SEARCH · PubMed Health

Results for “cortex”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 937 records · Page 52Linked to original sources

PubMed1995

Organization of the somatosensory cortex of the star-nosed mole.

The nose of the star-nosed mole consists of a star-like array of 22 fleshy appendages that radiate from the nostrils and are moved about to explore the environment. The surface of each appendage, or ray, is densely packed with bulbous receptor organs (Eimer's organs) that are highly responsive to tactile stimulation. Here, we report that these rays have corresponding morphological specializations in somatosensory cortex. Using a stain for the metabolic enzyme, cytochrome oxidase (CO), to reveal subdivisions of cortex, we disclosed a complex pattern of CO-dense stripes or bands separated by sharp lines or septa of low CO staining. Multiunit microelectrode recordings of neural activity evoked by light tactile stimuli in somatosensory cortex of anesthetized moles allowed us to mark some of the bands and other CO-dark regions with small electrolytic lesions and later relate recording results to the CO pattern. The results suggest that the primary somatosensory cortex, S1, has an unusual ventrolateral location and orientation with representations of mouth, nose rays, facial vibrissae, forepaw, and trunk in a rostrocaudal sequence. Within this presumptive S1, the 11 rays of the contralateral nose are represented as a rostral-to-caudal cortical pinwheel of 11 stripes. Cortex ventral to the primary set of stripes contains a second rostrocaudal representation of the rays as a mirror image of the first. This second set of stripes may be part of the second somatosensory area, S2. A third pattern of CO stripes appears to merge partially with caudal stripes of the first two patterns, so that a full pattern of 11 stripes is not obvious. This representation may correspond to the ventral somatosensory area, VS, of other mammals. An extensive area of cortex separated from the nose by a large septum was responsive to stimulation of the forelimb. Auditory cortex is unusually caudal in this mole, and the presumptive primary visual area is relatively small. These specializations of somatosensory cortex in star-nosed moles may be more patent examples of the consequences of more general factors in brain development. The observations are consistent with the general rule that the terminations of sensory projections with discorrelated activity segregate.

Animals↗

PubMed2002

Motor cortex activation is related to force of squeezing.

Primate studies have demonstrated that motor cortex neurons show increased activity with increased force of movement. In humans, this relationship has received little study during a power grip such as squeezing, and has previously only been evaluated across a narrow range of forces. Functional MRI was performed in eight healthy subjects who alternated between rest and right hand squeezing at one of three force levels. During scanning, motor performances were recorded using a dynamometer. At each force level, activation volume was measured within left sensorimotor cortex, right sensorimotor cortex, and a midline supplementary motor area. In left sensorimotor cortex, % signal change was also assessed. The range of force generated across the three force levels varied from 4.9 N to 276 N. In left sensorimotor cortex, activation volume increased significantly with greater force. The % signal change also increased with greater force and correlated closely with activation volume. In supplementary motor area, activation volume increased significantly with increasing force, but with greater intersubject variability. In right sensorimotor cortex, a trend for larger activation volumes with greater force did not reach significance. The laterality index, an expression of the relative degree of contralateral vs. ipsilateral sensorimotor cortex activation, did not change across the three force levels. Increased force of squeezing is associated with increased contralateral sensorimotor cortex and supplementary motor area activation. This relationship was found across the full spectrum of forces that the human hand is capable of generating. Use of a valid, reliable method for assessing motor behavior during functional MRI may be important to clinical applications.

Adult↗

PubMed2003

The entorhinal cortex of the mouse: organization of the projection to the hippocampal formation.

The origin and the terminations of the projections from the entorhinal cortex to the hippocampal formation of the mouse (C57BL/6J strain) have been studied using anterogradely and retrogradely transported tracers. The entorhinal cortex is principally divided into two areas, the lateral entorhinal area (LEA) and the medial entorhinal area (MEA). LEA is the origin of the lateral perforant path that terminates in the outer one-third of the molecular layer of the dentate gyrus, and MEA is the origin of the medial perforant path that ends in the middle one-third of the molecular layer of the dentate gyrus. This projection is mostly to the ispsilateral dentate gyrus; only a few labeled axons and terminals are found in the contralateral dentate gyrus. The projection to the dentate gyrus originates predominantly from neurons in layer II of the entorhinal cortex. The entorhinal cortex also projects to CA3 and CA1 and to subiculum; in both CA3 and CA1, the terminals are present in stratum lacunosum-moleculare, whereas in the subiculum the terminals are in the outer part of the molecular layer. The projection from the entorhinal cortex to CA3, CA1, and subiculum is bilateral, and it originates predominantly from neurons in layer III, but a small number of neurons in the deeper layers of the entorhinal cortex contributes to this projection. The projection of entorhinal cortex to the hippocampus is topographically organized, neurons in the lateral part of both LEA and MEA project to the dorsal part (i.e., septal pole) of the hippocampus, whereas the projection to the ventral (i.e., temporal pole) hippocampus originates from neurons in medial parts of the entorhinal cortex.

Animals↗

PubMed1994

The intrinsic geometry of the cerebral cortex.

The mammalian cerebral cortex is a profoundly convoluted six-layered surface. The expansion of the cortex during evolution appears to be due to an increase in the number of functional units as opposed to an increase in the complexity of the units. Geometric similarity predicts that cortical area should increase in proportion to the 2/3 power of cortical volume. Allometric analysis has shown that in fact cortical area increases as a nearly linear function of cortical volume. This can be understood by appreciating that smaller brains tend to be smooth (lissencephalic) and larger brains fissured (gyrencephalic). This process of fissuration has reached its modern terrestrial limit in the human brain where the majority of the cortical surface is hidden within folds. The thickness of the cortex (2-3 mm) is small compared to its area (2000-2500 cm2) so the application of the techniques of differential geometry (the mathematics of idealized surfaces) is justified. Geometric properties of surfaces fall into two categories: intrinsic properties (which are invariant under folding of the surface, e.g. distances measured on the surface) and extrinsic properties (pure folding). The extrinsic geometry of the cortex determines the anatomical appearance of the cortex and the shape of the white matter. The intrinsic curvature of the cortex affects the relative position of functional areas and the spread of activity within the surface itself. A cortical surface has been reconstructed from cross-sections. Analysis of this surface has shown that the cortex has significant intrinsic curvature and hence it is wrong to regard it as merely a crumpled bag. The particular geometry observed is such that the surface is peculiarly "close together". Theoretical considerations and simulations suggest that the intrinsic geometry may have a significant effect on: the necessity of non-uniform growth in models of cortical development; the location of integrative areas; and the synchronization of neuronal firing. It is suggested that intrinsic descriptions of the cortex may prove more natural than extrinsic ones.

Anthropometry↗

PubMed1997

FMRI studies of the supplementary motor area and the premotor cortex.

Brain activation patterns associated with three motor tasks, differing in the mode of movement selection, were studied in seven right-handed subjects, using functional magnetic resonance imaging (fMRI). The tasks consisted of sequences of finger movements in which the next finger was selected (i) according to a fixed sequence (FIX), (ii) in response to an external sensory cue (RAND), or (iii) on the basis of free, internal selection (SELF). Periods of hand relaxation (REST) alternating with the tasks served as a control. Functional maps resulting from comparison of the motor tasks with REST reveal activation in primary sensorimotor cortex, medial and lateral premotor areas, cingulate cortex, and parietal cortex. The task activation level, defined as the percentage MR signal increase for each task relative to REST, and the differential activation, defined as the percentage MR signal increase for RAND and SELF relative to FIX, were calculated in each area. All areas showed a higher activation level for RAND and SELF than for FIX. A significant difference in activation level or differential activation between SELF and RAND was found in the posterior part of the superior frontal sulcus, in a part of the premotor cortex on the lateral brain surface, in the anterior cingulate motor cortex, and in the posterior part of the superior parietal cortex. The high-resolution and single-subject approach, provided by fMRI, allowed the distinguishing of multiple foci in medial frontal areas, premotor cortex, and parietal cortex, reflecting the functional heterogeneity of these areas suggested by previous studies.

Adult↗

PubMed1998

Lesions of the caudal area of rabbit medial prefrontal cortex impair trace eyeblink conditioning.

The dorsolateral prefrontal cortex of the primate is an area known to be important for memory. Since the discovery of a homologous area in subprimate mammals, the caudal medial prefrontal cortex, rabbits have become useful in the investigation of working memory. The subprimate prefrontal cortex is intimately interconnected with the hippocampus, which is also recognized for its role in learning and memory. In addition, the hippocampus and prefrontal cortex have been shown to be similarly involved in a variety of tasks. Therefore, we hypothesized that the caudal medial prefrontal cortex of the rabbit would be necessary for acquisition of the hippocampally dependent trace eyeblink conditioning task. A total of 16 young rabbits (Oryctolagus cuniculus) received bilateral aspiration lesions of the prefrontal cortex. Six of the lesioned subjects were unable to acquire the trace eyeblink conditioning task, but were unimpaired when tested subsequently in the hippocampally independent delay conditioning task. The lesions of these 6 subjects either were limited to or extended into the caudal medial prefrontal cortex. In the remaining 10 subjects, which were not impaired in trace conditioning, the lesions were limited to the rostral pole. Our results support our original hypothesis and provide further evidence of the involvement of the subprimate caudal medial prefrontal cortex in learning.

Animals↗

PubMed1990

Patterns of interhemispheric and striate-peristriate connections in visual cortex of the South American marsupial Marmosa elegans (mouse opossum).

We have analyzed the distributions of interhemispheric and striate-peristriate connections in the South American marsupial, Marmosa elegans (mouse opossum). Following multiple injections of horseradish peroxidase (HRP) into one hemisphere, we found that anterogradely labeled terminations and retrogradely labeled perikarya are distributed unevenly in the contralateral hemisphere, forming a distinct tangential pattern in striate and peristriate cortex. This pattern delineates as many as eight peristriate areas relatively poor in commissural connections in lateral peristriate cortex, and in lateral and anterolateral portions of peristriate cortex. Single injections of HRP conjugated with wheat germ agglutinin into anterior or posterior regions of striate cortex produced as many as nine discrete ipsilateral fields of labeled perikarya, and terminations distributed over a broad cortical area in lateral and anterolateral peristriate cortex. Our observations of multiple areas with little or no HRP labeling in the interhemispheric pattern, and of multiple ipsilateral striate projection fields, indicate that the topography of visual cortex in Marmosa is highly elaborate, and suggest that extrastriate cortex is subdivided into several visual areas. Furthermore, by showing that the organization of visual cortex in this marsupial is as complex as in many placental mammals, our data support the view that a basic cortical plan, consisting of multiple visual areas, appeared early in mammalian evolution.

Animals↗

PubMed1996

Calcium-binding protein regucalcin mRNA expression in the kidney cortex is suppressed by saline ingestion in rats.

The effect of adrenalectomy (ADX) or saline ingestion, which is a hypertensive factor, on the expression of calcium-binding protein regucalcin mRNA in the kidney cortex of rats was investigated. The change of regucalcin mRNA levels was analyzed by Northern blotting using rat liver regucalcin complementary DNA (0.9 kb of open-reading frame). Regucalcin mRNA was expressed in the kidney cortex but not the medulla. Rats were adrenalectomized, and 48 h later they were sacrificed. ADX caused a reduction of regucalcin mRNA levels in the kidney cortex, suggesting that adrenal glands participate in the regulation of the mRNA expression. This reduction was not restored by the subcutaneous administration of dexamethasone with an effective dose (1 mg/kg body weight), which can stimulate kidney regucalcin mRNA expression. Regucalcin mRNA levels in the kidney cortex of rats were markedly suppressed by the ingestion of saline for 7 days. The ADX-induced decrease of renal cortex regucalcin mRNA levels was not appreciably restored by saline ingestion. Moreover, regucalcin mRNA levels in the kidney cortex of spontaneous hypertensive rats (SHR) were clearly decreased as compared with that of control (Wistar-Kyoto) rats. Meanwhile, calcium content in the kidney cortex was not significantly decreased by ADX or saline ingestion. The present study suggests that the expression of regucalcin mRNA in the kidney cortex of rats is suppressed by saline administration.

Adrenalectomy↗

PubMed1992

Neurofilament and glial alterations in the cerebral cortex in amyotrophic lateral sclerosis.

According to the literature, only minor nonspecific histopathological lesions are present in the motor cortex in up to 90% of the amyotrophic lateral sclerosis (ALS) patients. These observations, however, have so far been based mainly on conventional staining techniques. An exception to this is the focal glial reaction that has been reported following immunocytochemical staining for glial fibrillary protein (GFAP), which is reported to be distinctive for ALS in the cortex. Since perikarya of degenerating motor neurons in the spinal cord of ALS patients have been found to accumulate phosphorylated neurofilaments (PNF), an investigation was conducted to determine whether PNF was also a sensitive marker for alterations in the motor cortex in this condition. On large brain sections from 15 ALS patients, intense PNF immunoreactivity was found in the motor cortex from 11 patients. It was mainly localized in small pyramidal cells and basket cells, whereas only slight staining was observed in Betz cells. PNF-positive basket cells were also present in controls, but the basket cells staining for PNF were less numerous in controls than in ALS specimens. PNF-positive Betz cells were found in 47% of 15 ALS patients and in 10% of the controls. PNF accumulation was also found in swollen, probably degenerating, terminal boutons around perikarya of large pyramidal cells and Betz cells in the motor areas of ALS patients only. These observations suggest that the premotor innervation of the motor system is preferentially affected in ALS. Small brain sections, comprising the motor cortex, from 18 additional ALS patients demonstrated a similar PNF-staining pattern. However, differentiating ALS patients from controls was much easier when studying large brain sections. No ubiquitin-immunoreactive inclusions were found, except for sporadic tangles. The presence of a focal-GFAP positive astrocytosis as reported in the literature in the precentral cortex was confirmed. However, it was found to be nonspecific since it was also present outside the precentral cortex and in the cortex of normal control patients. No spatial relation was found between the distribution of the glial reaction in ALS and the areas containing neurons and boutons accumulating PNF.

Adult↗

PubMed1987

Tyrosine hydroxylase-immunoreactive intrinsic neurons in the rat cerebral cortex.

Using specific antisera against the catecholamine synthesizing enzyme, tyrosine hydroxylase (TH), in combination with the peroxidase-antiperoxidase method and/or the avidin-biotin complex method, we have found a new group of TH immunoreactive (TH-I) neurons in the rat cerebral cortex. Numerous TH-I cells were observed all over the isocortex, that is, frontal, temporal, parietal and occipital regions, and in some parts of the allocortex such as the anterior cingulate cortex, the retrosplenial cortex and anterior part of the insular cortex. In contrast, they were rare in the perirhinal cortex, posterior part of the insular cortex, piriform cortex, entorhinal cortex and hippocampal formation. TH-I cells were situated throughout all cortical layers, but were most concentrated in layer II/III. Although TH-I cells were heterogeneous in shape, the majority were bipolar. All TH-I cells so far examined appeared to be of the nonpyramidal type. The majority of these intrinsic TH-I neurons also contained the GABA-like immunoreactivity and thus could be regarded as a subpopulation of cortical GABAergic neurons.

Animals↗

PubMed1987

The role of the monkey sensory cortex in the recovery from cerebellar injury.

The aim of the study was to investigate the contribution of the primary sensory cortex in the compensation of cerebellar deficits during self-paced movements. For this purpose, monkeys were trained on motor tasks which required goal-reaching and independent finger movements. The intermediate and lateral deep cerebellar nuclei and the sensory cortex were lesioned in isolation and in sequence and the course of motor recovery was studied on the test performances. The deep nuclei were lesioned by kainic acid injections, the sensory cortex was removed by ablation. Cerebellar lesions in isolation produced obvious deficits at proximal and distal joints, affecting both slow and fast motor adjustments. Only lesions of the anterior portions of the intermediate and lateral deep nuclear complexes produced deficiencies in voluntary movements. Lesions of the posterior portions produced postural disturbances. The process of recovery following cerebellar lesions was slow and, depending on the nature of the task, was found to be differentially disruptive for motor performances requiring fast and slow motor adjustments. The deficits at distal joints appeared to be more enduring than those at proximal joints. Sensory cortical lesions in isolation produced much less severe and more transient motor deficits. They consisted of hand clumsiness and their recovery was fast and reached higher levels of performance than following cerebellar lesions. When the sensory cortex was removed secondarily to a cerebellar lesion and after recovery from the cerebellar deficits, the initially recovered motor performance became much worse again (decompensation). Removal of the sensory cortex prior to a cerebellar lesion exaggerated the cerebellar deficits and severely limited their recovery. Slow and fast motor performances were completely abolished for three weeks following sequential lesions. Signs of recovery subsequently appeared and stabilized at low levels of performance by five to seven weeks. The effects of combined, sequential cerebellar and sensory cortical lesions were much worse than expected if the effects from the two lesions were merely additive. This indicates that there is some functional interrelationship between the sensory cortex and the cerebellum, which promotes compensation. The somatosensory cortex appears to play a crucial role in the process of recovery from cerebellar motor deficits and it is likely that sensation is an important component in the process of recovery. It is suggested that the sensory cortex exerts its compensatory actions via a structure or structures which receives convergent cerebellar and sensory cortical inputs.

Adaptation, Physiological↗

PubMed1995

Expression of calcium-binding protein regucalcin mRNA in the kidney cortex of rats: the stimulation by calcium administration.

The expression of calcium-binding protein regucalcin mRNA in the kidney cortex of rats was investigated. The change of regucalcin mRNA levels was analyzed by Northern blotting using liver regucalcin complementary DNA (0.9 kb of open-reading frame). Regucalcin mRNA was expressed in the kidney cortex, and this expression was clearly increased by a single intraperitoneal administration of calcium chloride solution (5-15 mg Ca/100 g body weight) in rats; this increase was remarkable at 60-120 min after the administration. Thyroparathyroidectomy (TPTX) caused a slight decrease of regucalcin mRNA levels in the kidney cortex. However, the administration of calcium (10 mg/100 g) in TPTX rats produced a clear increase of regucalcin mRNA levels in the kidney cortex. The subcutaneous administration of calcitonin (10-100 MRC mU/100 g) or parathyroid hormone [1-34] (1-10 U/100 g) in TPTX rats which received calcium (10 mg/100 g) administration did not cause an appreciable alteration of regucalcin mRNA levels in the kidney cortex, suggesting that the mRNA expression is not stimulated by calcium-regulating hormones. The administration of trifluoperazine (TFP; 5 mg/100 g), an inhibitor of Ca2+/calmodulin action, completely blocked the expression of regucalcin mRNA stimulated by calcium administration. Now, calcium content in the kidney cortex was significantly elevated by a single intraperitneal administration of calcium (10 mg/100 g) in rats. The present study clearly demonstrates that the expression of regucalcin mRNA in the kidney cortex is stimulated by calcium administration in rats. This expression may be mediated through Ca2+/calmodulin action in the kidney cortex.

Adrenal Glands↗

PubMed2003

Constitutive and inducible levels of CYP1A1 and CYP1A2 in rat cerebral cortex and cerebellum.

We examined the constitutive and inducible levels of microsomal cytochromes P450 1A1 and 1A2 (CYP1A) in rat cerebral cortex and cerebellum at the level of proteins by western blot analysis, and by catalytic activities via ethoxyresorufin O-deethylase (EROD) and methoxyresorufin O-demethylase (MROD). In the cerebral cortex, cytochrome P450 1A1 (CYP1A1) protein was more abundant than cytochrome P450 1A2 (CYP1A2) protein. Treatment with beta-naphthoflavone (beta-NF) caused a slight decrease in the level of the former but induced the latter 5.8-fold. In the cerebellum, in contrast to the cerebral cortex, CYP1A1 protein was less abundant than CYP1A2 protein in untreated rats, and while beta-NF treatment caused a 3.3-fold induction of CYP1A1 protein, it resulted in a 10-fold decrease in CYP1A2 protein. The CYP1A-preferential activity EROD was 2.3-fold higher in the cerebellum than in the cerebral cortex, and was induced 1.5-fold and 1.9-fold in the cerebellum and cerebral cortex, respectively, by beta-NF treatment. The CYP1A2-preferential activity MROD was 3-fold higher in the cerebellum than in the cerebral cortex, and was repressed 2.2-fold in the cerebellum but induced 3.7-fold in the cerebral cortex following beta-NF treatment. The results show that CYP1A1 and CYP1A2 proteins and catalytic activities are constitutively expressed in brain but are differentially inducible in the rat cerebral cortex and cerebellum.

Animals↗

PubMed1997

On the presence of dendrite bundles in the cerebral cortex of the Madagascan lesser hedgehog tenrec and the red-eared pond turtle.

In mammals with a well-differentiated neocortex apical dendrites of pyramidal cells form vertical bundles. Little is known about the presence of dendrite bundles in animals with a poorly differentiated cortex. In this paper the presence of dendrite bundles has been investigated in the lesser hedgehog tenrec, Echinops telfairi, a basal insectivore with a very low degree of neocorticalization. In a further step the arrangement of dendrites has been analyzed in the cerebral cortex of the red-eared pond turtle, Pseudemys scripta elegans. Among non-mammalian vertebrates, reptiles have a cerebral cortex that is relatively most comparable with the mammalian one, and the cerebral cortex of turtles shows more structural and functional similarities with the cortex in mammals than those of other reptiles. In the hedgehog tenrec, bundles of apical dendrites are found in all neo-cortical areas, the cingulate and retrosplenial cortices. The shape and arrangement of dendrite bundles are primarily determined by apical dendrites of lamina V pyramids. Apical dendrites originating in laminae III/IV or VI join these bundles, and do not give rise to separate sets of bundles in the supra- and infragranular layers as in other mammals. Center to center distances between bundles determined in the neocortical areas A(2-4) range from 7 to 76 microm, with an average of 32 microm. Area-specific differences are found concerning the length of bundles as well as the number, caliber, branching pattern and packing density of dendrites sharing an individual bundle. In the three-layered entorhinal cortex and the hippocampus dendrite bundles are not observed. In the turtle, no vertical bundles of dendrites are seen either in the medial, dorsomedial or medial part of the dorsal cortex. Only in the lateral part of the dorsal cortex are isolated bundles of apical dendrites originating from groups of perikarya situated below the main level of lamina II detected. Our findings suggest that the presence of dendrite bundles is closely related with the multilayered nature of the mammalian neocortex.

Animals↗

PubMed2001

Nitric oxide synthase and cytochrome c oxidase changes in the tumoural and peritumoural cerebral cortex.

BACKGROUND: We analysed changes in nitric oxide synthase (NOS) and cytochrome oxidase (CO) activities in the tumoural and peritumoural cerebral cortex in order to investigate: a) the role of NO in tumourigenesis, in TBF regulation, and in vasogenetic PBE; b) the metabolic changes caused by the neoplasm in the surrounding tissues. METHOD: Intra-operative samples of cerebral cortex were studied by means of immunohistochemistry for nNOS and iNOS, and by histochemistry for NADPH-diaphorase (NADPH-d) and CO. FINDINGS: In contrast with normal cortex, reactive glial cells and the endothelium of small blood vessels displayed strong NADPH-d and iNOS activities in oedematous peritumoural tissue. In the tumoural cortex, NADPH-d and nNOS-positive neurones were reduced in number and their dendrites were thin and interrupted, and infiltrates of NADPH-d and iNOS-positive tumoural cells were frequent. CO activity was decreased in the deep layers of peritumoural cortex, and it was almost absent in the tumoural cortex. INTERPRETATION: In peritumoural and tumoural cortex changes in NOS and CO activities suggest that the coupling between neuronal activity and blood flow is impaired in the damaged cerebral cortex, and that the increase in NOS activity may play a role in tumour vascularization and progression.

Adenocarcinoma↗

PubMed1980

Prestriate afferents to inferior temporal cortex: an HRP study.

The inferior temporal (IT) cortex of 6 macaques was injected with horseradish peroxidase. HRP-labeled cells were found throughout IT cortex itself (outside the injection area) but were not found in the polysensory areas that surround IT dorsally, anteriorly and ventrally. Posterior to IT, labeled cells were found in the anterior parts of prestriate cortex. In one animal, the anterior prestriate region was injected with HRP. Labeled cells were then found in the regions of posterior prestriate cortex that receive direct projections from striate cortex. These results suggest that IT cortex receives information from striate cortex after at least two stages of processing in prestriate cortex.

Animals↗

PubMed1981

Responses to cortical injury: II. Widespread depression of the activity of an enzyme in cortex remote from a focal injury.

As a part of a broader study of the reaction of the brain to injury, we report here an interesting loss of the activity of an enzyme in areas quite remote from the site of direct injury. At 36 h following a laceration or contusion injury to the hindpaw area of the motor cortex, a peculiar loss of staining for the enzyme alpha glycerophosphate dehydrogenase (alpha-GPDH) was noted. alpha-GPDH activity was markedly depressed in cortical layers II and III throughout the hemisphere on the side of the injury. The depression of alpha-GPDH activity extended far laterally across the rhinal fissure into the pyriform cortex. The decrease in alpha-GPDH staining was prominent 4 days after the injury: however, the staining pattern had returned to normal at 9 days. Enzyme changes in animals lesioned in the occipital cortex paralleled that seen in animals with a lesion in the motor cortex. Animals which had received an undercut lesion in the motor cortex 56 days earlier were contused in the occipital cortex. The old injury site presented the same sequelae of changes as seen in other lesioned animals. Additionally, a suction ablation injury involving only a small part of motor cortex resulted in the same widespread reduction of staining for alpha-GPDH in layers II and III. The derangement in energy metabolism suggests that cells in layers II and III of the cerebral cortex may be particularly vulnerable to perturbations induced by cortical trauma. These findings may be related to the diffuse and transient functional losses observed after head injury in man.

Animals↗

PubMed1983

Evidence for some collateralization between cortical and diencephalic efferent axons of the rat subicular cortex.

The present study has used the fluorescent dye tracing technique in order to determine the exact location of neuronal somata within the subicular cortex which project to the diencephalon, telencephalon (entorhinal cortex), or to both via axonal collaterals. The greatest collateralization to the two sites is found in the neurons of the subiculum proper. In this region approximately one-third of all neurons project to both the entorhinal cortex and the hypothalamus (either the mammillary bodies or the ventral medial hypothalamic nucleus). The hypothalamic and cortical projection cell bodies in this region are intermingled extensively with each other. In the cytoarchitectonically more organized regions of the subicular cortex, i.e. the pre-, para- and postsubiculum, the situation is quite different. In these areas neurons project to the hypothalamus or entorhinal cortex but very seldom does a single neuron project to both areas, and the neuronal somata are spatially segregated according to their projections. The entorhinal cortex projecting somata are located in layer two whereas the hypothalamic neurons are in the deeper layer. The somata projecting to the thalamus are the most deeply located neurons in all regions of the subicular cortex, and extremely few collateralize to the entorhinal cortex.

Animals↗