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

from Peelem & Downing, 2007

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.

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Extrastriate visual cortexN230 - hand selective

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from Peelem & Downing, 2007

N170 (face selective) and N190 (body selective) have distinct lateral occipitotemporal Sources (according to source localization)

from Peelem & Downing, 2007

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Extrastriate body area (EBA) - posterior inferior temporal sulcus/middle temporal gyrus - Body parts.Fusiform body area (FBA) – Whole bodies.

from Peelem & Downing, 2007

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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 bodiesDynamic displays of bodiesBody partsBody forms but not actionsNot faces

Fusiform body area (FBA)Whole bodyBody parts

Ventral Premotor cortex (vPMc)Body actions but not form

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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)

FaceBody

Group (anterior, posterior, control) X Category (body, face, object)

Posterior patients perform worse than controls and anterior patients in discriminating body and face parts.

Relationship between injury and behavior on a voxel-by-voxel basisIn this experiment:

1. For each patient T1 weighted MRI2. Each lesion was superimposed onto a standard brain3. 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.

EBAFBA

Task: two choice matching to sample visual discrimination (action or form)

Form discrimination: Different models, same actionAction 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) – EBALeft inferior occipital (BA 19).same size & location as in study 1

Body action – left vPMC, a little bit right as well.

Study 1: Body agnosia1. Face & body - Ventromedial, occipitotemporal (FBA).

2. Body only - Extrastriate body area (EBA).

Selective deficits for bodies at the perceptual level

Study 2: body form and body action agnosias. 3. Double dissociation:

Body form - EBA & FBA Body action - ventral premotor cortex (vPMc).

Neural substrates for form and body action agnosias that areDouble dissociated.

Left and right ventral premotor are causatively associates withAction perception.

Diagnostic tools for clinical assessment.

Selective deficits for bodies at the perceptual level

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)