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

Propriedades químicas de uma Terra Roxa Estruturada influenciadas pela cobertura vegetal de inverno e pela adubação orgânica e mineral

O presente trabalho teve por objetivo avaliar a influência da cobertura vegetal de inverno, constituída de uma associação de aveia preta (Avena strigosa Schreb) com nabo forrageiro (Raphanus sativus L.), da adubação orgânica com esterco de aves e da adubação mineral sobre propriedades químicas de uma Terra Roxa Estruturada do estado de Santa Catarina. As análises foram realizadas em amostras de solo coletadas em agosto de 1994 e janeiro de 1995, nas profundidades de 0-10, 10-20 e 20-30 cm, em um experimento iniciado em 1990. Observou-se que a cobertura vegetal de inverno mostrou-se eficiente na manutenção de nutrientes, especialmente o potássio, e dos níveis de carbono orgânico, dentro dos limites da camada arável. O uso de adubo orgânico proporcionou acúmulo de nutrientes no solo, enquanto os adubos organomineral e mineral mostraram tendência de redução, principalmente dos níveis de potássio do solo