PrepTest 134, Section 2, Question 20
Neural connections carrying signals from the cortex (the(43 more words not shown)
The argument's conclusion follows logically(8 more words not shown)
- AThe influence that(24 more words not shown)
- BNo other brain(11 more words not shown)
- CThe region of(24 more words not shown)
- DThe amygdala is(12 more words not shown)
- EThe degree of(17 more words not shown)
Reading the argument
Which direction carries the greater influence: thought to emotion, or emotion to thought? The argument favors the second because the connections from the amygdala to the cortex are better developed than the connections going back the other way.
That sounds plausible. But better developed doesn't yet mean more influential. We know a difference in the connections' development, and the author turns it into a difference in how strongly one region affects the other. To make the conclusion follow, give us a rule connecting those two things: more-developed connections transmit more influence.
What we’re looking for
Keep the comparison narrow. We aren't asking which part of the brain has the greatest influence overall. We are comparing these two directions between these two regions.
Working the answers
- A
Dependence between their influences on the rest of the brain doesn't tell us which region has more influence on the other. The answer also leaves the development of the connections out. We need to use that specific difference to establish the direction of greater influence.
- B
Perhaps the amygdala has more influence on the cortex than any other region does. That would still compare different inputs to the cortex, rather than comparing the amygdala's influence on the cortex with the cortex's influence on the amygdala. B doesn't settle our two-direction comparison.
- C
This is tempting because it mentions both development and influence. But it identifies which region has the most influence on the cortex. It doesn't compare the two opposite pathways between the cortex and the amygdala. Nor are we told that the amygdala has the most highly developed connections to the cortex out of every brain region. The shared vocabulary doesn't supply the rule our particular comparison needs.
- D
Whether another region controls the amygdala doesn't establish how much influence passes along either of these two pathways. The amygdala could itself be influenced by something else and still exert more influence on the cortex than the cortex exerts on it. D doesn't connect pathway development to transmitted influence.
- ECorrect
Direct proportionality means greater development corresponds to greater transmitted influence. The connections from amygdala to cortex are better developed than those from cortex to amygdala. Under E's rule, they therefore transmit more influence, which is the conclusion.
A third region could have an even stronger influence somewhere in the brain without changing this result. We only need the relative development of the two pathways to establish their relative influence. E supplies exactly that connection.
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