A right hemisphere role in cognitive reserve

Abstract

High levels of education, occupational complexity and/or premorbid intelligence are associated with lower levels of cognitive impairment than would be expected from a given brain pathology. This has been observed across a range of conditions including Alzheimer's Disease (Roe, et al., 2010), stroke (Ojala-Oksala, et al., 2012), traumatic brain injury (Kesler, et al., 2003), and penetrating brain injury (Grafman, 1986). This cluster of factors, which seemingly protect the brain from expressing symptoms of damage, has been termed 'cognitive reserve' (Stern, 2012). The current review considers one possible neural network which may contribute to cognitive reserve. Based on evidence that the neurotransmitter noradrenaline mediates cognitive reserve's protective effects (Robertson, 2013) this review identifies the neurocognitive correlates of noradrenergic (NA) activity. These involve a set of inter-related cognitive processes (arousal, sustained attention, response to novelty and awareness) with a strongly right hemisphere, fronto-parietal localization, along with working memory which is also strongly modulated by NA. It is proposed that this set of processes is one plausible candidate for partially mediating the protective effects of cognitive reserve. In addition to its biological effects on brain structure and function, NA function may also facilitate networks for arousal, novelty, attention, awareness and working memory which collectively provide for a set of additional, cognitive, mechanisms that help the brain adapt to age-related changes and disease. It is hypothesized that to the extent that the lateral surface of the right prefrontal lobe and/or the right inferior parietal lobe maintain structural (white and grey matter) and functional integrity and connectivity, cognitive reserve should benefit and behavioral expression of pathological damage should thus be mitigated.

Interpersonal early‐life trauma alters amygdala connectivity and sustained attention performance

“…Beyond modulating and potentially improving treatment outcomes, sustained attention abilities have been associated with multiple aspects of daily living and functional outcomes including academic achievement (Steinmayr, Ziegler, & Träuble, 2010), driver safety and accidents (Edkins & Pollock, 1997; Yanko & Spalek, 2014), and the ability to develop effective social communication skills (Bennett Murphy, Laurie‐Rose, Brinkman, & McNamara, 2007). Additionally, recent developments have suggested that sustained attention ability may provide a gating mechanism that helps to preserve general cognitive abilities during neurodegeneration associated with aging (Robertson, 2013, 2014; Wilson et al., 2013). Collectively, these findings suggest that above and beyond any emotional disturbances that may be associated with early life trauma, concurrent deficits in sustained attention ability can negatively impact multiple facets of an individual's life throughout the lifespan.…”

Successful Cognitive Aging and Health-Related Quality of Life in Younger and Older Adults Infected with HIV

“…A combination of higher education, higher estimated verbal IQ, and higher occupational complexity have been found to comprise what has been termed “cognitive reserve”, which is thought to be the ability to optimize normal cognitive performance 44 , and may serve as a protective factor from the expression of neuropathology 45,46 .…”

Multi-tasking uncovers right spatial neglect and extinction in chronic left-hemisphere stroke patients

“…This is coherent with the vast neuroimaging literature pointing to the existence of early, sensory bottlenecks in information processing -mainly related to short-term memory limits within each modality (Linden, 2007;Marois & Ivanoff, 2005) -and a more general, amodal fronto-parietal network acting as a central information relay and sensibly limiting our efficiency in multitasking (Dux, Ivanoff, Asplund, & Marois, 2006;Spence, 2008;Tombu et al, 2011). Nevertheless, these domain-general, non-lateralized factors (which are also relevant for the notion of cognitive resources/reserve; Stern, 2002) are thought to be associated with right-hemisphere mechanisms (Corbetta & Shulman, 2011;Robertson, 2014).…”