Altered functional connectivity of the marginal division in Parkinson's disease with mild cognitive impairment: A pilot resting-state fMRI study.

BACKGROUND: The marginal division (MrD) is an important subcortical center involved in learning and memory. Mild cognitive impairment (MCI) is commonly seen in patients with Parkinson's disease (PD), but the neurobiological basis is yet to be elucidated. PURPOSE: To use resting-state functional magnetic resonance imaging (rs-fMRI) to explore the altered functional connectivity (FC) of the MrD in patients with PD-MCI. STUDY TYPE: Prospective pilot study. POPULATION: Twenty-five patients with PD-MCI; 25 PD patients and no cognitive impairment (PD-NCI); and 25 healthy control (HC) participants. SEQUENCE: 3.0 T GE Healthcare MRI scanner; three-dimensional T1 -weighted fast spoiled gradient recalled echo (3D T1 -FSPGR); rs-fMRI. ASSESSMENT: The MrD was defined using manual delineation, which was the seed point to compute the FC to examine correlations between low-frequency fMRI signal fluctuations in MrD and the whole brain. STATISTICAL TESTS: Between-group comparisons of the rs-fMRI data were computed using two-sample t-tests in a voxelwise manner after controlling for age and sex, to determine the brain regions that showed significant differences in FC with the bilateral MrDs. Correlation analyses were performed for FC values and cognitive abilities in patients with PD. RESULTS: In the PD-MCI group, compared with the PD-NCI group, we observed lesser FC between the MrD bilaterally and right putamen, left insula, left cerebellum, and left thalamus; greater FC between the MrD bilaterally and left middle cingulate cortex, left middle frontal gyrus, left superior frontal gyrus, left supplementary motor area, and left middle/inferior occipital gyrus. Moreover, the strength of FC between the MrD and regions that showed differences between the PD-MCI and PD-NCI groups was significantly correlated with neuropsychological scores in patients with PD. DATA CONCLUSION: The current study suggests that MrD dysfunction may contribute to MCI in PD. However, the mechanisms underlying this process require further investigation. Level of Evidence 1. Technical Efficacy Stage 2. J. Magn. Reson. Imaging 2019;50:183-192.

Comparison of microRNA expression in hippocampus and the marginal division (MrD) of the neostriatum in rats.

BACKGROUND: MicroRNAs (miRNAs), a class of highly conserved small non-coding RNA molecules, are known to play essential roles in central nervous system (CNS) by causing post-transcriptional gene silencing. There is much evidence that miRNAs have specific temporal and spatial expression patterns in the mammal brain, but little is known about the role of the region specificity for the gene regulatory networks of the brain. This study represents the first attempt to perform a profiling analysis of the differential expression of miRNAs between hippocampus and the Marginal division (MrD) of the neostriatum in the rat brain. RESULTS: Microarray was used to detect the expression of 357 miRNAs in hippocampus and the MrD from three rats. A short-list of the most dysregulated 30 miRNAs per rat was generated for data analysis, and the miRNAs that were represented in two or three short-lists were then further analyzed. Quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR) was employed to validate the aberrantly expressed miRNAs obtained from the miRNA microarray analysis. A family of 11 miRNAs demonstrated differential expression between the MrD and hippocampus in more than one rat. Amongst these, miR-383 was differentially expressed in all three rats and up-regulated to the largest degree in rat one, and the ten other miRNAs, let-7d*, miR-181b, miR-187, miR-195, miR-214, miR-382, miR-411, miR-466b, miR-592 and miR-1224 were differentially expressed in at least two rats. Of these ten, besides miR-382 and miR-411 which were up-regulated in one rat and down-regulated in another, the other eight miRNAs retained a uniform direction of regulation (up-regulation or down-regulation) between different specimens. When further examined by RT-PCR, the aberrantly expressed miRNAs, except miR-383 and let-7d*, demonstrated differential expression that significantly correlated with the microarray findings. CONCLUSION: This study reported that the miRNA expression patterns in MrD was distinct from that of Hip, suggesting the role of miRNAs in the learning and memory function of the MrD probably different from hippocampus.

Immunohistochemical localization of mu opioid receptor in the marginal division with comparison to patches in the neostriatum of the rat brain.

BACKGROUND: Mu opioid receptor (MOR), which plays key roles in analgesia and also has effects on learning and memory, was reported to distribute abundantly in the patches of the neostriatum. The marginal division (MrD) of the neostriatum, which located at the caudomedial border of the neostriatum, was found to stain for enkephalin and substance P immunoreactivities and this region was found to be involved in learning and memory in our previous study. However, whether MOR also exists in the MrD has not yet been determined. METHODS: In this study, we used western blot analysis and immunoperoxidase histochemical methods with glucose oxidase-DAB-nickel staining to investigate the expression of MOR in the MrD by comparison to the patches in the neostriatum. RESULTS: The results from western blot analyses revealed that the antibody to MOR detected a 53 kDa protein band, which corresponded directly to the molecular weight of MOR. Immunohistochemical results showed that punctate MOR-immunoreacted fibers were observed in the "patch" areas in the rostrodorsal part of the neostriatum but these previous studies showed neither labelled neuronal cell bodies, nor were they shown in the caudal part of the neostriatum. Dorsoventrally oriented dark MOR-immunoreactive nerve fibers with individual labelled fusiform cell bodies were firstly observed in the band at the caudomedial border, the MrD, of the neostriatum. The location of the MOR-immunoreactivity was in the caudomedial border of the neostriatum. The morphology of the labelled fusiform neuronal somatas and the dorsoventrally oriented MOR-immunoreacted fibers in the MrD was distinct from the punctate MOR-immunoreactive diffuse mosaic-patterned patches in the neostriatum. CONCLUSIONS: The results indicated that MOR was expressed in the MrD as well as in patches in the neostriatum of the rat brain, but with different morphological characteristics. The punctate MOR-immunoreactive and diffuse mosaic-patterned patches were located in the rostrodorsal part of the neostriatum. By contrast, in the MrD, the dorsoventrally parallel oriented MOR-immunoreactive fibers with individual labelled fusiform neuronal somatas were densely packed in the caudomedial border of the neostriatum. The morphological difference in MOR immunoreactivity between the MrD and the patches indicated potential functional differences between them. The MOR most likely plays a role in learning and memory associated functions of the MrD.

The role of substance P in the marginal division of the neostriatum in learning and memory is mediated through the neurokinin 1 receptor in rats.

Substance P (SP) is a neuropeptide that plays an important role in inflammation, respiration, pain, aggression, anxiety, and learning and memory mainly through its high affinity neurokinin 1 receptor (NK1R). The marginal division (MrD) is a pan-shaped subdivision in the caudomedial margin of the neostriatum in the mammalian brain and is known to be involved in learning and memory. We studied the expression of SP, NK1R and NK1R mRNA in the rat striatum by immunohistochemistry, immunofluorescence and in situ hybridization, and found that the levels of SP, NK1R protein and NK1R mRNA were high in the cell bodies, fibers and terminals of neurons in the neostriatum, especially in the MrD. Knocking down NK1R activity in the MrD by using an antisense oligonucleotide against NK1R mRNA inhibited learning and memory in a Y-maze behavioral test. Our results show that NK1R mediates the role of SP in the MrD in learning and memory.

[A study on the neuronal mechanism of retrieval of long-term digital memory in human by functional magnetic resonance imaging].

To investigate the neuronal mechanism of retrieval of long-term digital memory in healthy volunteers, functional magnetic resonance imaging (fMRI) technique was used in the study. Twenty-two right-handed volunteers were subjected to a long-term digital memory test with block-design. The memory task and control task were adopted in the experiment alternatively. The fMRI data were recorded by a Siemens 1.5T MR machine and analyzed by SPM99. The activated brain regions were shown in the Talairach coordinate. The results showed that the Brodmann's area (BA) 9 region in left middle frontal gyrus was the most activated cortex during the long-term digital memory task. The left medial frontal gyrus, left inferior frontal gyrus, right inferior frontal gyrus, cingulate gyrus, left inferior parietal lobule, left superior parietal lobule, right superior parietal lobule, right middle temporal gyrus, left lingual gyrus, left middle occipital gyrus, right middle brain, cerebellum and right caudate nucleus tail were also involved. The activation in cortices showed obvious left predominance. It is suggested that a series of brain regions with left predominance are involved in long-term digital memory. Left lateral frontal cortex would be the most important structure for information extraction, while the other cortices and their connections may be important for processing and long-term storage of digital information.

G-CSF attenuates neuroinflammation and neuronal apoptosis via the mTOR/p70SK6 signaling pathway in neonatal Hypoxia-Ischemia rat model.

BACKGROUND: Hypoxic-ischemic encephalopathy (HIE) is an important cause of permanent damage to the central nervous system, associated with long-lasting neurological disabilities and neurodevelopmental impairment in neonates. Granulocyte-colony stimulating factor (G-CSF) has been shown to have neuroprotective activity in a variety of experimental brain injury models and G-CSF is a standard treatment in chemotherapeutic-induced neutropenia. The underlying mechanisms are still unclear. The mTOR (mammalian target of rapamycin) signaling pathway is a master regulator of cell growth and proliferation in the nervous system. However, the effects of G-CSF treatment on the mTOR signaling pathway have not been elucidated in neonates with hypoxic-ischemic (HI) brain injury. Our study investigated the neuroprotective effect of G-CSF on neonates with hypoxic-ischemic (HI) brain injury and the possible mechanism involving the mTOR/p70S6K pathway. METHODS: Sprague-Dawley rat pups at postnatal day 7 (P7) were subjected to right unilateral carotid artery ligation followed by hypoxic (8% oxygen and balanced nitrogen) exposure for 2.5 h or sham surgery. Pups received normal saline, G-CSF, G-CSF combined with rapamycin or ethanol (vehicle for rapamycin) intraperitoneally. On postnatal day 9 (P9), TTC staining for infarct volume, and Nissl and TUNEL staining for neuronal cell injury were conducted. Activation of mTOR/p70S6K pathway, cleaved caspase-3 (CC3), Bax and Bcl-2 and cytokine expression levels were determined by western blotting. RESULTS: The G-CSF treated group was associated with significantly reduced infarction volume and decreased TUNEL positive neuronal cells compared to the HI group treated with saline. The expression levels of TNF-α and IL-1ß were significantly decreased in the G-CSF treated group, while IL-10 expression level was increased. The relative immunoreactivity of p-mTOR and p-p70S6K was significantly reduced in the HI group compared to sham. The HI group treated with G-CSF showed significant upregulated protein expression for p-mTOR and p-p70S6K levels compared to the HI group treated with saline. Furthermore, G-CSF treatment increased Bcl-2 expression levels and decreased CC3 and Bax expression levels in the ipsilateral hemispheres of the HI brain. The effects induced by G-CSF were all reversed by rapamycin. CONCLUSION: Treatment with G-CSF decreases inflammatory mediators and apoptotic factors, attenuating neuroinflammation and neuronal apoptosis via the mTOR/p70S6K signalling pathway, which represents a potential target for treating HI induced brain damage in neonatal HIE.

[The brain mechanism of memory encoding and retrieval: a review on the fMRI studies].

Memory encoding and memory retrieval are two important processes of the memory. The main results of studies on the neural basis of the memory encoding and memory retrieval by functional magnetic resonance image (fMRI) technique were summarized in this review. The neural basis of memory encoding and retrieval phases varies with different materials, memory types, and age stages. It means that the neural networks of these memory activities are separate. The functional locations of the activated brain areas during memory encoding and during memory retrieval phases are overlapped with distinction. The activated brain areas of memory encoding mainly locate in the prefrontal lobe, the temporal lobe, the parietal lobe, the anterior hippocampus, the thalamus, and the basal ganglia (including the striatum and the marginal division of the striatum). The activated brain areas of memory retrieval mainly locate in the prefrontal lobe, the temporal lobe, the entorhinal cortex, the perirhinal cortex, the posterior hippocampus, the thalamus, and the basal ganglia. The anterior hippocampus is mainly activated during the encoding phase, whereas posterior hippocampus is mainly activated during the retrieval phase. The intensity of the activated cerebral cortex regions during the encoding phase is stronger than that during the retrieval phase, whereas the opposite activated pattern is found in the subcortical structures, mainly the basal ganglia and thalamus, during the two phases. It seems that the stimulation might activate certain cerebral cortex areas during the memory encoding phase, then the information is transported to the subcortical structures and comes back to the cerebral cortex to complete the memory retrieval phase. The encoding and retrieval phases of the memory are supposed to be accomplished by a neural circuit among the cerebral cortex, basal ganglia, thalamus and cerebral cortex, rather than the cerebral cortex only.

A New Neural Pathway from the Ventral Striatum to the Nucleus Basalis of Meynert with Functional Implication to Learning and Memory.

The cholinergic neurons in the nucleus basalis of Meynert (NBM) are among the first group of neurons known to become degenerated in Alzheimer's disease, and thus the NBM is proposed to be involved in learning and memory. The marginal division (MrD) of the striatum is a newly discovered subdivision at the ventromedial border of the mammalian striatum and is considered to be one part of the ventral striatum involved in learning and memory. The present study provided evidence to support the hypothesis that the MrD and the NBM were structurally connected at cellular and subcellular levels with functional implications in learning and memory. First, when wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP) was stereotaxically injected into the NBM, fusiform neurons in the MrD were retrogradely labeled with WGA-HRP gray-blue particles and some of them were double stained in brown color by AchE staining method. Thus, cholinergic neurons of the MrD were shown to project to the neurons in the NBM. Second, in anterograde tract-tracing experiments where WGA-HRP was injected to the MrD, the labeled WGA-HRP was found to be anterogradely transported in axons from the MrD to the synaptic terminals with dendrites, axons, and perikaryons of the cholinergic neurons in the NBM when observed under an electronic microscope, indicating reciprocal structural connections between the MrD and the NBM. Third, when bilateral lesions of the MrD were injured with kainic acid in rats, degenerative terminals were observed in synapses of the NBM by an electronic microscope and severe learning and memory deficiency was found in these rats by the Y-maze behavioral test. Our results suggest reciprocal cholinergic connections between the MrD of the ventral striatum and the NBM, and implicate a role of the MrD-NBM pathway in learning and memory. The efferent fibers of cholinergic neurons in the NBM mainly project to the cortex, and severe reduction of the cholinergic innervation in the cortex is the common feature of Alzheimer's patients. The newly discovered cholinergic neural pathway between the MrD of the ventral striatum and the NBM is supposed involved in the memory circuitries of the brain and probably might play a role in the pathogenesis of the Alzheimer's disease.

[Activated brain areas during simple and complex mental calculation--a functional MRI study].

Functional magnetic resonance imaging (fMRI) was used to study the activated brain areas of human during simple and complex digital calculation, and to investigate the role of cortical and subcortical structures involved in the mental calculation. Sixteen right-handed healthy volunteers performed mental calculation of simple and complex addition/subtraction respectively, while the fMRI data were recorded by a Seimens 1.5 T MR machine. Block-design was used in the tasks. Two calculation tasks and one base-line tasks were performed for the block-design. Simple calculation task was single-digit addition and subtraction, while the complex was multi-digit addition and subtraction. The base-line task was to tell whether the two numbers were the same in every trial. Statistical parametric mapping (SPM99) was employed to process data and localize functional areas. We compared the average activation intensity of each activated brain regions in the same calculation task and the activation intensity of the same regions in both tasks respectively. Both the cortex and the subcortical structures including basal ganglia and thalamus were activated during simple and complex mental calculations. Similar brain regions in subjects including frontal lobe, parietal lobe, occipital lobe, cingulate gyrus, thalamus and cerebellum were engaged in simple and complex addition/subtraction. In the same task, activation intensity of all activated brain areas differed insignificantly. Compared with the complex task, the right parietal lobe was not activated in the simple one. The subcortical structures such as the caudate nucleus and the left marginal division of the striatum (MrD) were activated in both two calculation tasks. The cortical regions involved in both simple and complex addition/subtraction were similar. In conclusion, both the cortex and the subcortical structures were activated during the mental calculation. The cortex including the frontal cortex, parietal cortex, and cingulate gyrus were activated during mental calculation, while the subcortical structures such as the caudate nucleus, the globus pallidum and the left marginal division of the striatum also played a critical role in the neural networks of the calculation at the same time. Right parietal lobe (supramarginal gyrus) was engaged only in the complex task, which suggested that this region might be involved in the visuospatial memory and processing.

New learning and memory related pathways among the hippocampus, the amygdala and the ventromedial region of the striatum in rats.

BACKGROUND: The hippocampus, central amygdaloid nucleus and the ventromedial region (marginal division) of the striatum have been reported to be involved in the mechanism of learning and memory. This study aimed elucidating anatomical and functional connections among these brain areas during learning and memory. RESULTS: In the first part of this study, the c-Fos protein was used to explore functional connections among these structures. Chemical stimulation of either hippocampus or central amygdaloid nucleus results in dense expression of c-Fos protein in nuclei of neurons in the marginal division of the striatum, indicating that the hippocampus and the central amygdaloid nucleus might be functionally connected with the marginal division. In the second part of the study, the cholera toxin subunit B-horseradish peroxidase was injected into the central amygdaloid nucleus to observe anatomical connections among them. The retrogradely transported conjugated horseradish peroxidase was observed in neurons of both the marginal division and dorsal part of the hippocampus following the injection. Hence, neural fibers from both the marginal division and the hippocampus directly projected to the central amygdaloid nucleus. CONCLUSION: The results implicated potential new functional and structural pathways through these brain areas during the process of learning and memory. The pathways ran from ventromedial portion (the marginal division) of the striatum to the central amygdaloid nucleus and then to the hippocampus before going back to the marginal division of the striatum. Two smaller circuits were between the marginal division and the central amygdaloid nucleus, and between the central amygdaloid nucleus and the hippocampus. These connections have added new dimensions of neural networks of learning and memory, and might be involved in the pathogenesis of dementia and Alzheimer disease.

Expression of c-fos and c-jun proteins in the marginal division of the rat striatum during learning and memory training.

BACKGROUND: A new brain region, the marginal division (MrD), was discovered at the caudal margin of the neostriatum. The MrD was shown to be involved in learning and memory in the rat. The aim of this study was to investigate the expression of the immediate-early genes c-fos and c-jun in the MrD of the striatum during learning and memory processes in the rat, immunocytochemical and Western blot methods were used to examine Y-maze trained rats. METHODS: The rats were divided into three groups, namely the training, pseudotraining, and control groups. After Y-maze training, the expression of the immediate-early genes c-fos and c-jun in the MrD of the rats was investigated using immunocytochemical and Western blot methods. RESULTS: After one hour of Y-maze training, the expression of c-jun and c-fos proteins was significantly enhanced in the MrD; the c-jun protein, in particular, was more intensely expressed in this region than in other parts of the striatum. The expression of these two proteins in the training group was significantly higher than in the pseudotraining and control groups. In addition, positive expression was also found in the hippocampus, cingulum cortex, thalamus, and in other areas. Western blot disclosed two immunoreactive bands for the anti-c-fos antibody (47 kD and 54 kD) and two immunoreactive bands for the anti-c-jun antibody (39 kD and 54 kD). CONCLUSIONS: These results indicate that the immediate-early genes c-fos and c-jun participate in signal transduction during the learning and memory processes associated with Y-maze training in rats.

The marginal division of the striatum and hippocampus has different role and mechanism in learning and memory.

The memory function of the hippocampal formation (Hip) and the marginal division (MrD) of neostriatum was compared. Rats with bilateral lesions of the MrD either immediate or 24 h after training in Y-maze were found to have decrease in correct runs in both groups. However, animals with transected afferent and efferent nerve bundles to isolate the Hip immediately or 24 h after training in Y-maze were found to show a decrease in correct runs only in the group injured immediately after Y-maze training but not in the 24 h group suggesting that MrD is likely involved in the entire process of long-term memory consolidation whereas the Hip only contributes to memory in the early stage. In addition, animals treated with a NMDA receptor (NMDAR) blocker, e.g. MK-801, showed decreased correct runs in Y-maze test and in expression level of phosphorylated CREB (pCREB) in neurons of the MrD but not in the Hip. Furthermore, animals treated with okadaic acid (OA), a potent protein phosphatase 1 inhibitor, showed increased correct runs in the Y-maze test. The expression level of pCREB and c-Fos and c-Jun was found increased in neurons of the MrD and the Hip in response to OA treatment. In conclusion, NMDAR and pCREB are involved in memory functions of both the Hip and the MrD. NMDAR might regulate pCREB level in neurons of the MrD but not in the Hip. Hence, the processes and mechanism of learning and memory involved in the MrD and the Hip may be different.

[Research progress in the structure and functions of the marginal division in the striatum].

In the year 1987, we discovered a new area in the striatum that was subsequently designated as the marginal division according to the location where it situates. More than 10 years of systemic study has yielded substantial knowledge of the unique structure of this new region, and it has come to light that the marginal division is predominantly associated with learning and memory functions, as have been recognized by researchers either nation-wide or world-wide. Further study of the marginal division may have potential significance in efforts to promote human intelligence and in contriving means for prevention of Alzheimer's disease.

Differential display analysis of gene expression in the hippocampus, marginal division and other related brain areas: a preliminary study.

OBJECTIVE: To investigate the difference in the expression profiles in the hippocampus, marginal division and other related brain areas for identification of genes specific to the hippocampus and marginal division. METHODS: Fetal hippocampus, marginal division, caudate putamen and amygdala were obtained and mRNA differential display technique was employed to study the gene expression in the 4 brain areas. RESULTS: Two differentially expressed fragments were isolated from each of the hippocampus and marginal division, and cloning and sequence analysis of one of the fragment 277 bp in length from the hippocampus showed total homology with the sequence of human clone AC0049. CONCLUSION: The 4 brain areas have different gene expression profiles.

[Functional connection between the marginal division and hippocampus in rats].

OBJECTIVE: To investigate the functional connection between the marginal division of the striatum and hippocampus, a brain region that play a vital role in learning and memory. METHODS: Morphological localization of functional activity of the nervous system was employed. Kainic acid (0.01%) was stereotaxically injected into the hippocampus as a chemical stimulus, and immunohistochemistry method was used to show the expression of c-Fos in rat brain. RESULTS: c-Fos was intensely expressed in the hippocampus, amygdaloid nucleus, the bed nucleus of the stria terminals and cerebral cortex; in the striatum, a stretch in the marginal division where c-Fos-positive nuclei congregated was observed, while c-Fos expression was scarcely detectable in the caudate putamen and globus pallidus. CONCLUSION: Functional connection exists between the marginal division and hippocampus in rats.

[Expression of gamma-amino butyric acid and its receptor in the marginal division of rat striatum].

OBJECTIVE: To investigate the expression of the inhibitory amino acid gamma-aminobutyric acid (GABA) and its receptor GABAR (B1) mRNA in the marginal division of rat striatum. METHODS: The expression of GABA and its receptor GABAR (B1) mRNA was studied by way of immunocytochemistry and molecular in situ hybridization method. RESULTS: Dense GABA-positive immunoreactive fibers and a few positive cells were found in the marginal division of the rat striatum, along with glutamic acid decarboxylase (GAD)-positive fibers and cell bodies. GABA- and GAD-positive cells and fibers were also seen in the cerebral cortex and hippocampus. Numerous cells positive of the expression of GABAR (B1) receptors mRNA were observed in the marginal division whereas only a few positive cells were found in the caudate putamen. GABAR (B1) receptor mRNA expression was also observed in some cells in the cerebral cortex and hippocampus. CONCLUSION: The expression of GABA and its receptor in the marginal division of rat striatum indicates a regulatory mechanism of the marginal division of the striatum by GABA, suggesting that GABA can affect the learning and memory function of the marginal division through inhibiting the neurotransmitter release in the presynaptic terminal or modulating the other neurotransmitters.

[Distribution of substance P and its receptor in the marginal division of rat striatum and its association with the function of learning and memory].

OBJECTIVE: To investigate the distribution of the substance P (SP) and its receptor in the marginal division (MrD) of rat striatum and to understand the relationship between SP and the learning and memory function of rats. METHODS: Using immunohistochemistry and in situ hybridization techniques, the distribution of SP and its receptor in the MrD was studied, and the relationship between the SP and learning and memory of the MrD was observed by means of SP receptor gene knockout in combination with Y-maze test. RESULTS: Numerous SP immunopositive fibers and large quantities of SP receptor protein and NK1 mRNA were identified in the MrD of rat striatum. After knockout of the SP receptor gene in the MrD, the ability of learning and memory of the rats was obviously decreased. CONCLUSION: SP and its receptor in the MrD may play important roles in the learning and memory function of rat, possibly through the regulation of the neurotransmitters as 5-HT by SP via NK1 receptor.

[Effects of kainic acid that damages the marginal division of rat striatum on hippocampal long-term potentiation].

OBJECTIVE: To investigate the relationship between the marginal division (MrD) of the striatum and other brain regions associated with learning and memory. METHODS: Long-term potentiation (LTP) was induced by high-frequency stimulation of the perforant path-dentate gyrus, and changes in hippocampal LTP after destruction of the marginal division with kainic acid were observed. RESULTS: High-frequency stimulation of the perforant path produced significant increases in the peak amplitudes of the population spike (PS) in normal rats and those receiving saline treatment. In rats with damaged MrD, the increase in PS and the excitatory postsynaptic potential were less obvious compared with normal or saline-treated rats, indicating that the LTP of the hippocampus was attenuated by damage of the MrD. CONCLUSION: Damage of the MrD impacts the LTP formation in the hippocampus.

[Expression of immediate-early genes c-fos and c-jun in the marginal division of striatum during learning and memory].

OBJECTIVE: To study the expression of immediate-early genes c-fos and c-jun in the marginal division (MrD) of rat striatum during learning and memory. METHODS: After Y-maze training in rats, the expression of immediate-early genes c-fos and c-jun in the MrD was investigated immunocytochemically. RESULTS: After 1 h of Y- maze training, the expression of c-Fos and c-Jun proteins was significantly enhanced in the MrD, where c-Jun protein in particular was more intensely expressed than in other parts of the striatum. The training group showed significantly higher expressions of the 2 proteins than pseudotraining group (P<0.01). In addition, positive expression was also observed in the hippocampus, cingulum cortex and other parts of the brain. CONCLUSION: Immediate-early genes c-fos and c-jun in the MrD participate in the signal transduction during learning and memory processes in the courses of Y-maze training of the rats.