Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 59
Filter
1.
Public Health ; 217: 89-94, 2023 Apr.
Article in English | MEDLINE | ID: mdl-36867987

ABSTRACT

OBJECTIVES: This national survey aimed to explore how existing pandemic preparedness plans (PPP) accounted for the demands placed on infection prevention and control (IPC) services in acute and community settings in England during the first wave of the COVID-19 pandemic. STUDY DESIGN: This was a cross-sectional survey of IPC leaders working within National Health Service Trusts or clinical commissioning groups/integrated care systems in England. METHODS: The survey questions related to organisational COVID-19 preparedness pre-pandemic and the response provided during the first wave of the pandemic (January to July 2020). The survey ran from September to November 2021, and participation was voluntary. RESULTS: In total, 50 organisations responded. Seventy-one percent (n = 34/48) reported having a current PPP in December 2019, with 81% (n = 21/26) indicating their plan was updated within the previous 3 years. Around half of IPC teams were involved in previous testing of these plans via internal and multi-agency tabletop exercises. Successful aspects of pandemic planning were identified as command structures, clear channels of communication, COVID-19 testing, and patient pathways. Key deficiencies were lack of personal protective equipment, difficulties with fit testing, keeping up to date with guidance, and insufficient staffing. CONCLUSIONS: Pandemic plans need to consider the capability and capacity of IPC services to ensure they can contribute their critical knowledge and expertise to the pandemic response. This survey provides a detailed evaluation of how IPC services were impacted during the first wave of the pandemic and identifies key areas, which need to be included in future PPP to better manage the impact on IPC services.


Subject(s)
COVID-19 , Humans , COVID-19/epidemiology , Pandemics/prevention & control , COVID-19 Testing , Cross-Sectional Studies , State Medicine , Infection Control
3.
Dis Esophagus ; 29(7): 724-733, 2016 Oct.
Article in English | MEDLINE | ID: mdl-27731547

ABSTRACT

We report data-simple descriptions of patient characteristics, cancer categories, and non-risk-adjusted survival-for patients with pathologically staged cancer of the esophagus and esophagogastric junction after resection or ablation with no preoperative therapy from the Worldwide Esophageal Cancer Collaboration (WECC). Thirty-three institutions from six continents submitted de-identified data using standard definitions: demographics, comorbidities, clinical cancer categories, and all-cause mortality from first management decision. Of 13,300 patients, 5,631 had squamous cell carcinoma, 7,558 adenocarcinoma, 85 adenosquamous carcinoma, and 26 undifferentiated carcinoma. Patients were older (62 years) men (80%) with normal body mass index (51%), little weight loss (1.8 kg), 0-2 ECOG performance status (83%), and a history of smoking (70%). Cancers were pT1 (24%), pT2 (15%), pT3 (50%), pN0 (52%), pM0 (93%), and pG2-G3 (78%); most involved distal esophagus (71%). Non-risk-adjusted survival for both squamous cell carcinoma and adenocarcinoma was monotonic and distinctive across pTNM. Survival was more distinctive for adenocarcinoma than squamous cell carcinoma when pT was ordered by pN. Survival for pTis-1 adenocarcinoma was better than for squamous cell carcinoma, although monotonic and distinctive for both. WECC pathologic staging data is improved over that of the 7th edition, with more patients studied and patient and cancer variables collected. These data will be the basis for the 8th edition cancer staging manuals following risk adjustment for patient, cancer, and treatment characteristics, and should direct 9th edition data collection. However, the role of pure pathologic staging as the principal point of reference for esophageal cancer staging is waning.


Subject(s)
Ablation Techniques/mortality , Carcinoma/pathology , Esophageal Neoplasms/pathology , Esophagectomy/mortality , Neoplasm Staging/mortality , Adult , Aged , Carcinoma/mortality , Carcinoma/surgery , Esophageal Neoplasms/mortality , Esophageal Neoplasms/surgery , Esophagogastric Junction/pathology , Esophagogastric Junction/surgery , Female , Humans , Intersectoral Collaboration , Male , Middle Aged , Prognosis , Risk Assessment/methods
4.
Dis Esophagus ; 29(7): 707-714, 2016 Oct.
Article in English | MEDLINE | ID: mdl-27731549

ABSTRACT

To address uncertainty of whether clinical stage groupings (cTNM) for esophageal cancer share prognostic implications with pathologic groupings after esophagectomy alone (pTNM), we report data-simple descriptions of patient characteristics, cancer categories, and non-risk-adjusted survival-for clinically staged patients from the Worldwide Esophageal Cancer Collaboration (WECC). Thirty-three institutions from six continents submitted data using variables with standard definitions: demographics, comorbidities, clinical cancer categories, and all-cause mortality from first management decision. Of 22,123 clinically staged patients, 8,156 had squamous cell carcinoma, 13,814 adenocarcinoma, 116 adenosquamous carcinoma, and 37 undifferentiated carcinoma. Patients were older (62 years) men (80%) with normal body mass index (18.5-25 mg/kg2 , 47%), little weight loss (2.4 ± 7.8 kg), 0-1 ECOG performance status (67%), and history of smoking (67%). Cancers were cT1 (12%), cT2 (22%), cT3 (56%), cN0 (44%), cM0 (95%), and cG2-G3 (89%); most involved the distal esophagus (73%). Non-risk-adjusted survival for squamous cell carcinoma was not distinctive for early cT or cN; for adenocarcinoma, it was distinctive for early versus advanced cT and for cN0 versus cN+. Patients with early cancers had worse survival and those with advanced cancers better survival than expected from equivalent pathologic categories based on prior WECC pathologic data. Thus, clinical and pathologic categories do not share prognostic implications. This makes clinically based treatment decisions difficult and pre-treatment prognostication inaccurate. These data will be the basis for the 8th edition cancer staging manuals following risk adjustment for patient characteristics, cancer categories, and treatment characteristics and should direct 9th edition data collection.


Subject(s)
Carcinoma/pathology , Esophageal Neoplasms/pathology , Neoplasm Staging/mortality , Adult , Aged , Carcinoma/mortality , Carcinoma/surgery , Esophageal Neoplasms/mortality , Esophageal Neoplasms/surgery , Esophagectomy/mortality , Female , Humans , Intersectoral Collaboration , Male , Middle Aged , Prognosis , Risk Assessment/methods
5.
Dis Esophagus ; 29(7): 715-723, 2016 Oct.
Article in English | MEDLINE | ID: mdl-27731548

ABSTRACT

To address uncertainty of whether pathologic stage groupings after neoadjuvant therapy (ypTNM) for esophageal cancer share prognostic implications with pathologic groupings after esophagectomy alone (pTNM), we report data-simple descriptions of patient characteristics, cancer categories, and non-risk-adjusted survival-for pathologically staged cancers after neoadjuvant therapy from the Worldwide Esophageal Cancer Collaboration (WECC). Thirty-three institutions from six continents submitted data using variables with standard definitions: demographics, comorbidities, clinical cancer categories, and all-cause mortality from first management decision. Of 7,773 pathologically staged neoadjuvant patients, 2,045 had squamous cell carcinoma, 5,686 adenocarcinoma, 31 adenosquamous carcinoma, and 11 undifferentiated carcinoma. Patients were older (61 years) men (83%) with normal (40%) or overweight (35%) body mass index, 0-1 Eastern Cooperative Oncology Group performance status (96%), and a history of smoking (69%). Cancers were ypT0 (20%), ypT1 (13%), ypT2 (18%), ypT3 (44%), ypN0 (55%), ypM0 (94%), and G2-G3 (72%); most involved the distal esophagus (80%). Non-risk-adjusted survival for yp categories was unequally depressed, more for earlier categories than later, compared with equivalent categories from prior WECC data for esophagectomy-alone patients. Thus, survival of patients with ypT0-2N0M0 cancers was intermediate and similar regardless of ypT; survival for ypN+ cancers was poor. Because prognoses for ypTNM and pTNM categories are dissimilar, prognostication should be based on separate ypTNM categories and groupings. These data will be the basis for the 8th edition cancer staging manuals following risk adjustment for patient, cancer, and treatment characteristics and should direct 9th edition data collection.


Subject(s)
Carcinoma/pathology , Esophageal Neoplasms/pathology , Neoadjuvant Therapy/mortality , Neoplasm Staging/mortality , Adult , Aged , Carcinoma/mortality , Carcinoma/therapy , Esophageal Neoplasms/mortality , Esophageal Neoplasms/therapy , Female , Humans , Intersectoral Collaboration , Male , Middle Aged , Prognosis , Risk Assessment/methods
6.
Epidemiol Infect ; 143(6): 1129-38, 2015 Apr.
Article in English | MEDLINE | ID: mdl-25084481

ABSTRACT

Data were extracted from the case records of UK patients admitted with laboratory-confirmed influenza A(H1N1)pdm09. White and non-White patients were characterized by age, sex, socioeconomic status, pandemic wave and indicators of pre-morbid health status. Logistic regression examined differences by ethnicity in patient characteristics, care pathway and clinical outcomes; multivariable models controlled for potential confounders. Whites (n = 630) and non-Whites (n = 510) differed by age, socioeconomic status, pandemic wave of admission, pregnancy, recorded obesity, previous and current smoking, and presence of chronic obstructive pulmonary disease. After adjustment for a priori confounders non-Whites were less likely to have received pre-admission antibiotics [adjusted odds ratio (aOR) 0·43, 95% confidence interval (CI) 0·28-0·68, P < 0·001) but more likely to receive antiviral drugs as in-patients (aOR 1·53, 95% CI 1·08-2·18, P = 0·018). However, there were no significant differences by ethnicity in delayed admission, severity at presentation for admission, or likelihood of severe outcome.


Subject(s)
Ethnicity/statistics & numerical data , Influenza A Virus, H1N1 Subtype , Influenza, Human/therapy , Adolescent , Adult , Age Factors , Aged , Child , Child, Preschool , Critical Pathways/statistics & numerical data , Female , Healthcare Disparities/statistics & numerical data , Hospitalization/statistics & numerical data , Humans , Infant , Male , Middle Aged , Patient Outcome Assessment , Racial Groups/statistics & numerical data , Sex Factors , Socioeconomic Factors , United Kingdom/epidemiology , Young Adult
7.
Thorax ; 65(7): 645-51, 2010 Jul.
Article in English | MEDLINE | ID: mdl-20627925

ABSTRACT

BACKGROUND: During the first wave of pandemic H1N1 influenza in 2009, most cases outside North America occurred in the UK. The clinical characteristics of UK patients hospitalised with pandemic H1N1 infection and risk factors for severe outcome are described. METHODS: A case note-based investigation was performed of patients admitted with confirmed pandemic H1N1 infection. RESULTS: From 27 April to 30 September 2009, 631 cases from 55 hospitals were investigated. 13% were admitted to a high dependency or intensive care unit and 5% died; 36% were aged <16 years and 5% were aged > or = 65 years. Non-white and pregnant patients were over-represented. 45% of patients had at least one underlying condition, mainly asthma, and 13% received antiviral drugs before admission. Of 349 with documented chest x-rays on admission, 29% had evidence of pneumonia, but bacterial co-infection was uncommon. Multivariate analyses showed that physician-recorded obesity on admission and pulmonary conditions other than asthma or chronic obstructive pulmonary disease (COPD) were associated with a severe outcome, as were radiologically-confirmed pneumonia and a raised C-reactive protein (CRP) level (> or = 100 mg/l). 59% of all in-hospital deaths occurred in previously healthy people. CONCLUSIONS: Pandemic H1N1 infection causes disease requiring hospitalisation of previously fit individuals as well as those with underlying conditions. An abnormal chest x-ray or a raised CRP level, especially in patients who are recorded as obese or who have pulmonary conditions other than asthma or COPD, indicate a potentially serious outcome. These findings support the use of pandemic vaccine in pregnant women, children <5 years of age and those with chronic lung disease.


Subject(s)
Hospitalization/statistics & numerical data , Influenza A Virus, H1N1 Subtype , Influenza, Human/diagnosis , Adolescent , Adult , Age Distribution , Age Factors , Aged , Aged, 80 and over , Antiviral Agents/therapeutic use , Child , Child, Preschool , Critical Care/statistics & numerical data , Disease Outbreaks , England/epidemiology , Female , Humans , Infant , Influenza, Human/drug therapy , Influenza, Human/epidemiology , Length of Stay/statistics & numerical data , Male , Middle Aged , Pneumonia, Viral/epidemiology , Pneumonia, Viral/virology , Prognosis , Risk Factors , Treatment Outcome , Young Adult
8.
J Clin Virol ; 40(3): 241-4, 2007 Nov.
Article in English | MEDLINE | ID: mdl-17920332

ABSTRACT

BACKGROUND: Nasopharyngeal secretions aspirated from infants with bronchiolitis (NPA) are a valuable resource for the study of virus dynamics and local inflammatory responses, however samples are small and difficult to manipulate. OBJECTIVES: To improve yield of NPA from infants. To establish if removal of the cellular component of NPA affects quantification of human metapneumovirus (hMPV) or human respiratory syncytial virus (hRSV) genome. STUDY DESIGN: Weight of NPA collected into traps from 30 infants was compared with that collected in trap plus catheter and washed through with saline from another 30 infants. hMPV (n=33) and hRSV (n=30) genome was measured by reverse-transcribed real-time polymerase chain reaction (RT-RT-PCR) in paired whole and cell-free NPA collected by the improved method. RESULTS: The improved method of NPA collection gave near two-fold greater weight (p = 0.002) of NPA (mean = 0.52 g (S.D. = 0.30 g)) than the traditional method (0.32 g (S.D. 0.19)). There was strong agreement and no significant difference between viral load measured in whole and cell-free fractions of NPA for both viruses (samples (n), correlation coefficient (cc) and significance (p)); hMPV (n=33, cc=0.938, p<0.001) and hRSV (n=30, cc=0.977 and p<0.001). CONCLUSIONS: The majority of hRSV and hMPV in nasal secretions is not associated with cells. Removal of the cellular component of NPA does not interfere with quantification of hRSV and hMPV.


Subject(s)
Metapneumovirus/isolation & purification , Nasal Lavage Fluid/cytology , Nasal Lavage Fluid/virology , Respiratory Syncytial Virus, Human/isolation & purification , Specimen Handling/methods , Bronchiolitis, Viral/virology , Humans , Infant , Metapneumovirus/genetics , Paramyxoviridae Infections/virology , RNA, Viral/analysis , RNA, Viral/isolation & purification , Respiratory Syncytial Virus Infections/virology , Respiratory Syncytial Virus, Human/genetics , Reverse Transcriptase Polymerase Chain Reaction , Viral Load
9.
J Wound Care ; 12(5): 165-9, 2003 May.
Article in English | MEDLINE | ID: mdl-12784597

ABSTRACT

Treatment and care given to patients should be evidence-based, but research results based on fraudulent findings can have a serious impact on care. This paper examines how fraud may be perpetuated and discusses standards for robust research.


Subject(s)
Scientific Misconduct , Authorship , Ethics, Institutional , Humans , Research Support as Topic
10.
J Neurophysiol ; 86(3): 1113-30, 2001 Sep.
Article in English | MEDLINE | ID: mdl-11535662

ABSTRACT

Prior studies of dynamic conditioning have focused on modulation of binaural localization cues, revealing that the responses of inferior colliculus (IC) neurons to particular values of interaural phase and level disparities depend critically on the context in which they occur. Here we show that monaural frequency transitions, which do not simulate azimuthal motion, also condition the responses of IC neurons. We characterized single-unit responses to two frequency transition stimuli: a glide stimulus comprising two tones linked by a linear frequency sweep (origin-sweep-target) and a step stimulus consisting of one tone followed immediately by another (origin-target). Using sets of glide and step stimuli converging on a common target, we constructed conditioned response functions (RFs) depicting the variability in the response to an identical stimulus as a function of the preceding origin frequency. For nearly all cells, the response to the target depended on the origin frequency, even for origins outside the excitatory frequency response area of the cell. Results from conditioned RFs based on long (2-4 s) and short (200 ms) duration step stimuli indicate that conditioning effects can be induced in the absence of the dynamic sweep, and by stimuli of relatively short duration. Because IC neurons are tuned to frequency, changes in the origin frequency often change the "effective" stimulus duty cycle. In many cases, the enhancement of the target response appeared related to the decrease in the "effective" stimulus duty cycle rather than to the prior presentation of a particular origin frequency. Although this implies that nonselective adaptive mechanisms are responsible for conditioned responses, slightly more than half of IC neurons in each paradigm responded significantly differently to targets following origins that elicited statistically indistinguishable responses. The prevailing influence of stimulus context when discharge history is controlled demonstrates that not all the mechanisms governing conditioning depend on the discharge history of the recorded neuron. Selective adaptation among the neuron's variously tuned afferents may help engender stimulus-specific conditioning. The demonstration that conditioning effects reflect sensitivity to spectral as well as spatial stimulus contrast has broad implications for the processing of a wide range of dynamic acoustic signals and sound sequences.


Subject(s)
Auditory Perception/physiology , Conditioning, Psychological/physiology , Inferior Colliculi/physiology , Acoustic Stimulation , Action Potentials/physiology , Adaptation, Physiological/physiology , Animals , Gerbillinae , Inferior Colliculi/cytology , Neural Inhibition/physiology , Neurons/physiology
11.
J Neurophysiol ; 84(1): 255-73, 2000 Jul.
Article in English | MEDLINE | ID: mdl-10899201

ABSTRACT

Time-varying envelopes are a common feature of acoustic communication signals like human speech and induce a variety of percepts in human listeners. We studied the responses of 109 single neurons in the inferior colliculus (IC) of the anesthetized Mongolian gerbil to contralaterally presented sinusoidally amplitude-modulated (SAM) tones with a wide range of parameters. Modulation transfer functions (MTFs) based on average spike rate (rMTFs) showed regions of enhancement and suppression, where spike rates increased or decreased respectively as stimulus modulation depth increased. Specifically, almost all IC rMTFs could be described by some combination of a primary and a secondary region of enhancement and an intervening region of suppression, with these regions present to varying degrees in individual rMTFs. rMTF characteristics of most neurons were dependent on sound pressure level (SPL). rMTFs in most neurons with "onset" or "onset-sustained" peri-stimulus time histograms (PSTHs) in response to brief pure tones showed only a peaked primary region of enhancement. The region of suppression tended to occur in neurons with "sustained" or "pauser" PSTHs, and usually emerged at higher SPLs. The secondary region of enhancement was only found in eight neurons. The lowest modulation frequency at which the spike rate reached a clear peak ("best modulation frequency" or BMF) was measured. All but two mean BMFs lay between 0 and 100 Hz. Fifty percent of the 49 neurons tested over at least a 20-dB range of SPLs showed a BMF variation larger than 66% of their mean BMF. MTFs based on vector strength (tMTFs) showed a variety of patterns; although mostly similar to those reported from the cochlear nucleus, tMTFs of IC neurons showed higher maximum values, smaller dynamic range with depth, and a lower high-frequency limit for significant phase locking. Systematic and large increases in phase-lead commonly occurred as SPL increased. rMTFs measured at multiple carrier frequencies (F(c)s) showed that the suppressive region was not the result of sideband inhibition. There was no systematic relationship between BMF and F(c) of stimulation in the cells studied, even at low carrier frequencies. The results suggest various possible mechanisms that could create IC MTFs, and strongly support the idea that inhibitory inputs shape the rMTF by sharpening regions of enhancement and creating a suppressive region. The paucity of BMFs above 100 Hz argues against simple rate-coding schemes for pitch. Finally, any labeled line or topographic representation of modulation frequency is unlikely to be independent of SPL.


Subject(s)
Auditory Cortex/physiology , Auditory Perception/physiology , Inferior Colliculi/physiology , Acoustic Stimulation , Animals , Auditory Cortex/cytology , Electrophysiology , Gerbillinae , Inferior Colliculi/cytology , Neural Inhibition/physiology , Neurons/physiology , Pressure , Reaction Time/physiology
12.
Psychiatry ; 63(1): 65-74, 2000.
Article in English | MEDLINE | ID: mdl-10855761

ABSTRACT

Posttraumatic stress disorder (PTSD) patients with histories of cocaine and alcohol abuse (CA-PTSD) were compared with normal volunteers. Positron emission tomography (PET) scans with 15O-butanol were used to compare regional cerebral blood flow (rCBF) between the groups during rest and during an auditory continuous performance task (ACPT). CA-PTSD patients had significantly higher rCBF in right amygdala and left parahippocampal gyrus than normals during the ACPT. Normals had higher rCBF at frontal cortex during the resting scan and during the ACPT. The role of the amygdala in attention and fear conditioning suggests that increased amygdala rCBF may be related to clinical features of PTSD. Cocaine use may be associated with increased amygdala rCBF in PTSD patients. Amygdala and frontal cortex attention system components may be reciprocally related and their relative contributions to processing of neutral stimuli perturbed in CA-PTSD.


Subject(s)
Alcoholism/diagnostic imaging , Amygdala/blood supply , Cocaine-Related Disorders/diagnostic imaging , Frontal Lobe/blood supply , Stress Disorders, Post-Traumatic/diagnostic imaging , Tomography, Emission-Computed , Adult , Amygdala/diagnostic imaging , Brain Mapping , Comorbidity , Dominance, Cerebral/physiology , Frontal Lobe/diagnostic imaging , Humans , Male , Reference Values , Regional Blood Flow/physiology
14.
Eur J Neurosci ; 11(4): 1414LAST-1420, 1999 Apr.
Article in English | MEDLINE | ID: mdl-10103136

ABSTRACT

Neural responses in the adult central auditory system to binaural stimuli can be altered by preceding acoustic events, including auditory motion. To determine whether the juvenile auditory system also exhibits this feature, we have examined interaural level difference (ILD) processing in the developing gerbil. A long binaural stimulus was followed without interruption by modulation of the level difference (virtual acoustic motion), which in turn was followed smoothly by a new steady state ILD. Auditory responses of single neurons in the inferior colliculus (IC) were assessed for sensitivity to the final steady state ILD. The response of EI neurons (excited by contralateral stimulation and inhibited ipsilaterally) was examined at postnatal (P) days 17-18, P24-25, and in adult animals. In adult animals, a sudden reduction of the inhibitory stimulus level resulted in a long-lasting (median = 4.3 s) enhanced discharge rate (conditioned enhancement). In P17-18 animals, conditioned enhancement only lasted for 1.2 s. When the inhibitory stimulus level was suddenly increased, adult neurons often displayed a conditioned suppression of discharge rate (median = 4.5 s), whereas P17-18 neurons remained suppressed for a much briefer period (median = 1.2 s). Moreover, the difference between conditioned responses and control discharge rates was three-four times greater in adult neurons compared to those recorded in P17-25 animals. Because conditioned responses are sensitive to the relative balance of contralateral excitation and ipsilateral inhibition, we examined the relationship between excitatory and inhibitory thresholds. In adult animals, excitatory thresholds were an average of 12 dB lower than inhibitory thresholds, while at P17-25 excitatory and inhibitory thresholds were roughly the same. These results indicate that computational properties of juvenile and adult IC neurons differ quantitatively, and this may reflect an imbalance between excitation and inhibition. The developmental differences described herein may limit the ability of young animals to locate a sound source with the latency and accuracy of an adult.


Subject(s)
Auditory Pathways/growth & development , Conditioning, Psychological/physiology , Mesencephalon/growth & development , Neural Inhibition , Acoustic Stimulation , Analysis of Variance , Animals , Gerbillinae , Reaction Time/physiology
15.
Nurs Times ; 95(2): suppl 1-2, 1999.
Article in English | MEDLINE | ID: mdl-10067598
16.
J Neurophysiol ; 80(6): 3062-76, 1998 Dec.
Article in English | MEDLINE | ID: mdl-9862906

ABSTRACT

Transformation of binaural response properties in the ascending auditory pathway: influence of time-varying interaural phase disparity. J. Neurophysiol. 80: 3062-3076, 1998. Previous studies demonstrated that tuning of inferior colliculus (IC) neurons to interaural phase disparity (IPD) is often profoundly influenced by temporal variation of IPD, which simulates the binaural cue produced by a moving sound source. To determine whether sensitivity to simulated motion arises in IC or at an earlier stage of binaural processing we compared responses in IC with those of two major IPD-sensitive neuronal classes in the superior olivary complex (SOC), neurons whose discharges were phase locked (PL) to tonal stimuli and those that were nonphase locked (NPL). Time-varying IPD stimuli consisted of binaural beats, generated by presenting tones of slightly different frequencies to the two ears, and interaural phase modulation (IPM), generated by presenting a pure tone to one ear and a phase modulated tone to the other. IC neurons and NPL-SOC neurons were more sharply tuned to time-varying than to static IPD, whereas PL-SOC neurons were essentially uninfluenced by the mode of stimulus presentation. Preferred IPD was generally similar in responses to static and time-varying IPD for all unit populations. A few IC neurons were highly influenced by the direction and rate of simulated motion, but the major effect for most IC neurons and all SOC neurons was a linear shift of preferred IPD at high rates-attributable to response latency. Most IC and NPL-SOC neurons were strongly influenced by IPM stimuli simulating motion through restricted ranges of azimuth; simulated motion through partially overlapping azimuthal ranges elicited discharge profiles that were highly discontiguous, indicating that the response associated with a particular IPD is dependent on preceding portions of the stimulus. In contrast, PL-SOC responses tracked instantaneous IPD throughout the trajectory of simulated motion, resulting in highly contiguous discharge profiles for overlapping stimuli. This finding indicates that responses of PL-SOC units to time-varying IPD reflect only instantaneous IPD with no additional influence of dynamic stimulus attributes. Thus the neuronal representation of auditory spatial information undergoes a major transformation as interaural delay is initially processed in the SOC and subsequently reprocessed in IC. The finding that motion sensitivity in IC emerges from motion-insensitive input suggests that information about change of position is crucial to spatial processing at higher levels of the auditory system.


Subject(s)
Auditory Pathways/cytology , Sound Localization/physiology , Acoustic Stimulation , Animals , Auditory Pathways/drug effects , Cues , Gerbillinae , Inferior Colliculi/cytology , Inferior Colliculi/physiology , Olivary Nucleus/physiology , Time Factors
19.
J Neurosci ; 18(2): 794-803, 1998 Jan 15.
Article in English | MEDLINE | ID: mdl-9425020

ABSTRACT

We have recently discovered a paradoxical aftereffect associated with inhibition in the gerbil auditory midbrain. Single neurons in the inferior colliculus (IC) were assessed for sensitivity to a virtual motion stimulus produced by modulating the interaural level difference (ILD), a major cue for sound localization. The class of neuron studied was predominantly excited by contralateral stimulation and inhibited by ipsilateral stimulation. Sound pressure level was modulated trapezoidally at the ipsilateral "inhibitory" ear, whereas the contralateral "excitatory" level remained constant. When the inhibitory stimulus was decreased within a range of sound levels that maintained suppression under static conditions, an unexpected discharge was often elicited, apparently because of an aftereffect of synaptic inhibition. In contrast, when the inhibitory stimulus was increased within a range of sound levels that produced only modest suppression under static conditions, neuronal discharge was often profoundly suppressed. In many cases the "conditioned enhancement" or "conditioned suppression" persisted for several seconds after the modulation of ILD, and such conditioned responses were influenced by the modulation depth and rate. To test the effect of inhibition in the IC directly, glycine and GABA were pulsed from a glass recording pipette during a constant monaural excitatory stimulus. The acoustically elicited discharge rate was potentiated markedly if preceded immediately by the brief (0.5-10 sec) application of inhibitory transmitter. Collectively, these results revealed unusually long-lasting effects of inhibition that may establish a new range of acoustic cues to which the neuron responds best. This may have broad implications for processing ensuing auditory stimuli.


Subject(s)
Evoked Potentials, Auditory/physiology , Inferior Colliculi/physiology , Neural Inhibition , Acoustic Stimulation , Animals , Gerbillinae/physiology , Neurons/physiology , Perceptual Masking/physiology
20.
Nurs Times ; 94(48): suppl 1-2, 1998.
Article in English | MEDLINE | ID: mdl-9934174
SELECTION OF CITATIONS
SEARCH DETAIL