6.8 Major Fiber Tracts & Neuroanatomy

Alcohol

• (Segobin, 2015): Frontocerebellar circuit (FCC): middle cerebellar peduncle, superior cerebellar peduncle. Papez circuit (PC): cingulum, fornix
• These are the tracts that are believed to offer less variability in terms of specificity to the PC and FCC, respectively, having a lower involvement in fibers connecting other parts of the brain or involved in other circuitry.
• (Durkee, 2013): fornix, anterior commissure, genu of the corpus callosum, splenium of the corpus callosum, right inferior fronto-occipital fasciculus (IFO), bilateral dorsal cingulum bundle.

Cocaine: corpus callosum (reference)

Meth: (Alicata, 2009) right frontal WM, basal ganglia

Heroin: right orbito-frontal WM, bilateral temporal WM, right parietal WM (reference?). 

(Wang, 2011) reduced FA in left genu of CC, increased MD in left splenium of CC

Nicotine (Smoking):

• (Yu, 2015) increased FA, increased AD, and decreased RD in right posterior limb of the internal capsule, the right external capsule, the right superior corona radiata.
• (Wang, 2009) frontal WM (together with decreased NAA), (Kochunov, 2013) genu of corpus callosum
• Basal ganglia is not a WM, but an aggregated gray matter region.

Cocaine: (Ma, 2015) genu, body, and splenium of corpus callosum, (Bell, 2011) decreased FA in left anterior callosal fibers, left genu of CC, right superior longitudinal fasciculus, right callosal fibers, and bilateral superior corona radiata.

Neuroanatomy

• Fornix: carry signals from hippocampus to mammiliary bodies to anterior nuclei of thalamus; part of limbic system; involve in long-term memmory.
• Cingulum bundle: cingulate gyrus to entorhinal cortex; part of limbic system; involve in learning and correcting mistakes.
• Medial forebrain bundle: a tract containing fibers from basal olfactory region, periamygdaloid region, septal nuclei, brainstem, ventral tegmental area, mesolimbic pathway.