Value 0.001%

1
Relating imaging and patient studies of tool
processing J. Devlin1,2, C. Moore1, C. Mummery1,
J. Phillips1, M. Gorno-Tempini1, M. Rushworth1,2,
and C. Price1 1Wellcome Department of Cognitive
Neurology, Institute of Neurology 2Centre for
Functional Magnetic Resonance Imaging of the
Brain, University of Oxford
Results (cont.)
Summary of results
Background

• First study to demonstrate LPMT activation for
  tools relative to living things at a corrected
  level of significance. May be due to
• Small effect sizes (lt3 rCBF) and
• Context-specific effects, i.e. category effects
  were only present in tasks required semantic
  processing
• Results consistent with previous imaging studies
  showing Tools gt Animals in ventral pre-motor
  cortex BUT also demonstrated that this effect was
  not present relative to fruit
• No area was activated only by tools

Several functional neuroimaging studies have
reported a region in the left posterior middle
temporal cortex that is more active when words
and pictures represent tools than other
categories of objects (see Fig. 1 and ref. 14 for
a review). This area is not damaged, however, by
fronto-parietal lesions typically associated with
selective deficits for man-made items4. The
lesion data is more consistent with the few
imaging studies that have reported increased left
pre-motor activation for tools2, 7, 9.
Figure 3 Effect sizes for tools
1. L. post. Middle temproal gyrus
3. L. anterior supramarginal gyrus
4 3 2 1 0 -1
rCBF change
W B B W B W P P
1 2 3 4 5 6 7 8
Figure 1 Tools activate LPMT
1 2 3 4 5 6 7 8
2. L. ventral pre-motor area
Contrasts 1. Syllable decisions12 2.
Screen size decisions13 3. Semantic
decisions13 4. Semantic decisions12 5. W-P
matching10 6. Category fluency11 7. Naming
pictures6 8. Naming pictures10
4 3 2 1 0 -1
Value 0.001
rCBF change
Discussion
W B B W B W P P

• These findings correspond well with the
  neurophysiological literature showing that in
  monkeys neurons in the ventral pre-motor area F5
  respond to visually presented graspable objects
  such as tools and fruit5, 8.
• This region is part of a visuo-action network
  including pre-motor (F5), anterior intra-parietal
  (AIP/7b), and inferior bank of the superior
  temporal sulcus (STS) regions (see Fig. 4)

1 2 3 4 5 6 7 8
Activation in the left posterior middle temporal
cortex (LPMT) and left pre-motor area in normals
in a picture naming task from (Martin et al.
1996)
Key
Phonological tasks W Words Perceptual
tasks P Pictures Semantic decision tasks B Both
words and Word retrieval tasks pictures
Current Study

• Tasks without a strong semantic component (e.g.
  screen size decisions and syllable decisions) did
  not show a consistent advantage for tools
• More semantic tasks, on the other hand, such as
  semantic decisions and picture naming, revealed
  small ( lt3 rCBF changes) but consistent effects
  for tools gt living things

• The current study investigated tool-associated
  brain activations in an attempt to reconcile the
  apparent discrepancies between the imaging and
  lesion literature.
• Data from 50 subjects performing 6 experiments
  were acquired on a single PET scanner (see Table)
• Single multi-factorial analysis with three
  factors
• 1) Category (natural vs. man-made)
• 2) Task
• 3) Stimulus type
• Man-made items divided in tools and non-tools.

Figure 4 Macaque visuo-action network
Q Were these activations truly category-specific?
Key A Animals
Fr Fruit BP Body parts T Tools Fa Famous
Faces V Vehicles FF False fonts
Adopted from Jeannerod et al. (1995)
Table

• The three regions identified in the current study
  may be homologues of this visuo-action network.
• The same regions often activated in human imaging
  studies of grasping or hand movements1,3
• These results provide a plausible explanation for
  patients with semantic impairments to man-made
  items who typically have large left
  fronto-parietal lesions
• ? Although the LPMT is spared, the lesion can
  affect the inferior parietal and ventral
  pre-motor regions and the connections between
  them.

1. L. posterior middle temporal area?
Word-picture matching10
Picture naming10
Picture naming6
Relative effect sizes
A Fr V T FF
Fa A T BP
A Fr V T MN SN
? Tools (T), simple non-objects (SN) and body
parts (BP) all activated the LPMT.
Results

• Tools relative to living things activated three
  regions in the left hemisphere (see Fig. 2)
• 1. Posterior middle temporal cortex (LPMT)
• 2. Ventral pre-motor cortex
• 3. Anterior supramarginal gyrus
• but only for tasks with a strong semantic
  component (see Fig. 3)

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2. L. ventral pre-motor area?
Word-picture matching10
Picture naming10
Key A Animals FF False fonts Fr Fruit
T Tools V Vehicles
Relative effect sizes
A Fr V T FF
A Fr V T
Figure 2 Tools gt Living thingsfor semantic
tasks only
? Fruit (Fr) and tools (T) both activate the
ventral pre-motor region.
3. L. anterior supramarginal area?
Word-picture matching10
Picture naming10
L
R
L
R
L
R
Key A Animals FF False fonts Fr Fruit
T Tools V Vehicles
Relative effect sizes
L. posterior middle temporal cortex (-62, -58,
0) SPMZ5.3 plt0.005 corrected
L. ventral pre-motor (-42, 4, 18) SPMZ3.6 plt0.0
01 uncorrected
L. anterior supramarginal (-60, -24,
34) SPMZ3.8 plt0.001 uncorrected
A Fr V T FF
A Fr V T
? Tools (T) and false fonts (FF) activated the
anterior supramarginal region.