Functional laminar and columnar organization of the auditory centers in echolocating Japanese greater horseshoe bats

Taniguchi, Ikuo; Arai, Okio; Saito, Nozomu

doi:10.1016/0304-3940(88)90308-4

Cited by 5 publications

(1 citation statement)

References 9 publications

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“…In the DSCF area, as in the CF/CF and FM-FM areas, neurons with similar physiological properties are arranged in columns (Taniguchi et al 1988). There is also an anatomic basis of this columnar organization in terms of thalamocortical projections and corticocortical connectivity so that small, localized injections of horseradish peroxidase in one auditory cortical area label discrete columns in other auditory cortical areas (Fitzpatrick et al 1998).…”

Section: Spatial Organization Of Response Parametersmentioning

confidence: 99%

Facilitatory and Inhibitory Frequency Tuning of Combination-Sensitive Neurons in the Primary Auditory Cortex of Mustached Bats

Kanwal

Fitzpatrick

Suga

1999

Journal of Neurophysiology

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Mustached bats, Pteronotus parnellii parnellii, emit echolocation pulses that consist of four harmonics with a fundamental consisting of a constant frequency (CF(1-4)) component followed by a short, frequency-modulated (FM(1-4)) component. During flight, the pulse fundamental frequency is systematically lowered by an amount proportional to the velocity of the bat relative to the background so that the Doppler-shifted echo CF(2) is maintained within a narrowband centered at approximately 61 kHz. In the primary auditory cortex, there is an expanded representation of 60.6- to 63. 0-kHz frequencies in the "Doppler-shifted CF processing" (DSCF) area where neurons show sharp, level-tolerant frequency tuning. More than 80% of DSCF neurons are facilitated by specific frequency combinations of approximately 25 kHz (BF(low)) and approximately 61 kHz (BF(high)). To examine the role of these neurons for fine frequency discrimination during echolocation, we measured the basic response parameters for facilitation to synthesized echolocation signals varied in frequency, intensity, and in their temporal structure. Excitatory response areas were determined by presenting single CF tones, facilitative curves were obtained by presenting paired CF tones. All neurons showing facilitation exhibit at least two facilitative response areas, one of broad spectral tuning to frequencies centered at BF(low) corresponding to a frequency in the lower half of the echolocation pulse FM(1) sweep and another of sharp tuning to frequencies centered at BF(high) corresponding to the CF(2) in the echo. Facilitative response areas for BF(high) are broadened by approximately 0.38 kHz at both the best amplitude and 50 dB above threshold response and show lower thresholds compared with the single-tone excitatory BF(high) response areas. An increase in the sensitivity of DSCF neurons would lead to target detection from farther away and/or for smaller targets than previously estimated on the basis of single-tone responses to BF(high). About 15% of DSCF neurons show oblique excitatory and facilitatory response areas at BF(high) so that the center frequency of the frequency-response function at any amplitude decreases with increasing stimulus amplitudes. DSCF neurons also have inhibitory response areas that either skirt or overlap both the excitatory and facilitatory response areas for BF(high) and sometimes for BF(low). Inhibition by a broad range of frequencies contributes to the observed sharpness of frequency tuning in these neurons. Recordings from orthogonal penetrations show that the best frequencies for facilitation as well as excitation do not change within a cortical column. There does not appear to be any systematic representation of facilitation ratios across the cortical surface of the DSCF area.

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Section: Spatial Organization Of Response Parametersmentioning

confidence: 99%

Facilitatory and Inhibitory Frequency Tuning of Combination-Sensitive Neurons in the Primary Auditory Cortex of Mustached Bats

Kanwal

Fitzpatrick

Suga

1999

Journal of Neurophysiology

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Frequency and space representation in the primary auditory cortex of the frequency modulating batEptesicus fuscus

1989

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1. Frequency and space representation in the auditory cortex of the big brown bat, Eptesicus fuscus, were studied by recording responses of 223 neurons to acoustic stimuli presented in the bat's frontal auditory space. 2. The majority of the auditory cortical neurons were recorded at a depth of less than 500 microns with a response latency between 8 and 20 ms. They generally discharged phasically and had nonmonotonic intensity-rate functions. The minimum threshold, (MT) of these neurons was between 8 and 82 dB sound pressure level (SPL). Half of the cortical neurons showed spontaneous activity. All 55 threshold curves are V-shaped and can be described as broad, intermediate, or narrow. 3. Auditory cortical neurons are tonotopically organized along the anteroposterior axis of the auditory cortex. High-frequency-sensitive neurons are located anteriorly and low-frequency-sensitive neurons posteriorly. An overwhelming majority of neurons were sensitive to a frequency range between 30 and 75 kHz. 4. When a sound was delivered from the response center of a neuron on the bat's frontal auditory space, the neuron had its lowest MT. When the stimulus amplitude was increased above the MT, the neuron responded to sound delivered within a defined spatial area. The response center was not always at the geometric center of the spatial response area. The latter also expanded with stimulus amplitude. High-frequency-sensitive neurons tended to have smaller spatial response areas than low-frequency-sensitive neurons. 5. Response centers of all 223 neurons were located between 0 degrees and 50 degrees in azimuth, 2 degrees up and 25 degrees down in elevation of the contralateral frontal auditory space. Response centers of auditory cortical neurons tended to move toward the midline and slightly downward with increasing best frequency. 6. Auditory space representation appears to be systematically arranged according to the tonotopic axis of the auditory cortex. Thus, the lateral space is represented posteriorly and the middle space anteriorly. Space representation, however, is less systematic in the vertical direction. 7. Auditory cortical neurons are columnarly organized. Thus, the BFs, MTs, threshold curves, azimuthal location of response centers, and auditory spatial response areas of neurons sequentially isolated from an orthogonal electrode penetration are similar.

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Brain activity patterns in flying, echolocating bats (Pteronotus parnellii): Assessment by high resolution autoradiographic imaging with [3H]2-deoxyglucose

Duncan

Henson

1994

Neuroscience

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Functional laminar and columnar organization of the auditory centers in echolocating Japanese greater horseshoe bats

Cited by 5 publications

References 9 publications

Facilitatory and Inhibitory Frequency Tuning of Combination-Sensitive Neurons in the Primary Auditory Cortex of Mustached Bats

Facilitatory and Inhibitory Frequency Tuning of Combination-Sensitive Neurons in the Primary Auditory Cortex of Mustached Bats

Frequency and space representation in the primary auditory cortex of the frequency modulating batEptesicus fuscus

Brain activity patterns in flying, echolocating bats (Pteronotus parnellii): Assessment by high resolution autoradiographic imaging with [3H]2-deoxyglucose

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