北アイルランド紛争“Troubles” の政治的起源 / 1920 年代における選挙制度改革をめぐって

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Auditory-cortex evoked potentials in WT and alpha-9-KO mice are similar.

<p>Grand average ACEPs obtained with 15 kHz tones delivered at 80 dB SPL in WT and alpha-9-KO mice. Note the latency and amplitude similarity of the ACEPs obtained in WT and alpha-9-KO mice. Gray and pink shaded areas represent the range of two standard deviation ± the mean of WT and alpha-9-KO mice correspondingly.</p

Schematic diagram of the experimental protocol used in WT and alpha-9-KO mice.

<p>A. In order to record auditory cortex evoked potentials (ACEP), a stereotrode was positioned in the left auditory cortex. This electrode was also used to perform the auditory-cortex electrical microstimulation (ACMS). Contralateral broad-band noise (CBN) was presented in the left pinna, while ipsilateral 15 kHz tones at 80 dB SPL in the right pinna. B. Temporal course of the experimental protocol. The effects of CBN were evaluated without (upper panel) and with ACMS (bottom panel). Auditory-brainstem responses (ABR) elicited by 15 kHz tone bursts were measured throughout the experimental protocol at 4 Hz rate. The period of contralateral acoustic stimulation is illustrated in green (120 to 240 s), while the ACMS period is depicted in pink (30 to 330 seconds).</p

Temporal course of corticofugal effects produced by ACMS on ABR waves in WT and alpha-9-KO mice.

<p>The grand averages of ABR obtained each 30 seconds of the protocol (a total 12 epochs per condition, each one computed from 120 responses) are displayed. Black circles represents ABR waves measured without ACMS, while red border white circles represent ABR waves obtained with ACMS. CBN were presented in both conditions between 120 and 240 seconds of the protocol. Asterisks represent significant effects of ACMS in different epochs of the experimental protocol (*p<0.05, repeated measures ANOVA, Bonferroni, post-hoc test). In addition, there were significant differences in the ABR wave-I amplitudes in the different epochs in WT (epoch 2 compared to epochs 5, 6 and 7 during simultaneous presentation of ACMS and CBN).</p

Schematic model of corticofugal effects on ABR waves.

<p>Red arrows represent descending pathways of the auditory efferent network. Orange arrows represent afferent connections of the ascending auditory pathways. From the obtained results, we propose that corticofugal effects on SOC (wave III) and auditory nerve (wave I) are driven through medial olivocochlear synapses on OHC. On the other hand, corticofugal effects on IC responses are mainly produced through direct connections (i), however indirect effects through MOC-OHC synapses, and then through ascending connections (ii) are also possible. IC: inferior colliculus; MGB: medial geniculate body; SOC: superior olivary complex; CN: cochlear nucleus.</p

Contralateral broad-band noise and ACMS produce larger reductions of ABR waveforms in WT than in alpha-9-KO mice.

<p>This figure shows examples of ABR obtained in WT and alpha-9-KO mice in three different conditions: control (black trace), with contralateral broad-band noise (green trace) and with CBN and ACMS (red trace). <b>A</b>. Note that the amplitudes of the ABR-waves (I, III and V) are clearly reduced in the WT mice, while smaller changes of ABR waves were observed in the alpha-9-KO mice.</p

Auditory-cortex electrical microstimulation enhances the suppressive effects of contralateral noise on ABR waves I and III in WT mice, but not in alpha-9-KO mice.

<p>This figure shows a summary of average corticofugal effects in all studied animals. Box-plots display the median and interquartile distribution of the effects of CBN in WT and alpha-9-KO mice without and with ACMS. The reference level for calculating amplitude changes in dB were the ABR amplitudes obtained without noise and without ACMS. Significant differences between WT and KO mice were obtained for CBN stimulation compared to the no noise and no ACMS condition for waves I and V (CBN effects: #p<0.05; two-way ANOVA). Significant differences were obtained for the effects of ACMS in WT mice for waves I, III and V and for wave V in alpha-9-KO mice. In addition, the effects of ACMS on wave III and V were larger for WT than for KO mice (genotype effects: *p<0.05; ACMS effects: **p<0.05; two-way ANOVA).</p