Task-Relevant Representations and Cognitive Control Demands Modulate Functional Connectivity from Ventral Occipito-Temporal Cortex During Object Recognition Tasks

Abstract

The left ventral occipito-temporal cortex (vOTC) supports extraction and processing of visual features. However, it has remained unclear whether left vOTC-based functional connectivity (FC) differs according to task-relevant representations (e.g., lexical, visual) and control demands imposed by the task, even when similar visual-semantic processing is required for object identification. Here, neural responses to the same set of pictures of meaningful objects were measured, while the type of task that participants had to perform (picture naming versus size-judgment task), and the level of cognitive control required by the picture naming task (high versus low interference contexts) were manipulated. Explicit retrieval of lexical representations in the picture naming task facilitated activation of lexical/phonological representations, modulating FC between left vOTC and dorsal anterior-cingulate-cortex/pre-supplementary-motor-area. This effect was not observed in the size-judgment task, which did not require explicit word-retrieval of object names. Furthermore, retrieving the very same lexical/phonological representation in the high versus low interference contexts during picture naming increased FC between left vOTC and left caudate. These findings support the proposal that vOTC functional specialization emerges from interactions with task-relevant brain regions.

Keywords: cognate; fMRI; language production; semantic; ventral occipito-temporal cortex.

Figure 1

Experimental sessions and trial timing. The trials analyzed in the present study were L1 naming blocks from the L1 naming/L3 naming and the L1 naming/L1 size-judgment sessions. We also analyzed L1 size-judgment blocks from the L1 naming/L1 size-judgment session.

Figure 2

All tasks against rest. (A) GLM results for the different task conditions against rest. For all the contrasts, a voxel-level significance threshold was set at P < 0.001 with FWE correction applied at the critical cluster level set at P < 0.05. (B) FC results for each task condition against rest. These results were corrected for multiple comparisons by using a voxel-level significance threshold set at P < 0.001, and an FWE-corrected cluster level significance threshold set at P < 0.05. (C) The left vOTC seed (yellow) used to compute FC analyses. The seed overlaps with brain voxels commonly activated by all the tasks against rest, as revealed by the formal conjunction analysis. Conjunction analysis results were corrected for multiple comparisons by using a voxel-level significance threshold set at P < 0.001, and an FWE-corrected cluster level significance threshold set at P < 0.05.

Figure 3

Whole-brain left vOTC-based FC results for the cognate effect (non-cognate versus cognate) in LIC-L1 naming. The results were corrected for multiple comparisons by using a voxel-level significance threshold set at P < 0.001, and an FWE-corrected cluster level significance threshold set at P < 0.05.

Figure 4

L1 naming in high versus low-interference contexts. (A) Left vOTC-based whole-brain FC results. The results were corrected for multiple comparisons by using a voxel-level significance threshold set at P < 0.001, and an FWE-corrected cluster level significance threshold set at P < 0.05. (B) Accuracy measures for HIC-L1 naming and LIC-L1 naming. The graph depicts density, the grand average (mean ± standard deviation; errors bars indicate 5th and 95th percentiles), and individual means (pink dots).