What is meant by a Tonotopic map?
Tonotopic maps are a striking feature of the mammalian auditory cortex and underlie the representation of complex sounds, such as speech. This spatial separation of frequencies originates in the inner ear, where high frequencies are processed in the base of the cochlea and low frequencies in the apex.
What is Tonotopic organization?
Tonotopic organization means that cells responsive to different frequencies are found in different places at each level of the central auditory system, and that there is a standard (logarithmic) relationship between this position and frequency. Each cell has a characteristic frequency (CF).
What is the auditory pathway?
The auditory pathway starts at the cochlear nucleus, then the superior olivary complex, then the inferior colliculus, and finally the medial geniculate nucleus. The information is decoded and integrated by each relay nucleus in the pathway and finally projected to the auditory cortex.
How does auditory transduction occur?
In auditory transduction, auditory refers to hearing, and transduction is the process by which the ear converts sound waves into electric impulses and sends them to the brain so we can interpret them as sound.
Why is tonotopic mapping important?
Mechanisms of cochlear tonotopy Hair bundles, or the “mechanical antenna” of hair cells, are thought to be particularly important in cochlear tonotopy. The morphology of hair bundles likely contributes to the BM gradient. Tonotopic position determines the structure of hair bundles in the cochlea.
Where does tonotopic organization occur?
cochlea
Tonotopy is a key organizational feature of the vertebrate auditory system. Also referred to as cochleotopy, it arises in the cochlea of the inner ear, which acts as a bank of parallel filters that are sharply tuned to neighboring frequencies (von Bekesy 1949).
What is the pathway of sound vibrations to the inner ear?
The vibrations are transmitted further into the ear via three bones (ossicles): malleus (hammer), incus (anvil), and the stapes (stirrup). These three bones form a bridge from the tympanic membrane to the oval window. 5. Once sound passes through the oval window, it enters into the cochlea in the inner ear.
How does the brain process auditory signals?
The brainstem and thalamus use the information from both ears to compute a sound’s direction and location. In the primary auditory cortex different auditory neurons respond to different frequencies, which maintains the frequency map generated by the hair cells.
Where does sensory transduction occur?
The most fundamental function of a sensory system is the translation of a sensory signal to an electrical signal in the nervous system. This takes place at the sensory receptor. The change in electrical potential that is produced is called the receptor potential.
What is responsible for sensory transduction in the auditory system?
The site of transduction is in the organ of Corti (spiral organ). It is composed of hair cells held in place above the basilar membrane like flowers projecting up from soil, with their exposed short, hair-like stereocilia contacting or embedded in the tectorial membrane above them.
What is tonotopic gradient?
This organization, referred to as tonotopy or cochleotopy, mirrors the distribution of receptors in the cochlea, with a gradient extending between neurons that preferentially respond to high frequencies and those that respond best to low frequencies.
Why is tonotopic organization important?
In most modern tetrapods, tonotopic organization is a key feature of the central auditory system. Each point on the basilar membrane projects to an iso-frequency plane across the extent of the first order auditory nuclei.