W5L2 - fMRI Research 2

Question 1

What is reverse inference

Answer 1

Drawing conclusions about cognitive processes from the presence of activation

Question 2

What is the steps/logic in reverse inference, where is the problem

Answer 2

1. ) This study: Task A, Brain Region Z active
2. ) Other study: Cognitive process X, Brain Region Z active
3. ) Hence, Activation of Z = Cognitive Process X

Problem: (2) Not exclusive. Brain Region Z activate for many other cognitive processes/tasks

Question 3

Example of Reverse Inference Problem: Pre-Frontal Cortex. What has been suggested of anterior and posterior regions

Answer 3

More anterior regions (front) = Abstract Information

• Dorsal Axis: Abstractness of Rules
• Ventral Axis: Abstractness of Memory Representation

More posterior regions (back) = Specific content

Question 4

Example of Reverse Inference Problem: Pre-Frontal Cortex. What other studies found

Answer 4

Frontal cortex activated in lots of tasks

- Relative specialization instead of absolute specialization. “More strongly” as task difficult increases

Question 5

What is the “Multi-Demand” Network

Answer 5

Activation in a region - Does not imply region is doing that.

Many regions interact with one another for cognitive task

Question 6

In examining cognitive processes, what are the 2 things experiments must ensure

Answer 6

1. ) Quality of Task -> Experiment must manipulate cognitive process of interest
2. ) Specificity of Region -> Is it only this region that is activated?

Question 7

Why can’t we interpret null results in fMRI

Answer 7

No region was significantly stronger activated for task A vs. task B. Cannot conclude region is not involved in A/B

1. ) Statistical tests make it difficult for H1, not for H0 - can’t interpret null
2. ) Our method might just not be sensitive enough to detect small differences (e.g. 3x3x3mm. Might not pick up layer-dependent activity)