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Differential representation of spectral and temporal information in primary auditory cortex (AI) of awake cats: relevance to auditory scene analysis
S208
Abstracts
The excitatory and inhibitory inputs had different temporal charactersitics: inhibitory inputs were similar in rise time (50% rise time, 32.8 ± 11.8(ms)), on the other hand, excitatory inputs had various rise times (50% rise time, 54.8 ± 63.3 (ms)) and seemed to contribute largely to the formation of diversity in temporal response patterns. doi:10.1016/j.neures.2009.09.1144
P3-b36 Mutual information between acoustic stimuli and optical signals in the primary auditory cortex Kazuya Saitoh, Masataka Nishimura, Wen-Jie Song Dept Sens Cogn Physiol, Kumamoto Univ, Kumamoto, Japan Neurons in the primary auditory cortex (AI) have always been shown in animal studies to be well tuned to pure tone stimuli. A recent study in human has revealed ultra-fine frequency tuning of AI neurons (Bitterman et al., 2008). While these studies suggest that AI is involved in representation of sound frequency, little is known about how well frequency is represented in AI. Here we obtained single-trial recordings of AI response to pure tones using real-time optical imaging with a voltage-sensitive dye, and argued about how well tone frequency is represented in AI using an information theory approach. Mutual information was calculated between AI optical signals and tonal stimuli when stimulus frequency was gradually changed from 8 kHz to 10.6 kHz (0.4 octave above 8 kHz). Mutual information significantly increased when the stimulus frequency was altered more than 7% (0.1 octave) of 8 kHz. These results suggest that tone frequency is represented in AI with an accuracy of several percent. doi:10.1016/j.neures.2009.09.1145
P3-c01 Differential representation of spectral and temporal information in primary auditory cortex (AI) of awake cats: relevance to auditory scene analysis Masashi Sakai, Sohei Chimoto, Ling Qin, Yu Sato Dept Physiol, Univ of Yamanashi, Yamanashi, Japan AI neurons (n = 92) were classified into 3 types based on the responses time-course to 0.5-s-long tone bursts: (1) P-cells (26%), giving only ON/OFF responses; (2) T-cells (34%), sustained responses with little adaptation; and (3) PT-cells (40%), sustained responses with some tendency of adaptation. Other tone-response variables differed between cell types: P-cells showed the shortest latency and smallest spiking jitter while T-cells had the sharpest frequency tuning. Between-cell-type differences were also evident for responses to click trains: a substantial fraction of P-cells conducted stimulus-locking responses, but none of T-cells did. Click-rate dependency of stimulus-locking responses resembled that reported for “comodulation masking release,” a behavioral model of auditory scene analysis. Collectively, it was suggested that: (1) T-cells preferentially encode spectral information with a rate-place code and (2) P-cells do acoustic transients with a temporal code, whereby rate-place coded information is potentially bound for scene analysis. doi:10.1016/j.neures.2009.09.1146
P3-c03 Plastic changes in the auditory fields induced by discrimination learning of synthetic vowels in rats Masaharu Kudoh, Go Ogawa Dept Physiol, Teikyo University Sch Med, Tokyo, Japan We have reported that discrimination learning of synthetic vowels with multiple formants was impaired by bilateral partial lesions of the rostral or dorsal auditory cortex (AC) in rats, while lesions of the primary AC had no effect. In the present study, plastic changes of AC responses to synthetic vowels by discrimination leaning were investigated using flavoprotein autofluorescence imaging. In naive rats, pure tones evoked clear flavoprotein fluorescence responses in the primary AC. However, synthetic formants or vowels evoked prominent responses in the anterior auditory field (AAF), which corresponds to the site of rostral AC lesions. In rats which had achieved the discrimination, the vowels used as S+ elicited stronger fluorescence responses in the AAF than those used as S−. We also found that potentiated activities to synthetic vowels were induced by discrimination learning in the dorsal region of AC. These findings suggest that the AAF and dorsal auditory fields play a critical role in discrimination learning of vowels in rats. doi:10.1016/j.neures.2009.09.1148
P3-c04 Neural mechanism of hierarchical processing of auditory information in mammal’s cortex Youichi Suzukawa 1 , Yoshiki Kashimori 1,2 1 Dept of Human Media Systems, Univ of Electro-Communications, Tokyo, 2 Dept of Applied Physics and Chemistry, Univ of ElectroJapan; Communications, Tokyo, Japan
Animals utilize auditory information for survival and communications of conspecifics. A sequence of sound is analyzed in animal’s brain as elementary components such as notes and syllables. It has been reported that auditory information is represented by spatiotemporal activity of primary auditory cortex. However, how the elementary components of sound are encoded from the spatiotemporal activity of neurons is poorly understood. To address this issue, we present a model of auditory cortex, which performs a hierarchical processing of auditory information. The model consists of three layers of 2-dimensional networks. We show that the aspects of the spatiotemporal activity in the primary cortex are encoded by a combination of feature-detective neurons and then by a dynamical attractor in higher order cortex. The present study provides a clue for understanding the mechanism of how the information of notes and syllables are constructed from spatiotemporal activity of the primary auditory cortex. doi:10.1016/j.neures.2009.09.1149
P3-c05 Analysis of indirect projections from ventral hippocampal field CA1 to the temporal auditory cortex in the rat Yoshiyuki Yamazaki 1 , Norio Ishizuka 2 , Minoru Tsukada 3 , Masahiko Takada 1 1
P3-c02 Involvement of neural recognition molecule NB-2 in the development of auditory brainstem Manabu Toyoshima 1 , Kunie Sakurai 1 , Yasuo Takeda 3 , Kuniko Shimazaki 2 , Yashushi Shimoda 1 , Kazutada Watanabe 1 1
2
Dept Bioeng, Nagaoka Univ Tech, Niigata, Japan; Dept Physiol, Jichi Med Univ, Tochigi, Japan; 3 Dept Clinic Pharm & Pharmacol, Kagoshima Univ, Grad Sch Med & Dent Sci, Kagoshima, Japan NB-2 is a neural cell recognition molecule of the contactin subgroup. We reported previously that NB-2 expression is prominent in the glutamatergic neuron of auditory brainstem during early postnatal development. This suggests that NB-2 might play important roles in the development of auditory brainstem. Here, we compared the postnatal development of the auditory brainstem between NB-2 knockout (KO) and wild-type mice. In NB-2 KO mouse at P6, approximately 10% of the calyces of Held in the medial nucleus of the trapezoid body (MNTB) were negative for VGLUT1, whereas all calyces were VGLUT1 positive in wild type mouse. In addition, a subset of principal neurons in the MNTB underwent apoptosis in NB-2 KO mouse at P15, despite that no apoptotic principal neuron was detected in wild type mouse. Thus, NB-2 plays a important role in the development of glutamatergic synapses and principal neurons in the MNTB of the auditory brainstem. doi:10.1016/j.neures.2009.09.1147
Dept System Neurosci, Tokyo Met Inst Neurosci, Tokyo, Japan; 2 Dept Brain Struct, Tokyo Met Inst Neurosci, Tokyo, Japan; 3 Brain Sci Inst, Tamagawa Univ, Tokyo, Japan The hippocampal-neocortical system plays a critical role in declarative memory processing. Charting the connections within this system is essential to understand the mechanism that underlies such memory formation. In the present study, the organization of multisynaptic projections from hippocampal field CA1 to the temporal auditory cortex was examined in the rat by means of retrograde transsynaptic transport of rabies virus. After injection into the primary auditory area, transneuronal labeling of CA1 pyramidal cells was seen exclusively in the ventral two thirds of the hippocampus as second- or third-order neurons. In rats with excitotoxic lesions of the basolateral amygdala, the number of labeled pyramidal cells was considerably reduced as compared to control cases without amygdalar lesions. These results indicate a specific role of the ventral CA1 and basolataral amygdala in memory formation processing in the hippocampal-neocortical system. doi:10.1016/j.neures.2009.09.1150
P3-c06 Inhibitory tectothalamic neurons receive a specialized glutamatergic synapse Tetsufumi Ito 1,2 , Hye Sook Ahn 2 , Deborah Bishop 2 , Yuchio Yanagawa 3 , Douglas L. Oliver 2 1
Div Anat, Univ Fukui, Japan; 2 Dept Neurosci, UCHC, USA; Behav Neurosci, Gunma Univ Grad Sch Med, Japan
3
Dept Genet
Abstracts
The excitatory and inhibitory inputs had different temporal charactersitics: inhibitory inputs were similar in rise time (50% rise time, 32.8 ± 11.8(ms)), on the other hand, excitatory inputs had various rise times (50% rise time, 54.8 ± 63.3 (ms)) and seemed to contribute largely to the formation of diversity in temporal response patterns. doi:10.1016/j.neures.2009.09.1144
P3-b36 Mutual information between acoustic stimuli and optical signals in the primary auditory cortex Kazuya Saitoh, Masataka Nishimura, Wen-Jie Song Dept Sens Cogn Physiol, Kumamoto Univ, Kumamoto, Japan Neurons in the primary auditory cortex (AI) have always been shown in animal studies to be well tuned to pure tone stimuli. A recent study in human has revealed ultra-fine frequency tuning of AI neurons (Bitterman et al., 2008). While these studies suggest that AI is involved in representation of sound frequency, little is known about how well frequency is represented in AI. Here we obtained single-trial recordings of AI response to pure tones using real-time optical imaging with a voltage-sensitive dye, and argued about how well tone frequency is represented in AI using an information theory approach. Mutual information was calculated between AI optical signals and tonal stimuli when stimulus frequency was gradually changed from 8 kHz to 10.6 kHz (0.4 octave above 8 kHz). Mutual information significantly increased when the stimulus frequency was altered more than 7% (0.1 octave) of 8 kHz. These results suggest that tone frequency is represented in AI with an accuracy of several percent. doi:10.1016/j.neures.2009.09.1145
P3-c01 Differential representation of spectral and temporal information in primary auditory cortex (AI) of awake cats: relevance to auditory scene analysis Masashi Sakai, Sohei Chimoto, Ling Qin, Yu Sato Dept Physiol, Univ of Yamanashi, Yamanashi, Japan AI neurons (n = 92) were classified into 3 types based on the responses time-course to 0.5-s-long tone bursts: (1) P-cells (26%), giving only ON/OFF responses; (2) T-cells (34%), sustained responses with little adaptation; and (3) PT-cells (40%), sustained responses with some tendency of adaptation. Other tone-response variables differed between cell types: P-cells showed the shortest latency and smallest spiking jitter while T-cells had the sharpest frequency tuning. Between-cell-type differences were also evident for responses to click trains: a substantial fraction of P-cells conducted stimulus-locking responses, but none of T-cells did. Click-rate dependency of stimulus-locking responses resembled that reported for “comodulation masking release,” a behavioral model of auditory scene analysis. Collectively, it was suggested that: (1) T-cells preferentially encode spectral information with a rate-place code and (2) P-cells do acoustic transients with a temporal code, whereby rate-place coded information is potentially bound for scene analysis. doi:10.1016/j.neures.2009.09.1146
P3-c03 Plastic changes in the auditory fields induced by discrimination learning of synthetic vowels in rats Masaharu Kudoh, Go Ogawa Dept Physiol, Teikyo University Sch Med, Tokyo, Japan We have reported that discrimination learning of synthetic vowels with multiple formants was impaired by bilateral partial lesions of the rostral or dorsal auditory cortex (AC) in rats, while lesions of the primary AC had no effect. In the present study, plastic changes of AC responses to synthetic vowels by discrimination leaning were investigated using flavoprotein autofluorescence imaging. In naive rats, pure tones evoked clear flavoprotein fluorescence responses in the primary AC. However, synthetic formants or vowels evoked prominent responses in the anterior auditory field (AAF), which corresponds to the site of rostral AC lesions. In rats which had achieved the discrimination, the vowels used as S+ elicited stronger fluorescence responses in the AAF than those used as S−. We also found that potentiated activities to synthetic vowels were induced by discrimination learning in the dorsal region of AC. These findings suggest that the AAF and dorsal auditory fields play a critical role in discrimination learning of vowels in rats. doi:10.1016/j.neures.2009.09.1148
P3-c04 Neural mechanism of hierarchical processing of auditory information in mammal’s cortex Youichi Suzukawa 1 , Yoshiki Kashimori 1,2 1 Dept of Human Media Systems, Univ of Electro-Communications, Tokyo, 2 Dept of Applied Physics and Chemistry, Univ of ElectroJapan; Communications, Tokyo, Japan
Animals utilize auditory information for survival and communications of conspecifics. A sequence of sound is analyzed in animal’s brain as elementary components such as notes and syllables. It has been reported that auditory information is represented by spatiotemporal activity of primary auditory cortex. However, how the elementary components of sound are encoded from the spatiotemporal activity of neurons is poorly understood. To address this issue, we present a model of auditory cortex, which performs a hierarchical processing of auditory information. The model consists of three layers of 2-dimensional networks. We show that the aspects of the spatiotemporal activity in the primary cortex are encoded by a combination of feature-detective neurons and then by a dynamical attractor in higher order cortex. The present study provides a clue for understanding the mechanism of how the information of notes and syllables are constructed from spatiotemporal activity of the primary auditory cortex. doi:10.1016/j.neures.2009.09.1149
P3-c05 Analysis of indirect projections from ventral hippocampal field CA1 to the temporal auditory cortex in the rat Yoshiyuki Yamazaki 1 , Norio Ishizuka 2 , Minoru Tsukada 3 , Masahiko Takada 1 1
P3-c02 Involvement of neural recognition molecule NB-2 in the development of auditory brainstem Manabu Toyoshima 1 , Kunie Sakurai 1 , Yasuo Takeda 3 , Kuniko Shimazaki 2 , Yashushi Shimoda 1 , Kazutada Watanabe 1 1
2
Dept Bioeng, Nagaoka Univ Tech, Niigata, Japan; Dept Physiol, Jichi Med Univ, Tochigi, Japan; 3 Dept Clinic Pharm & Pharmacol, Kagoshima Univ, Grad Sch Med & Dent Sci, Kagoshima, Japan NB-2 is a neural cell recognition molecule of the contactin subgroup. We reported previously that NB-2 expression is prominent in the glutamatergic neuron of auditory brainstem during early postnatal development. This suggests that NB-2 might play important roles in the development of auditory brainstem. Here, we compared the postnatal development of the auditory brainstem between NB-2 knockout (KO) and wild-type mice. In NB-2 KO mouse at P6, approximately 10% of the calyces of Held in the medial nucleus of the trapezoid body (MNTB) were negative for VGLUT1, whereas all calyces were VGLUT1 positive in wild type mouse. In addition, a subset of principal neurons in the MNTB underwent apoptosis in NB-2 KO mouse at P15, despite that no apoptotic principal neuron was detected in wild type mouse. Thus, NB-2 plays a important role in the development of glutamatergic synapses and principal neurons in the MNTB of the auditory brainstem. doi:10.1016/j.neures.2009.09.1147
Dept System Neurosci, Tokyo Met Inst Neurosci, Tokyo, Japan; 2 Dept Brain Struct, Tokyo Met Inst Neurosci, Tokyo, Japan; 3 Brain Sci Inst, Tamagawa Univ, Tokyo, Japan The hippocampal-neocortical system plays a critical role in declarative memory processing. Charting the connections within this system is essential to understand the mechanism that underlies such memory formation. In the present study, the organization of multisynaptic projections from hippocampal field CA1 to the temporal auditory cortex was examined in the rat by means of retrograde transsynaptic transport of rabies virus. After injection into the primary auditory area, transneuronal labeling of CA1 pyramidal cells was seen exclusively in the ventral two thirds of the hippocampus as second- or third-order neurons. In rats with excitotoxic lesions of the basolateral amygdala, the number of labeled pyramidal cells was considerably reduced as compared to control cases without amygdalar lesions. These results indicate a specific role of the ventral CA1 and basolataral amygdala in memory formation processing in the hippocampal-neocortical system. doi:10.1016/j.neures.2009.09.1150
P3-c06 Inhibitory tectothalamic neurons receive a specialized glutamatergic synapse Tetsufumi Ito 1,2 , Hye Sook Ahn 2 , Deborah Bishop 2 , Yuchio Yanagawa 3 , Douglas L. Oliver 2 1
Div Anat, Univ Fukui, Japan; 2 Dept Neurosci, UCHC, USA; Behav Neurosci, Gunma Univ Grad Sch Med, Japan
3
Dept Genet