Differential Distribution of Burst and Single-Spike Responses in Auditory Thalamus

2002 ◽  
Vol 88 (4) ◽  
pp. 2152-2156 ◽  
Author(s):  
Jufang He ◽  
Bin Hu
Keyword(s):  
Medial Geniculate Body ◽  
Primary Auditory Cortex ◽  
Noise Burst ◽  
Auditory Information ◽  
Differential Distribution ◽  
Firing Patterns ◽  
Auditory Thalamus ◽  
Single Spike ◽  
Medial Geniculate ◽  
Low Threshold

The medial geniculate body (MGB) of the auditory thalamus comprises lemniscal and nonlemniscal neurons that project to the primary auditory cortex and limbic structures, respectively. Here we show that in anesthetized guinea pigs, MGB responses to a noise-burst stimulus exhibit distinct and synaptic pathway-specific firing patterns. The majority of nonlemniscal MGB cells exhibited bursting responses, whereas lemniscal neurons discharged mainly single or spike doublets. The burst firing is delayed in nonlemniscal neurons and exhibited several features that are characteristics of those mediated by low-threshold Ca2+ spikes. Such a synaptic pathway-specific allocation of bursting and single-spike firing patterns is consistent with the notion of parallel processing of auditory information in thalamocortical system.

scholarly journals Thalamocortical Projectional Divergence Leads to Complexity in Functional Organizations in Mouse Auditory Cortex

2017 ◽  
Author(s):  
Shinpei Ohga ◽  
Hiroaki Tsukano ◽  
Masao Horie ◽  
Hiroki Terashima ◽  
Nana Nishio ◽  
...  
Keyword(s):  
Auditory Cortex ◽  
Functional Organization ◽  
Medial Geniculate Body ◽  
Primary Auditory Cortex ◽  
Higher Order ◽  
Auditory Information ◽  
Complex Behaviour ◽  
Thalamocortical Projections ◽  
Medial Geniculate ◽  
Auditory Field

AbstractFrequency-related topological projections from the ventral division of the medial geniculate body (MGv) relay the tonotopic organization found in primary auditory cortex (A1). However, relaying circuits of the functional organization to higher-order, secondary auditory field (A2) have not been identified so far. Here, using tracing, we found that A2 receives dense topological projections from MGv in mice, and that tonotopy was established in A2 even when primary fields including A1 were removed. These indicate that thalamic inputs to A2 are sufficient for generating its tonotopy. Moreover, neuronal responses in the thalamocortical recipient layer of A2 showed wider bandwidth and greater heterogeneity of the best frequency distribution than those of A1, which was attributed to larger divergence of thalamocortical projections from MGv to A2 than those from MGv to A1. The current study identifies that the functional organization in the auditory cortex can be determined by the structure of thalamocortical input.Significant StatementAlthough peripheral input patterns to the primary auditory cortex (A1) of the brain are well understood, how tonal information is relayed to higher-order regions such as the secondary auditory field (A2) remains unclear. This work revealed a new source of auditory information to A2; the tonal map in mouse A2 is primarily produced by orderly projections from the primary auditory thalamus. We also found that the complex behaviour and organization of neurons in A2 is generated by divergent projections from the primary thalamus that converge on neurons in A2. Our findings indicate that thalamocortical projections constitute a major factor that determines the regional properties and functional organization of mouse A2.

scholarly journals Distinct Manifestations of Cooperative, Multidimensional Stimulus Representations in Different Auditory Forebrain Stations

2020 ◽  
Vol 30 (5) ◽  
pp. 3130-3147
Author(s):  
Jonathan Y Shih ◽  
Kexin Yuan ◽  
Craig A Atencio ◽  
Christoph E Schreiner
Keyword(s):  
Receptive Fields ◽  
Medial Geniculate Body ◽  
Primary Auditory Cortex ◽  
Linear Filter ◽  
Auditory Information ◽  
Stimulus Response ◽  
Spectral Integration ◽  
Medial Geniculate ◽  
A1 Neurons ◽  
Stimulus Features

Abstract Classic spectrotemporal receptive fields (STRFs) for auditory neurons are usually expressed as a single linear filter representing a single encoded stimulus feature. Multifilter STRF models represent the stimulus-response relationship of primary auditory cortex (A1) neurons more accurately because they can capture multiple stimulus features. To determine whether multifilter processing is unique to A1, we compared the utility of single-filter versus multifilter STRF models in the medial geniculate body (MGB), anterior auditory field (AAF), and A1 of ketamine-anesthetized cats. We estimated STRFs using both spike-triggered average (STA) and maximally informative dimension (MID) methods. Comparison of basic filter properties of first maximally informative dimension (MID1) and second maximally informative dimension (MID2) in the 3 stations revealed broader spectral integration of MID2s in MGBv and A1 as opposed to AAF. MID2 peak latency was substantially longer than for STAs and MID1s in all 3 stations. The 2-filter MID model captured more information and yielded better predictions in many neurons from all 3 areas but disproportionately more so in AAF and A1 compared with MGBv. Significantly, information-enhancing cooperation between the 2 MIDs was largely restricted to A1 neurons. This demonstrates significant differences in how these 3 forebrain stations process auditory information, as expressed in effective and synergistic multifilter processing.

off Responses in the Auditory Thalamus of the Guinea Pig

2002 ◽  
Vol 88 (5) ◽  
pp. 2377-2386 ◽  
Author(s):  
Jufang He
Keyword(s):  
Guinea Pig ◽  
Frequency Tuning ◽  
Medial Geniculate Body ◽  
Noise Burst ◽  
Border Region ◽  
Tuning Curves ◽  
Auditory Thalamus ◽  
Auditory Responses ◽  
Medial Geniculate ◽  
The Mean

on and off auditory responses were examined in the medial geniculate body (MGB) of the guinea pig. Single- and multiunit recordings were carried out on 12 anesthetized animals, and noise-burst or pure-tone stimuli were applied to the ear contralateral to the recording hemisphere. One hundred and thirty-fiveoff or on-off neurons and 160 onneurons were studied, and the tuning curves of 21 on-off oroff neurons were examined from various nuclei of the MGB. The mean minimum threshold of the off responses (40.8 ± 20.0 dB SPL, mean ± SD; range: 0–80 dB SPL) was significantly higher than that of the on responses (28.5 ± 17.6 dB SPL, range: 0–60 dB SPL; n = 17, P < 0.001). Of 10 on-off neurons that showed identifiable tuning frequencies for both on andoff responses, 7 showed a higher off thanon best frequency (BF), 2 showed the same BF for bothon and off, and only 1 showed a slightly loweroff than on BF. Most off responses sampled from the borders of the ventral (MGv) and the rostromedial (MGrm) nuclei of the MGB showed single-peaked tuning curves, similar to those of the on responses in the MGv. The neurons located in the shell (MGs) and dorsal (MGd) nuclei of the MGB showed complicated—either multi-peaked or broad—tuning curves. Alloff responses showed long-duration-selectivity for acoustic stimuli: the mean half-maximum duration was 116.5 ± 114.8 ms ( n = 19, range: 27–411 ms). The latencies of 135off responses were studied in various divisions of the MGB. The ventral border region of MGv showed the shortest latency, followed by the dorsal border region of the MGv, the MGrm, and the caudomedial nucleus (MGcm) of the MGB. The posterior nucleus of the thalamus (Po), the MGd, and the MGs showed much longer mean latencies of >30 ms ( P < 0.05 compared with the border regions of the MGv, ANOVA), with Po showing the greatest mean latency of 60.3 ms and the greatest deviation of 25.5 ms). The latency of the offresponse (29.0 ± 14.0 ms, n = 135) was significantly greater than that of the on response (15.6 ± 9.6 ms, n = 160, P < 0.001). The present results provide valuable information about the threshold, frequency tuning characteristics, minimal response latency, and duration selectivity of off neurons in the auditory thalamus.

scholarly journals Selective Corticofugal Modulation on Sound Processing in Auditory Thalamus of Awake Marmosets

2021 ◽  
Author(s):  
Yuanqing Zhang ◽  
Xiaohui Wang ◽  
Lin Zhu ◽  
Siyi Bai ◽  
Rui Li ◽  
...  
Keyword(s):  
Sensory Processing ◽  
Frequency Tuning ◽  
Signal To Noise Ratio ◽  
Medial Geniculate Body ◽  
Primary Auditory Cortex ◽  
Medial Geniculate ◽  
Auditory Response ◽  
Corticofugal Feedback ◽  
Corticothalamic Feedback

Cortical feedback has long been considered crucial for modulation of sensory processing. In the mammalian auditory system, studies have suggested that corticofugal feedback can have excitatory, inhibitory, or both effects on the response of subcortical neurons, leading to controversies regarding the role of corticothalamic influence. This has been further complicated by studies conducted under different brain states. In the current study, we used cryo-inactivation in the primary auditory cortex (A1) to examine the role of corticothalamic feedback on medial geniculate body (MGB) neurons in awake marmosets. The primary effects of A1 inactivation were a frequency-specific decrease in the auditory response of MGB neurons coupled with an increased spontaneous firing rate, which together resulted in a decrease in the signal-to-noise ratio. In addition, we report for the first-time that A1 robustly modulated the long-lasting sustained response of MGB neurons which changed the frequency tuning after A1 inactivation, e.g., neurons with sharp tuning increased tuning bandwidth whereas those with broad tuning decreased tuning bandwidth. Taken together, our results demonstrate that corticothalamic modulation in awake marmosets serves to enhance sensory processing in a way similar to center-surround models proposed in visual and somatosensory systems, a finding which supports common principles of corticothalamic processing across sensory systems.

scholarly journals Auditory Edge Detection: A Neural Model for Physiological and Psychoacoustical Responses to Amplitude Transients

2001 ◽  
Vol 85 (6) ◽  
pp. 2303-2323 ◽  
Author(s):  
Alon Fishbach ◽  
Israel Nelken ◽  
Yehezkel Yeshurun
Keyword(s):  
Edge Detection ◽  
Auditory System ◽  
Physiological Responses ◽  
Medial Geniculate Body ◽  
Primary Auditory Cortex ◽  
Neural Model ◽  
Perceptual Task ◽  
Edge Detector ◽  
Medial Geniculate ◽  
First Time

Primary segmentation of visual scenes is based on spatiotemporal edges that are presumably detected by neurons throughout the visual system. In contrast, the way in which the auditory system decomposes complex auditory scenes is substantially less clear. There is diverse physiological and psychophysical evidence for the sensitivity of the auditory system to amplitude transients, which can be considered as a partial analogue to visual spatiotemporal edges. However, there is currently no theoretical framework in which these phenomena can be associated or related to the perceptual task of auditory source segregation. We propose a neural model for an auditory temporal edge detector, whose underlying principles are similar to classical visual edge detector models. Our main result is that this model reproduces published physiological responses to amplitude transients collected at multiple levels of the auditory pathways using a variety of experimental procedures. Moreover, the model successfully predicts physiological responses to a new set of amplitude transients, collected in cat primary auditory cortex and medial geniculate body. Additionally, the model reproduces several published psychoacoustical responses to amplitude transients as well as the psychoacoustical data for amplitude edge detection reported here for the first time. These results support the hypothesis that the response of auditory neurons to amplitude transients is the correlate of psychoacoustical edge detection.

scholarly journals Antidromic Activation Reveals Tonotopically Organized Projections From Primary Auditory Cortex to the Central Nucleus of the Inferior Colliculus in Guinea Pig

2007 ◽  
Vol 97 (2) ◽  
pp. 1413-1427 ◽  
Author(s):  
Hubert H. Lim ◽  
David J. Anderson
Keyword(s):  
Auditory Cortex ◽  
Inferior Colliculus ◽  
Spatial Organization ◽  
Medial Geniculate Body ◽  
Primary Auditory Cortex ◽  
Central Nucleus ◽  
Antidromic Activation ◽  
Antidromic Stimulation ◽  
Medial Geniculate ◽  
Layer V

The inferior colliculus (IC) is highly modulated by descending projections from higher auditory and nonauditory centers. Traditionally, corticofugal fibers were believed to project mainly to the extralemniscal IC regions. However, there is some anatomical evidence suggesting that a substantial number of fibers from the primary auditory cortex (A1) project into the IC central nucleus (ICC) and appear to be tonotopically organized. In this study, we used antidromic stimulation combined with other electrophysiological techniques to further investigate the spatial organization of descending fibers from A1 to the ICC in ketamine-anesthetized guinea pigs. Based on our findings, corticofugal fibers originate predominantly from layer V of A1, are amply scattered throughout the ICC and only project to ICC neurons with a similar best frequency (BF). This strict tonotopic pattern suggests that these corticofugal projections are involved with modulating spectral features of sound. Along the isofrequency dimension of the ICC, there appears to be some differences in projection patterns that depend on BF region and possibly isofrequency location within A1 and may be indicative of different descending coding strategies. Furthermore, the success of the antidromic stimulation method in our study demonstrates that it can be used to investigate some of the functional properties associated with corticofugal projections to the ICC as well as to other regions (e.g., medial geniculate body, cochlear nucleus). Such a method can address some of the limitations with current anatomical techniques for studying the auditory corticofugal system.

scholarly journals Correlation of neural response properties with auditory thalamus subdivisions in the awake marmoset

2011 ◽  
Vol 105 (6) ◽  
pp. 2647-2667 ◽  
Author(s):  
Edward L. Bartlett ◽  
Xiaoqin Wang
Keyword(s):  
Firing Rate ◽  
Functional Organization ◽  
Modulation Frequency ◽  
Medial Geniculate Body ◽  
Sound Level ◽  
Response Properties ◽  
Temporal Precision ◽  
Auditory Thalamus ◽  
Information Bottleneck ◽  
Medial Geniculate

As the information bottleneck of nearly all auditory input that reaches the cortex, the auditory thalamus serves as the basis for establishing auditory cortical processing streams. The functional organization of the primary and nonprimary subdivisions of the auditory thalamus is not well characterized, particularly in awake primates. We have recorded from neurons in the auditory thalamus of awake marmoset monkeys and tested their responses to tones, band-pass noise, and temporally modulated stimuli. We analyzed the spectral and temporal response properties of recorded neurons and correlated those properties with their locations in the auditory thalamus, thereby forming the basis for parallel output channels. Three medial geniculate body (MGB) subdivisions were identified and studied physiologically and anatomically, although other medial subdivisions were also identified anatomically. Neurons in the ventral subdivision (MGV) were sharply tuned for frequency, preferred narrowband stimuli, and were able to synchronize to rapid temporal modulations. Anterodorsal subdivision (MGAD) neurons appeared well suited for temporal processing, responding similarly to tone or noise stimuli but able to synchronize to the highest modulation frequencies and with the highest temporal precision among MGB subdivisions. Posterodorsal subdivision (MGPD) neurons differed substantially from the other two subdivisions, with many neurons preferring broadband stimuli and signaling changes in modulation frequency with nonsynchronized changes in firing rate. Most neurons in all subdivisions responded to increases in tone sound level with nonmonotonic changes in firing rate. MGV and MGAD neurons exhibited responses consistent with provision of thalamocortical input to core regions, whereas MGPD neurons were consistent with provision of input to belt regions.

Comparison of noise and tone azimuth tuning of neurons in cat primary auditory cortex and medical geniculate body

1995 ◽  
Vol 74 (3) ◽  
pp. 961-980 ◽  
Author(s):  
J. C. Clarey ◽  
P. Barone ◽  
W. A. Irons ◽  
F. K. Samson ◽  
T. J. Imig
Keyword(s):  
Auditory Cortex ◽  
Medial Geniculate Body ◽  
Primary Auditory Cortex ◽  
Broadband Noise ◽  
Statistical Analyses ◽  
Data Set ◽  
Degree Elevation ◽  
Level Data ◽  
Medial Geniculate ◽  
Ventral Nucleus

1. A comparison of the azimuth tuning of single neurons to broadband noise and to best frequency (BF) tone bursts was made in primary auditory cortex (AI: n = 173) and the medial geniculate body (MGB: n = 52) of barbiturate-anesthetized cats. Observations were largely restricted to cells located within the tonotopically organized divisions of the MGB (i.e., the ventral nucleus and the lateral division of the posterior nuclear group) and the middle layers of AI. All cells studied had BFs > or = 4 kHz. 2. The responses of each cell to sounds presented from seven frontal azimuthal locations (-90 to +90 degrees in 30 degrees steps; 0 degree elevation) and at five sound pressure levels (SPLs: 0-80 dB or 5-85 dB in 20-dB steps) provided an azimuth-level data set. Responses were averaged over SPL to obtain an azimuth function, and a number of features of this function were used to describe azimuth tuning to noise and to tone stimulation. Azimuth function modulation was used to assess azimuth sensitivity, and cells were categorized as sensitive or insensitive depending on whether modulation was > or = 75% or < 75% of maximum, respectively. The majority (88%) of cells in the sample were azimuth sensitive to noise stimulation, and statistical analyses were restricted to these cells, which are presumably best suited to encode sound source azimuth. Azimuth selectivity was assessed by a preferred azimuth range (PAR) over which azimuth function values exceeded 75% (PAR75) or 50% of maximum response. Cells were categorized according to the location and extent of their noise PARs. Unbounded cells had laterally located PARs that extended to the lateral pole (+/- 90 degrees); bounded cells had PARs that were contained entirely within the frontal hemifield, and a subset of these had PARs centered on the midline (+/- 15 degrees). A final group of cells exhibited multipeaked azimuth functions to noise stimulation. 3. Azimuth functions to noise were generally more selective and/or more sensitive than those to tones. Statistical analyses showed that these differences were significant for cells in each azimuth function category, and for the thalamic and cortical samples. With the exception of multipeaked cells, responsiveness to noise was significantly lower than that to tones in all categories, and for the thalamic and cortical samples.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Information flow in the rat thalamo-cortical system: spontaneous vs. stimulus-evoked activities

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kotaro Ishizu ◽  
Tomoyo I. Shiramatsu ◽  
Rie Hitsuyu ◽  
Masafumi Oizumi ◽  
Naotsugu Tsuchiya ◽  
...  
Keyword(s):  
Information Flow ◽  
Sensory Processing ◽  
Medial Geniculate Body ◽  
Primary Auditory Cortex ◽  
Stimulus Presentation ◽  
Dynamic Information ◽  
Information Theoretic ◽  
Medial Geniculate ◽  
Cortical System ◽  
Source Of Information

AbstractThe interaction between the thalamus and sensory cortex plays critical roles in sensory processing. Previous studies have revealed pathway-specific synaptic properties of thalamo-cortical connections. However, few studies to date have investigated how each pathway routes moment-to-moment information. Here, we simultaneously recorded neural activity in the auditory thalamus (or ventral division of the medial geniculate body; MGv) and primary auditory cortex (A1) with a laminar resolution in anesthetized rats. Transfer entropy (TE) was used as an information theoretic measure to operationalize “information flow”. Our analyses confirmed that communication between the thalamus and cortex was strengthened during presentation of auditory stimuli. In the resting state, thalamo-cortical communications almost disappeared, whereas intracortical communications were strengthened. The predominant source of information was the MGv at the onset of stimulus presentation and layer 5 during spontaneous activity. In turn, MGv was the major recipient of information from layer 6. TE suggested that a small but significant population of MGv-to-A1 pairs was “information-bearing,” whereas A1-to-MGv pairs typically exhibiting small effects played modulatory roles. These results highlight the capability of TE analyses to unlock novel avenues for bridging the gap between well-established anatomical knowledge of canonical microcircuits and physiological correlates via the concept of dynamic information flow.

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