Brain regions supporting verbal memory improvement in healthy older subjects

Abstract

Despite growing interest in developing cognitive training interventions to minimize the aging cognitive decline process, no studies have attempted to explore which brain regions support the application of semantic strategies during verbal memory encoding. Our aim was to investigate the behavioral performance and brain correlates of these strategies in elderly individuals using fMRI in healthy older subjects. Method: Subjects were scanned twice on the same day, before and after, directed instructions to apply semantic strategies during the encoding of word lists. Results: Improved memory performance associated to increased semantic strategy application and brain activity in the left inferior and middle and right medial superior prefrontal cortex were found after the directed instructions. There was also reduced activation in areas related to strategy mobilization. Conclusion: Improved memory performance in older subjects after the application of semantic strategies was associated with functional brain reorganization involving regions inside and outside the typical memory network.Keywords: older subjects, semantic strategies, fMRI, episodic memory. RESUMOApesar do crescente interesse em intervenções de treinamento cognitivo para minimizar o declínio cognitivo do envelhecimento, nenhum estudo explorou quais regiões do cérebro estão relacionadas à aplicação de estratégias semânticas durante a codificação da memória verbal. Nosso objetivo foi investigar o comportamento e correlatos cerebrais associados a essas estratégias usando fMRI em idosos saudáveis. Método: Os sujeitos foram examinados no mesmo dia, antes e depois, de instruções dirigidas para aplicar estratégias semânticas durante a codificação de palavras. Resultados: Melhora da memória relacionada ao uso de estratégias semânticas e aumento da atividade no córtex prefrontal inferior e medial esquerdo e medial superior direito foram encontrados após as instruções. Também houve redução de ativação em áreas de mobilização de estratégias. Conclusão: A melhora da memória em idosos após o uso de estratégias semânticas estava associada à reorganização cerebral funcional envolvendo regiões dentro e fora da rede de áreas cerebrais típicas da memória.Palavras-chave: idosos, estratégias semânticas, fMRI, memória episódica.The aging process is associated with progressive decline in cognitive abilities such as memory, attention and executive function 1,2,3 . Therefore, older subjects commonly experience functional and cognitive losses which can affect quality of life, social interaction, and occupational performance. More recently, there has been a great concern with benign cognitive decline and the risk for developing mild cognitive impairment (MCI) or dementia progression. As a consequence, there has been growing interest to explore non-pharmacological clinical interventions, particularly cognitive training, to minimize this process or improve some cognitive skills in older adults 4 . Episodic memory is the most commonly affected type of memory in aging 5,6 . The...

Effects of aging on value-directed modulation of semantic network activity during verbal learning

“…In a number of prior studies (e.g., Wagner et al, 1998; Savage et al, 2001; Paller and Wagner, 2002; Addis and McAndrews, 2006; Kirchhoff and Buckner, 2006; Miotto et al, 2006), activation of left inferior prefrontal regions during encoding in young adults has been associated with the use of effective semantic strategies, as well as with a concomitant increase in performance on a subsequent memory test. More recent work (Kirchhoff et al, 2012; Miotto et al, 2014) has shown that older adults who are trained to engage semantic encoding strategies also show increased activity in left IFG, among other regions, during encoding. It is notable that when we compare the six activation peaks in left IFG from across those two studies (transformed from Talairach to MNI space as necessary; Lancaster et al, 2007) with our whole-brain analysis examining the correlation between value effects during encoding and selectivity index (see Fig.…”

Interventional programmes to improve cognition during healthy and pathological ageing: Cortical modulations and evidence for brain plasticity

“…In fact, interventional programmes based on CI and PE frequently last from several months to one year, which would be a time period more than sufficient to promote the activation of neuroplasticity mechanisms. Nevertheless, neural activity changes have also been observed after one or only a few sessions of CT in healthy elderly subjects (Belleville et al, 2011;Kirchhoff et al, 2012;Miotto et al, 2014;Nyberg et al, 2003) and cognitively impaired patients (Belleville et al, 2011;Hampstead et al, 2011;Hampstead et al, 2012a). Likewise, neural activity changes have been observed after a single session or only a few sessions of TMS or tES in healthy elderly subjects (Holland et al, 2011;Lindenberg et al, 2013;Sole-Padulles et al, 2006) and cognitively impaired patients (Devi et al, 2014;Khedr et al, 2014;Meinzer et al, 2014).…”

Left caudal middle frontal gray matter volume mediates the effect of age on self-initiated elaborative encoding strategies

“…Instructing or training older adults to use elaborative encoding strategies can increase their use of those strategies and improve their memory performance (Kirchhoff et al, 2012; Miotto et al, 2014; Naveh-Benjamin et al, 2007). Thus, age differences in spontaneous encoding strategy use are most likely due to age differences in the ability to self-initiate complex effortful strategies rather than impairment in older adults’ ability to effectively use them.…”