2.4 Brain Neurochemistry and Cognitive Performance: Neurotransmitter Systems

Abstract

Though there is no universal definition of cognition, it is widely accepted that it may encompass many different components including: concept formation, mental abstraction, language acquisition, text comprehension, higher linguistic abilities, inference, learning, symbolic reasoning, planning, decision making and metacognition (Metzger, 2011). However, this description may also extend to empathy, procedural memory, introspection and emotional components relevant to the cognitive process. Globally, cognition relies on a balanced function of several neural circuits and pathways modulated primarily by a range of neurotransmitters. The present chapter reviews how altered neurochemical function may result in impaired cognition, with a focus on major classical neurotransmitters. Nonetheless, several other neurotransmitters, mainly small neuropeptides, but also purinergic elements and lipidic endocannabinoids among others, are now known to play relevant roles in cognitive processes. At the end of the present chapter we included a short review of two emerging areas of knowledge in the field of cognitive science: i) the role of gliotransmitteres, referring to the cross-talk between neurons and glial cells, which has previously been underestimated; and ii) the modulation of neurotransmission systems to achieve “neuroenhancement“ or cognitive potentiation. 2.4.1