Fast frequency modulation is encoded according to the listener expectations in the human subcortical auditory pathway

Area of Science:

• Neuroscience
• Auditory Neuroscience
• Cognitive Neuroscience

Background:

• Expectations shape perception, aiding recognition and influencing communication.
• Previous research indicates expectations influence subcortical processing of static sounds.
• The role of expectations in subcortical encoding of dynamic acoustic features remains unclear.

Purpose of the Study:

• To investigate if subjective expectations drive the subcortical auditory pathway's encoding of fast frequency modulation (FM).
• To explore the neural basis of predictive processing in the human auditory system.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to measure brain activity.
• Neural responses were recorded in the auditory midbrain (inferior colliculus) and thalamus (medial geniculate body).
• Participants listened to frequency modulation (FM) sweeps under varying expectation conditions.

Main Results:

• Auditory midbrain and thalamus responses encoded the difference between acoustic input and listener expectations.
• Evidence suggests frequency modulation (FM) sweeps are encoded at the level of the human auditory midbrain.
• Encoding of FM sweeps was found to be primarily driven by subjective expectations.

Conclusions:

• The subcortical auditory pathway is integrated into the brain's predictive processing network.
• Subjective expectations optimize the encoding of dynamic acoustic elements in the auditory system.
• This research highlights the role of predictive coding in auditory perception.