Auditory perception Flashcards
where is the primary auditory cortex/PAC/A1 located?
superior temporal gyrus, Heschl’s gyrus
how is PAC organised?
tonotopically; tones close to each other in frequencies
what is job of PAC?
1) segregate auditory objects
2) identify the location of sound in space
what is in the cochlea?
receives auditory input
has different receptors that are selectively tuned to different frequencies
carries sound right up to PAC
what is the PAC comprised ?
A1 is comprised of a core area
surrounded by the temporal lobe and angular gyrus
what is the cortical arrangement of A1?
tonotopically arranged; striped arrangements of binarual inputs, containing EE and EI cells that help with the localisation of sound
what are EE cells?
EE cells are contained within the stripes in A1
neurons in one stripe that are excited by both ears are EE cells
what are EI cells?
EI cells are contained within the stripes in A1
neurons in the next stripe that are excited by one ear, and exhibited by the other ear are EI cells
what do EE and EI cells do?
EE/EI cells alternating the auditory inputs are reminiscent of the ocular dominance in columns of V1 in visual system.
characteristics of PAC/A1?
- activation of PAC in response to various sound freqs
- precise tonotopic map of cochlea
- information from ears is projected bilaterally to A1
- ipsilateral/input from the same side of ear to A1 is weaker than contralateral
characteristics of A2/ secondary auditory cortex
-belt region surrounding A1 is A2..A2=parabelt regions
-A2 responds in a more diffused way to inputs in thalamus, less precise tonotopic organisation
…sorts out sound in a more meaningful way way, ie. perception.
-hierarchy when sounds are processed, A2 merges the complex sounds that A1 does not prefer. merges the frequencies together.
Petkov and Kayser, 2006? monkey auditory cortex
map of PCA is more complicated
- 3 fields of PAC:
1) prefers tones
2) surrounded by 8 neighbouring belts of A2
is fMRI a good measure of auditory activation?
fMRI is a poxy measure of neural processing in brain, its is not a direct measure
- fMRI measures blood flow to active regions of brain; we don’t have a high level of specificity in brain with fMRI
Okada 2010? sentences and intelligibility
sentences render greater sensitivity in intelligibility of speech
- pSTS/ posterior superior temporal sulcus responds to the meaning of sounds (Wernicke’s area)
- if played a sentence backwards, activation of pSTS is significantly reduced
- pSTS only cares about the intelligibility of speech
Rauschecker and Tias, 2000? functional task-specificity of A1
evidence that A1 is functionally separated according to task
the brain separates info and allows efficient sharing of task relevant information.
-study found that there are 2 processing systems in A1:
1) spatial stream, found in caudal part of superior temporal gyrus..projects to parietal cortex (similar to cortical visual pathway of object orientation i parietal cortex)
2) object/pattern stream, found in the anterior portions of the lateral belt/ anteriolateral area
Alain, 2001? what and where of auditory brain
-pitch processing rendered greater activation of auditory cortex in the inferior frontal gyrus
-identifying location of sounds rendered greater activation of posterior parietal cortex
…there are specialised auditory streams, the ‘what’(pitch) and the ‘where’…exact same as vis system
Clarke, 2002? patient studies
-JG had a lesion to temporal lobe, and had poor sound recognition
-ES had a lesion to parietal lobe, and had poor sound localisation
…functionally separate pathways that deal with diff types of tasks
Formisano, 2008? speaker identity and component identification
- found separate regions of brain that respond to speaker identity and component identification
…same as vis system, content of speech vs. who is speaking?
study on damage to auditory system?
auditory aphasia= lesion to A1, renders cortically deaf
- bilaterally lesioned PAC-show no awareness of sound, but better than chance in identifying the orientation of sound…residual functioning of A1 despite damage
- lesion to one side of A1 renders in tact discrimination of sound frequencies, but poor localisation of sound on contralateral side
what are Broca’s and Wernicke’s areas?
Broca’s area is about the physical speaking of language
- broca’s aphasia= speech is laboured and slow, non-fluent. affects written and oral speehc
- singing is more fluent in broca’s aphasia…singing might be separated from voice or speech processing
Wernicke’s area is about understanding language
- Wernicke’s aphasia= language understanding is impaired, spoken language is normal!
Cathy Price, 2012? functional areas in language processing
Broca’s area associated with pOp
Wernicke’s areas associated with pSTS
…both involved in perception and production of familiar stimuli
wernicke’s areas in temporal hemisphere, lies within A2 and is critical to understanding language comprehension
Hiokok and Poeppel, 2007? anatomy of language processing
-speech production found on dorsal paths, maps sensory representations onto motor representations
…action plans with speech, how can we articulate speech by using facial, mouth and oral movements of that sound
- speech perception found on ventral paths, maps sensory representations onto lexical conceptual meaning
- in speech production: Wernicke’s area (understanding speech) projects to Broca’s (speech production)
Ghazanfar and Hauser, 2001? sound perc in other species
specialised processing of auditory syst in other species, species-specific vocalisations
Lavan, 2017? laughing/ perc of other human vocalisations
laughs send out a social signal; can brain tell diff between polite (volitional)laughing and spontaneous laughing?..can we register authenticity of laughs?
- linear increases in responses in Heschl’s gyrus and superior temporal gyrus (STG) in authentic laughing
- linear relationship between arousal, valence and authenticity