IC and MGB Flashcards
What is the major nucleus between the SOC and IC? Is it obligatory? What nucleus is it physiologically similar to?
The major nucleus between the SOC and the IC is the Lateral Lemniscus (LL). The LL is not obligatory since the cochlear nucleus directly innervates the inferior colliculus. The LL is physiologically similar to the Interior Colliculus.
What is the purpose of ICC? ICX? ICD?
The central nucleus of the Inferior Colliculus (ICC) is part of the core ascending auditory pathway. It receives primary input from excitatory (contralateral CN and LSO; ipsilateral MSO) and inhibitory pathways (ipsilateral LSO and NLL).
The external nucleus of the inferior colliculus (ICX) plays a role in multisensory integration. It receives input from the ICC and somatosensory dorsal column nuclei and trigeminal nucleus (head and neck).
The dorsal cortex of the interior colliculus (ICD) receives descending inputs from the auditory cortex. In turn, it projects in the ICC.
Explain the tonotopicity of the IC.
The inferior colliculus has iso-frequency sheets. Low frequencies are more laterally located and high frequencies are more medially located.
How do TCs in ICC compare to AN? ICD vs AN?
The tuning curves are sharper in the ICC compared to the AN. The tuning curves are broader in the ICD compared to the AN.
List three stimulus properties that we start to get tuning to at the level of the IC.
At the level of the IC, there is the start of tuning to the following temporal characteristics: rise-fall time, duration, AM rate, FM rate, and AM/FM sweep direction.
Stimulus duration
Tuning to amplitude and frequency modulations are really important
Neurons are tuned to a best modulation.
What is the limit of phase locking in the IC?
The limit of phase locking is up to 600 Hz.
What are the three main sections of the MGB? Which is the main auditory relay?
The three main sections of the Medial Geniculate Body are the dorsal, medial, and ventral. The ventral division is the main auditory relay.
What is the limit of phase locking in the MGB?
The limit of phase locking in the MGC for the majority of neurons is up to 250 Hz. Only 10% of neurons can phase lock up to 1000 Hz.
Outputs from the MGB go where?
Outputs from the MGB go to the auditory cortex.
