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Neural pathways

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Corpus Callosum / Colossal Commissure
Connects right and left hemisphere; anterior portion (genu) connects the prefrontal and orbitofrontal regions; central part (body) connecting pre central frontal regions and parietal lobes; posterior porting (splenium / isthmus) connecting occipital lobes.
Raphe nuclei
5HT system; cluster of nuclei found in the brain stem. Their main function is to release serotonin to the rest of the brain. SSRI antidepressants are believed to act in these nuclei, as well as at their targets.
Mesolimbic pathway
DA system; begins in the VTA of the midbrain and connects to the limbic system via the nucleus accumbens, the amygdala, and the hippocampus as well as to the medial prefrontal cortex; widely believed to be a "reward" pathway.
Nigrostriatal pathway
DA system; connects the substantia nigra with the striatum; particularly involved in the production of movement, as part of a system called the basal ganglia motor loop.
Mesocortical pathway
DA system; connects the ventral tegmentum to the cerebral cortex, in particular the frontal lobes; essential to the normal cognitive function of the dorsolateral prefrontal cortex (part of the frontal lobe), and is thought to be involved in cognitive control, motivation, and emotional response.
Extrapyramidal system
A neural network that is part of the motor system that causes involuntary reflexes and movement, and modulation of movement (i.e. coordination); chiefly found in the reticular formation of the pons and medulla.
Tuberoinfundibular pathway
DA system; refers to a population of dopamine neurons in the arcuate nucleus of the mediobasal hypothalamus (the 'tuberal region') that project to the median eminence (the 'infundibular region'); DA released at this site regulates the secretion of prolactin from the anterior pituitary gland; some antipsychotic drugs block dopamine in the tuberoinfundibular pathway, which can cause an increase in blood prolactin levels (hyperprolactinemia). This can cause abnormal lactation (even in men), disruptions to the menstrual cycle in women, visual problems, headache and sexual dysfunction.
Pyramidal tracts
Meaning the corticospinal and corticobulbar tracts; the corticospinal tract conducts impulses from the brain to the spinal cord, the corticobulbar tract carries information to motor neurons of the cranial nerve nuclei, rather than the spinal cord.
Locus coeruleus-noradrenergic system
Efferent projection system of noradrenline throughout the central nervous system; It involves two basic levels of action. First, the system contributes to the initiation and maintenance of behavioral and forebrain neuronal activity states appropriate for the collection of sensory information (e.g. waking). Second, within the waking state, this system modulates the collection and processing of salient sensory information
Dorsolateral prefrontal circuit
Frontostriatal circuit; this circuit is important in executive functions including complex problem solving, learning new information, planning ahead, recalling remote memories, responding with appropriate behavior, and chronological ordering of events.
Orbital frontal circuit
Frontostriatal circuit; this circuit connects the frontal monitoring systems to the limbic system. Dysfunction of this circuit often results in personality change including behavioral disinhibition, emotional lability, aggressive outbursts, poor judgment, and lack of interpersonal sensitivity.
Anterior cingulate circuit
Frontostriatal circuit; this circuit mediates motivated behavior, response selection, error detection, performance and competition monitoring, working memory, and novelty detection. Dysfunction in this circuits lead to decreased motivation including prominent apathy, indifference to pain, thirst or hunger, lack of spontaneous movements, and verbalization.
Motor circuit
Frontostriatal circuit; including the cerebellum, the perirolandic area and the rolandic operculum.
Oculomotor circuit
Frontostriatal circuit; paralleling other motor circuits, including pre central motor fields and basal ganglia, globus pallidus, thalamus, and projects back to the supplementary motor areas (SMA); involved in eye movements.
Association pathways
Type of pathway; connecting cortical regions within the same hemisphere; either anterior-posterior, but can be bidirectional; 5 major ones have been identified
Commissural pathways
Type of pathway; Interhemispheric connections; functional integration of motor, perceptual & cognitive functions; two main pathways
Projection pathways
Type of pathway; connecting the cortex to subcortical structures, such as deep cerebral nuclei, brainstem nuclei, and spinal cord; originate from subcortical nuclei (mainly thalamus) and terminate in the cortex (ascending) or vice versa (descending)
Arcuate fasciculus
Lateral association pathway connecting the perisylvian cortices of the frontal, parietal, and temporal lobe; Left -Language, praxis, and verbal working memory; Right - Visuospatial processing and some aspect of language, e.g. prosody and semantics
Uncinate fasciculus
Ventral association pathway, anterior temporal lobe → medial & lateral orbitofrontal cortex; part of the extended limbic systems; Involved in memory, emotions, and language
Medial association pathway, within the cingulate gyrus (surrounding corpus callosum); basically a circle on the inside of cortices of all lobes; part of the limbic system; Involved in attention, memory & emotion
Inferior longitudinal fasciculus
Ventral association pathway, connecting occipital & temporal lobes; connecting visual areas to temporopolar cortex, amygdala, and hippocampus; involved in object and face perception, reading, visual memory, and language-related functions.
Inferior fronto-occipital fasciculus
Ventral association pathway connecting the inferior and medial occipital lobe to the orbitofrontal cortex; functions poorly understood, thought to be involved in reading, attention, and visual processing.
Anterior commissure
Bilateral connecting of anterior & ventral temporal lobes, including the amygdalae; not fully understood
Posterior commissure
Upper end of the cerebral aqueduct; interconnects the pretectal nuclei, mediating the consensual pupillary light reflex.