L8 - interaction between different sensory systems Flashcards
binaural hearing
hear sounds with both ears know where sound is know direction predict where it moves next feel part of 3D world improves speech understanding
monoaural hearing
only hear from one side
don’t know exactly where sound is coming
what plane is sound elevation in
vertical plane
what plane is sound position in
horizontal position
sound elevation
monoaural cues
head related transfer functions
sound position
two binaural cues
spectral notches function
help to localise sounds in the vertical plane
precisely timed to the onset of sound bouncing of the folds of the outer ear
distorts /alters sound creating a specific patters
all ears are different shapes so spectral notches must be learned by individuals
what are IDLs
interaural level differences - difference in the intensity of sound at the two ears (mainly for high frequency sounds)
what are ITDs
intramural timing differences - where the brain compares the arrival times of sounds at both ears - as small as 10micro seconds (mainly for lower frequency sounds)
outline the auditory pathway
1) cochlea nucleus (DCN and VCN)
2) superior olivary complex (SOC)
3) inferior and superior colliculus
4) medial geniculate nucleus
5) Auditory complex
function of the cochlear nucleus
2 pathways
from VCN = sound localisation
from DCN = sound recognition
function of the superior olivary complex
sound localisation
function of the inferior and superior colliculus
integration with non-auditory input e.g. somatosensory and vision
function of the medial geniculate nucleus
involved in learning and memory
functions of the auditory complex
cognition, attention, memory, decision making
what happens as auditory signals go through the brain
they get more integrated with info from other sensory systems
outline the superior olivary complex in the brainstem
the nerve fibres from both ears enter the cochlear nucleus, the 1st nuclei in the CNS
neurons from the anterior ventral cochlear nucleus go. to the superior olivary complex which is composed of the lateral superior olive and medial superior olive and the medial nucleus of the trapezoid body
outline the detection of intramural level differences (IDLs)
The IDLs are detected by cells in the LSO called principle cells
The LSO cells receive one excitatory input from aVCN cells on the same side of the head (ipsilateral side of the head)
The same LSO cells receive an indirect ihibitory input from the contralateral side of the head
The inhibtory input, begins as an excitatory fibre from the aVCN, crosses the midline and synapses in the MNTB which forms an inhibitory synapse to the LSO
which type of input is received from the ipsilateral ear
excitatory
what type of input is received from the contralateral ear
inhibitory
which input is. larger ipsilateral or contralateral
ipsilateral
what is the overall position of sound encoded by
the balance in average output rate of the LSO channels
what are IDLs encoded by
cells in the LSO that compare the coincidence of excitatory ipsilateral and inhibitory contralateral inputs
outline the detection of ITDs
the binaural excitatory-excitatory (EE) pathway
ITDs are encoded by cells in the MSO that compare the coincidence of excitatory ipsilateral and contralateral inputs
the two MSOs acts as broad hemispheric channels tuned to sounds from the opposite hemisphere
the overall position of a sound is encoded by the balance between the average population response of the two MSO channels
mainly for LF hearing
