Scientific Understanding of Consciousness
Consciousness as an Emergent Property of Thalamocortical Activity

Auditory System


Research Study — Speech Sensory–Motor Transformations occur Bilaterally

Research Study — Ear Ossicles Development

Research Study — Auditory Cortices Phonetic Representation and Left Frontal Phonological

Research Study — Auditory Cortical Processing Modulated by Movement


Auditory System -- from Ear to Cortex (Pinel; Anatomy of Human Brain, 138)

Cortical Auditory Areas (Pinel; Anatomy of Human Brain, 140)

Visual,    auditory,    and somatosensory information is input to the cortex via the thalamus. (Arbib - Handbook of Brain Theory and Neural Networks; Mumford; Thalamus, 981)


Auditory information processing in cochlear, reticular formation, and auditory cortex

Brain automatically fills-in sound that is missing due to noise. [Gestalts]

Auditory Parallelization in Cochlea

The auditory process of parallelization is essential because the potential information rate in the acoustic stimulus is of the order of 0.5 Mb per second, and yet typical auditory nerve fibers have maximum sustained firing rates of 200 Bits per second. (Mountain; Auditory Periphery, 115)

The cochlea takes a serial time signal and converts it into parallel signals in the form of the mechanical stimuli to the hair bundles in the hair cells located in the organ of Corti. (Mountain; Auditory Periphery, 115)

The inner hair cell (IHC) receptor potential is a rectified and low pass filtered version of the mechanical stimulus, with an amplitude roughly proportional to the log of the stimulus power. (Mountain; Auditory Periphery, 115)

A typical mammalian cochlea will have around 2000 IHC's. (Mountain; Auditory Periphery, 115)

Three Pathways in Series

Hierarchy of three pathways in series through which the information passes on its afferent journey through the CNS. (1) Reticular formation,  (2) Thalamus, (3) Cortex.  (Schneck & Berger; Music Effect, 86)

(1) Reticular formation

Reticular formation -- first level of information processing. (Schneck & Berger; Music Effect, 86)

Primary function of the reticular formation is to prevent information overload by acting as a preliminary coarse sieve or filter that serves to avoid innundating the brain with information. (Schneck & Berger; Music Effect, 86)

(2) Thalamus

Thalamus -- sensory reception center; evaluates incoming information; once classified, immediately dispatched to two generic places: (1) sensory regions of the cerebral cortex, (2) the limbic system, where it undergoes immediate, subconscious perception to effect instantaneous responses to potential threats. (Schneck & Berger; Music Effect, 86)

Sensory data the thalamus has classified as potential threats passes in series pathways first through the amygdala and second through the hippocampus. (Schneck & Berger; Music Effect, 87)

If the amygdala signifies that all is well, information filtered by the RAS, classified by the thalamus, and evaluated and prioritized by the limbic system passes on through the hippocampus to the cognitive regions of the cerebral cortex. (Schneck & Berger; Music Effect, 88)

(3) Cortex

Brain attempts to economize on the utilization of space for storage: (1) it stores ingredients, not products, (2) it draws upon fractal principles to create complicated geometric shapes and configurations, (3) it discards any and all information for which it has no perceived need. (Schneck & Berger; Music Effect, 89)



A good reference for the auditory system. (Purves, Neuroscience, 283)


The anatomy of the auditory cortex suggests that following the succession of nuclei in the subcortical pathway, the information in the auditory cortex radiates out in parallel paths from core areas and cascades into at least three spatially distributed sensor regions, comprising at least three further processing stages. Prominent feedback routes connect adjacent regions at all levels. Perceptual processes must depend on this anatomical organization. (Moore,, Perception of Speech, 175)


Link to — Topics for Speech Perception


Cochlear Nucleus chapter. (Shepherd; Synaptic Organization of the Brain, 121)

Drawing of the auditory periphery (diagram), external ear middle ear, inner ear; three middle ear ossicles: malleus, incus, stapes; inner ear: cochlea of the auditory system, semi circular canals of the vestibular system. (Squire; Fundamental Neuroscience, 700)


Auditory Perception and Music

Link to — Auditory Perception and Music


Return to — Sensory Input