Neural Activity Associated with the Processing of Familiar Information in Working Memory

• Author / Creator

  Ng, Benson PS

• Purpose: Emerging data indicate that processing of familiar and novel faces involves different neural mechanisms; familiar face perception is associated with more widespread neural activity in prefrontal and temporal regions compared with novel faces (Leveroni et al., 2000). Nevertheless, investigation of working memory in the context of personally significant information is limited. Method: Sixteen healthy individuals performed n-back tasks while undergoing functional magnetic resonance imaging at the University of Alberta. A yoked design was used to pair familiar faces (family members / close friends) with novel faces across participants (Roye, Schroger, Jacobsen, & Gruber, 2010). Participants compared the current face with the one before (1-back) or two faces before (2-back). There were 6 runs, each consisting 6 blocks of 1-back and 2-back conditions. Statistical parametric mapping (SPM) 8 was used for statistical analysis. Results: Hit rates were comparable between 1-back and 2-back conditions for familiar faces (93.7% and 89.1% respectively; p>0.05) but were slightly higher in 1-back than 2-back conditions for novel faces (89.1% and 82.7% respectively, p<0.05). In the 1-back condition, familiar faces demonstrated substantial activations in prefrontal, occipital, and cerebellar regions compared with novel faces. In the 2-back condition, both familiar and novel faces activated the typical frontoparietal working memory network; however, novel faces activated more extensively and also activated the insula and thalamus, whereas familiar faces activated less extensively and also activated the cerebellum. In addition, the main effect of familiarity and pair-wise comparison of familiar versus novel faces on the 2-back condition showed strong neural activity in the anterior cingulate cortex. Region of interest (ROI) analysis revealed dissociable pattern of brain-behavior relationship: Neural activity for familiar 2-back condition showed positive correlation with hit rate and negative correlation with reaction time over many regions such as the superior and medial frontal gyrus, the occipital cortex, and the anterior cingulate cortex, while neural activity for novel 2-back condition showed negative correlation with hit rate and positive correlation with reaction time at the medial frontal gyrus. This further suggests that familiar information, relative to novel information, has a facilitative effect on working memory. Conclusions: Familiar and novel faces demonstrated different patterns of activation in working memory tasks. Although both conditions activated the typical working memory network, familiar faces demonstrated fewer actiavtions than novel faces in the 2-back condition, suggesting that working memory on familiar faces requires less effort. In addition, the neural activity associated with the processing of familiar faces also demonstrated a pattern of facilitation, with greater neural activity related to higher accuracy rate and lower reaction time on task; such pattern was absent for novel faces. From the results of the 1-back condition, the processing of familiar faces appeared to elicit more extensive activations, consistent with previous findings that more widespread neural changes in familiar face perception. The results suggest a differential use of personally significant information in face perception and working memory training.

• Subjects / Keywords

  • FMRI
  • Personally familiar face
  • N-back
  • Working memory
  • Familiar information

• Graduation date

  Fall 2017

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R31J97N7W

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.