Differential dorsolateral prefrontal cortex activation during a verbal n-back task according to sensory modality

Area of Science:

• Cognitive Neuroscience
• Neuroimaging

Background:

• The n-back task is a standard cognitive paradigm used to assess working memory capacity.
• Previous functional neuroimaging studies indicate bilateral frontoparietal activation, particularly in the dorsolateral prefrontal cortex (DLPFC), during n-back task performance in healthy individuals.

Purpose of the Study:

• To compare brain activation patterns using functional magnetic resonance imaging (fMRI) between auditory and visual versions of the 2-back task.
• To investigate the neural correlates of working memory across different sensory modalities.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was employed.
• Thirteen healthy volunteers performed both a verbal 2-back task (auditory stimuli) and a visual 2-back task.
• Conjunction analysis was used to identify overlapping and distinct brain activation patterns.

Main Results:

• A conjunction analysis revealed significant bilateral activation in frontoparietal areas, including the DLPFC, for both tasks, supporting the supramodal nature of working memory.
• The auditory task elicited greater activation in the left DLPFC and superior temporal gyrus compared to the visual task.
• The visual task showed greater activation in posterior brain regions and the anterior cingulate cortex relative to the auditory task.

Conclusions:

• Working memory engages largely overlapping neural networks irrespective of stimulus modality, highlighting its supramodal characteristics.
• Task-specific activations suggest modality-specific processing within these networks.
• Understanding these modality-specific differences is crucial for selecting appropriate tasks in future clinical neuroimaging studies.