Etiology of Geophagia
Anil Gupta in Geophagia, 2019
Dopaminergic pathways are the neuronal networks that connect one portion of brain with another. They are composed of axons of dopaminergic neurons in the brain. There are three main types of dopaminergic pathways: nigrostriatal, mesolimbic, and mesocortical pathways. The mesolimbic pathway is primarily implicated in reward behavior. The cell bodies of the mesolimbic pathway are located in the ventral tegmental area at the floor of the midbrain (Malenka et al. 2009). The axons descend from the ventral tegmental area to the ventral corpus striatum, which is located in the forebrain. The ventral corpus striatum is the chief component of the reward system of the brain (Yager et al. 2015). It is composed of the nucleus accumbens and olfactory tubercle (Ferré et al. 2010; Taylor et al. 2013).
Increasing physiologic readiness to improve functional independence following neurotrauma
Mark J. Ashley, David A. Hovda in Traumatic Brain Injury, 2017
Lack of follow-through with therapeutic or medication interventions in medical populations has been largely described as noncompliance, a term that implies the willful refusal to adhere to an established treatment plan. Although deliberate insubordination may occur in provider-patient relationships, the roles of initiation and planning deficits following brain injury merit specific attention. Well-described dopaminergic pathways are responsible for initiation of volitional activity, motor or behavioral, in humans.57 Over the first two decades of neurodevelopment, these circuits progressively branch, prune, and mature in a manner that parallels the diminishing degree of external structure, support, and supervision required by parents, teachers, coaches, and others as the child grows up. As a result, the degree of oversight required to ensure antibiotic medication compliance for an otitis media in a 5-year-old child is far more extensive than the same illness would require in a 15-year-old.
Exercise, neurotransmission and neurotrophic factors
Romain Meeusen, Sabine Schaefer, Phillip Tomporowski, Richard Bailey in Physical Activity and Educational Achievement, 2017
Dopaminergic cell groups are found in the mesencephalon, the diencephalon and the telencephalon. The main ascending dopaminergic pathways include the nigrostriatal tractus, the ventral mesostriatal (or mesolimbic) pathway and the tuberoinfundibular system, which arises from cells located in the diencephalon (Meeusen & De Meirleir, 1995). The rate-limiting step in the biosynthesis of DA is the hydroxylation of tyrosine to dihydroxyphenylalanine (DOPA) by the enzyme tyrosine hydroxylase. The majority of tyrosine hydroxylase is located in catecholamine nerve terminals. DOPA is decarboxylated to DA by the enzyme DOPA decarboxylase (aromatic amino acid decarboxylase). The activity of this enzyme is not rate-limiting in the synthesis of the catecholamines, and is therefore no regulating factor in their formation. In normal physiological conditions DA is first metabolized to 3,4-dihydroxyphenylacetic acid (DOPAC) by monoamine oxidase (MAO) and aldehyde oxidase. DOPAC is then further metabolized into homovanillic acid by catechol-O-methyltransferase (COMT) (Meeusen & De Meirleir, 1995).
Amantadine and memantine: a comprehensive review for acquired brain injury
Published in Brain Injury, 2020
Heather M. Ma, Ross D. Zafonte
A third proposed mechanism for increasing the level of severely injured patients’ clinical arousal and awareness is through targeted dopamine enhancement. The theoretical basis of this concept involved pharmacologically targeting three of the four major dopaminergic pathways in the brain (15): The mesolimbic pathway, associated with motivation, learning, and memory.The nigrostriatal pathway, involved in initiation and velocity of movement.The mesocortical pathway, involved in motivation or activation, planning, and temporal organization, as well as associated with cortical tone and attention.
The influence of syringic acid treatment on total dopamine levels of the hippocampus and on cognitive behavioral skills
Published in International Journal of Neuroscience, 2022
Eren Ogut, Guven Akcay, Fatos Belgin Yildirim, Narin Derin, Mutay Aslan
The hippocampus plays a pivotal role in the reinforcement and encoding of information in short and long-term memory, spatial memory, and recognition memory [1]. The ventral hippocampus (VH) receives the dopaminergic pathways from the ventral tegmental area and the dorsal hippocampus (DH) [1]. Dopamine (DA) increases attention to evident properties of the environment in spatial memory, and the innervation of DA within the VH can contribute to incentive salience and motivational learning [1]. Dopaminergic signaling is established as executing a leading role in novelty-associated modulation of learning and memory [2]. It is claimed that DA affects plasticity, synaptic transmission, and network activity in the hippocampal circuitry [2]. The manipulation of hippocampal D1/5 receptors indicates the source of DA from the ventral tegmental area or DA release from noradrenergic fibers [2]. The functions of DA are listed as follows: executive functions take part in cognitive motor control, neuromodulation, arousal, reinforcement, motivation, and the reward system [3,4]. Dopamine pathways are responsible for the motivational component of reward-motivated behavior, and the anticipation of most types of rewards increases the level of DA. Also, as a part of the neuromodulator system, these pathways are involved in motor control and in controlling the release of hormones [3,4]. Short term working memory is a highly dynamic process of short-time encoding of information to adjust subsequent behavior, and the dopaminergic system in the hippocampus has been identified as being involved in the modulation of working memory [5].
Cellular and circuit mechanisms of olfactory associative learning in Drosophila
Published in Journal of Neurogenetics, 2020
Tamara Boto, Aaron Stahl, Seth M. Tomchik
In addition to the role that DANs play in valence/US processing, one subset plays a unique role in memory, driving plasticity in the MB and modulating memory strength without encoding valence. PPL2ab DANs innervate the dendritic MB region in the calyx (among other brain regions) (Kuo et al., 2015; Mao & Davis, 2009) (Figure 1(B)). Pairing stimulation of the PPL2ab neurons with odor presentation enhances odor-evoked activity in MB γ neurons; this effect is associated with increased aversive memory performance (Boto, Stahl, Zhang, Louis, & Tomchik, 2019). These results imply that dopamine acting on MB neurons can either drive a valence signal (US) or act as a gain control mechanism, modulating the strength of the memory. The behavioral outcome appears to depend on which dopaminergic pathway is activated and which spatial MB compartment the neurons innervate. This compartmental topography and division of labor represent a fundamental organizing principle on which the MB operates (Figure 1(A,B)).
Related Knowledge Centers
- Cognition
- Mesocortical Pathway
- Mesolimbic Pathway
- Motivation
- Neuroendocrine Cell
- Projection Fiber
- Brain
- Executive Functions
- Reward System
- Nigrostriatal Pathway