Unformatted text preview: k Switching!
Inhibitory Control! Selection of Task-Relevant Information!
Stroop Task! red!
red! Must be able to selective from various, competing action plans what it is we want to carry out, what plan we want to do. That is what this function is about -- the PFC selecting that action plan
and biasing that behavior to that one particular goal. Nicely seen in the Stroop Task. Goal of this task is simply call out the color of box that you see, and the color of the word (ignore the word).
The problem is you have 2 streams of competing information -- you have the color information that is coming through and also the word information that is well-learned at the same time, and
both competing for a response. And the PFC is necessary for selecting the right one. Selection of Task-Relevant Information!
A Model of Prefrontal Control during the Stroop Task! With no top-down prefrontal control, the word-reading
pathway is much stronger than the color pathway. This
leads to the inappropriate response of “green.”! However, with the exertion of top-down prefrontal control,
the intent to name the color of the word biases processing
in favor of activity ﬂowing along this pathway. This leads
to the appropriate response of “red.”!
Suggests how the PFC does this. Under no control, the PFC is not trying to bias a particular response. What is going to happen is that you have the
color red coming through, and you have to make a verbal response to say red, but you also have the word reading pathway (say green) and that is also
going to compete for that verbal response. It turns the word-reading response is the human brain is much more potent than the color naming response.
So typically in this situation, most people feel it is hard to say red, and not green. So the reading pathway is much stronger than color naming. When the
goal has changed to name the color of the word, and not the word itself, you have the PFC come into play, and the connections coming from the PFC to
the posterior regions that are trying to bias these color pathways in order to come up with that verbal respo...
View Full Document
- Fall '11
- Task Switching, PFC