Self-study
Support Neural connections carrying signals from the cortex (the brain region responsible for thought) down to the amygdala (a brain region crucial for emotions) are less well developed than connections carrying signals from the amygdala up to the cortex. █████ ███ ████████ ██████ █ ███████ █████████ ██ ███ ██████ ████ ████ ██████
Summary
The influence that the amygdala has on the cortex is greater than the influence that the cortex has on the amygdala, because the neural connections in the former are more well-developed.
Missing Connection
The author has made a conclusion about comparative influence, but has only supported this with a statement about comparative development. For the conclusion to validly follow from the premises, we need to know that influence on the amygdala and cortex is directly impacted by the development of neural connections.
20.
The argument's conclusion follows logically ██ █████ ███ ██ ███ █████████ ██ ████████
a
The influence that ███ ████████ ██████ ██ ███ ████ ██ ███ █████ ██ █████████ ██ ███ █████████ ████ ███ ██████ ██████ ██ ███ ████ ██ ███ ██████
We are discussing the influence of amygdala on cortex, and of cortex on amygdala. We aren’t talking about overall brain influence. Also, (A) does not define in what way the amygdala influence is dependent on cortex influence.
b
No other brain ██████ ██████ ████ █████████ ██ ███ ██████ ████ ████ ███ █████████
(B) does not guarantee the author’s conclusion. The amygdala can win first prize for cortex influence, like (B) says, and the cortex could still have more influence on the amygdala (contrary to our conclusion).
c
The region of ███ █████ ████ ███ ███ ████ █████████ ██ ███ ██████ ██ ███ ███ ████ ███ ███ ████ ██████ █████████ ██████ ███████████ ██ ███ ███████
We are comparing amygdala-to-cortex influence vs. cortex-to-amygdala influence. We are not comparing X vs. Y vs. Z influences on the cortex, nor do we know which region of the brain has the most highly developed connections to the cortex.
d
The amygdala is ███ ██████ ██████████ ██ ███ ██ ████ █████ ███████ ██ ███ ██████
Whether the amygdala is or isn’t controlled by other regions of the brain doesn’t affect the argument. The amygdala can be entirely self-piloting, like (D) says, and the cortex-to-amygdala influence could be greater (contrary to the conclusion), so (D) does not guarantee the conclusion.
e
The degree of ███████████ ██ █ ███ ██ ██████ ███████████ ██ ████████ ████████████ ██ ███ █████████ ███████████ ██████ █████ ████████████
This is what we predicted, and it allows the conclusion to be validly drawn. If (E) is true, then the fact that the amygdala-to-cortex pathway has more well developed connections than cortex-to-amygdala means that amygdala will have more influence on the cortex than vice versa.