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Objective To investigate the neural representations of long-term digital memory in human brain by functional magnetic resonance imaging (fMRI) technique. Methods 22 right-handed normal volunteers were recruited to participate in a test of long-term digital memory while the fMRI data were recorded. Control tasks were performed for the block-design. SPM 99 was used to analyze the data and to obtain the activated brain regions.Numbers of activated voxels were used to calculate lateralization index (LI). Results When the threshold was set as P＜0. 0001 ,using a one-sample t -test,the middle gyrus of the left frontal lobe(t=9.68) and the right cerebellum ( t = 9.85 ) were activated remarkably during the memory task. The subcortical structures including the thalamus (t=6.72) and the caudate (t=6.58) were also obviously activated during the memory task. LI of the numbers of activated voxels was 0.51. Conclusions The subcortical structures and the cerebellum as well as the cerebral cortex are collaborative to contribute to long-term digital memory function in human brain. The results also reveal that the functional areas of long-term digital memory in human brain are localized with the functional lateralization in the left hemisphere.
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Objective To examine whether the marginal division of the striatum(MrD)is involved in the associative learning and memory function of human brain with the help of functional magnetic resonance imaging(fMRI)technique.Methods Sixteen right-handed normal volunteers participated in a test of paired-word associative learning and memory,while the fMRI data were recorded.Control tasks were performed for the block-design.Statistcs parameter mapping 99 was used to analyze the data and to obtain the activated brain regions.Results When the threshold was set as P＜0.005.using a one-sample T-test,the left occipital lobe and the superior and middle gyrus of the left frontal lobe were activated remarkably during the encoding process of the paired-word associative learning and memory task,with the maximum intensity T value being 13.87 and 9.36.respectively.The left MrD was also obviously activated during this stage(T value was 5.46).But during the retrieval process,the left parietal lobe was prominently activated(T value was 8.73).Conclusion The resuhs of this study reveal that the subcortical structures such as MrD as well as the cerebral cortex are involved in the associative learning and memory of paired-word in human brain.
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BACKGROUND: The marginal division, a new sub-region in rat brain striatum discovered in recent decades, has been found to closely relate to learning and memory function of the brain. The immediate-early genes such as c-fos and c-jun participate in the signal transduction of learning and memory in the marginal division. But what other intermediate events are initiated in the marginal division in the process of learning and memory?Cyclic adenosine monophosphate (cAMP) response element-binding protein (CREBP) is an molecule essential for the formation of long-term memory,and investigation of the expression and distribution of phosphorylated CREBP in the striatum may help understand the signal transduction mechanism in the striatum during learning and memory at the molecular level.OBJECTIVE: To investigate the expression of phosphorylated CREBP in rat brain stratum during learning and memory process.DESIGN: Completely randomized controlled study.SETTING: Institute of Neurosciences, Zhujiang Hospital of the First Military Medical University of Chinese PLA.MATERIALS: This experiment was conducted in the Institute of Neurosciences, Zhujiang Hospital of the First Military Medical University of Chinese PLA between April and August 2003. Totally 48 normal male adult SD rats were provided from the Experimental Animal Center of First Military Medical University, and after two Y-maze tests, 40 rats were selected for this study (MG-2 type, Sanshengxing electricity company).METHODS: The 40 SD rats were randomized into 4 equal groups. The rats in the first group were subjected to training to acquire dark avoidance reflex in a Y maze, those in the second group underwent sham training with only light stimulation in the Y maze without electricity on the floor.The rats in the third group were trained in the Y maze with electricity on the floor but not light stimulations, with the rest 10 rats serving as the control group subjected to sham training in the Y maze without either electric or light stimulations. After the training in the Y maze, the rats were sacrificed immunohistochemical detection of phosphorylated CREBP expression in the brain striatum.MAIN OUTCOME MEASURES: Expression of phosphorylated CREBPin rat brain striatum.RESULTS: All the 40 rats enrolled in this study were examined for phosphorylated CREBP expression. Positive expression of phosphorylated CREBP was observed in the medial marginal division of the brain striatum after the rats were trained in the Y maze with electric stimulation, but no obvious expression was seen in rats in the sham training or control groups.Massive expression of phosphorylated CREBP could be observed, typically,in the hippocampus, front prefrontal lobe cortex and cingulate gyrus of the rat brain.CONCLUSION: The transcriptional factor phosphorylated CREBP in the marginal division of the striatum participates in the signal transduction for learning and memory in rats receiving Y maze training to acquire dark avoidance reflex.
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BACKGROUND: Hippocampal structure in brain is the division related to learning and memory, generally it is closely relevant to spatial cognitive activity. Marginal division of striatum is a latest discovered subdivision related to learning and memory function of brain, whether is its learning and memory function different from that in hippocampus?OBJECTIVE: To compare the difference, function and importance in learning and memory function between marginal division of striatum and hippocampus in brain and observe the difference in escape learning and memory between marginal division of striatum and hippocampus.DESIGN: Completely randomized controlled experiment.SETTING: Institute of Neuroscience in Zhujiang Hospital Affiliated to First Military Medical University of Chinese PLA.MATERIALS: The experiment was performed in Institute of Neuroscience in Zhujiang Hospital Affiliated to First Military Medical University of Chinese PLA from March 2002 to July 2003. Totally 109 normal male adult SD rats were employed and 75 rats of them were screened as the qualified animals by twice Y-maze test. Randomly, 25 rats were divided into damaged marginal division of striatum group (DMD group), 10 rats were into bilateral fimbria-fornix transection group (FFT group), 30 rats were into the control of marginal division of striatum (MD control) and 10 rats were into the control of bilateral fimbria-fornix group (FF control). After 24 hours training in Y-maze,In DMD group, 10 g/L kainic acid 0.1 to 0.2 μL was used to damage bilateral marginal division of striatum of rats. In MD control, physiological saline of minim dose was injected in bilateral marginal division of striatum of rats. In FFT group, bilateral fimbria-fornix was transectioned. In FF control, the cortical tissue of the superficial layer of bilateral fimbria-fornix was transectioned. The operation was done on the second day after the 2nd screening. The behavior of rats in learning and memory was observed in Y-maze on the 5th day after operation (during 30 times of maze test, if success frequency ≥ 15,normal capacity of learning and memory was identified.).MAIN OUTCOME MEASURES: Success frequency of rats in different groups in Y-maze learning before and after operation.RESULTS: Of 109 normal male adult SD rats, 75 rats were screened to be qualified after twice Y-maze test. During the experiment, 3 rats were died and other 32 rats fell into disuse for the drug or physiological saline was not injected accurately to the marginal division of striatum. Terminally, 40 rats entered the analysis in total, of which, 11 rats were in DMD group, 9 rats in MD quency in Y-maze learning of rats in DMD group after operation was lower than MD control, FFT group and FF control [(9.27±4.29) times, (22.56±4.25)frequency in Y-maze learning of rats in DMD group after operation was also significantly lower than that before operation [(9.27±4.29) time, (18.27±3.07)FFT group was basically same as FF control and MD control (P=0.660 and P=0.489) and it was basically same to the success frequency in Y-maze learning before operation (P=0.700).CONCLUSION: The learning of Y-maze in rats with damaged marginal division of striatum was remarkably reduced and there was no obvious change in learning and memory between the rats with fimbria-fornix transaction and without transaction. It is verified that marginal division of striatum can reflex complex learning and memory behavior in electric Y-maze test, which cannot be achieved in hippocampus. It is further explained the difference of the two divisions in controlling learning and memory in cerebrum, the marginal division of striatum is able to control hippocampus in learning and memory function.
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Using immunohistochemical method, the distribution of eight kinds of peptidergic neurons, i. e. cholecystokinin(CCK),vasoactive intestinal polypeptide (VIP), substance P(SP), neurotensin (NT), galanin (GAL), calcitonin gene-related peptide (CGRP), corticotropin-releasing factor(CRF) and thyrotropin-releasing hormone(TRH), of the thalamus in the rat was investigated. Immunoreactive cell bodies and fiber terminals were mainly located in the midline nuclei, intralaminar nuclei, habenular nucleus and posterior nuclei of the thalamus, but a few of positive structures in the anterior nuclei, ventral nuclei and reticular nucleus were also found. The distribution of different peptidergic neurons in the thalamus was different from each other. A large quantity of SP-, NT- and GAL- like cell bodies and all of above-mentioned eight peptidergic fiber terminals were observed in the midline nuclei and intralaminar nuclei. More CCK and CGRP positive cell bodies were seen in the posterior nuclei. Some VIP, SP, NT, GAL and CRF positive cell bodies and all kinds of the positive terminals, except CGRP, were found in the habenular nucleus. The immunoreactive structures which were found in present study, particularly the distribution of positive terminals, were more widely than those were reported. The distribution of some CCK, VIP, NT, GAL, CGRP and TRH positive cell bodies and terminals in the thalamus have not been reported previously.
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The afferent projections of the prefrontal cortex(PFC) from the cerebral cortex were studied using WGA-HRP technique in 25 rats. The PFC of the rat re- cieved the afferent projections widely arising from the frontal, parietal,temporal, occipital, cingulate, piriform and retrohippocampal cortex. Furthermore,the dif- ferent organizations of the cortical afferent projections of the medial and lateral part of the PFC were also found. Besides the afferents from the somatic and visceral sensory cortex, the PFC of rat also recives afferents of visual and auditory cortex and it appears to be a multiple sensory convergence area.
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WGA-HRP was iontophoretically delivered into the habenular nuclei in 40 rats to observe the distribution of the retrograde labeled cells; and into the entopeduncular nucleus(EPN), lateral preoptic area(LPO), medial preoptic area(MPO), nucleus septalis fimbriatis(SF), nucleus triangularis septi(TS), nucleus tractus diagonalis (Broca)(DBN)and lateral hypothalamic area(LHA) in 12 rats to observe the distribution of the orthograde labeled fibers in the habenular nuclei. It was found that the afferents of various parts of the habenular nuclei were different.The lateral habenular nucleus mainly recieves the afferents from the EPN, LPO and LHA, and the medial habenular nucleus from the SF, TS and LHA. Furthermore, the lateral habenular nucleus can be divided into medial and lateral parts, the medial habenular nucleus can be divided into medial and lateral parts as well, their afferent connections are also different.
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The divergent axon collaterals from neurons in locus coeruleus have been in vestigated by means of fluorescent double labeling technique in 36 rats.Different fluorescent tracers, Fast Blue, Nuclear Yellow, Propidium iodide, Bisbenzimide, Evans Blue, DAPI and Primuline were injected into the prefrontal cortex, the thalamus, the hippocampus, the cerebellum and cervical cord to observe the double retrograde labeling neurons of the locus coeruleus.Following unilateral or bilateral combined injections of two fluorescent tracers into the thalamus and cerebellum, the hippocampus and cerebellum, the hippocampus and thalamus, the larefrontal cortex and cerebellum, the prefrontal cortex and thalamus, the prefrontal cortex and cervical cord, the hippocampus and cervical cord, the cerebellum and cervical cord, double labeled cells were found in locus coeruleus, and some topographical organizations were also found.
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The afferent projections of the locus coeruleus (LC) were studied in 32 rats following the microelectrophoretic delivery of HRP into the different parts of the LC. It was revealed that the LC received afferent fibers widely from the brain, and some topographic localization may exist. Following the injection of HRP into the rostral part of the LC, HRP labeled neurons were observed widely distributed in the brain and spinal cord. In the telencephalon, moderately HRP labeled neurons were observed in the bed nucleus of the stria terminalis, medial and lateral preoptic area, and a few HRP labeled neurons were observed in the areas 13 and 14 of the insular cortex, areas 8 and 10 of the frontal cortex and the central amygdaloid nucleus. In the diencephalon, numerous labeled neurons were observed in the lateral and dorsal hypothalamic area, and a few labeled neurons were observed in the paraventricular nucleus, ventromedial nucleus and arcuate nucleus of the hypothalamus, the parafascicular nucleus of the thalamus, zona incerta and the lateral habenular nucleus. In the brain stem, cerebellum and spinal cord, numerous labeled neurons were observed in the periventricular gray substances, reticular formation and Vestibular nuclei, and a few labeled neurons were observed in the lateral reticular nucleus, solitary nucleus, prepositus nucleus, nucleus of the Spinal tract of the trigeminal nerve, nucleus raphe magnus, nucleus raphe pontis, nucleus raphe dorsalis, parabrachial nucleus, substantia nigra, nucleus lemnisci lateralis, fastigial nucleus, and spinal cord. However, following the injection of HRP into the caudal part of the LC, labeled neurons were observed only in the brain stem, cerebellum and spinal cord, no HRP labeled neurons were found in the telencephalon and diencephalon.
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PAP and ABC methods have been used to detect the Oxytocin-like (OXT-L) neurons in the hypothalamus of the rat and the results obtained were compared with the CT-HRP retrograde tracing study from the posterior pituitary to the hypothalamus by Ju et al. It was verified that the projections to the posterior pituitary came from the supraoptic nucleus, paraventricular nucleus, anterior and posterior fornical nucleus, perivascular cell groups, preoptic and anterior hypothalamic areas, the dorsal accessory cell groups, and the periventricular area, especially forming subependymal plexuses along the lateral wall of the third ventricle and beneath the interventricular foramen. By combining WGA-HRP retrograde tracing and immunohistochemistry methods, OXT-L neurons in all the above listed nuclei or cell groups were found to project to the posterior pituitary. The subependymal plexuses may serve as a link between the CSF in the ventricles and the posterior pituitary.
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WGA-HRP was injected into the dorsomedial nucleus of thalamus (DM)by means of microiontophoretical delivery in 19 rats, and into the dorsal division of anterior cingulate cortex (ACd), the prelimbic area (PL), the dorsal agranular insular area (AId) of prefrontal cortex by using microinjective system in 17 rats to observe the efferent projections of the DM.It was found that the DM projected to a large part of the prefrontal cortex including the medial precentral area (PCm), ACd, PL, AId, ventral agranular insular area (AIv), medial orbital area (MO), ventral orbital area (VO), ventrolateral orbital area (VLO), and some topographical organizations were also found. The lateral segment of DM projects to the ACd, PCm, PL, AId, AIv and VLO. The intermediate segment of DM projects to the AId and AIv. The medial segment of DM projects to the AId, PL, IL, AIv, MO and VO. Furthermore, the DM also projects to some subcortical nuclei, such as the reticular nucleus of thalamus (R), the lateral preoptic area (LPO), the lateral hypothalamic area (LHA), the caudoputamen, the nucleus accumbens and the parafascicular nucleus of thalamus. In addition, some reciprocal connections between the DM and the ACd, PCm, PL, IL, AId, R, LPO and LHA were observed.
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Using the HRP retrograde tracing method, the projections from the mammillary nucleus to the anterior nuclear complex of the thalamus were studied in the rat. The mamillo- thalamic projections arised from either the medial mammillary nucleus or the lateral mammillary nucleus. The efferent fibers of the lateral part of the medial mammillary nucleus projected mainly to the ipsilateral anteroventral nucleus of the thalamus. The efferent fibers from the medial part as well as the posterior part of the medial mammillary nucleus projected to the ipsilateral anteroventral and anteromedial nucleus of the thalamus. In addition, the projections from the median part of the medial mammillary nucleus to the anteromedial nucleus of the thalamus were also observed. The efferent fibers of the lateral mammillary nucleus projected bilaterally to the anterodorsal nucleus of the thalamus, but more on the ipsilateral side.
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WGA-HRP was injected into different segment of the dorsomedial nucleus (DM) of thalamus by means of microiontophoretical delivery in 19 rats to observe the afferent projections of DM. It is found that the DM received afferent projections widely from the frontal cortex, basal telecephalon, limbic system, monoaminergic neuron, reticular formation, central gray matter and superior colliculus. Furthermore, some topographical organization has also been observed. The medial segment of DM received afferent projections mainly from dorsal agranular insular cortex, infralimbic cortex, amygdaloid complex, septum, bed nucleus of the stria terminalis and raphe nuclei, related with the function of the limbic system. The central segment of DM received afferent projections from the dorsal agranular insular cortex and the prepiriform cortex, also related with the function of the limbic system. The lateral segment of DM received afferent projections mainly from the medial precentral cortex, dorsal division of anterior cingulate cortex, E-W nucleus and superior colliculus, related with the function of eye movement. In addition, all the three segments of DM received numerous afferents from the substantia innominata, nucleus tractus diagonalis (Broca), lateral preoptic area and reticular nucleus of the thalamus.
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0.02～0.3?l of 33％ HRP (Sigma Ⅵ) solution in sterile water were injected with a stereotaxic instrument into various sites of the caudate-putamen in 40 rats. The animals were perfused transaortically with 3％ paraformatdehyde and 1％ glutaradehyde in 0.1 M phosphate buffer solution (pH7.4). Frozen sections were dried in a container with P_2O_5 for 2～4 hours and examined for fluorescence in the nucleus nigra. After which, the sections were processed for HRP reaction according to Mesulam's method. A number of cells of substantia nigra were found to show both fluorescence and HRP-positive product, thus confirming the dopaminergic nature of the nigroneostiatum projection.Furthermore, the nigroneostriatum projection was found to be topographically organized, the ventro-medial part of compact zone of the substantia nigra projecting to the dorso-medial caudate-putamen, the dorso-medial part of compact zone to the ventral caudate-putamen, the ventro-middle of compact zone to 1be dorso-lateral and central caudate-putamen, the caudo-lateral part to the central caudate-putamen, the middle part of reticular zone to the lateral and central caudate-putamen, the lateral zone of substantia nigra to the caudal caudate-putamen. Some overlap existed.Strionigral fibers were also topographically organized, which terminated predominantly about the cells of reticular zone. These may form a feedback loop concerning with the modulation of the activity of the dopaminergic neurons in the substantia nigra.
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Aging changes of neurotensin-like (NT-L) and galanin-like (GAL-L) cell bodies and fiber terminals in the central amygdaloid nucleus between the young and old rats were studied by means of immunohistochemical and microspectrophotometric techniques. NT-L cell bodies were mainly located in the central part (CeLn) of, centrolateral amygdaloid nucleus, a few of NT-L neurons were also found in the centrolateral amygdaloid nucleus, capsular part (CeLc) and centromedial amygdaloid nucleus (CeM). NT-L fiber terminals were seen mainly in the CeLn and CeLc. GAL-L cell bodies were observed only in the CeM. A marked decrease of density of NT-L cell bodies and fiber terminals in the central amygdaloid nucleus was found in the old rats as compared with young animals. No significant age difference in number of GAL-L cell bodies was observed in the central amygdaloid nucleus, but the staining intensity of GAL-L cell bodies was reduced remarkably. The results show that there are apparent changes with aging of the NT-L and GAL-L neurons in the central amygdaloid nucleus of the rat. The significance of the changes remains to be studied further.
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Using the immunohistochemical method combined with tract tracing techniques, a new subdivision, the marginal division, was found in the striatum of the rat. In this subdivision, substance P, enkephaline and dynorphin B terminals were densely localized. The present study investigated the synaptic organization of the substance P-like immunoreactive nerve terminals in the marginal division. Four major types of substance P immunoreactive synapses were identified. Axodendritic and axospinous synapses were the most common ones. Compound synapses with more than two synaptic components were also observed. One axo-axonic synapse was present. Both symmetric and asymmetric substance P-like immunoreactive synapses were seen in the marginal division. The existence of asymmetric synapses, small postsynaptic dendrites and axo-axonic synapses, distinguished the substance P-like immunoreactive nerve terminals in the marginal division from those in the other part of the striatum. The characteristics and complexity of the synaptic organization suggested that the substance P-like immunoreactive nerve terminals in the marginal division probably orginate from a different source and have a different function, as compared to those in the rest part of striatum.
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WGA-HRP was iontophoretically delivered into various parts of the habenular nuclei (the lateral segment of the lateral habenular nucleus LHb-L, the medial segment of the lateral habenular nucleus LHb-M, and the medial habenular nucleus MHb) in 40 rats to study the route and distribution of the anterograde labeled fibers and terminals in the brain. The efferent projections of the habenular nuclei follow three routes, the rostral, contralateral and caudal pathways. Along the rostral pathway fibers leave the lateral habenular nucleus, follow the stria medullaris thalami rostrally, and distribute to the thalamic dorsomedial nucleus, paratenial nucleus and lateral preoptic area. Fibers from the contralateral pathway distribute to the opposite lateral habenular nucleus by way of the commissura habenularum Fibers in the caudal pathway originate mainly from the MHb and LHb-M, and distribute to the interpeduncular nucleus with a dorsoventral topographic localization. In addition some of the caudal efferent fibers run caudally and terminate in the raphe nuclei and reticular formation etc.
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The projections of the cerebellar nuclei to the spinal cord were studied in the rat following injections of HRP into the cervical, thoracic, lumbar and sacral cord. Numerous HRP-positive neurons were found in the fastigial nucleus (F) and the posterior interpositus nucleus (IP) on both sides, but more on the contralateral side. In the F labelled neurons were mainly distributed in the ventrolateral and medial part of the middle portion of the nucleus, and considerable amount of labelled cells were found in the bundles of the cerebellar corticovestibular fibers as well. In the IP labelled neurons were seen only in the medial part of the nucleus. In addition, a few labelled cells were also found in the dentate nucleus (D) bilaterally. The present study suggests that the neurons of the F, IP and D project their fibers to C_4, a few fibers may extend caudally to C_8.
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Leu-enkphalin-like(L-ENK-L)neurons of the hypothalamus and its adjacentarea of the rat were stained immunohistochemically.It has been found that besidesthe area previously reported in the literature L-ENK-L neurons are also present inSFO and the ependyma of the third ventricle.By combining WGA-HRP retrogradetracing and immunohistochemical method,L-ENK-L neurons in supraoptic nucleus,paraventricular nucleus,periventricular area and anterior fornical nucleus were foundto project to the posterior pituitary,in which some neurons squeeze in between theependymal cells.The subependymal neurons may serve as a link between the ven-tricle and the posterior pituitary.
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WGA-HRP was injected into the dorsal part of anterior cingulate area,prelim- bic area,and dorsal agranular insular area of the prefrontal cortex in 25 rats to observe the afferent connections from the diencephalon and subcortical telencephalon. The afferent projections from the diencephalon mainly originate from the dorsome- dial nucleus of the thalamus,and some topographic localization may exist.Further- more,the afferent projections to the prefrontal cortex arise from the thalamic intralaminar nuclei(centrolateral nucleus,paracentral nucleus,centromedial nucleus and parafascicular nucleus),the ventral thalamic nuclei(ventrolateral nucleus,ven- tromedial nucleus,ventroanterior nucleus and ventroposterior nucleus),the midline nuclei(rhomboid nucleus,reuniens nucleus,paratenial nucleus,and paraventricular nucleus of the thalamus),the anteromedial nucleus,the lateral habenular nucleus, the posterior nucleus of the thalamus,and the lateral nucleus of the thalamus.The numbers projecting to the prefrontal cortex were different in different thalamic nuclei.The afferent projections from the hypothalamus mainly originate from the lateral hypothalamic area,lateral preoptic area,caudal magnocellular nucleus,and supramamillary nucleus.A few of afferent projections from the posterior hypothala- mic area,dorsomedial and ventromedial nucleus of the hypothalamus and zona inserta were also observed.The afferent projections from the subcortical telence- phalon mainly originate from the globus pallidus,the diagonal band nucleus,the septal nuclei(medial septal nucleus,lateral septal nucleus,septofimbrial nucleus and nucleus triangularis septi),the amygdaloid nuclei(lateral amygdaloid nucleus,lateral and medial part of basal amygdaloid nucleus,medial amygdaloid nucleus and cortical amygdaloid nucleus)and the claustrum.