W2L2 - Neural mechanisms of face perception in humans and non-humans Flashcards
Evidence for face neurons from human adaptation
- Faces show adaptation
- Like Neurons
- Bistable perception in semi-upright
- See one face then the other
- Suggest neurons adapted to see one face than the otehr
What are the 3 studies of neural mechanism of face-processing in non-human primates
- Single Cell
- fMRI
- Microstimulation
Non-Human Primate Study (1): Single Cell Study in face-processing in non-human primates
- Non-human primate has face neurons
- Face cells in IT (fusiform gyrus) responded to an intact face
- Not selective for individual features presented in isolation
Non-Human Primate Study (2) :fMRI study in face-processing in non-human primates (READING)
- Identified “Face Area” using fMRI
- In temporal lobe
- Recorded 400 cells in “Face Area”
- 97% of visual cells responded exclusively to faces.
- Apple and clock showed some response (roundness? property of faces?)
Non-Human Primate Study (3): Micro-stimulation in face-processing in non-human primates. Methods and Results
Is IT (Fusiform Gyrus) a face perception area?
- Stimulated neurons in IT and influence face/flower perception
Results
1.) Stiimulation
- Especially 50-100ms
- Higher likelihood to see faces at all levels of noise
No stimulation
-
Equal probability to see face/flower
2. ) Stimulation effect greatest for face-sensitive cells within IT
What are the human physiological evidences for specialised facial pathways
- ) MEG
- ) fMRI
- ) ECoG
- ) Stimulation
Human Study (1): MEG Study for face-perception in humans neural.
MEG (Cross of EEG and fMRI)
- Temporal responses for faces consistently higher M170 compared to cars and shoes
- No difference between novices and experts
- Suggesting signal for faces
Human Study (2): fMRI Study for face-perception in humans neural.
Manipulaed parts and configuration of faces and houses.
FFA
- Faces have bigger respones than houses, hands, two-tone-faces
- Does not depend on changing spaces or parts
- Sensitivity to faces
LOC (Lateral Occipital)
- Bigger reponse to changes in Parts
- No difference for faces or house
- Insensitive to identity
- Senstivity to whether 2 images are the same
Human Study (2.5) fMRI Study for face-perception in humans neural. What happens to bistable stimuli and FFA
For bistable stimuli, the FFA responds more strongly when subjects perceive a face than when they do not
- Suggests FFA is activated specifically by whole faces, not by low-level stimulus features that comprise faces
What are neural evidence (not greebles) to suggest FFA is related to level of expertise
- Car expert no centre of right FFA (subset of FFA) for bird object
- Bird expert no centre of right FFA (subset of FFA) for car object
Why are cars, birds, dogs criticized for using as expert for face-perception? (What are face-like properties)
They do not have face-like properties
- Similar features arranged in similar configurations
- Recognition at subordinate level
- Stimuli for which participants are experts
What happens when greebles become experts in FFA vs novices
- FFA fMRI response change
- Part whole effect (for upright)
- Greeble expert recognition behaviour and physiology consistent with that found for faces
- Configural effects not present in novice data
Comparative fMRI: Human v Macaque
Activate the same areas
Face Perception: 8 Epilepsy Faces Single Units
- Single units responded not only to faces, but familiar faces such as Halle Barry
- Not only face information, but person-identity units
Human Study (3) Face Perception: fMRI + ECoG
- Category-selective response in ventral temporal cortex (VTC)
- High Frequency Broadband (30-160HZ) [only high]
- Strong positive correlation between fMRI and ECoG signal in HFB
- Spatial coupling was tighter for face-selectivity than house selectivity
Note: HFB
