Brain network dynamic during short-term memory binding: a study across the lifespan
To identify the brain networks supporting short term memory binding functions and their changes as we age. Short-term memory binding has proved insensitive to normal ageing. This is the only integrative memory function we have to remain preserved across the lifespan. The underpinnings of this lack of vulnerability remain unknown. We are developing novel electrophysiological methods to characterise the network changes that support this preserved ability.
Electrophysiological assessment of interhemispheric transfer time
The electrophysiological assessment of interhemispheric transfer time (IHTT) investigates how efficiently once can transfer basic visual information between the hemispheres of the brain via the splenium of the corpus callosum (CC). While the splenium of the CC is relatively preserved in healthy normal ageing (Bhagat & Beaulieu, 2004), those with Alzheimer’s Dementia are likely to experience a decline in its connectivity (Rose et al., 2000). We wish to test whether IHTT may differentiate between healthy older adults and adults with Mild Cognitive Impairment.
Optimal Low-density EEG montage to detect mild cognitive impairment in ambulatory settings
Aims: To identify the minimal number of electroencephalograph (EEG) sensors that can help distinguish between elderly people with mild cognitive impairment and healthy older adults during memory binding, a task that has proved sensitive and specific for Alzheimer’s disease (AD). Methods: Alzheimer’s disease disconnects brain regions necessary to process complex events in memory such as shape-colour bindings. Such an effect is apparent during task performance and can also be measured using EEG, a non-invasive technique which uses wires attached to the scalp to collect the brain’s electrical activity. Currently, EEG relies on extended arrays of sensors connected to large recording devices. This limits its use outside laboratories. The complexity of such settings can be reduced by focusing on a subset of the most informative EEG sensors. Such sensors would collect activity that unequivocally informs about the presence of AD. We hypothesise that the EEG activity associated to memory binding will achieve this aim. Outcomes: The minimal EEG setting will reveal AD-related changes that account for poor memory binding performance before the disease becomes clinically apparent. Such a portable system will be detached from laboratories, increasing access to this novel methodology via its introduction in community based settings.
Enhancing memory binding abilities across age using tDCS
Recent studies suggest that transcranial Direct Current Stimulation (tDCS) can enhance VSTM capacity (Tseng et al., 2012). Binding is a cognitive construct that operates in VSTM but can be dissociated from other VSTM functions (Parra, Della Sala, Logie, & Morcom, 2014; Parra et al., 2010; Parra, Abrahams, Logie, & Della, 2010; Parra, Sala, Logie, & Abrahams, 2009). Considering its pivotal role in higher order cognitive functions and its vulnerability to abnormal variants of ageing such as dementia due to Alzheimer’s disease, it would be relevant to investigate if binding functions can also be enhanced using brain electrical stimulation. To this aim, we will apply transcranial Direct Current Stimulation (tDCS) to regions of a brain network located over the frontal and parietal areas of the left hemisphere which have proved to be relevant for VSTM binding (Parra et al., 2014). In detail, participants will perform the VSTM binding task both before (baseline) and during stimulation (experimental condition). Participants’ VSTM capacity will be initially identified using classical memory capacity procedures (Rouder, Morey, Morey, & Cowan, 2011). We will collect behavioural responses (accuracy, hits, false alarms and response times) during task performance (i.e., dependent variables). Baseline variables will be compared between the two groups to ensure they are matched. The aim of this study is to investigate if binding functions carried out in visual short-term memory (VSTM) can be enhanced as to improve performance of healthy subjects. Considering that such a function declines dramatically in older adults with cognitive impairment (e.g., MCI) who are at the highest risk of developing dementia (Koppara et al., 2015), proving this hypothesis valid would help design non-pharmacological interventional aimed at boosting memory function known to be relevant to everyday life functioning.
Network Theory concepts to EEG signal data of patients with amnestic mild cognitive impairment (aMCI)
This research focuses on developing and applying novel Network Theory concepts to EEG signal data of patients with amnestic mild cognitive impairment (aMCI). The aim is to find conclusive evidence of changes in the functional connectivity of brain signals predicting the development Alzheimer's disease.
Electrophysiological correlates of emotional processing in normal individuals and in those with neuropsychiatric, psychosocial, or developmental disorders
This study aims to investigate the contribution of mechanisms of attention and the time course of such mechanisms to the emotional processing bias in both typically developing subjects and in those with developmental or acquired disorders. It focuses on the neural correlates of such processing bias. To this aim have devised a comprehensive methodological approach which incorporates behavioural, electrophysiological, and neuropsychological assessment, all link to emotional processing. This methodology is being used to assess individuals with ASD, chronic exposure of violence (war conflict zones) and people with different cultural backgrounds.