Sensory System Interaction Flashcards
What is sound localisation?
The listeners ability to identify the location or origin of a detected sound in direction and distance
What are the benefits of sound localisation?
Knowing exactly where a sound is can help with your movements and can improve your speech understanding
What are the two forms of cues for sound localisation?
Monaural and binaural cues
What are monaural cues?
Used to localise sound in the vertical axis
What are head related transfer functions?
A response that characterises how the ear receives a sound from a point in space
What are binaural cues?
Sound position in the horizontal plane
What are interaural timing differences?
The difference in the arrival time of sound at the two ears
What are interaural level differences?
The difference in the frequency of sound at the two ears
In the LSO binural E1 pathway, if sound were to come in through the left ear, where would you get a high excitatory effect and where would you get a low excitatory effect?
You would get a high excitatory effect on the MNTB from the right aVCN and a low excitatory effect on the LSO from the left aVCN
What are ILDs encoded by in the LSO?
Cells that compare the incidence of excitatory ipsilateral and inhibitory contralateral inputs
What do the LSOs act as in the EI pathway?
Broad hemispheric channels
What is the overall position of a sound encoded by in the E1 pathway?
The balance of the average output at the two LSO channels
Describe the binaural EE pathway in birds
Occurs in the Nucleus Laminaris (NL), different locations of sound lead to different neurons in the NL being activated and therefore leading to an oscillatory pattern in the readings
What are ITDs encoded by in birds?
Cells that compare the coincidence of the excitatory ipsilateral and the excitatory contralateral inputs
How is the overall position of sound encoded?
By the particular channel activated
What sound frequency is the EE pathway in birds mainly for?
Low frequency
Describe the binaural EE pathway in mammals?
aVCNs from the left and right ear both synapse onto the MSO and provide excitatory inputs, low output on the side that sound is coming from
What are ITDs encoded by in the MSO?
Cells in the MSO that compare the coincidence of excitatory ipsilateral and excitatory contralateral inputs
What do the two MSOs act as in the EE pathway?
Broad hemispheric channels tuned to sounds from the opposite hemisphere
How is the overall position of a sound encoded in the EE pathway in mammals?
By the average population of response of the two MSO channels
What frequency of sound is the EE pathway in mammals mainly for?
Low frequency
Why is sensory interaction important?
Our ability to perceive objects requires multi sensory input. Improves precision, discrimination and speed of perception, improving reaction, selective attention and motor output
What do prisms do?
They affect the flow of information into the midbrain auditory localisation pathway
What is the normal pathway before prisms?
ITDs are mapped to form layers in the ICC
These layers converge to form a space map in the ICX
The auditory map in the ICX is aligned to the visual map in the OT with interactions from the CT
What is the pathway after prisms?
Instructions from the OT realign the ICX to match
What is the McGurk Effect an example of?
Auditory and visual interaction
What are the four parts of the cocktail party effect?
- Active sensing
- Selective attention
- Stimulus driven entertainment
- Cross-modal predictive cues
Describe active sensing
Motor and visual systems scan the scene. Fixations enable phase resetting of brain oscillations
Describe selective attention
PR synchronises the oscillatory activity in the appropriate sensory areas
Describe stimulus driven entertainment
Visual cues and the auditory wave front fine-tune the entertainment to the attended speech stream in the auditory cortex
Describe cross-modal predictive cues
Facial articulation and head movements precede speech. Auditory systems can anticipate what is coming. Enhanced tracking of the auditory stream from visual predictions
How does brain activity in supertaskers differ?
Brain activity in reduced. Higher neural efficiency that leads to better performance at a lower activity
