Speech sounds are the most important sounds that humans hear, yet little is known about the functional properties of the interconnected auditory and auditory-related brain regions that are essential to normal speech perception. Our research goal is to understand where and how speech information is processed within this network. We use novel combinations of complementary invasive and non-invasive experimental methods to study these brain regions in neurosurgery patients who require placement of chronic intracranial electrodes. These experiments involve combining direct cortical electrophysiological recordings with electrical stimulation techniques and anatomical and functional MRI methods. Our investigative strategy makes use of these unique experimental opportunities to overcome long-standing barriers to progress in this research field. Recent methodological advances now enable us to simultaneously study neural processing and connectivity at all levels of this network and directly test neural models of speech perception in human subjects. We will pursue our goals by testing hypotheses regarding: (1) the locations and functional properties of auditory cortical fields and auditory-related cortices of the temporal and frontal lobes, (2) the functional connections between these areas and other regions of the human brain, and (3) the directional flow of speech information within this network. These objectives are pursued by an experienced multidisciplinary group of investigators with expertise encompassing all required clinical and research topic areas. To our knowledge, the resulting data will be the first of its kind to directl demonstrate how speech information is processed at all levels of the temporal-frontal lobe auditory cortical system, and to directly demonstrate point-to-point functional connections between these cortical network regions and sites elsewhere in the human brain. Knowledge of the normal network will improve our understanding of the pathophysiology of disease states affecting this system, and will provide mechanistic insights that are required to inform the design of new treatment strategies.
This research program generates unique information about the functional organization of the human auditory and auditory-related cortex that cannot be obtained using alternative, non-invasive approaches. Knowledge gained from these studies will provide new insights into how speech information is represented within the human brain and aid in the rational design of new therapeutic and rehabilitation strategies for patients affected by a wide range of communication disorders.
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