Biomaterial Database

Topography of intensity tuning in cat primary auditory cortex: single-neuron versus multiple-neuron recordings. 1995

M L Sutter, and C E Schreiner

Coleman Memorial Laboratory, Department of Otolaryngology, W. M. Keck Center for Integrative Neuroscience, University of California, San Francisco 94143-0732.

1. We studied the spatial distributions of amplitude tuning (monotonicity of rate-level functions) and response threshold of single neurons along the dorsoventral extent of cat primary auditory cortex (AI). To pool data across animals, we used the multiple-unit map of monotonicity as a frame of reference. Amplitude selectivity of multiple units is known to vary systematically along isofrequency contours, which run roughly in the dorsoventral direction. Clusters sharply tuned for intensity (i.e., "nonmonotonic" clusters) are located near the center of the contour. A second nonmonotonic region can be found several millimeters dorsal to the center. We used the locations of these two nonmonotonic regions as reference points to normalize data across animals. Additionally, to compare this study to sharpness of frequency tuning results, we also used multiple-unit bandwidth (BW) maps as references to pool data. 2. The multiple-unit amplitude-related topographies recorded in previous studies were confirmed. Pooled multiple-unit maps closely approximated the previously reported individual case maps when the multiple-unit monotonicity or the map of bandwidth (in octaves) of pure tones to which a cell responds 40 dB above minimum threshold were used as the pooling reference. When the map of bandwidth (in octaves) of pure tones to which a cell responds 10 dB above minimum threshold map was used as part of the measure, the pooled spatial pattern of multiple-unit activity was degraded. 3. Single neurons exhibited nonmonotonic rate-level functions more frequently than multiple units. Although common in single-neuron recordings (28%), strongly nonmonotonic recordings (firing rates reduced by > 50% at high intensities) were uncommon (8%) in multiple-unit recordings. Intermediately nonmonotonic neurons (firing rates reduced between 20% and 50% at high intensities) occurred with nearly equal probability in single-neuron (28%) and multiple-unit (26%) recordings. The remaining recordings for multiple units (66%) and single units (44%) were monotonic (firing rates within 20% of the maximum at the highest tested intensity). 4. In ventral AI (AIv), the topography of monotonicity for single units was qualitatively similar to multiple units, although single units were on average more intensity selective. In dorsal AI (AId) we consistently found a spatial gradient for sharpness of intensity tuning for multiple units; however, for pooled single units in Aid there was no clear topographic gradient. 5. Response (intensity) thresholds of single neurons were not uniformly distributed across the dorsoventral extent of AI.(ABSTRACT TRUNCATED AT 400 WORDS)

UI	MeSH Term	Description	Entries
D009474	Neurons	The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.	Nerve Cells,Cell, Nerve,Cells, Nerve,Nerve Cell,Neuron
D002415	Cats	The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)	Felis catus,Felis domesticus,Domestic Cats,Felis domestica,Felis sylvestris catus,Cat,Cat, Domestic,Cats, Domestic,Domestic Cat
D004594	Electrophysiology	The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.
D000200	Action Potentials	Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.	Spike Potentials,Nerve Impulses,Action Potential,Impulse, Nerve,Impulses, Nerve,Nerve Impulse,Potential, Action,Potential, Spike,Potentials, Action,Potentials, Spike,Spike Potential
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001303	Auditory Cortex	The region of the cerebral cortex that receives the auditory radiation from the MEDIAL GENICULATE BODY.	Brodmann Area 41,Brodmann Area 42,Brodmann's Area 41,Heschl Gyrus,Heschl's Gyrus,Auditory Area,Heschl's Convolutions,Heschl's Gyri,Primary Auditory Cortex,Temporal Auditory Area,Transverse Temporal Gyri,Area 41, Brodmann,Area 41, Brodmann's,Area 42, Brodmann,Area, Auditory,Area, Temporal Auditory,Auditory Areas,Auditory Cortex, Primary,Brodmanns Area 41,Cortex, Auditory,Cortex, Primary Auditory,Gyrus, Heschl,Gyrus, Heschl's,Gyrus, Transverse Temporal,Heschl Convolutions,Heschl Gyri,Heschls Convolutions,Heschls Gyri,Heschls Gyrus,Primary Auditory Cortices,Temporal Auditory Areas,Temporal Gyrus, Transverse,Transverse Temporal Gyrus
D001309	Auditory Threshold	The audibility limit of discriminating sound intensity and pitch.	Auditory Thresholds,Threshold, Auditory,Thresholds, Auditory