Joana Cabral

 

I have a PhD in Theoretical and Computational Neuroscience, currently working as postdoctoral researcher at the Life and Health Sciences Research Institute of the University of Minho in Portugal and a visiting researcher at the Hedonia Research Group at the Department of Psychiatry of the University of Oxford, UK

My main interest is to investigate the fundamental principles underlying brain function. In other words, I am curious about the most primitive biophysical mechanisms at the genesis of coordinated brain activity, ultimately leading to our thoughts and actions. In my research, I test hypothetical mechanistic scenarios using analytical and numerical methods to investigate fundamental brain mechanisms from in silico network models. 

 

Brain Functional Networks in Healthy aging and Parkinson's disease

The archetype of an old wise man has been present through times and cultures as an elder figure distinguished for its wisdom and sound judgement, inspiring our dreams of reaching a bright and enlightened old age. However, how such elders achieve to fight the apparently natural cognitive decline associated with old aging remains unclear. As a matter of fact, healthy aging is generally accompanied by a decline in several cognitive domains, such as episodic memory, memory retrieval, attention or task switching. Despite this, age-related cognitive decline is marked by high inter-individual variability, with some subjects being able to maintain impressive cognitive performance until a very advanced age. In a time where modern medicine pushes life expectancy to the limits of our body, one of the current challenges in geriatric cognitive neuroscience it to understand the root of cognitive decline and eventually dissociate it from the aging process.
We analysed brain activity from 98 healthy adults aged between 50 to 91 years old, who underwent neuropsychological assessment and were previously categorized as being among the best or among the worst performers in a cohort study of >1000 subjects from the Braga and Guimarães region (SWITCHBOX 2011-2015 FP7-HEALTH-259772).  We used a novel approach to detect the functional networks emerging transiently in functional MRI at rest and characterized them in terms of lifetime, probability of occurrence and switching profiles. We found that poorer cognitive performance is associated with weaker temporal similarity together with altered switching between functional networks [1]. These results provide new evidence linking the switching dynamics of brain activity during rest with cognitive performance in later life, reinforcing the functional role of resting-state activity for effective cognitive processing.

 

We further compared these healthy controls with 12 age-matched patients with Parkinson's disease implanted with Deep Brain Stimulation (DBS), from a collaboration with the UCL, London. To date, deep brain stimulation (DBS) has been applied to over 150,000 patients to alleviate tremor symptoms in Parkinson’s disease – an incurable condition affecting more than 6 million people worldwide characterized by episodic tremor. DBS consists in delivering electrical high-frequency stimulation into deep brain structures through implanted microelectrodes. Despite its verified efficacy, the underlying biophysical mechanisms of DBS remain unclear. In our study, we found that when DBS is turned ON, it induces a significant restoration of global dynamics towards healthy values [2], in line with the prevailing theory that DBS acts by rebalancing the spontaneous switching dynamics between functional networks.

 

[1] Cabral, Joana, et al. "Cognitive performance in healthy older adults relates to spontaneous switching between states of functional connectivity during rest." Scientific Reports 7.1 (2017): 5135.
[2] Saenger VM, Kahan J, Foltynie T, Friston K, Aziz TZ, Green AL, Hartevelt TJ, Cabral J, Stevner AB, Fernandes HM, Mancini L. "Uncovering the underlying mechanisms and whole-brain dynamics of deep brain stimulation for Parkinson’s disease". Scientific Reports. 2017 Aug 29;7(1):9882.