The Experts below are selected from a list of 180 Experts worldwide ranked by ideXlab platform
Asla Pitkanen - One of the best experts on this subject based on the ideXlab platform.
-
Projections from the amygdaloid complex to the claustrum and the endopiriform Nucleus: a Phaseolus vulgaris leucoagglutinin study in the rat.
The Journal of comparative neurology, 2002Co-Authors: Katarzyna Majak, Esa Jolkkonen, Samuli Kemppainen, Maria Pikkarainen, Asla PitkanenAbstract:The claustrum and the endopiriform Nucleus contribute to the spread of epileptiform activity from the amygdala to other brain areas. Data of the distribution of pathways underlying the information flow between these regions are, however, incomplete and controversial. To investigate the projections from the amygdala to the claustrum and the endopiriform Nucleus, we injected the anterograde tracer Phaseolus vulgaris leucoagglutinin into various divisions of the amygdaloid complex, including the lateral, Basal, Accessory Basal, central, anterior cortical and posterior cortical nuclei, the periamygdaloid cortex, and the amygdalohippocampal area in the rat. Analysis of immunohistochemically processed sections reveal that the heaviest projections to the claustrum originate in the magnocellular division of the Basal Nucleus. The projection is moderate in density and mainly terminates in the dorsal aspect of the anterior part of the claustrum. Light projections from the parvicellular and intermediate divisions of the Basal Nucleus terminate in the same region, whereas light projections from the Accessory Basal Nucleus and the lateral division of the amygdalohippocampal area innervate the caudal part of the claustrum. The most substantial projections from the amygdala to the endopiriform Nucleus originate in the lateral division of the amygdalohippocampal area. These projections terminate in the central and caudal parts of the endopiriform Nucleus. Lighter projections originate in the anterior and posterior cortical nuclei, the periamygdaloid cortex, the medial division of the amygdalohippocampal area, and the Accessory Basal Nucleus. These data provide an anatomic basis for recent functional studies demonstrating that the claustrum and the endopiriform Nucleus are strategically located to synchronize and spread epileptiform activity from the amygdala to the other brain regions. These topographically organized pathways also provide a route by means of which the claustrum and the endopiriform Nucleus have access to inputs from the amygdaloid networks that process emotionally significant information.
-
Projections from the lateral, Basal, and Accessory Basal nuclei of the amygdala to the entorhinal cortex in the macaque monkey.
Hippocampus, 2002Co-Authors: Asla Pitkanen, Jennifer L. Kelly, David G. AmaralAbstract:We used the anterograde tracers Phaseolus vulgaris-leucoagglutinin (PHA-L) and biotinylated dextran amine (BDA) to examine the projections from the lateral, Basal, and Accessory Basal nuclei of the amygdaloid complex to the entorhinal cortex in Macaca fascicularis monkeys. The heaviest amygdaloid projections originate in the lateral Nucleus, which innervates the rostrally situated entorhinal fields but does not project to the caudal entorhinal cortex. The most extensive projections originate in the ventral division of the lateral Nucleus. Injections in this subdivision lead to moderate to heavy fiber and terminal labeling in the entorhinal cortex, rostral levels of the rostral intermediate EI (ER) and lateral fields, (ELr), and light labeling in the olfactory field EO. The projections from all portions of the lateral Nucleus terminate most heavily in layer III. Layer II of EO and ER also receives a substantial input from the ventral division of the lateral Nucleus. Layer II of ELr receives light innervation from all portions of the lateral Nucleus that project to layer III. Projections from the Basal Nucleus arise mainly from the parvicellular division and are light to moderate in density. Fibers terminate predominantly in ELr, ER, EO, and the caudal portion of the lateral field (Elc); only the most rostral portion of EI receives projections. While fibers from the Basal Nucleus innervate the same layers as the projections from the lateral Nucleus, they tend to have a more vertical or radial orientation within the entorhinal cortex. Electron microscopic analysis of these fibers and terminals indicates that they overwhelmingly form asymmetrical synapses onto dendrites and dendritic spines. The Accessory Basal Nucleus provides a light projection to the same regions of the entorhinal cortex innervated by the lateral and Basal nuclei. Hippocampus 2002;12:186–205. © 2002 Wiley-Liss, Inc.
-
Projections from the Lateral, Basal and Accessory Basal Nuclei of the Amygdala to the Perirhinal and Postrhinal Cortices in Rat
Cerebral cortex (New York N.Y. : 1991), 2001Co-Authors: Maria Pikkarainen, Asla PitkanenAbstract:The projections from the amygdaloid complex to the hippocampus and surrounding cortex have a critical role in the formation of memories for emotionally arousing stimuli and in the spread of epileptic seizures. The present study investigated the organization of amygdaloid projections to the perirhinal and postrhinal cortices by injecting the anterograde tracer Phaseolus vulgaris leucoagglutinin into the different subdivisions of the lateral, Basal or Accessory Basal nuclei of the amygdala in rat (n = 53). Analysis of immunohistochemically stained sections indicated that the medial and dorsolateral divisions of the lateral Nucleus project heavily to layers I-V of caudal area 35 and to layers I-III of the rostroventral postrhinal cortex. The dorsolateral division also moderately innervates layer I of caudoventral area 36. The magnocellular division of the Basal Nucleus projects moderately to layers V and VI of rostral areas 35 and 36. The parvicellular division of the Accessory Basal Nucleus projects moderately to layer V of caudal area 35, whereas the magnocellular division projects moderately to layers I and II of rostral area 35. Via these substantial, topographically organized projections, the amygdaloid complex might modulate information processing at different levels of the medial temporal lobe memory system.
-
Interconnectivity between the amygdaloid complex and the amygdalostriatal transition area: A PHA-L study in rat
The Journal of Comparative Neurology, 2001Co-Authors: Esa Jolkkonen, Samuli Kemppainen, Maria Pikkarainen, Asla PitkanenAbstract:The amygdala orchestrates the formation of behavioral responses to emotionally arousing stimuli. Many of these responses are initiated by the central Nucleus, which converges information from other amygdaloid nuclei. Recently, we observed substantial projections from the amygdala to the amygdalostriatal transition area, which is located dorsal to the central Nucleus. These projections led us to question whether the amygdalostriatal transition area has a role in the initiation of behavioral responses in emotionally arousing circumstances. To explore this anatomically, we traced the interconnections between the amygdalostriatal transition area and the amygdaloid complex using the anterograde tracer Phaseolus vulgaris-leucoagglutinin. The lateral (the medial division and the caudal portion of the dorsolateral division) and the Accessory Basal nuclei (the parvicellular division) provide moderate-to-heavy projections to the amygdalostriatal transition area. Projections back to the amygdala are light and are composed of thin, faintly stained varicose fibers that resemble the labeling of cholinergic terminals. The extra-amygdaloid outputs of the amygdalostriatal transition area are sparse and include moderate projections to the caudoventral globus pallidus, the ansa lenticularis, and the substantia nigra pars lateralis. These data suggest that the amygdalostriatal transition area is one of the major targets for projections originating in the lateral and Accessory Basal nuclei of the amygdala. Via these pathways, emotionally significant stimuli can evoke behavioral responses that are different from those initiated via projections from the amygdala to the central Nucleus. One such candidate response is the orienting response (i.e., saccadic eye movements and head direction) in a pathway that includes a projection from the lateral/Accessory Basal Nucleus of the amygdala to the amygdalostriatal transition area, and from there to the substantia nigra, pars lateralis. J. Comp. Neurol. 431:39–58, 2001. © 2001 Wiley-Liss, Inc.
-
Distribution of parvalbumin, calretinin, and calbindin-D28k immunoreactivity in the rat amygdaloid complex and colocalization with ?-aminobutyric acid
The Journal of comparative neurology, 2000Co-Authors: Samuli Kemppainen, Asla PitkanenAbstract:To understand the organization of inhibitory circuitries in the rat amygdala, the distribution of parvalbumin, calretinin, and calbindin immunoreactivity was investigated in the rat amygdaloid complex. Colocalization of various calcium-binding proteins with the inhibitory transmitter γ-aminobutyric acid (GABA) was studied by using the mirror technique. Parvalbumin-immunoreactive (-ir) elements were located mostly in the deep amygdaloid nuclei, whereas the calretinin-ir and calbindin-ir staining were most intense in the cortical nuclei as well as in the central Nucleus and the amygdalohippocampal area. Second, the distribution of immunopositive neurons largely parallelled the distribution of terminal and neuropil labeling. Third, immunostained neurons could be divided into four major morphologic types (types 1–4) based on the characteristics of the somata and the dendritic trees. The fourth lightly stained neuronal type that had a pyramidal GABA-negative soma was observed only in calretinin and calbindin preparations. Fourth, parvalbumin-ir terminals formed basket-like plexus and cartridges, which suggests that parvalbumin labels GABAergic inhibitory basket cells and axo-axonic chandelier cells, respectively. Colocalization studies indicated that 521 of 553 (94%) of parvalbumin-ir, 419 of 557 (75%) of calbindin-ir, and 158 of 657 (24%) of calretinin-ir neurons were GABA-positive in the deep amygdaloid nuclei. A high density of large GABA-negative calbindin-ir neurons was observed caudally in the medial division of the lateral Nucleus and GABA-negative calretinin-ir neurons were observed in the magnocellular division of the Accessory Basal Nucleus as well as in the intermediate and parvicellular divisions of the Basal Nucleus. These data suggest that in various amygdaloid areas, neuronal excitability is controlled by GABAergic neurons that contain different calcium-binding proteins. The appearance of basket-like plexus and cartridges in the parvalbumin preparations, but not in calretinin preparations, suggests that like in the hippocampus, the distribution of inhibitory terminals in the dendritic and perisomatic regions of postsynaptic neurons in the rat amygdala is organized in a topographic manner. J. Comp. Neurol. 426:441–467, 2000. © 2000 Wiley-Liss, Inc.
David G. Amaral - One of the best experts on this subject based on the ideXlab platform.
-
Delineations of the amygdala subregions examined.
2014Co-Authors: John T. Morgan, David G. Amaral, Nicole Barger, Cynthia M. SchumannAbstract:A. Delineation outlined on a Nissl stained section and B. transferred onto an Iba1- and H & E- stained section and aligned using morphological features, fiber tracts, and cytoarchitectonic boundaries. AB: Accessory Basal Nucleus, B: Basal Nucleus, C: central Nucleus, L: lateral Nucleus, O: "other nuclei", a subregion comprising the remaining amygdaloid nuclei, including the anterior cortical Nucleus, anterior amygdaloid area, Nucleus of the lateral olfactory tract, periamygdaloid cortex, medial Nucleus, posterior cortical Nucleus, amygdalohippocampal area, and intercalated nuclei. Scale bar: 2 mm.
-
Stereological Analysis of Amygdala Neuron Number in Autism
The Journal of neuroscience : the official journal of the Society for Neuroscience, 2006Co-Authors: Cynthia M. Schumann, David G. AmaralAbstract:The amygdala is one of several brain regions suspected to be pathological in autism. Previously, we found that young children with autism have a larger amygdala than typically developing children. Past qualitative observations of the autistic brain suggest increased cell density in some nuclei of the postmortem autistic amygdala. In this first, quantitative stereological study of the autistic brain, we counted and measured neurons in several amygdala subdivisions of 9 autism male brains and 10 age-matched male control brains. Cases with comorbid seizure disorder were excluded from the study. The amygdaloid complex was outlined on coronal sections then partitioned into five reliably defined subdivisions: (1) lateral Nucleus, (2) Basal Nucleus, (3) Accessory Basal Nucleus, (4) central Nucleus, and (5) remaining nuclei. There is no difference in overall volume of the amygdala or in individual subdivisions. There are also no changes in cell size. However, there are significantly fewer neurons in the autistic amygdala overall and in its lateral Nucleus. In conjunction with the findings from previous magnetic resonance imaging studies, the autistic amygdala appears to undergo an abnormal pattern of postnatal development that includes early enlargement and ultimately a reduced number of neurons. It will be important to determine in future studies whether neuron loss in the amygdala is a consistent characteristic of autism and whether cell loss occurs in other brain regions as well.
-
Projections from the lateral, Basal, and Accessory Basal nuclei of the amygdala to the entorhinal cortex in the macaque monkey.
Hippocampus, 2002Co-Authors: Asla Pitkanen, Jennifer L. Kelly, David G. AmaralAbstract:We used the anterograde tracers Phaseolus vulgaris-leucoagglutinin (PHA-L) and biotinylated dextran amine (BDA) to examine the projections from the lateral, Basal, and Accessory Basal nuclei of the amygdaloid complex to the entorhinal cortex in Macaca fascicularis monkeys. The heaviest amygdaloid projections originate in the lateral Nucleus, which innervates the rostrally situated entorhinal fields but does not project to the caudal entorhinal cortex. The most extensive projections originate in the ventral division of the lateral Nucleus. Injections in this subdivision lead to moderate to heavy fiber and terminal labeling in the entorhinal cortex, rostral levels of the rostral intermediate EI (ER) and lateral fields, (ELr), and light labeling in the olfactory field EO. The projections from all portions of the lateral Nucleus terminate most heavily in layer III. Layer II of EO and ER also receives a substantial input from the ventral division of the lateral Nucleus. Layer II of ELr receives light innervation from all portions of the lateral Nucleus that project to layer III. Projections from the Basal Nucleus arise mainly from the parvicellular division and are light to moderate in density. Fibers terminate predominantly in ELr, ER, EO, and the caudal portion of the lateral field (Elc); only the most rostral portion of EI receives projections. While fibers from the Basal Nucleus innervate the same layers as the projections from the lateral Nucleus, they tend to have a more vertical or radial orientation within the entorhinal cortex. Electron microscopic analysis of these fibers and terminals indicates that they overwhelmingly form asymmetrical synapses onto dendrites and dendritic spines. The Accessory Basal Nucleus provides a light projection to the same regions of the entorhinal cortex innervated by the lateral and Basal nuclei. Hippocampus 2002;12:186–205. © 2002 Wiley-Liss, Inc.
-
Organization of the intrinsic connections of the monkey amygdaloid complex: projections originating in the lateral Nucleus.
The Journal of comparative neurology, 1998Co-Authors: Asla Pitkanen, David G. AmaralAbstract:We have used the anterograde tracer, Phaseolus vulgaris-leucoagglutinin (PHA-L) to study the intrinsic projections of the lateral Nucleus of the Macaca fascicularis monkey amygdaloid complex. A reanalysis of the monkey lateral Nucleus indicated that there are at least four distinct cytoarchitectonic divisions: dorsal, dorsal intermediate, ventral intermediate, and ventral. The major projections within the lateral Nucleus originate in the dorsal, dorsal intermediate, and ventral intermediate divisions and terminate in the ventral division. The ventral division also projects to itself but does not project significantly to the other divisions of the lateral Nucleus. Thus, the ventral division appears to be a site of convergence for information entering all other portions of the lateral Nucleus. There are substantial regional and topographic differences in the projections from each of the lateral Nucleus divisions to other amygdaloid nuclei. The dorsal division projects to all divisions of the Basal and Accessory Basal nuclei, to the periamygdaloid cortex, the Nucleus of the lateral olfactory tract, the dorsal division of the amygdalohippocampal area, and the lateral capsular nuclei. The dorsal intermediate division projects to the intermediate and parvicellular divisions of the Basal Nucleus, to the parvicellular division of the Accessory Basal Nucleus, and to the periamygdaloid cortex. The ventral intermediate division projects to the magnocellular division of the Accessory Basal Nucleus and to the parvicellular division of the Basal Nucleus. The major projections from the ventral division are directed to the parvicellular division of the Basal Nucleus, the parvicellular division of the Accessory Basal Nucleus, the medial Nucleus, and the periamygdaloid cortex. Projections from all portions of the lateral Nucleus to the central Nucleus are generally very light. It appears, therefore, that each division of the lateral Nucleus originates topographically organized projections to the other amygdaloid areas that terminate in distinct portions of the target regions. The topographic organization of intrinsic amygdaloid projections raises the possibility that serial and parallel sensory processing may take place within the amygdaloid complex. J. Comp. Neurol. 398:431–458, 1998. © 1998 Wiley-Liss, Inc.
-
Organization of connections between the amygdaloid complex and the perirhinal and parahippocampal cortices in macaque monkeys
The Journal of comparative neurology, 1996Co-Authors: Lisa Stefanacci, Wendy A. Suzuki, David G. AmaralAbstract:Neuroanatomical studies in macaque monkeys have demonstrated that the perirhinal and parahippocampal (PRPH) cortices are strongly interconnected with the hippocampal formation. Recent behavioral evidence indicates that these cortical regions are importantly involved in normal recognition memory function. The PRPH cortices are also interconnected with the amygdaloid complex, although comparatively little is known about the precise topography of these connections. We investigated the topographic organization of reciprocal connections between the amygdala and the PRPH cortices by placing anterograde and retrograde tracers throughout these three regions. We found that there was an organized arrangement of connections between the amygdala and the PRPH cortices and that the deep (lateral, Basal, and Accessory Basal) nuclei of the amygdaloid complex were the source of most connections between the amygdala and the PRPH cortices. The temporal polar regions of the perirhinal cortex had the strongest and most widespread interconnections with the amygdala. Connections from more caudal levels of the perirhinal cortex had a more discrete pattern of termination. Perirhinal inputs to the amygdala terminated primarily in the lateral Nucleus, the magnocellular and parvicellular divisions of the Basal Nucleus, and the magnocellular division of the Accessory Basal Nucleus. Return projections originated predominately in the lateral Nucleus, the intermediate and parvicellular divisions of the Basal Nucleus, and the magnocellular division of the Accessory Basal Nucleus. The interconnections between the amygdala and the parahippocampal cortex were substantially less robust than those with the perirhinal cortex and mainly involved the Basal Nucleus. Area TF was more strongly interconnected with the amygdala than was area TH. Input from the parahippocampal cortex terminated predominantly in the lateral half of the parvicellular division of the Basal Nucleus but also to a lesser extent in the magnocellular division of the Basal Nucleus and the lateral Nucleus. Return projections originated predominantly in the magnocellular division of the Basal Nucleus and were directed almost exclusively to area TF. ‘i) 1996 Wiley-Liss, Inc. Indexing terms: amygdala, medial temporal lobe, memory, emotion, topography, cortical connections
Julie L. Fudge - One of the best experts on this subject based on the ideXlab platform.
-
Translating Fear Circuitry: Amygdala Projections to Subgenual and Perigenual Anterior Cingulate in the Macaque.
Cerebral cortex (New York N.Y. : 1991), 2019Co-Authors: K K Sharma, Emily A. Kelly, C W Pfeifer, Julie L. FudgeAbstract:Rodent fear-learning models posit that amygdala-infralimbic connections facilitate extinction while amygdala-prelimbic prefrontal connections mediate fear expression. Analogous amygdala-prefrontal circuitry between rodents and primates is not established. Using paired small volumes of neural tracers injected into the perigenual anterior cingulate cortex (pgACC; areas 24b and 32; a potential homologue to rodent prelimbic cortex) and subgenual anterior cingulate cortex (sgACC, areas 25 and 14c; a potential homologue to rodent infralimbic cortex) in a single hemisphere, we mapped amygdala projections to the pgACC and sgACC within single subjects. All injections resulted in dense retrograde labeling specifically within the intermediate division of the Basal Nucleus (Bi) and the magnocellular division of the Accessory Basal Nucleus (ABmc). Areal analysis revealed a bias for connectivity with the sgACC, with the ABmc showing a greater bias than the Bi. Double fluorescence analysis revealed that sgACC and pgACC projections were intermingled within the Bi and ABmc, where a proportion were double labeled. We conclude that amygdala inputs to the ACC largely originate from the Bi and ABmc, preferentially connect to the sgACC, and that a subset collaterally project to both sgACC and pgACC. These findings advance our understanding of fear extinction and fear expression circuitry across species.
-
Amygdala projections to central amygdaloid Nucleus subdivisions and transition zones in the primate.
Neuroscience, 2009Co-Authors: Julie L. Fudge, Tracy TuckerAbstract:In rats and primates, the central Nucleus of the amygdala (CeN) is most known for its role in responses to fear stimuli. Recent evidence also shows that the CeN is required for directing attention and behaviors when the salience of competing stimuli is in flux. To examine how information flows through this key output region of the primate amygdala, we first placed small injections of retrograde tracers into the subdivisions of the central Nucleus in Old world primates, and examined inputs from specific amygdaloid nuclei. The amygdalostriatal area and interstitial Nucleus of the posterior limb of the anterior commissure (IPAC) were distinguished from the CeN using histochemical markers, and projections to these regions were also described. As expected, the Basal Nucleus and Accessory Basal Nucleus are the main afferent connections of the central Nucleus and transition zones. The medial subdivision of the central Nucleus (CeM) receives a significantly stronger input from all regions compared to the lateral core subdivision (CeLcn). The corticoamygdaloid transition zone (a zone of confluence of the medial parvicellular Basal Nucleus, paralaminar Nucleus, and the sulcal periamygdaloid cortex) provides the main input to the CeLcn. The IPAC and amygdalostriatal area can be divided in medial and lateral subregions, and receive input from the Basal and Accessory Basal Nucleus, with differential inputs according to subdivision. The piriform cortex and lateral Nucleus, two important sensory interfaces, send projections to the transition zones. In sum, the CeM receives broad inputs from the entire amygdala, whereas the CeLcn receives more restricted inputs from the relatively undifferentiated corticoamygdaloid transition region. Like the CeN, the transition zones receive most of their input from the Basal Nucleus and Accessory Basal Nucleus, however, inputs from the piriform cortex and lateral Nucleus, and a lack of input from the parvicellular Accessory Basal Nucleus, are distinguishing afferent features.
-
Amygdaloid Inputs Define a Caudal Component of the Ventral Striatum in Primates
The Journal of Comparative Neurology, 2004Co-Authors: Julie L. Fudge, Michael A. Breitbart, Crystal R. McclainAbstract:The ventral striatum mediates goal-directed behavior through limbic afferents. One well-established afferent to the ventral striatum is the amygdaloid complex, which projects throughout the shell and core of the Nucleus accumbens, the rostral ventromedial caudate Nucleus, and rostral ventromedial putamen. However, striatal regions caudal to the anterior commissure also receive inputs from the amygdala. These caudal areas contain histochemical and cytoarchitectural features that resemble the shell and core, based on our recent studies. Specifically, there is a calcium binding protein (CaBP)-poor region in the lateral amygdalostriatal area that resembles the “shell.” To examine the idea that the caudal ventral striatum is part of the “classic” ventral striatum, we placed small injections of retrograde tracers throughout the caudal ventral striatum/amygdalostriatal area and charted the distribution of specific amygdaloid inputs. Amygdaloid inputs to the CaBP-poor zone in the lateral amygdalostriatal area arise from the Basal Nucleus, the magnocellular subdivision of the Accessory Basal Nucleus, the periamygdaloid cortex, and the medial subdivision of the central Nucleus, resembling that of the shell of the ventral striatum found in our previous studies. There are also amygdaloid inputs to CaBP-positive areas outside the shell, which originate mainly in the Basal Nucleus. Taken together, the “limbic-related” striatum forms a continuum from the rostral ventral striatum through the caudal ventral striatum/lateral amygdalostriatal area based on histochemical and cellular similarities, as well as inputs from the amygdala.
-
Bcl-2 immunoreactive neurons are differentially distributed in subregions of the amygdala and hippocampus of the adult macaque.
Neuroscience, 2004Co-Authors: Julie L. FudgeAbstract:The amygdala and hippocampus are key limbic structures of the temporal lobe, and are implicated in the pathology of mood disorders. Bcl-2, an intracellular protein, has recently been identified in the primate amygdala and hippocampus, and is now recognized as an intracellular target of mood stabilizing drugs. However, there are few data on the cellular phenotypes of bcl-2-expressing cells, or their distribution in specific subregions of the amygdala and hippocampus. We used a number of histochemical markers to define specific subregions of the primate amygdala and hippocampus, and examined phenotype-specific distributions of bcl-2 immunore-active cells within each subregion. Immature-appearing bcl-2 labeled neurons, which co-contain class III β-tubulin immuno-reactivity, are found in distinct subregions in each structure. In the amygdala, bcl-2 positive neurons with an immature morphology are densely distributed in the paralaminar Nucleus and intercalated cell islands, the parvicellular Basal Nucleus, and the ventral periamygdaloid cortex and amygdalohippocampal area. In the hippocampus, immature-appearing bcl-2-labeled cells are confined to the polymorph layer (subgranular zone), and base of the granule cell layer in the dentate gyrus. Well-differentiated neurons also express bcl-2. In the amygdala, labeled cells with mature phenotypes are concentrated in the parvicellular Basal Nucleus, the Accessory Basal Nucleus, and the periamygdaloid cortex. The medial Nucleus and central extended amygdala also contain many well-differentiated bcl-2 positive cells. In the hippocampus, the dentate gyrus and Ammon’s horn contain many bcl-2 immunoreactive nonpyramidal cells. These are preferentially distributed in the rostral hippocampus. CA3 and CA2 contain relatively higher concentrations of bcl-2-labeled cells than CA1 and the subiculum. Bcl-2 is thus important in intrinsic circuitry of the hippocampus, and in amygdaloid subregions modulated by the hippocampus. In addition, the extended amygdala, a key amygdaloid output, is richly endowed with bcl-2 positive cells. This distribution suggests a role for bcl-2 in circuits mediating emotional learning and memory which may be targets of mood stabilizing drugs.
Lisa Stefanacci - One of the best experts on this subject based on the ideXlab platform.
-
A postmortem stereological study of the amygdala in Williams syndrome
Brain Structure and Function, 2018Co-Authors: Caroline H. Lew, Cynthia M. Schumann, Lisa Stefanacci, Kimberly M. Groeniger, Ursula Bellugi, Katerina SemendeferiAbstract:Perturbations to the amygdala have been observed in neurological disorders characterized by abnormalities in social behavior, such as autism and schizophrenia. Here, we quantitatively examined the amygdala in the postmortem human brains of male and female individuals diagnosed with Williams Syndrome (WS), a neurodevelopmental disorder caused by a well-defined deletion of ~ 26 genes, and accompanied by a consistent behavioral profile that includes profound hypersociability. Using unbiased stereological sampling, we estimated Nucleus volume, number of neurons, neuron density, and neuron soma area in four major amygdaloid nuclei- the lateral Nucleus, Basal Nucleus, Accessory Basal Nucleus, and central Nucleus- in a sample of five adult and two infant WS brains and seven age-, sex- and hemisphere-matched typically developing control (TD) brains. Boundaries of the four nuclei examined were drawn on Nissl-stained coronal sections as four separate regions of interest for data collection. We found that the lateral Nucleus contains significantly more neurons in WS compared to TD. WS and TD do not demonstrate significant differences in neuron number in the Basal, Accessory Basal, or central nuclei, and there are no significant differences between WS and TD in nuclei volume, neuron density, and neuron soma area in any of the four nuclei. A similarly designed study reported a decrease in lateral Nucleus neuron number in autism, mirroring the opposing extremes of the two disorders in the social domain. These results suggest that the number of neurons in the lateral Nucleus may contribute to pathological disturbances in amygdala function and sociobehavioral phenotype.
-
Organization of connections between the amygdaloid complex and the perirhinal and parahippocampal cortices in macaque monkeys
The Journal of comparative neurology, 1996Co-Authors: Lisa Stefanacci, Wendy A. Suzuki, David G. AmaralAbstract:Neuroanatomical studies in macaque monkeys have demonstrated that the perirhinal and parahippocampal (PRPH) cortices are strongly interconnected with the hippocampal formation. Recent behavioral evidence indicates that these cortical regions are importantly involved in normal recognition memory function. The PRPH cortices are also interconnected with the amygdaloid complex, although comparatively little is known about the precise topography of these connections. We investigated the topographic organization of reciprocal connections between the amygdala and the PRPH cortices by placing anterograde and retrograde tracers throughout these three regions. We found that there was an organized arrangement of connections between the amygdala and the PRPH cortices and that the deep (lateral, Basal, and Accessory Basal) nuclei of the amygdaloid complex were the source of most connections between the amygdala and the PRPH cortices. The temporal polar regions of the perirhinal cortex had the strongest and most widespread interconnections with the amygdala. Connections from more caudal levels of the perirhinal cortex had a more discrete pattern of termination. Perirhinal inputs to the amygdala terminated primarily in the lateral Nucleus, the magnocellular and parvicellular divisions of the Basal Nucleus, and the magnocellular division of the Accessory Basal Nucleus. Return projections originated predominately in the lateral Nucleus, the intermediate and parvicellular divisions of the Basal Nucleus, and the magnocellular division of the Accessory Basal Nucleus. The interconnections between the amygdala and the parahippocampal cortex were substantially less robust than those with the perirhinal cortex and mainly involved the Basal Nucleus. Area TF was more strongly interconnected with the amygdala than was area TH. Input from the parahippocampal cortex terminated predominantly in the lateral half of the parvicellular division of the Basal Nucleus but also to a lesser extent in the magnocellular division of the Basal Nucleus and the lateral Nucleus. Return projections originated predominantly in the magnocellular division of the Basal Nucleus and were directed almost exclusively to area TF. ‘i) 1996 Wiley-Liss, Inc. Indexing terms: amygdala, medial temporal lobe, memory, emotion, topography, cortical connections
-
Intrinsic connections of the rat amygdaloid complex: Projections originating in the Accessory Basal Nucleus
The Journal of comparative neurology, 1995Co-Authors: Asla Pitkanen, Lisa Stefanacci, Claudia R. Farb, Joseph E. Ledoux, David G. AmaralAbstract:The amygdaloid complex is involved in associational processes, such as the formation of emotional memories about sensory stimuli. However, the anatomical connections through which the different amygdaloid nuclei process incoming information and communicate with the other amygdaloid nuclei, is poorly understood. As part of an ongoing project aimed at elucidating the intrinsic connections of the rat amygdaloid complex, we injected the anterograde tracer PHA-L (Phaseolus vulgaris-leucoagglutinin) into different rostrocaudal levels of the Basal Nucleus of the amygdala in 21 rats and analyzed the distribution of labeled fibers and terminals throughout the amygdaloid complex. The connectional analysis, together with cytoarchitectonic observations, suggested that contrary to previous notions the Basal Nucleus in the rat has three divisions: magnocellular, intermediate, and parvicellular. The magnocellular division has heavy reciprocal connections with the lateral portion of the parvicellular division and the intermediate division projects weakly to the parvicellular division, whereas the projection from the medial portion of the parvicellular division to the intermediate division is heavy and the lateral and medial portions of the parvicellular division are only weakly interconnected, as are the magnocellular and intermediate divisions. The main intraamygdaloid targets of the Basal Nucleus projections are the Nucleus of the lateral olfactory tract, the anterior amygdaloid area, the medial and capsular divisions of the central Nucleus, the anterior cortical Nucleus, and the amygdalohippocampal area. Our findings provide the most detailed understanding of the intra-amygdala connections of the Basal Nucleus to date and show that the connections within the Basal Nucleus and between the Basal Nucleus and other amygdaloid areas are more widespread and topographically organized than previously recognized.
-
Intrinsic connections of the rat amygdaloid complex: Projections originating in the lateral Nucleus: INTRINSIC CONNECTIONS OF THE RAT AMYGDALA
The Journal of comparative neurology, 1995Co-Authors: Asla Pitkanen, Lisa Stefanacci, Claudia R. Farb, Joseph E. Ledoux, David G. AmaralAbstract:The amygdaloid complex receives sensory information from a variety of sources. A widely held view is that the amygdaloid complex utilizes this information to orchestrate appropriate species-specific behaviors to ongoing experiences. Relatively little is known, however, about the circuitry through which information is processed within the amygdaloid complex. The lateral Nucleus is the major recipient of extrinsic sensory information and is the origin of many intra-amygdaloid projections. In this study, we reinvestigated the organization of intra-amygdaloid projections originating from the lateral Nucleus using the anterograde tracer Phaseolus vulgaris leucoagglutinin (PHA-L). The lateral Nucleus has highly organized intranuclear connections. Dense projections interconnect rostral and caudal levels of the lateral and the medial divisions of the Nucleus, and the lateral and medial divisions of the lateral Nucleus are also interconnected. The major extranuclear projections of the lateral Nucleus are (in descending order of magnitude) to the Accessory Basal Nucleus, the Basal Nucleus, the periamygdaloid cortex, the dorsal portion of the central division of the medial Nucleus, the posterior cortical Nucleus, the capsular division of the central Nucleus, and the lateral division of the amygdalohippocampal area. The pattern of extranuclear projections varied depending on the rostrocaudal or mediolateral location of the injection site within the lateral Nucleus. These findings indicate that intra-amygdaloid projections originating in the lateral Nucleus are both more widespread and more topographically organized than was previously appreciated.
Joseph E. Ledoux - One of the best experts on this subject based on the ideXlab platform.
-
Interamygdaloid projections of the Basal and Accessory Basal nuclei of the rat amygdaloid complex
Neuroscience, 1997Co-Authors: Vesa Savander, Joseph E. Ledoux, Asla PitkanenAbstract:Previous studies suggest that the left and right amygdalae are interconnected in rodents. The origin and topography of these connections have, however, remained obscure. In the present study, we investigated the interamygdaloid projections originating in the different divisions of the Basal and Accessory Basal nuclei of the rat amygdala by using the Phaseolus vulgaris leucoagglutinin anterograde tract-tracing technique. The Basal Nucleus gave rise to substantial interamygdaloid projections. However, the density of the projections depended on the location of Phaseolus vulgaris leucoagglutinin injection in the Basal Nucleus. The magnocellular and intermediate divisions projected heavily to the homonymous regions on the contralateral side, as well as to the Nucleus of the lateral olfactory tract. The parvicellular division projected lightly to the homonymous region on the contralateral side, to the contralateral anterior amygdaloid area and to the medial division of the central Nucleus. The contralateral projections originating in the Accessory Basal Nucleus were light compared to those of the Basal Nucleus. These data indicate that interamygdaloid connections in the rat brain are extensive and topographically organized. Via these connections, one amygdala may rapidly activate the contralateral side. This may explain, for example, why the epileptic seizures in one amygdala spread contralaterally and cause the development of independent seizure activity in kindling model of temporal lobe epilepsy.
-
Lateral Nucleus of the rat amygdala is reciprocally connected with Basal and Accessory Basal nuclei: a light and electron microscopic study
Neuroscience, 1997Co-Authors: Vesa Savander, Joseph E. Ledoux, Riitta Miettinen, Asla PitkanenAbstract:Abstract Information flow within the intra-amygdaloid circuitry has been generally believed to be unidirectional rather than reciprocal, in which case sensory inputs entering the amygdala via the lateral Nucleus would not be modulated by inputs from other amygdaloid regions. In the present study we extend our earlier findings which indicated that the lateral Nucleus of the rat amygdala is reciprocally connected with the Basal and Accessory Basal nuclei. The type of synaptic contacts made by these connections is also characterized at the ultrastructural level. An anterograde tracer, Phaseolus vulgaris leucoagglutinin, was injected into the Basal ( n =22) or Accessory Basal nuclei ( n =12) of the rat amygdala. The results demonstrate that the ventrolateral division of the lateral Nucleus receives projections from the Basal Nucleus, while the medial division receives projections from the Accessory Basal Nucleus. Electron microscopic analyses revealed that axons projecting from the Basal Nucleus formed both asymmetric and symmetric contacts within the ventrolateral division of the lateral Nucleus, whereas axons projecting from the Accessory Basal Nucleus to the medial division of the lateral Nucleus formed only asymmetric synapses with their targets. These findings suggest that the lateral Nucleus receives both inhibitory and excitatory intra-amygdaloid projections and indicate that information flow within the amygdala is not unidirectional as previously thought. The results of this study provide evidence that the early phase of sensory processing within the amygdala is already modified by inputs from other amygdaloid nuclei.
-
Intrinsic connections of the rat amygdaloid complex: Projections originating in the Accessory Basal Nucleus
The Journal of comparative neurology, 1995Co-Authors: Asla Pitkanen, Lisa Stefanacci, Claudia R. Farb, Joseph E. Ledoux, David G. AmaralAbstract:The amygdaloid complex is involved in associational processes, such as the formation of emotional memories about sensory stimuli. However, the anatomical connections through which the different amygdaloid nuclei process incoming information and communicate with the other amygdaloid nuclei, is poorly understood. As part of an ongoing project aimed at elucidating the intrinsic connections of the rat amygdaloid complex, we injected the anterograde tracer PHA-L (Phaseolus vulgaris-leucoagglutinin) into different rostrocaudal levels of the Basal Nucleus of the amygdala in 21 rats and analyzed the distribution of labeled fibers and terminals throughout the amygdaloid complex. The connectional analysis, together with cytoarchitectonic observations, suggested that contrary to previous notions the Basal Nucleus in the rat has three divisions: magnocellular, intermediate, and parvicellular. The magnocellular division has heavy reciprocal connections with the lateral portion of the parvicellular division and the intermediate division projects weakly to the parvicellular division, whereas the projection from the medial portion of the parvicellular division to the intermediate division is heavy and the lateral and medial portions of the parvicellular division are only weakly interconnected, as are the magnocellular and intermediate divisions. The main intraamygdaloid targets of the Basal Nucleus projections are the Nucleus of the lateral olfactory tract, the anterior amygdaloid area, the medial and capsular divisions of the central Nucleus, the anterior cortical Nucleus, and the amygdalohippocampal area. Our findings provide the most detailed understanding of the intra-amygdala connections of the Basal Nucleus to date and show that the connections within the Basal Nucleus and between the Basal Nucleus and other amygdaloid areas are more widespread and topographically organized than previously recognized.
-
Intrinsic connections of the rat amygdaloid complex: Projections originating in the lateral Nucleus: INTRINSIC CONNECTIONS OF THE RAT AMYGDALA
The Journal of comparative neurology, 1995Co-Authors: Asla Pitkanen, Lisa Stefanacci, Claudia R. Farb, Joseph E. Ledoux, David G. AmaralAbstract:The amygdaloid complex receives sensory information from a variety of sources. A widely held view is that the amygdaloid complex utilizes this information to orchestrate appropriate species-specific behaviors to ongoing experiences. Relatively little is known, however, about the circuitry through which information is processed within the amygdaloid complex. The lateral Nucleus is the major recipient of extrinsic sensory information and is the origin of many intra-amygdaloid projections. In this study, we reinvestigated the organization of intra-amygdaloid projections originating from the lateral Nucleus using the anterograde tracer Phaseolus vulgaris leucoagglutinin (PHA-L). The lateral Nucleus has highly organized intranuclear connections. Dense projections interconnect rostral and caudal levels of the lateral and the medial divisions of the Nucleus, and the lateral and medial divisions of the lateral Nucleus are also interconnected. The major extranuclear projections of the lateral Nucleus are (in descending order of magnitude) to the Accessory Basal Nucleus, the Basal Nucleus, the periamygdaloid cortex, the dorsal portion of the central division of the medial Nucleus, the posterior cortical Nucleus, the capsular division of the central Nucleus, and the lateral division of the amygdalohippocampal area. The pattern of extranuclear projections varied depending on the rostrocaudal or mediolateral location of the injection site within the lateral Nucleus. These findings indicate that intra-amygdaloid projections originating in the lateral Nucleus are both more widespread and more topographically organized than was previously appreciated.
