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Biomedical subjects

R Netsell

Publications and source records attributed to R Netsell.

At least 19 recordsLinked to original sources
PubMed1992

Vocalizations in the cat: behavioral methodology and spectrographic analysis.

Attempts to understand the neural mechanisms underlying mammalian vocal behaviors, including speech, require study of the neural activity and anatomy of vocalization-controlling brain structures. Such studies necessitate the application of invasive neurobiological techniques in animal models. In the current study, cats are used in the development of an animal model of vocal tract control. The animals are instrumentally conditioned to vocalize for food reward. Acquisition of this task can occur within a few minutes, although additional training generally is required to solidly establish the behavior and to train subjects to produce consistently high rates of vocalization for prolonged periods of time. Following training, animals can generally sustain a rate of two calls per minute for a period of over two hours. Optimal task performance is partly dependent on motivation level. Although there is considerable variation between animals, the vocalizations produced have an average duration of 600 ms and a fundamental frequency of around 500 Hz. In addition, during a typical vocalization, there are dynamic variations of about 150 Hz for fundamental frequency and 17 dB for sound intensity. These variations provide opportunities for relating neural and muscular activity to different aspects of the vocal behavior they control. Based on a number of considerations, the model and techniques discussed here probably are most applicable to studying the neurobiology of sub-cortical nuclei subserving vocal control. Similar mechanisms might well be present in other species, including humans. Thus, data obtained from study of this model may be applicable to understanding the processes underlying vocal tract control during human speech.

Animals↗
PubMed1992

Factors influencing neural activity in parabrachial regions during cat vocalizations.

The parabrachial nucleus in mammals is intimately connected with other vocalization controlling brainstem structures. It, along with ventromedially adjacent structures, also has been identified as the pneumotaxic center, and as such shows strong respiratory related activity in the anesthetized cat. The current study examines the neuronal activity in cat parabrachial regions during production of instrumentally conditioned vocalizations. Most of the units in our sample show considerable activity during periods between vocalizations. For many units, firing rate fluctuates during the respiratory cycle, although apparently not as strongly as reported in the decerebrate cat. Also, there is often strong phasic activity during periods where animals are licking to ingest their food rewards. During the peri-vocalization period, various neural activity patterns can be recorded. Most common is an activity increase during the vocalization itself. Moreover, in some units, this activity increase has an auditory component. A smaller number of units show other activity patterns, including a suppression of activity during vocalization and activity increases preceding the vocalization. Overall, our results suggest that the parabrachial region's involvement in vocal control is quite complex, involving convergence of respiratory, acoustic, vocalization-related, and perhaps somatosensory influences.

Acoustic Stimulation↗
PubMed1987

Phonetic development in identical twins differing in auditory function.

The subjects of this report are identical (monozygotic) twin boys who differ in auditory function. One has normal hearing; the other has a profound hearing loss bilaterally. These boys offered a rare opportunity to study the effects of hearing loss on vocal development with reasonable control over environmental and genetic factors. This initial report focuses on their vocal development over the sampled ages of 8, 12, and 15 months. Acoustic-phonetic differences in the babbling of the two boys were evident in the 8-month sample (the first recording opportunity), and some differences between them became greater over the succeeding samples at 12 and 15 months. The major differences were in the formant patterns of vocalic elements; the frequency of occurrence of fricatives, affricates, and trills; histograms of syllable type; and variation in vowel usage. The data hold implications for the early identification of infants at risk for communication disorder and for the understanding of auditory-motor processes in phonetic development during infancy.

Child Language↗
PubMed1986

Differential fine force control of the upper and lower lips.

From a review of the literature, it was hypothesized that the upper lip and lower lip are differentially controlled by separate, but interacting, neuronal connectivities. A normal data base was developed for select measures of fine force control occurring within physiologic levels presumably involved in speech production. Fine force control in the lower lip was found to be significantly more stable, and recruited at higher rates than the upper lip. Explanations are presented for the lower lip superiority on these measures and observations are made concerning the use of these rudimentary physiologic measures in studies of the dysarthrias.

Adolescent↗
PubMed1986

Pediatric videonasoendoscopy for speech and voice evaluation.

Many otolaryngologists and speech clinicians have found videofiberoptic evaluations to be invaluable for assessment of velopharyngeal and laryngeal function in adults. However, many professionals question the feasibility of routine use of these procedures in the pediatric population. This article describes a method for successful completion of videonasoendoscopic speech and voice evaluations of children as young as 3 years of age. The importance of the ENT/speech team is emphasized in both the collection and interpretation of data. In addition, contributions of videonasoendoscopic observations to diagnosis, medical treatment, and therapy for speech and voice disorders are discussed.

Child↗
PubMed1979

Acoustic characteristics of dysarthria associated with cerebellar disease.

The speech of five individuals with cerebellar disease and ataxic dysarthria was studied with acoustic analyses of CVC words, words of varying syllabic structure (stem, stem plus suffix, stem plus two suffixes), simple sentences, the Rainbow Passage, and conversation. The most consistent and marked abnormalities observed in spectrograms were alterations of the normal timing pattern, with prolongation of a variety of segments and a tendency toward equalized syllable durations. Vowel formant structure in the CVC words was judged to be essentially normal except for transitional segments. The greater the severity of the dysarthria, the greater the number of segments lengthened and the degree of lengthening of individual segments. The ataxic subjects were inconsistent in durational adjustments of the stem syllable as the number of syllables in a word was varied and generally made smaller reductions than normal subjects as suffixes were added. Disturbances of syllable timing frequently were accompanied by abnormal contours of fundamental frequency, particularly monotone and syllable-falling patterns. These dysprosodic aspects of ataxic dysarthria are discussed in relation to cerebellar function in motor control.

Aged↗
PubMed1979

Dysarthria in adults: physiologic approach to rehabilitation.

A case study is used to illustrate a physical approach to the speech rehabilitation of adults with dysarthria. The approach emphasizes the component-by-component analysis of the peripheral speech mechanism, where the selection and sequencing of treatment procedures follow directly from the physiologic nature and severity of involvement in each component. The selection and sequencing of procedures also are conditioned by the inherent physical interdependencies of these component parts. Several biofeedback procedures of our own are incorporated that have not been reported previously. The case illustration is of a young man injured in an auto accident whose speech intelligibility improves from approximately 5-10% to 95% during the rehabilitation period. Effects of treatment upon individual components of the speech mechanism are illustrated.

Adult↗
PubMed1978

Articulatory abnormalities in athetoid cerebral palsy.

This report presents cinefluorographic data on the articulation of isolated vowels, VCV nonsense utterances, and short sentences by five subjects with athetoid cerebral palsy. Articulatory abnormalities were identified from tracings of vocal tract shapes and from displacement-by-time plots of articulatory events. The most frequent abnormalities were large ranges of jaw movement, inappropriate positioning of the tongue for various phonetic segments (especially because of a reduced range of tongue movement in the anteroposterior dimension), intermittency of velopharyngeal closure caused by an instability of velar elevation, prolonged transition times for articulatory movements, and retrusion of the lower lip. The speech disorder associated with athetosis is considered with respect to a model of motor learning.

Adult↗
PubMed1976

Paroxysmal ataxic dysarthria.

This report reviews 13 cases in which a dysarthria appeared, remitted, and reappeared within seconds. The speech pattern of each case was characteristic of ataxic dysarthria. A cinefluorographic film for one of the subjects provided a rare opportunity to study the articulatory dynamics of this disorder. Multiple sclerosis either was given as a diagnosis or was strongly suspected in each case, and carbamazepine has been an effective treatment. Speculations concerning the origin of the paroxysmal and ataxic character of the dysarthria are presented along with a preliminary checklist for identifying the disorder.

Acoustics↗
PubMed1976

A new technique for measuring velopharyngeal orifice area during sustained vowel production: an application of aerodynamic forced oscillation principles.

A new technique for measuring velopharyngeal orifice area during sustained vowel production is described. The technique is based on a simple oscillatory flow balancing procedure between two aerodynamic branches, a mechanical model of the human upper airway and the subject's upper airway. The area of the velopharyngeal orifice in the model is adjusted until identical oscillatory flows traverse it and the subject's velopharyngeal orifice in response to a common forced oscillatory pressure. When identical oscillatory flows are observed, the area of the adjusted orifice is taken as a measure of the area of the subject's velopharyngeal orifice.

Humans↗
PubMed1975

A case study of an ataxic dysarthric: cineradiographic and spectrographic observations.

Cineradiographic and spectrographic analyses were performed to study the speech production of a subject who presented the classical neurologic signs of cerebellar lesion and who had speech characteristics like those that have been reported for ataxic dysarthria. These analyses were conducted with special attention to the deviant perceptual dimensions that have been described for ataxic speech. Examination of the cineradiographic and spectrographic records revealed conspicuous abnormalities in speaking rate, stress patterns, articulatory placements for both vowels and consonants, velocities of articulator movements, and fundamental frequency contours. In general, our physiological and acoustic observations of ataxic dysarthria were compatible with existing perceptual descriptions of this condition. The data for the subject are discussed in the light of current hypotheses concerning cerebellar participation in the regulation of skilled movement. Particular suggestions are made concerning the nature of the neuromuscular abnormalities that may underlie the aberrant motorics of ataxic dysarthria.

Cerebellar Ataxia↗
PubMed1975

Acceleration and weakness in parkinsonian dysarthria.

This report presents some of the underlying neuromuscular mechanisms of dysarthric speech production as they are manifested in selected individuals with parkinsonism. Earlier explanations of parkinsonian dysarthria emphasized that the balanced hypertonus of rigidity formed the basis of reduced range of movements in speech. The present data reveal two problems in the neuromuscular control signals that can result in a reduced range of speech movements in the absence of rigidity. These neuromuscular problems are described as acceleration and weakness. The implication of these findings for the evaluation and treatment of parkinsonian dysarthria is discussed.

Humans↗
PubMed1975

Cineradiographic assessment of articulatory mobility in the dysarthrias.

This paper describes cineradiographic techniques for the assessment of articulatory mobility in dysarthric subjects. Sample data for the mobility ranges of articulatory points on the tongue, lower lip, and jaw are presented for four normal speakers and four dysarthric speakers. In addition, fleshpoint displacements during the articulatory movements of the dysarthric subjects are used to illustrate abnormalities in the range, rate, and direction of speech movements. Discussion of the point-parameterized cineradiographic data emphasizes possibilities for the clinical evaluation of dysarthric impairments.

Cineradiography↗