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Julia Robotham1, Sheila Kerry2, Grace Rice3, Alex Leff2, Matt Lambon-Ralph3 & Randi Starrfelt1
1Department of Psychology, University of Copenhagen
2Institute of Cognitive Neuroscience, University College London
3The Neuroscience and Aphasia Research Unit (NARU), University of Manchester
Say hello to BoB
Introducing the Back of the Brain Project
Left hemisphere Right hemisphere
Background
Face and words recognition has traditionally been thought to
rely on highly specialised and relatively independent cognitive
processes.
Strong evidence for this has come from single case studies of
patients with:
•pure prosopagnosia: a selective face recognition deficit
•pure alexia: a selective word recognition deficit
Recent theories, such as the many-to-many hypothesis
(Behrmann & Plaut, 2013), suggest instead that the cognitive
and cerebral processes underlying visual recognition are
more distributed and interactive.
While single case studies are well suited to investigate
dissociations between deficits, larger groups of patients are
needed to investigate associations predicted by a distributed
model.
International collaboration
Study design University of Copenhagen
•Prof. Randi Starrfelt
•Ph.d. student: Julia Ro Robotham
Patient/control
recruitment
and assessment
University College London
•Prof. Alex Leff
•Postdoc: Sheila Kerry
University of Manchester
•Prof. Matt Lambon-Ralph
•Postdoc: Grace Rice
What’s novel?
•Participants selected according to lesion localization, not according to symptoms Expecting
novel patterns of lesions and symptoms.
•All participants assessed with the same wide range of functions with sensitive tests Enabling
direct comparison across subjects, which is often not possible across single case studies.
•Tests of face, word and object processing: Same level of processing tested across stimulus type.
•Large group of PCA patients included.
Status
•25 patients tested (right lesions n = 6; left lesions n = 16; bilateral lesions n = 3)
•3 control participants tested
Handwriting
recognition
test
Topographical
disorientation:
The wayfinding
questionnaire
Semantic processes and
language
Word processing
- Neale: text reading
- Reading 3,5,7 letter words (RT)
- Reading regular, irregular and
non-words (RT)
- Letter, digit, and word naming: RT
- Single item report:: letters, digits
and words (short presentation)
- Lexical decision
- Surprise recognition task: words
- Delayed matching task: words
Object processing
- Picture naming
- Object categorization
- Object decision test: yes/no
- Cambridge house memory test
- Surprise recognition task: objects
- Delayed matching task: objects
Face processing
- Famous face naming
- Famous face familiarity test: yes/no
- Cambridge face memory test
- Surprise recognition task: faces
- Delayed matching task: faces
- Writing to dictation
- Semantics: Synonym judgement task
Intermediate and low-level
visual perception
Background information
IDENTIFICATION
RECOGNITION
- Intermediate visual perception: L-post
- Visual field test: Copenhagen perimetry
- Visual acuity: FrACT (Landolt C)
- Colour perception: D-15 test
- Contrast sensitivity: the functional acuity
contrast test
- Handedness: Edinburgh short-form (5 items)
- Depression: Geriatric depression scale: GDS-15
- Cognition: Oxford Cognitive Screen; Digit span (WASI): forwards and backwards
- Basic motor response time: Simple visual RT test (up vs down)
- Premorbid reading: Adult reading history questionnaire
- Premorbid face recognition: Faces and emotions questionnaire
Figure 1:
Behavioural
test battery
Methods
70-100 patients
(stroke in posterior
cerebral artery)
50 healthy controls
(matched as group for
age and education)
Behavioural tests
All patients are assessed (>9 months post-stroke) a
large battery of sensitive behavioural tests (see figure
1 for overview of functions assessed).
Assessment of each patient carried out over 3 days
(within maximum 3 weeks).
Imaging
•Structural T1 scan
•Functional localiser: faces and scrambled faces,
words and checkerboards
•Diffusion tensor imaging (DTI) scan
Aim of the study
The study aims to shed new light on the processes and
cerebral architecture underlying visual recognition of faces
and words.
Some of the core research questions:
•Do face and word processing rely on processes that are
largely independent or highly distributed and shared?
•What is the relationship between deficits in object, word or
face processing and lower-level and intermediate visual
perceptual deficits?
•Is there a relationship between premorbid reading skills and
type and severity of alexia and prosopagnosia following
stroke?
•How do visual field defects affect higher-level visual
perception?
•How are visual recognition and semantics related?
•Can reading be spared after a lesion in the left fusiform
gyrus and can face recognition be spared after a lesion in
the right fusiform gyrus?