1. Combining methods in Cognitive Neuroscience Flashcards
Pitcher et al (2009) Comparing:
- Occipital Face Area (OFA)
- Lateral Occipital area (LO - objects)
- Extrastriate Body Area (EBA)
Disrupting area we are interested in for as long as the second stimulus is on the screen
- ## The task is to determine whether the first and second stimuli are the sameFaces & Objects:
- Subject got significantly worse at matching faces when rOFA stimulated compared to when rLO stimulated
- ## Similarly, subjects got significantly worse at matching objects when rLO stimulated compared to when rOFA stimulatedObjects & Bodies/Faces & Bodies:
- Same pattern
!Very selective effect of TMS on each area:
- Triple dissociation of faces, bodies and objects
- TMS can selectively disrupt a targeted ROI of approx 1-2cm in size
Pitcher, Holiday & Ungerleider:
Disrupting memory of stimuli using TMS
What happens if we disrupt visual working memory?
- Disrupting the presentation of the face that is held in WM for 4seconds (at different time points in the retention period)
Disrupting area we are interested in at different points during 4s retention period before the second face is on the screen
- ## The task is to determine whether the first and second face are the sameTMS delivered rOFA only at 50ms after stimulus offset disrupts visual working memory compared to control (LO)
What is the face specific ERP?
N170 (Negative peak, at around 170ms)
The OFA (Occipital Face Area) responds to
- Faces / facial features
- expression recognition
The pSTS (posterior Superior Temporal Sulcus) responds to
- Likes facial parts that move
- Responds to facial expressions
Pitcher et al (2008)
When does facial stimulus information reach:
- Occipital Face Area (OFA)
and - Right Somatosensory Cortex
One facial expression shown, then a second expression shown (during display of second face, a double pulse TMS is applied at various intervals)
Task = are the two the same?
- OFA = Lower accuracy due to TMS at 60&100ms
- Right Somatosensory Cortex = Lower accuracy due to TMS at 100&170ms
(!!!Impaired before 170ms, NOT at 170ms)
Pitcher (2014)
When does facial stimulus information reach:
- Right Occipital Face Area (OFA)
and - Right Posterior Superior Temporal Sulcus (pSTS)
One facial expression shown, then a second expression shown (during display of second face, a double pulse TMS is applied at various intervals)
Task = are the two the same?
- rOFA = Lower accuracy due to TMS at 60&100ms
- rSTS = Lower accuracy due to TMS at 60&140
(!!!Impaired before 170ms)
Afraz et al. (2006):
Timing of EEG and TMS
Monkeys presented with face stimuli resulting in an N170 ERP peak response (which starts around 100ms)
TMS applied at 50-100ms has the greatest disruptive effect
!ERP is recording the activity that has already happened
!TMS is interrupting activity that is about to happen
Pitcher et al (2011):
fMRI activity in response to static/moving(dynamic):
- !Faces
- !Bodies
- Controls
Across different ROIs:
- rFFA
- rOFA (occipital face area)
- rpSTS (right posterior Superior Temporal Sulcus)
- rFFA = No difference in activation by static and moving faces/bodies
- rOFA = No difference in activation by static and moving faces/bodies
- rpSTS = Response to moving faces is 3x higher compared to static /// same effect for bodies
!rpSTS is very responsive to moving bodies and faces
Pitcher, Duchaine & Walsh:
fMRI & TMS
fMRI activity in response to static/dynamic:
- Faces
- Objects
In these areas (TMS vs Baseline):
- rOFA (right Occipital Face Area)
- rpSTS (right posterior Superior Temporal Sulcus)
Applying Theta burst TMS (lasting ~30min) to create “lesions” before fMRI
- Thetaburst TMS over OFA reduced the neural response to STATIC faces in pSTS
- Thetaburst TMS over pSTS reduced the neural response to DYNAMIC faces in pSTS
-------------------------------- Expression recognition (dynamic) vs identity recognition (static)
- !pSTS cares only about dynamic faces
- !OFA and FFA sensitive to both static and dynamic faces
What is an acquired prosopagnosic?
- face blindness
- resulting from stroke or close head injury
Rezlescu et al (2012):
Herschel is an acquired prosopagnosic missing the right Occipital Face Area (rOFA) which is thought to be where information about faces has to go through first
- However, the rpSTS (right posterior Superior Temporal Sulcus) is intact. This area is very active when looking at moving faces…
Other areas responsive to faces are inactive:
- (Damaged)rOFA
- FFA
However, rpSTS is very active when viewing moving faces
!Even thought there is an impaired response in rOFA and FFA there is an entirely typical response to moving faces in rpSTS
!There must be another input to the rpSTS
!Herschel has a normal response to moving dots in the V5/MT responsible for all visual motion
!Main input to rpSTS could be the V5/MT (an intact pathway!)
Which of the following brain areas doesn’t show a greater response to faces than places in an fMRI experiment of face perception?
A Superior temporal sulcus B Lateral occipital cortex C Fusiform gyrus D Parahippocampal Gyrus E Amygdala
E: Amygdala
Thetaburst TMS reduces the BOLD response for faces when delivered over the posterior STS.
How long does the reduction effect last?
30 minutes
According to Haxby et al.’s (2000) model of the core neural system involved in face perception, damage to the superior temporal sulcus will cause problems in:
Recognising facial expressions
