1985 — 1991 |
Glendenning, Karen K |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Acoustic Chiasm: Anatomy and Behavior @ Florida State University
Ablation behavior experimentation on the hindbrain auditory system has led to the conclusion that the superior olivary complex (or SOC) in the medulla may serve the auditory system as an "acoustic chiasm". The primary evidence is that unilateral lesions in the auditory pathway anywhere below this structure (that is, in the cochlea, cochlear nucleus, trap]ezoid body) result in sound localization deficits either in both hemifields of auditory space or in the henifield ipsilateral to the lesion. In sharp contrast, unilateral lesions in the pathway anywhere above the SOC (that is, in the lateral lemniscus or beyond) result in sound localization deficits only in the hemifield contralateral to the lesion. Therefore, there is a clear functional parallel between the SOC and the optic chiasm even though there is no obvious anatomical parallel. We propose to study the anatomical basis and functional consequences of this chiasmatic process in a series of tract-tracing and ablation-behavior experiments in cats. Using standard techniques of HRP, HRP-WGA conjugate, fluorescent dye, and tritiated amino-acid autoradiography, we will determine the locations and cell-types originating the afferent supply converging on the binaural nuclei of the SOC and the trajectories and possible collateralization of their axons. We will also determine the distribution, collateralization, and trajectory of the efferents of these nuclei as they ascend to the pontine and midbrain levels. Using rigorous psychophysical techniques for testing sound localization and basic hearing capacities in cats with unilateral lesions in the afferents or efferents of SOC in combination with a cochlear lesion either ipsilateral or contralateral to the CNS lesion, we will study the fractionation of normal hearing capacities as a result of the fractionation of the chiasm in order to express the behavioral consequences of the chiasmatic process both in terms of ears of origin and in terms of hemifields of space. Because the acoustic chiasm is a process that is best defined in ablationn-behavior terms, and because the function of the chiasm obviously depends on its afferent-efferent relationships, we expect both lines of experimentation to aid and guide the other and together, to yield a more coherent understanding of the chiasmatic process than could either line alone.
|
1 |
1993 |
Glendenning, Karen K |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Acoustic Chiasma--Anatomy and Behavior @ Florida State University
Ablation behavior experimentation on the hindbrain auditory system has led to the conclusion that the superior olivary complex (or SOC) in the medulla may serve the auditory system as an "acoustic chiasm". The primary evidence is that unilateral lesions in the auditory pathway anywhere below this structure (that, in the cochlea, cochlear nucleus, trapezoid body) result in sound localization deficits either in both hemifields of auditory space or in the hemifield ipsilateral to the lesion. In sharp contrast, unilateral lesions in the pathway anywhere above the SOC (that is, in the lateral lemniscus or beyond) result in sound localization deficits only in the hemifield contralateral to the lesion. Therefore, there is a clear functional parallel between the SOC and the optic chiasm even though there is no obvious anatomical parallel. We propose to continue studying the anatomical and neurochemical basis and the functional consequences of this chiasm-like process in a series of tract-tracing, 2-DG, transmitter-identification, and ablation-behavior experiments in cats. In the new project period we will focus much of our early effort on the efferent projections of LSO and then on the afferents and efferents of DLL. Because the project entails rigorous psychophysical tests of sound localization capacities before and after selective hindbrain tract- sections or nuclear ablations, we hope the research will contribute to the understanding of auditory dysfunction in humans.
|
1 |
1994 — 1995 |
Glendenning, Karen K |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Acoustic Chiasm--Anatomy and Behavior @ Florida State University
Ablation behavior experimentation on the hindbrain auditory system has led to the conclusion that the superior olivary complex (or SOC) in the medulla may serve the auditory system as an "acoustic chiasm". The primary evidence is that unilateral lesions in the auditory pathway anywhere below this structure (that, in the cochlea, cochlear nucleus, trapezoid body) result in sound localization deficits either in both hemifields of auditory space or in the hemifield ipsilateral to the lesion. In sharp contrast, unilateral lesions in the pathway anywhere above the SOC (that is, in the lateral lemniscus or beyond) result in sound localization deficits only in the hemifield contralateral to the lesion. Therefore, there is a clear functional parallel between the SOC and the optic chiasm even though there is no obvious anatomical parallel. We propose to continue studying the anatomical and neurochemical basis and the functional consequences of this chiasm-like process in a series of tract-tracing, 2-DG, transmitter-identification, and ablation-behavior experiments in cats. In the new project period we will focus much of our early effort on the efferent projections of LSO and then on the afferents and efferents of DLL. Because the project entails rigorous psychophysical tests of sound localization capacities before and after selective hindbrain tract- sections or nuclear ablations, we hope the research will contribute to the understanding of auditory dysfunction in humans.
|
1 |
1994 — 1996 |
Glendenning, Karen K |
R03Activity Code Description: To provide research support specifically limited in time and amount for studies in categorical program areas. Small grants provide flexibility for initiating studies which are generally for preliminary short-term projects and are non-renewable. |
Behavioral Roles of Auditory Cortex @ Florida State University
Ablation behavior experimentation on the hindbrain auditory system has led to the conclusion that the superior olivary complex (or SOC) in the medulla serves the auditory system as an "acoustic chiasm". The primary evidence is that unilateral lesions in the auditory pathway anywhere below this structure (that is, in the cochlea, cochlear nucleus, trapezoid body) result in sound localization deficits either in both hemifields of auditory space or in the hemifield ipsilateral to the lesion. In sharp contrast, unilateral lesions in the pathway anywhere above the SOC (that is, in the lateral lemniscus or beyond) result in sound localization deficits only in the hemifield contralateral to the lesion. Therefore, there is a clear functional parallel between the SOC and the optic chiasm even though there is no obvious anatomical parallel. The neuroanatomical and neurochemical substrate and the behavioral consequences of this chiasmatic process are the focus of the parent grant. The present FIRCA proposal will extend the parent grant's anatomical focus to the auditory forebrain, in particular to auditory cortex. In addition, it will extend the parent grant's behavioral focus (on azimuth discrimination mechanisms) to include moving sound-sources and possibly, more fundamental capacities of hearing (i.e., time-by-azimuth, frequency or intensity discriminations). Because the project entails rigorous psychophysical tests of hearing capacities before and after selective cortical ablations, the research should contribute to the understanding of auditory dysfunction in humans resulting from stroke or cortical injury.
|
1 |
1994 |
Glendenning, Karen K |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Behavioral Roles of Dorsal Cochlear Nucleus @ Florida State University |
1 |
1997 — 1999 |
Glendenning, Karen K |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Sensory Cortex @ Florida State University
DESCRIPTION: The long term objective of the proposed research is to discover the changing behavioral roles which parallel the evolution of sensory, association, and motor cortex in the historical lineage leading to Primates and Man. The general strategy begins with a description of the structure-function relationships of major areas of neocortex in a number of neurologically generalized mammals specifically selected for their sequential common ancestry with Primates. The methods have included cytoarchitectonic and anatomical tract-tracing techniques to determine the successive changes in the location, extent, and connections of sensory and motor areas and then receptor-binding and immunohistochemical techniques for neurotransmitter-identification of the afferents and efferents for the same areas. The results of these structural studies are then used to guide comparative behavioral studies and ablation-behavior experiments to determine the history of the behavioral contributions of the several areas. In this manner the evolutionary development of the neocortex is traced from its most primitive mammalian form to the Primate form in an attempt to understand the contributions of its many parts. In this application they focus on the behavioral consequences of the three most radical evolutionary changes in form which have been already uncovered.
|
1 |