J. Devlin 1,2, C. Moore 1,3, C. Mummery 1, J. Phillips 1, M. Gorno-Tempini 1, U. Noppenney 1, K. Friston 1, R. Frackowiak 1, and C. Price 1 1 Wellcome Department of Cognitive Neurology 2 Functional Magnetic Resonance Imaging of the Brain 3 Institute of Psychiatry Is there an anatomical basis category specificity?

Cognitive theories of category specificity Semantic theories zEvolutionary account: Individual categories recruit distinct neural regions. (Caramazza & Shelton, 1998) zPerceptional/functional account: Perceptual and functional attributes localised in different regions. (Warrington & Shallice, 1984) zCognitive structure account: Undifferentiated semantic system at a neural level (Tyler et al., in press)

Cognitive theories and neuroimaging zAnatomical hypotheses can be best evaluated by functional neuroimaging, however, the findings to date are very variable yLiving things > man-made items -- only three areas identified in more than one study: 1) bilateral anterior temporal poles(refs), 2) right inferior parietal lobe (refs), and 3) left lingual gyrus (refs) y Man-made items > living things -- three areas seen in more than one study: 1) left posterior middle temporal cortex (refs), 2) left pre-motor cortex (refs), and 3) left lingual gyrus (refs) yAll other areas have been seen in only a single study zWe hypothesized that this variability was due to small, context- specific effects and investigated this using a multi-factorial analysis

Design zData from 7 PET studies of category specificity StudyCategoriesStimuliTask 1. Mummery et al (1996) A, TSpoken words Category fluency 2. Mummery et al (1998) A, TWritten words Semantic & syllable decisions 3. Moore & Price (1999a) A, F, T, VPicturesNaming 4. Moore & Price (1999b) A, F, T, VWritten wordsMatching and pictures 5. Moore & Price (1999b) A, F, T, VPicturesNaming 6. Gorno-Tempini (2000) Fa, A, TPicturesNaming 7. Phillips et al (submitted) F, TWritten wordsSemantic & screen and picturessize decisions Abbreviations: A=animals, F=fruit, Fa=famous faces, T=tools, V=vehicles.

Analysis zSingle multi-factorial analysis with three factors: 1) Category (man-made vs. living things) 2) Task (semantic vs. non-semantic) 3) Stimulus type (words vs. pictures) to evaluate the effects of category in different contexts zData collected from 60 (53M, 7F) native English speakers on a single PET scanner.

Results zNo main effects of Category and no significant interactions with Stimulus type zHighly significant Category x Task interactions zTools > Living things for semantic tasks only zPeak in left posterior middle temporal gyrus at ( ), SPM{Z}=5.30, p=0.005 (corrected) z = 0 L L R

Contrasts 1.Location decisions 2.Color decisions 3.Syllable decisions 4.Action decisions 5.Real Size decisions 6.Screen size decisions 7.Category fluency 8.Naming color pictures 9.Naming b/w pictures 10.Naming pictures 11.Reading words 12.Word-Picture matching Effect size (%rCBF) L. post. middle temporal gyrus ( ) Manmade - Living Contrasts Semantic tasks Nonsemantic tasks Consistent tool advantage

Word-picture matching Picture naming L. post. middle temporal gyrus ( ) Key AAnimals FFruit VVehicles TTools BBaseline CNC. N. objects SNS. N. objects A F V T B A F V T CN SN Relative effect sizes Tool-specific? No. zTools > living things and vehicles BUT zSimple nonobjects also activated this region

T F Faces A T Body Parts Relative effect sizes Semantic decisions Picture naming Action Perceptual { { Key AAnimals FFruit TTools Combine this slide into last one? zIn addition, this region is activated by: 1) Action decisions (for both tools and fruit) and 2) Naming pictures of body parts

Living things > manmade items (Tasks requiring identification only) z = -8 y = 8 z = -24 zR. anterio-medial TP extending along medial surface. SPM{Z}=5.2, p=0.01 (corrected) zL. insula extending into anterio-medial TP. SPM{Z}=4.1, p=0.086 (corrected) R R L R L L

Consistent living things advantage Effect size (%rCBF) Naming pictures Acknowledging Reading Acknowledging Action decisions Real Size decisions Screen size decisions Location decisions Color decisions Syllable decisions Naming color pictures Naming b/w pictures W-P matching Naming pictures Category fluency R. Ant. Temp. Pole ( ) L. Ant. Temp. Pole ( ) Living - Manmade Contrasts Requires identification Other tasks

Left TP ( ) Right TP ( ) Relative effect sizes A F V T B A F V T Faces A T BP W-P matching Picture naming Picture naming Category-specific? No. Separate into 2 slides?? Animals, fruit, and faces all activate these regions *

Left TP ( ) Right TP ( ) Relative effect sizes A F V T B A F V T Faces A T BP W-P matching Picture naming Picture naming Category-specific? No. Separate into 2 slides?? Animals, fruit, and faces all activate these regions *

Summary zRobust evidence of anatomical specialisation for semantic categories: yTools activated left posterior middle temporal region yLiving things activated anterio-medial temporal poles zSmall, context-specific effects: yTool activation only in semantic tasks yLiving thing activation for tasks requiring identification Q:How do these findings relate to cognitive theories of category specificity?

Conclusions zResults illustrate clear specialisation within the semantic system by demonstrating an anatomical double dissociation between living things and manmade items zInconsistent with accounts based on an undifferentiated semantic system

Conclusions zResults were not specific to individual categories yTool area responded to action decisions for fruit, naming body parts, and pictures of non-objects yTemporal poles were activated by animals, fruit, and famous faces zInconsistent with evolutionary account of neural regions specialised for individual categories

Conclusions zResults were most consistent with distinct regions for different types of information zPosterior middle temporal region responds to actions associated with graspable objects zAnterior temporal poles may respond to greater semantic integrating information R L L Replace this with an axial slice through ant TPs (z=-20)

References