This tract can be seen on the third ventricular surface of the thalamus. Each thalamic projection neuron can exist in one of two basic physiological states "tonic. THALAMUS in most easiest way that any one can understood easily mainly for 1st mbbs students and nursing students. The thalamus physically occupies a central position between the brain stem and the forebrain. It is an important relay point for information going both ways. The thalamus contains about 20 nuclei. Many of these relay sensory information to the cerebral cortex.


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Symptoms of lesions located in the thalamus are closely related to the function of the areas involved. Basal ganglia form a major centre in the complex extrapyramidal motor system, as opposed to the pyramidal motor system corticobulbar and corticospinal pathways.

Basal ganglia thalamus physiology involved in many neuronal pathways having emotional, motivational, associative and cognitive functions thalamus physiology well.

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The striatum caudate nucleus, putamen and nucleus accumbens receive inputs from all cortical areas and, throughout the thalamus, project principally to frontal lobe areas prefrontal, premotor and supplementary motor areas which are concerned with motor planning.

Basal ganglia-thalamo-cortical circuits maintain somatotopic organisation of movement-related neurons throughout the circuit.

Relay nuclei receive very well defined inputs and project this signal to functionally distinct areas of the cerebral cortex. These include the nuclei that relay primary sensations the ventral posterolateral - VPL, ventral posteromedial - VPM, medial geniculate and lateral geniculate nuclei and also the nuclei involved in feedback of cerebellar signals ventral lateral - VL and in feedback of basal gangliar output part of the VL and the ventral anterior nucleus - VA.

The association nuclei are the second type of thalamic nuclei and receive most of their input from the cerebral cortex and project back to the cerebral cortex in the association areas where they appear to regulate thalamus physiology.

The third type of thalamic thalamus physiology are the nonspecific nuclei, including many of the intralaminar and midline thalamic nuclei that project quite broadly through the cerebral cortex, may be involved in general thalamus physiology such as alerting.

Given the various functions of the thalamus, it is not surprising thalamus physiology each of the thalamic nuclei has distinct connections thalamus physiology the cerebral cortex figure 32B.

We will first discuss connections of specific nuclei before discussing the association and nonspecific nuclei.

The VPL relays medial lemniscal and spinothalamic connections to the cerebral cortex.

Functional anatomy of thalamus and basal ganglia.

The VPM receives trigeminothalamic input and relays to the inferior portion of the postcentral gyrus. The lateral and medial geniculate nuclei are specific nuclei that relay thalamus physiology and hearing, respectively.


The lateral geniculate receives retinotopic input via the optic tract from the contralateral homonomous visual thalamus physiology.

This projects in a topographic manner to the primary visual cortex via the optic radiations.

Functional anatomy of thalamus and basal ganglia.

The optic radiations from the upper visual world loop through the temporal lobe white matter on the way to the visual cortex Meyer's loopwhile optic radiations from the lower visual world pass just deep to the parietal lobe.

The medial geniculate receives tonotopically organized auditory afferents from the inferior colliculus thalamus physiology the brachium of the inferior colliculus. This projects to the primary auditory cortex on thalamus physiology superior temporal gyrus transverse gyrus of Heschel.

The VL receives input from the cerebellum, mainly from the dentate nucleus. There is a small input from the basal ganglia to the rostral part of the Thalamus physiology, as well.


The VL projects to the primary motor area, area thalamus physiology, of the precentral gyrus and also has a smaller projection to premotor areas.

The Thalamus physiology is thus involved in motor feedback from the cerebellum and basal ganglia to the cerebral cortex.


The VA nucleus receives most of its input from the basal ganglia especially the medial globus pallidus and substantia nigra, parts reticulata.

This projects to premotor cortex including the supplementary motor area of the frontal lobes and is involved thalamus physiology planning and initiating movements. The centromedian nucleus one of the thalamus physiology nuclei has reciprocal connections with the globus pallidus and with the premotor cortex.