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1.
The dorsocentral striatum (DCS) is the major site of input from medial agranular cortex (AGm) and has been implicated as an associative striatal area that is part of a cortical-subcortical circuit involved in multimodal spatial functions involving directed attention. Anterograde axonal tracing was used to investigate the spatial organization of corticostriatal projections to DCS. Injections of biotinylated dextran amine were made into several cortical areas known to project to DCS based on retrograde tracing data. These included areas AGm, lateral agranular cortex (AGl), orbital cortex, posterior parietal cortex (PPC), and visual association cortex. We discovered a previously undescribed geometry whereby the projection from AGm is prominent within DCS and the main corticostriatal projections from areas other than AGm are situated around the periphery of DCS: visual association cortex dorsomedially, PPC dorsally, AGl laterally, and orbital cortex ventrally. Each of these cortical projections is also represented by less dense aggregates of terminal labeling within DCS, organized as focal patches and more diffuse labeling. Because these cortical areas are linked by corticocortical connections, the present findings indicate that interconnected cortical areas have convergent terminal fields in the region of DCS. These findings suggest that DCS is a central associative region of the dorsal striatum characterized by a high degree of corticostriatal convergence.  相似文献   

2.
Corticostriatal projections to the dorsocentral striatum (DCS) were investigated using retrograde fluorescent axonal tracing. The DCS is of interest because of its role in directed attention and recovery from multimodal hemispatial neglect following cortical lesions of medial agranular cortex (AGm), an association area that is its major source of cortical input. A key finding was that the multimodal posterior parietal cortex (PPC) also contributes substantial input to DCS. This is significant because PPC and AGm are linked by corticocortical connections and are both critical components of the circuitry involved in spatial processing and directed attention. Other cortical areas providing input to DCS include visual association areas, lateral agranular cortex and orbital cortex. These areas also have reciprocal connections with AGm and PPC. Less consistent labeling was seen in somatic sensorimotor areas FL, HL and Par 1. Thalamic afferents to DCS are prominent from the intralaminar, ventrolateral, mediodorsal, ventromedial, laterodorsal (LD) and lateral posterior (LP) nuclei. Collectively, these nuclei constitute the sources of thalamic input to cortical areas AGm and PPC. Nuclei LD and LP are only labeled with injections in dorsal DCS, the site of major input from PPC, and PPC receives its thalamic input from LD and LP. We conclude that DCS receives inputs from cortical and thalamic areas that are themselves linked by corticocortical and thalamocortical connections. These findings support the hypothesis that DCS is a key component of an associative network of cortical, striatal and thalamic regions involved in multimodal processing and directed attention.  相似文献   

3.
Medial agranular cortex (AGm) is a narrow, longitudinally oriented region known to have extensive corticortical connections. The rostral and caudal portions of AGm exhibit functional differences that may involve these connections. Therefore we have examined the rostrocaudal organization of the afferent cortical connections of AGm by using fluorescent tracers, to determine whether there are significant differences between rostral and caudal AGm. Mediolateral patterns have also been examined in order to compare the pattern of corticocortical connections of AGm to those of the laterally adjacent lateral agranular cortex (AGl) and medially adjacent anterior cingulate area (AC). In the rostrocaudal domain, there are notable patterns in the connections of AGm with somatic sensorimotor, visual, and retrosplenial cortex. Rostral AGm receives extensive afferents from the caudal part of somatic sensorimotor area Par I, whereas caudal AGm receives input largely from the hindlimb cortex (area HL). Middle portions of AGm show an intermediate condition, indicating a continuously changing pattern rather than the presence of sharp border zones. The whole of the second somatic sensorimotor area Par II projects to rostral AGm, whereas caudal AGm receives input only from the caudal portion of Par II. Visual cortex projections to AGm originate in areas Oc1, Oc2L and Oc2M. Connections of rostral AGm with visual cortex are noticeably less dense than those of mid and caudal AGm, and are focused in area Oc2L. The granular visual area Oc1 projects almost exclusively to mid and caudal AGm. Retrosplenial cortex has more extensive connections with caudal AGm than with rostral AGm, and the agranular and granular retrosplenial subregions are both involved. Other cortical connections of AGm show little or no apparent rostrocaudal topography. These include afferents from orbital, perirhinal, and entorhinal cortex, all of which are bilateral in origin. In the mediolateral dimension, AGm has more extensive corticocortical connections than either AGl or AC. Of these three neighboring areas, only AGm has connections with the somatic sensorimotor, visual, retrosplenial and orbital cortices. In keeping with its role as primary motor cortex, AGl is predominantly connected with area Par I of somatic sensorimotor cortex, specifically rostral Par I. AGl receives no input from visual or retrosplenial cortex. Anterior cingulate cortex has connections with visual area Oc2 and with retrosplenial cortex, but none with somatic sensorimotor cortex. Orbital cortex projections are sparse to AGl and do not appear to involve AC.(ABSTRACT TRUNCATED AT 400 WORDS)  相似文献   

4.
Tsumori T  Yokota S  Ono K  Yasui Y 《Neuroreport》2003,14(1):81-86
The present tract-tracing study in the rat indicated that neurons in the ventrolateral part of the parafascicular thalamic nucleus (PF), where nigral fibers from the dorsolateral part of the substantia nigra pars reticulata (SNr) terminated, sent their axons to the ventrolateral part of the striatum as well as to the rostrolateral part of the lateral agranular cortex (AGl). We further demonstrated that symmetrical synaptic contacts were made between these nigral axons and striatum- or AGl-projecting PF neurons. Since the dorsolateral part of the SNr, ventrolateral part of the striatum and rostrolateral part of the AGl are responsible regions for orofacial behaviors, the nigrothalamostriatal and nigrothalamo-cortical pathways via the ventrolateral part of the PF may play a role in the control of orofacial motor function.  相似文献   

5.
A number of previous studies have indicated that an environmental manipulation, 48 h of light deprivation (LD), produces virtually complete and permanent behavioral recovery of function from neglect induced by medial agranular cortex (AGm) lesions. LD-induced behavioral recovery from neglect is correlated with physiological changes in the dorsolateral striatum, an area that contains the projection zone of AGm efferents in the dorsocentral striatum (DCS). In this study, the behavioral effects of 48 h of LD on subjects with either unilateral DCS, AGm, or combined AGm/DCS lesions were investigated to examine whether the integrity of the DCS is crucial for behavioral recovery from neglect and whether LD will have a therapeutic effect on extinction deficits. Subjects were tested for extinction to bilateral simultaneous stimulation of the forepaws, and visual, auditory and tactile neglect. Forty-eight hours of LD failed to produce behavioral recovery from neglect in rats with DCS lesions, or a therapeutic affect on extinction deficits in any of the groups. The results of this study further support the crucial role of the DCS in recovery from neglect induced by AGm lesions and suggests that the DCS may be the crucial site for the mechanisms leading to LD-induced recovery. Further, the ineffectiveness of LD on extinction suggests that components of the neglect syndrome are dissociable and may require different therapeutic interventions.  相似文献   

6.
Cerebral cells of origin for the corticospinal (CST), corticopontine (CP), corticorubral (CR) and corticostriatal (CS) fibers in the rat were identified following the simultaneous retrograde transport of propidium iodide (PI), fast blue (FB), fluorogold (FG) and diamidino yellow (DY). PI was injected into the contralateral C4 spinal cord segment while FB, FG and DY were injected into the ipsilateral medial pontine nuclei, red nucleus and striatum, respectively. Labeled pyramidal neurons projecting corticospinal axons were contralateral to injection in lamina V and ranged in size from small to large. These CST neurons occupied two distinct cortical areas. The cortical neurons of origin for the corticopontine, corticorubral and corticostriatal fibers were ipsilateral to injections. Labeled neurons were localized in cortical lamina V for the corticopontine and corticorubral fibers while corticostriate neurons were located in laminae III, V and VI. The CP, CR and CS labeled cells occupied one large cortical area which topographically included parts of the medial (AGm) and lateral (AGl) agranular cortices and the primary (SI) somatosensory cortex. Considerable overlapping of the cortical neurons of origin for the four motor fiber systems was apparent. More than 98% of the labeled cells were single labeled while less than 2% were double labeled. No triple or quadruple labeled neurons were observed. Hence, morphological evidence is presented that cortical motor neurons project mainly individual, rather than collateral, axons to each of the four motor associated nuclei investigated in this study. However, only a few cortical neurons projected axons simultaneously to a maximum of two nuclei involved in the motor pathways.  相似文献   

7.
On the basis of studies using intracortical microstimulation, the existence of rostrocaudally separate two forelimb representation areas has been inferred in the motor cortex of rats. They are termed caudal and rostral forelimb areas (CFA and RFA). In this study, it was confirmed first that RFA and CFA are located in cytoarchitectonically distinct areas (medial and lateral parts of agranular cortex (AGm and AGl), respectively). In the second part of this study, the distribution of thalamic and cortical neurons projecting to RFA and CFA was quantitatively compared by injections of small and relatively constant amounts of retrograde fluorescent dyes (diamidino yellow and fast blue) into these areas. It was observed that (1) main inputs to RFA originated from AGl, namely CFA (2) CFA received dominant inputs from AGm including RFA and caudally adjacent granular cortex and (3) wider cortical areas and larger number of neurons projected to CFA than to RFA. As for the thalamocortical projections, both RFA and CFA received inputs from various thalamic nuclei, such as VL, VM, Po, PC, PF, CL, but cells projecting to RFA and CFA were differentially located in each nucleus. It was found that labeled cell number and/or density in VM, PC, CL, CM and MD after RFA injections were significantly larger than those after CFA injections. On the other hand, labeled cell number and/or density in VPL and VL were significantly higher after CFA injections than after RFA injections. In comparison with findings in primates, the results suggest that the cortical motor areas of rats may be specialized for different aspects of motor control.  相似文献   

8.
Tsumori T  Yokota S  Ono K  Yasui Y 《Brain research》2001,903(1-2):168-176
The organization of corticotectal projections from the medial agranular cortex (AGm), which has been considered to contain rat's frontal eye field, was examined using anterograde and retrograde tracing techniques. When biotinylated dextranamine (BDA) injections were made into the rostral part of the AGm, small numbers of BDA-labeled axons were found in the rostral two-thirds of the superior colliculus (SC) while some labeled axons were seen in the caudal one-third of the SC. These labeled axons were distributed mainly in the lateral part of the stratum griseum intermediale. On the other hand, after BDA injections into the caudal part of the AGm, moderate to dense plexuses of labeled axons were found in the rostral two-thirds of the SC while some labeled axons were seen in the caudal one-third of the SC. These labeled axons were distributed in the ventromedial and dorsolateral marginal zones of the stratum griseum intermediale as well as in the stratum griseum profundum. The corticotectal projections were largely uncrossed. After combined injections of BDA into the caudal part of the AGm on one side and cholera toxin B subunit (CTb) into the paramedian pontine reticular formation on the opposite side or into the interstitial nucleus of Cajal on the same side, the overlapping distributions of BDA-labeled axons and CTb-labeled neurons were found in the ventromedial marginal zone of the stratum griseum intermediale ipsilateral to the site of BDA injection. These results suggest that the caudal part of the AGm plays a more significant role in the oculomotor function than does the rostral part of the AGm.  相似文献   

9.
This study of the rostral part of medial agranular cortex (AGm) was undertaken with two principal aims in mind. First, to delineate the efferent connections of AGm and compare these with the pattern of afferents defined by us in a previous study. Second, to provide a firmer basis for anatomical and functional comparisons with cortical regions in monkeys. Autoradiographic, horseradish peroxidase, and fiber degeneration techniques were used. Rostral AGm has a variety of corticocortical connections--with lateral agranular motor cortex (AGl); visual, auditory, and somatic sensory regions; and limbic/paralimbic areas including orbital, insular, perirhinal, entorhinal, retrosplenial and presubicular fields. The projections to orbital, perirhinal and entorhinal cortices are bilateral. Thalamic projections of rostral AGm are concentrated in the ventral lateral, central lateral, paracentral, mediodorsal and ventromedial nuclei. Moderate terminal fields are consistently seen in the reticular, anteromedial, central medial, gelatinosus, parafascicular, and posterior nuclei. More caudal projections reach the central gray, superior colliculus and pontine gray. The efferents of the adjacent AGl were also examined. Although many of these overlapped those of rostral AGm, there were no efferents to visual or auditory cortex and limbic/paralimbic projections were reduced. Thalamic projections were more focused in the ventral lateral and posterior nuclei and there were no terminal fields in the central gray or superior colliculus. Based on its afferent and efferent connections, role in contralateral neglect, and the results of microstimulation studies, rostral AGm can be viewed as a multimodal association area with strong ties to the motor system. On these structural and functional grounds, rostral AGm bears certain striking resemblances to the frontal eye field, supplementary motor, and arcuate premotor areas of monkey cortex.  相似文献   

10.
This study's goal is to identify subcortical adaptations that may contribute to recovery of function following cortical injury. After unilateral aspiration of the medial agranular region of frontal cortex (AGm), rats demonstrate neglect of contralateral stimuli and recover within 3–4 weeks. Previous studies indicate that compensatory neural alterations involving dopamine (DA) occur following this cortical injury and that recovery from neglect produced by frontal injury is accompanied by normalization of glucose utilization within subcortical structures including the basal ganglia. The current study examined Zif and JunB, IEG protein products constitutively expressed in striatum, rendering it possible to investigate the effects of unilateral AGm ablation on striatal function during unstimulated as well as amphetamine-stimulated conditions. Five days after surgery, when contralateral neglect was still evident, the numbers of Zif-like or Jun-like immunoreactive (IR) nuclei in the ipsilateral striata of AGm-ablated rats were reduced. These lesion effects were similar for both constitutive and amphetamine-stimulated IEG expression and were restricted to the dorsolateral caudate-putamen, where excitatory input from AGm is most dense. In contrast, 3 or more weeks after AGm ablation, in rats demonstrating recovery, normal striatal Zif- and JunB-like immunoreactivity occurred. Thus, striatal zif/268 and junB expression is reduced 5 days after AGm injury in rats demonstrating neglect and normalized 3 or more weeks later in recovered rats. These findings indicate that adaptations involving the striatal medium spiny neuron, a site of convergence of cortical glutamatergic and nigral dopaminergic afferents, may contribute to behavioral recovery following neocortical injury. © 1996 Wiley-Liss, Inc.  相似文献   

11.
R L Reep  J V Corwin 《Brain research》1999,841(1-2):43-52
The rostral and caudal portions of rat medial agranular cortex (AGm) play different functional roles. To refine the anatomical framework for understanding these differences, axonal tracers were used to map the topography of the connections of AGm with the striatum and thalamus. The striatal projections follow mediolateral and rostrocaudal gradients that correspond to the locations of the neurons of origin within AGm. Projections from rostral AGm are widespread and dense rostrally, then coalesce into a circumscribed dorsocentral region at the level of the pre-commissural septal nuclei. Projections from mid and caudal AGm are less widespread and less dense, and are focused more caudally. Striatal projections from the adjacent anterior cingulate and lateral agranular areas overlap those of AGm but are concentrated more medially and laterally, respectively. Thalamic connections of AGm are organized so that more caudal portions of AGm have connections with progressively more lateral and caudal regions of the thalamus, and the full extent of AGm is connected with the ventrolateral (VL) nucleus. Rostral AGm is interconnected with the lateral portion of the mediodorsal nucleus (MD1), VL, and the central lateral (CL), paracentral (PC), central medial, rhomboid and ventromedial nuclei. Caudal AGm has robust connections with VL, the posterior, lateral posterior and lateral dorsal nuclei, but little or none with MD1, CL/PC and VM. These differences in the subcortical connections of rostral and caudal AGm parallel their known differences in corticocortical connections, and represent another basis for experimental explorations of the functional roles of these cortical territories.  相似文献   

12.
Functional recovery from cortical injury may result from subcortical compensatory processes. This study examined basal gangliar expression of the immediate early gene c-fos after unilateral medial agranular cortex (AGm) ablation. In the ipsilateral dorsal globus pallidus of rats demonstrating neglect of contralateral stimuli (sacrificed 5 days postinjury), the numbers of amphetamine-induced Fos-positive nuclei were reduced 37% compared to intact hemisphere values. These reductions were no longer apparent in recovered AGm-ablated rats (sacrificed 21 + days postinjury). These findings mirror in timing and direction the changes in Fos seen in dorsolateral striatum after AGm ablation.  相似文献   

13.
This study refines the characterization of the rat parietal cortical domain in terms of cyto‐ and chemoarchitecture as well as thalamic connectivity. We recognize three subdivisions of the posterior parietal cortex (PPC), which are architectonically distinct from the neighboring somatosensory and visual cortices. Furthermore, we show that the different parietal areas are differently connected with thalamic nuclei. The medial portion of PPC (mPPC) is connected primarily with the medial portion of the lateral posterior nucleus (LP), whereas the lateral portion (lPPC) connects with the posterior complex (Po). The more caudolateral part of PPC (PtP) also projects to Po but can be distinguished from lPPC based on architectonic criteria. The primary somatic and visual cortices, neighboring PPC, are preferentially connected with the primary ventral posterior and dorsolateral geniculate nuclei, respectively, and less with the associational Po and LP. Particularly the border between the secondary visual cortex and the PPC has been a matter of controversy, but here we show that, although PPC subareas are connected with Po and medial LP, the medial and lateral secondary visual cortices are connected with lateral LP and a portion of medial LP different from that connected with PPC. The resulting delineations and specifications of connectivity with thalamic nuclei together with upcoming studies of cortical connectivity will facilitate detailed studies on the role of the subdivisions of PPC in the rat as diverse, higher order associative cortical areas, comparable to those described in the primate.for J. Comp. Neurol. 524:3774–3809, 2016. © 2016 Wiley Periodicals, Inc.  相似文献   

14.
Previous studies have shown that systemic administration of apomorphine is effective in producing acute drug-induced recovery from neglect induced by unilateral medial agranular cortex (AGm) lesions. More recent studies have demonstrated that recovery from neglect may be due to plastic changes occurring in the dorsal central striatum (DCS). Further, lesions of the DCS produce neglect that does not respond to systemic administration of apomorphine, suggesting that this area may be crucial for the therapeutic effects of apomorphine. In the present study, the behavioral effects of apomorphine infused into the DCS of animals with AGm lesion-induced neglect were examined to determine whether the DCS is a site of drug action. An infusion of 0.375 micro g of apomorphine into the DCS, but not a lateral striatal control area, was effective in producing acute recovery from neglect. The results of this study support the crucial role of the DCS in recovery from neglect induced by unilateral AGm lesions and suggest that the DCS may be an important site of action for the therapeutic effects of apomorphine. Because dopamine agonist therapy has been shown to be effective in humans with neglect, the results of the current study may represent an important step in the development of future pharmacotherapies.  相似文献   

15.
The posterior parietal cortex (PPC) is a multifaceted region of cortex, contributing to several cognitive processes, including sensorimotor integration and spatial navigation. Although recent years have seen a considerable rise in the use of rodents, particularly mice, to investigate PPC and related networks, a coherent anatomical definition of PPC in the mouse is still lacking. To address this, we delineated the mouse PPC, using cyto‐ and chemoarchitectural markers from Nissl‐, parvalbumin‐and muscarinic acetylcholine receptor M2‐staining. Additionally, we performed bilateral triple anterograde tracer injections in primary visual cortex (V1) and prepared flattened tangential sections from one hemisphere and coronal sections from the other, allowing us to co‐register the cytoarchitectural features of PPC with V1 projections. This revealed that extrastriate area A was largely contained within lateral PPC, that medial PPC overlapped with the anterior portion of area AM, and that anterior RL overlapped partially with area PtP. Furthermore, triple anterograde tracer injections in PPC showed strong projections to associative thalamic nuclei as well as higher visual areas, orbitofrontal, cingulate and secondary motor cortices. Retrograde circuit mapping with rabies virus further showed that all cortical connections were reciprocal. These combined approaches provide a coherent definition of mouse PPC that incorporates laminar architecture, extrastriate projections, thalamic, and cortico–cortical connections.  相似文献   

16.
The subcortical projections of the hamster's visual cortex were determined by use of injections of tritiated proline and heat lesions placed in different cortical loci. The brains were processed for autoradiography and silver impregnation of degenerating axons. Striate cortex was shown to project ipsilaterally to the dorsocaudal region of the caudate nucleus, a dorsolateral area within the thalamic reticular nucleus (RT), a laterodorsal region of the nucleus lateralis anterior (LA), the rostral half of nucleus lateralis posterior (LP), the whole territory of the dorsal (dLGN) and ventral (vLGN) geniculate nuclei, the anterior (PA) and posterior (PP) pretectal nuclei, the superior colliculus (SC), and the precerebellar pontine nuclei. In addition, the medial visual area (18b) was shown to project to a medial band of LA and part of the caudal half of LP, while the adjoining parietal cortex was seen to terminate in a lateral part of the caudate, a ventral band of LA, and the ventral half of rostral LP. Segregation of different cortical inputs was clear in LA, LP, caudate, and pons. The projections to dLGN, vLGN, SC, LP, and PA were retinotopically organized. Clear evidence of some topography was found within RT, PP, and the pons, although a consisten map could not be derived from the data.  相似文献   

17.
The infralimbic cortex is a visceromotor area of the cortex. To define the thalamic afferents of this area, contrast them with those of the lateral agranular cortex, a somatic motor region, and assess the degree to which the thalamus might coordinate the activity of these cortical areas through axon collaterals, we conducted a retrograde fluorescent double labeling study using bisbenzimide and Fast Blue. Injections into infralimbic cortex resulted in labeling in the mediodorsal, intralaminar, and midline nuclei. Injections into lateral agranular cortex resulted in labeling in the ventrolateral, ventrobasal, ventromedial, and intralaminar nuclei. There was almost no overlap in the thalamic labeling following injections into these two cortical areas. The pattern of labeling following infralimbic injections is discussed in terms of the possible function of the midline thalamic nuclei as a relay for visceral sensory information. The labeling in mediodorsal nucleus following infralimbic cortex argues for including this area in the definition of rodent prefrontal cortex. In addition, the results suggest that the role of the thalamus in coordinating the activity of these cortical areas is minimal.  相似文献   

18.
This study examined interactions between the corticostriatal glutamatergic system and the nigrostriatal dopaminergic system via immunocytochemical examination of dopamine (DA) agonist induction of the striatal immediate early gene product Fos following cortical injury. After unilateral aspiration of the medial agranular cortex (AGm) region of prefrontal cortex, rats were tested for orientation to visual, tactile, and auditory stimuli. Fos immunoreactivity induced by d-amphetamine (5 mg/kg) or apomorphine (5 mg/kg) was quantified in dorsolateral and ventrolateral regions of caudate-putamen (CPu) in rats still demonstrating sensory neglect (5 days postsurgery) and in rats recovered from sensory neglect produced by AGm ablation (29+ days postsurgery). The pattern of immunoreactivity of rats still demonstrating neglect differed from that of unlesioned rats or recovered AGm-ablated rats. In rats demonstrating sensory neglect, d-amphetamine or apomorphine induction of Fos in the ipsilateral CPu was reduced by about 40% compared to the contralateral CPu or to comparable readings in unlesioned controls. These asymmetries were restricted to dorsolateral CPu, the region receiving the densest input from AGm. In contrast, recovered AGm-ablated rats had DA agonist-induced striatal Fos immunoreactivity that was symmetrical between the two hemispheres and comparable to control values. These findings indicate that adaptations involving the striatal medium spiny neuron, a site of convergence of cortical glutamatergic and nigral dopaminergic afferents, may contribute to recovery from behavioral deficits resulting from neocortical injury. © 1995 Wiley-Liss, Inc.  相似文献   

19.
Projections from the basolateral nucleus of the amygdala (BLA) to the frontal cortex and the striatum were studied by using Phaseolus vulgaris-leucoagglutinin (PHA-L) anterograde tracing technique in the rat. PHA-L injections into the rostral part of the BLA resulted in a dense labeling of fibers with boutons in the dorsal bank of the rhinal fissure and in the lateral and the medial agranular cortex. PHA-L injections into the caudal part of the BLA produced a dense labeling of fibers in the medial surface of the frontal cortex. In most of the cortical regions, labeled fibers were predominantly distributed in two bands: one in the deep part of layers I and II and the other, heavier band, in layers V and VI. PHA-L injections into the rostral BLA resulted in a dense labeling of fibers with boutons in the olfactory tubercle, the rostral and caudolateral portion of the nucleus accumbens, and a large region of the caudate-putamen. The labeled area of the caudate-putamen included the rostroventral area, the central area, and the area caudal to the anterior commissure and dorsal and lateral to the globus pallidus. PHA-L injections into the caudal BLA produced fiber labeling in the most rostromedial area of the caudate-putamen facing the lateral ventricle, the medial portion of the nucleus accumbens, and the lateral septum. In the rostroventral striatum, PHA-L-labeled fibers selectively innervated the matrix compartment that contains abundant somatostatin-immunoreactive fibers. Compartmental segregation was less clear in the caudodorsolateral caudate-putamen and in the nucleus accumbens. Electron microscopy revealed that PHA-L-labeled boutons in the striatum contained abundant, small, round vesicles. These boutons formed asymmetrical synapses with dendritic spines of striatal neurons.  相似文献   

20.
A number of previous studies have indicated that lesions of the medial agranular cortex (AGm) in rats induce multimodal neglect and extinction to bilateral simultaneous stimulation (extinction), the two major symptoms of the neglect syndrome in humans. A recent study demonstrated that lesions of dorsocentral striatum (DCS), the site of AGm projections to the striatum, produce multimodal neglect qualitatively similar to that found with AGm lesions. In the present study, the behavioral effects of unilateral DCS lesions were examined in more detail for the major manifestations of neglect: hemineglect, extinction, and allesthesia/allokinesia. Subjects were tested for extinction to bilateral simultaneous stimulation of the forepaws three times a week for 3 weeks. Neglect testing occurred twice weekly and the subjects were tested for the presence of neglect by rating the magnitude of orientation to visual, tactile, and auditory stimulation. The results indicated that DCS operates, while demonstrating severe neglect, failed to demonstrate extinction or allesthesia/allokinesia. These findings suggest that the neural mechanisms that underlie neglect and extinction are dissociable in this system. A better understanding of the neural mechanisms that underlie extinction is particularly important because humans that have recovered from neglect often continue to demonstrate the debilitating symptoms of extinction.  相似文献   

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