Medial dorsal nucleus

The medial dorsal nucleus (or dorsomedial nucleus of thalamus) is a large nucleus in the thalamus.

Not to be confused with Dorsomedial hypothalamic nucleus.
Medial dorsal nucleus
Thalamic nuclei
Details
Identifiers
Latinnucleus mediodorsalis thalami
MeSHD020645
NeuroNames312
NeuroLex IDbirnlex_1543
TA98A14.1.08.622
TA25681
FMA62156
Anatomical terms of neuroanatomy

It is believed to play a role in memory.[1]

Structure

It relays inputs from the amygdala and olfactory cortex and projects to the prefrontal cortex and the limbic system and in turn relays them to the prefrontal association cortex. As a result, it plays a crucial role in attention, planning, organization, abstract thinking, multi-tasking, and active memory.

The connections of the medial dorsal nucleus have even been used to delineate the prefrontal cortex of the Göttingen minipig brain.[2]

By stereology the number of brain cells in the region has been estimated to around 6.43 million neurons in the adult human brain and 36.3 million glial cells, and with the newborn having quite different numbers: around 11.2 million neurons and 10.6 million glial cells.[3]

Function

Pain processing

While both the ventral and medial dorsal nuclei process pain, the medial dorsal nucleus bypasses primary cortices, sending their axons directly to secondary and association cortices. The cells also send axons directly to many parts of the brain, including nuclei of the limbic system such as the lateral nucleus of the amygdala, the anterior cingulate, and the hippocampus. This part of the sensory system, known as the non-classical or extralemniscal system is less accurate, and less detailed in regards to sensory signal analysis. This processing is known colloquially as "fast and dirty" rather than the "slow and accurate" system of classical or lemniscal system. This pathway activates parts of the brain that evoke emotional responses.

Saccadic efference copy

This nucleus is also presumed to play a role in monitoring internal movements of the eye. Specifically, its function is to relay the information about how the eyes will be moved (efference copy, also known as corollary discharge) from the superior colliculus to the frontal eye fields (FEF) in order to aid the neurons in FEF to change their receptive fields to where the visual stimuli will appear after the saccade.[4]

Clinical significance

Damage to the medial dorsal nucleus has been associated with Korsakoff's syndrome.[5]

Additional images
  • Thalamus
  • Thalamus

References
  1. Li XB, Inoue T, Nakagawa S, Koyama T (May 2004). "Effect of mediodorsal thalamic nucleus lesion on contextual fear conditioning in rats". Brain Res. 1008 (2): 261–72. doi:10.1016/j.brainres.2004.02.038. PMID 15145764.
  2. Jacob Jelsing; Anders Hay-Schmidt; Tim Dyrby; Ralf Hemmingsen; Harry B. M. Uylings; Bente Pakkenberg (2006). "The prefrontal cortex in the Göttingen minipig brain defined by neural projection criteria and cytoarchitecture". Brain Research Bulletin. 70 (4–6): 322–336. doi:10.1016/j.brainresbull.2006.06.009. PMID 17027768.
  3. Maja Abitz; Rune Damgaard Nielsen; Edward G. Jones; Henning Laursen; Niels Graem & Bente Pakkenberg (2007). "Excess of Neurons in the Human Newborn Mediodorsal Thalamus Compared with That of the Adult". Cerebral Cortex. 17 (11): 2573–2578. doi:10.1093/cercor/bhl163. PMID 17218480.
  4. Sommer, Marc A.; Wurtz, Robert H. (2008). "Brain circuits for the internal monitoring of movements". Annual Review of Neuroscience. 31: 317–338. doi:10.1146/annurev.neuro.31.060407.125627. ISSN 0147-006X. PMC 2813694. PMID 18558858.
  5. Kopelman, Michael D. (2015-07-01). "What does a comparison of the alcoholic Korsakoff syndrome and thalamic infarction tell us about thalamic amnesia?". Neuroscience & Biobehavioral Reviews. The Cognitive Thalamus. 54: 46–56. doi:10.1016/j.neubiorev.2014.08.014. ISSN 0149-7634. PMID 25218758.
  • Aage R. Moller "Pain: Its anatomy, physiology and treatment" 2012
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