Talk:CCNBook/Executive

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YM: Have not talked about prolonged development or relative size in humans compared to other species.

MJF: Suggestion - get rid of Patch for basic PBWM model (doesn't do anything for a single stripe model and best to make as simple as possible - already too complex for novice to understand).

MJF: Second suggestion: it would be nice if there is time to follow up on SIR with a multi-stripe model to show the advantages of BG selective gating.. possible the 12-ax simulation, or maybe the best thing would be to just do the sir-2 task (the original motivation for making this model in first place!). In principle that could be added as a second network and task within the overall sir project. I think this would be nice -- important to start off with a simple one loop net and a basic task, and then motivate how all these mechs are important for harder problems in a multi-stripe net. (otherwise it's a bit unclear why spend all that effort in the chapter discussing stripes etc, and also don't really need a BG in the first place for sir1).

MJF: Third suggestion: There is a lot here, and readers unfamiliar with PBWM are likely to get lost and give up. I suggest leaving the output gating aspect as a follow up after the initial discussion of input gating, rather than making it central to the overall model. So for example the diagram in the figure showing dynamics of LV and BG_mnt_go and BG)out_go could instead only include the maint component, and then after the complete pbwm model is presented with just input gating and shows how it solves these kinds of tasks, the idea of output gating can be introduced and summarized, with a subtopic that describes this stuff in more detail, including the dynamics etc. Otherwise I fear it will be hard to appreciate not only pbwm, but also the basic stroop model etc.

FC: broken down by section for approx. first half:

Executive Function: From Working Memory to Cognitive Control

The introduction of the chapter may serve as a historical introduction but is a lot longer than necessary. The first two paragraphs could be greatly reduced. The third paragraph contains the bulk of substance, and the beginning of the fourth paragraph is relevant up until the mention of Donald Hebb. The sorts of historical curiosities here are usually found in entertaining and informative "boxes" in text books because they detract from the focus of the text. Most of the rest of this book has been focused and to the point; this introduction feels out of place.

Higher how?

We've jumped from "executive function" (the title of the chapter) to "higher-level cognition", and it's unclear (in the text) how.

It should be made clearer the extent to which "...using formal mathematics;...the use of careful logical reasoning..." are considered higher level cognition, especially because it's been stated that patients with frontal lobe damage show little to no deficits in IQ.

Following the list: "Trying to make theoretical sense out of this disparate list of activities" - this seems strange because there are striking commonalities in several list items. In fact there's a lot of structure to the list already:

e.g. These two seem like they might be related:

  • Behavioral flexibility
  • Overcoming prepotent responses

And these all seem to be facets of "doing non-trivial stuff":

  • Internally directed actions
  • Goal-directed behaviors
  • Directing attention and/or monitoring the environment
  • Evaluating one's own performance
  • Conscious awareness

Perhaps the structure and relationships between these roles could be made clearer. -- Regarding "top-down biasing": the notion of "top-down" is new to the book at this point and is introduced without much more than context. Also, I'm almost certain "biasing" is a new concept as well. I believe this is the correct place to introduce the concept, but it should be built up and not just thrust on the reader.

Before going into the PBWM framework, it's worth noting that the useful concept of an "executive" hasn't been mentioned at all. Perhaps the chapter wants to sidestep the issue of the homunculus-- in this case, concepts like biasing and action selection seem like a good way to skirt the issue, but the title of the chapter should be changed.

PBWM

In the second paragraph, the monkey behavior is never described--this would be like not saying how Phineas Gage's personality changed, just that it did.

In general, ideas can be presented much more directly:

"Thus, even way back then this simple task illustrated very well two fundamental, but interrelated, aspects of executive function: 1) working memory (remembering the target location), and; 2) cognitive control (overcoming the prepotent tendency to respond immediately and waiting until the appropriate time). After Jacobsen's work, it thus was becoming pretty clear that the frontal lobes were important for this kind of delayed responding, but why? And, in what way?"

could turn into (after the description of the monkeys' behavior):

"This behavior served as evidence that the frontal lobes were important for two fundamental, but interrelated, aspects of executive function: 1) working memory (remembering the target location), and; 2) cognitive control (overcoming the prepotent tendency to respond immediately and waiting until the appropriate time)".

Which could be further simplified by providing a sufficient explanation of cognitive control earlier in the chapter, thus obviating the need for the second parenthetical.

The next two paragraphs can be greatly reduced to a short description of active maintenance.

The introduction of the Stroop effect here is odd and maybe belongs much earlier in the chapter.

The Biology That Underlies the PBWM Framework

This introduction to this section, up to and not including "Mechanisms of robust active maintenance", can probably be cut. I'm not sure what the point is. A lot of brain areas are labeled without context or stated purpose. For example, the end of paragraph 3:

"Of the three, the last area has been the most studied by researchers into higher-cognitive function and, thus, it has become all too common for some to think only about the DLPFC as the site of higher-level cognition. However, with the advent of more sophisticated experimental techniques in recent years that have facilitated the study of these harder to reach areas, it has become clear that the other two areas are of equal importance for many aspects of executive function."

The function of these areas isn't discussed. The method of study isn't mentioned. And the next paragraph just subdivides the areas further before the reader is presumably allowed to forget all of this anatomy. The "Frontal Lobe" bullet point from chapter 5 provides clearer and more relevant anatomical information. It's noteworthy that in the summary of this chapter, it jumps from active maintenance straight to gating.


The rest...

The rest of the chapter is a bit better, probably due to the increased focus of the sections. It's still too long and, like the rest of the chapter, unnecessarily historical.