Central auditory processing and perception of sound

Η αντίληψη ύπαρξης ήχου σε απουσία εξωτερικής ηχητικής πηγής, αν και δεν είναι πλήρως κατανοητή ως προς την παθοφυσιολογία της, συνδέεται με βλάβες, είτε στο περιφερικό, είτε στο κεντρικό ακουστικό νευρικό σύστημα. Η λειτουργία του κεντρικού ακουστικού νευρικού συστήματος επιτρέπει την επεξεργασία της ακουστικής πληροφορίας, η οποία μεταφέρεται σε πραγματικό χρόνο, τόσο από την περιφέρεια του ακουστικού συστήματος προς το κέντρο της ακοής στον εγκεφαλικό φλοιό, όσο και από τον εγκεφαλικό φλοιό προς τα υποφλοιικά κέντρα της ακοής. Παραδείγματα που έχουν ερευνηθεί είναι οι ακουστικές ψευδαισθήσεις και οι εμβοές. Τα ελλείμματα ακουστικής επεξεργασίας, καθώς και η παθολογία του κεντρικού ακουστικού νευρικού συστήματος μπορούν μερικώς να εξηγήσουν την κλινική εικόνα ασθενών που αντιλαμβάνονται ήχο, όταν αυτός δεν υπάρχει. Με βάση σύγχρονα δημοσιευμένα ερευνητικά δεδομένα η βέλτιστη κλινική προσέγγιση, είτε ψυχιατρικών ασθενών με ακουστικές ψευδαισθήσεις, είτε ασθενών με εμβοές μπορεί να περιλαμβάνει εκτίμηση ακουστικής επεξεργασίας. Η εξέταση ακουστικής επεξεργασίας, μπορεί πρωτίστως να περιλαμβάνει χρονική ανάλυση, ομιλητική ακουομετρία σε θόρυβο και διάκριση συχνοτήτων και με τον τρόπο αυτό να εκτιμά καλύτερα τα καθημερινά προβλήματα του ασθενούς αναφορικά με την ακουστική αντίληψη και την επικοινωνία του.Perception of sound without the presence of an external source, although not fully understood pathophysiologically, is known to be linked to lesions in either the peripheral or the central auditory nervous system. Functionality of the central auditory nervous system permits the processing of auditory information which is mediated in real time both as a bottom-up (from the peripheral auditory nervous system to auditory cortex) and a top-down (from the auditory cortex to subcortical structures) process. Examples of symptoms researched are auditory hallucinations and tinnitus. Auditory processing deficits, as well as, central auditory nervous pathology may partly explain patients perceiving sound in the absence of an external source. Based on current published research, an optimal clinical assessment of either psychiatric patients with auditory hallucinations or patients with tinnitus, may include central auditory processing evaluation. This evaluation may primarily include temporal processing, speech in babble and frequency discrimination abilities of the patient to better assess everyday difficulties in listening and communication

Deficits in Auditory Rhythm Perception in Children With Auditory Processing Disorder Are Unrelated to Attention

Auditory processing disorder (APD) is defined as a specific deficit in the processing of auditory information along the central auditory nervous system, including bottom-up and top-down neural connectivity. Even though music comprises a big part of audition, testing music perception in APD population has not yet gained wide attention in research. This work tests the hypothesis that deficits in rhythm perception occur in a group of subjects with APD. The primary focus of this study is to measure perception of a simple auditory rhythm, i.e., short isochronous sequences of beats, in APD children and to compare their performance to age-matched normal controls. The secondary question is to study the relationship between cognition and auditory processing of rhythm perception. We tested 39 APD children and 25 control children aged between 6 and 12 years via (a) clinical APD tests, including a monaural speech in noise test, (b) isochrony task, a test measuring the detection of small deviations from perfect isochrony in a isochronous beats sequence, and (c) two cognitive tests (auditory memory and auditory attention). APD children scored worse in isochrony task compared to the age-matched control group. In the APD group, neither measure of cognition (attention nor memory) correlated with performance in isochrony task. Left (but not right) speech in noise performance correlated with performance in isochrony task. In the control group a large correlation (r = −0.701, p = 0.001) was observed between isochrony task and attention, but not with memory. The results demonstrate a deficit in the perception of regularly timed sequences in APD that is relevant to the perception of speech in noise, a ubiquitous complaint in this condition. Our results suggest (a) the existence of a non-attention related rhythm perception deficit in APD children and (b) differential effects of attention on task performance in normal vs. APD children. The potential beneficial use of music/rhythm training for rehabilitation purposes in APD children would need to be explored

The Use of the Gaps-In-Noise Test as an Index of the Enhanced Left Temporal Cortical Thinning Associated with the Transition between Mild Cognitive Impairment and Alzheimer's Disease

Background: The known link between auditory perception and cognition is often overlooked when testing for cognition. Purpose: To evaluate auditory perception in a group of older adults diagnosed with mild cognitive impairment (MCI). Research Design: A cross-sectional study of auditory perception. Study Sample: Adults with MCI and adults with no documented cognitive issues and matched hearing sensitivity and age. Data collection: Auditory perception was evaluated in both groups, assessing for hearing sensitivity, speech in babble (SinB), and temporal resolution. Results: Mann‐Whitney test revealed significantly poorer scores for SinB and temporal resolution abilities of MCIs versus normal controls for both ears. The right-ear gap detection thresholds on the Gaps-In-Noise (GIN) Test clearly differentiated between the two groups (p < 0.001), with no overlap of values. The left ear results also differentiated the two groups (p < 0.01); however, there was a small degree of overlap ∼8-msec threshold values. With the exception of the left-ear inattentiveness index, which showed a similar distribution between groups, both impulsivity and inattentiveness indexes were higher for the MCIs compared to the control group. Conclusions: The results support central auditory processing evaluation in the elderly population as a promising tool to achieve earlier diagnosis of dementia, while identifying central auditory processing deficits that can contribute to communication deficits in the MCI patient population. A measure of temporal resolution (GIN) may offer an early, albeit indirect, measure reflecting left temporal cortical thinning associated with the transition between MCI and Alzheimer’s disease

Reliability and cultural applicability of the Greek version of the International Personality Disorders Examination.

BACKGROUND: The International Personality Disorders Examination (IPDE) constitutes the proposal of the WHO for the reliable diagnosis of personality disorders (PD). The IPDE assesses pathological personality and is compatible both with DSM-IV and ICD-10 diagnosis. However it is important to test the reliability and cultural applicability of different IPDE translations. METHODS: Thirty-one patients (12 male and 19 female) aged 35.25 ± 11.08 years, took part in the study. Three examiners applied the interview (23 interviews of two and 8 interviews of 3 examiners, that is 47 pairs of interviews and 70 single interviews). The phi coefficient was used to test categorical diagnosis agreement and the Pearson Product Moment correlation coefficient to test agreement concerning the number of criteria met. RESULTS: Translation and back-translation did not reveal specific problems. Results suggested that reliability of the Greek translation is good. However, socio-cultural factors (family coherence, work environment etc) could affect the application of some of the IPDE items in Greece. The diagnosis of any PD was highly reliable with phi >0.92. However, diagnosis of non-specfic PD was not reliable at all (phi close to 0) suggesting that this is a true residual category. Dianosis of specific PDs were highly reliable with the exception of schizoid PD. Diagnosis of antisocial and Borderline PDs were perfectly reliable with phi equal to 1.00. CONCLUSIONS: The Greek translation of the IPDE is a reliable instrument for the assessment of personality disorder but cultural variation may limit its applicability in international comparisons

Absence of Rhythm Benefit on Speech in Noise Recognition in Children Diagnosed With Auditory Processing Disorder

Auditory processing disorder (APD) is a specific deficit in the processing of auditory information along the central auditory nervous system. It is characterized mainly by deficits in speech in noise recognition. APD children may also present with deficits in processing of auditory rhythm. Rhythmic neural entrainment is commonly present in perception of both speech and music, while auditory rhythmic priming of speech in noise has been known to enhance recognition in typical children. Here, we test the hypothesis that the effect of rhythmic priming is compromised in APD children, and further assessed for correlations with verbal and non-verbal auditory processing and cognition. Forty APD children and 33 neurotypical ones were assessed through (a) WRRC, a test measuring the effects of rhythmic priming on speech in noise recognition, (b) a battery of auditory processing tests, commonly used in APD diagnosis, and (c) two cognitive tests, assessing working memory and auditory attention respectively. Findings revealed that (a) the effect of rhythmic priming on speech in noise recognition is absent in APD children, (b) it is linked to non-verbal auditory processing, and (c) it is only weakly dependent on cognition. We discuss these findings in light of Dynamic Attention Theory, neural entrainment and neural oscillations and suggest that these functions may be compromised in APD children. Further research is needed (a) to explore the nature of the mechanics of rhythmic priming on speech in noise perception and why the effect is absent in APD children, (b) which other mechanisms related to both rhythm and language are also affected in this population, and (c) whether music/rhythm training can restore deficits in rhythm effects

Prevalence and correlates of neurological soft signs in healthy controls without family history of any mental disorder: A neurodevelopmental variation rather than a specific risk factor?

OBJECTIVE: Neurological soft signs (NSS) are a group of minor non-localizable neurological abnormalities found more often in patients with schizophrenia and other mental disorders. The aim of the current study was to investigate their prevalence and correlates in healthy controls without family history of any mental disorder. MATERIAL AND METHODS: The study sample included 122 normal subjects (66 males and 56 females; aged 32.89+/-9.91years old). The assessment included the Neurological Evaluation Scale (NES), and a number of scales assessing the subthreshold symptoms (MADRS, STAI) and functioning (GAF). Data on a number of socio-demographic variables were also gathered. The statistical analysis included the development of basic statistics tables and the calculation of Pearson correlation coefficients. RESULTS: The results of the current study suggest that more than half of the study sample manifested at least one NSS and approximately 5% more than four. Still, the reported prevalence and NES scores are lower form those reported in the literature probably because of the carefully selected study sample. There were no significant correlations between NSS and any socio-demographic or clinical variable. DISCUSSION: The current study is the first to study NSS in subjects without family history of any mental disorder and reports the presence of frequent silent neurodevelopmental events in the general population, probably in the form of a neurodevelopmental variation and possibly a weak generic rather than specific risk factor

Neurological soft signs significantly differentiate schizophrenia patients from healthy controls

OBJECTIVE: Neurological soft signs (NSS) are a group of minor non-localisable neurological abnormalities found more often in patients with schizophrenia. The aim of the current study was to test for the effect of gender, age, parental age, age at onset and clinical symptomatology on NSS. Material and methods The study sample included 133 patients suffering from schizophrenia according to DSM-IV-TR (77 males and 56 females; aged 33.55+/-11.22 years old) and 122 normal controls (66 males and 56 females; aged 32.89+/-9.91 years old). The assessment included the Neurological Evaluation Scale (NES), and a number of scales assessing the clinical symptoms and adverse effects especially extrapyramidal. The statistical analysis included exploratory t-test, simple linear regression analysis, analysis of covariance and the calculation of correlation coefficients. RESULTS: The results of the current study confirm that NSS are more frequent in patients with schizophrenia in comparison with normal controls (Wilks=0.622, p<0.0001), but do not support an effect of gender, age, age at onset, paternal or maternal age, education, medication status or clinical subtype of schizophrenia on NES scores. Discussion Overall these results suggest that NSS constitute an independent (from the rest of symptoms), core (present in the vast majority of patients) and trait (unrelated to age and probably to the stage of schizophrenia) symptom of schizophrenia which could be of value in the clinical assessment and research of schizophrenia. Overall these results are not in full accord with the literature, but they could serve to fill in gaps and inconsistencies observed so far

Spoken word recognition enhancement due to preceding synchronized beats compared to unsynchronized or unrhythmic beats

The relation between rhythm and language has been investigated over the last decades, with evidence that these share overlapping perceptual mechanisms emerging from several different strands of research. The dynamic Attention Theory posits that neural entrainment to musical rhythm results in synchronized oscillations in attention, enhancing perception of other events occurring at the same rate. In this study, this prediction was tested in 10 year-old children by means of a psychoacoustic speech recognition in babble paradigm. It was hypothesized that rhythm effects evoked via a short isochronous sequence of beats would provide optimal word recognition in babble when beats and word are in sync. We compared speech recognition in babble performance in the presence of isochronous and in sync vs. non-isochronous or out of sync sequence of beats. Results showed that (a) word recognition was the best when rhythm and word were in sync, and (b) the effect was not uniform across syllables and gender of subjects. Our results suggest that pure tone beats affect speech recognition at early levels of sensory or phonemic processing

Neurological soft signs significantly differentiate schizophrenia patients from healthy controls.

OBJECTIVE: Neurological soft signs (NSS) are a group of minor non-localisable neurological abnormalities found more often in patients with schizophrenia. The aim of the current study was to test for the effect of gender, age, parental age, age at onset and clinical symptomatology on NSS.Material and methodsThe study sample included 133 patients suffering from schizophrenia according to DSM-IV-TR (77 males and 56 females; aged 33.55±11.22 years old) and 122 normal controls (66 males and 56 females; aged 32.89±9.91 years old). The assessment included the Neurological Evaluation Scale (NES), and a number of scales assessing the clinical symptoms and adverse effects especially extrapyramidal. The statistical analysis included exploratory t-test, simple linear regression analysis, analysis of covariance and the calculation of correlation coefficients. RESULTS: The results of the current study confirm that NSS are more frequent in patients with schizophrenia in comparison with normal controls (Wilks=0.622, p<0.0001), but do not support an effect of gender, age, age at onset, paternal or maternal age, education, medication status or clinical subtype of schizophrenia on NES scores.DiscussionOverall these results suggest that NSS constitute an independent (from the rest of symptoms), core (present in the vast majority of patients) and trait (unrelated to age and probably to the stage of schizophrenia) symptom of schizophrenia which could be of value in the clinical assessment and research of schizophrenia. Overall these results are not in full accord with the literature, but they could serve to fill in gaps and inconsistencies observed so far