Mamillothalamic Tract

Recollection is mediated by the anterior thalamic nucleus (AN), the mamillothalamic tract (MTT) and the hippocampus.  

The two lesions are isolated and remarkably centered with the mamillothalamic tract. We suggest the symptoms are caused by the addition of the two lesions interrupting the mamillothalamic tracts. This is the second clinico-pathological observation of a persistent amnestic syndrome secondary to a bilateral lesion of the mamillothalamic tract..  

In axonal tracts, ferroportin immunoreactivity was high in fibers of the internal capsule, fimbria, mamillothalamic tract and the habenulo-interpedunculo pathway.  

These results indicate that the whole of the inferotemporal cortex-anterior thalamic circuit, which passes via the hippocampus, fornix, mamillary bodies and mamillothalamic tract, is essential for the topographical analysis of information about specific objects in different positions in space.  

MR images showed that lesions involved the genu of the internal capsule, the anteroventral nucleus, the lateroventral nucleus, intralaminar nuclei, the mamillothalamic tract and the region around the ventral thalamus.  

Atrophy of the fornix, mamillary body, mamillothalamic tract (MTT), and thalamus ipsilateral to the epileptic focus was demonstrated on MR images in 14.7, 17.6, 8.8, and 11.8% of the 34 patients, respectively.  

Computed tomography and magnetic resonance imaging revealed cerebral haemorrhage in the right thalamus involving the ventral anterior nucleus, medioventral nucleus, mamillothalamic tract, internal medullary lamina, and mediodorsal nucleus.  

We reviewed the MRI studies of 15 patients with probable MTS, seeking changes in the fornix, mamillary body, mamillothalamic tract, thalamus and cingulate and parahippocampal gyri.  

Magnetic resonance imaging emphasized involvement of the anterior group of thalamic nuclei, the mamillothalamic tract, and the anterior part of the internal medullary lamina, with structural sparing of the dorsomedial and ventrolateral nuclei.  

The hitherto reported cases of the genu infarcts that showed memory disturbance had the lesion involving both the inferior thalamic peduncle and its nearby mamillothalamic tract.  

Later, M2 expression is found in association with the corpus callosum, hippocampal commissure, fimbria, optic nerve, stria medullaris, mamillothalamic tract and habenulopeduncular tract.  

PURPOSE: To demonstrate the normal and abnormal appearance of the mamillothalamic tract (MTT) on cranial magnetic resonance (MR) images.  

These findings suggest that functional involvement of the frontal and temporal lobe connections with the dorsomedial nucleus, anterior nucleus, and the mamillothalamic tract in the anteromedial part of thalamus were responsible for the prolonged antegrade amnesia.  

The left rostral part of the thalamus appears to be responsible for his TGA, due probably to an interference of the mamillothalamic tract, ventroamygdalofugal pathway or dorsal noradrenergic bundle..  

Rabbits with bilateral transecting lesions of the mamillothalamic tract, control (tract-sparing and sham) lesions, or no lesions, and chronic, fixed-position anterior ventral (AV) and medial dorsal (MD) thalamic and posterodorsal subicular complex unit recording electrodes were trained to step in an activity wheel in response to a 0.5 sec tone (CS+) in order to avoid a brief foot shock. Behavioral acquisition was significantly retarded in rabbits with mamillothalamic tract transection compared to controls. mamillothalamic tract transection abolished and control lesions attenuated AV thalamic discriminative training-induced activity (i.e., development with training of greater discharges in response to the CS+ than to the CS-). mamillothalamic tract afferent information flow is thus essential for AV thalamic discriminative training-induced activity, excitatory training-induced activity, tone-elicited discharges and maintenance of conditioned avoidance responses. The effects of the control lesions suggested that afferents which course in parallel with and near the mamillothalamic tract may contribute to AV thalamic spontaneous activity and excitatory training-induced activity..  

In addition, there was central pontine and extensive extrapontine myelinolysis involving the lateral and medical geniculate bodies, the thalamus, internal capsule, fornix, mamillothalamic tract, white matter bundles in the caudate and pallidum, the oculomotor nuclei and the foliar white matter of the cerebellum.  

On MRI, the infarct was limited to the left anterior thalamic nuclei and the adjacent mamillothalamic tract.  

The damage implicated the ventral anterior nucleus, the mamillothalamic tract, and the rostroventral internal medullary lamina.  

Persistent amnesia was observed only when the dominant anterior nucleus or mamillothalamic tract was damaged.  

Several fiber tracts were also revealed, i.e., the lateral olfactory tract, mamillothalamic tract, fasciculus retroflexus, optic tract, and stria medullaris.  

A cluster composed of small DA- and DOPA-IR cells was identified in the area ventral to the mamillothalamic tract equivalent to rat A13c TH-IR cell group.  

Our findings were (1) patients develop amnesia when infarctions are located anteriorly; (2) in patients with amnesia, the lesions can be small and strategically located, probably interfering with both hippocampal-related neural structures such as the mamillothalamic tract, and amygdala-related neural structures such as the ventroamygdalofugal pathway; and (3) a specific component of the latter is situated lateral but immediately adjacent to the mamillothalamic tract in the monkey, enabling both structures to be damaged bilaterally by small mirror image lesions.  

The principal thalamic and hypothalamic structures implicated in mnemonic information processing are the mediodorsal nucleus of the thalamus, the pulvinar, anterior thalamus, and laterodorsal nucleus, the mamillary body, and the mamillothalamic tract and internal medullary lamina. Such an approach revealed that the contributions of the two fiber systems mentioned above, mamillothalamic tract and internal medullary lamina, might be more important in processing information long-term than had been acknowledged previously and might be more important than that of the nuclear masses mentioned, especially of the mediodorsal thalamus.  

AADC-IR perikarya were also found in the other hypothalamic areas where few or no TH-IR cells have been reported: the supramamillary nucleus, tuberomamillary nucleus, pre- and anterior mamillary nuclei, caudal arcuate nucleus, dorsal hypothalamic area immediately ventral to the mamillothalamic tract, anterior hypothalamic area, area of the tuber cinereum, retrochiasmatic area, preoptic area, suprachiasmatic and dorsal chiasmatic nuclei.  

The mamillothalamic tract appeared intact in both patients. Considering that medial thalamic lesions commonly cause amnesia in human beings as well as nonhuman primates, there are two possible reasons, alone or in combination, that may explain why these patients failed to have amnesia: the amount of DM damage was less than required to cause amnesia; or the amnesia related to thalamic lesions requires damage to a second structure, such as the mamillothalamic tract or the anterior nucleus..  

We suggest that the patient's problem in language and verbal memory reflected a defect in memory processing for verbal material during registration, retention, and retrieval, and that this defect probably resulted from a left anterior thalamic lesion affecting the ventrolateral nucleus, centromedian-parafascicular nuclei complex, internal medullary lamina, or mamillothalamic tract..  

The mamillothalamic tract and the ventral portion of the lamina medullaris interna are the most likely candidates in the mediation of memory processes and a combined lesion of these structures may be responsible for thalamic amnesia in man. Two patients without significant memory dysfunction had lesions in the ventrobasal portion of the mediodorsal nucleus sparing the mamillothalamic tract and the ventral part of the lamina medullaris interna.  

The medial mamillary nucleus was found to project through the mamillothalamic tract to the ipsilateral anteroventral, anteromedial, and interanteromedial nuclei, and by way of the mamillotegmental tract principally to the deep tegmental nucleus (of Gudden). The lateral mamillary nucleus projects through the mamillothalamic tract bilaterally upon the anterodorsal nuclei of the thalamus, and through the mamillotegmental system to the dorsal tegmental nucleus; it also appears to contribute fibers to the medial forebrain bundle.  

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