Valentina Moro, Cosimo Urgesi, Simone Pernigo, Paola Lanteri,
Mariella Pazzaglia, and Salvatore Maria Aglioti
1. Single unit recording and fMRI in monkeys
2. Intracranial recordings in humans
3. Evoked potentials in humans
4. fMRI in humans
5. TMS in humans
6. Lesions in humans – this experiment
Neurons in inferior temporal cortex (IT) respond selectively to human/monkey bodies
and body parts. Other neurons in IT respond selectively to faces but not to hands.
from Peelem & Downing, 2007
‫שיטות‬
Extrastriate visual cortex
N230 - hand selective
from Peelem & Downing, 2007
‫שיטות‬
N170 (face selective) and N190 (body selective) have distinct lateral occipitotemporal
Sources (according to source localization)
from Peelem & Downing, 2007
‫שיטות‬
Extrastriate body area (EBA) - posterior inferior temporal sulcus/middle temporal gyrus
- Body parts.
Fusiform body area (FBA) – Whole bodies.
from Peelem & Downing, 2007
‫שיטות‬
EBA - 150–250 ms after stimulus onset - impaired performance on a delayed
match-to-sample task involving images of body parts, but not face or motorcycle parts.
Extrastriate body area (EBA)
Static bodies
Dynamic displays of bodies
Body parts
Body forms but not actions
Not faces
Fusiform body area (FBA)
Whole body
Body parts
Ventral Premotor cortex (vPMc)
Body actions but not form
‫שיטות‬
Patients with anterior (n=14) and posterior (n=14) lesions.
No visual agnosia
Study 1 – face parts vs. body parts vs. objects
Study 2 – Body Form vs. Body Action
Task: Two choice matching to sample visual discrimination
*In a separate experiment with controls: inverted and upright stimuli
inversion effect for faces only (configural processing for faces)
Group (anterior, posterior, control) X Category (body, face, object)
Posterior patients perform worse
than controls and anterior
patients in discriminating body
and face parts.
Body
Face
Relationship between injury and behavior on a voxel-by-voxel basis
In this experiment:
1. For each patient T1 weighted MRI
2. Each lesion was superimposed onto a standard brain
3. To identify the voxels that are associated with the three categories,
three VLSM analyses were conducted.
The predictors were:
% correct responses of the for body
% correct responses for face
% correct responses for object
(Individual % CR of each category were entered)
Impaired body discrimination – bilateral inferior and middle Occipitotmeporal &
left STS lesions.
EBA
FBA
Task: two choice matching to sample visual discrimination (action or form)
Form discrimination: Different models, same action
Action discrimination: Same model, different action.
Group (anterior, posterior, control) X Type (action, form)
Anterior patients – worse for actions
Posterior patients – worse for form /
identity
Double dissociation between action
& form and anterior posterior Independent from lateralization
Predictors:
% CR in Action/% CR in Form
% CR in Form/% CR in Action
Body form - Lateral occipitotemporal
(bilatetral) - (BA 19,37) – EBA
Left inferior occipital (BA 19).
same size & location as in study 1
Body action – left vPMC,
a little bit right as well.
Selective deficits for bodies at the perceptual level
Study 1: Body agnosia
1. Face & body - Ventromedial, occipitotemporal (FBA).
2. Body only - Extrastriate body area (EBA).
Study 2: body form and body action agnosias.
3. Double dissociation:
Body form - EBA & FBA
Body action - ventral premotor cortex (vPMc).
Selective deficits for bodies at the perceptual level
Neural substrates for form and body action agnosias that are
Double dissociated.
Left and right ventral premotor are causatively associates with
Action perception.
Diagnostic tools for clinical assessment.
1. We need sensitive tests (The Posterior patients did not report
having difficulties in recognizing bodies in daily life).
2. Body selective areas are small and sometimes overlap with object,
face and motion areas. Maybe motion agnosia masks body agnosia?
3. Body deficits may be compensated by other body selective areas
(ipsilateral or contralaetral)