Hippocampal Formation

The Hippocampal Formation is a main site of synaptic plasticity induced by voluntary exercise.  

Several physiological, pharmacological and behavioral lines of evidence suggest that the Hippocampal Formation is involved in nociception.  

Three HHV6-positive patients showed signal intensity abnormality in extrahippocampal divisions of the olfactory cortex and cortical and subcortical structures that maintain prominent connections with the Hippocampal Formation. Conclusion: Most patients with HHV6 encephalitis have signal intensity abnormalities in the Hippocampal Formation and amygdala and, contrary to prior reports, some also have involvement of limbic structures outside of the medial temporal lobe.  

Research over the last few decades has firmly established that new neurons are generated in selected areas of the adult mammalian brain, particularly the dentate gyrus of the Hippocampal Formation and the subventricular zone of the lateral ventricles.  

We have carried out a detailed analysis of the intrinsic connectivity of the Macaca fascicularis monkey Hippocampal Formation.  

After 5 weeks of study all the rats were sacrificed and coronal sections were taken from the dorsal Hippocampal Formation of the right cerebral hemispheres and stained with cresyl violet.  

In the Hippocampal Formation, IGFBP4 immunoreactivity was also decreased in the pyramidal cells of CA1-3 areas and the granule cells of dentate gyrus.  

The entorhinal cortex (EC) projects via the perforant pathway to all subfields in the Hippocampal Formation.  

These findings are relevant to how changes in environmental context affect neuronal responses in the Hippocampal Formation, and may aid in the development of novelty-response tasks where novelty resides in open field surfaces..  

Based on reports on possible factors deciding ethanol neurotoxicity to the brain, we review developmental neurotoxicity to the dentate gyrus of the Hippocampal Formation..  

The Hippocampal Formation is anatomically and functionally related to the olfactory structures especially in rodents. The relationships between the Hippocampal Formation and the vomeronasal system are virtually unexplored.  

Some brain regions strongly involved in cognition such as the prefrontal cortex, Hippocampal Formation and corpus striatum, are densely innervated by serotonergic and dopaminergic afferents proceeding from the raphe complex and the mesocorticolimbic or nigrostriatal systems, respectively.  

The entorhinal cortex is commonly perceived as a major input and output structure of the Hippocampal Formation, entertaining the role of the nodal point of cortico-hippocampal circuits. Here, we aim to summarize recent anatomical data supporting the notion that the traditional description of the entorhinal cortex as a layered input-output structure for the Hippocampal Formation does not give the deserved credit to what this structure might be contributing to the overall functions of cortico-hippocampal networks..  

The Hippocampal Formation is critically involved for the long-term storage of various forms of information, and it is widely believed that the phenomenon of long-term potentiation (LTP) of synaptic transmission is a molecular/cellular mechanism participating in memory formation.  

RESULTS: Patients with trichotillomania showed increased grey matter densities in the left striatum, left amygdalo-Hippocampal Formation, and multiple (including cingulate, supplementary motor, and frontal) cortical regions bilaterally.  

The main telencephalic afferents to the septum arise ipsilaterally from the Hippocampal Formation, dorsolateral corticoid area, piriform cortex, amygdaloid pallium, and the ventral pallidum. The most prominent differences with previous pigeon data were found in the subregional selectivity of the Hippocampal Formation, dorsolateral corticoid area, mammillary nuclei, some dorsal thalamic nuclei, substantia nigra, and subcoeruleus nuclei in their projections to defined septal nuclei..  

To determine whether this is the case, we used immunoelectron microscopy to examine PR distribution in the Hippocampal Formation of proestrus rats. These findings suggest that some of progesterone's actions in the Hippocampal Formation may be mediated by direct and rapid actions on extranuclear PRs and that PRs are well positioned to regulate progesterone-induced changes at synapses..  

In contrast, following global forebrain ischemia changes in Manf expression were widespread in the Hippocampal Formation and more restricted in cerebral cortex.  

It is now clear that these frontal structures, through bidirectional excitatory communication with the Hippocampal Formation, also play a substantial role in long-term memory consolidation.  

Cells throughout the Hippocampal Formation are involved in processing spatial information. Nuclei in the mammillary region provide ascending influences to the Hippocampal Formation and have been implicated in influencing both hippocampal spatial and theta signals.  

While astrocytic staining remains relatively constant at all ages and regions assessed, microglial activation appears to progressively increase temporally, especially within the Hippocampal Formation.  

In the Hippocampal Formation (HF), the enkephalin opioids and estrogen are each known to modulate learning and cognitive performance relevant to drug abuse.  

The vulnerability of the transentorhinal cortex, which displays the first architectural signs of AD, may be related to its role as the entry point for an enormous amount of excitatory information, the majority from the neocortex, which passes through the Hippocampal Formation.  

Immunolabeling of pERK in control animals revealed an abundance of distinctly-labeled neurons within the Hippocampal Formation. However, in pilocarpine-treated mice during the seizure-free period, the numbers of pERK-labeled neurons were substantially decreased throughout much of the Hippocampal Formation.  

Differential long-term neurotoxicity of HIV-1 proteins in the rat Hippocampal Formation: a design-based stereological study.  

A detailed MRI-analysis showed an intact Hippocampal Formation.  

Longitudinal fiber systems in the Hippocampal Formation play an important role in propagating information to the entire septotemporal extent of the hippocampus.  

Studies of epilepsy and memory are tied by their common dependence on the Hippocampal Formation and the adjacent brain structures in the temporal lobe.  

Studies of experimental mesial temporal lobe epilepsy (mTLE) indicate that prolonged seizures in the adult not only damage the Hippocampal Formation but also dramatically stimulate neurogenesis.  

Freely-moving Tc1 mice exhibit reduced LTP 1 h after induction but normal maintenance over days in the dentate gyrus of the Hippocampal Formation.  

Our findings suggest that COMT val158met may contribute to intelligence by affecting the association between IQ and the white matter architecture in the prefrontal lobe and the Hippocampal Formation.  

Limbic structures, which include amygdala, Hippocampal Formation, septal area, prefrontal cortex and anterior cingulate gyrus serve important modulating functions.  

Detailed description of the brain size, rhinencephalon and Hippocampal Formation of the Bactrian camel is presented in our study.  

In newborn mouse brain, mNeil3 revealed a discrete expression pattern in brain regions known to harbour stem cell populations, i.e., the subventricular zone, the rostral migratory stream, and the hilar region of the Hippocampal Formation.  

We found that Akt, LIMK, and TrkB were activated throughout the dorsal Hippocampal Formation during the high-estradiol phase, proestrus.  

It is important to establish how information is transmitted through the Hippocampal Formation because of the structure's critical role in memory and spatial processing. Accordingly, processing in the Hippocampal Formation is by open rather than closed loops. Overall, the findings indicate that information can potentially be transmitted from the septal to the temporal end of the Hippocampal Formation via an ordered succession of hippocampal and entorhinal areas that form a three-dimensional spiral pathway..  

Terminally ill scrapie-infected animals exhibit nearly complete loss of cornu ammonis (CA) 1 pyramidal neurons, but few studies have focused on the neuropathological lesions of the human hippocampus in autopsied brain tissue; in particular, few findings on differences in severity of pathology between the hippocampal and paraHippocampal Formations have been obtained. In addition, differences in neuropathological severity were observed within the Hippocampal Formation.  

In this study, we examined the expression and intracellular distribution of GPR30 in the rat Hippocampal Formation.  

The locus coeruleus (LC) is the main source of noradrenergic innervations to the forebrain and the Hippocampal Formation but does not receive noradrenergic projections itself.  

5HT 1A receptor binding and receptor-effector coupling were not different in the ventral Hippocampal Formation, entorhinal or parietal cortices, or inferior colliculus. Taken together, these results suggest that perinatal arsenic exposure may disrupt the regulatory interactions between the hypothalamic-pituitary-adrenal axis and the serotonergic system in the dorsal Hippocampal Formation in a manner that predisposes affected offspring to depressive-like behavior.  

We therefore analyzed the distribution and expression of several GABA(A) receptor subunits (alpha1, alpha2, alpha 3, alpha 4, alpha 5, beta2/3, and gamma 2) immunohistochemically with specific antibodies in the Hippocampal Formation of responders, nonresponders and nonepileptic controls.  

Several recent studies have implicated reduced brain-derived neurotrophic factor (BDNF) levels in the Hippocampal Formation and frontal cortex as important contributors to the etiology of depression. In the present studies, we sought to determine whether prenatal ethanol exposure is associated with behaviors that model depression, as well as with reduced BDNF levels in the Hippocampal Formation and/or medial frontal cortex, in a mouse model of fetal alcohol spectrum disorder (FASD). Prenatal ethanol exposure was associated with decreased BDNF protein levels in the medial frontal cortex, but not the Hippocampal Formation, while total BDNF mRNA and BDNF transcripts containing exons III, IV or VI were reduced in both the medial frontal cortex and the Hippocampal Formation of prenatal ethanol-exposed mice. These results identify reduced BDNF levels in the medial frontal cortex and Hippocampal Formation as potential mediators of depressive disorders associated with FASD..  

The EC was chosen as seed region since it is the link between the neocortex and the Hippocampal Formation.  

The nonhuman primate entorhinal cortex is the primary interface for information flow between the neocortex and the Hippocampal Formation. Thus, some of the cortical inputs may be more influential on the cortically directed outputs of the Hippocampal Formation or on gating neocortical information flow into the other fields of the Hippocampal Formation rather than contributing to the perforant path inputs to other hippocampal fields..  

High-frequency field ripples occur in the rodent Hippocampal Formation and are assumed to depend on interneuron type-specific firing patterns, structuring the activity of pyramidal cells. By in vivo recording interneurons and pyramidal cells in the human Hippocampal Formation, we find that cell type-specific firing patterns and phase-locking on a millisecond timescale can be distinguished during ripples.  

CA3 and subiculum are Hippocampal Formation regions that can initiate seizure activity because each has a substantial intrinsic excitatory connectivity. Although this collateral system is sparse compared with other Hippocampal Formation regions, its unidirectionality protects against re-entrant activation of CA3 and may be physiologically significant as a relay from proximal CA1 to distal CA1..  

High-density specific binding was found in discrete areas of the brain and spinal cord, namely in the limbic system (Hippocampal Formation, septohippocampal nucleus, indusium griseum, hypothalamus, amygdaloid nuclei), superior colliculus, dorsal raphé, and substantia gelatinosa of the spinal cord.  

METHODS: Immunohistochemical staining of GAD 65/67 was performed in the orbitofrontal, anterior cingulate and dorsolateral prefrontal cortex (DLC), the entorhinal cortex (EC), the Hippocampal Formation, and the medial dorsal and lateral dorsal thalamic nuclei, with consecutive determination of GAD-immunoreactive (-ir) neuropil relative density. RESULTS: As shown by post-hoc U-tests, an increase in the relative density of GAD-ir neuropil was present in the Hippocampal Formation, specific for suicidal patients.  

The neuropathological assessment showed few neurofibrillary tangles (NFT) in the Hippocampal Formation compatible with Braak staging II, absence of amyloid deposits and other types of neurodegenerative lesions as well as preservation of neuron numbers in locus coeruleus. This finding was related to a striking paucity of Alzheimer disease (AD)-related lesions in the Hippocampal Formation. In conjunction with recent stereological analyses in cases aged from 90 to 102 years, it also points to the marked resistance of the Hippocampal Formation to the degenerative process in this age group and possible dissociation between the occurrence of slight cognitive deficits and development of AD-related pathologic changes in neocortical areas.  

The Hippocampal Formation receives extensive noradrenergic projections and expresses high levels of mineralocorticoid (MR) and glucocorticoid (GR) receptors. However, there is relatively little data describing the influence of glucocorticoids on noradrenergic receptors in the Hippocampal Formation. alpha1d adrenergic receptor (ADR) mRNA is expressed at high levels in the Hippocampal Formation, within cells that express MR or GR. The effect was specific for the Hippocampal Formation, with levels of alpha1d mRNA unaltered by ADX in the lateral amygdala, reticular thalamic nucleus, retrosplenial cortex or primary somatosensory cortex. These data indicate that alpha1d ADR mRNA expression in the Hippocampal Formation is highly sensitive to circulating levels of corticosterone, and provides further evidence for a close interaction between glucocorticoids and the noradrenergic system in the hippocampus..  

Along these lines, the purpose of our work was to analyze the relative expression of VDR mRNA in the Hippocampal Formation of rats during the three periods of pilocarpine-induced epilepsy.  

Human temporal lobe epilepsy and experimental models of this disease are associated with loss of neurons and other structural alterations in several limbic brain structures including the Hippocampal Formation and adjacent parahippocampal cortical areas.  

The aim of this work was to study the rat's Hippocampal Formation by applying the light microscopic methods. The layers of the Hippocampal Formation were differentiated.  

BACKGROUND: We previously demonstrated that shape variants of the Hippocampal Formation are more prevalent in patients with temporal lobe epilepsy (TLE) than in healthy individuals.  

We now demonstrate VGLUT2 as well as the vesicular GABA transporter (VGAT) in a subset of presynaptic terminals in the dentate gyrus of the rat Hippocampal Formation.  

The aim of the present work was to perform, by in situ hybridization, a time-course analysis of the glial cell line-derived neurotrophic factor (GDNF) and its receptor mRNA expression in two models of brain injury in the rat: (a) excitotoxic lesion by ibotenic acid injection in the Hippocampal Formation; (b) mechanical lesion by needle insertion through the cerebral cortex including the white matter of the corpus callosum.  

Thus, our data suggest that the effects of exercise on neurogenesis and other plasticity changes in the Hippocampal Formation are mediated by mechanisms that do not involve retinoid receptor activation..  

On the one hand, it is a critical link in providing the entorhinal cortex and Hippocampal Formation with cortical input, while on the other hand it receives output from these structures and projects widely by disseminating the medial temporal lobe output to the cortex. These observations reveal a further disruption of memory-related temporal neural systems in AD where pathology selectively alters both the input to the Hippocampal Formation and its output to the cortex..  

Type 2 was distinguished from type 1 by the presence of TDP-43-ir NCIs in the frontotemporal cortex, Hippocampal Formation, neostriatum and substantia nigra, and was significantly associated with dementia.  

The Hippocampal Formation is a brain system that is implicated in learning and memory. We observed a linear relationship between the current intensity used to stimulate the Hippocampal Formation and the amplitude and extension of the induced BOLD response.  

CONCLUSION: The dysfunction of CREB signaling in the central nervous system, especially in the Hippocampal Formation after predation stress may play an important role in the long-term neuropsychological sequelae following severe stress..  

The response properties of 48 right (n=24) and left (n=24) Hippocampal Formation (HF) cells were examined by recording from freely moving homing pigeons as they foraged in an open-field environment with unstable goal locations.  

The Hippocampal Formation was isolated by manual tracing.  

These results demonstrate that deterioration of neocortical connections to the Hippocampal Formation results in part from the degeneration of critical MTL and associated fiber pathways..  

In this study, we found that the expressions of Tbeta15 mRNA and protein were substantially increased in several brain regions including Hippocampal Formation and cerebral cortex, following kainic acid (KA)-evoked seizures in rat.  

The HD cells can be found throughout many portions of the Hippocampal Formation, as well as additional limbic cortical and subcortical regions. They are, however, found in various forms throughout much of the Hippocampal Formation. According to the above reasoning, lesions of the mammillary bodies should completely eliminate both HD and place/grid cells in the Hippocampal Formation. Here, we tested for both HD and place cell activity in various Hippocampal Formation sub regions following lesions of the mammillary bodies.  

These findings support the idea that the Hippocampal Formation plays an essential and possibly permanent role in fear memories..  

We have reported that prolonged red wine intake improves Hippocampal Formation oxidative status, a finding not replicated using Port wine.  

Six weeks of estradiol treatment caused an increase in choline acetyltransferase activity throughout the projection fields of the basal forebrain, including the Hippocampal Formation (14%), olfactory bulb (30%), and cerebral cortex (35%).  

It is also possible to distinguish between the grey Cerebellar Cortex and the Hippocampal Formation, due to the grey Cerebellar Cortex having a positive PC2 and the Hippocampal Formation having a negative PC2 score; this is only possible in supervised PCA with this data set because with unsupervised PCA the two regions overlap..  

Similarly, in vitro studies indicate that in immature Hippocampal Formation, the propagation of high- but not low-frequency seizures can transform a naive network into one that generates further seizures, thereby, giving an indication as to the types of seizure that are epileptogenic.  

Neuronal death and the neuroplasticity of surviving cells contribute to major phenomena: an increased hyperexcitability of the Hippocampal Formation and an increased synchronization of its principal cells. A complete transection of the Hippocampal Formation (including dentate gyrus and hippocampus proper, sparing the fimbria) results in a blockade of ictal activities spread from the generator, a reduction in their frequency and an increase in their duration. In this model of mesial temporal lobe epilepsy, longitudinally projecting axonal circuits of the dentate gyrus and hilus appear to be implicated in generation, propagation and interruption of ictal activities within Hippocampal Formation..  

Using slice preparation maintaining the neurocircuit connecting PC, EC, Hippocampal Formation and amygdala, we investigated the associative function of PC and EC with respect to sensory and motivational stimuli and the influence of the association on the neurocircuit.  

The subiculum as a part of the Hippocampal Formation is the principal target of CA1 pyramidal cell axons and serves as an interface in the information processing between the hippocampus and the neocortex.  

However, recent studies have detected androgen receptor immunoreactivity in neuronal and glial processes of the adult rat neocortex, Hippocampal Formation, and amygdala as well as in the telencephalon of eastern fence and green anole lizards.  

Subordinate male tree shrews exhibit chronic hypothalamo-pituitary-adrenal (HPA) activation as reflected in continuously elevated cortisol secretion, and structural changes in the Hippocampal Formation.  

The last few decades have seen the Hippocampal Formation at front and center in the field of synaptic transmission.  

OBJECTIVE: To investigate the expressions and distributions of N-methyl-D-aspartic acid NMDA/ NR1 and alpha-amino-3-hydroxy-5-methyl-4 isoxazolepropionic acid AMPA/GluR2 subunits in the Hippocampal Formation. RESULTS: There were widely positive expressions and basically same distributions of NR1 and GluR2 in the Hippocampal Formation of adult rats, especially in pyramidal layer of CA1 and CA3 regions and in the interneurons of hilus fascia dentata. CONCLUSION: The distributions of NMDA/NR1 and AMPA/GluR2 in the Hippocampal Formation are basically same, this suggests that they may execute cooperatively some important tasks..  

Western blotting and immunogold analysis of Hippocampal Formation indicated similar levels of GDH in the latent and chronic phases of KA injected rats and in corresponding controls. In contrast, the level of GS was increased in the latent phase compared with controls, as assessed by Western blots of whole Hippocampal Formation and subregions. The decrease in GS from latent to chronic phase was significant in whole Hippocampal Formation, dentate gyrus and CA3.  

This review focuses on the actions of caffeine on changes in structure and function in the region of the Hippocampal Formation and neocortex, which exhibit high synapse plasticity.  

Three-dimensional parametric mesh models of the hippocampus were created from manual tracings of the Hippocampal Formation.  

In the MTL, PER provides input to the Hippocampal Formation directly and via the entorhinal cortex (EC), whereas in the VVS, PER is considered to be at the top of the visual processing hierarchy of object information.  

CONCLUSION: This study points to different anatomical patterns of connectivity in the Hippocampal Formations of both hemispheres which may underlie functional asymmetries..  

Following verum, but not sham, acupuncture there was increased DMN connectivity with pain (anterior cingulate cortex (ACC), periaqueductal gray), affective (amygdala, ACC), and memory (Hippocampal Formation, middle temporal gyrus) related brain regions. Furthermore, increased DMN connectivity with the Hippocampal Formation, a region known to support memory and interconnected with autonomic brain regions, was negatively correlated with acupuncture-induced increase in a sympathetic related HRV metric (LFu), and positively correlated with a parasympathetic related metric (HFu).  

Visual object-recognition is thought to involve activation of a distributed network of cortical regions, nodes of which include the lateral prefrontal cortex, the so-called lateral occipital complex (LOC), and the Hippocampal Formation. Subdural electrodes were placed over the prefrontal cortex and LOC, and depth electrodes were placed within the Hippocampal Formation.  

We explored the interplay of excitation and inhibition in synapses between pyramidal neurons of cornu ammonis field 3 of the Hippocampal Formation (CA3) in cultured rat hippocampal slices, where activation of a single excitatory cell can readily recruit local interneurons.  

Previous WS studies have identified functional and structural abnormalities in the Hippocampal Formation, prefrontal regions crucial for amygdala regulation and social cognition, and the dorsal visual stream, notably the intraparietal sulcus (IPS).  

Indeed, most of the 5-HT receptors characterized so far, i.e., 5-HT(1) through 5-HT(7), show a regional distribution in brain areas involved in learning and memory, such as Hippocampal Formation (HF), amygdala and cortex.  

Here we show, by electrophysiological recordings in CA1 of the Hippocampal Formation of rats, that hippocampal NPY gene transfer into the intact brain does not affect basal synaptic transmission, but slightly alters short-term synaptic plasticity, most likely via NPY Y2 receptor-mediated mechanisms.  

Neurogenesis continues in the adult forebrain subventricular zone (SVZ) and the dentate gyrus of the Hippocampal Formation. Dopaminergic denervation in adult mice reduced CNTF mRNA by approximately 60%, whereas systemic treatment with the D2 agonist quinpirole increased CNTF mRNA in the SVZ and Hippocampal Formation, and in cultured astrocytes by 1.5-5 fold.  

To investigate whether n-3 polyunsaturated fatty acids (n-3 PUFAs) would promote different morphological changes in the Hippocampal Formation of rats with epilepsy, we performed an immunocytochemical study using parvalbumin (PV) and calretinin (CR) distribution as a marker. These findings demonstrate that omega-3 fatty acids prevent status epilepticus-associated neuropathological changes in the Hippocampal Formation of rats with epilepsy..  

No such correlation was apparent in the rest of the Hippocampal Formation.  

The transient forebrain ischemia enhanced Sox11 gene expression moderately in the CA1 and strongly in the DG, whereas Brn1 was selectively induced only in the CA1 of the Hippocampal Formation.  

In the Hippocampal Formation the lack of IMPACT in the dentate gyrus granule cells was striking.  

Furthermore, according to our results, POP may be involved in thalamocortical neurotransmission, memory and learning functions of the Hippocampal Formation, and GABAergic regulation of voluntary movements.  

To investigate whether the distribution of M6a correlates with neuronal structures susceptible to alterations in response to stress, we localized M6a expression in neurons of Hippocampal Formation, prefrontal cortex and cerebellum using in situ hybridization and confocal immunofluorescence microscopy.  

For the pathways that link the thalamus and the Hippocampal Formation, only a few comparable connections have been described. The reuniens nucleus of the thalamus sends some of its major cortical efferents to the Hippocampal Formation. The present study shows that cells of the Hippocampal Formation as well as cells in the reuniens nucleus are retrogradely labelled following injections of horseradish peroxidase or fluoro-gold into the rostral part of the thalamic reticular nucleus in the rat. Within the Hippocampal Formation, labelled neurons were localized in the subiculum, predominantly on the ipsilateral side, with fewer neurons labelled contralaterally. Labelled neurons were seen in the Hippocampal Formation and nucleus reuniens only after injections made in the rostral thalamic reticular nucleus (1.6-1.8 mm caudal to bregma).  

Afferents from the perirhinal cortex (PRh) form a major input to the Hippocampal Formation, which is known to be involved in sexual behavior in rodents.  

In particular, mUBPy was strongly expressed in the Hippocampal Formation, septal region, ventral pallidum, preoptic nucleus, periventricular nucleus of hypothalamus, compact part of the substantia nigra, ventral tegmental area, cochlear nucleus and granular cell layer of cerebellum.  

Prior to dementia, when individuals are beginning to manifest signs and symptoms of memory impairment, the Hippocampal Formation and other components of the MTL memory system exhibit substantial functional abnormalities during memory task performance.  

METHODS: Rhesus monkeys (Macaca mulatta) with excitotoxic lesions of the Hippocampal Formation and unoperated control animals were assessed on two different types of emotional processing: defensive reactions to a potential predator (experiment 1) and ability to update the value of positive reinforcers, in this case food (experiment 2). CONCLUSIONS: These findings dissociate the hippocampus and perirhinal cortex in fear expression and specifically implicate the Hippocampal Formation in generating responses to stimuli that are potentially threatening..  

In temporal lobe epilepsy (TLE), the seizure origin typically involves the Hippocampal Formation.  

The Hippocampal Formation was intensely labeled.  

CB1 receptor level and CB1/G-protein coupling were significantly reduced by THC exposure in the amygdala (Amyg), ventral tegmental area (VTA) and nucleus accumbens (NAc) of female rats, whereas male rats had significant alterations only in the amygdala and Hippocampal Formation. Only female rats had low CREB activity in the Hippocampal Formation and prefrontal cortex and high activity in the NAc paralleled by increases in dynorphin expression.  

Stress and depression cause structural changes in the Hippocampal Formation.  

Furthermore, in the search for a morphological correlate of the seizures, the Hippocampal Formation was examined histologically. In addition to the known demyelination of the corpus callosum, massive demyelination was found in the Hippocampal Formation. The present data suggest a potential role of the Hippocampal Formation for seizures occurring as a consequence of neuronal damage secondary to CNS demyelination..  

The dentate gyrus, an important anatomic structure of the Hippocampal Formation, is one of the major areas in which neurogenesis takes place in the adult mammalian brain.  

The Hippocampal Formation (HF) plays a key role in novelty detection, but the mechanisms remain unknown.  

One of the most studied of these regions is the dorsal Hippocampal Formation, which governs the formation of spatial and episodic memories. This review summarizes work conducted in our laboratory and others toward identifying estrogen's actions in the Hippocampal Formation, and the mechanisms for these actions. The effects of estrogen in the Hippocampal Formation that lead to modulation of hippocampal function include effects on cell morphology, synapse formation, signaling, and excitability that have been studied in laboratory mice, rats, and primates.  

This variant is associated with differences in the volume of the Hippocampal Formation and with anxiety and depression-related phenotypes.  

In the Hippocampal Formation, Ca(v)1.2 (L-type) voltage-gated Ca(2+) channels mediate Ca(2+) signals that can trigger long-term alterations in synaptic efficacy underlying learning and memory. To define the subcellular substrates underlying Ca(v)1.2 Ca(2+) signals, we analyzed the localization of Ca(v)1.2 in the Hippocampal Formation by using antibodies against the pore-forming alpha(1)-subunit of Ca(v)1.2 (alpha(1)1.2). These findings provide the first detailed ultrastructural analysis of Ca(v)1.2 localization in the brain and support functionally diverse roles of these channels in the Hippocampal Formation..  

The Hippocampal Formation is a key structure in memory formation and consolidation.  

The neuropathological assessment showed few neurofibrillary tangles (NFT) in the Hippocampal Formation compatible with Braak staging II, absence of amyloid deposits and other types of neurodegenerative lesions as well as preservation of neuron numbers in locus coeruleus. This finding was related to a striking paucity of Alzheimer disease (AD)-related lesions in the Hippocampal Formation. In conjunction with recent stereological analyses in cases aged from 90 to 102 years, it also points to the marked resistance of the Hippocampal Formation to the degenerative process in this age group and possible dissociation between the occurrence of slight cognitive deficits and development of AD-related pathologic changes in neocortical areas.  

Although several recent reports suggest a latent neurogenic capacity in multiple brain regions, the two major neurogenic niches that retain the ability to generate substantial numbers of new neurons in adult life are the subventricular zone (SVZ) lining the lateral ventricles and the subgranular zone (SGZ) in the Hippocampal Formation.  

The dentate gyrus, a region of the Hippocampal Formation, displays the highest level of plasticity in the brain and exhibits neurogenesis all through life.  

Western blot study showed that in the Hippocampal Formation with ischemic preconditioning, preconditioning prevented the decline of these protein levels from 1 day to 7 days after the second lethal ischemia (ANOVA test, P>0.05).  

Since astroglial gap junction (GJ) coupling is known to influence neurodegenerative processes, the question arose whether persistent BDV infection influences astroglial connexins (Cx) Cx43 and Cx30 in the Hippocampal Formation (HiF) of Lewis rats.  

Here, we investigated short-term memory for single features and feature associations in three humans with post-surgical lesions affecting the right Hippocampal Formation and in 10 healthy controls. These findings show that the Hippocampal Formation plays a significant role for short-term memory of simple visuo-spatial associations, and suggest a specialization of MTL sub-regions for associative memory..  

The dentate gyrus is the main target for cortical inputs to the Hippocampal Formation and is particularly strongly controlled by synaptic inhibition.  

The Hippocampal Formation plays an essential role in associative learning like passive avoidance (PA) learning. It has been shown; orexin-containing terminals and orexin receptors densely are distributed in the Hippocampal Formation.  

Neurokinin-1 (NK-1) receptors and brain-derived neurotrophic factor (BDNF), known neuromediators of hyperalgesia and spinal central sensitization, have also been implicated in the plasticity and neurodegeneration occurring in the Hippocampal Formation during exposures to various stressors.  

A consistent reduction of N-acetyl-aspartate (NAA) was reported in the Hippocampal Formation among bipolar disorder (BD) patients, along with an increment in frontal Glu.  

We examined dysbindin-1 mRNA in the Hippocampal Formation of patients with schizophrenia and found reduced expression in dentate granule and polymorph cells and in hippocampal field CA3, but not in CA1. Our results indicate that previously reported dysbindin-1 protein reductions may be due in part to decreased dysbindin-1 mRNA and that reduced dysbindin-1 may contribute to Hippocampal Formation synaptic pathology in schizophrenia..  

Magnetic resonance revealed bilateral symmetric hyperintense lesions in the basal ganglia, temporal lobe and Hippocampal Formation compatible with ODS.  

Our aim is to assess and quantify the exact effects of the induction of long term potentiation (LTP) on tonic inhibition and facilitation in a neural circuit within the Hippocampal Formation of neonatal rats. It is known that such modulation influences the gating of neuronal transmission into and through the Hippocampal Formation; and, thereby, may play an important role in the development of learning and memory both in early life and throughout adulthood.  

The analyzed EEG signals were consisted of five sets (set A-healthy volunteer, eyes open; set B-healthy volunteer, eyes closed; set C-seizure-free intervals of five patients from Hippocampal Formation of opposite hemisphere; set D-seizure-free intervals of five patients from epileptogenic zone; set E-epileptic seizure segments).  

New neurons continue to be generated in two privileged areas of the adult brain: the dentate gyrus of the Hippocampal Formation and the olfactory bulb.  

In this model, grid cell activity in the dorsocaudal medial entorhinal cortex (dMEC) [ 28] results from the operation of a long-distance path integration system located outside the Hippocampal Formation, presumably in retrosplenial and/or parietal cortex.  

To clarify the specific contribution of the medial temporal lobe structures in spatial memory, we tested monkeys (Macaca mulatta) with sham operations and with lesions of either the Hippocampal Formation, areas TH/TF or perirhinal cortex on two versions of the visual-paired comparison task, measuring Spatial Location, and Object-in-Place associations. The data showed that the Hippocampal Formation, areas TH/TF, and perirhinal cortex appear to contribute interactively to object and spatial memory processes..  

The present set of experiments assessed the effects of acute or repeated stress on GR mRNA expression in the dorsal and ventral Hippocampal Formation either before or after pubertal maturation in male rats. We found that acute stress results in a significant decrease in GR mRNA in the CA1 pyramidal cell layer and dentate gyrus in the dorsal and ventral Hippocampal Formation of both prepubertal and adult males.  

OBJECTIVE: To study Abeta-related neurotoxicity by means of functional imaging maps of the Hippocampal Formation in human patients and mouse models.  

These representations are thought to depend on the Hippocampal Formation, particularly those that are independent of the navigator (allocentric representations).  

During retrieval, the left Hippocampal Formation showed higher activity for successful than for unsuccessful spatial context retrieval as well as an interaction between age and spatial context judgement.  

Here, we report that normal aging in rodents and primates is accompanied by accumulation of Reelin-enriched proteinous aggregates in the Hippocampal Formation that are related to the loss of Reelin-expressing neurons.  

Double immunofluorescence analysis revealed that addicsin was expressed in the somata of principal neurons in the CNS such as the pyramidal cells and gamma-aminobutyric acid (GABA)-ergic interneurons scattered in the Hippocampal Formation. Furthermore, the protein showed pre-synaptic localization in the stratum lucidum of the CA3 field of the Hippocampal Formation.  

Neuronal damage, activation of the TLR4 signaling pathway, expression of pro-inflammatory cytokines and activation of the PI3K/Akt signaling pathway in the Hippocampal Formation (HF) were assessed in wild type (WT) mice and TLR4 knockout (TLR4(-/-)) mice after GCI/R. GCI/R increased expression of TLR4 protein in the Hippocampal Formation (HF) and other brain structures in WT mice.  

More detailed in vivo studies of the Hippocampal Formation, investigating subtle abnormalities such as end folium sclerosis, and the neocortex are now possible and may increase the diagnostic yield of MRI..  

First, fMRI data were analysed at the group level to identify the regions of the Hippocampal Formation that were engaged by this memory task. In addition, an exploratory whole brain analysis produced convergent results, demonstrating that the Hippocampal Formation was the only brain region where activation predicted cognitive decline.  

We present a model for the self-organized formation of place cells, head-direction cells, and spatial-view cells in the Hippocampal Formation based on unsupervised learning on quasi-natural visual stimuli.  

One region that has received a great deal of attention is the Hippocampal Formation due to the increased incidence of impaired spatial learning and memory with age. The Hippocampal Formation is also highly susceptible to Alzheimer's disease, ischemia/hypoxia, and seizure generation, the three most common aging-related neurological disorders. While data reveal that the dentate gyrus plays a key role in hippocampal function and dysfunction, the majority of electrophysiological studies that have examined the effects of age on the Hippocampal Formation have focused on CA3 and CA1.  

In particular, at the gate of the Hippocampal Formation, the dentate gyrus possesses a set of unusual properties, which selectively evolved for the task of code transformation between cortical afferents and the hippocampus. These evolutionarily conserved anatomical features enable the dentate gyrus to translate the noisy signal of the upstream cortical areas into the sparse and specific code of Hippocampal Formation, which is indispensable for the efficient storage and recall of multiple, multidimensional memory items.  

Being part of the Hippocampal Formation, the dentate gyrus is naturally involved in these mechanisms and as such, this structure is also a critical target for the activational effects of sex steroids.  

Recent evidence indicates that opiates and opioids also modulate other processes in the Hippocampal Formation, including adult neurogenesis, the actions of gonadal hormones, and development of neonatal transmitter systems..  

This strong influence is due to the fact that the majority of the extrinsic afferents terminate on a relatively small, but specific, populations of neurons that are able to control large areas of the Hippocampal Formation..  

This paper provides a comprehensive description of the organization of projections from the entorhinal cortex to the dentate gyrus, which together with projections to other subfields of the Hippocampal Formation form the so-called perforant pathway.  

The dentate gyrus is a simple cortical region that is an integral portion of the larger functional brain system called the Hippocampal Formation.  

This study shows that two whole isolated preparations from the young mouse, the neocortical 'slab' and the Hippocampal Formation, are useful for imaging studies requiring both global monitoring using light transmittance (LT) imaging and high resolution cellular monitoring using 2-photon laser scanning microscopy (2PLSM).  

Here we report that, when given into dorsal CA1 immediately but not 180 min after daily nonreinforced retrieval sessions, SP60015, a specific inhibitor of the mitogen-activated protein kinase, c-Jun N-terminal kinase, impaired IA memory extinction in a dose-dependent manner without producing any motor or perceptual impairment or damaging the Hippocampal Formation.  

So far, only a few studies have focused on the Hippocampal Formation as a potential target for the effects induced by MDMA. We found that MDMA, at very low doses, comparable with those self-administered by humans, produces acute oxidative stress and DNA single and double-strand breaks, which persist together with long-lasting metabolic changes in the Hippocampal Formation.  

The different CA areas of the Hippocampal Formation all displayed equivalent degrees of cell death but the entorhinal areas showed the most severe degree of cell degeneration.  

We conclude that (i) various areas of the Hippocampal Formation respond differently to ionic replacements; (ii) K(+) interacts with other ions to protect cells in ARA; and (iii) DIDS has a substantial protective effect in ARA by blocking DIDS-sensitive membrane exchangers or by interfering with intracellular signaling pathways..  

This learning is essential for visual search and discrimination performance and is reliant upon a well-defined neural circuit in the brain that includes the prefrontal cortex and the Hippocampal Formation.  

The Hippocampal Formation is believed to be critical for the encoding, consolidation, and retrieval of episodic memories.  

In the mental navigation task bilateral activation of the Hippocampal Formation was observed.  

Brain extracts from Hippocampal Formation, entorhinal cortex, and neocortex, were analyzed by (13)C and (1)H magnetic resonance spectroscopy to quantify (13)C labeling and concentrations of metabolites, respectively. The amount and (13)C labeling of glutamate were reduced in the Hippocampal Formation and entorhinal cortex of epileptic rats. Additionally, mitochondrial dysfunction was detected in surviving glutamatergic neurons in the Hippocampal Formation. This mechanism was not operative in the Hippocampal Formation, where glutamine labeling was decreased.  

This study adapted a reward assessment paradigm, previously conducted with rhesus monkeys (Macaca mulatta) in the controlled environment of a Wisconsin General Testing Apparatus (WGTA) [ Machado CJ, Bachevalier J (2007) The effects of selective amygdala, orbital frontal cortex or Hippocampal Formation lesions on reward assessment in nonhuman primates.  

Besides the Hippocampal Formation, other subpopulations of neurons in extra-hippocampal brain areas have been also shown recently to be sensitive to changes in the corticosteroid milieu.  

We conclude that electrical stimulation of the epileptic Hippocampal Formation can control mesial temporal seizures.  

Anatomical targets such as the thalamus (centromedian nucleus, anterior thalamus, mamillary body and mamillothalamic tracts), the subthalamic nucleus, the caudate nucleus and direct stimulation of the Hippocampal Formation have been successfully investigated.  

Three-dimensional parametric mesh models were created from manual tracings of the Hippocampal Formation.  

Inflammatory response was confined to the ipsilateral cortex and Hippocampal Formation, predominating in the contusion and pericontusional cortex.  

In the Hippocampal Formation samples of left hemispheres, the levels of malondialdehyde (MDA) and superoxide dismutase (SOD) were measured and the number of apoptotic neurons was counted by 'terminal transferase dUTP nick end labelling' (TUNEL) assay in the right Hippocampal Formation. The number of apoptotic neurons (TUNEL+) in the CA1, CA2, CA3 and dentate gyrus areas of rabbits' Hippocampal Formation were significantly increased in Group B rabbits compared with the control group. CONCLUSION: These findings suggest that cigarette smoking induces apoptosis in the Hippocampal Formation of rabbits and CAPE has a protective role against this induction..  

A similar progression is described for development of the temporal lobe model of schizophrenia, moving from research on the temporal cortex and language processing to the Hippocampal Formation and long-term memory (LTM).  

This resulted in the lack of the entire Hippocampal Formation.  

In this study, we aimed to compare direct and indirect quantification approaches for Hippocampal Formation changes in patients with mild cognitive impairment and Alzheimer's disease (AD). Direct measurement of the Hippocampal Formation was performed on coronal slices using a standardized protocol, while indirect temporal horn volume (THV) was calculated using a watershed algorithm-based software package (MeVis, Germany).  

In some cases, tau pathology in the Hippocampal Formation coexisted with glial tau pathology in the frontal cortex.  

Here, we examined the expression of latent inhibition (LI)--a form of selective learning that is sensitive to a number of manipulations targeted at the Hippocampal Formation, in alpha 5(H105R) mutant mice with reduced levels of hippocampal alpha 5-containing GABA(A) receptors.  

Glycerol significantly increased the density of neuronal apoptosis in the dentate gyrus of the Hippocampal Formation.  

We conclude that low dose neonatal DOM produces cytoarchitectural changes indicative of abnormal development and/or synaptic plasticity that are progressive with age and show regional variation within the Hippocampal Formation..  

The impairment of learning and memory is one of the most powerful and least understood effects of marijuana although the Hippocampal Formation appears to be one CNS region mediating these effects.  

In this study whole-cell, patch-clamp experiments were carried out in acute rat brain slices to investigate I(NaR) expression and properties in several neuronal populations of the parahippocampal region and Hippocampal Formation. Our results show that the parahippocampal region and part of the Hippocampal Formation are sites of major I(NaR) expression, and provide a new basis for further studies on the molecular correlates of I(NaR)..  

In addition, several structures in the tree shrew brain were labeled, among them the pars tuberalis, the cerebellum, structures of the Hippocampal Formation and dopaminergic areas such as the caudate putamen and nucleus accumbens, providing other potential targets of psychosocial stress in the tree shrew, in addition to the SCN.  

A few non-endocrine tissues displayed moderate immunoreactivity; these included all tubules and collecting ducts in the kidney, myocardial and endocardial layers of the heart, the Hippocampal Formation, pyramidal neurons in the cortex and the ductal epithelium of the mammary gland.  

Magnetic resonance imaging volumetric measurements were performed of the total cerebral and Hippocampal Formation volumes in 30 patients with idiopathic partial epilepsy between 3 to 18 years old.  

FGFR3 is expressed in the brain during development and plays a role in Hippocampal Formation, and FGFR3 mutations could cause cerebral malformations in hypochondroplasia.  

An adult-like expression of CART peptide and calbindin in the Hippocampal Formation was detectable at P30.  

Several findings relate the Hippocampal Formation to the behavioural consequences of stress.  

RESULTS: GFAP-immunoreactive cells in the control mice were observed mainly within Hippocampal Formation, piriform, entorhinal cortex, septum, striatum, amygdaloid nucleus, subcortical white matter, as well as in the main fiber tracts.  

In the adult mammalian brain, multipotent stem or progenitor cells involved in reproduction of neurons and glial cells have been well investigated only in very restricted regions; the subventricular zone of the lateral ventricle and the dentate gyrus in the Hippocampal Formation.  

It has been well established that the Hippocampal Formation plays a critical role in the formation of memories. Whole-brain and region of interest (ROI) analyses revealed that the anterior Hippocampal Formation showed increased activation for subsequently remembered face-name associations compared with pairs that were forgotten. In contrast, the posterior Hippocampal Formation showed activation above baseline during attempted encoding of face-name pairs, but no evidence of differential activation based on subsequent memory. These data provide evidence for functional specialization within the Hippocampal Formation based on the associative nature of the stimuli and subsequent memory..  

Today, several studies have showed the relevance of neurogenesis in the Hippocampal Formation.  

In the present study we aimed to determine the topographical and laminar characteristics of cingulate projections to the parahippocampal region and Hippocampal Formation in the rat, using the anterograde tracers Phaseolus vulgaris-leucoagglutinin and biotinylated dextranamine. The results show that all areas of the cingulate cortex project extensively to the parahippocampal region but not to the Hippocampal Formation.  

Finally, the brains of the animals were analyzed for histological lesions in the Hippocampal Formation.  

Hippocampal Formation plays a prominent role in episodic memory formation and consolidation.  

Pathological changes in human TLE tissue are multiple and relate to structural and cellular reorganization of the Hippocampal Formation, selective neurodegeneration, and acquired changes of expression and distribution of neurotransmitter receptors and ion channels, underlying modified neuronal excitability.  

It is commonly accepted that stress may induce brain damage, especially in Hippocampal Formation, but the mechanisms that cause such damage are not well understood.  

The effect of posterior hypothalamic (PH) microinjections of GABAA and GABAB agonists (muscimol and baclophen, respectively) and antagonists (bicuculline and 2-OH saclophen) on spontaneous, sensory and electrically induced Hippocampal Formation (HPC) theta EEG activity was investigated in freely behaving cats.  

These results suggest that (1) KA-induced alterations of nocifensive behaviors are related to the neuronal death of the Hippocampal Formation, especially CA3 pyramidal neurons and (2) nocifensive behaviors induced by formalin, acetic acid, SP, glutamate, and pro-inflammatory cytokines were modulated in a different manner..  

Finally, this is the first study indicating that the Hippocampal Formation is involved in the assessment of familiar nonfoods, but not in judging the current value of unconditioned and conditioned reinforcers..  

This experimental study presents the effects of ASU on oxidant/antioxidant systems and the number of apoptotic neurons of Hippocampal Formation after ischemia and reperfusion.  

Therefore, the aim of the present work was to investigate if inhibition of NO formation would change synaptophysin mRNA expression in the Hippocampal Formation.  

The Hippocampal Formation (HPC) mediates processes associated with learning, memory, anxiety and fear.  

Stereological procedures (the Cavalieri principle together with the physical disector method) were utilized to estimate the total number of pyramidal and granule cells in defined regions of the Hippocampal Formation. These results show that even moderate exposure to cocaine during the late gestation and early postnatal period in rats is a potent teratogen and can markedly influence the development of neurons in the Hippocampal Formation..  

This phenomenon, known as the spacing effect, was explored with respect to its effect on learning and neurogenesis in the adult dentate gyrus of the Hippocampal Formation.  

RESULTS: In both patients with PD and healthy controls, olfactory stimulation activated brain regions relevant for olfactory processing (ie the amygdaloid complex, lateral orbitofrontal cortex, striatum, thalamus, midbrain and the Hippocampal Formation).  

In three patients, equivocal marginal DWI hyperintensity was noted in the Hippocampal Formation.  

[ View All ]