L14- interaction btw perception and action Flashcards
re-excitation AKA reactivation
encoding required = first excitation
retrieval required second excitation.
reactivation -
- give cue
auditory recalls better with sound cue than visual
fusiform face area recalls better with pic than with sound.
- more recall - area of brain relating to that mode of perception needed.
common area for encoding and retrieval
though hippocampus - but maybe not.
seems as tho perceptual areas invovled with encoding and retrieval
nyberg - explicit memory of actions
motor cortex reactivated when recalling memory/action.
geng - saccades to remember location
fixate, target in spot. when disappears move eyes to it.
- reactive retinotopic visual cortex.
skinner -FFA
FFA reactivation during recall of faces
patient DF - what happened?
- cortical damage?
symptoms?
hypoxia from CO poisoning
- large lesions in ventrolateral occipital region, sparing v1.
- lesions: r/l lateral occipital cortex = LOC, ventral. left anterior parietal lobe.
visual form agnosia = problem recognizing object form. missing wholistic form.can draw from memory. orientations of hand - vision for action is intact.
optic ataxia patient RV
- dorsal stream, posterior parietal lesion.
poor visual motor transformation. good at perception of target & object.
– better at copying, but motor planning absent. cant estimate finger grasp.
RV vs DF
- ID objects as same/diff
- interact w object
- RV»_space; DF for naming.
- DF»_space;> RV for gripping. RV does random, incorrect.
perception ? Action?
- vvisual form agnosia
- optic ataxia
vfa; no perception, yes action = ventral damage
oa: yes perception, no action = dorsal stream
ventral stream damage
visual form agnosia
dorsal damage
optic ataxia
effects on delay on grip scaling
actions that require memory.
- need to use memory to remember object. slow arm movement, open hand wide, earlier. but still difference in grip between two object.
area used for object grasping?
AIP =dorsal.
area used for recognition
LOC = ventral
brain areas - activity for grasping/reaching and intact/scrambled
AIP - more active for grasping than reaching.
AIP - no difference in perception of intact vs scrambled.
LOC - same activtiy for reaching/grasping.
LOC - more activtiy for recognizing intact object than scrambled.
DF - delayed grasping
- immediately - quite accurate at grasping
- delay, can no longer grasp properly because image not on retina. - memory system needs to be activated.
DF doesnt have LOC, cant remember - so does LOC store info?
AIP store info? brain activity during action task
- see image, delay in dark, reach in dark.
see image = brain peaks
delay - moderately active brain. peaks again when touch.
grasping/reaching in fMRI
audio - told action. 18 sec delay. told - go/ignore. 18 sec
why 18 sec delay?
because of slow hemodynamic delay of BOLD signal
2 tasks done to ID 2 areas of interest
- grabbing vs reaching
- object vs scrambled
- frontal area & more posterior to visualize LOC
Left and right AIP showed what?
more grasp than reach response.
activation stays high during delay - same level during delay for both conditions.
more selectivity/activtiy for grasping than reaching.
left LOC - what is shown?
no activation over delay
- but can “see” thing in the dark. brain is coding for that spot in visual space even during the dark.
conjunction test in brain areas activated for both tasks
- doesnt care about memory delay. cares about what task - more activation for richer object recognition.
calcarine sulcus
- retinotopic mapping in the dark
v1 shows activation. greater for grasp than reach.
shows visual system can act in dark. not seeing, but trying to remember the space, activates it. proof that sensory areas are responsible for encoding and retrievall
- all objects reached for in lower vf, reactivation in upper vf = consistent. but, reactivation has that spatial info encoded.
vision phase grasping vs reaching
dorsal premotor area - similar to what’s in AIP.
there is memory maintenance in dPMa but no preference for reach/grasp
SMA - vision, action, delay.
preSMA = largest visual response
ant - midpoint
post SMA = smallest visual response
summary
LOC EarlyVisualC actviated during VS and reactivated in darkn
- reactivation may reflect retrieval of object features from memory
- areas involved in recognition & vision re-recruited to provide info to dorsal stream. = may reflect mental imagery and hand needed for action. consistent w DF. LOC reactivation for delayed grasping.
EVC show crude retinotopic reactivation
delay activity observed in dorsal stram: AIP, SMA, dorsalPM, M1.
more grasping than reacing = more detailed features required for grasping.
