Erratum and Addendum: Representation of Binaural Stimuli by Single Units in Primary Auditory Cortex of Unanesthesized Cats [J. Acoust. Soc. Amer. 43, 456–461 (1968)]

1968 ◽  
Vol 44 (6) ◽  
pp. 1747-1747
Author(s):  
Joseph L. Hall ◽  
Moise H. Goldstein
Keyword(s):  
Auditory Cortex ◽  
Primary Auditory Cortex ◽  
Single Units

scholarly journals Population Responses Represent Vocalization Identity, Intensity, and Signal-to-Noise Ratio in Primary Auditory Cortex

2019 ◽  
Author(s):  
Ruiye Ni ◽  
David A. Bender ◽  
Dennis L. Barbour
Keyword(s):  
Auditory Cortex ◽  
Single Unit ◽  
Temporal Dynamics ◽  
Population Analysis ◽  
Primary Auditory Cortex ◽  
Population Coding ◽  
Single Units ◽  
Neural Population ◽  
Population Responses ◽  
Noise Ratio

AbstractThe ability to process speech signals under challenging listening environments is critical for speech perception. Great efforts have been made to reveal the underlying single unit encoding mechanism. However, big variability is usually discovered in single-unit responses, and the population coding mechanism is yet to be revealed. In this study, we are aimed to study how a population of neurons encodes behaviorally relevant signals subjective to change in intensity and signal-noise-ratio (SNR). We recorded single-unit activity from the primary auditory cortex of awake common marmoset monkeys (Callithrix jacchus) while delivering conspecific vocalizations degraded by two different background noises: broadband white noise (WGN) and vocalization babble (Babble). By pooling all single units together, the pseudo-population analysis showed the population neural responses track intra- and inter-trajectory angle evolutions track vocalization identity and intensity/SNR, respectively. The ability of the trajectory to track the vocalizations attribute was degraded to a different degree by different noises. Discrimination of neural populations evaluated by neural response classifiers revealed that a finer optimal temporal resolution and longer time scale of temporal dynamics were needed for vocalizations in noise than vocalizations at multiple different intensities. The ability of population responses to discriminate between different vocalizations were mostly retained above the detection threshold.Significance StatementHow our brain excels in the challenge of precise acoustic signal encoding against noisy environment is of great interest for scientists. Relatively few studies have strived to tackle this mystery from the perspective of neural population responses. Population analysis reveals the underlying neural encoding mechanism of complex acoustic stimuli based upon a pool of single units via vector coding. We suggest the spatial population response vectors as one important way for neurons to integrate multiple attributes of natural acoustic signals, specifically, marmots’ vocalizations.

Synchrony between single-unit activity and local field potentials in relation to periodicity coding in primary auditory cortex

1995 ◽  
Vol 73 (1) ◽  
pp. 227-245 ◽  
Author(s):  
J. J. Eggermont ◽  
G. M. Smith
Keyword(s):  
Auditory Cortex ◽  
Local Field ◽  
Single Unit ◽  
Transfer Functions ◽  
Local Field Potentials ◽  
Primary Auditory Cortex ◽  
Single Units ◽  
Field Potentials ◽  
Level Crossings ◽  
Low Pass

1. We recorded responses from 136 single units and the corresponding local field potentials (LFPs) from the same electrode at 44 positions in the primary auditory cortex of 25 juvenile, ketamine-anesthetized cats in response to periodic click trains with click repetition rates between 1 and 32 Hz; to Poisson-distributed click trains with an average click rate of 4 Hz; and under spontaneous conditions. The aim of the study is to evaluate the synchrony between LFPs and single-unit responses, to compare their coding of periodic stimuli, and to elucidate mechanisms that limit this periodicity coding in primary auditory cortex. 2. We obtained averaged LFPs either as click-triggered averages, the classical evoked potentials, or as spike-triggered averages. We quantified LFPs by initial negative peak-to-positive peak amplitude. In addition, we obtained trigger events from negativegoing level crossings (at approximately 2 SD below the mean) of the 100-Hz low-pass electrode signal. We analyzed these LFP triggers similarly to single-unit spikes. 3. The average ratio of the LFP amplitude in response to the second click in a train and the LFP amplitude to the first click as a function of click rate was low-pass with a slight resonance at approximately 10 Hz, and, above that frequency, decreasing with a slope of approximately 24 dB/octave. We found the 50% point at approximately 16 Hz. In contrast, the LFP amplitude averaged over entire click trains was low-pass with a similar resonance but a high-frequency slope of 12 dB/octave and a 50% point at approximately 12 Hz. 4. The LFP amplitude for click repetition rates between 5 and 11 Hz often showed augmentation, i.e., the amplitude increased in response to the first few clicks in the train and thereafter decreased. This augmentation was paralleled by an increase in the probability of firing in single units simultaneously recorded on the same electrode. 5. We calculated temporal modulation transfer functions (tMTFs) for single-unit spikes and for LFP triggers. They were typically bandpass with a best modulating frequency of 10 Hz and similar shape for both single-unit spikes and LFP triggers. The tMTF per click, obtained by dividing the tMTF by the number of clicks in the train, was low-pass with a 50% cutoff frequency at approximately Hz, similar to that for the average LFP amplitude. 6. the close similarity of the tMTFs for single-unit spikes and LFP triggers suggests that single-unit tMTFs can be predicted from LFP level crossings.(ABSTRACT TRUNCATED AT 400 WORDS)

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