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1.
Can J Psychiatry ; 66(12): 1085-1093, 2021 12.
Article in English | MEDLINE | ID: mdl-33353429

ABSTRACT

OBJECTIVE: Assessing global functioning in psychiatric emergency settings is important for clinicians to estimate severity of mental disorders, devise a treatment plan, and assess the evolution of their patients' progression over time. The World Health Organization Disability Assessment Schedule-2.0 (WHODAS-2) measures psychological, social, and professional functioning and is recommended as a standardized instrument of choice for use in psychiatric settings. Yet, studies investigating disability profiles of mental disorders using the WHODAS-2 are scarce, and psychometric properties have not been evaluated in a psychiatric emergency context. We describe and compare WHODAS-2 (12-item version) scores across mental disorders (anxiety, mood, psychotic, personality, and substance abuse) in adults admitted to psychiatric emergency. METHODS: Data from the Signature Bank were used. Participants admitted to psychiatric emergency completed the WHODAS-2 at admission (n = 1,125). Mental disorders were evaluated by psychiatrists, and WHODAS-2 scores were compared across groups. Psychometric properties were evaluated using confirmatory factor analysis (CFA). RESULTS: Higher mean WHODAS-2 scores were reported by those with anxiety, mood, and personality disorders (P < 0.001) compared to other psychopathologies. The measure showed good internal consistency (global score α = 0.88; domain subscores α = 0.59 to 0.85) and acceptable goodness of fit indices in CFA confirming the original structure of WHODAS-2. CONCLUSIONS: Findings from this large-scale study could assist clinicians in interpreting WHODAS-2 scores in psychiatric populations and provide a more detailed portrait of disability profiles associated with different clinical diagnoses.


Subject(s)
Disability Evaluation , Mental Disorders , Adult , Humans , Mental Disorders/diagnosis , Mental Disorders/epidemiology , Psychometrics , Reproducibility of Results , World Health Organization
2.
Mon Not R Astron Soc ; 478(1): 906-925, 2018 Jul.
Article in English | MEDLINE | ID: mdl-30573924

ABSTRACT

We test if the cosmological zoom-in simulations of isolated galaxies from the FIRE project reproduce the properties of ultra diffuse galaxies (UDGs). We show that outflows that dynamically heat galactic stars, together with a passively aging stellar population after imposed quenching, naturally reproduce the observed population of red UDGs, without the need for high spin haloes, or dynamical influence from their host cluster. We reproduce the range of surface brightness, radius, and absolute magnitude of the observed red UDGs by quenching simulated galaxies at a range of different times. They represent a mostly uniform population of dark matter-dominated dwarf galaxies with M * ~ 108 M☉, low metallicity, and a broad range of ages; the more massive the UDGs, the older they are. The most massive red UDG in our sample(M * ~ 3 × 108 M☉) requires quenching at z ~ 3 when its halo reached M h ~ 1011M☉. Our simulated UDGs form with normal stellar-to-halo ratios and match the central enclosed masses and the velocity dispersions of the observed UDGs. Enclosed masses remain largely fixed across a broad range of quenching times because the central regions of their dark matter haloes complete their growth early. If our simulated dwarfs are not quenched, they evolve into bluer low surface brightness galaxies with M/L similar to observed field dwarfs. While our simulation sample covers a limited range of formation histories and halo masses, we predict that UDG is a common, and perhaps even dominant, galaxy type around M * ~ 108 M☉, both in the field and in clusters.

3.
Geophys Res Lett ; 45(8): 3445-3452, 2018 Apr 28.
Article in English | MEDLINE | ID: mdl-30034048

ABSTRACT

We have monitored a newly erupted volcanic island in the Kingdom of Tonga, unofficially known as Hunga Tonga Hunga Ha'apai, by means of relatively frequent high spatial resolution (~50 cm) satellite observations. The new ~1.8 km2 island formed as a tuff cone over the course of a month-long hydromagmatic eruption in early 2015 in the Tonga-Kermadec volcanic arc. Such ash-dominated eruptions usually produce fragile subaerial landscapes that wash away rapidly due to marine erosion, as occurred nearby in 2009. Our measured rates of erosion are ~0.00256 km3/year from derived digital topographic models. Preliminary measurements of the topographic expression of the primary tuff cone over ~30 months suggest a lifetime of ~19 years (and potentially up to 42 years). The ability to measure details of a young island's landscape evolution using satellite remote sensing has not previously been possible at these spatial and temporal resolutions.

4.
Stress ; 20(1): 95-111, 2017 01.
Article in English | MEDLINE | ID: mdl-28124571

ABSTRACT

In 2008, the National Institute of Mental Health (NIMH) announced that in the next few decades, it will be essential to study the various biological, psychological and social "signatures" of mental disorders. Along with this new "signature" approach to mental health disorders, modifications of DSM were introduced. One major modification consisted of incorporating a dimensional approach to mental disorders, which involved analyzing, using a transnosological approach, various factors that are commonly observed across different types of mental disorders. Although this new methodology led to interesting discussions of the DSM5 working groups, it has not been incorporated in the last version of the DSM5. Consequently, the NIMH launched the "Research Domain Criteria" (RDoC) framework in order to provide new ways of classifying mental illnesses based on dimensions of observable behavioral and neurobiological measures. The NIMH emphasizes that it is important to consider the benefits of dimensional measures from the perspective of psychopathology and environmental influences, and it is also important to build these dimensions on neurobiological data. The goal of this paper is to present the perspectives of DSM5 and RDoC to the science of mental health disorders and the impact of this debate on the future of human stress research. The second goal is to present the "Signature Bank" developed by the Institut Universitaire en Santé Mentale de Montréal (IUSMM) that has been developed in line with a dimensional and transnosological approach to mental illness.


Subject(s)
Mental Health , National Institute of Mental Health (U.S.) , Stress, Psychological , Environment , Humans , Psychopathology , Research , United States
5.
Int J Pediatr Otorhinolaryngol ; 78(1): 39-45, 2014 Jan.
Article in English | MEDLINE | ID: mdl-24295851

ABSTRACT

INTRODUCTION: Solid cervical lateral neck masses in children may require surgical biopsy to confirm appropriate diagnostic and begin a directed therapeutic treatment. We aimed to describe the contribution of pathological results and compare them with the clinical diagnosis and the paraclinical tools. METHODS: A retrospective review of surgical biopsies for solid lateral neck masses in children over a ten year period in a pediatric tertiary center was conducted. Demographic, imaging, laboratory analysis, surgical and pathological data were collected and analyzed using descriptive statistics with SPSS 17.0. RESULTS: 44 biopsies were done between 2002 and 2012. Inflammatory masses were found in 26/44 biopsies with half of them (13/26) being nontuberculous mycobacterial (NTM) lymphadenitis. Non-inflammatory/benign masses represented 9/44 biopsies and 5/44 masses were of malignant etiology. Malignant masses imaging had a sensitivity and specificity of 33% and 75%, respectively, for ultrasound, whereas Neck CT scan had 33% and 77%, respectively. The contribution of pathological results to the clinical management was questionable in 39% (17/44) of biopsies. CONCLUSION: Inflammatory masses with NTM lymphadenitis were the most common diagnosis. Imaging was not helpful in establishing the diagnosis. Heterogeneity in the management of solid lateral neck masses between clinicians was important and indicates the need for guideline approach.


Subject(s)
Lymphadenitis/pathology , Lymphoproliferative Disorders/pathology , Mycobacterium Infections, Nontuberculous/pathology , Neck/pathology , Pilomatrixoma/pathology , Skin Neoplasms/pathology , Adolescent , Biopsy , Child , Child, Preschool , Diagnosis, Differential , Female , Humans , Infant , Lymph Node Excision , Lymphadenitis/surgery , Lymphoproliferative Disorders/surgery , Male , Mycobacterium Infections, Nontuberculous/surgery , Pilomatrixoma/surgery , Retrospective Studies , Sensitivity and Specificity , Skin Neoplasms/surgery , Tomography, X-Ray Computed , Ultrasonography
6.
Noise Health ; 6(21): 17-37, 2003.
Article in English | MEDLINE | ID: mdl-14965451

ABSTRACT

Many jobs at the Department of Fisheries and Oceans Canada (DFO) have several features in common: they are often performed in noisy environments and involve a number of auditory skills and abilities, such as speech communication, sound localization, and sound detection. If an individual lacks these skills and abilities, it may constitute a safety risk for this individual, as well as for fellow workers and the general public. A number of scientific models have been developed to predict performance on these auditory skills based on diagnostic measures of hearing such as pure-tone audiograms. While these models have significant scientific and research value, they are unable to provide accurate predictions of real life performance on auditory skills necessary to perform hearing-critical jobs. An alternative and more accurate approach has been developed in this research project. A direct measure of functional speech perception in noise (Hearing in Noise Test: HINT) has been identified and validated for use in screening applicants for hearing-critical jobs in DFO. This screening tool has adequate and well-defined psychometric properties (e.g. reliability, sensitivity, and validity) so that screening test results can be used to predict an individual's ability to perform critical auditory skills in noisy environments, with a known degree of prediction error. Important issues must be considered when setting screening criteria. First, the concept of hearing-critical tasks must be reviewed, since these tasks are often performed in high noise levels where normally-hearing people cannot hear adequately. Second, noise-induced hearing loss is frequent in these noisy environments, and workers who acquire a hearing loss might not continue to meet the minimal auditory screening criteria throughout their career. Other senses (e.g., vision, touch) also play an important role in these environments. Third, adaptation strategies have to be considered when recruits or incumbents fail the screening test.


Subject(s)
Hearing Loss/diagnosis , Noise, Occupational/adverse effects , Speech Perception/classification , Adult , Canada , Fisheries , Hearing Loss/etiology , Humans , Psychometrics , Reference Values , Reproducibility of Results , Sensitivity and Specificity , Task Performance and Analysis
7.
J Med Genet ; 39(7): 473-7, 2002 Jul.
Article in English | MEDLINE | ID: mdl-12114476

ABSTRACT

Clinical otosclerosis (OMIM 166800/605727) has a prevalence of 0.2-1% among white adults, making it the single most common cause of hearing impairment in this group. It is caused by abnormal bone homeostasis of the otic capsule with the consequent development of sclerotic foci that invade the stapedio-vestibular joint (oval window) interfering with free motion of the stapes. Impaired ossicular chain mobility results in a conductive hearing loss. We identified the first locus for otosclerosis (OTSC1) on chromosome 15 in 1998 and reported a second locus (OTSC2) on chromosome 7 last year. Here we present results of a genome wide linkage study on a large Cypriot family segregating otosclerosis. Results of this study exclude linkage to OTSC1 and OTSC2 and identify a third locus, OTSC3, on chromosome 6p. The defined OTSC3 interval covers the HLA region, consistent with reported associations between HLA-A/HLA-B antigens and otosclerosis.


Subject(s)
Chromosomes, Human, Pair 6/genetics , Genetic Linkage/genetics , Genetic Markers/genetics , Otosclerosis/genetics , Chromosome Mapping/methods , Female , Genetic Testing , Humans , Lod Score , Male , Pedigree
8.
J Otolaryngol ; 29(5): 290-8, 2000 Oct.
Article in English | MEDLINE | ID: mdl-11108488

ABSTRACT

OBJECTIVE: The aim of this study was to evaluate ultrasound (US) and a new videobronchoscopic (VB) technique in the measurement of the subglottic lumen diameter. DESIGN: This blind prospective animal study of 62 recently sacrificed rabbits was conducted at the Montreal Children's Hospital. METHODS: Three different diameter measurements of the subglottis were assessed using B-mode US on each intact animal. The same diameter measurements, as well as a fourth, were estimated with a VB measuring technique. Finally, the subglottic area was surgically exposed allowing for direct caliper measurements of all four corresponding diameters. All three US measurements on each of the 62 rabbits and all four VB measurements on each of the 60 rabbits were compared with the gold standard corresponding caliper measurements. RESULTS: Statistical analysis revealed strikingly convergent values in subglottic lumen diameter measurements using US and calipers. The mean difference between these methods for all 186 observations was 0.11 mm. With 95% confidence, the maximum discordance was less than 0.30 mm on the smallest evaluated lumen. Convergent values were also demonstrated in subglottic lumen diameter measurements using VB and calipers. The mean difference between these methods for all 240 observations was 0.16 mm. With 95% confidence, the maximum discordance was less than 0.37 mm on the smallest evaluated lumen. Pearson's correlation coefficient supported a strong and positive relationship between US and caliper measurements as well as VB and caliper measurements. Simple linear regression model indicated that the subglottic lumen diameter could be predicted by both US and our VB technique. CONCLUSION: This work represents the first attempt to validate B-mode US and a VB technique as measuring tools for the subglottic lumen diameter. Our results have clearly shown that both methods are precise measuring modalities for this purpose. With further studies, these two objective methods of measuring the subglottic diameter could be adopted universally. The precise knowledge of this diameter could help physicians recognize and describe the severity of a narrowed lumen. Reporting results in such a standardized fashion, by either US or VB, could facilitate communication among clinicians and institutions.


Subject(s)
Bronchoscopy/methods , Glottis/anatomy & histology , Glottis/diagnostic imaging , Video Recording , Animals , Linear Models , Prospective Studies , Rabbits , Ultrasonography
9.
Otolaryngol Head Neck Surg ; 123(5): 533-8, 2000 Nov.
Article in English | MEDLINE | ID: mdl-11077335

ABSTRACT

BACKGROUND: Molecular biologic evidence to support an etiologic role for allergy in the pathogenesis of persistent otitis media with effusion (OME) is lacking. OBJECTIVE: The goal of this article was to document expression of allergy-associated Th-2-type cytokines and inflammatory cells in the middle ear mucosa of children with persistent OME. METHODS: With immunocytochemistry (CD3, major basic protein) and in situ hybridization (interleukin-5 mRNA), middle ear biopsy specimens from 7 children with persistent OME were stained. Nonatopic stapedectomy patients with no history of otitis media served as controls (n = 7). RESULTS: There was a statistically significant (P< 0.05) difference in expression of CD3, major basic protein, and interleukin-5 between experimental and control subjects. All 8 OME patients proved to be atopic by ELISA testing. CONCLUSIONS: Type I allergy involving a Th-2-type cytokine and cellular profile may be a contributing factor in the persistence of OME in atopic children. SIGNIFICANCE: The middle ear may serve as a target organ for allergic inflammation, suggesting that appropriate allergy management may be a useful adjunct to the management of OME.


Subject(s)
Blood Proteins/metabolism , Ear, Middle/metabolism , Inflammation Mediators/metabolism , Interleukin-5/metabolism , Otitis Media with Effusion/immunology , Otitis Media with Effusion/metabolism , Ribonucleases , Biopsy , CD3 Complex/metabolism , Child , Child, Preschool , Chronic Disease , Ear, Middle/pathology , Enzyme-Linked Immunosorbent Assay , Eosinophil Granule Proteins , Humans , Immunohistochemistry , In Situ Hybridization
10.
J Acoust Soc Am ; 108(2): 743-52, 2000 Aug.
Article in English | MEDLINE | ID: mdl-10955641

ABSTRACT

An experiment was conducted to determine the effect of aging on sound localization. Seven groups of 16 subjects, aged 10-81 years, were tested. Sound localization was assessed using six different arrays of four or eight loudspeakers that surrounded the subject in the horizontal plane, at a distance of 1 m. For two 4-speaker arrays, one loudspeaker was positioned in each spatial quadrant, on either side of the midline or the interaural axis, respectively. For four 8-speaker arrays, two loudspeakers were positioned in each quadrant, one close to the midline and the second separated from the first by 15 degrees, 30 degrees, 45 degrees, or 60 degrees. Three different 300-ms stimuli were localized: two one-third-octave noise bands, centered at 0.5 and 4 kHz, and broadband noise. The stimulus level (75 dB SPL) was well above hearing threshold for all subjects tested. Over the age range studied, percent-correct sound-source identification judgments decreased by 12%-15%. Performance decrements were apparent as early as the third decade of life. Broadband noise was easiest to localize (both binaural and spectral cues were available), and the 0.5-kHz noise band, the most difficult to localize (primarily interaural temporal difference cue available). Accuracy was relatively higher in front of than behind the head, and errors were largely front/back mirror image reversals. A left-sided superiority was evident until the fifth decade of life. The results support the conclusions that the processing of spectral information becomes progressively less efficient with aging, and is generally worse for sources on the right side of space.


Subject(s)
Aging/physiology , Sound Localization/physiology , Adolescent , Adult , Aged , Aged, 80 and over , Auditory Threshold/physiology , Child , Female , Hearing/physiology , Humans , Male , Middle Aged
11.
J Am Acad Audiol ; 9(5): 315-31, 1998 Oct.
Article in English | MEDLINE | ID: mdl-9806406

ABSTRACT

Auditory steady-state responses to amplitude-modulated tones with modulation frequencies between 80 and 105 Hz can be recorded when multiple stimuli are presented simultaneously through a soundfield speaker and amplified using a hearing aid. Responses were recorded at carrier frequencies of 500, 1000, 2000, and 4000 Hz in a group of 35 hearing-impaired children using hearing aids. The physiologic responses were recorded at intensities close to the behavioral thresholds for sounds in the aided condition, with average differences between the physiologic and behavioral thresholds of 17, 13, 13, and 16 dB for carrier frequencies 500, 1000, 2000, and 4000 Hz. The technique shows great promise as a way to assess aided thresholds objectively in subjects who cannot reliably respond on behavioral testing.


Subject(s)
Auditory Threshold , Deafness/therapy , Hearing Aids , Audiometry, Pure-Tone , Child , Child, Preschool , Evoked Potentials, Auditory, Brain Stem , Female , Humans , Male , Severity of Illness Index
12.
J Radiol ; 79(5): 437-40, 1998 May.
Article in French | MEDLINE | ID: mdl-9757274

ABSTRACT

Ameloblastic carcinoma is an exceptionally rare odontogenic tumor. Ameloblastoma is considered malignant if there is evidence of metastasis or histological features of malignancy. Present classification of these tumors is debated. Several authors use the term malignant ameloblastoma for tumours that metastasize despite "benign" histological features whereas ameloblastic carcinoma is referred to as a tumor with malignant histological features regardless of its metastatic potential. We report a case of mandibular ameloblastic carcinoma with cervical lymph node metastasis in a 70-year-old man, documented by MRI and CT. We discuss current knowledge on these tumors.


Subject(s)
Mandibular Neoplasms/diagnosis , Odontogenic Tumors/diagnosis , Adenocarcinoma/surgery , Aged , Humans , Lymphatic Metastasis/diagnosis , Lymphatic Metastasis/diagnostic imaging , Lymphatic Metastasis/pathology , Magnetic Resonance Imaging , Male , Mandibular Neoplasms/diagnostic imaging , Mandibular Neoplasms/pathology , Neck , Neoplasms, Second Primary/diagnosis , Neoplasms, Second Primary/diagnostic imaging , Neoplasms, Second Primary/pathology , Odontogenic Tumors/diagnostic imaging , Odontogenic Tumors/pathology , Odontogenic Tumors/secondary , Stomach Neoplasms/surgery , Tomography, X-Ray Computed
13.
Hippocampus ; 8(3): 299-309, 1998.
Article in English | MEDLINE | ID: mdl-9662143

ABSTRACT

The synaptic modifications underlying long-term potentiation (LTP) and long-term depression (LTD) of synaptic transmission in various brain structures may result from changes in the properties of the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) subtype of glutamate receptors. In the present study, we report that treatment of rat synaptoneurosomes with increasing concentrations of phospholipase A2 (PLA2) produces a biphasic effect on AMPA receptor binding, with low concentrations causing a decrease and high concentrations an increase in agonist binding. Analysis of the saturation kinetics of 3H-AMPA binding revealed that the biphasic effect of PLA2 was due to modifications in receptor affinity and not to changes in the maximum number of binding sites for AMPA receptors. The 12-lipoxygenase inhibitors preferentially reduced PLA2-induced decrease in AMPA binding and treatment of hippocampal synaptoneurosomes with arachidonic acid (AA) or 12-HPETE, the first metabolite generated from the hydrolysis of AA by 12-lipoxygenases, decreased 3H-AMPA binding. Moreover, electrophysiological experiments indicated that the 12-lipoxygenase inhibitor baicalein totally blocked LTD formation in area CA1 of hippocampal slices. The decrease in 3H-AMPA binding elicited by low concentrations of PLA2, as well as the level of LTD, were partially reduced by AA-861, a 5-lipoxygenase inhibitor, while the cyclooxygenase inhibitor indomethacin did not prevent LTD formation or the effects of PLA2 on 3H-AMPA binding. Our results provide evidence for a possible involvement of lipoxygenase metabolites in the regulation of AMPA receptor during synaptic depression. In addition, they strongly support the idea that the same biochemical pathway, i.e., NMDA receptor activation and endogenous PLA2 stimulation, may represent a common mechanism resulting in AMPA receptor alterations for both LTP and LTD formation.


Subject(s)
Hippocampus/drug effects , Hippocampus/metabolism , Phospholipases A/pharmacology , Receptors, AMPA/physiology , Animals , Arachidonic Acid/pharmacology , Calcium/pharmacology , Cyclooxygenase Inhibitors/pharmacology , Enzyme Activation/physiology , Excitatory Amino Acid Agonists/metabolism , In Vitro Techniques , Lipoxygenase Inhibitors/pharmacology , Male , Phospholipases A2 , Protein Kinases/metabolism , Rats , Rats, Sprague-Dawley , Receptors, AMPA/metabolism , Synaptosomes/drug effects , Synaptosomes/metabolism , alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid/metabolism
14.
Hear Res ; 115(1-2): 184-96, 1998 Jan.
Article in English | MEDLINE | ID: mdl-9472747

ABSTRACT

A computational model of the organ of Corti is described to assist in the interpretation of electrophysiological data concerning the role of the K+ channels residing in the basolateral membrane of cochlear hair cells. Recent in vivo data from Van Emst et al. (Hear. Res. 88, 27-35 (1995); Hear. Res. 102, 70-80 (1996)) about the effects of selective blocking of K+ channels indicate that these channels affect the magnitude of the summating potential. In order to understand the nature of this effect, the model of Dallos (Hear. Res. 14, 281-291 (1984)) was extended to account for the voltage- and time-dependent properties of the K+ channels in the basolateral membrane of the inner hair cell (IHC) (Kros and Crawford, J. Physiol. 421, 262-291 (1990)). The model shows that the K+ channels induce a shift in the mean IHC basolateral conductance when high-frequency stimuli are present. As a result, cochlear transduction shifts to a different electrical operating state and this is the source of a marked decrease in the stimulus-evoked DC response of the IHC. Extracellularly, in contrast, the magnitude of the DC response increases slightly. At low frequencies, the K+ channels respond to the stimulus waveform on a cycle-by-cycle basis. The waveform distortion associated with this dynamic basolateral impedance induces a further decrease in the intracellular stimulus-evoked DC response of the IHC. Thus, K+ channels in the IHC appear to be directly involved in the generation of the DC receptor potential at low frequencies, but at high frequencies they simply modify the size of the DC response.


Subject(s)
Cochlear Microphonic Potentials/physiology , Computer Simulation , Hair Cells, Auditory, Inner/physiology , Organ of Corti/physiology , Potassium Channels/physiology , Acoustic Stimulation , Animals , Cell Membrane/physiology , Evoked Potentials, Auditory, Brain Stem/physiology , Membrane Potentials/physiology , Models, Biological , Otoacoustic Emissions, Spontaneous/physiology , Patch-Clamp Techniques
15.
Brain Res ; 740(1-2): 337-45, 1996 Nov 18.
Article in English | MEDLINE | ID: mdl-8973832

ABSTRACT

The effects of phosphatidylserine (PS) on the binding properties of the AMPA (alpha-amino-3-hydroxy-5-methylisoxazolepropionic acid) and NMDA (N-methyl-D-aspartate) subtypes of glutamate receptors were analyzed by quantitative autoradiography of [3H]AMPA, [3H]6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and [3H]glutamate binding on rat brain tissue sections. Preincubation of brain sections with PS produced an increase in [3H]AMPA binding without modifying the binding properties of [3H]CNQX, an antagonist of AMPA receptors. This effect of PS appeared to be specific for the AMPA subtype of glutamate receptors as the same treatment did not modify [3H]glutamate binding to the NMDA receptors. Furthermore, the PS-induced increase in [3H]AMPA binding was different in various brain structures, being larger in the molecular layer of the cerebellum and almost absent in the striatum. Preincubation with calcium also augmented [3H]AMPA binding, and the lack of additivity of the effects of calcium and PS on [3H]AMPA binding strongly suggests that both treatments share a common mechanism(s) for producing increased agonist binding. Finally, the effect of PS on AMPA receptor properties was markedly reduced in rat brain sections prepared from neonatal rats at a developmental stage that is normally characterized by the absence of LTP expression in certain brain regions. The present data are consistent with the hypothesis that alteration in the lipid composition of synaptic membranes may be an important mechanism for regulating AMPA receptor properties, which could be involved in producing long-lasting changes in synaptic operation.


Subject(s)
Animals, Newborn/physiology , Brain/drug effects , Phosphatidylserines/pharmacology , Receptors, Glutamate/drug effects , Animals , Binding, Competitive , Dose-Response Relationship, Drug , Rats , Rats, Sprague-Dawley
16.
J Acoust Soc Am ; 98(4): 1890-4, 1995 Oct.
Article in English | MEDLINE | ID: mdl-7593913

ABSTRACT

A software package with a modular architecture has been developed to support perceptual modeling of the fine-grain spectro-temporal information observed in the auditory nerve. The package contains both functional and physiological modules to simulate auditory spectral analysis, neural encoding, and temporal integration, including new forms of periodicity-sensitive temporal integration that generate stabilized auditory images. Combinations of the modules enable the user to approximate a wide variety of existing, time-domain, auditory models. Sequences of auditory images can be replayed to produce cartoons of auditory perceptions that illustrate the dynamic response of the auditory system to everyday sounds.


Subject(s)
Auditory Perception , Equipment Design , Software , Basilar Membrane , Ear, Middle/physiology , Humans , Models, Biological , Time Factors
17.
J Acoust Soc Am ; 95(1): 331-42, 1994 Jan.
Article in English | MEDLINE | ID: mdl-8120244

ABSTRACT

A dual analog/digital model of the ascending path through the entire auditory periphery is described. The analog representation consists of the concatenation of electrical circuit submodels for (a) the diffraction of the external ear system; (b) the propagation through the concha and auditory canal; (c) the transmission through the middle ear; (d) the basilar membrane motion and cochlear hydrodynamics; (e) the fast motile mechanism of the outer hair cells; and (f) the neural transduction process of the inner hair cells. Time-domain numerical solutions are obtained by applying the technique of wave digital filtering onto the resulting analog circuit. The present version of the model reproduces the sound pressure gain at the eardrum for lateral sound incidence, the vibration characteristics of the stapes, and the low-frequency attenuation provided by the stapedial muscle. Source elements in the cochlear module provide level-dependent basilar membrane tuning curves leading to dynamic compression of input signals near the characteristic frequency/place. The output is the tonotopic distribution of firing activity in the auditory nerve. A companion article addresses the modeling of the descending paths [C. Giguère and P. C. Woodland, J. Acoust, Soc. Am. 94, 343-349 (1993)].


Subject(s)
Cochlea/physiology , Computer Simulation , Ear Canal/physiology , Ear, External/physiology , Hearing/physiology , Speech Perception/physiology , Auditory Pathways/physiology , Basilar Membrane/physiology , Computers, Analog , Evoked Potentials, Auditory/physiology , Hair Cells, Auditory, Inner/physiology , Hair Cells, Auditory, Outer/physiology , Humans , Neural Networks, Computer , Pitch Perception/physiology , Synaptic Transmission/physiology , Vestibulocochlear Nerve/physiology
18.
J Acoust Soc Am ; 95(1): 343-9, 1994 Jan.
Article in English | MEDLINE | ID: mdl-8120245

ABSTRACT

The auditory model described in Giguère and Woodland [J. Acoust. Soc. Am. 94, 331-342 (1993)] is applied to the simulation of the descending paths to the peripheral ear. An external feedback unit regulates the average firing rate of inner hair cell afferent fibers via a simplified modeling of the dynamics of the acoustic reflex to the middle ear and of the slow efferent innervation of the outer hair cells. The terminal effector of the acoustic reflex system is the stapedial muscle which stiffens the middle ear and reduces vibration of the stapes up to 15 dB below 1000 Hz. The control function of the efferent system is realized by modulating the coupling gain between the inner hair cell cilia and the surrounding subtectoral fluid over a range of 24 dB. The efferent system has the capability to regulate firing rate over selective tonotopic regions of the auditory nerve. It operates at a lower target rate and has a faster response than the acoustic reflex system. The feedback unit leads to dynamic compression of speech cochleograms along both the time and frequency axes.


Subject(s)
Computer Simulation , Hair Cells, Auditory, Inner/physiology , Hearing/physiology , Reflex, Acoustic/physiology , Speech Perception/physiology , Efferent Pathways/physiology , Hair Cells, Auditory, Outer/physiology , Humans , Olivary Nucleus/physiology , Pitch Perception/physiology , Sound Spectrography , Stapes/physiology , Synaptic Transmission/physiology , Tectorial Membrane/physiology , Vestibulocochlear Nerve/physiology
19.
J Acoust Soc Am ; 94(2 Pt 1): 769-76, 1993 Aug.
Article in English | MEDLINE | ID: mdl-8370883

ABSTRACT

This research assessed the ability of human listeners to localize one-third octave noise bands in the horizontal plane. The effects of reverberation time (absorbent versus reverberant room), stimulus center frequency (500, 1000, 2000, and 4000 Hz), stimulus rise/decay time (5 vs 200 ms) and speaker array (frontal versus lateral) were investigated for four subjects using a forced-choice speaker-identification paradigm. Sound localization scores were consistently lower in the reverberant room than in the absorbent room. They also revealed strong frequency and azimuthal effects. The benefit of a shorter rise/decay time was small and limited to low frequencies. The identification of a speaker position depended strongly upon the array in which it was embedded, primarily because localization in the lateral array led to frequency-dependent front/back confusions and response bias. The results also illustrated the importance of choosing a coordinate system based on the auditory cone-of-confusion to analyze localization data for speaker arrays spanning the aural axis.


Subject(s)
Sound Localization , Auditory Perception , Female , Humans , Male
20.
Scand Audiol ; 22(2): 71-85, 1993.
Article in English | MEDLINE | ID: mdl-8322001

ABSTRACT

Auditory perception with hearing protectors was assessed in three groups of subjects, two with normal hearing, but differing in age, and one with moderate bilateral sensorineural hearing loss. Individuals were tested with the ears unoccluded, and fitted with each of two level-dependent ear muffs and their conventional level-independent counterparts. One of the former devices provided limited amplification. In each of these five ear conditions, the threshold of audibility for one-third octave noise bands centered at 500, 1,000, 2,000 and 4,000 Hz, consonant discrimination, and word recognition were measured in quiet and in a continuous impulse noise background. The results showed that the attenuation of sounds (i.e. the difference between protected and unoccluded thresholds) in quiet did not vary as a function of age or hearing loss for any of the four protectors. In noise, the difference between protected and unoccluded listening was close to zero, as long as hearing was normal. With hearing loss as a factor, there was a significant increment in the protected threshold, the amount determined by the device. Word recognition in quiet was adversely affected in normal-hearing listeners by the three attenuating devices but improved in noise relative to unoccluded listening. Amplification had a deleterious effect for both consonant discrimination and word recognition in noise. In hearing-impaired listeners, speech perception was impeded by all four muffs but less so in quiet with limited amplification.


Subject(s)
Aging/physiology , Ear Protective Devices , Hearing Loss, Sensorineural/diagnosis , Adult , Age Factors , Female , Humans , Male , Middle Aged , Noise/adverse effects , Perceptual Masking , Speech Discrimination Tests , Speech Perception
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