Related Experiment Video
Updated: Jul 2, 2026

11:19
Extracellular Recording of Neuronal Activity Combined with Microiontophoretic Application of Neuroactive Substances in Awake Mice
Published on: May 21, 2016
Auditory frequency-following responses in rat ipsilateral inferior colliculus
Junli Ping1, Nanxin Li, Gary C Galbraith
1Department of Psychology, Peking University, Beijing 100871, China. liangli@pku.edu.cn
Neuroreport
|September 4, 2008
Summary
Auditory frequency-following responses (FFRs) in the inferior colliculus are influenced by neural pathways. Excitatory projections from the contralateral inferior colliculus facilitate FFRs, while inhibitory projections suppress them.
Area of Science:
- Neuroscience
- Auditory Neuroscience
- Neurophysiology
Background:
- Auditory frequency-following responses (FFRs) reflect neural activity phase-locked to sound.
- Neurons in the rat inferior colliculus respond to auditory stimuli from either ear.
Purpose of the Study:
- To investigate the neural mechanisms underlying ipsilaterally elicited FFRs in the rat inferior colliculus.
- To determine the role of contralateral pathways in modulating these responses.
Main Methods:
- Elicitation of FFRs using pure tone bursts (225-4025 Hz) at the ipsilateral ear in anesthetized rats.
- Pharmacological manipulation of glutamate transmission in the contralateral inferior colliculus.
- Pharmacological manipulation of the contralateral dorsal nucleus of the lateral lemniscus.
Main Results:
- Ipsilaterally driven FFRs in the inferior colliculus were observed.
- Chemical blockade of contralateral inferior colliculus glutamate transmission reduced ipsilateral FFRs.
- Blocking the contralateral dorsal nucleus of the lateral lemniscus enhanced ipsilateral FFRs.
Conclusions:
- Ipsilateral FFRs in the inferior colliculus are facilitated by excitatory contralateral inferior colliculus projections.
- Inhibitory projections from the contralateral dorsal nucleus of the lateral lemniscus suppress these FFRs.
Related Concept Videos
The Cochlea
The cochlea is a coiled structure in the inner ear that contains hair cells—the sensory receptors of the auditory system. Sound waves are transmitted to the cochlea by small bones attached to the eardrum called the ossicles, which vibrate the oval window that leads to the inner ear. This causes fluid in the chambers of the cochlea to move, vibrating the basilar membrane.
Auditory Pathway
Auditory pathways constitute the complex neural circuits responsible for transmitting and interpreting auditory information from the peripheral auditory system to the brain. Sound waves are initially captured by the outer ear, funneled through the ear canal, and reach the tympanic membrane (eardrum). These vibrations are transmitted via the middle ear's ossicles to the inner ear's cochlea.
When viewed cross-sectionally, the cochlea reveals the scala vestibuli and scala tympani flanking the...
When viewed cross-sectionally, the cochlea reveals the scala vestibuli and scala tympani flanking the...
Hearing
When we hear a sound, our nervous system is detecting sound waves—pressure waves of mechanical energy traveling through a medium. The frequency of the wave is perceived as pitch, while the amplitude is perceived as loudness.
Perceiving Loudness, Pitch, and Location
The human brain perceives pitch through two primary mechanisms reflected in place theory and frequency theory. Each mechanism describes how sound waves are interpreted as specific pitches by the brain, offering insights into the intricate processes of auditory perception.
Place theory, or place coding, suggests that different pitches are heard because various sound waves activate specific locations along the cochlea's basilar membrane. The brain determines the pitch of a sound by identifying...
Place theory, or place coding, suggests that different pitches are heard because various sound waves activate specific locations along the cochlea's basilar membrane. The brain determines the pitch of a sound by identifying...

