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Mar 19, 2023 206 likes •327 views

Face and Word Processing: Domain-specific cortical areas Two Sides of the Same Brain Fusiform Face Area (FFA) Visual Word-Form Area (VWFA) David C. Plaut Parahippocampal Place Area (PPA) Marlene Behrmann Extrastriate Body Area

SLIDE 1

Face and Word Processing:

Two Sides of the Same Brain

David C. Plaut Marlene Behrmann

Department of Psychology Carnegie Mellon University Center for the Neural Basis of Cognition

Domain-specific cortical areas

 Fusiform Face Area (FFA)  Visual Word-Form Area (VWFA)  Parahippocampal Place Area (PPA)  Extrastriate Body Area (EBA)  Fusiform Body Area (FBA)

Faces and words Bilateral homologous activation

Malach et al. Cohen et al. 2004

TREE vs. /tri:/

x= 40, y= –55, z= –10

R L R L

x= –42, y= –57, z= –15

FFA VWFA

N170 waveform specific to faces

Carmel et al. (2002)

SLIDE 2

N170 waveform for letter strings

Bentin et al. (1999)

Faces and words: ERP

L R L R L R

Rossion et al. (2003)

Maturation of FFA

Scherf et al. (2007)

Lesions to FFA

 Prosopagnosia

− Visual recognition much poorer for faces vs. other

bjects

− Can be bilateral but right lesion suffices − Rely on other cues for recognition

R R R

SLIDE 3

Lesions to VWFA

 Pure alexia

− Impairment in word recognition in premorbidly literate adults − Left occipitotemporal lesion − No general language impairment − Rely on sequential “letter-by-letter” strategy

FFA adjacent to central visual information

Levy et al. (2001), Malach et al. (2002)

Faces, words and eccentricity

Hasson et al. (2003)

Hemispheric model

SLIDE 4

Faces Houses Words

SLIDE 5

central peripheral central peripheral

X-Y coordinates Polar coordinates

Scale variation Acquisition

Central vision

Receptive/ projective fields

SLIDE 6

Peripheral vision

Receptive/ projective fields

 For each horizontal

position (central to peripheral) in each hemisphere, remove three adjacent columns

f intermediate

(fusiform) units

 Measure recognition

performance on faces and houses (across all scales)

Lesioning method

SLIDE 7

Predictions

 Domain generality

− Ventral temporal-occipital cortex involved in any fine-

grained visual discrimination

 Bilateral participation

− Unilateral lesions impact both faces and words

 Competition for representation

− Degree of face and word specialization related within

individuals

Domain generality

Pure alexia

Same-different matching

Linear effect of visual complexity

Visual Complexity Reaction Time (ms)

SLIDE 8

Bilateral participation

Predicted extent of impairment

Faces Words Prosop. Controls Alexia

Words: Lexical decision

RT

Face discrimination (errors): Controls < Alexia < Prosop.

% Errors

Competition for representation

within-field between-field

Match-to-sample task: words or faces

SLIDE 9

Left-field advantage for faces Right-field advantage for words Individual distribution

Compare magnitudes of within-field advantage for faces (left field) vs. words (right field)

Correlation

SLIDE 10

Conclusions

 Distributed cortical network for faces and words

− Different representations, similar computations

 Reliance on high visual acuity

− Fine-grained discriminations

 Topographic constraints on learning

− Bias for local connectivity

 Graded functional specialization

− Both within and between hemispheres