Effects of age and gender on neural correlates of emotion imagery

Abstract

Mental imagery is part of people's own internal processing and plays an important role in everyday life, cognition and pathology. The neural network supporting mental imagery is bottom-up modulated by the imagery content. Here, we examined the complex associations of gender and age with the neural mechanisms underlying emotion imagery. We assessed the brain circuits involved in emotion mental imagery (vs. action imagery), controlled by a letter detection task on the same stimuli, chosen to ensure attention to the stimuli and to discourage imagery, in 91 men and women aged 14-65 years using fMRI. In women, compared with men, emotion imagery significantly increased activation within the right putamen, which is involved in emotional processing. Increasing age, significantly decreased mental imagery-related activation in the left insula and cingulate cortex, areas involved in awareness of ones' internal states, and it significantly decreased emotion verbs-related activation in the left putamen, which is part of the limbic system. This finding suggests a top-down mechanism by which gender and age, in interaction with bottom-up effect of type of stimulus, or directly, can modulate the brain mechanisms underlying mental imagery.

Keywords: age; emotion; fMRI; gender; imagery; limbic system.

FIGURE 1

Gender effects on task × stimuli interaction. Brain cluster in the right putamen with significantly higher fMRI response to task × stimuli interaction (emotion vs. motor imagery controlled by letter detection) in females compared with males (p < .05, cFWE corrected). The diagram shows the distribution of the cluster fMRI activation values (GLM t‐contrast) in females (red) and males (blue). GLM contrast values represent the linear combination of GLM β coefficients for the selected contrast.

FIGURE 2

Age influence on main effect task. Brain clusters with fMRI response to task (mental imagery vs. letter detection) inversely proportional to age (p < .05, cFWE corrected). The scatterplot shows the fMRI activation values (GLM t‐contrast) as function of age in the left insula (blue) and left mid cingulate cortex (orange). GLM contrast values represent the linear combination of GLM β coefficients for the selected contrast.

FIGURE 3

Age influence on main effect stimuli. Brain cluster in the left putamen with fMRI response to stimuli (emotional vs. motor verbs) inversely proportional to age (p < .05, cFWE corrected). The scatterplot shows the cluster fMRI activation values (GLM t‐contrast) as function of age in the cluster. GLM contrast values represent the linear combination of GLM β coefficients for the selected contrast.

FIGURE 4

Group‐level fMRI activations after removal of age, gender, and scanner effects. Brain clusters with significant fMRI response to emotional imagery task (first row), motor imagery task (second row), imagery task versus letter detection task (third row), emotional stimuli versus motor stimuli (fourth row), and task × stimuli interaction (fifth row) in the entire sample (p < .05, cFWE corrected). Red and blue clusters represent positive and negative BOLD responses to each contrast, respectively (T‐statistics ranging from 2 to 4). BOLD, blood oxygenation level dependent; cFWE, cluster family wise error; fMRI, functional magnetic resonance imaging.