The primary auditory cortex (AI) of mammals shows several superimposed functional organizations when explored with simple signals such as pure tones. Basic spatial organizations have been described now for stimulus frequency, bandwidth, spectral envelope, frequency modulation, latency, response threshold, and binaural interaction. The consequences of these organizations for the cortical representation of complex signals, in particular elemental speech signals, is of special interest since similar principles may provide the basis for the perception and categorization of speech in humans. The representational principles will be explored with elemental speech signals in AI of speech squirrel in AI of squirrel (Saimiri sciureus) naive to the sounds and animals that have acquired behavioral affinity to the signals. The behavioral relevance of the studied complex signals will be established by engaging the animals in a psychophysical task of signal discrimination and generalized classification. The task will be performed under varying stimulus and environmental conditions such as by using different stimulus intensities, fundamental frequencies, and to utilize generalized classification schemes that operate independent from signal level and background conditions, thus approaching human discrimination and classification abilities. Determining the cortical encoding of elemental speech sounds on conjunction with reverse-correlation analysis of spectro-temporal receptive fields in naive and highly trained animals will illuminate basic attributes of complex signal representations as well the refinement of coding attributes with learning to discriminate and classify the signals. Recording of cortical activity from animals while they are being trained to discriminate speech sounds will let us follow the time course of plastic changes and establish physiological correlates of perceptual discrimination and detection thresholds. The emergence of refined spatial-temporal patterns of cortical activity by learning-induced plasticity and their relationship to perceptual capacities of the animals provides a basic cellular model of speech sound representation.

Project Start
2002-05-01
Project End
2007-04-30
Budget Start
2002-05-01
Budget End
2003-04-30
Support Year
6
Fiscal Year
2002
Total Cost
$173,795
Indirect Cost
Name
University of California San Francisco
Department
Type
DUNS #
073133571
City
San Francisco
State
CA
Country
United States
Zip Code
94143
Zhou, Xiaoming; Merzenich, Michael M (2012) Environmental noise exposure degrades normal listening processes. Nat Commun 3:843
Nagel, Katherine; Kim, Gunsoo; McLendon, Helen et al. (2011) A bird brain's view of auditory processing and perception. Hear Res 273:123-33
Zhou, Xiaoming; Merzenich, Michael M (2009) Developmentally degraded cortical temporal processing restored by training. Nat Neurosci 12:26-8
Heuer, Hilary W; Tokiyama, Stefanie; Lisberger, Stephen G (2008) Doing without learning: stimulation of the frontal eye fields and floccular complex does not instruct motor learning in smooth pursuit eye movements. J Neurophysiol 100:1320-31
de Villers-Sidani, Etienne; Simpson, Kimberly L; Lu, Y-F et al. (2008) Manipulating critical period closure across different sectors of the primary auditory cortex. Nat Neurosci 11:957-65
Nagel, Katherine I; Doupe, Allison J (2008) Organizing principles of spectro-temporal encoding in the avian primary auditory area field L. Neuron 58:938-55
Schoppik, David; Nagel, Katherine I; Lisberger, Stephen G (2008) Cortical mechanisms of smooth eye movements revealed by dynamic covariations of neural and behavioral responses. Neuron 58:248-60
Kojima, Satoshi; Doupe, Allison J (2008) Neural encoding of auditory temporal context in a songbird basal ganglia nucleus, and its independence of birds'song experience. Eur J Neurosci 27:1231-44
Liu, Robert C; Schreiner, Christoph E (2007) Auditory cortical detection and discrimination correlates with communicative significance. PLoS Biol 5:e173
Kenet, T; Froemke, R C; Schreiner, C E et al. (2007) Perinatal exposure to a noncoplanar polychlorinated biphenyl alters tonotopy, receptive fields, and plasticity in rat primary auditory cortex. Proc Natl Acad Sci U S A 104:7646-51

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