What does thalamus mean in greek

Moreover, on alcohol-hardened brain cuts, Burdach described the internal microarchitecture of the thalamus; he identified the lamina medullaris interna and externa i. Overview of some of the most famous anatomical illustrations of the thalamus and of its macroscopic anatomy and connections.

The posterior surface of the thalamus is depicted along with the posterior thalamic radiation contributing to the corona radiata. Panel f: Reprinted from Theodore Meynert, Psychiatrie. Panel g: Three-dimensional depiction illustrating the main thalamic nuclei and their spatial relationships. Copyright The images are based on a wax model done by Josef Klingler. As mentioned above, in , Burdach 5 became the first to identify the lamina medullaris interna and thus to subdivide the thalamic nuclear mass into superior, internal, and external nucleus cinereus internus, externus, and superior portions based on their position relative to the lamina medullaris interna i.

Similarly, 40 years later, Luys 28 , 29 identified the center anterieur, center moyen, center median, and center posterior portions Fig. At the turn of the 19th century, the scope of microscopic anatomy was further enlarged as a result of significant advancements in histological techniques Nissl staining, 43 , 44 myelin staining, 72 Golgi staining, 18 the Marchi technique 34 , which led to several further studies of the finer cytoarchitecture of the thalamus.

The evidence that only specific parts of the thalamus degenerate following damage of functionally related cortical areas was so remarkable that some authors, such as Meynert in , 65 , 66 started suggesting that thalamic cells should be grouped and named in nuclei only as long as they show corresponding connections. In other words, microscopic topographic subdivision of the thalamus was to be determined based on functional criteria only.

However, this approach was not unanimously accepted, and the subdivision and nomenclature of the thalamic nuclei remained a matter of intense discussions for several decades Fig. Depictions of a coronal section of the thalamus at the level of the posterior commissure. The figure illustrates the discrepancies in nuclear borders and nomenclature reported by the different authors named in the figure.

The differences between the two nomenclatures are due to several factors, the most important probably being that the human thalamus is bigger than that of nonhuman primates.

Nuclear borders are thus much clearer, hence the ease in delimiting them and possibly in finding subdivisions which in the monkey are not so readily identifiable this applies particularly to the pulvinar and to the ventral and lateral thalamic region. For this reason, some of these subdivisions where brought together by Hirai and Jones, unless they could be justified not only through the cytoarchitecture but also by different patterns of fiber connections.

As highlighted by Macchi and Jones in a nice review on this topic, 30 areas with different cytoarchitectonic patterns but the same functional connections are to be understood as a single nucleus and should thus be correspondingly named.

This concept was further extended by Percheron and colleagues, 48 who proposed a totally new subdivision of the so-called motor thalamus based on its afferences pallidal, cerebellar, lemniscal only, thereby revitalizing the old concept of Meynert.

It is thus clear from these considerations that the parceling of the thalamus needs to take both cytoarchitecture and connectivity i. Based on these elements, Morel and associates 40 translated the concepts of Hirai and Jones into an atlas of the thalamus and basal ganglia based on human specimens. They identified the borders of the thalamic nuclei based on multi-architectonic criteria, including Nissl staining and myelin staining, but also based on immunocytochemical identification of the calcium-binding proteins, which have been shown to segregate partly according to functional criteria in humans.

But with the first experimental ablative studies of the first half of the 19th century, it became apparent that the function of the thalamus was much more complex. The introduction of ablative techniques represented a turning point in the understanding of thalamic function. Among the other structures examined, he almost always found atrophy of the contralateral thalamus and compensatory hypertrophy of the ipsilateral one.

This pioneering method was subsequently enriched by von Gudden and his collaborators in their famous work on retrograde degeneration 65 see below. There is evidence of right optic nerve and right thalamus hypertrophy with contralateral atrophy. Right: Drawing of a specimen from a 5-month-old calf brain that was blind in the left eye due to a neonatal lesion.

From Bartolomeo Panizza, Osservazioni sul nervo ottico. He injected zinc chloride colored with aniline blue into the thalamus of dogs, documenting almost constant loss of sensibility. Indeed, as noticed by Roussy in a historical introduction to his work on the function of the thalamus, 52 lesional studies with injection of cytotoxic drugs still were not specific enough, since the injected drug could spread to structures other than those targeted. This evidence obtained in experimental animals was then convincingly supported by anatomo-clinical data, particularly those of Dejerine, 7 who reported the results of several autopsies of stroke patients with thalamic lesions who had developed hemi-anesthesia, thereby clearly and conclusively assigning the thalamus a role in sensory function.

At the turn of the 19th century, thalamic function was thus investigated mainly through experiments with retrograde degeneration, which consolidated its involvement in the somatosensory pathway. For instance, the experimental ablation of cortical areas in newborn rabbits and the subsequent analysis of the degenerated corresponding thalamic nuclei stained with Nissl dye led von Gudden, 65 and later his assistants von Monakow 66 and Nissl, 44 to identify in mammals especially rabbits several thalamo-cortical connections.

In , Nauta and Gygax introduced a new staining technique, 42 which allowed selective visualization of both myelinated and nonmyelinated axon terminals that were undergoing Wallerian degeneration. But such lesions were not often precise for technical reasons, and, as a consequence, the observed pattern of degeneration was also aspecific. As a matter of fact, despite significant technical improvements, all lesional studies, either induced in experimental animals or observed in humans , still suffered from a limited reproducibility.

On top of this, there were limitations inherent to the staining technique. These latter limitations were partly overcome with the development of the anterograde autoradiographic technique in Nonetheless, this innovative method was relatively quickly overtaken by retrograde tracing of horseradish peroxidase 26 from axon terminals to neuron somata, mainly because of the more limited technical demands of the latter technique.

More sensitive fluorescent tracers were then introduced in the late s, in combination with the introduction of immunocytochemical methods. The obvious limitation of these techniques was that, having to rely on a physiological process, they could not be used in the human thalamus but only in that of experimental animals.

Studies of the electrophysiology of the thalamus started to appear in the first half of the 20th century and consisted of electroencephalographic recordings of thalamic activity 3 and the registration of thalamic responses to peripheral stimuli.

The generalizability of data obtained from patients suffering from neurological disease remains limited, however. Moreover, only some portions of the thalamus can be studied with this method. To summarize, the main problem concerning the understanding of thalamic function lies in the fact that most available data derive from studies on nonhuman primates or postmortem human specimens.

In vivo anatomo-functional correlations regarding the thalamus remain particularly difficult in humans. The development of the current knowledge about the function of the human thalamus is the result of a long process over several centuries, which proceeded inextricably intermingled with the increasing accumulation of data about thalamic macro- and microscopic anatomy and with the improvement of the technological tools available. The ex vivo thalamic anatomy on both the macro- and microscale can be considered well understood.

Considerable effort has been recently put into unifying the terminology relative to the internal microscopic architecture and connectivity of the thalamus, a step essential to consistently ascertaining anatomo-functional correlations. The understanding of the function of the thalamus could benefit from ex vivo postmortem studies on human specimens and in vivo studies on nonhuman primates. An appreciation of the function of the human thalamus in vivo is still confronted with significant challenges and technical limitations.

The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper. Conception and design: Serra. Analysis and interpretation of data: Serra, Guida. Approved the final version of the manuscript on behalf of all authors: Serra.

Study supervision: Serra. Arnold F : Tabulae anatomicae: quas ad naturam accurate descriptas in lucem edidit. Nat Neurosci 6 : — , Arch Psychiatr Nervenkr 87 : — , Neurology 38 : — , Leipzig : Dyk , Nature : — , Sagittal cytoarchitectonic maps of the Macaca mulatta thalamus with a revised nomenclature of motor-related nuclei by observations on their connectivity. J Comp Neurol ; — Jones E. The Thalamus.

New York: Plenum Press, CrossRef Google Scholar. The Thalamus of Primates. Handbook of Chemical Neuroanatomy. Amsterdam: Elsevier, ; 1— McCormick DA. Cellular mechanisms of cholinergic control of neocortical and thalamic neuronal excitability. In Steriade M, Biesold B eds. Basal ganglia and cerebellar loops: motor and cognitive circuits. Olszewski J. The thalamus of the Macaca mulatta. The part of the vertebrate brain that lies at the rear of the forebrain. It relays sensory information to the cerebral cortex and regulates the perception of touch, pain, and temperature.

A thallus. Origin of thalamus. Also called thalamium. We could talk until we're blue in the face about this quiz on words for the color "blue," but we think you should take the quiz and find out if you're a whiz at these colorful terms. Words nearby thalamus thalamencephalon , thalamium , thalamo- , thalamocortical , thalamotomy , thalamus , Thalassa , thalassaemia , thalassemia , thalassemia major , thalassic.

How to use thalamus in a sentence This pathway leads from the hippocampus—a brain region that controls learning and memory—to the thalamus , which acts as a sort of sensory information relay station in the brain. Evolution Joseph Le Conte. Buchanan's Journal of Man, May Various.