The control of acoustic input in the medial geniculate body and inferior colliculus by auditory cortex

1970 ◽  
Vol 26 (1) ◽  
pp. 55-56 ◽  
Author(s):  
G. Amato ◽  
V. La Grutta ◽  
F. Enia
Keyword(s):  
Auditory Cortex ◽  
Inferior Colliculus ◽  
Medial Geniculate Body ◽  
Medial Geniculate

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 Sound Repetition Rate in the Human Auditory Pathway: Representations in the Waveshape and Amplitude of fMRI Activation

2002 ◽  
Vol 88 (3) ◽  
pp. 1433-1450 ◽  
Author(s):  
Michael P. Harms ◽  
Jennifer R. Melcher
Keyword(s):  
Auditory Cortex ◽  
Inferior Colliculus ◽  
Repetition Rate ◽  
Neural Coding ◽  
Medial Geniculate Body ◽  
Auditory Pathway ◽  
Stream Segregation ◽  
Neural Representation ◽  
Systematic Change ◽  
Medial Geniculate

Sound repetition rate plays an important role in stream segregation, temporal pattern recognition, and the perception of successive sounds as either distinct or fused. This study was aimed at elucidating the neural coding of repetition rate and its perceptual correlates. We investigated the representations of rate in the auditory pathway of human listeners using functional magnetic resonance imaging (fMRI), an indicator of population neural activity. Stimuli were trains of noise bursts presented at rates ranging from low (1–2/s; each burst is perceptually distinct) to high (35/s; individual bursts are not distinguishable). There was a systematic change in the form of fMRI response rate-dependencies from midbrain to thalamus to cortex. In the inferior colliculus, response amplitude increased with increasing rate while response waveshape remained unchanged and sustained. In the medial geniculate body, increasing rate produced an increase in amplitude and a moderate change in waveshape at higher rates (from sustained to one showing a moderate peak just after train onset). In auditory cortex (Heschl's gyrus and the superior temporal gyrus), amplitude changed somewhat with rate, but a far more striking change occurred in response waveshape—low rates elicited a sustained response, whereas high rates elicited an unusual phasic response that included prominent peaks just after train onset and offset. The shift in cortical response waveshape from sustained to phasic with increasing rate corresponds to a perceptual shift from individually resolved bursts to fused bursts forming a continuous (but modulated) percept. Thus at high rates, a train forms a single perceptual “event,” the onset and offset of which are delimited by the on and off peaks of phasic cortical responses. While auditory cortex showed a clear, qualitative correlation between perception and response waveshape, the medial geniculate body showed less correlation (since there was less change in waveshape with rate), and the inferior colliculus showed no correlation at all. Overall, our results suggest a population neural representation of the beginning and the end of distinct perceptual events that is weak or absent in the inferior colliculus, begins to emerge in the medial geniculate body, and is robust in auditory cortex.

A neural model of medial geniculate body and auditory cortex detecting target distance independently of target velocity in echolocation

2000 ◽  
Vol 32-33 ◽  
pp. 833-841 ◽  
Author(s):  
Satoru Inoue ◽  
Manabu Kimyou ◽  
Yoshiki Kashimori ◽  
Osamu Hoshino ◽  
Takeshi Kambara
Keyword(s):  
Auditory Cortex ◽  
Medial Geniculate Body ◽  
Neural Model ◽  
Target Distance ◽  
Target Velocity ◽  
Medial Geniculate

scholarly journals Inhibitory Projections from the Inferior Colliculus to the Medial Geniculate body Originate from Four Subtypes of GABAergic Cells

eNeuro ◽  
2018 ◽  
Vol 5 (5) ◽  
pp. ENEURO.0406-18.2018 ◽  
Author(s):  
N. L. Beebe ◽  
J. G. Mellott ◽  
B. R. Schofield
Keyword(s):  
Inferior Colliculus ◽  
Medial Geniculate Body ◽  
Medial Geniculate

Dual compartments of the ventral division of the medial geniculate body projecting to the core region of the auditory cortex in C57BL/6 mice

2013 ◽  
Vol 76 (4) ◽  
pp. 207-212 ◽  
Author(s):  
Masao Horie ◽  
Hiroaki Tsukano ◽  
Ryuichi Hishida ◽  
Hirohide Takebayashi ◽  
Katsuei Shibuki
Keyword(s):  
Auditory Cortex ◽  
Medial Geniculate Body ◽  
Core Region ◽  
The Core ◽  
Medial Geniculate
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