Other Deep Gray Nuclei



Other Deep Gray Nuclei


Lubdha M. Shah, MD



IMAGING ANATOMY


Overview



  • Red nucleus (RN)



    • Caudoventral magnocellular part (mcRN) and rostrodorsal parvocellular part (pcRN); latter represents majority of nuclear volume


    • Afferents from cerebral cortex on their distal dendrites and from deep cerebellar nuclei on their proximal dendrites and perikarya


    • mcRN mainly connected to motor and premotor cortices (arm and leg areas) and cerebellar interposed nuclei



      • Gives rise to crossed rubrospinal tract to spinal motor neurons and interneurons of distal, particularly flexor, muscles


      • Shows movement-related activity that correlates with duration, amplitude, and velocity of independent distal movements


    • pcRN receives afferents from primary, frontal, and supplementary motor cortices, accounting for 90% of total corticorubral afferents arising from cortical sublamina V



      • Projects onto bulbar olivary complex via central tegmental tract


      • Main efferent is represented by the inferior olive


      • Receives fibers from parts of cingulate and parietal cortices


      • May be involved in complex motor coordination rather than simple movements or may even be involved in nonmotor functions


  • Basal forebrain consists of several paleopallial structures, including substantia innominata, diagonal gyrus, and paraterminal gyrus



    • Substantia innominata and diagonal gyrus located in posterior 1/2 of anterior perforated substance


    • Paraterminal gyrus is on medial aspect of diagonal gyrus and posterior to subcallosal area


    • Nucleus basalis of Meynert (NB)



      • Within substantia innominata


      • Large cholinergic neurons


      • Projections from NB to cerebral cortex


    • Nucleus of the diagonal band of Broca in diagonal gyrus


    • Medial and lateral septal nuclei in paraterminal gyrus



      • Cholinergic projections from nucleus of diagonal band of Broca and septal nuclei to hippocampal formation


  • Locus coeruleus (LC)



    • Located adjacent to floor of 4th ventricle in rostral pons and extends into midbrain to level of inferior colliculi



      • LC cells are most densely populated at level of trochlear nucleus


      • Largest group of noradrenergic neurones in central nervous system


    • Excitatory projections to



      • Majority of cerebral cortex


      • Cholinergic neurons of basal forebrain


      • Cortically projecting neurons of thalamus


      • Serotoninergic neurons of dorsal raphe


      • Cholinergic neurons of pedunculopontine and laterodorsal tegmental nucleus


    • Inhibitory projections to sleep-promoting GABAergic neurons of basal forebrain and ventrolateral preoptic area


    • Implicated in modulating attentional states


    • Regulation of arousal and autonomic activity



      • Direct projections to spinal cord


      • Projections to autonomic nuclei: Dorsal motor nucleus of vagus, nucleus ambiguus, rostroventrolateral medulla, Edinger-Westphal nucleus, caudal raphe, salivatory nuclei, paraventricular nucleus, amygdala


      • LC activation produces increase in sympathetic activity and decrease in parasympathetic activity via these projections


  • Substantia nigra (SN): Pars compacta (SNPc) and pars reticulata (SNPr)



    • Part of A9 dopaminergic (DA) system



      • A9 DA fibers vary in size (20-40 µm) and extend from medial lemniscus to lateral cerebral peduncles


    • Sensorimotor areas of striatum project to ventrolateral pallidum and ventrolateral SNPc cell columns


    • Projections from central striatum terminate more centrally in both pallidum and ventral densocellular SNPc


    • Ventral striatum projects topographically into ventral pallidum, ventral tegmental area, and densocellular SNPc


    • Pars compacta produce dopamine → increased motor activity


  • Ventral tegmental area (VTA)

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Sep 18, 2016 | Posted by in MAGNETIC RESONANCE IMAGING | Comments Off on Other Deep Gray Nuclei

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