In a second experiment, females exposed to 30 min of conspecific male song had higher levels of 5-HIAA in the caudomedial Nidopallium of the auditory forebrain than birds not exposed to song. 
Contrastingly, correlates of social behaviour were little in pallium and those of familiarity with exposed individuals were identified in hippocampus, medial meso-/Nidopallium, and ventro-caudal Nidopallium.
MFV, MIVl, MVL, and MC receive thalamic inputs different from those of primary sensory pallial regions and have reciprocal connections with the caudolateral Nidopallium (NCL) or arcopallium. MIVm has a strong reciprocal connection with the intermediate medial Nidopallium. MFD has reciprocal connections with the medial frontal Nidopallium, arcopallium, posterior pallial amygdala, dorsolateral corticoid area, and projects to the medial part of medial striatum and hypothalamus. These results indicate that six subdivisions of the mesopallium have strong connections with corresponding portions of the Nidopallium. In particular, the sensory mesopallial components of MFV, MIVl, MVL and MC form parallel pathways to the one-way sensory streams in the Nidopallium and make either feedback or feed forward circuits to the secondary centers of the Nidopallium.
The corresponding structure in birds is the Nidopallium caudolaterale.
RI aggregates were detected first in the olfactory bulb, around embryonic day 14; within 3 days they appeared in the hyperpallium and Nidopallium, where the most intense labeling was observed in the perihatching period. Fainter RI aggregates persisted up to 3 years in the olfactory bulb and Nidopallium caudale.
We then measured ZENK protein immunoreactivity (Zenk-ir) in caudomedial Nidopallium (NCM) and caudomedial mesopallium (CMM), two regions important for perception of conspecific vocalizations.
Apart from the bilateral bulbar afferents, CPi in turn receives unequivocal input from the ipsilateral CPP, hyperpallium densocellulare, dorsal arcopallium, and from a cluster of cells located within the frontolateral Nidopallium.
There was no effect of any treatment on the total number of neurons in area X, and no change in DCX cell densities was detected in the lateral magnocellular nucleus of the anterior Nidopallium, nor in other parts of the Nidopallium. These effects are generally not observed in the rest of the Nidopallium, implying that steroids only act on the attraction and recruitment of new neurons in HVC without having any major effects on their production at the ventricle wall..
Here we show that both estrogen-producing and -sensitive neurons are highly expressed in the caudomedial Nidopallium (NCM), the zebra finch analog of the mammalian auditory association cortex, but not other auditory forebrain areas.
GABRA5 was highly expressed in the caudomedial Nidopallium (NCM), caudomedial mesopallium, and field L2.
One of HVC's primary afferents, the nucleus interface of the Nidopallium (NIf), provides a significant source of auditory input to HVC.
Essential fatty acids (arachidonic acid and docosahexaenoic acid) showed distinctive distributions across the song nuclei, and the 18-carbon fatty acids stearate and oleate discriminated the different core and shell subregions of the lateral magnocellular nucleus of the anterior Nidopallium.
In particular, the caudal medial Nidopallium (the avian analog of the mammalian auditory-association cortex) has been found to contain the neural substrate of auditory memory, paving the way for analyses of the underlying molecular mechanisms.
We hypothesized that treatment of female zebra finches with a glucocorticoid (corticosterone) would increase calbindin expression in the HP and the caudomedial Nidopallium (NCM), a region important for perceptual (song) memories, relative to "blank" controls.
The avian Nidopallium caudolaterale is a multimodal area in the caudal telencephalon that is apparently not homologous to the mammalian prefrontal cortex but serves comparable functions.
Using in situ hybridization we demonstrate that Cck is highly expressed in several discrete brain regions, most prominently the caudalmost portion of the hippocampal formation, the caudodorsal nidopallial shelf and the caudomedial Nidopallium (NCM), the core or shell regions of dorsal thalamic nuclei, dopaminergic cell groups in the mesencephalon and pons, the principal nucleus of the trigeminal nerve, and the dorsal raphe.
Expression of doublecortin, a microtubule-associated protein, is increased by testosterone in the HVC but not in the adjacent Nidopallium, suggesting that neuron production in the subventricular zone, the birthplace of newborn neurons, is not affected.
Moreover, although birds independently evolved a brain region--the caudolateral Nidopallium (NCL)--involved in performing high-order cognitive functions similar to those performed by the PFC, direct connections between the NCL and hippocampus have not been found in birds, and evidence for the transfer of information from the hippocampus to the NCL or other extra-hippocampal regions is lacking.
Lesions of the lateral magnocellular nucleus of the anterior Nidopallium (LMAN), the output nucleus of a cortical-basal ganglia circuit for song, reduce song variability to that of the stereotyped "performance" state.
In situ hybridization and immunohistochemistry indicated that PV was sexually distributed in most of the studied song nuclei, including in the high vocal center (HVC), the robust nucleus of the arcopallium (RA), Area X, and the lateral magnocellular nucleus of the anterior Nidopallium (lMAN) for three studied age groups, namely, posthatching day (PD) 15, 45, and adult.
The lateral portion of the magnocellular nucleus of the anterior Nidopallium (lMAN) is a song nucleus that is important for song learning and seems to be critical for inducing variability in the song structure that is later pruned via a feedback process to produce adult crystallized song.
Additionally, there are significant differences between left and right brain subdivisions within the two pigeon groups, namely a larger left hyperpallium apicale in both pigeon groups and a larger right Nidopallium, left hippocampus and right optic tectum in pigeons with navigational experience.
Molecular neuronal activation was significantly greater in response to tutor song than to novel song or silence in the medial part of the caudomedial Nidopallium (NCM).
Injections of biotinylated dextran amine (BDA) into Av labeled both afferent terminals and neurons in HVC and the interfacial nucleus of the Nidopallium (NIf), suggesting that there is complex feedforward and feedback communication between these nuclei (HVC<-->Av<-->NIf).
As a consequence, DA delivery in Area X also decreased responses to song playback in the cortical output nucleus of the BG loop, the lateral magnocellular nucleus of the anterior Nidopallium.
To examine the female perception of sequence complexity, we tested female auditory processing with respect to sequential differences in the caudomedial Nidopallium and caudomedial mesopallium. The shuffled songs caused lower ZENK expression in both the caudomedial Nidopallium and caudomedial mesopallium.
Here we show that use-dependent neuronal survival also occurs in the higher order auditory processing region of the songbird caudomedial Nidopallium (NCM).
Other plastic song control areas, such as the medial magnocellular nucleus of anterior Nidopallium and the robust nucleus of arcopallium, were specifically avoided by migrating neurons, while migration toward the olfactory bulb showed high specificity, similar to the mammalian rostral migratory stream.
E(2) levels were high in aromatase-rich regions such as caudal medial Nidopallium and hippocampus. E(2) levels were intermediate in the medial preoptic area, ventromedial nucleus of the hypothalamus, lateral and medial magnocellular nuclei of anterior Nidopallium, nucleus taeniae of the amygdala, and Area X. E(2) levels were largely non-detectable in the cerebellum, HVC, lateral Nidopallium and optic lobes. Importantly, E(2) levels were significantly lower in plasma than in the caudal medial Nidopallium.
The cortical nucleus LMAN (lateral magnocellular nucleus of the anterior Nidopallium) provides the output of a basal ganglia pathway that is necessary for acquisition of learned vocal behavior during development in songbirds. The LMAN(shell) pathway forms a recurrent loop that includes a cortical region, the dorsal region of the caudolateral Nidopallium (dNCL), hitherto unknown to be involved with learned vocal behavior.
We trained starlings to recognize conspecific songs and recorded the extracellular spiking activity of single neurons in the caudomedial Nidopallium (NCM), a secondary auditory forebrain region analogous to mammalian auditory cortex.
Most of this work has focused on the caudomedial Nidopallium (NCM), a forebrain area postulated to be the songbird analogue of the mammalian auditory association cortex.
Previously, we found that new neurons recruited into the Nidopallium caudale in isolated birds were less labeled than those of communally housed birds, suggesting that different types of neurons may survive best under different conditions. Hence, social environment does not appear to affect the type of newly recruited Nidopallium caudale neurons..
The cortical nucleus LMAN (lateral magnocellular nucleus of the anterior Nidopallium) provides the output of a basal ganglia pathway that is necessary for vocal learning in juvenile songbirds.
Brains were collected following playback and assessed for neuronal activity by quantifying expression of the protein of the immediate early gene, ZENK, in two brain regions, the caudomedial Nidopallium (NCM) and the caudomedial mesopallium (CMM).
Here, we sought to map this E2-dependent selectivity in the best-studied area of the auditory forebrain, the caudomedial Nidopallium (NCM).
By injecting a neural tract tracer (DiI) into various song nuclei in brain slices, we found that, as in other songbirds, HVC projects to RA and Area X, while Area X projects to the lateral magnocellular nucleus of the anterior Nidopallium (IMAN) and DLM, DLM to IMAN, and IMAN to RA.
Volumetric analysis showed seasonal telencephalon volume changes and more importantly also a volumetric change in the caudal region of the Nidopallium (NCM), a region analogous to the mammalian secondary auditory cortex.
For example: a periventricular/central domain is Enc1-negative in the ventral pallium or Nidopallium; core and shell nuclei appear in the mesopallium; the redefined caudodorsolateral area shows a characteristic pattern; the limits of the densocellular hyperpallium in the dorsal pallium are illuminated; and the postulated entorhinal cortex area is distinct at the posterior telencephalic pole.
Thus, the visual and auditory systems should be integrated in higher associative area, such as Nidopallium caudo-lateralis (NCL) or in an earlier stage, such as the midbrain in the avian brain..
The central caudal Nidopallium (NCC) is a large subdivision of the Nidopallium in the pigeon brain, but its connectional anatomy is unknown. Outside NCC, many labeled neurons were found in the dorsal intermediate mesopallium and medialmost part of the medial intermediate Nidopallium, with a few in the intermediate (AI) and medial (AM) arcopallium.
Androgen receptors are present in all of the major song nuclei, but it is unknown whether levels of androgen receptor mRNA in the telencephalic song regions HVC, the robust nucleus of the arcopallium, and the lateral magnocellular nucleus of the anterior Nidopallium change as a function of season in white-crowned sparrows. We found that levels of androgen receptor mRNA were higher in HVC and the lateral division of the bed nucleus of the stria terminalis of birds in the breeding condition compared with the nonbreeding condition; however, we observed no seasonal differences in levels of androgen receptor mRNA in either the robust nucleus of the arcopallium or the lateral magnocellular nucleus of the anterior Nidopallium.
There was significantly greater Zenk expression in response to female calls compared to silence in the caudomedial Nidopallium, caudomedial mesopallium, and the hippocampus in females, but not in males.
Lmo3 was expressed in most of the ventrolateral pallium in both species, including, in chicken, the piriform cortex and dorsal ventricular ridge (mesopallium, Nidopallium, and arcopallium) and, in mouse, the piriform cortex, most of the claustral complex, and the pallial amygdala. According to these expression patterns, the chicken ventral pallial amygdala appears to include the caudal dorsolateral pallium, the caudal Nidopallium, and the whole arcopallium, and each one relates to a distinct ventricular sector.
Although the forebrain nucleus interface of the Nidopallium (NIf) appears to be the primary auditory input to HVC, NIf lesions made in adult zebra finches do not trigger song decrystallization.
Bilateral electrolytic lesions damaging the posterior part of the arcopallium/posterior pallial amygdala resulted in an increase in fear behaviour in the 'open-field' test, whereas quail with lesions damaging the anterior part of the arcopallium displayed a decrease in an 'overall fear score', compared to quail with bilateral Nidopallium or sham lesions.
Recording of evoked potentials (EP) from the higher auditory center of birds field L of the Nidopallium was used to study the development of the auditory sensitivity in normally developing vs visually deprived pied flycatcher nestlings aged 6-9 days.
Here we show that estradiol regulates auditory processing of acoustic signals in the vertebrate brain, more specifically in the caudomedial Nidopallium (NCM), the songbird analog of the mammalian auditory association cortex.
The output of a basal ganglia-forebrain circuit, LMAN (the lateral magnocellular nucleus of the anterior Nidopallium), has been implicated in song variability.
Perineuronal nets could be identified very early, already on the first postnatal day throughout various regions and nuclei in chicken fore- and midbrains, most expressively in Nidopallium, hyperpallium, lateral striatum, globus pallidus and mesopallium.
We manipulated the photoexperience of female starlings, photostimulated them, briefly exposed them to either long or short songs, and quantified the expression of the immediate-early gene ZENK (EGR-1) in the caudomedial Nidopallium as a measure of activity in the auditory telencephalon.
Cell body sizes and catecholaminergic and serotonergic innervation patterns were investigated in brain areas expected to be sensitive to differences in environmental stimulation: hippocampal substructures and the Nidopallium caudolaterale (NCL), a functional analogue of the prefrontal cortex.
In the present study, we used reverse transcriptase PCR (RT-PCR) and quantitative real-time PCR (qRT-PCR) to demonstrate that the song control regions lateral magnocellular nucleus of the anterior Nidopallium (LMAN), Area X, MSt (medial striatum), HVC and RA (robust nucleus of the arcopallium) expressed higher levels of mu-OR mRNA compared to delta-OR mRNA. In situ hybridization was used to demonstrate that neither LMAN nor Area X could be delineated from the surrounding brain regions [ anterior Nidopallium (ANP) and MSt, respectively], based on OR mRNA expression. However, HVC and RA neurons expressed marginally higher levels of mu-OR mRNA compared to the posterior Nidopallium, which was confirmed by immunohistochemical localization.
Here, we investigate the signals the AFP sends to song motor areas and their dependence on social context by characterizing singing-related activity of single neurons in the AFP output nucleus LMAN (lateral magnocellular nucleus of the anterior Nidopallium).
Therefore, the aim of the present study was twofold: First, to reveal how single units in the pigeon's Nidopallium caudolaterale (NCL), a functional analogue of the mammalian prefrontal cortex (PFC), encode stimuli that differ in visual features but not in behavioral relevance.
Here we show that the expression of several isoforms of synapsins, a group of phosphoproteins thought to regulate the dynamics of synaptic vesicle storage and release, is induced by auditory stimulation with birdsong in the caudomedial Nidopallium (NCM) of the zebra finch (Taeniopygia guttata) brain.
Our findings show, remarkably, that the gamma4-subunit transcript is highly enriched in the major nuclei of the song system, including the lateral magnocellular nucleus of the anterior Nidopallium (LMAN), the medial magnocellular nucleus of the anterior Nidopallium (MMAN), Area X, the robust nucleus of the arcopallium (RA) and the HVC (used as the proper name), as well as Field L, which innervates the area surrounding HVC.
We measured auditory responses to conspecific and heterospecific songs using ZENK protein expression within the caudomedial Nidopallium (NCM) and the mesopallium caudomedial (CMM).
There were no ZENK differences between groups in inferior colliculus or in caudolateral Nidopallium, avian analog to prefrontal cortex.
We applied the D1 agonist SKF81297 and the D1 antagonist SCH23390 into the Nidopallium caudolaterale (NCL), the avian functional analogue of the PFC, and simultaneously in the medial striatum (MSt), by in vivo microdialysis while the animals performed the task.
The caudomedial Nidopallium (NCM) is a telencephalic auditory area that is selectively activated by conspecific vocalizations in zebra finches and canaries.
When the stimulus was a live pigeon compared to all other stimuli, there were more numerous and more darkly-stained ZENK-positive cells in three "association" regions of the telencephalon: the hyperpallium apicale, the lateral portion of the intermediate Nidopallium, and the medial Nidopallium.
They reached the peak at P15 in the lateral magnocellular nucleus of anterior Nidopallium (LMAN) and the caudal medial Nidopallium (NCM), or at P25 in HVC, Area X and the dorsolateral nucleus of the medial anterior thalamus (DLM).
Using quantitative electron microscopy of chick specimens double-labelled against glutamate and DARPP-32 we observed direct synaptic connections between glutamate immunoreactive axon terminals and DARPP-32 labelled dendrites in the MSt and also in the posterolateral telencephalon (Nidopallium caudolaterale, a prefrontal cortex equivalent region) and the hippocampus.
Moreover, an avian brain nucleus that is analogous to the mammalian secondary auditory cortex (the caudo-medial Nidopallium, or NCM) has recently emerged as a plausible site for sensory representation of birdsong, and appears as a well positioned brain region for categorization of songs.
We focused on caudomedial Nidopallium (NCM), an area analogous to parts of the mammalian auditory cortex with selective responses to birdsong.
We show that in caudal Nidopallium of adult male zebra finches, the rostrocaudal position of newly recruited neurons, their age (1 vs 3 months), and the nature of social change (complex vs simple) after the neurons were born affect their survival.
Strong burst suppression is mediated mainly via tonically firing HVC-projecting Uva neurons, whereas a fast burst drive is mediated indirectly via Uva neurons projecting to the nucleus interface of the Nidopallium.
In adults, norepinephrine strongly reduced input from the lateral magnocellular nucleus of the anterior Nidopallium (LMAN) but only slightly reduced the input from nucleus HVC (proper name), the excitatory input from axon collaterals of other RA neurons, and input from GABAergic interneurons.
We found that subsong production in zebra finches does not require HVC (high vocal center), a key premotor area for singing in adult birds, but does require LMAN (lateral magnocellular nucleus of the Nidopallium), a forebrain nucleus involved in learning but not in adult singing.
With a species-specific probe for budgerigar androgen receptor mRNA, we found that the androgen receptor was expressed in the vocal areas, such as the central nucleus of the lateral Nidopallium, the anterior arcopallium, the oval nucleus of the mesopallium, the oval nucleus of the anterior Nidopallium and the tracheosyringeal hypoglossal nucleus.
The medial magnocellular nucleus of anterior Nidopallium (mMAN) projects to the song control nucleus HVC, which is the point of divergence of the two pathways.
Most auditory areas studied to date are located in the caudomedial forebrain of the songbird and include the thalamo-recipient field L (sub fields L1,L2 and L3),the caudomedial and caudolateral mesopallium (CMM and CLM,respectively) and the caudomedial Nidopallium (NCM).
These neural processes are accompanied by increased expression of a few transcription factors, particularly in the caudomedial Nidopallium (NCM), an auditory forebrain area believed to play a key role in auditory learning and song discrimination.
Specifically, the number of ZENK-expressing cells in the caudomedial mesopallium (CMM) was most affected by whether a song was directed or undirected, whereas the caudomedial Nidopallium (NCM) was most affected by whether a song was familiar or unfamiliar.
The authors examined the activity of single neurons in the avian Nidopallium caudolaterale, an area equivalent to the primate prefrontal cortex.
To simulate variation in quality of the song environment, we exposed adult female starlings to 1 week of either long or short songs and then quantified several monoamines and their metabolites in the caudomedial mesopallium and caudomedial Nidopallium (NCM) using high performance liquid chromatography.
Proliferating cells were detected immunohistochemically on brain sections by incorporation of pre-training doses of 5-bromodeoxyuridine (BrdU) into DNA; numbers of new cells were counted in the intermediate medial mesopallium, the intermediate arcopallium, the medial part of the mesopallium and the Nidopallium, the dorsocaudal Nidopallium, the hippocampus, and the parahippocampal region 24 h and seven days after training. However, at seven days post-training, the number of BrdU-containing cells decreased in the medial Nidopallium and mesopallium, in the dorsocaudal Nidopallium, and the right intermediate medial mesopallium.
Both norepinephrine and dopamine displaced the binding of the radioligand though to a different extent in most of the regions studied (e.g., area X, the lateral part of the magnocellular nucleus of anterior Nidopallium, HVC, arcopallium dorsale, ventral tegmental area and substantia grisea centralis) but not in the robust nucleus of the arcopallium.
Neural response to the stimulus was quantified by the amount of protein of the IEG ZENK (also known as zif-268, egr-1, ngf-Ia and krox-24) in the caudal medial Nidopallium (NCM) and caudomedial mesopallium (CMM). Overall, there was more ZENK induction in CMM and the dorsal parts of the caudal medial Nidopallium (NCMd) than in the ventral parts of the caudal medial Nidopallium (NCMv) and males had more ZENK induction than females.
Inside the telencephalon, mesopallium, Nidopallium (+ entopallium + arcopallium) and septum are smaller as well.
We then tested the role of the AFP (basal ganglia circuit) in this feedback-based recovery by ablating the output nucleus of the AFP [ lateral magnocellular nucleus of the anterior Nidopallium (LMAN)].
These ventral regions included subarea L3, medial-ventral subarea L and potentially the secondary auditory region caudal medial Nidopallium.
A caudal forebrain area of zebra finches that comprises a part of the caudal Nidopallium and a part of the intermediate arcopallium is highly activated during courtship. Being involved in the integration of external input and previously stored information, as well as in adding motivational factors, the caudal Nidopallium and intermediate arcopallium should be integrative areas receiving input from many other regions of the brain. Our results indeed show that the caudal Nidopallium receives input from a variety of telencephalic regions including the secondary visual and auditory areas. The intermediate arcopallium is recipient of input from intermediate and caudal Nidopallium, mesopallium and densocellular hyperpallium. Bilateral innervation by ventral intermediate arcopallium indicates links with sensori-motor pathways, while the projection from the caudal Nidopallium to intermediate arcopallium suggests monosynaptic and disynaptic input to downstream motor pathways. These findings support the idea of an involvement of the caudal Nidopallium and the intermediate arcopallium in the control of courtship behavior..
A significant fMRI response was elicited by conspecific song in the primary auditory thalamo-recipient subfield L2a; in neighboring subareas L2b, L3, and L; and in the rostral part of the higher-order auditory area NCM (caudomedial Nidopallium).
Here we show that the thalamo-pallial ("thalamo-cortical") projection (from the medial part of the dorsolateral thalamic nucleus to the lateral magnocellular nucleus of the anterior Nidopallium--DLM to LMAN) within the anterior forebrain loop is composed of cells positive for the calcium-binding protein calbindin.
Cell proliferation was examined in the intermediate medial mesopallium (IMM), arcopallium intermedium (AI), medial part of Nidopallium and mesopallium (MNM), Nidopallium dorso-caudalis (Ndc), hippocampus (Hp) and area parahippocampalis (APH), as well as in corresponding ventricular zones.
In the songbird, the telencephalic nucleus LMAN (lateral magnocellular nucleus of anterior Nidopallium) is necessary for feedback-dependent song decrystallization, although whether and how electrophysiological properties of LMAN neurons change during decrystallization is unknown.
Although the two song types are similar, the level of neural activity and expression of the immediate early gene egr-1 are higher during undirected than during directed singing in the lateral part of the basal ganglia song nucleus AreaX (LAreaX) and its efferent pallial song nuclei lateral magnocellular nucleus of the anterior Nidopallium (LMAN) and the robust nucleus of the arcopallium (RA).
The caudomedial Nidopallium (NCM) of songbirds is a telencephalic area involved in the auditory processing and memorization of complex vocal communication signals.
Telencephalic auditory areas, including field L subfields L1, L2a and L3, as well as the caudomedial Nidopallium (NCM) and mesopallium (CMM), contained GABAergic cells at particularly high densities. Considerable GABA labeling was also seen in the shelf area of caudodorsal Nidopallium, and the cup area in the arcopallium, as well as in area X, the lateral magnocellular nucleus of the anterior Nidopallium, the robust nucleus of the arcopallium and nidopallial nucleus HVC.
We focused on Nidopallium caudale (NC), a brain region which plays a role in sound processing.
The contribution of the AFP to the onset of song destabilization was tested by ablating the output nucleus of this circuit (LMAN, the lateral magnocellular nucleus of the anterior Nidopallium) prior to bilateral HVC microlesions.
When an adult zebra finch is re-exposed to its tutor's song, there is increased neuronal activation in the caudomedial Nidopallium (NCM), the songbird equivalent of the auditory association cortex.
Within the loop, the striatal and pallial nuclei appear to have opposing roles; the striatal vocal nucleus lateral AreaX is required for high ZENK expression in its downstream nuclei, particularly during undirected singing, while the pallial vocal lateral magnocellular nucleus of the anterior Nidopallium is required for lower expression, particularly during directed singing.
Additionally, we found novel inputs to area X from the Nidopallium and arcopallium, the mesencephalic central gray, and the dorsolateralis anterior (DLL) and posterior (DLP) lateralis in the thalamus.
Densely stained DCX-ir cells were found exclusively in parts of the telencephalon that are known to incorporate new neurons in adulthood, in particular the Nidopallium.
Single-cell recordings in the Nidopallium caudolaterale, the avian prefrontal cortex, revealed that some neurons showed climbing activity between cue onset and response.
Using release-dependent block of postsynaptic NMDA receptors by an open-channel antagonist to assay presynaptic function, we showed that transmitter release at RA synapses from both HVC and the lateral magnocellular nucleus of the anterior Nidopallium systematically decreases during the period of song learning, and in adults is about half that of juveniles.
Here we show that the expression of the gene encoding the middle-weight neurofilament (NF-M), an important component of the neuronal cytoskeleton and a useful tool for studying the cytarchitectonic organization of mammalian cortical areas, is highly enriched in large neurons within pallial song control nuclei (nucleus HVC, robustus nucleus of the arcopallium, and lateral magnocellular nucleus of the Nidopallium) of male zebra finches (Taeniopygia guttata).
Similarly, brain mass and high vocal center (HVC), robust nucleus of the arcopallium (RA), and lateral magnocellular nucleus of the anterior Nidopallium (LMAN) volumes did not covary with nestling condition and growth measurements.
We test the hypothesis that the nucleus interface of the Nidopallium (NIf) has an important role for initiating and shaping these sleep-related activity patterns.
PoAc connects reciprocally with two nuclear groups in the cerebrum: 1) a continuum consisting of the caudoventral Nidopallium, lateral part of the caudoventral Nidopallium (NCVl), subNidopallium beneath NCVl, and piriform cortex and 2) rostral areas of the hemisphere, including the frontolateral and frontomedial Nidopallium and the densocellular part of the hyperpallium.
Two forebrain areas in the hyperpallium apicale and in the lateral Nidopallium of isolated male zebra finches are highly active (2-deoxyglucose technique) on exposure to females for the first time, that is first courtship.
Male zebra finches (Taeniopygia guttata) show differential ZENK expression to conspecific and heterospecific songs by day 30 posthatch in auditory perceptual brain regions such as the caudomedial Nidopallium (NCM) and the caudomedial mesopallium (CMM).
However, the arcopallium and posterior amygdaloid pallium differed from a neighboring telencephalic region (Nidopallium; formerly neostriatum) by containing a substantial proportion of cells singly labeled for L-aspartate (15%, vs. 5.3% in the Nidopallium).
The lateral forebrain of zebra finches that comprises parts of the lateral Nidopallium and parts of the lateral mesopallium is supposed to be involved in the storage and processing of visual information acquired by an early learning process called sexual imprinting. Being involved in such a complicated behavioral task, the lateral Nidopallium should be an integrative area receiving input from many other regions of the brain. Our experiments indeed show that the lateral Nidopallium receives input from a variety of telencephalic regions including the primary and secondary areas of both visual pathways, the globus pallidus, the caudolateral Nidopallium functionally comparable to the prefrontal cortex, the caudomedial Nidopallium involved in song perception and storage of song-related memories, and some parts of the arcopallium. The spatial distribution of afferents suggests a compartmentalization of the lateral Nidopallium into several subdivisions. Based on its connections, the lateral Nidopallium should be considered as an area of higher order processing of visual information coming from the tectofugal and the thalamofugal visual pathways. These findings support the idea of an involvement of the lateral Nidopallium in imprinting and the control of courtship behavior..
Orexin-ir projections extended from the paraventricular nucleus rostrally to the preoptic area, laterally towards the medial striatum, Nidopallium, and dorsally along the lateral ventricle towards the mesopallium.
Then, we examined the distribution of SP and ENK in four control nuclei, two in the motor pathway, i.e., HVC and the robust nucleus of arcopallium (RA), and the other two in the forebrain pathway, i.e., Area X and the lateral magnocellular nucleus of the anterior Nidopallium (LMAN).
The involvement of tenascin-C in this juvenile learning task was tested by injections of monoclonal antibodies directed to distinct domains of the tenascin-C molecule into the avian prefrontal cortex analog, the medio-rostral Nidopallium/mesopallium (formerly termed medio-rostral neostriatum/hyperstriatum ventrale), a forebrain area which has been shown to be critically involved in auditory filial imprinting.
We show that lesions of the lateral magnocellular nucleus of the anterior Nidopallium (LMAN), the output nucleus of the AFP, cause a reduction in the moment-by-moment variability in syllable structure during undirected song to the level present during directed song.
Second, double-labeling with an anterograde tracer and PKC immunofluorescence revealed that PKC immunoreactivity in RA was detected on the synaptic terminals from a high premotor vocal nucleus (HVC), but not from the lateral magnocellular nucleus of the anterior Nidopallium (LMAN).
Early establishment of staining patterns within rostral telencephalic song regions [ area X and lateral magnocellular nucleus of the anterior Nidopallium (lMAN)] suggests a role in auditory learning.
We conducted single-cell recordings in the avian Nidopallium caudolaterale, a structure comparable to the mammalian prefrontal cortex.
RA receives input from nucleus HVC via the premotor pathway, and also from the lateral magnocellular nucleus of the anterior Nidopallium (LMAN), part of a basal ganglia-related circuit essential for vocal learning.
Previous work has shown that exposure of males to their tutor song leads to increased expression of immediate early genes (IEGs) in the caudomedial Nidopallium (NCM) and in the caudomedial mesopallium (CMM).
We found that a dorso-ventral tonotopic gradient from low to high frequency stimuli extends from the rostral field L2 to caudal-most caudo-medial Nidopallium (NCM), similar to the frequency-dependent patterns of ZENK gene expression in canary NCM and to electrophysiological responses in other songbird species.
Although only calls induced gene expression in Field L, the primary telencephalic auditory area, both calls and feeding induced gene expression in the frontal lateral Nidopallium (NFl), a brain area in receipt of input from Field L which projects to areas afferent to vocal control nuclei and which is necessary for new call learning.
Nissl staining was used to measure the volumes of four telencephalic song nuclei: Area X, HVC, the robust nucleus of the arcopallium (RA), and the lateral portion of the magnocellular nucleus of the anterior Nidopallium (LMAN).
The corresponding structure in birds is the Nidopallium caudolaterale.
We perform in vivo measurements of the absorption coefficient and the reduced scattering coefficient of the caudal Nidopallium area of the head of a songbird (the zebra finch)..
Recruitment of new neurons in Nidopallium caudale (NC) was higher than in the hippocampal complex (HC); but in both brain regions it was higher in communally housed birds than in birds housed singly, suggesting that the complexity of the social setting affects new neuron survival.
We show that, in the context of song auditory stimulation, Arc expression is induced in several telencephalic auditory areas, most prominently the caudomedial Nidopallium and mesopallium, whereas in the context of singing, Arc is also induced in song control areas, namely nucleus HVC, used as a proper name, the robust nucleus of the arcopallium and the interface nucleus of the Nidopallium.
Here, we report the presence of aromatase in pre-synaptic boutons in the hippocampus and the high vocal centre brain areas with low and undetectable somal aromatase, respectively, in addition to areas with abundant somal aromatase such as the preoptic area and caudomedial Nidopallium.
The intermediate and medial hyperstriatum ventrale/mesopallium (IMHV/IMM), a forebrain memory storage site, was removed together with a control brain region, the posterior pole of the neostriatum/Nidopallium (PPN).
Two of the song-control nuclei in the forebrain, the HVC (used as the proper name) and the interfacial nucleus of the Nidopallium, both show auditory gating, and they receive input from the uvaeform nucleus (Uva) in the thalamus.
Outside of the song system, major areas of expression were in medial Nidopallium (N), hyperpallium apicale (HA), mesopallium ventrale (MV), taenial amygdala (TnA), cerebellar Purkinje cells, and nucleus isthmo-opticus (IO).
The goal of the present study was to determine either the changes in discharge rate of neurons in the pigeon Nidopallium caudolaterale as well as the synchronicity of these neurons during a discriminatory learning task.
The critical forebrain structure for working memory is the Nidopallium caudolaterale (NCL) in birds and the prefrontal cortex (PFC) in mammals.
Hodological evidence from the current study and other reports argues for the possibility that the area corticoidea dorsolateralis might be hodologically comparable to the cingulate cortex, receiving input from a mediodorsal thalamic-relevant subdivision (lateral subdivision of nucleus dorsomedialis anterior, and medial aspect of nucleus dorsolateralis pars medialis), which also projects on the caudal Nidopallium close to (but not coextensive with) the Nidopallium caudolaterale, another potential analogue of avian prefrontal cortex.
We tested to see if the current social context surrounding the hearing bird can modify a sound-induced immediate early gene (IEG) activation in the specific region of the caudomedial Nidopallium (NCM), a songbird brain analogous to the superficial layers of the mammalian primary auditory cortex.
Lesions of the projection from medial dorsolateral nucleus of the thalamus (DLM) to the cortical nucleus lateral magnocellular nucleus of the anterior Nidopallium (LMAN) greatly disrupt song behavior in juvenile birds during early stages of vocal learning.
Most work on IEG expression in songbirds such as zebra finches has focused on playback of acoustic stimuli and its effect on auditory processing areas such as caudal medial mesopallium (CMM) caudal medial Nidopallium (NCM).
N-methyl-D-aspartate (NMDA) receptors in the mammalian prefrontal cortex (PFC) and in the Nidopallium caudolaterale (NCL) of birds, the avian functional equivalent of the PFC, are involved in learning, which also requires processing of context.
In songbirds, parrots, and hummingbirds, which need to learn their songs, exposure to conspecific song leads to increased expression of the immediate early gene (IEG) ZENK in a number of forebrain regions, including the caudomedial Nidopallium (NCM) and the caudomedial mesopallium (CMM).
In the current study we report neural correlates of executive control in the avian Nidopallium caudolaterale, a region analogous to the mammalian prefrontal cortex. Our findings indicate that neurons in the avian Nidopallium caudolaterale participate in one of the core forms of executive control, the control of what should be remembered and what should be forgotten.
The present study examined expression of these IEGs in the caudomedial Nidopallium (NCM), caudomedial mesopallium (CMM; formerly cHV), and the hippocampus (HP) in both sexes at d45 in response to conspecific, heterospecific, or no songs.
After postnatal exposure to a novel 30-min auditory imprinting stimulus, Arc/arg3.1 mRNA was found to be significantly increased in two higher associative areas, the mesopallium intermediomediale (P = 0.002) and the Nidopallium dorso-caudale (P = 0.031), compared with naïve controls. In addition, increases were seen in the medio-rostral Nidopallium/mesopallium (P = 0.054), which is presumed to be the analog of the mammalian prefrontal cortex, and the hyperpallium intercalatum (P = 0.054), but these did not quite reach significance.
However, experiments using the expression of immediate early genes (IEGs) reveal the activation of brain regions outside the song control system, in particular the caudomedial Nidopallium (NCM) and the caudomedial mesopallium (CMM).
We found that females reared with little or no exposure to song have 31% fewer dendritic spines per unit length of dendrite in caudomedial Nidopallium (NCM), a brain area activated by song perception, compared to control females.
These regions include the hippocampal complex, the medial Nidopallium, and the ventromedial arcopallium. Whereas some telencephalic areas that have not been regarded as limbic were also LAMP-rich (e.g., the hyperpallium intercalatum and densocellulare of the Wulst, the mesopallium, and the intrapeduncular nucleus), most nonlimbic telencephalic areas were LAMP-poor (e.g., field L, the lateral Nidopallium, and somatic basal ganglia).
Here we show that vocal variability in the learning songbird is induced by a basal-ganglia-related circuit, the output of which projects to the motor pathway via the lateral magnocellular nucleus of the Nidopallium (LMAN).
The results showed that injections caudal to A 6.75 (Karten and Hodos [ 1967] Baltimore: Johns Hopkins University Press) gave rise to reciprocal connections with subdivisions of the hippocampal formation, TPO, piriform cortex, posterior pallial amygdala, caudoventral Nidopallium, densocellular part of the hyperpallium, lateral hyperpallium, frontolateral Nidopallium, and lateral intermediate Nidopallium.
However, singing-related activity in the anterior forebrain nuclei lateral magnocellular anterior Nidopallium and Area X markedly depends on the social context.
Consistent with this notion, during the normal sensitive period for vocal learning in zebra finches (Taenopygia guttata), there is a decline in the density of dendritic spines within a region essential for song development, the lateral magnocellular nucleus of the anterior Nidopallium (lMAN).
In the bed nucleus of the stria terminalis, ventromedial nucleus, nucleus taeniae, and the caudomedial Nidopallium, although cells containing either protein were easily detectable, the level of co-expression was minimal.
We identified (1) retrograde labeled neurons in the lateral magnocellular nucleus of the anterior Nidopallium (LMAN) projecting to the medial striatum (MSt), and (2) we identified fibers in the MSt labeled by anterograde transport after tracer injection into LMAN.
In particular, it is unknown whether input from the forebrain nucleus interface of the Nidopallium (NIf), which exhibits both sensory and premotor activity, is necessary for both auditory and premotor processing in its target, HVC.
It has been proposed that the lateral magnocellular nucleus of the anterior Nidopallium (LMAN) mediates song plasticity based on auditory feedback.
We found that limited food availability both reduces singing in a cannabinoid antagonist-reversible manner and increases levels of the endocannabinoid 2-arachidonyl glycerol in various brain regions including the caudal telencephalon, an area that contains auditory telencephalon including the L2 subfield of L (L2) and caudal medial Nidopallium (NCM). Development and use of an anti-zebra finch cannabinoid receptor type 1 (CB1) antibody demonstrates distinct, dense cannabinoid receptor expression within song regions including Area X, lMAN (lateral magnocellular nucleus of anterior Nidopallium), HVC, RA (robust nucleus of arcopallium), and L2.
Converging evidence implicates the auditory forebrain regions caudal medial mesopallium (formerly cmHV) and caudal medial Nidopallium in the perceptual processing of conspecific vocalizations in songbirds. One hallmark of the caudal medial mesopallium and caudal medial Nidopallium, areas analogous to mammalian secondary auditory cortical structures, is their robust expression of the immediate-early-gene zenk in response to conspecific songs. Using European starlings operantly trained to recognize the songs of individual conspecifics, we show that the levels and patterns of zenk protein expression in the caudal medial Nidopallium and caudal medial mesopallium differ when song recognition demands are placed on the system. In the caudal medial Nidopallium, however, expression is significantly elevated above basal levels only during the acquisition of novel song discriminations. The results directly implicate the caudal medial Nidopallium and caudal medial mesopallium in at least a portion of the auditory processes underlying vocal recognition. Moreover, the observed differences between these regions imply the functional localization (or at least the concentration) of different auditory processing mechanisms within the caudal medial Nidopallium and the caudal medial mesopallium..
Here, we compared the experience-dependent modulation of ZENK with that of another IEG, FOS, and report that ZENK and FOS expression in the caudomedial mesopallium and caudomedial Nidopallium show different modulation properties that complement natural variation in song-bout length.
Using pharmacological manipulations in vivo, we show that infusion of alpha-adrenergic antagonists into the NIf (nucleus interfacialis of the Nidopallium), an auditory forebrain area, blocks this state-dependent modulation.
The results showed that field L2, the caudomedial Nidopallium (NCM) and the caudomedial mesopallium (CMM) contain a high number of GABAergic cells.
We found that inactivating the interfacial nucleus of the Nidopallium (NIf) could eliminate all auditory-evoked subthreshold activity in both HVC PN types, consistent with NIf serving as the major auditory afferent of HVC.
These areas, which include field L subfields L1 and L3, as well as the adjacent caudomedial Nidopallium (NCM) and caudomedial mesopallium (CMM), are part of the central auditory pathway and constitute a lobule in the caudomedial aspect of the telencephalon.
Auditory neurons in the secondary auditory areas caudal Nidopallium and caudal mesopallium show specific responses to familiar songs or behaviorally relevant songs.
AChE fibres and cells are intensely labelled in the forebrain nucleus area X, strongly labelled in high vocal centre (HVC) perikarya, and moderately to lightly labelled in the somata and neuropil of vocal control nuclei robust nucleus of arcopallium (RA), medial magnocellular nucleus of the anterior Nidopallium (MMAN) and lateral magnocellular nucleus of the anterior Nidopallium (LMAN).
Neurobehavioral studies and neurocomputational models assume a role for NMDA receptors in prefrontal cortex for maintenance processes, while our previous studies on NMDA receptors in the avian prefrontal cortex-analogue, the Nidopallium caudolaterale (NCL), showed them to be involved in response selection functions.
The caudomedial Nidopallium in songbirds is a specialized forebrain auditory region involved in the processing of species-typical vocalizations. We investigated in male canaries the anatomical relationship between tyrosine hydroxylase and cells immunoreactive for the steroid metabolizing enzyme, aromatase, in the caudomedial Nidopallium using double-label immunocytochemistry. Aromatase containing cells in the caudomedial Nidopallium are therefore a major target of catecholaminergic inputs in canary. Interactions between catecholaminergic systems and aromatase in the caudomedial Nidopallium may provide one mechanism for the regulation of estrogens involved in song perception and memorization..
The sectors of the hyperstriatum composing the Wulst (i.e., the hyperstriatum accessorium intermedium, and dorsale), the hyperstriatum ventrale, the neostriatum, and the archistriatum have been renamed (respectively) the hyperpallium (hypertrophied pallium), the mesopallium (middle pallium), the Nidopallium (nest pallium), and the arcopallium (arched pallium).
Strong signals were observed in the hyperpallium accessorium, Nidopallium and nucleus basorostralis pallii, and moderate signals were found in the hippocampus, cortex piriformis, hyperpallium intercalatum, area temporo-parieto-occipitalis, nucleus striae terminalis lateralis, nucleus olfactorius anterior and organum septi lateralis at ED16. Abundant expressions in the hyperpallium, Nidopallium, considered to be similar to the mammalian cortex, as well as in the hippocampus, indicate participation of these molecules in the processing of sensory information, motor function, learning and memory. BN/GRP-immunoreactive neurons and varicosities were found mainly in the pallium, especially in the hyperpallium accessorium and Nidopallium, and this distribution coincided with that of chBRS-3.5 mRNA.
This selectivity is observed in the high vocal center and the nucleus interface of the Nidopallium, two song nuclei that receive input from the bird's auditory system. Field L and caudal mesopallium project directly or indirectly to the high vocal center and nucleus interface of the Nidopallium and are presumed to provide substantial auditory input to the song system.
We show that the entopallium projects laterally and diffusely to the perientopallium and Nidopallium (formerly the neostriatum) and specifically and densely to a teardrop-shaped nucleus in the ventrolateral mesopallium (formerly known as the hyperstriatum ventrale), here called MVL (abbreviation used as a proper name).
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