the Cornblatt Global Functioning: Role scale. A subset of 28 FESz and 28 matched HC underwent structural MRI. High-resolution T1-weighted structural MRI data (3T) were acquired for each subject. Freesurfer was used to segment white matter, gray matter, and pial surfaces. Left and right Heschl’s gyri were manually edited regions of interest, and gray matter volumes determined.ResultsDespite a lack of pMMN or dMMN reduction at the group level in FESz, both measures were pathologically correlated with role functioning in the year prior to hospitalization. In FESz, smaller pMMN at Fz was associated with poorer role functioning in the year prior to psychosis (rho= -.35, p =.03). Similar associations were observed for dMMN (rho= -.41, p <.01). Furthermore, in the subset of FESz with sMRI, smaller pMMN at Fz was associated with less total gray matter volume in left Heschl’s gyrus (TGMV) (rho= -.40, p =.03) but not right. Similar associations were observed for dMMN (rho= -.47, p .01). As well, role functioning and auditory cortex gray matter volumes were not correlated in FESz. There were no significant correlations within HC.DiscussionAlthough pMMN and dMMN are not reduced at the group level, the size of both are associated with impaired functioning prior to psychosis and reduced gray matter volume of left hemisphere Heschl’s gyrus, containing primary and secondary auditory cortices. Thus, pMMN and dMMN although not sufficient as biomarkers of disease presence, are suitable as reliable biomarkers of disease progression. Presumably, poorer role functioning and less gray matter reflect more of the pre-psychosis progressive pathological process thought to occur in the prodromal phase of psychosis. Hence, pMMN and dMMN are likely to serve as sensitive and robust outcome measures for therapeutic interventions and to guide treatment strategies in the prodrome and during early psychosis.

Difficulty hearing in noise: a sequela of concussion in children

ABSTRACTObjective: Concussions can result in auditory processing deficits even in the absence of hearing loss. In children and adolescents, the extent to which these impairments have functional consequences for everyday listening, such as the ability to understand speech in noisy environments, is unknown.Research design: Case-control study.Subjects and methods: Forty youth comprised the participants: 20 had sustained a concussion and were recovering from their injury, and 20 controls had sustained non-concussive orthopaedic (e.g. musculoskeletal) injuries. All were evaluated on the Hearing in Noise Test, an audiologic index of the ability to hear sentences in adverse listening conditions.Results: Children and adolescents recovering from concussions demonstrated an overall impaired ability to perceive speech in noisy backgrounds compared to a peer control group. This deficit also emerged across trials in the most taxing listening condition, and with respect to published, age-normative values.Conclusions: Functional listening skills—such as the ability to understand speech in noise, and the ability to sustain performance over time in taxing auditory conditions—may be compromised in children with concussions. These impairments may exacerbate cognitive and academic challenges associated with concussion injuries, and should be considered in return-to-learn and return-to-play decisions.

Brain potentials to speech perception in noise for patients with schizophrenia

Schizophrenia is characterized with a series of cognitive impairment, including basic information processing such as auditory and speech perception. Especially, patients with schizophrenia experienced additional challenge for speech perception in noisy environment. In this study, brain activity in response to speech sounds was measured in quiet and 6-talker babble conditions from 25 schizophrenia patients and 20 healthy subjects. A double-oddball paradigm was employed, in which /ba/ was played as the standard stimulus with /da/ and /bu/ as the deviant stimuli. Results showed that the schizophrenia group had lower amplitude and longer latency of mismatched negativity (MMN) compared with control group in both the quiet and babble conditions. In addition, there was a significant interaction effect between listening condition and listener group, i.e., the 6-talker babble exerted greater disturbance for schizophrenia. Moreover, the analysis of theta band oscillation in the time window of MMN also supported the above results. These findings indicated that the deficits in the pre-attentive automatic auditory processing in the patients with schizophrenia may underpin their speech perception difficulty in the daily noise environment.Schizophrenia is characterized with a series of cognitive impairment, including basic information processing such as auditory and speech perception. Especially, patients with schizophrenia experienced additional challenge for speech perception in noisy environment. In this study, brain activity in response to speech sounds was measured in quiet and 6-talker babble conditions from 25 schizophrenia patients and 20 healthy subjects. A double-oddball paradigm was employed, in which /ba/ was played as the standard stimulus with /da/ and /bu/ as the deviant stimuli. Results showed that the schizophrenia group had lower amplitude and longer latency of mismatched negativity (MMN) compared with control group in both the quiet and babble conditions. In addition, there was a significant interaction effect between listening condition and listener group, i.e., the 6-talker babble exerted greater disturbance for schizophrenia. Moreover, the analysis of theta band oscillation in the time window of MMN also supported the...

Electrophysiological response during auditory gap detection: Biomarker for sensory and communication alterations in autism spectrum disorder?

ABSTRACTSensory symptoms, including auditory processing deficits, are common in autism spectrum disorder (ASD). Processing of temporal aspects of auditory input is understudied; yet, deficits in this domain could contribute to language-related impairments. In children with ASD and well-matched controls, this study examined electrophysiological response to silent gaps in auditory stimuli. Results revealed attenuated amplitude of the P2 event-related potential (ERP) component in ASD. The P2 amplitude reduction was also associated with sensory, language, and diagnostic features. These results suggest that neural response during auditory gap detection is a promising ASD biomarker that could be useful for stratifying subgroups and evaluating treatment response.

Objective evaluation of binaural summation through acoustic reflex measures

Objective: A previous study [Rawool, V. W. (2016). Auditory processing deficits: Assessment and intervention. New York, NY: Thieme Medical Publishers, Inc., pp. 186–187] demonstrated objective assessment of binaural summation through right contralateral acoustic reflex thresholds (ARTs) in women. The current project examined if previous findings could be generalised to men and to the left ear. Design: Cross-sectional. Study sample: Sixty individuals participated in the study. Left and right contralateral ARTs were obtained in two conditions. In the alternated condition, the probe tone presentation was alternated with the presentation of the reflex activating clicks. In the simultaneous condition, the probe tone and the clicks were presented simultaneously. Binaural summation was calculated by subtracting the ARTs obtained in the simultaneous condition from the ARTs obtained in the alternated condition. Results: MANOVA on ARTs revealed no significant gender or ear effects. The ARTs were significantly lower/better in the simultaneous condition compared to the alternated condition. Conclusions: Binaural summation was 4 dB or higher in 88% of the ears and 6 dB or higher in 76% of ears. Stimulation of six out of the total 120 (0.5%) ears resulted in worse thresholds in the simultaneous condition compared with the alternating condition, suggesting binaural interference.

Evaluation of visual motion perception ability in mice with knockout of the dyslexia candidate susceptibility gene Dcdc2.

Developmental dyslexia is a heritable disability characterized by difficulties in learning to read and write. The neurobiological and genetic mechanisms underlying dyslexia remain poorly understood; however, several dyslexia candidate risk genes have been identified. One of these candidate risk genes-doublecortin domain containing 2 (DCDC2)-has been shown to play a role in neuronal migration and cilia function. At a behavioral level, variants of DCDC2 have been associated with impairments in phonological processing, working memory and reading speed. Additionally, a specific mutation in DCDC2 has been strongly linked to deficits in motion perception-a skill subserving reading abilities. To further explore the relationship between DCDC2 and dyslexia, a genetic knockout (KO) of the rodent homolog of DCDC2 (Dcdc2) was created. Initial studies showed that Dcdc2 KOs display deficits in auditory processing and working memory. The current study was designed to evaluate the association between DCDC2 and motion perception, as these skills have not yet been assessed in the Dcdc2 KO mouse model. We developed a novel motion perception task, utilizing touchscreen technology and operant conditioning. Dcdc2 KOs displayed deficits on the Pairwise Discrimination task specifically as motion was added to visual stimuli. Following behavioral assessment, brains were histologically prepared for neuroanatomical analysis of the lateral geniculate nucleus (LGN). The cumulative distribution showed that Dcdc2 KOs exhibited more small neurons and fewer larger neurons in the LGN. Results compliment findings that DCDC2 genetic alteration results in anomalies in visual motion pathways in a subpopulation of dyslexic patients.

Distinct ERP profiles for auditory processing in infants at-risk for autism and language impairment

Early identification of autism spectrum disorder (ASD) is crucial for the formulation of effective intervention programs. Language deficits may be a hallmark feature of ASD and language delay observed in ASD shows striking similarities to that observed in children with language impairment (LI). Auditory processing deficits are seen in both LI and ASD, however, they have not previously been compared directly using Event-Related Potentials (ERPs) in the two at-risk populations. This study aims to characterize infants at-risk for ASD (HR-ASD) at the electrophysiological level and to compare them with infants at-risk for LI (HR-LI) and controls, to find specific markers with predictive value. At 12-month-old, auditory processing in HR-ASD, HR-LI and controls was characterized via ERP oddball paradigm. All infants were then evaluated at 20 months, to investigate the associations between auditory processing and language/ASD-related outcomes. In both HR-ASD and HR-LI, mismatch response latency was delayed compared to controls, whereas only HR-ASD showed overall larger P3 amplitude compared to controls. Interestingly, these ERP measures correlated with later expressive vocabulary and M-CHAT critical items in the whole sample. These results may support the use of objective measurement of auditory processing to delineate pathophysiological mechanisms in ASD, as compared to LI.

The glucocorticoid antagonist mifepristone attenuates sound-induced long-term deficits in auditory nerve response and central auditory processing in female rats.

Systemic corticosteroids have been the mainstay of treatment for various hearing disorders for more than 30 yr. Accordingly, numerous studies have described glucocorticoids (GCs) and stressors to be protective in the auditory organ against damage associated with a variety of health conditions, including noise exposure. Conversely, stressors are also predictive risk factors for hearing disorders. How both of these contrasting stress actions are linked has remained elusive. Here, we demonstrate that higher corticosterone levels during acoustic trauma in female rats is highly correlated with a decline of auditory fiber responses in high-frequency cochlear regions, and that hearing thresholds and the outer hair cell functions (distortion products of otoacoustic emissions) are left unaffected. Moreover, when GC receptor (GR) or mineralocorticoid receptor (MR) activation was antagonized by mifepristone or spironolactone, respectively, GR, but not MR, inhibition significantly and permanently attenuated trauma-induced effects on auditory fiber responses, including inner hair cell ribbon loss and related reductions of early and late auditory brainstem responses. These findings strongly imply that higher corticosterone stress levels profoundly impair auditory nerve processing, which may influence central auditory acuity. These changes are likely GR mediated as they are prevented by mifepristone.-Singer, W., Kasini, K., Manthey, M., Eckert, P., Armbruster, P., Vogt, M. A., Jaumann, M., Dotta, M., Yamahara, K., Harasztosi, C., Zimmermann, U., Knipper, M., Rüttiger, L. The glucocorticoid antagonist mifepristone attenuates sound-induced long-term deficits in auditory nerve response and central auditory processing in female rats.

Children with autism spectrum disorder have unstable neural responses to sound

Autism spectrum disorder (ASD) is diverse, manifesting in a wide array of phenotypes. However, a consistent theme is reduced communicative and social abilities. Auditory processing deficits have been shown in individuals with ASD-these deficits may play a role in the communication difficulties ASD individuals experience. Specifically, children with ASD have delayed neural timing and poorer tracking of a changing pitch relative to their typically developing peers. Given that accurate processing of sound requires highly coordinated and consistent neural activity, we hypothesized that these auditory processing deficits stem from a failure to respond to sound in a consistent manner. Therefore, we predicted that individuals with ASD have reduced neural stability in response to sound. We recorded the frequency-following response (FFR), an evoked response that mirrors the acoustic features of its stimulus, of high-functioning children with ASD age 7-13years. Evident across multiple speech stimuli, children with ASD have less stable FFRs to speech sounds relative to their typically developing peers. This reduced auditory stability could contribute to the language and communication profiles observed in individuals with ASD.

Effect of auditory temporal processing training on behavioral and electrophysiological functions in central presbycusis

ObjectiveAge-related changes in the central auditory system, particularly auditory temporal processing abilities, were considered among most important factors affecting speech understanding performance in older adults. Once these factors are identified, clinical management procedures could be developed for prevention and treatment. The aim of this study was to determine the effects of short-term auditory training on the behavioral and electrophysiological measurements of auditory function in individuals with age-related temporal processing deficit.Participants and methodsA prospective study of 20 individuals aged 60–67 years with either normal or bilateral symmetric high-frequency hearing loss was conducted. Evaluations of auditory temporal processing using behavioral tests (Pitch Discrimination Test, Pitch Pattern Sequence Test, Auditory Fusion Test-Revised, and Time Compressed Speech Test), P300 potential, and the administration of ‘Amsterdam inventory for auditory disability and handicap’ were performed before and after short-term auditory training.ResultsAll participants demonstrated poor pretraining Pitch Pattern Sequence Test results which were significantly improved after remediation. All patients showed normal pretraining performance on Pitch Discrimination Test, Auditory Fusion Test-Revised, and Time Compressed Speech Test tests. There was a statistically significant increase in P300 amplitude and shortening in latency after remediation.ConclusionShort-term auditory training in older adults with auditory temporal processing deficit led to improvements in temporal sequencing skills and communication in noisy environments. P300 potential has been proved to be an objective indicator of neurophysiologic changes in the central auditory system resulting from auditory experience.RecommendationShort-term auditory training is an efficient rehabilitative tool for elderly people with auditory temporal processing deficit. However, maintenance of treatment effects over time should be evaluated.

Sensory Processing Phenotypes in Fragile X Syndrome.

Fragile X syndrome (FXS) is a neurodevelopmental disorder that causes intellectual disability. It is a leading known genetic cause of autism. In addition to cognitive, social, and communication deficits, humans with FXS demonstrate abnormal sensory processing including sensory hypersensitivity. Sensory hypersensitivity commonly manifests as auditory, tactile, or visual defensiveness or avoidance. Clinical, behavioral, and electrophysiological studies consistently show auditory hypersensitivity, impaired habituation to repeated sounds, and reduced auditory attention in humans with FXS. Children with FXS also exhibit significant visuospatial impairments. Studies in infants and toddlers with FXS have documented impairments in processing texture-defined motion stimuli, temporal flicker, perceiving ordinal numerical sequence, and the ability to maintain the identity of dynamic object information during occlusion. Consistent with the observations in humans with FXS, fragile X mental retardation 1 (Fmr1) gene knockout (KO) rodent models of FXS also show seizures, abnormal visual-evoked responses, auditory hypersensitivity, and abnormal processing at multiple levels of the auditory system, including altered acoustic startle responses. Among other sensory symptoms, individuals with FXS exhibit tactile defensiveness. Fmr1 KO mice also show impaired encoding of tactile stimulation frequency and larger size of receptive fields in the somatosensory cortex. Since sensory deficits are relatively more tractable from circuit mechanisms and developmental perspectives than more complex social behaviors, the focus of this review is on clinical, functional, and structural studies that outline the auditory, visual, and somatosensory processing deficits in FXS. The similarities in sensory phenotypes between humans with FXS and animal models suggest a likely conservation of basic sensory processing circuits across species and may provide a translational platform to not just develop biomarkers but also to understand underlying mechanisms. We argue that preclinical studies in animal models of FXS can facilitate the ongoing search for new therapeutic approaches in FXS by understanding mechanisms of basic sensory processing circuits and behaviors that are conserved across species.

Clinical and Cognitive Significance of Auditory Sensory Processing Deficits in Schizophrenia.

Although patients with schizophrenia exhibit impaired suppression of the P50 event-related brain potential in response to the second of two identical auditory stimuli during a paired-stimulus paradigm, uncertainty remains over whether this deficit in inhibitory gating of auditory sensory processes has relevance for patients' clinical symptoms or cognitive performance. The authors examined associations between P50 suppression deficits and several core features of schizophrenia to address this gap. P50 was recorded from 52 patients with schizophrenia and 41 healthy comparison subjects during a standard auditory paired-stimulus task. Clinical symptoms were assessed with the Scale for the Assessment of Positive Symptoms and the Scale for the Assessment of Negative Symptoms. The MATRICS Consensus Cognitive Battery was utilized to measure cognitive performance in a subsample of 39 patients. Correlation and regression analyses were conducted to examine P50 suppression in relation to clinical symptom and cognitive performance measures. Schizophrenia patients demonstrated a deficit in P50 suppression when compared with healthy subjects, replicating prior research. Within the patient sample, impaired P50 suppression covaried reliably with greater difficulties in attention, poorer working memory, and reduced processing speed. Impaired suppression of auditory stimuli was associated with core pathological features of schizophrenia, increasing confidence that P50 inhibitory processing can inform the development of interventions that target cognitive impairments in this chronic and debilitating mental illness.

Pharmacological modulation of Kv3.1 mitigates auditory midbrain temporal processing deficits following auditory nerve damage

Higher stages of central auditory processing compensate for a loss of cochlear nerve synapses by increasing the gain on remaining afferent inputs, thereby restoring firing rate codes for rudimentary sound features. The benefits of this compensatory plasticity are limited, as the recovery of precise temporal coding is comparatively modest. We reasoned that persistent temporal coding deficits could be ameliorated through modulation of voltage-gated potassium (Kv) channels that regulate temporal firing patterns. Here, we characterize AUT00063, a pharmacological compound that modulates Kv3.1, a high-threshold channel expressed in fast-spiking neurons throughout the central auditory pathway. Patch clamp recordings from auditory brainstem neurons and in silico modeling revealed that application of AUT00063 reduced action potential timing variability and improved temporal coding precision. Systemic injections of AUT00063 in vivo improved auditory synchronization and supported more accurate decoding of temporal sound features in the inferior colliculus and auditory cortex in adult mice with a near-complete loss of auditory nerve afferent synapses in the contralateral ear. These findings suggest modulating Kv3.1 in central neurons could be a promising therapeutic approach to mitigate temporal processing deficits that commonly accompany aging, tinnitus, ototoxic drug exposure or noise damage.

Complementary metrics of human auditory nerve function derived from compound action potentials.

Declines in auditory nerve (AN) function contribute to suprathreshold auditory processing and communication deficits in individuals with normal hearing, hearing loss, hyperacusis, and tinnitus. Procedures to characterize AN loss or dysfunction in humans are limited. We report several novel complementary metrics using the compound action potential (CAP), a direct measure of summated AN activity. Together, these metrics may be used to characterize AN function noninvasively in humans. We examined how these metrics change with stimulus intensity and interpreted these changes within a framework of known physiological properties of the basilar membrane and AN. Our results reveal how neural synchrony and the recruitment of AN fibers with longer first-spike latencies likely contribute to the CAP, affect auditory processing, and differ with noise exposure history in younger adults with normal pure-tone thresholds. Moving forward, this new battery of metrics provides a crucial step toward new diagnostics of AN function in humans. NEW & NOTEWORTHY Loss or inactivity of auditory nerve (AN) fibers is thought to contribute to suprathreshold auditory processing deficits, but evidence-based methods to assess these effects are not available. We describe several novel metrics that together may be used to quantify neural synchrony and characterize AN function in humans.

Magnetoencephalography reveals an increased non-target P3a, but not target P3b, that is associated with high non-clinical psychosocial deficits

Auditory processing deficits are frequently identified in autism and schizophrenia, and the two disorders have been shown to share psychosocial difficulties. This study used magnetoencephalography to investigate auditory processing differences for those with a high degree of a non-clinical autistic and schizotypal trait phenotype, Social Disorganisation (SD). Participants were 18 low (9 female) and 19 high (9 female) SD scorers (18–40 years) who completed a three-stimulus auditory oddball paradigm of speech sounds (standard: 100ms ‘o’, deviant: 150ms ‘o’, novel: 150ms ‘e’). Spatio-temporal cluster analysis revealed increased amplitude for the high SD group in a left (p = 0.006) and a right (p = 0.020) hemisphere cluster in response to the novel non-target. No cluster differences were found in response to the target deviant. These findings suggest that those with a high degree of the SD phenotype recruit more cortical resources when processing unattended, novel speech stimuli, which may lead to psychosocial deficits.

Deficit in Central Auditory Processing as a Biomarker of Pre-Clinical Alzheimer's Disease.

Prevention of dementia due to Alzheimer’s disease (d/AD) requires interventions that slow the disease process prior to symptom onset. To develop such interventions, one needs metrics that assess pre-symptomatic disease progression. Familiar measures of progression include cerebrospinal fluid (CSF) biochemical and imaging analyses, as well as cognitive testing. Changes in the latter can sometimes be difficult to distinguish from effects of “normal” aging. A different approach involves testing of “central auditory processing” (CAP), which enables comprehension of auditory stimuli amidst a distracting background (e.g., conversation in a noisy bar or restaurant). Such comprehension is often impaired in d/AD. Similarly, effortful or diminished auditory comprehension is sometimes reported by cognitively healthy elders, raising the possibility that CAP deficit may be a marker of pre-symptomatic AD. In 187 cognitively and physically healthy members of the aging, AD family history-positive PREVENT-AD cohort, we therefore evaluated whether CAP deficits were associated with known markers of AD neurodegeneration. Such markers included CSF tau concentrations and magnetic resonance imaging volumetric and cortical thickness measures in key AD-related regions. Adjusting for age, sex, education, pure-tone hearing, and APOE ɛ4 status, we observed a persistent relationship between CAP scores and CSF tau levels, entorhinal and hippocampal cortex volumes, cortical thickness, and deficits in cognition (Repeatable Battery for Assessment of Neuropsychological Status total score, and several of its index scales). These cross-sectional observations suggest that CAP may serve as a novel metric for pre-symptomatic AD pathogenesis. They are therefore being followed up longitudinally with larger samples.

Language Experience with a Native-Language Phoneme Sequence Modulates the Effects of Attention on Cortical Sensory Processing.

Auditory evoked potentials (AEP) reflect spectro-temporal feature changes within the spoken word and are sufficiently reliable to probe deficits in auditory processing. The current research assessed whether attentional modulation would alter the morphology of these AEPs and whether native-language experience with phoneme sequences would influence the effects of attention. Native-English and native-Polish adults listened to nonsense word pairs that contained the phoneme sequence onsets /st/, /sət/, /pət/ that occur in both the Polish and English languages and the phoneme sequence onset /pt/ that occurs in the Polish language, but not the English language. Participants listened to word pairs within two experimental conditions designed to modulate attention. In one condition, participants listened to word pairs and performed a behavioral task to the second word in the pairs (“with task”) and in the alternate condition participants listened to word pairs without performing a task (“without task”). Conditions were counterbalanced so that half the English and Polish subjects performed the “without task” condition as the first testing session and the “with task” condition as the second testing session. The remaining English and Polish subjects performed the tasks in the reverse order. Two or more months separated the testing sessions. Task conditions did not modulate the morphology of the AEP. Attention, however, modulated the AEP by producing a negative shift in the overall waveform. This effect of attention was modulated by experience with a native-language phoneme sequence. Thus, only Polish listeners showed an effect of attention to the native language /pt/ onset when the behavioral task occurred as the second testing session for which attention demands were reduced. This effect began at 400 ms and suggests a mechanism at intermediate stages within auditory cortex that facilitates recognition of the native language for comprehension.

Electrophysiological determination of backward masking function

Backward Masking (BM) functions have been shown to relate to age, lead toxicity, and in children with language disorders. These functions may be indicative of auditory processing deficits. This study investigated if Evoked Potentials (EP) could be utilized to obtain BM functions. The design of this study allowed observation of the early, middle, and late auditory evoked potentials. This process allowed us to observe the differential electrophysiological responses of evoked potentials during the BM effect. This study was randomized using four different stimulus conditions. With a long inter-stimulus interval and high sample rate simultaneous early, middle, and late potentials were obtained. The stimuli were a pure-tone alone, (1) 1000 Hz, (2) a masking noise alone, (3) the pure-tone followed by the masking noise, and (4) a control condition with no auditory stimulus. This approach, using a randomization allowed any adaptation or habituation to the stimuli to be equally distributed within each condition. Using arithmetic operations on the derived evoked potentials allows for localization of brain structures utilized in BM processing. Results indicated the determination of BM functions can be obtained objectively.

Do prereaders’ auditory processing and speech perception predict later literacy?

Developmental dyslexia has frequently been linked to deficits in auditory processing and speech perception. However, the presence and precise nature of these deficits and the direction of their relation with reading, remains debated. In this longitudinal study, 87 five-year-olds at high and low family risk for dyslexia were followed before and during different stages of reading acquisition. The processing of different auditory cues was investigated, together with performance on speech perception and phonology and reading. Results show no effect of family risk for dyslexia on prereading auditory processing and speech perception skills. However, a relation is present between the performance on these skills in kindergarten and later phonology and literacy. In particular, links are found with the auditory processing of cues characteristic for the temporal speech amplitude envelope, rather than with other auditory cues important for speech intelligibility. Hereby, cues embedded in the speech amplitude envelope show to be related to a broad range of phonological precursors for reading. In addition, speech-in-noise perception demonstrates to operate as the most contributing factor for later phonological awareness and to be a predictor for reading mediated by the association with phonology. This study provides behavioral support for the link between prereading speech amplitude envelope processing and speech perception for future phonology and reading.