Natasha Rajah, Associate Professor in the Department of Psychiatry at McGill University, delves into using brain scans of people of various ages and what it tells us about this natural process.
Natasha Rajah received her PhD at the University of Toronto and received her postdoctoral training at the University Berkeley. She began working at the Douglas Institute in 2005 as assistant professor in the Department of Psychiatry. In 2007, she received a salary New Investigator Award from the Institute of Aging and was promoted in 2011 to Director position of the new Brain Imaging Centre at the Douglas Institute.
Natasha Rajah research focuses on brain imaging studies in cognitive neuroscience of aging and memory. In particular, uses magnetic resonance imaging (MRI) multimodal to study how changes in activity and the volume of certain brain regions affect the functioning of neuronal networks that are important in episodic memory. To this end, it uses multivariate statistical methods to study directly the triple interaction between memory performance, volume and brain activity of certain brain areas and activation of the neural network, in subjects in youth health, to average age and older.
Middle-Age Memory Decline
In my research I use behavioral experiments and functional brain imaging methods, i.e. fMRI, to study what brain changes are associated with the memory decline we observe in healthy aging. In my most recent study, conducted in collaboration with my Ph.D. student Elizabeth Ankudowich and my research assistant Stamatoula Pasvanis, we used fMRI to test 112 young (19 – 35 yrs), middle-aged (40 – 58 yrs) and senior ( 60 – 76 yrs) adults’ memory for spatial and temporal details about past experiences. We obtained functional brain scans as they did these tests. Specifically, adults were presented with photographs of faces and asked to judge whether a face was pleasant/neutral while simultaneously encoding the spatial or temporal order of face stimuli. We later tested their memory for the spatial and temporal details. So adults were aware at encoding that what was important for the memory task was the spatial/temporal information and not the pleasantness information. The goal of this study was to determine when memory decline emerges in adulthood, and what brain changes accompany this change. We found memory decline started at early midlife (the 40s) and was associated with reduced activity in visual processing regions during memory retrieval. Senior adults (+60 yrs) also exhibited activation changes in brain regions important for strategy use (prefrontal cortex), attention (parietal cortex) and self-relevant information (parahippocampal cortex). We concluded that memory decline with age may be due to what information we attend do as we age, and that with age we attend less to objective visual details, i.e. the spatial and temporal details of the face, and more to subjective self-relevant information, i.e. the pleasantness of the face.