Response of the multiple-demand network during simple stimulus discriminations

Tanya Wen,Daniel J Mitchell,John Duncan

doi:10.1016/j.neuroimage.2018.05.019

Tanya Wen, Daniel J Mitchell + Show 1 more

Open Access

https://doi.org/10.1016/j.neuroimage.2018.05.019

Copy DOI

Abstract

The multiple-demand (MD) network is sensitive to many aspects of task difficulty, including such factors as rule complexity, memory load, attentional switching and inhibition. Many accounts link MD activity to top-down task control, raising the question of response when performance is limited by the quality of sensory input, and indeed, some prior results suggest little effect of sensory manipulations. Here we examined judgments of motion direction, manipulating difficulty by either motion coherence or salience of irrelevant dots. We manipulated each difficulty type across six levels, from very easy to very hard, and additionally manipulated whether difficulty level was blocked, and thus known in advance, or randomized. Despite the very large manipulations employed, difficulty had little effect on MD activity, especially for the coherence manipulation. Contrasting with these small or absent effects, we observed the usual increase of MD activity with increased rule complexity. We suggest that, for simple sensory discriminations, it may be impossible to compensate for reduced stimulus information by increased top-down control.

Highlights

Diverse studies examining a range of cognitive demands have found of a set of frontal-parietal regions that are consistently involved in a variety of tasks, ranging from response inhibition to working memory to decision making (e.g., Duncan and Owen, 2000; Fedorenko et al, 2013; Niendam et al, 2012; Stiers et al, 2010)
We pursued mixed previous findings suggesting a partial exception – in some cases, multiple demand (MD) activity seems largely insensitive to the difficulty of sensory discriminations
To obtain the strongest possible test of such insensitivity, using a motion coherence task, we manipulated two aspects of sensory difficulty over the widest possible range, from very easy to close to chance

Summary

Introduction

Diverse studies examining a range of cognitive demands have found of a set of frontal-parietal regions that are consistently involved in a variety of tasks, ranging from response inhibition to working memory to decision making (e.g., Duncan and Owen, 2000; Fedorenko et al, 2013; Niendam et al, 2012; Stiers et al, 2010). While activity in frontal-parietal areas increased with the addition of a distractor, exposure duration had little effect To interpret their findings, Han and Marois (2013) appealed to the distinction made by Norman and Bobrow (1975), between data-limited and resource-limited behavior. In line with a link of MD activity to attentional investment, Han and Marois (2013) used these ideas of dataand resource-limitation to explain their findings They proposed that, in their task, brief exposure duration created data limits, which could not be offset by increased fronto-parietal recruitment, while adding a distractor introduced resource limits by calling for increased attentional focus. In Experiment 2 we reexamined coherence and irrelevant-dots conditions in a new group of participants, and compared these sensory demands with a manipulation of rule complexity

Methods

Results

Discussion