Utilizing the current procedure reproducible accurate lesions were made in the ansa lenticularis and internal pallidum as confirmed on postoperative MR scans. 
Although several studies, including our own tracer investigations, suggest that motor projections from GPi principally form the lenticular fasciculus and non-motor projections primarily contribute to the ansa lenticularis, other schemes have perpetuated.
In the tegmentum, DARPP-32 was observed in axons descending from the telencephalon via the ansa lenticularis.
These axons often follow a long and tortuous course within the GPi and then emerge either through the ansa lenticularis (AL) or the lenticular fasciculus (LF), irrespective of the location of their parent cell body in the GPi.
A field of cholinergic neurons in the rostral avian hindbrain was named the nucleus pedunculopontinus tegmenti, whereas the anterior nucleus of the ansa lenticularis in the avian diencephalon was renamed the subthalamic nucleus, both for their evident mammalian homologues.
After BDA injections into nucleus rotundus, retrogradely labelled neurons were observed consistently within the following neuronal groups in the midbrain and the diencephalon: (i) the stratum griseum centrale of the optic tectum; (ii) the nucleus subpretectalis in the pretectum; (iii) the nucleus ansa lenticularis posterior, the posterior nucleus of the ventral supraoptic commissure, and the posteroventral nucleus, in the dorsal thalamus and (iv) the lateral suprachiasmatic nucleus and part of the reticular complex in the ventral thalamus.
These thin and varicose collaterals emerge from thick and smooth axons that course along the main output pathways of the basal ganglia, including the ansa lenticularis, the lenticular fasciculus and Wilson's pencils.
In the mesencephalon, intensely stained, multipolar neurons were abundantly scattered in the central gray, nucleus intercollicularis, reticular formation, nucleus tegmenti pedunculo-pontinus, pars compacta, area ventralis of Tsai, and ansa lenticularis.
The extra-amygdaloid outputs of the amygdalostriatal transition area are sparse and include moderate projections to the caudoventral globus pallidus, the ansa lenticularis, and the substantia nigra pars lateralis.
In opposition to generally accepted schemes, the findings from this study suggest that the pallidothalamic fibers originating from the caudal portions of GPi, including the motor territory, do not course ventromedially to form the ansa lenticularis, but rather, travel predominately medially through the lenticular fasciculus en route to the thalamus.
We report here evidence indicating that the so-called anterior nucleus of the ansa lenticularis (ALa) is the avian homolog of mammalian STN.
In the diencephalon, CGRPi perikarya were present mainly in the shell of the thalamic nucleus ovoidalis, the nucleus semilunaris paraovoidalis, the nucleus dorsolateralis posterior thalami, and in the hypothalamic nucleus of the ansa lenticularis.
A variable pattern in the region of the base of the globus pallidus was observed, with 10 of 19 cases demonstrating a decrease and 8 cases an increase, consistent with the proximity of a CSF cistern in the former and the ansa lenticularis and optic tract in the latter.
These thin and varicose collaterals emerge from thick and smooth axons that course backward along the main output pathways of the basal ganglia, including the ansa lenticularis, the lenticular fasciculus and Wilson's pencils.
OBJECTIVE: Because interruption of pallidal outflow signals by pallidotomy is believed to play an important role in the motor improvement in Parkinson's disease, the anatomical relationship of the two major pallidofugal tracts, namely the ansa lenticularis (AL) and the fasciculus lenticularis (FL) to the Leksell pallidotomy target (LPT) were studied.
Originally, the globus pallidus and the ansa lenticularis were the surgical targets but were replaced at the end of the 1950s by the ventrolateral thalamus.
A possible anatomical basis for these differential functional effects could be a functional somatotopy within the GPi, with the segregation of the pallidofugal fibers from the outer portion of the GPi, on one hand, forming the ventral ansa lenticularis and from the inner portion of the GPi, on the other hand, forming the dorsal lenticular fasciculus..
A large number of surgical procedures involving the globus pallidus and ansa lenticularis were performed from 1939 to the late 1950s for alleviation of rigidity and tremor, two of the main symptoms of Parkinson's disease.
Labeled fibers and terminals were also observed in the avian subthalamic nucleus (anterior nucleus of the ansa lenticularis), in the pretectum (nucleus spiriformis lateralis) and in the avian substantia nigra pars reticulata.
P50 and N80 were limited to the ventralmost of the GPi and the ansa lenticularis. Left half field stimulation evoked responses in the right ansa lenticularis region while right half field stimulation did not, and vice versa. The location of the recording electrode in the ansa lenticularis region did not modify the scalp VEP.
Until the introduction of L-dopa in the therapeutics of idiopathic Parkinson's disease (IPD) at the end of the 60's, treatment was essentially limited to anticholinergic drugs and surgical procedures devised to produce discrete lesions in the pallidum, ansa lenticularis and thalamus.
In our technique the probe is guided to the optimum target at the most ventral pallidum and ansa lenticularis by macroelectrode stimulation of the internal capsule and optic tract from within the globus pallidus, with the thresholds providing a relative measure of the electrode proximity to these structures. Microelectrode recording to electrophysiological neuronal activity at various points along the trajectory towards the target showed distinct firing patterns providing identification of the globus pallidus externus and internus, ansa lenticularis, and optic tract. Macroelectrode electrophysiological stimulation within the target volume, inducing threshold responses in the internal capsule and optic tract, provides for accurate localization of the most effective PVP target in the ansa lenticularis.
Labeled fibers from the caudal GP distribute to the caudate-putamen, nucleus of the ansa lenticularis, reuniens, reticular thalamic nucleus (mainly its posterior extent), and along a thin strip of the zona incerta adjacent to the cerebral peduncle.
OBJECTIVE: The purpose of this study is to define the morphology of the boundary between the globus pallidus and the ansa lenticularis (i.e., pallidal base) in humans. CONCLUSION: We conclude that the pallidal base is not a smooth, sharp boundary between the globus pallidus and the ansa lenticularis. One model depicts the pallidal base as a multifolded boundary that distinctly separates pallidal neurons from ansa lenticularis axons. Another model depicts the pallidal base as an indistinct transitional boundary between the globus pallidus and the ansa lenticularis, which contains axonal fibers intermixed with small clusters of pallidal neurons.
Extensive lesions in medial diencephalic and bordering areas of telencephalon, ansa lenticularis, lateral and medial forebrain bundle diminished approach tendencies and greatly attenuated the genetically influenced red preferences.
The paleostriatal complex is the source of the ansa lenticularis with projections to the nucleus spiriformis lateralis and the nucleus tegmenti pedunculopontinus, both projecting to the deep tectum.
Among the brainstem regions receiving GABAergic basal ganglia input, the anterior and posterior nuclei of the ansa lenticularis showed very low levels of all three receptors, while the lateral spiriform nucleus and the ventral tegmental area/substantia nigra complex contained moderate abundance of the three binding sites.
Telencephalic neurons demonstrating the mRNA for choline-O-acetyltransferase and choline-O-acetyltransferase-like immunoreactivity were found in the caudate-putamen nucleus, nucleus accumbens, olfactory tubercule, Islands of Calleja complex, medial septal nucleus, vertical and horizontal limbs of the diagonal band, substantia innominata, nucleus basalis, and nucleus of the ansa lenticularis, as well as occasionally in the amygdala.
Moderate to dense degeneration was also seen in several forebrain and midbrain areas including the paleostriatum, ansa lenticularis, the dorso-intermediate thalamic nucleus, lateral spiriform, pedunculopontine tegmental, and lateral mesencephalic nuclei and in the deeper layers of the optic tectum.
Telencephalic neurons containing the mRNA for the cholinergic synthetic enzyme were found in the caudate-putamen nucleus, nucleus accumbens, olfactory tubercule, islands of Calleja complex, medial septal nucleus, vertical and horizontal limbs of the diagonal band, substantia innominata, nucleus basalis, and nucleus of the ansa lenticularis.
The cells in the peripallidal region (the substantia innominata, nucleus basalis magnocellularis and ansa lenticularis) with choline acetyltransferase immunoreactivity did not contain horseradish peroxidase.
More caudally, a dense bundle of positive fibers was observed at the level of the ansa lenticularis, the inferior thalamic peduncle, and the adjoining bed nucleus of the stria terminalis.
The labeled fibers reached these ipsilateral thalamic nuclei by coursing along or through the ansa lenticularis, the lenticular and thalamic fasciculi, and the Forel's fields.
Although regional nuances were apparent, a general trend emerged in which cholinergic projection neurons in the basal nuclear complex (i.e., medial septal nucleus, vertical and horizontal diagonal band nuclei, magnocellular preoptic field, substantia innominata, nucleus basalis, and nucleus of the ansa lenticularis) demonstrated ChAT-like immunoreactivity earlier in postnatal development than intrinsically organized cholinergic cells in the caudate-putamen nucleus and nucleus accumbens, although this disparity was less apparent for local circuit neurons in the olfactory tubercle and Islands of Calleja complex.
Furthermore, additional oxytocinergic neurons could be found in the lateral subcommissural nucleus, the zona incerta and the ansa lenticularis of repeatedly mated males.
Oxytocin-immunostained neurons in the perifornical region, the lateral hypothalamus and the ventral ansa lenticularis were mostly absent in males.
ChAT fibers with dorsolateral orientations were additionally observed in the zona incerta, ventral anterior thalamus, and ansa lenticularis on route to the reticular thalamus, the globus pallidus, and the substantia innominata.
Neurons could also be seen in the medial septal nucleus and embedded in myelinated fibre tracts such as those of the external capsule, cingulum, medullary laminae of the globus pallidus, ansa penduncularis, ansa lenticularis, and anterior commissure.
In contrast, the globus pallidus received a dense dopaminergic innervation deriving mostly from two fascicles that coursed backward along the two major output pathways of the pallidum: the lenticular fasciculus caudodorsally and the ansa lenticularis rostroventrally.
GABA+ axons were found throughout the diencephalon and mesencephalon but were especially prominent in the ansa lenticularis, fasciculus medialis longitudinalis, and optic tract.
In the subthalamus, TH neurons completely surround the ventral peduncle of the forebrain bundle (which contains fibers of the ansa lenticularis) and extend into the ventromedial and ventrolateral thalamic areas.
In short term estradiol treated animals, additional immunoreactive perikarya could be observed in the septohypothalamic nucleus, the lateral subcommissural area, the medial preoptic area, the perifornical region, the zona incerta and the ansa lenticularis.
The ansa lenticularis was demyelinated on both sides.
Dopaminergic fibers reached the globus pallidus by coursing along its two major output pathways: the lenticular fasciculus dorsally and the ansa lenticularis ventrally.
A basal forebrain pathway, containing SRIF and NPY immunoreactive fibers, enters the thalamus in association with the ansa lenticularis and SP fibers also ascend from the substantia nigra..
Immunoreactive fibers were also observed in the caudate putamen, amygdala, septum, ventromedial nucleus of the hypothalamus, medial forebrain bundle, ansa lenticularis, and ventromedial portion of the internal capsule and crus cerebri.
Injection of biotin-wheat germ agglutinin into the basolateral nucleus of the amygdaloid complex of the rat labeled many neurons in the substantia innomionata, ventral pallidum, horizontal limb of the diagonal band, interstitial nucleus of the ansa lenticularis, and bed nucleus of the stria terminalis. This highest density of the double-labeled cells was seen in the horizontal limb of the diagonal band and substantia innominata, less numerous in the ventral pallidum and a few double-labeled cells in the interstitial nucleus of the ansa lenticularis..
The results show the efferents derived from these cell groups ascend to the telencephalon via the medial and lateral forebrain bundles, ansa lenticularis, and quintofrontal and occipitomesencephalic tracts.
Efferents from each of these nuclei ascend to the telencephalon via the medial and lateral forebrain bundles, ansa lenticularis, and the quintofrontal and occipitomesencephalic tracts.
Stimulation in the ventrolateral internal segment of the globus pallidus (GPi) or in the ansa lenticularis reduced movement times, whereas stimulation at many sites in the external pallidal segment (GPe), dorsal GPi, and putamen increased movement times for the contralateral arm.
Fibers containing dynorphins and neo-endorphins seem to pass through the internal capsule, ansa lenticularis, and medial forebrain bundle on their way from the striatum to the substantia nigra..
Radiolabeled SP was acid extracted from discrete regions of this striatonigral SP projection--corpus striatum (SP-immunopositive cell bodies), ansa lenticularis (striatonigral SP axons), and substantia nigra (striatonigral SP terminals)--and was purified to a constant specific activity by sequential HPLC.
Basal forebrain neurons projecting to the frontal cortex were found primarily in nucleus basalis, but others were located in association with the substantia innominata/lateral preoptic area, magnocellular preoptic area, and ansa lenticularis.
The noradrenergic, serotoninergic and cholinergic afferents reach the hippocampal formation along three routes: a supracallosal pathway, a subcallosal pathway (along the fimbria-fornix), and a ventral pathway (along the ansa lenticularis and the ventral amygdaloid pathway).
At present, the evidence is that the discharges from the island of Reil are through the extrapyramidal system, a part of the ansa lenticularis system.
Postmortem examination revealed axonal spheroids in the ansa lenticularis and the area surrounded by the substantia innominata, amygdala and supraoptic nucleus.
The SpL was found to receive clear-cut major inputs from only three nuclei: (1) the ipsilateral paleostriatum primitivum (PP) of the basal ganglia (the avian homologue of the mammalian globus pallidus), (2) the ipsilateral anterior nucleus of the ansa lenticularis (ALa) of the diencephalon, and (3) the ipsilateral nucleus tegmentipedunculopontinus (TPc) of the mesencephalon. Two other cell groups may give rise to a slight projection to the ipsilateral SpL: (1) the posterior nucleus of the ansa lenticularis (ALp) of the diencephalon and (2) the nucleus semilunaris (SLu) of the isthmic brainstem. Two other cell groups may give rise to a slight projection to the ipsilateral SpL: (1) the posterior nucleus of the ansa lenticularis (ALp) of the diencephalon and (2) the nucleus semilunaris (SLu) of the isthmic brainstem.
Intensity staining AChE-containing cells projecting to frontal sensorimotor (Area 10), parietal (Area 2), and temporal (Area 4) cortices were found ipsilaterally in nucleus preopticus magnocellularis, in nucleus basalis, and in association with the substantia innominata, the ansa lenticularis, and the lateral hypothalamic area; an essentially rostrocaudal topography was observed for these projections.
The nuclei identified include: the medial mamillary nucleus (in which at least three distinct subdivisions can be recognized--a pars medialis, a pars lateralis, and a pars basalis); the small-celled nucleus intercalatus; the large-celled lateral mamillary nucleus; a single premamillary nucleus; the tuberomamillary nucleus; the posterior hypothalamic nucleus; the caudal extension of the lateral hypothalamic area; the supramamillary area; and the paramamillary nucleus (which appears to correspond to the nucleus of the ansa lenticularis of other workers).
Bilateral destruction of the ansa lenticularis (AL) resulted in a more prolonged period of aphagia (4 days) and an average 8-day period to recover lost body weight.
An apparent long-distance effect of KA was also observed, since intracerebral injections of KA into the PC was followed by cell loss in the ipsilateral nucleus of the ansa lenticularis.
These brain stem injections also labeled a band of cells surrounding the entopeduncular nucleus in the zona incerta, lateral hypothalamus, of the ansa lenticularis and central nucleus of the amygdala.
The bed nucleus of the ansa lenticularis (BNAL) was studied by the rapid Golgi method in the mouse. Dendrites of the BNAL neurons were distributed only within the confines of the ansa lenticularis (AL).
The stimulus positions eliciting the largest hypothalamic effects on the jaw reflexes were located in a region extending medio-laterally from the perifornical area to the entrance of the ansa lenticularis in the lateral hypothalamus.
the paleostriatum primitivum (PP), comparable to globus pallidus, receives projections from the small cells of PA, and from neutrons in the anterior nucleus of the ansa lenticularis (ALa).
Areas of greatest beta-lipotropin content are hypothalamus (with cell bodies in the medial basal hypothalamus and arcuate regions), periventricular nucleus of the thalamus, ansa lenticularis, zona compacta of the substantia nigra, medial amygdaloid nucleus, zona incerta, periaqueductal central gray area, locus ceruleus, and a few fibers in the reticular formation.
Cells in sublenticular portions of SI, and those extending into the medullary laminae of the pallidum, appear to project to: (1) HB1 via the stria medullaris, (2) the pars compacta of SN, (3) lateral and posterior regions of the hypothalamus, and (4) the so-called nucleus of the ansa lenticularis.
Multiple divisions leave this tract towards the epithalamic or the intralaminar thalamic nuclei, the stria terminalis, the septum, the capsula interna and the ansa lenticularis.
The otehr group coursed ventrolaterally in the internal capsule and, without forming an ansa lenticularis, entered the zona incerta, swept medially through and ventral to the medial lemniscus, and terminated in the medial part of the VE and throughout the VD..
It has been demonstrated (Gary Bobo and Bonvallet 1975) that long-lasting stimulation of the "amygdaloid area for the defence reaction" (basal nucleus, pars magnocellularis) elicits, after an initial facilitation, a delayed inhibition of the monosynaptic masseteric reflex (MR), while stimulation of the amygdalofugal fibers running in the ansa lenticularis provokes an immediate inhibition of the reflex.
The main efferent pathway mediating these motor effects is probably the ansa lenticularis..
lentiformis, the ansa lenticularis, the thalamus, the hypothalamus and the gray matter of the spinal cord.
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