Lecture 9

Periodotopic Gradient

orderly representation of temporal (periodicity) information across topologically neighboring neurons in auditory cortex

Basilar Membrane

the basilar membrane with the cochlea of the inner ear is a stiff structural element that separates two liquid-filled tubes that run along the coil of the cochlea, forming a base for the hair cells to transduce the sound waves in the cochlear fluid to electrochemical signals in the brain

Cochlea

the coiled and channeled main structure of the inner ear, which contains three fluid-filled canals that run along its entire convoluted length; the fluid-filled canals are separates by membranes, one of which is the basilar membrane, on which thousands of hair cells (auditory receptors) are arranged and are stimulated by the vibrations of the stapes

Incus

the incus or anvil is the anvil-shaped small bone or ossicle in the middle ear. It connects the malleus to the stapes.

Lateral Sulcus

the lateral sulcus (also called Sylvian fissure or lateral fissure;fissure=large sulcus) is the sulcus that divides the frontal and temporal lobes of the brain

Primary Auditory Cortex (A1)

the main area of cortex which first processes auditory information in the brain, situated on the inferior surface of the lateral sulcus

malleus

the malleus or hammer is a hammer-shaped small bone or ossicle of the middle ear which connects with the incus and is attached to the inner surface of the eardrum

Superior Temporal Gyrus

the most superior gyrus in the temporal lobe, situated just below the lateral sulcus, on which is much of auditory cortex

Superior Temporal Sulcus

the most superior sulcus in the temporal lobe, situated just below the superior temporal gyrus

Organ of Corti

the organ of Corti is the organ of the inner ear of mammals that contains the hair cells (the auditory sensory cells)

ossicles

the ossicles (also called auditory ossicles) are the three smallest bones in the human body. They are contained within the middle ear space and serve to transmit sounds from the air to the fluid-filled cochlea. The absence of the auditory ossicles would constitute a moderate-to-severe hearing loss

Oval Window

the oval window is a membrane-covered opening which leads from the middle ear to the vestibule of the inner ear

Hair Cells

the sensory receptors of the auditory system located on the basilar membrane in the cochlea that convert sound waves to nerve signals by having their hair-like stereocilia being physically moved by sound waves in the cochlear fluid

Stapes

the stapes or stirrup is the stirrup-shaped small bone or ossicle in the middle ear which is attached to the incus and oval window

Tympanic Membrane

the tympanic membrane is a thin membrane that separates the external ear from the middle ear whose function is to transmit sound from the air to the ossicles inside the middle ear

Tonotopic Gradient

tones close to each other in terms of frequency are represented in topologically neighboring neurons in auditory cortex

Sensorineural Hearing Loss

Hearing loss caused by damage to the sensory cells and/or nerve fibers of the vestibulocochlear nerve (auditory nerve/Cranial nerve VIII), the inner ear, or central processing centers of the brain. Seen in many forms of congenital and acquired deafness

Superior Olive

a small body in the mid-pons section of the brainstem involved in the localization of sound by determining differences in the intensity and timing of neural responses from each ear for a particular sound

Otosclerosis

abnormal growth of bone of the middle ear which can result in hearing loss. Seen in .5%-10% of population, usually starts in middle age. Exact cause is unclear-genetic factors play a role, viruses like measles may be involved as well. Treated with hearing aids and/or surgery to remove the stapes

Auditory Field Map

cortical area consisting of one tonotopic gradient and one perpendicular periodotopic gradient

Conductive Hearing Loss

mechanical hearing loss, resulting from blockage in the ear canal, a ruptured eardrum, or restriction of the movement of tiny bones in the middle ear, which prevents sound vibrations being transferred to the cochlea. Seen in otosclerosis