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Tone-sequence analysis in the auditory cortex of awake macaque monkeys
Michael Brosch1, Henning Scheich
1Leibniz-Institut für Neurobiologie, Brenneckestrasse 6, 3911, Magdeburg, Germany. brosch@ifn-magdeburg.de
Experimental Brain Research
|September 14, 2007
Summary
Investigating auditory cortex neuronal responses to two-tone sequences in awake macaques revealed that the first tone influences the second tone
Area of Science:
- Neuroscience
- Auditory Neuroscience
- Sensory Processing
Background:
- Neuronal responses in the auditory cortex are crucial for processing complex sounds.
- Understanding sequence sensitivity in the auditory cortex is key to deciphering auditory perception.
- Previous studies often used anesthetized animals, limiting applicability to awake states.
Purpose of the Study:
- To analyze neuronal responses to two-tone auditory sequences in awake macaque monkeys.
- To determine how sequence parameters affect neuronal inhibition and facilitation.
- To compare findings in awake animals with previous studies in anesthetized preparations.
Main Methods:
- Recorded multiunit activity from 109 sites in the primary auditory cortex and posterior auditory belt.
- Exposed three awake macaque monkeys to 430 systematically varied two-tone sequences.
- Varied the frequency of the first tone and the interval between tones, keeping the second tone constant.
Main Results:
- The first tone in a sequence could significantly inhibit or facilitate neuronal responses to the second tone.
- The nature and extent of these poststimulatory effects were dependent on sequence parameters.
- Effects correlated with the single-tone frequency sensitivity of individual neurons.
Conclusions:
- Neuronal sequence sensitivity in the auditory cortex of awake macaques shares similarities with anesthetized preparations.
- Anesthetics appear to cause only moderate changes in poststimulatory inhibition and facilitation.
- Findings suggest that studies on anesthetized animals provide valuable insights into auditory cortex function in awake subjects.
Related Concept Videos
01:15Auditory 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...
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01:13The 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.
01:31Hearing
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.