Lobus Parolfactorius

Here, we show that training on a passive avoidance task results in the increased concentration of pregnenolone sulphate in the medial striatum, formerly known as Lobus parolfactorius of female but not male chicks.  

In this paper we provide evidence that noradrenaline acts at beta1-ARs in the basal ganglia (Lobus parolfactorius or medial striatum) in short-term memory processing immediately post-training and demonstrate inhibition of memory by selective AR antagonists at particular times in the sequential memory processing sequence after training.  

In the present study the spatial relation between the dopaminergic and dopaminoceptive structures of the avian medial striatum (formerly: Lobus parolfactorius) was observed by confocal laser scanning microscope in the domestic chick (Gallus domesticus).  

2-[ (14)C]-deoxyglucose uptake increased in two brain regions, the intermediate medial hyperstriatum ventrale (IMHV) and Lobus parolfactorius (LPO) following reminder as it did following training, but the increase was bilateral rather than confined to the left hemisphere and was more marked in LPO than IMHV.  

For example, the Lobus parolfactorius and paleostriatum augmentatum were acknowledged to make up the dorsal subdivision of the striatal part of the basal ganglia and were renamed as the medial and lateral striatum. Additionally, the rostroventral part of what was called the Lobus parolfactorius was acknowledged as comparable to the mammalian nucleus accumbens, which, together with the olfactory tubercle, was noted to be part of the ventral striatum in birds.  

The avian Lobus parolfactorius, equivalent to the medial striatum (caudate-putamen) of mammals, has been shown to be of crucial importance in passive avoidance training in day-old domestic chicks, where the aversive stimulus is the bitter tasting substance methylanthranilate. Here we report that the specific D1 antagonist SCH23390, injected into the Lobus parolfactorius of day-old chicks (Gallus domesticus) prior to training, impaired performance on testing 30min post-training at low doses (0.5 and 25nmol).  

Numerous CRF-ir perikarya and fibers were present in the hyperstriatum, hippocampus, neostriatum, Lobus parolfactorius, and archistriatum, as well as in the nucleus taeniae, nucleus accumbens, and bed nucleus of the stria terminalis, which exhibited the strongest immunolabeling in the telencephalon. The presence of dense populations of CRF-ir perikarya in the medial Lobus parolfactorius, nucleus of the stria terminalis, and paleostriatum ventrale, apparently giving rise to CRF-ir projections to the mesencephalic reticular formation, the parabrachial/pericerulear region, and the dorsal vagal complex, suggests that these telencephalic areas may constitute part of the avian "central extended amygdala." These results have important implications for understanding the role of extrahypothalamic CRF systems in emotional responses in birds..  

In the neural song circuit, robust expression was found in area X of the Lobus parolfactorius (LPO) as well as in other song regions previously reported.  

The main targets of septal projections comprised the ipsi- and contralateral septal nuclei, including the nucleus of the diagonal band, basal ganglia, including the ventral paleostriatum, Lobus parolfactorius, nucleus accumbens, and olfactory tubercle, archistriatum, piriform cortex, and anterior neostriatum.  

The BrdU-positive cells were distributed throughout the brain, including the high vocal center (HVC), Lobus parolfactorius and the ventricle zone (VZ) in telencephalon, the granular cell layer (GCL) of cerebellum.  

A major projection of the medial striatum (Lobus parolfactorius, LPO) of birds is the striato-ventrotegmental pathway projecting to the area ventralis tegmentalis.  

The memory enhancing action of noradrenaline injected into the basal ganglia (Lobus parolfactorius-LPO) was reduced in the presence of the alpha(2)-adrenoceptor antagonist yohimbine, but when noradrenaline was injected into the multi-modal association area (intermediate medial hyperstriatum ventrale-IMHV), yohimbine failed to prevent memory enhancement.  

The archistriatum mediates a neural pathway from the medial part of intermediate hyperstriatum ventrale (in the dorsal pallium) to the Lobus parolfactorius (in the medial striatum), thus is possibly involved in memory formation in the domestic chick.  

White Leghorn x black Australorp chicks were administered 0.5 mM N(omega)-Nitro-L-arginine methyl ester bilaterally into the Lobus parolfactorius (LPO), or unilaterally into the IMHV.  

Effects of bilateral chemical lesions of the medial basal ganglia [ Lobus parolfactorius (LPO)] were examined in 7- to 14-d-old domestic chicks.  

A general agreement in the distribution of BZ1 and alpha1 immunoreactivity was observed in structures such as the olfactory bulb, paleostriata, Lobus parolfactorius and dorsal thalamus, although some discrepancies were observed in areas such as the optic tectum or nucleus isthmi pars parvocellularis, with high BZ1 binding and low or no alpha1 immunolabelling..  

Effects of bilateral chemical lesions of the ventro-medial basal ganglia (Lobus parolfactorius, LPO) were examined in 3-9-day-old domestic chicks.  

By 9 days post-BrdU-injection, there was a significantly greater number of BrdU labelled cells in MeA-trained birds within the IMHV, Lobus parolfactorius (LPO) and TO.  

A model is developed that integrates noradrenergic activity in basal ganglia (Lobus parolfactorius (LPO)) and association cortex (intermediate medial hyperstriatum ventrale (IMHV)) leading to the consolidation of memory 30 min after training.  

Area X, the first station in the AFP, and the surrounding Lobus parolfactorius (LPO), are both parts of the avian basal ganglia.  

Females lack Area X and indeed differential alpha(2)-binding was not observed within the female Lobus parolfactorius.  

The basal part of the avian telencephalon can be divided into the paleostriatum augmentatum, paleostriatum primitivum and Lobus parolfactorius (LPO).  

Additional telencephalic areas include the olfactory lobe, the information storage site Lobus parolfactorius (LPO), the memory site hippocampus, the auditory caudomedial neostriatum implicated in the strength of song learning, and the caudolateral neostriatum, which is comparable to the mammalian prefrontal cortex.  

The avian medial striatum (Lobus parolfactorius, LPO) has been considered an anatomically homogeneous region.  

In contrast, the dorsal part of the archistriatum intermedium, the nucleus taeniae, a medial part of the Lobus parolfactorius and the dorsomedial part of the hippocampus displayed an extremely dense serotonergic innervation.  

An "anterior forebrain pathway," arising from HVc, passing through area X of the Lobus parolfactorius, the medial portion of the dorsolateral nucleus of the anterior thalamus and the lateral magnocellular nucleus of the anterior neostriatum, and finally terminating in RA, is essential for song learning and adult plasticity. The fact that the Lobus parolfactorius is thought to form a part of the avian striatum implies several predictions for the connections of area X and for the properties of its neurons.  

In the present study, DA regulation in the associative NCL and the striatal Lobus parolfactorius (LPO) of pigeons was compared to uncover possible differences corresponding to those between mammalian PFC and striatum.  

Priming in the running wheel additionally induced c-fos expression in the Lobus parolfactorius, while priming by acoustic stimulation produced high c-fos expression in the archistriatum.  

Immunoreactivity was exhibited by telencephalic nuclei previously associated with vocal control pathways on the basis of both tract tracing studies and gene mapping: the central nucleus of the anterior archistriatum (AAc), central nucleus of the lateral neostriatum (NLc), magnocellular nucleus the Lobus parolfactorius (LPOm), the oval nucleus of the ventral hyperstiratum (HVo) and the medial division of the oval nucleus of the anterior neostriatum (NAom).  

Radioimmunoassay examination of the intermediate medial hyperstriatum ventrale 5 or 30 min after training or the Lobus parolfactorius 60 or 120 min after training on the passive avoidance task did not show learning-related differences in absolute levels of DHEA or DHEA-S.  

The dorsal and ventral subdivision of the avian pallidum, along with the basal ganglia component of the vocal control circuit, the magnicellular nucleus of the Lobus parolfactorius, stain heavily for iron.  

Properties of local synapses were analyzed in Lobus parolfactorius (LPO; avian homologue of caudate-nucleus) of quail chicks by using slice preparations in vitro.  

Effects of bilateral kainate lesions of telencephalic basal ganglia (Lobus parolfactorius, LPO) were examined in domestic chicks.  

Fibers immunoreactive for TH (TH-ir) were particularly abundant in the Lobus parolfactorius, the paleostriatum primitivum, and the nucleus septalis lateralis. In most males, a high density of TH-ir fibers outlined the telencephalic song control nuclei including the high vocal center, the nucleus robustus archistriatalis, the nucleus interfascialis, the lateral and medial parts of the magnocellular nucleus of the anterior neostriatum, and area X of the Lobus parolfactorius.  

NPY-ir neurons were seen in the Lobus parolfactorius; hyperstriatum, neostriatum, paleostriatum, and archistriatum; hippocampal and parahippocampal areas; dorsolateral corticoid area; piriform cortex; two thalamic areas contiguous to the n.  

We found 300 microM (+)-SKF 10047 to be amnesic when injected into the Lobus parolfactorius 5 h after training (p < .01).  

Previously described projections (Durand et al., 1997) from HVo to the NAom, NLc, and the magnicellular nucleus of the Lobus parolfactorius (LPOm) were confirmed..  

The highest densities of immunoreactive fibers were detected in the Lobus parolfactorius, paleostriatum augmentatum and substantia nigra/area ventralis of Tsai.  

PK 11195 at a concentration of 1-10 microM was found to be amnesic when injected directly into the Lobus parolfactorius (LPO) 5 h after training (P<.01).  

Bilateral injections of cyt-4 directly into the Lobus parolfactorius (LPO) resulted in the chicks being amnesic for the training task 24 hr later, whereas unilateral injections of cyt-4 were effective only when injected into the right LPO.  

In sexually active males exposed to long-day (LD) photoperiod, perikarya in the olfactory bulb, Lobus parolfactorius, n.  

The Lobus parolfactorius (LPO) is thought to be an important site for the second wave of protein synthesis which occurs 4-5 h after training.  

Memory formation for a passive avoidance task in the domestic chick is likely to involve a hyperstriatum ventrale (IMHV)-archistriatum-Lobus parolfactorius (LPO) arc.  

Two hours post-training there was an increase in the number of Fos-positive stained nuclei in right intermediate medial hyperstriatum ventrale (IMHV) (P < 0.01), left IMHV (P < 0.05), right Lobus parolfactorius (LPO) (P < 0.025) and left LPO (P < 0.05) of birds trained on the bitter bead compared with controls that had pecked a water-coated bead.  

Here, we show that the HA also is the origin of a set of intratelencephalic projections with terminal fields in the lateral part of the frontal neostriatum, the shell surrounding the lateral magnocellular nucleus of the anterior neostriatum, the Lobus parolfactorius surrounding area X, the nucleus interface, auditory fields L1 and L3, the shelf underlying the high vocal center, the dorsolateral caudal neostriatum, the dorsocaudal part of the nucleus robustus archistriatalis, and the ventral archistriatum.  

A significant increase occurred bilaterally in the quantity of bound alpha-BgT in the Lobus parolfactorius, while the amount of bound QNB decreased significantly, and bilaterally, in the hippocampus, hyperstriatum ventrale, Lobus parolfactorius and posterolateral telencephalon, pars dorsalis.  

The stimulation of adenylyl cyclase (AC) by dopamine was investigated in membrane fractions of the forebrain areas mediorostral neostriatum/hyperstriatum ventrale (MNH) and Lobus parolfactorius (LPO) of 8-day-old domestic chicks that had been raised under different social conditions: group A, socially isolated; group B, imprinted on an acoustic stimulus; group C, trained but nonimprinted; and group D, reared in small groups.  

The nuclei investigated were the hypoglossal nucleus, dorsomedial nucleus of the intercollicular midbrain, central nucleus of the archistriatum, central nucleus of the lateral neostriatum, oval nucleus of the hyperstriatum ventrale, medial division of the oval nucleus of the anterior neostriatum, and magnocellular nucleus of the Lobus parolfactorius.  

caeruleus, quantitative receptor autoradiography was used to localize NMDA (N-methyl-D-aspartate)-sensitive [ 3H]glutamate, [ 3H]MK801, and [ 3H]AMPA binding sites, in six regions of the forebrain: hippocampus and parahippocampus, hyperstriatum accessorium (vision) and ventrale (sensory integration), neostriatum (auditory), and Lobus parolfactorius (basal ganglia).  

The basal phosphorylation of CaMKII from the intermediate medial hyperstriatum ventrale (IMHV) and Lobus parolfactorius (LPO) regions of the chick brain is shown to be largely right hemisphere-lateralized.  

Numerous fibres of this system persist until adulthood, mainly in the Lobus parolfactorius, lamina medullaris dorsalis and lamina frontalis superior.  

Among the similarities are the existence of recursive pathways interconnecting vocal control neurons in the archistriatum, basal ganglia (i.e., Lobus parolfactorius), and dorsal thalamus. Despite these similarities, the budgerigar dorsal striatopallidum (Lobus parolfactorius, paleostriatum augmentatum, and paleostriatum primitivum) and somatomotor (anterior) archistriatum exhibit unique patterns of ELI.  

In particular, DARPP-32 was highly abundant in the avian basal ganglia, where a high percentage of neurons were labelled in the "striatal" parts (paleostriatum augmentatum, Lobus parolfactorius), while only neuropil staining was observed in the "pallidal" portions (paleostriatum primitivum).  

An area of the chick striatum, the Lobus parolfactorius plays an important role in one-trial passive avoidance learning tasks. However, on the basis of studies of synaptic morphometry, a region of striatum, the Lobus parolfactorius (LPO), appears to play a more important role in longer term memory storage for the task..  

Very low ir-ACTH and -beta E contents were found in the archistriatum and in the Lobus parolfactorius.  

The results of this study suggest that the chick archistriatum can be divided into two basic divisions according to whether they project to the following limbic structures: the hippocampal formation, septal areas, Lobus parolfactorius, nucleus accumbens, ventral paleostriatum, and dorsomedial thalamus.  

(3) The ventral intermediate archistriatum is another region that is also a source of intratelencephalic projections, in particular of those to the Lobus parolfactorius.  

Both, DARPP-32 positive neurons as well as D1 receptors were highly enriched in the striatal part of the basal ganglia including the Lobus parolfactorius (LPO) and paleostriatum augmentatum.  

A distinct cell type was NOS-labeled in the Lobus parolfactorius (LPO) in the telencephalon, and neurons were labeled in the area ventralis of Tsai (AVT), the substantia nigra (nucleus tegmenti pedunculo-pontinus, pars compacta, TPc), and the locus coeruleus in the brainstem.  

The Lobus parolfactorius (LPO) has been implicated in memory formation associated with passive avoidance training of young posthatch domestic chicks.  

This study examined effects on memory formation produced by [ Leu]enkephalin and [ Met]enkephalin administration in 2 regions of the 2-day-old chick brain involved in memory formation: the intermediate medial hyperstriatum ventrale (IMHV) and the Lobus parolfactorius (LPO).  

Previously reported projections from HVo and NAo upon the magnocellular nucleus of the Lobus parolfactorius (LPOm), and after LPOm onto the magnocellular nucleus of the dorsal thalamus (DMm; G.F.  

The mediorostral neostriatum/hyperstriatum ventrale (MNH) and neostriatum dorsocaudale (Ndc) of the domestic chick are crucially involved in auditory filial imprinting, whereas the Lobus parolfactorius (LPO) seems to be involved in the emotional modulation of behavior.  

In males, the Nissl-defined volume of the high vocal center, the robust nucleus of the archistriatum, and area X of the Lobus parolfactorius increased with age, reaching the adult value at 60, 50, and at 40 days posthatching, respectively.  

The magnicellular nucleus of the Lobus parolfactorius in budgerigars, like the area X in songbirds, contained many ChAT labeled somata, fibers, and varicosities and stained densely for AChE.  

In the present study, we used immunohistochemical labeling with antibodies against tyrosine hydroxylase (TH) or dopamine (DA) to study the dopaminergic input to the striatal portion of the basal ganglia in pigeons (i.e., Lobus parolfactorius and paleostriatum augmentatum).  

Between days 0 and 2 the D2-receptor density increased significantly in the Lobus parolfactorius and paleostriatum augmentatum while for D1-receptor density no significant changes were detectable.  

Dorsolateral injections gave rise to projections innervating the rostralmost extension of the HP, a laminar complex including the dorsal and ventral hyperstriata and the lamina frontalis superior, the rostral Lobus parolfactorius, the medial and ventral paleostriatal regions, the lateral septal nucleus, the nucleus of the diagonal band, the dorsolateral corticoid area, the archistriatum posterius, and the nucleus taeniae in the telencephalon.  

In a further series of experiments, where we exposed animals from both experimental groups to handling distress, glutamate levels in MNH showed only a slight increase, whereas we observed a pronounced increase of extracellular glutamate in the Lobus parolfactorius (LPO), the avian analogue of the basal ganglia.  

The efferent projections of each of the three major parts of NB were mainly to the adjacent neostriatum frontale (NF), which then provided projections to the Lobus parolfactorius (exclusive of area X), the lateral archistriatum intermedium (Ail), and the lateral neostriatum caudale (NCl).  

High levels of specific binding of the D1 and D2 ligands were found in the striatal regions (paleostriatum augmentatum and Lobus parolfactorius) of the one-day-old chick, as reported previously in the pigeon, turtle and rat, whilst binding levels were considerably lower in the pallidum (paleostriatum primitivum), hippocampus and hyperstriatum ventrale. These experiments demonstrated a large and highly significant bilateral increase (compared to control birds) in binding to D1 (but not D2) receptors in the Lobus parolfactorius.  

The amnesic effects of protein kinase inhibitors (H-7, HA-156, TFP, W-9, and W-13) on memory formation for a one trial peck-avoidance task in chicks were investigated with bilateral and unilateral injections into either the left or the right intermediate medial hyperstriatum ventrale (IMHV) or the left or right Lobus parolfactorius (LPO).  

While validating some of the known projections to be preserved in the in vitro slice preparation, we were also able to identify a new projection from neurones of the lateral portion of the magnocellular nucleus of the anterior neostriatum towards area X of the Lobus parolfactorius..  

Weakly labeled cells were found in the rostral neostriatum, Lobus parolfactorius, and mesencephalic reticular formation.  

High densities of binding sites were detected in the Lobus parolfactorius, olfactory tubercle, and paleostriatum augmentatum.  

DA- and TH-like fibers reached their highest density in the paleostriatum augmentatum and the Lobus parolfactorius of the basal ganglia.  

Long-term increases in synaptic density (first recorded 24 h after training of chicks on a one-trial passive avoidance task, and still present 48 h post training), are found bilaterally in a part of the striatum, the Lobus parolfactorius (LPO) [ 23,36], and are believed to reflect a trace of long-term memory formation.  

It has been shown that the anterior forebrain pathway sequentially connects the following nuclei: the high vocal center, area X of Lobus parolfactorius, the medial portion of the dorsolateral thalamic nucleus, the lateral magnocellular nucleus of anterior neostriatum (IMAN), and the robust nucleus of the archistriatum (RA).  

Two regions in the forebrain of domestic chicks (Gallus domesticus), the intermediate and medial hyperstriatum ventrale and the Lobus parolfactorius, have previously been shown to be important centres of biochemical, pharmacological and physiological change following one-trial passive avoidance training. The purpose of the present study was to examine, at the electron microscopic level, the fine spatial re-arrangement of synaptic structures in the intermediate and medial hyperstriatum ventrale (at 30 min), and in the Lobus parolfactorius (at 24 h), post-training using comprehensive biometrical designs, image analysis and stochastic approaches. In the Lobus parolfactorius at 24 h post-training the main changes in synaptic fine structure involved a shift of synaptic vesicles away from synaptic apposition zones in the right hemisphere with the distance between synaptic apposition zones decreasing; in the left Lobus parolfactorius, synaptic apposition zones became more regular/round in shape with a greater distance between them after training.  

However, there was PKC alpha beta-staining of some fibres in the IMHV (but little elsewhere in the hyperstriatum ventrale), in the neostriatum, paleostriatal complex and the Lobus parolfactorius.  

Birds have well-developed basal ganglia within the telencephalon, including a striatum consisting of the medially located Lobus parolfactorius (LPO) and the laterally located paleostriatum augmentatum (PA).  

Increases (805 in the left Lobus parolfactorius and 67% in the left intermediate medial hyperstriatum ventrale) in NMDA sensitive [ 3H]L-glutamate binding occurred in electro-shocked chicks which showed recall of the aversive experience but were absent in MeA-trained chicks rendered amnesic by electro-shock.  

One-trial passive avoidance training in day-old chicks results in a biochemical cascade occurring in two forebrain regions, the intermediate medial hyperstriatum ventrale and the Lobus parolfactorius.  

Following training, a sequence of biochemical, electro-physiological, pharmacological and morphological events takes place within two loci in the forebrain, the intermediate and medial hyperstriatum ventrale (IMHV), and part of the paleostriatal complex, the Lobus parolfactorius (LPO).  

Strongly stained neurones were concentrated in the paleostriatum augmentatum, Lobus parolfactorius, ventral pallidum, olfactory tubercle, parts of the neostriatum, mesencephalic reticular formation and locus coeruleus.  

No significant effects of training were found in the anterior hyperstriatum ventrale, Lobus parolfactorius, neostriatum, medial hippocampal region, or ventrolateral hippocampal region, but counts in this last region were positively correlated with training approach.  

Specific labeling densities were associated with avian equivalents of the mammalian pyramidal system (hyperstriatum accessorium; archistriatum intermedium and tractus occipitomesencephalicus) and extrapyramidal system (paleostriatum augmentatum, paleostriatum primitivum and Lobus parolfactorius), as well as several limbic structures (hippocampal formation, nucleus taeniae and the caudal part of the archistriatum).  

In both the chicken and the pigeon telencephalon, the highest concentration of PPE mRNA-containing cells was observed in the Lobus parolfactorius, paleostriatum augmentatum, nucleus accumbens, and septum.  

In 1-week-old domestic chicks, the connectivity of the Lobus parolfactorius (LPO), part of the avian basal ganglia, was investigated using Phaseolus vulgaris leucoagglutinin and horseradish peroxidase for anterograde and retrograde pathway tracing, respectively.  

The chick archistriatum receives afferents from the intermediate part of the medial hyperstriatum ventrale (IMHV) and projects to the Lobus parolfactorius (LPO).  

(4) CB-HRP traces revealed that HVc projected to robust nucleus of the archistriatum, and atea X of Lobus parolfactorius.  

VIP-ir fibers were seen in the Lobus parolfactorius and throughout the brainstem mainly arranged in lateral and midsagittal position.  

In particular, the avian striatum (Lobus parolfactorius, LPO) received a large number of its neurons during the first 20 days of life, but continued to incorporate new neurons throughout juvenile and adult life.  

The brains of chicks displaying the correct behavioural response (> 90%) were removed and the Lobus parolfactorius from each hemisphere was dissected from the brain and impregnated using a rapid Golgi technique. Significantly higher spine densities were also found on 4th and 5th order branches of neurones in the right Lobus parolfactorius of MeA-trained chicks compared to water-trained chicks. These results suggest that substantial plasticity occurs in post-synaptic structures in the Lobus parolfactorius following passive avoidance training.  

The dorsal zone of Nf projects to the sensorimotor part of archistriatum, to the paleostriatum augmentatum (PA) and to the lateral Lobus parolfactorius.  

Distinct and dense puncta with GABA-LIR were present in DLM, and may be projections from Area X/Lobus parolfactorius (LPO).  

It could also be involved in the organization of avoidance behaviour associated with the task, or it could form part of a circuit linking two other forebrain regions previously implicated in one-trial PAL, the intermediate part of the medial hyperstriatum ventrale and the Lobus parolfactorius..  

The Lobus parolfactorius of the chick forebrain is an important structure for memory of this avoidance response. To examine training-induced electrophysiological changes in this structure, spontaneous neuronal bursting activity was measured from the Lobus parolfactorius of anaesthetized, day-old methyl- and water-chicks (the latter chicks trained to peck at a water-coated bead) over the period 1-10 h post-test. These chicks were anaesthetized and bursting was recorded from the Lobus parolfactorius. These results suggest that passive avoidance training induces a memory-specific, time-dependent increase in neuronal activity within the Lobus parolfactorius of day-old chicks.  

Brain areas containing the most abundant immunoreactive fibers, listed from the rostral-most location, were found in the ventromedial region of the Lobus parolfactorius and the lateral septal n.  

This increase occurs in two forebrain areas: the intermediate medial hyperstriatum ventrale and the Lobus parolfactorius.  

We investigated the volume of hyperstriatum ventrale, pars caudale, nucleus robustus archistriatalis, and area X of the Lobus parolfactorius as defined with the use of a Nissl stain.  

Intensely stained neurons and fibers were found in most parts of the telencephalon, in particular in the neostriatum, paleostriatum augmentatum, olfactory tubercle, Lobus parolfactorius, hyperstriatum accessorium, and hyperstriatum ventrale.  

We also observed an intensely stained area ventral to the fasciculus prosencephali lateralis and lateral to the tractus septomesencephalicus, a weakly to moderately stained band ventral to the Lobus parolfactorius, an intensely stained zone along the lateral ventricle in the hyperstriatum ventrale, and an unstained almond-shaped nucleus in the lateral hyperstriatum ventrale.  

ir-cGnRH II fibers were prominent in limbic structures (cortex piriformis, lateral to nucleus taeniae, hippocampus); olfactory areas (tuberculum olfactorium, nucleus subhabenularis lateralis, nucleus septalis lateralis); areas that in other avian species have steroid-concentrating cells or receptors (medial edge of Lobus parolfactorius, nucleus septalis medialis, nucleus periventricularis magnocellularis, nucleus dorsomedialis posterior thalami); and areas containing ir-GnRH I cells or fibers but not in median eminence.  

However, significant increases were observed in delta binding in the paleostriatum augmentatum of the right hemisphere (16%) and the Lobus parolfactorius of both hemispheres (left, 20%; right, 21%).  

Within the ventral forebrain, most studies have concentrated on the medial basal hypothalamus (also known as the infundibular tuberal complex), however a second locus, the Lobus parolfactorius, has also been identified. Specifically, a group of cerebrospinal fluid (CSF)-contacting neurons in the medial portion of the lateral septal organ (LSO) within the Lobus parolfactorius is a second viable candidate.  

We have performed Scatchard displacement binding analyses to examine changes in both the number and affinity of glutamate receptors in the left and right hyperstriatum ventrale (HV) and also the left and right archistriatal/Lobus parolfactorius (AS/LPO) areas from imprinted and non-imprinted chicks.  

The ventral fiber bundle is conical and traverses the Lobus parolfactorius, crossing also the lamina medullaris dorsalis (the latter consisting mainly of star-shaped cells).  

Passive avoidance training has been shown to cause an increase in synaptic density (Nvsyn) in the Lobus parolfactorius (LPO) of the one-day old chick.  

Of the regions examined, elevations in the titre of YL1/2 were found in the left intermediate hyperstriatum ventrale 1 h, 6 h and 24 h following training, in the left Lobus parolfactorius 1 h following training and in the right Lobus parolfactorius 6 h and 24 h following training.  

Training chicks on a one-trial passive avoidance task results in memory-dependent synaptic remodeling in the intermediate medial hyperstriatum ventrale (IMHV) and Lobus parolfactorius (LPO).  

Tissue samples from intermediate medial hyperstriatum ventrale (IMHV) and Lobus parolfactorius (LPO) were isolated at 6 and 24 h after training.  

Two discrete areas of the chick brain, the intermediate medial hyperstriatum ventrale (IMHV) and Lobus parolfactorius (LPO), were found to have different functions during the formation of memory for a 1-trial peck-avoidance paradigm.  

For NMDA-sensitive [ 3H]glutamate receptors, significant elevations in binding were observed in two regions, the left intermediate and medial hyperstriatum ventrale (IMHV) (39%) and the Lobus parolfactorius (LPO) (34%), at 30 min post-training, but a decrease (44%) occurred in binding to the lateral neostriatum.  

Many of these effects have been localized to two forebrain regions: the left intermediate medial hyperstriatum ventrale and the Lobus parolfactorius. Pretraining lesions in the left intermediate medial hyperstriatum ventrale, or post-training lesions in the Lobus parolfactorius result in amnesia.  

Three forebrain areas in the young chick-the intermediate medial hyperstriatum ventrale (IMHV), the Lobus parolfactorius (LPO), and the paleostriatum augmentatum--have been identified as important structures in mediating learning and memory processes.  

Six major groups of perikarya were found to include the olfactory bulb, olfactory tubercle/Lobus parolfactorius, nucleus accumbens, septal preoptic hypothalamic region (three sub-nuclei), lateral anterior thalamic nucleus and in and about the oculomotor complex.  

Training chicks on a one-trial passive avoidance task was followed by 2- to 2.5-fold increases in c-fos mRNA in both left and right IMHV and Lobus parolfactorius (LPO) 30 min after the learning experience.  

Very low to background levels of VIP binding were detected in the ectostriatum, paleostriatum primitivum, paleostriatum augmentatum, Lobus parolfactorius, nucleus accumbens, most of the brainstem, and the cerebellum. The paleostriatum, Lobus parolfactorius, and ectostriatum were virtually devoid of both binding sites and immunoreactive profiles.  

There was a significant increase in [ 3H]fucose incorporation into the left lateral cerebral area and numerically similar, but non-significant, increases in the intermediate part of the medial hyperstriatum ventrale and Lobus parolfactorius.  

In the vocal motor system the most prominent accumulation of ChAT-IR somata was found in Lobus parolfactorius (LPO) including Area X.  

In the telencephalon, identifiable groups of progestin-accumulating cells were found in the hyperstriatum dorsale, at the medial edge of the Lobus parolfactorius, and in the medial septum.  

Three distinct nuclei of the chick forebrain--the intermediate medial hyperstriatum ventrale (IMHV), Lobus parolfactorius (LPO), and paleostriatum augmentatum (PA)--show metabolic, morphological, and neurophysiological changes following training on a passive avoidance task, suggesting that these and other areas of the chick forebrain participate in memory formation for this task.  

The highest staining intensity was found in the nonprimary sensory regions of the telencephalon such as the hyperstriatum dorsale, hyperstriatum ventrale, hippocampus, palaeostriatum augmentatum, Lobus parolfactorius and caudal parts of neostriatum.  

In zebra finches the song control nuclei hyperstriatum ventralis pars caudalis (HVc) and area X of the Lobus parolfactorius (LPO), continue to add new neurons during the juvenile period of song learning.  

The Lobus parolfactorius (LPO) of the chick has been shown to undergo an increase in the mean synaptic numerical density (Nvsyn) in response to one-trial passive avoidance learning (Stewart et al.  

The higher vocal center (HVc) of the canary brain projects to two forebrain nuclei: robustus archistriatalis (RA) and area X of Lobus parolfactorius.  

Lobus parolfactorius and nucleus vestibularis medialis were labelled by only MAb 270, whereas only MAb 35 labelled nucleus laminaris and the medial and lateral pontine nuclei.  

The long processes of these radial glia showed a mediolateral orientation, and were much more abundant in some parts of the telencephalon (e.g., hyperstriatum, caudal neostriatum, and Lobus parolfactorius) than in others (e.g., anterior neostriatum, archistriatum, and septum), which had few or no radial glia fibers.  

In the telencephalon the highest concentration of specific binding was found in the hyperstriatum ventrale followed by the neostriatum, and then the Lobus parolfactorius of the paleostriatal complex, whilst in the diencephalon highest levels of labelling were present in the infundibulum.  

The highest densities of muscarinic cholinergic receptors in the pigeon brain were localized in the paleostriatum augmentatum and the Lobus parolfactorius, areas homologous to the mammalian corpus striatum.  

A few reactive perikarya were also observed in the nucleus accumbens (Ac) and Lobus parolfactorius (LPO).  

A study of was carried out of Golgi impregnated material in two regions of the paleostriatal complex of the chick telencephalon, the Lobus parolfactorius and paleostriatum augmentatum. Based upon the nature of the axon (bifurcating or nonbifurcating, ascending or descending) and of the dendrites (spiny or aspinous, and thickness), the following subclasses (types) were identified: two projection and three local circuit neurons in the Lobus parolfactorius and two projection and two local circuit neurons in the paleostriatum augmentatum. In addition to known differences in developmental chronology and extrinsic connectivity, the Lobus parolfactorius clearly differs from palaeostriatum augmentatum in cellular composition and organization. From its cytoarchitectonic appearance we would suggest that the Lobus parolfactorius is the paleostriatal region of greater complexity..  

The distribution of gamma-aminobutyric acid (GABA)-ergic elements in 3 forebrain regions (medial mid-telencephalic hyperstriatum ventrale; paleostriatum augmentatum; Lobus parolfactorius) of two-day-old domestic chicks was investigated using (1) light and electron microscope autoradiography following [ 3H]GABA uptake in vitro in combination with pre-embedding GABA immunocytochemistry and (2) Golgi impregnation and 'gold-toning' combined with postembedding GABA immunocytochemistry.  

A morphometric study was made of synapses in both left and right hemispheres of two regions of the chick paleostriatal complex, the paleostriatum augmentatum (PA) and the Lobus parolfactorius (LPO), 24 h after passive avoidance training (methyl anthranilate, M-chicks), and in water-trained controls (W-chicks).  

The enzymatic activities are not evenly distributed in the brain: they are high in the tuberal hypothalamus and Lobus parolfactorius but low in the preoptic area and anterior hypothalamus.  

Measurements were made on three forebrain regions known to show metabolic and morphological change consequent on training--the Lobus parolfactorius (LPO), paleostriatum augmentatum (PA), and medial hyperstriatum ventrale (MHV)--in the right and left hemispheres 2 and 24 h after training chicks on a passive avoidance task, in which they learn to avoid pecking a bead coated with methylanthranilate [ methylanthranilate-trained (M-trained)].  

The dorsal layer sends fibers to the lateral neostriatum, to the rostral "sensorimotor" part of the archistriatum and to the lateral zone of the Lobus parolfactorius.  

Injections centred on different mediolateral regions of the dorsal thalamus produced terminal labelling in correspondingly different mediolateral regions of the striatal complex, comprising paleostriatum augmentation and Lobus parolfactorius, within the ventral paleostriatum, and within the neostriatum.  

The other group of nuclei including HVc, nucleus X of the Lobus parolfactorius (Area X), nucleus dorsointermedius posterior thalami (DIP) and nucleus magnocellularis of anterior neostriatum (MAN) is a modulator of the driving system.  

Lower levels of binding sites were observed within the striatal complex including the laterally situated paleostriatum augmentatum and medially situated Lobus parolfactorius.  

AVT projections reach primarily rostromedial portions of PA as well as the Lobus parolfactorius.  

Within the telencephalon, the following neural structures receive input from neurons in the LoC and subcoeruleus cell groups: the paleostriatal complex including the paleostriatum augmentatum and Lobus parolfactorius, septal nuclei, nucleus accumbens, olfactory tubercle, hippocampus and parahippocampal area, nucleus taeniae, dorsal archistriatum, lateral neostriatum, hyperstriatum dorsale, hyperstriatum ventrale, and preoptic area.  

Thirty or 60 days later, neurons in a forebrain nucleus, hyperstriatium ventralis, pars caudalis (HVc), were labeled by retrograde transport of HRP injected into the only two nuclei known to receive a projection from HVc: robustus archistriatalis (RA) and area X of Lobus parolfactorius.  

(3) The fibers remaining in the MFB ascend into the "ventral paleostriatum," olfactory tubercle, and into the lateral and ventral borders of the rostral portion of Lobus parolfactorius (LPO).  

2-[ 14C] Deoxyglucose injected 1 min prior to training shows increased uptake into the hyperstriatum ventrale (HV) and Lobus parolfactorius (LPO) 30 min later compared with control birds which have pecked a water-coated bead (W).  

This region is clearly separable from paleostriatum augmentatum, Lobus parolfactorius, posterior archistriatum, posteromedial corticoid and septum, all of which also show strong catecholamine fluorescence.  

The CRF neurons were localized in the telencephalon: Lobus parolfactorius, nucleus (n.) accumbens, anterior commissure; in the diencephalon: n.  

The results indicate that descending GABAergic projections are derived from the nucleus accumbens (Ac), ventral Lobus parolfactorius (LPO) and the ventral paleostriatum (VP).  

Numerous small enkephalinergic neurons were observed in both Lobus parolfactorius (LPO) and the paleostriatum augmentatum (PA), the two components of the small-celled portion of the paleostriatal complex.  

Three of the structures, hyperstriatum ventrale (posterior), palaeostriatum augmentatum and Lobus parolfactorius showed significantly enhanced labelling (by 10, 13 and 11%; p less than 0.001, less than 0.05 and less than 0.05 respectively) in the birds which had been trained on the methylanthranilate bead by comparison with those which had pecked at the water-coated bead.  

CRF-containing perikarya were found in the paraventricular, preoptic and mammillary nuclei of the hypothalamus and in some extrahypothalamic areas (nuclei dorsomedialis and dorsolateralis thalami, nucleus accumbens septi, Lobus parolfactorius, periaqueductal gray of the mesencephalon, nucleus oculomotorius ventralis).  

Pigeons with bilateral neurotoxic or electrolytic lesions within ventral mesencephalon, in nucleus tegmenti pedunculo pontinus (TP) (equivalent to substantia nigra) or area ventralis of Tsai (AVT), were found to have catecholamine (CA) depletion in the telencephalon, including the paleostriatum augmentatum (PA) and Lobus parolfactorius (LPO), avian basal ganglia rich in CA.  

HVc projects to area X of Lobus parolfactorius, to RA, and to field Avalanche of hyperstriatum ventrale.  

These regions include the caudal nucleus of the hyperstriatum ventrale (HVc), the robust nucleus of the archistriatum (RA), the magnocellular nucleus of the neostriatum (MAN), area X of the Lobus parolfactorius, nucleus interface (NIF), intercollicular nucleus (ICo), and the tracheosyringeal portion of the hypoglossal motor nucleus (nXIIts).  

In the zebra finch (Poephila guttata), horseradish peroxidase injected into or near Area X of the Lobus parolfactorius (LPO) is transported to cell bodies in ipsilateral hyperstriatum ventrale pars caudale (HVc), area ventralis of Tsai (AVT), and nucleus tegmenti pedunculo-pontinus, pars compacta (TPc).  

The cortex prepiriformis (olfactory cortex), the hyperstriatum ventrale and the Lobus parolfactorius comprised the uncrossed terminal field. The crossed field included the paleostriatum primitivum and the caudal portion of the Lobus parolfactorius, areas which were reached through the anterior commissure.  

The possible involvement of basal telencephalic structures in visually conditioned heart rate change (established by pairing light and foot-shock) was studied in 156 pigeons by evaluating conditioning performance following lesions of the septum or Lobus parolfactorius. Lesions of the Lobus parolfactorius did not affect the orienting response or overall conditioned response levels, but it did slightly prolong the latency of the conditioned heart rate change. It is concluded that the septum, despite its being cardioactive, is not involved in conditioned heart rate change and that the Lobus parolfactorius participates minimally.  

A fourth, area X of the Lobus parolfactorius, is well developed in males of both species, less well developed in femal canaries, and absent or not recognizable in femal zebra finches.  

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