PSYC 212 - Midterm 2, Brain areas & Ear

Auditory Canal

how sound enters the ear, directs sound waves from the outer ear to the eardrum  

Tympanic Membrane

when sound hits it, it vibrates at the same frequency – is a thin membrane that separates outer and middle ear, transmits vibrations to ossicles

Ossicles

three small bones in middle ear (malleus (hammer), incus (anvil) and stapes) that amplify and transmit vibrations to inner ear

Tensor tympani muscle

muscle that can block auditory tube, reflex to contract and block hearing if sound is too loud 

Cochlea

spiral-shaped, fluid-filled, inner ear – converts sound vibrations into neural signals for hearing  

Oval window

membrane-covered opening connecting middle ear and cochlea, transmits vibrations from ossicles  

Round window

flexible membrane in cochlea, refleives pressure from soundwaves in fluid

Cochlear nerve

nerve carrying auditory info to brain 

Organ of Corti

structure on the basilar membrane of the cochlea, made up of haircells and dendrites of auditory nerve fibres 

Basilar membrane

structure in cochlea that vibrates in response to sound, its hair cells play a key role in frequency discrimination  

Tectorial membrane

gelatinous membrane in cochlea, interacts with hair cells, aids with conversion of mechanical sound vibrations into electrical signals  

Hair cells

sensory receptor cells in cochlea that detect sound vibrations and convert them to neural signals 

How do hair cells transduce sound?

• Tip of hair cells have plugs connected by string to eachother, at rest all potassium channels are closed – upright at rest  

• When sound causes cochlea liquid to move which tips hair cells, unplugging the potassium channel, leading to action potential firing 

Describe Cochlear place code  

Back of the ear, cochlear apex suited for low frequency  

Start of the cochlear, cochlear base suited for high frequency 

Describe the where/dorsal pathway

Spatial awareness

• Processes locations and shapes of objects  

• Does not encode object names or functions 

• Extends from occipital lobe to the parietal lobe

Describe the what/ventral pathway

object recognition, V1 to V4 

• Processes object identity, names, and functions, independent to location 

• Extends from occipital lobe to temporal lobe 

What is processed in the Posterior IT?

starts combining parts of objects, not necessarily responding to whole objects yet