Anatomical correlates of absolute pitch studied by VBM

Abstracts The inferior colliculus (IC) integrates all information about sound before transmitting it to cortical levels. In the CNS, the IC is unusual since both glutamatergic and GABAergic output neurons transmit auditory information to the thalamus, and inhibitory potentials arrive in the thalamus before excitatory potentials. However, the mechanisms that drive this inhibitory output are unclear. Here, we show that the largest GABAergic neurons in IC have specialized VGLUT2-positive synapses that surround the cell body and proximal dendrites, while smaller GABAergic neurons do not. They also differ in their membrane properties. The vast majority of GABAergic tectothalamic neurons receive these calyx-like terminals that resemble the dense, axosomatic, glutamatergic synapses of the lower auditory brainstem. Thus, the IC contains two types of GABAergic neurons, and one has a distinct synaptic architecture that plays a unique roll in the transmission of inhibition to the auditory thalamus. doi:10.1016/j.neures.2009.09.1151

P3-c07 Optical imaging of visual-auditory multimodal fields in the guinea-pig auditory cortex Keigo Hobara, Shinya Yamada, Shunji Sugimoto, Junsei Horikawa Dept of Knowledge-based Infomation Engineering, Toyohashi Univ of Technology, Japan While a recent electrophysiological study has shown that neuronal responses to visual stimuli appear in the auditory cortex, their detailed distribution and functions have not yet been clarified. In this study, to identify visual-auditory multimodal cortical fields, we investigated spatiotemporal response patterns in the guinea-pig auditory cortex by optical imaging with a voltage-sensitive dye. As stimulation we used a blue LED light and a white-noise burst, which were presented alone or simultaneously. Visual-auditory multimodal fields were found in a part of auditory core fields, especially in the borderline between the primary (AI) and dorsocaudal (DC) areas, and in the surrounding belt fields. In these multimodal fields, latency of responses evoked by single visual stimuli was longer than that of responses to single auditory stimuli or simultaneous visual-auditory stimuli. The present results showed spatiotemporal response patterns for the processing of multi-sensory inputs in the auditory cortex. doi:10.1016/j.neures.2009.09.1152

P3-c08 Anatomical correlates of absolute pitch studied by VBM Nobuko Hara 1 , Tatsuya Mima 2 1

DEA Saclay NeuroSpin, France; 2 Kyoto University Graduate School of Mericine, Department of Brain Pathophysiology, Human Brain Research Center, Japan A kind of absolute pitch (AP) possessors known as genuine-AP who can distinguish the pitch names of chords as well as tones, while others cannot. Such genuine AP is thought to be hereditary and possibly be linked to brain structure. Previous studies have implicated the planum temporale (PT) in musical tone processing, however, the brain anatomy of genuine-AP has not been fully clarified yet. Right-handed and musically trained 45 subjects were scanned using T1 MPRAGE (Siemens Allegra 3T). Voxel-based morphometry was performed using SPM2. Two solfege tests were used for screening genuine AP, pseudo-AP and non-AP possessors. Our data revealed that the left PT was larger in genuine AP than the others. By contrast, pseudo-AP group had stronger GM concentrations in the posterior region of the right PT than the others. These results suggest that the left PT can be the biological substrate of consistent pitch perception of genuine-AP. This divergence indicates that the brain mechanism for pitch perception in genuine and pseudo-AP may be different. doi:10.1016/j.neures.2009.09.1153

P3-c09 Characteristic physiological responses to alternating tone sequences in auditory cortex Takahiro Noda 1 , Ryohei Kanzaki 1 , Hirokazu Takahashi 1,2 1 Graduate school of Information science and Technology, Univ of Tokyo, Tokyo, Japan; 2 PRESTO, JST Kawaguchi, Saitama, Japan

Auditory system can separate sounds into several perceptual objects, termed stream, the mechanism of which remains unknown. Psychophysical evidence reveals that when ABA-tone sequence with various frequency differences between A and B tones (F) and inter tone intervals (ITI) are presented, sequences with larger F and smaller ITI tend to induce stream segregation. In this study, local field potentials (LFPs) of rat auditory cortex were mapped, and the responses at A-tone-evoked local foci were characterized. The amplitude in response to B tone varied nonmonotonically as a function of F, and had a local maximum when F was 50–60% of A-tone frequency, suggesting that this enhanced representation of B tone leads

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to ambiguous perception of A tone. Furthermore, the amplitude and temporal variability of the response evoked by the second A tone decreased for the larger F and longer ITI, suggesting that these test conditions stabilize perception of A tone and maintain the perception of temporal order of A-B tones. doi:10.1016/j.neures.2009.09.1154

P3-c10 Brain activities involved in audiomotor integration for manual pitch regulation Ryosuke Tachibana 1 , Masuzo Yanagida 2 , Hiroshi Riquimaroux 1 1

Grad. Sch. of Life and Medical Sci, Doshisha Univ, Japan; Eng., Doshisha Univ, Japan

2

Grad. Sch. of

This study examines the brain activities involved in sensorimotor integration for a simple audiomotor task, in which tone pitch is controlled by subject’s fingers pressing a force sensor. Subjects were instructed to regulate the feedback pitch to fit the target pitch while the brain activities were measured by fMRI. An auditory task where subjects just listened to sound stimuli without physical action, and a motor task in which they were asked to apply target force on the sensor without auditory feedback were also performed. As results, significantly greater activations were observed in the primary motor area, the ventral premotor cortex, the posterior superior temporal plane (pSTP), the primary auditory area, the putamen, and the posterior lobe of cerebellum for the audiomotor task comparing to the auditory and the motor task. Further analyses show that the pSTP activity is correlated with the amount of pitch adjustment. This finding suggests that the pSTP is an important neural substrate for transforming pitch error into corrective motor command. doi:10.1016/j.neures.2009.09.1155

P3-c11 The effect of lemon odor on restraint stress-induced c-Fos expression in hypothalamic paraventricular neurons of rats Kazue Sanada, Fumihiro Shutoh, Setsuji Hisano Laboratory of Neuroendocrinology, Institute of Basic Medical Sciences, University of Tsukuba, Tsukuba, Japan The aim of this study is to investigate an effect of odors on the c-Fos expression level in the hypothalamic paraventricular nucleus (PVN) of rats exposed to stress. Adult male Sprague-Dawley rats were subjected to a 30-min restraint stress, while being exposed to either lemon odor (n = 5) or air (n = 5). The odor was given through an air-stream (4 L/min). Two hours after initiation of restraint, they were perfusionfixed under deep anesthesia, brains were dissected out and cut into 5-␮m thick coronal sections. c-Fos was detected by immunohistochemistry and the number of positive paraventricular neurons was counted. The number of positive neurons was significantly smaller in the lemon odor group than in the air group (p < 0.01). This result suggests that lemon odor has an inhibitory effect on the restraint stressinduced activation of the hypothalamus–pituitary–adrenal axis. doi:10.1016/j.neures.2009.09.1156

P3-c12 Noradrenergic modulation of Ca2+ signaling in the accessory olfactory bulb neurons Keiko Moriya-Ito, Masumi Ichikawa Dept of Neurosci Basic Tech, Tokyo Met Inst for Neurosci, Japan The mammalian accessory olfactory bulb (AOB) receives a significant noradrenergic (NA) input from the locus ceruleus. NA modulation of dendrodendritic synapses between the mitral/tufted and granule cells in AOB is postulated to play a key role in the formation of pheromonal memory arising from mating. The mechanisms by which the neuromodulater bring about the synaptic changes are not clearly understood. In other to study the signaling that mediate synaptic plasticity in the AOB, we performed Ca imaging using primary culture of AOB. Application of NA (10 ␮M) induced a transient Ca2+ increase of astrocytes that was blocked by ␣1 adrenoceptor antagonist. The Ca2+ responses of NA application in AOB neurons were not homogeneous. In some mitral/tufted cell, slow Ca2+ increase was appeared, and the Ca2+ level was maintained. In granule cells, spontaneous Ca2+ oscillation cycles were variously changed. Since these neuronal Ca2+ alterations by NA occurred following by Ca2+ changes of astrocytes, it had been suggested NA modulate AOB neuronal activity also indirectly via astrocytes. doi:10.1016/j.neures.2009.09.1157