Dopamine- The Buzzword!

Among neurotransmitters, dopamine (DA) has been the focus of extensive scientific investigation (Chinta & Andersen, 2005). It is synthesised by dopaminergic (DAergic) neurons within the brain.

The primary sources of dopamine in the central nervous system are the midbrain DAergic neurons, which are predominantly located in the ventral tegmental area (VTA) and the substantia nigra pars compacta (SNpc). It is widely recognised that the DAergic system plays a fundamental role in regulating behaviour, and its impairments can lead to significant neurological and psychiatric conditions. Its role in coordinating the neural mechanisms associated with learning, memory, and reward-seeking behaviours is vital for adaptive survival (Schultz, 2007). Additionally, dopamine neurotransmission is a key contributor to working memory (Speranza et al., 2021).

The SN and VTA DAergic neurons govern three major neural circuits (Speranza et al., 2021): the nigrostriatal, mesolimbic, and mesocortical pathways, as illustrated in Fig. 1.

Fig.1

The nigrostriatal pathway originates in the SNpc and projects to the dorsal striatum. This pathway is crucial for regulating motor functions and acquiring motor skills. The mesolimbic pathway originates in the VTA and extends dopaminergic axons to several regions, including the PFC, nAc, amygdala, cingulate gyrus, hippocampus, piriform cortex of the olfactory bulb, and insular cortex (Li & Jasanoff, 2020). In the hippocampus, DAergic terminals are implicated in various cognitive functions like learning, working memory, and the formation of long-term memories. Conversely, the mesocortical pathway influences decisions and actions through its connection to the prefrontal cortex, which governs executive functions, planning, and decision making.

Along with its extensive involvement in motor regulation and reward mechanisms, a growing body of evidence highlights the significant role of dopamine in learning and memory, especially in neuroplasticity processes related to memory. Dopamine is a key modulator of hippocampal memory formation, influencing various elements of memory and cognitive function in distinct ways.

The primary source of dopaminergic innervation in the hippocampus remains a topic of debate. Although the VTA has been suggested as the major source of dopamine for the hippocampus (Scatton et al., 1980), recent findings imply that the locus coeruleus may also contribute to dopaminergic signalling in the hippocampus (Kempadoo et al., 2016).

Assessed and Endorsed by the MedReport Medical Review Board