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Sam Gilbert Institute of Cognitive Neuroscience & Department of Psychology

This study explores the role of the rostral prefrontal cortex (Area 10) in selecting between stimulus-oriented and stimulus-independent thought processes in typical development and autism spectrum disorders. Using various tasks and neuroimaging techniques, the study investigates the functional specialization within BA 10 and its implications for social cognition and executive functions.

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Sam Gilbert Institute of Cognitive Neuroscience & Department of Psychology

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  1. Social versus nonsocial functions of rostral prefrontal cortex in typical development and autism spectrum disorders Sam Gilbert Institute of Cognitive Neuroscience & Department of Psychology

  2. Rostral PFC (Area 10)

  3. Gateway hypothesis (Burgess, Simons, Dumontheil & Gilbert, 2005; Burgess, Dumontheil & Gilbert, 2007) • BA 10 supports selection between stimulus-oriented and stimulus-independent thought

  4. Direct test (Gilbert, Frith & Burgess, 2005; EJN) • Three separate tasks, which participants could accomplish either by using visually-presented information, or by doing the same task “in their head” • Participants alternate between “stimulus-oriented” and “stimulus-independent” phases

  5. Direct test (Gilbert, Frith & Burgess, 2005; EJN) Stimulus-Oriented (SO) Stimulus-Independent (SI) Task 1 3-54s (mean: 11s)

  6. Direct test (Gilbert, Frith & Burgess, 2005; EJN) Stimulus-Oriented (SO) Stimulus-Independent (SI) Task 1 3-54s (mean: 11s) ¿ A D G ? ? Task 2

  7. Stimulus-Independent > Stimulus-Oriented: no active voxels Stimulus-Oriented > Stimulus-Independent: Direct test (Gilbert, Frith & Burgess, 2005; EJN) p < .05 corrected

  8. Direct test (Gilbert, Frith & Burgess, 2005; EJN) • Medial BA10: focusing attention on the external environment • But how can we know that this region are causally involved in selection between stimulus-oriented and stimulus-independent thought? • Activity in medial BA10 has previously been attributed to task-unrelated thought processes during low-demand conditions (e.g. Mason et al., 2007; McKiernan et al., 2003; Wicker et al., 2003)

  9. % signal change SI Daydreaming during (easy) stimulus-oriented conditions? (Gilbert, Simons, Frith & Burgess, 2006; JEP:HPP) Stimulus-Oriented (SO) > Stimulus-Independent (SI)

  10. Daydreaming during (easy) stimulus-oriented conditions? (Gilbert, Simons, Frith & Burgess, 2006; JEP:HPP) % signal change Stimulus-Oriented (SO) > Stimulus-Independent (SI) Correlation with baseline RT SI

  11. Mentalising / Theory of Mind Frith & Frith (2003) “the mentalizing region of the MPFC is engaged when we attend to our own mental states as well as the mental states of others”

  12. Multi-Task Mentalising y=60 x=0 z=0 Functional specialization within BA 10 (Gilbert, Spengler, Simons, Steele, Lawrie, Frith & Burgess, 2006; JoCN)

  13. Functional specialization within BA 10 (Gilbert, Spengler, Simons, Steele, Lawrie, Frith & Burgess, 2006; JoCN) Predictions of the classification algorithm: Multi-Task Episodic Retrieval Mentalising Prediction accuracy: 74% (p < .0000001)

  14. Functional specialization within BA 10 (Gilbert, Spengler, Simons, Steele, Lawrie, Frith & Burgess, 2006; JoCN) % medial activations 32% (N=99) Emotion Mentalizing 0% (N=2) 96% (N=24) 37% (N=8) Medial activations associated with contrasts involving both mentalizing and emotional materials May play a role in attending to emotional states, rather than representing those emotional states themselves

  15. 2 x 2 factorial design (cf. additive factors logic): Mentalising versus attention in medial rostral PFC (Gilbert, Williamson, Dumontheil, Simons, Frith & Burgess, 2007, SCAN) Attentional focus Mentalising

  16. Mentalising versus attention in medial rostral PFC (Gilbert, Williamson, Dumontheil, Simons, Frith & Burgess, 2007, SCAN) Stimulus-Oriented (SO) Stimulus-Independent (SI) Task 1 ¿ A D G ? ? Task 2

  17. A V D S Mentalising versus attention in medial rostral PFC (Gilbert, Williamson, Dumontheil, Simons, Frith & Burgess, 2007, SCAN) Helpful / Unhelpful? Spatial task Mentalising etc. ¿ Y G ? ? Alphabet task Non-mentalising Fast / Slow? Stimulus- independent (SI) Stimulus- oriented (SO) Stimulus- oriented (SO) Phase 3-18s (mean: 11s) 5s 21-39s (mean: 30s)

  18. Mentalising versus attention in medial rostral PFC (Gilbert, Williamson, Dumontheil, Simons, Frith & Burgess, 2007, SCAN) “I was thinking about whether you could see if I was stuck … and what was coming up on your screen … I was more aware of the human element entering into the equation”

  19. Mentalising versus attention in medial rostral PFC (Gilbert, Williamson, Dumontheil, Simons, Frith & Burgess, 2007, SCAN) x = -8 x = -6 x = -4 Mentalising SO > SI Overlap x = 0 x = -2 x = +2 x = +6 x = +4 x = +8

  20. Mentalising versus attention in medial rostral PFC (Gilbert, Williamson, Dumontheil, Simons, Frith & Burgess, 2007, SCAN) Direct comparison Meta-analysis Multiple-task co-ordination Mentalising Episodic Memory SO > SI Mentalising > Non-mentalising

  21. Executive functions in autism spectrum disorders (Gilbert, G. Bird, Brindley, Frith & Burgess, in press, Neuropsychologia) • Neuroimaging studies investigating ASD suggest functional differences in medial rostral PFC during mentalizing tasks (e.g. Castelli et al., 2002). Will similar effects be seen in a different task that activates a similar region of medial PFC? • Rostral PFC has been implicated in executive function tests involving multitasking in ill-structured situations (e.g. Six Element Tests; Burgess, 2000). Abnormal performance in ASD has been reported particularly in such tasks (Hill & C. Bird, 2006).

  22. Executive functions in autism spectrum disorders (Gilbert, G. Bird, Brindley, Frith & Burgess, in press, Neuropsychologia) p = .15 p = .75

  23. Stimulus-Independent Phase Stimulus-Oriented Phase Stimulus-Oriented Phase A B Z P M F G A B C D E F G time

  24. Stimulus-Oriented > Stimulus-Independent Control: ASD:

  25. Stimulus-Oriented > Stimulus-Independent Control: ASD: ASD > Control:

  26. Executive functions in autism spectrum disorders (Gilbert, G. Bird, Brindley, Frith & Burgess, in press, Neuropsychologia) Control SO > SI ASD

  27. Executive functions in autism spectrum disorders (Gilbert, G. Bird, Brindley, Frith & Burgess, in press, Neuropsychologia) Control SO > SI ASD Control participants SO > SI Mentalising

  28. A V D S Mentalising versus attention in ASD (Gilbert, Meuwese, Towgood, Frith & Burgess, submitted) Helpful / Unhelpful? Spatial task Mentalising etc. ¿ Y G ? ? Alphabet task Non-mentalising Fast / Slow? Stimulus- independent (SI) Stimulus- oriented (SO) Stimulus- oriented (SO) Phase 3-18s (mean: 11s) 5s 21-39s (mean: 30s)

  29. Mentalising versus attention in ASD (Gilbert, Meuwese, Towgood, Frith & Burgess, submitted) • ASD group: N = 16, mean age = 32.2, mean FSIQ = 116 • Control group: N = 16, mean age = 30.9, mean FSIQ = 120 • 2x2x2x2 design: • Group (ASD, Control) • Task (Alphabet, Spatial) • Mentalizing (Mentalizing, Non-mentalizing) • Phase (SO, SI)

  30. Imaging data Mentalizing > Non-mentalizing SO>SI

  31. Imaging data ASD (Mentalizing – Non-mentalizing) > Control (Mentalizing – Non-mentalizing)

  32. 0.34**

  33. 0.34** 0.17*

  34. 0.11 0.04 0.03 0.34** 0.17* -0.11

  35. Present results

  36. Present results

  37. Mentalizing > Non-mentalizing SO>SI Alphabet task = - Spatial task

  38. Mentalizing > Non-mentalizing SO>SI Alphabet task = - Spatial task

  39. Mentalizing > Non-mentalizing SO>SI Alphabet task = - Spatial task = -

  40. Mentalizing > Non-mentalizing SO>SI Alphabet task = - Spatial task = -

  41. Mentalizing > Non-mentalizing SO>SI Alphabet task = - Spatial task = -

  42. p = 0.4 p = 0.000003

  43. ASD: increased functional specialisation in medial rostral PFC? lack of generalisation from one task to another ASD: reduced functional specialisation in medial rostral PFC? nothing to generalise from one task to another

  44. Split-half analysis: p = .0004 p = .0005

  45. Conclusions • Role of rostral PFC in selection between stimulus-oriented and stimulus-independent thought • This may underlie the involvement of rostral PFC in a wide variety of domains (e.g. prospective memory) • Considerable functional specialisation within rostral PFC: • Distinct roles of lateral versus medial subregions • Distinct regions of medial rostral PFC involved in social and nonsocial functions • Abnormal functional architecture of medial rostral PFC in autism spectrum disorders: functional specialisation may not generalise from one task to another

  46. Future questions: Multi Voxel Pattern Analysis (MVPA) One voxel • MVPA involves examining the distribution of activation across a set of voxels, typically on a participant-by-participant basis, rather than the group-averaged peak voxel.

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