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Processing negativity for semantic incongruence in young and elderly persons
Ofolaryngology Head and Neck Surgery Volume 113 Number 2
nucleus (CN) has been used for rehabilitation of profoundly deaf patients who are not suitable for cochlear implants. Most of these patients were implanted with an electrode that was placed on the surface of the cochlear nucleus. Previous animal studies have demonstrated greater efficiency of a penetrating CN electrode in activating the central auditory system than a surface electrode. The objective of this work is to study and characterize the electrically evoked middle latency response (MLR) generated by stimulation through a penetrating multichannel CN electrode. A series of six pigmented guinea pigs were used i n this study. Standards of humane animal care were adhered to throughout the project. Animals were anesthetized and underwent acute implantation of a penetrating multichannel CN electrode through an occipital craniotomy approach. The stimulating electrodes consisted of a silicon substrate that supported an array of thin-film conductors. Each electrode contained five stimulation pads. Threshold, latency, and input-output functions of the electrically evoked MLR using different combinations of stimulation pads were studied. There were no differences in the threshold for eliciting the MLR between different stimulation pads. However, there were systematic differences in the latency and the amplitude of the input-output functions depending on the site of stimulation within the CN. The results support the hypothesis that discrete activation of neuronal subpopulations within the CN is possible with a multichannel penetrating microelectrode. Studies are currently underway using double-label autoradiographic techniques to further characterize the patterns of central auditory system activation using penetrating multichannel CN electrodes. This would enhance the development of prostheses and coding strategies that may provide multiple channels of information to improve patients' benefits from a CN implant. (Supported by a Deafness Research Foundation grant.) Poster 78
Processing Negativity for Semantic Incongruence in Young and Elderly Persons JENNIFER PARKER PORTER, MD (presenter), and JAMES F. JERGER, PHD, Houston, Tex.
The N400 auditory evoked response has been shown to be present during the processing of semantic incongruity. The specific aim of this project was tO compare the N400 auditory evoked response of the geriatric population with that of young persons on a sentence comprehension task in the presence of background speech competition. This study was a prospective, nonrandomized comparison of two groups of subjects: 10 elderly persons between the ages of 70 and 90 years and 10 young adults between the ages of 18 and 29 years. Two conditions were evaluated. The first condition involved sentences presented in the presence of background
Scientific Sessions- - Monday
P 101
speech competition run in the forward direction. In this mode the competition had the potential to produce both peripheral masking and central interference effects. In the second condition the target sentences were mixed with the background speech competition played in a backward mode. The average long-term spectrum remained constant, but there was no semantic distraction. The competition could only produce peripheral masking effects. Right and left ears were tested separately. In young adults the topographic brain map of the N400 response was centered in the region of the Cz and Pz electrodes. Results showed a right-ear advantage in the young population with respect to the reaction time and amp]itude of the N400 response. In the elderly subjects the amplitude of the N400 response and the reaction times were increased and the topographic distribution is altered; hnplications for evaluation of speech understanding in the elderly will be discussed. P o s t e r 79
Focal Differences in Nasal-Oral Potential Differences Between Postoperative Endoscopic Sinus Surgery Patients and Control Patients MICHAEL A. DIAS, MD (presenter), PERRYW. ALEXION, MD, THOMAS K. FITZGERALD,BS, PAUL F. CASTELLANOS, MD, JOHN F. BIEDLINGMAIER, MD, and REBECCA BASCOM, MD, Baltimore, Md.
Nasal transepithelial potential difference (PD) has been shown to vary with mucosal morphology (Knowles; Am Rev Respir Dis 1981; 124:484). It is considered a measure of epithelial integrity and may be altered by diseases or drugs that alter active ion flux or by physical disruption of epithelial integrity. Animal toxicology studies have demonstrated that epithelial lesions in the upper airway are nonuniforrnly distributed and that focal abnormalities 'in epithelial morphology may be present. We hypothesized that patients with chronic sinusitis who are post functional endoscopic sinus surgery (post-FESS) would demonstrate focal differences in PD compared with healthy subjects. Nine patients with chronic sinusitis who were 6 months to 3 years post-FESS were compared with 10 normal control subjects. All subjects underwent determination of nasal transepithelial potential difference using an adaptation of the method of Takahashi (Am J Physiol 1993;9:L33-7) using a subdermal reference electrode. Patients with chronic sinusitis who are post-FESS demonstrate significant focal differences in orenasal transepithelial potential difference compared with normal subjects. We speculate that the differences in the potential difference of the posterior palate may reflect mucosal injury in the distribution of the nerves originating in the sphenopalatine ganglion.
kl.I o'J r
r
nucleus (CN) has been used for rehabilitation of profoundly deaf patients who are not suitable for cochlear implants. Most of these patients were implanted with an electrode that was placed on the surface of the cochlear nucleus. Previous animal studies have demonstrated greater efficiency of a penetrating CN electrode in activating the central auditory system than a surface electrode. The objective of this work is to study and characterize the electrically evoked middle latency response (MLR) generated by stimulation through a penetrating multichannel CN electrode. A series of six pigmented guinea pigs were used i n this study. Standards of humane animal care were adhered to throughout the project. Animals were anesthetized and underwent acute implantation of a penetrating multichannel CN electrode through an occipital craniotomy approach. The stimulating electrodes consisted of a silicon substrate that supported an array of thin-film conductors. Each electrode contained five stimulation pads. Threshold, latency, and input-output functions of the electrically evoked MLR using different combinations of stimulation pads were studied. There were no differences in the threshold for eliciting the MLR between different stimulation pads. However, there were systematic differences in the latency and the amplitude of the input-output functions depending on the site of stimulation within the CN. The results support the hypothesis that discrete activation of neuronal subpopulations within the CN is possible with a multichannel penetrating microelectrode. Studies are currently underway using double-label autoradiographic techniques to further characterize the patterns of central auditory system activation using penetrating multichannel CN electrodes. This would enhance the development of prostheses and coding strategies that may provide multiple channels of information to improve patients' benefits from a CN implant. (Supported by a Deafness Research Foundation grant.) Poster 78
Processing Negativity for Semantic Incongruence in Young and Elderly Persons JENNIFER PARKER PORTER, MD (presenter), and JAMES F. JERGER, PHD, Houston, Tex.
The N400 auditory evoked response has been shown to be present during the processing of semantic incongruity. The specific aim of this project was tO compare the N400 auditory evoked response of the geriatric population with that of young persons on a sentence comprehension task in the presence of background speech competition. This study was a prospective, nonrandomized comparison of two groups of subjects: 10 elderly persons between the ages of 70 and 90 years and 10 young adults between the ages of 18 and 29 years. Two conditions were evaluated. The first condition involved sentences presented in the presence of background
Scientific Sessions- - Monday
P 101
speech competition run in the forward direction. In this mode the competition had the potential to produce both peripheral masking and central interference effects. In the second condition the target sentences were mixed with the background speech competition played in a backward mode. The average long-term spectrum remained constant, but there was no semantic distraction. The competition could only produce peripheral masking effects. Right and left ears were tested separately. In young adults the topographic brain map of the N400 response was centered in the region of the Cz and Pz electrodes. Results showed a right-ear advantage in the young population with respect to the reaction time and amp]itude of the N400 response. In the elderly subjects the amplitude of the N400 response and the reaction times were increased and the topographic distribution is altered; hnplications for evaluation of speech understanding in the elderly will be discussed. P o s t e r 79
Focal Differences in Nasal-Oral Potential Differences Between Postoperative Endoscopic Sinus Surgery Patients and Control Patients MICHAEL A. DIAS, MD (presenter), PERRYW. ALEXION, MD, THOMAS K. FITZGERALD,BS, PAUL F. CASTELLANOS, MD, JOHN F. BIEDLINGMAIER, MD, and REBECCA BASCOM, MD, Baltimore, Md.
Nasal transepithelial potential difference (PD) has been shown to vary with mucosal morphology (Knowles; Am Rev Respir Dis 1981; 124:484). It is considered a measure of epithelial integrity and may be altered by diseases or drugs that alter active ion flux or by physical disruption of epithelial integrity. Animal toxicology studies have demonstrated that epithelial lesions in the upper airway are nonuniforrnly distributed and that focal abnormalities 'in epithelial morphology may be present. We hypothesized that patients with chronic sinusitis who are post functional endoscopic sinus surgery (post-FESS) would demonstrate focal differences in PD compared with healthy subjects. Nine patients with chronic sinusitis who were 6 months to 3 years post-FESS were compared with 10 normal control subjects. All subjects underwent determination of nasal transepithelial potential difference using an adaptation of the method of Takahashi (Am J Physiol 1993;9:L33-7) using a subdermal reference electrode. Patients with chronic sinusitis who are post-FESS demonstrate significant focal differences in orenasal transepithelial potential difference compared with normal subjects. We speculate that the differences in the potential difference of the posterior palate may reflect mucosal injury in the distribution of the nerves originating in the sphenopalatine ganglion.
kl.I o'J r
r