Different Neural Activities for Actions and Language within the Shared Brain Regions: Evidence from Action and Verb Generation

Abstract

The Inferior Frontal Gyrus, Premotor Cortex and Inferior Parietal Lobe were suggested to be involved in action and language processing. However, the patterns of neural activities in the shared neural regions are still unclear. This study designed an fMRI experiment to analyze the neural activity associations between action and verb generation for object nouns. Using noun reading as a control task, we compared the differences and similarities of brain regions activated by action and verb generation. The results showed that the action generation task activated more in the dorsal Premotor Cortex (PMC), parts of the midline of PMC and the left Inferior Parietal Lobe (IPL) than the verb generation task. Subregions in the bilateral Supplementary Motor Area (SMA) and the left Inferior Frontal Gyrus (IFG) were found to be shared by action and verb generation. Then, mean activation level analysis and multi-voxel pattern analysis (MVPA) were performed in the overlapping activation regions of two generation tasks in the shared regions. The bilateral SMA and the left IFG were found to have overlapping activations with action and verb generation. All the shared regions were found to have different activation patterns, and the mean activation levels of the shared regions in the bilateral of SMA were significantly higher in the action generation. Based on the function of these brain regions, it can be inferred that the shared regions in the bilateral SMA and the left IFG process action and language generation in a task-specific and intention-specific manner, respectively.

Keywords: MVPA; action; fMRI; inferior frontal gyrus; language; supplementary motor area.

Figure 1

The selected stimuli used in the fMRI experiment with high action consistency and familiarity. Twenty-four object nouns were selected, and the written noun words were scaled to 256 × 256 pixels with a light grey background. The corresponding English words are below each stimulus. For example, the “手包” in Chinese is the “handbag”. Each of the eight object nouns were highly correlated with grasping, pinching or pressing.

Figure 2

The fMRI experiment paradigm design. There were two scan runs in this experiment. One run comprises three tasks: NR, to silently read an object noun; NA, to perform a hand gesture to an object noun; NV, to silently generate a verb to an object noun. Before the task block, a visual cue was presented to prompt the task.

Figure 3

Activation maps for (a) NA > NR, (b) NV > NR and (c) NA > NV. Color bars represent t values. The threshold values of the activation maps were p < 0.001 at the voxel level and p < 0.05 at the cluster level with family-wise error (FWE) correction.

Figure 4

The overlapping activation regions of NA > NR and NV > NR in the bilateral SMA and the left IFG.

Figure 5

Shared regions for NA and NV. The red regions are shared-LSMA, the blue regions are shared-RSMA and the green regions are shared-LIFG.

Figure 6

Parametric estimates for NA-NR and NV-NR in shared regions. The mean parameters of NA-NR were significantly higher than those of NV-NR in the shared-LSMA and shared-RSMA.

Figure 7

The classification accuracy and standard error in each shared region and the chance level of 50%. The accuracy in all ROIs was significantly above the chance level.