**1. Introduction**

Advances in medicine over the last century have resulted in a considerable increase in human life expectancy. Despite this positive outcome, with increase in age, comes a decline of metabolic and immune functions with impact on the cognitive functions. Although, some decline in cognitive function does occur with normal aging, there is also an increased age-associated risk of neurodegenerative disorders such as Alzheimer's disease (AD) [1]. At the same time, it highlights the need for a more comprehensive understanding of how different aspects of lifestyle such as physical exercise, meditation, musical experience, and diet may influence brain disorders in a preventative manner, affecting long-term neural function that affects cognitive performance [2]. In relation to the diet, flavonoids have been described as promising plant-based bioactives capable of modulating different aspects of neuroplasticity, resulting in improvements in memory in both rodents [2] and humans [3, 4]. For example, flavonoids have been correlated with their ability to modulate the phosphorylation state of intracellular proteins by the activation or inhibition of phosphoinositide 3-kinase (PI3K), protein kinase C (PKC), mitogenactivated protein kinase (MAP), CAMP responsive element binding protein 1 (CREB-1), growth associated protein 43 (GAP-43), brain-derived neurotrophic factor (BDNF), or to alter expression of N-methyl d-aspartic acid (NMDA) receptors (NMDARs), GABAA receptors (GABAARs), and 5-HT receptors (5-HTRs) [5, 6]. In addition, flavonoids can modulate epigenetic modifications [7]. These mechanisms are critical for the neuroplasticity and they are also related with inflammatory processes in the brain.

The aim of this chapter is to highlight the potential of flavonoid-rich food, flavonoid-rich extract, and medicinal plants that act as modulators of neuroplasticity in the central nervous system of mammals. We provide an outline of the neuroplasticity and how flavonoids affect this mechanism, and we will also describe their interaction in the neuroinflammation mechanism that affects the cognition. It will highlight the probable mechanisms that flavonoids promote neuroprotective effect in aging.
