Response characteristics of primary auditory cortex neurons underlying perceptual asymmetry of ramped and damped sounds

The mouse is a promising model system for auditory cortex research because of the powerful genetic tools available for manipulating its neural circuitry. Previous studies have identified two tonotopic auditory areas in the mouse—primary auditory cortex (AI) and anterior auditory field (AAF)— but auditory receptive fields in these areas have not yet been described. To establish a foundation for investigating auditory cortical circuitry and plasticity in the mouse, we characterized receptive-field structure in AI and AAF of anesthetized mice using spectrally complex and temporally dynamic stimuli as well as simple tonal stimuli. Spectrotemporal receptive fields (STRFs) were derived from extracellularly recorded responses to complex stimuli, and frequency-intensity tuning curves were constructed from responses to simple tonal stimuli. Both analyses revealed temporal differences between AI and AAF responses: peak latencies and receptive-field durations for STRFs and first-spike latencies for responses to tone bursts were significantly longer in AI than in AAF. Spectral properties of AI and AAF receptive fields were more similar, although STRF bandwidths were slightly broader in AI than in AAF. Finally, in both AI and AAF, a substantial minority of STRFs were spectrotemporally inseparable. The spectrotemporal interaction typically appeared in the form of clearly disjoint excitatory and inhibitory subfields or an obvious spectrotemporal slant in the STRF. These data provide the first detailed description of auditory receptive fields in the mouse and suggest that although neurons in areas AI and AAF share many response characteristics, area AAF may be specialized for faster temporal processing.

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Ripple Analysis in Ferret Primary Auditory Cortex. 1. Response Characteristics of Single Units to Sinusoidally Rippled Spectra

10.21236/ada452778 ◽

1994 ◽

Cited By ~ 4

Author(s):

S. A. Shamma ◽

H. Versnel ◽

N. Kowalski

Keyword(s):

Auditory Cortex ◽

Primary Auditory Cortex ◽

Single Units ◽

Response Characteristics ◽

Rippled Spectra

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Effects of neonatal partial deafness and chronic intracochlear electrical stimulation on auditory and electrical response characteristics in primary auditory cortex

Hearing Research ◽

10.1016/j.heares.2009.08.006 ◽

2009 ◽

Vol 257 (1-2) ◽

pp. 93-105 ◽

Cited By ~ 10

Author(s):

James B. Fallon ◽

Robert K. Shepherd ◽

Mel Brown ◽

Dexter R.F. Irvine

Keyword(s):

Electrical Stimulation ◽

Auditory Cortex ◽

Electrical Response ◽

Primary Auditory Cortex ◽

Response Characteristics

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Binaural organization of primary auditory cortex in the ferret (Mustela putorius)

Journal of Neurophysiology ◽

10.1152/jn.1994.71.3.904 ◽

1994 ◽

Vol 71 (3) ◽

pp. 904-913 ◽

Cited By ~ 47

Author(s):

J. B. Kelly ◽

P. W. Judge

Keyword(s):

Auditory Cortex ◽

Primary Auditory Cortex ◽

Intensity Difference ◽

Sound System ◽

Response Properties ◽

Response Characteristics ◽

Binaural Stimulation ◽

Binaural Summation ◽

Mapping Techniques ◽

Evoked Activity

1. The distribution of binaural responses within the ferret's primary auditory cortex was determined by standard microelectrode mapping techniques. Single and multiple unit responses were recorded from the middle ectosylvian gyrus of barbiturate-anesthetized animals with tungsten microelectrodes (1.2-1.8 M omega) inserted into the brain perpendicular to the cortical surface. The characteristic frequency (CF) and binaural response characteristics were determined for each point sampled. 2. Gated pure tones were delivered independently to the two ears through a sealed sound system, and binaural response types were determined by comparison of evoked activity for monaural and binaural stimulation. Most binaural responses fell into one of three major groups: binaural summation (EE/F), binaural suppression (EO/I), or mixed binaural summation and suppression. 3. The neurons tended to be grouped together on the basis of their binaural response properties. Zones of binaural summation and suppression extended across the surface of the middle ectosylvian gyrus and intersected with regions of sound frequency representation. 4. Particular attention was paid to the distribution of binaural responses within isofrequency contours in the ferret's primary auditory cortex (AI). Along the length of each isofrequency contour, areas of EE/F alternated with areas of EO/I. The summation areas were typically between 0.5 and 0.7 mm wide. Single neurons with mixed binaural response properties were frequently found between groups of EE/F and EO/I cells. The mixed responses appeared to mark a transition in location between zones of summation and suppression responses. 5. The distribution of interaural intensity difference (IID) thresholds was also examined along the length of isofrequency contours. No systematic relation was found between IID threshold and the distance along an isofrequency contour.

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Sex-dependent hemispheric asymmetries for processing frequency-modulated sounds in the primary auditory cortex of the mustached bat

Journal of Neurophysiology ◽

10.1152/jn.00952.2011 ◽

2012 ◽

Vol 108 (6) ◽

pp. 1548-1566 ◽

Cited By ~ 12

Author(s):

Stuart D. Washington ◽

Jagmeet S. Kanwal

Keyword(s):

Auditory Cortex ◽

Primary Auditory Cortex ◽

Tone Burst ◽

Hemispheric Differences ◽

Constant Frequency ◽

Response Latencies ◽

Peak Response ◽

Response Characteristics ◽

Species Specific ◽

The Right

Species-specific vocalizations of mammals, including humans, contain slow and fast frequency modulations (FMs) as well as tone and noise bursts. In this study, we established sex-specific hemispheric differences in the tonal and FM response characteristics of neurons in the Doppler-shifted constant-frequency processing area in the mustached bat's primary auditory cortex (A1). We recorded single-unit cortical activity from the right and left A1 in awake bats in response to the presentation of tone bursts and linear FM sweeps that are contained within their echolocation and/or communication sounds. Peak response latencies to neurons' preferred or best FMs were significantly longer on the right compared with the left in both sexes, and in males this right-left difference was also present for the most excitatory tone burst. Based on peak response magnitudes, right hemispheric A1 neurons in males preferred low-rate, narrowband FMs, whereas those on the left were less selective, responding to FMs with a variety of rates and bandwidths. The distributions of parameters for best FMs in females were similar on the two sides. Together, our data provide the first strong physiological support of a sex-specific, spectrotemporal hemispheric asymmetry for the representation of tones and FMs in a nonhuman mammal. Specifically, our results demonstrate a left hemispheric bias in males for the representation of a diverse array of FMs differing in rate and bandwidth. We propose that these asymmetries underlie lateralized processing of communication sounds and are common to species as divergent as bats and humans.

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