1. (Example) Class Presentation: John Desmond
Blakemore, S. J., Wolpert, D. M., & Frith, C. D. (1998). Central cancellation of self-produced tickle sensation. Nat Neurosci,
1(7),

2. Introduction
We are constantly bombarded by sensations from multiple sources
It is adaptive to be able to disregard sensations arising from our own movements

3. Introduction
This ability to predict consequences of our actions may result in differential perception of identical sensory inputs
For example, it is very difficult to tickle oneself

4. Previous Investigations
Introducing delay (200 ms) between movement of left hand and receiving tactile stimulation of right hand increased tickle rating
Thus, attenuation of self-produced tactile stimulation may be due to a temporally precise cancellation based on sensory predictions

5. Possible Mechanism: Forward Model
Forward models receive an efference copy of motor commands and generate a corollary discharge that predicts the consequences of movements
Comparing this prediction with actual sensory feedback could provide the basis for distinguishing self-generated vs. external sensory signals

6. Forward Model

7. Likely Site of Forward Model: Cerebellum

8. Purpose of Present Experiment
Compare functional brain activation for self-produced versus externally produced tickle sensation
Hypothesis: Cerebellar activation will distinguish these two types of stimulation

9. Methods 6 right handed healthy subjects Mean age 33 years
fMRI scanning during 4 conditions of a 2x2 factorial design

10. Methods

11. Methods Each condition lasted 32.8 sec
Each subject was scanned for all 4 conditions
Each condition was replicated 12 times
Condition order was counterbalanced
Subjects instructed to keep eyes closed

12. fMRI Methods: Data Acquisition
2 Tesla Siemens Scanner
48 axial images per volume
Inplane resolution: 3 mm x 3 mm
One volume collected every 4.1 s
Thus, one block (32.8 s) = 8 volumes

13. fMRI Methods: Data Analysis
SPM97
Volumes were motion corrected
Normalized into Talairach space
Spatial Smoothing with 6 mm FWHM
Statistical analysis using general linear model
Weighted contrasts performed to create statistical t maps overlaid onto anatomical scan

14. Results: Main Effects of Self-generated Movement
(A+B) – (C+D)

15. Results: Main Effects of Tactile Stimulation
(A+C) – (B+D)

16. Results: Interaction of Tactile Stimulation with Self-generated Movement
(C-D) – (A-B)

17. Results: Parietal Operculum
Interaction
(C-D) – (A-B)
A-B not different
from 0: ie., any
movement
attenuates
activation

18. Results: Cingulate Interaction (C-D) – (A-B) A-B not different
from 0: ie., any
movement
attenuates
activation

19. Results: Cerebellum
Interaction
(C-D) – (A-B)
A-B is different
from 0

20. Discussion
Differential sensory responses to a self-generated movement do not occur at the level of somatosensory cortex.
Results suggest that specific sensory predictions occur at the level of the anterior cerebellar cortex.

21. Conclusion
We conclude that decrease of activity in somatosensory cortex to self-produced tactile stimuli occurs because such stimuli match the predicted sensory feedback of the movement and that this prediction occurs in the cerebellum.

22. Conclusion
Self-generated tickle External tickle ++