Large-scale single-neuron speech sound encoding across the depth of human cortex
Matthew K Leonard1,2, Laura Gwilliams1,2, Kristin K Sellers1,2
1Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA, USA.
Nature
|December 13, 2023
Summary
Researchers explored how the human brain processes speech by recording from individual neurons in the superior temporal gyrus. They found neurons across cortical layers encode diverse speech features, revealing insights into neural speech processing.
Area of Science:
- Neuroscience
- Auditory Neuroscience
- Speech Perception
Background:
- Understanding speech perception necessitates examining neural activity at both the single-neuron and cortical organization levels.
- The superior temporal gyrus is a critical region for processing complex auditory information, including speech.
Purpose of the Study:
- To investigate how individual neurons across cortical layers in the human superior temporal gyrus encode speech information.
- To determine the relationship between single-neuron activity and macroelectrode recordings (electrocorticography) during speech perception.
Main Methods:
- Utilized high-density Neuropixels arrays to record neural activity from 685 neurons across cortical layers at nine sites in the superior temporal gyrus.
- Participants listened to spoken sentences during neural recordings.
- Analyzed single-neuron tuning properties and their spatial organization across cortical depth.
Main Results:
- Single neurons demonstrated encoding of various speech sound cues, including phonetic features, vocal pitch, and temporal dynamics.
- Neurons exhibited heterogeneous selectivity, with dominant tuning to specific features alongside encoding of others.
- Neuronal activity across cortical layers predicted high-frequency field potentials, suggesting a neuronal basis for electrocorticography signals.
Conclusions:
- Single-neuron tuning across cortical laminae is a significant factor in speech encoding within the human superior temporal gyrus.
- This study provides a micro-level understanding of speech processing, linking neuronal activity to macro-scale brain recordings.
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