Left-right asymmetry of the temporal and parietal regions in children: based on the medullary pattern of cerebral white matter

Summary Lateralization of the posterior temporal lobe and inferior parietal lobule in childhood was studied on CT of 276 cases and compared with those in adulthood of 371 cases. CT images were analized based on the morphological features of medullary branches of the cerebral white matter. In children below 5 years of age, the left planum temporale was already more posteriorly located than the right in 56%, while the right was more so in 21%. The asymmetry of the middle temporal gyrus was similar to those of the planum temporale. The folding of the inferior parietal lobule was extensive and intricate on the left side in 63% and on the right side in 8% of children, almost identical to those in the adult. The visualization rates of the intraparietal sulcus were lower compared to those of the adult, but the higher visualization of the left side was a common tendency regardless of age. These alterations in left-right asymmetry seemed to be a morphologic substratum indicating the processes of localization of auditory function to those association areas.

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Asymétrie gauche-droite dans les régions temporales et pariétales par l'étude des ramifications de la substance blanche (RSB) cérébrale chez l'enfant

Résumé La latéralisation de la partie postérieure du lobe temporal et du lobe pariétal inférieur chez l'enfant a été étudiée en TDM sur 276 cas et comparée avec celle de l'adulte dans 371 cas. Les images TDM des ramifications médullaires de la substance blanche cérébrale furent analysées. Chez l'enfant en dessous de 5 ans d'âge, le planum temporale gauche est plus postérieur que le droit dans 56 % des cas; le droit est plus postérieur dans 21 %. L'asymétrie du gyrus temporal moyen est similaire à celle du planum temporal. La plicature (gyration) du lobule pariétal inférieur est massive et importante du côté gauche dans 63 % et dans 8 % du côté droit, chiffre à peu près identique à ceux de l'adulte. Le degré de visualisation du sillon intrapariétal est inférieur à celui de l'adulte mais la meilleure visualisation du côté gauche est un phénomène commun quel que soit l'âge incriminé. Ces altérations droitegauche semblent être le substrat morphologique des processus de localisation de la fonction auditive dans ces zones d'association.

     

Calcium binding proteins and neuropeptides as molecular markers of GABAergic interneurons in the cat visual cortex

Summary In the cat visual cortex, almost all parvalbumin-positive cells are GABAergic, and about 80% of the calbindin D-28K-positive neurons are also GABA-immunoreactive. About 37% of the GABAergic neurons contain parvalbumin and a smaller fraction (about 18%) contains calbindin. Furthermore, parvalbumin and calbindin are localized in two separate neuronal populations in the cat visual cortex, suggesting that two GABAergic populations can be distinguished, one containing parvalbumin and one containing calbindin. Double staining for parvalbumin and neuropeptides (CCK, SRIF and NPY), revealed no double-labeled cells, with the exception of a few SRIF- and parvalbumin-positive neurons. These results show that cortical GABAergic cells can be differentiated on basis of their calcium binding protein and neuropeptide immunoreactivity.     

Suppressive regions in the visual receptive fields of single cells of the pigeon's optic tectum

Summary Intracellularly HRP-labelled cat hindlimb -motoneurones were reconstructed light microscopically from a series of 1 m or 2 m thick consecutive sections. The volume and surface area of the soma as well as the size of the very proximal part of the dendritic and axonal processes were estimated morphometrically. Similar measurements were also made on adjacent unlabelled neurons in the same series of sections. A close relation was found between the soma volume and surface area on one hand the combined cross-sectional area of the proximal dendrites and axon on the other. The combined axonal and dendritic bases occupied on the average 16% of the soma surface. The accuracy in using the diameters and cross-sectional area of the cell body as indirect estimates of soma volume and surface area was analyzed. Combined measurements in both the transversal and sagittal planes were then found to yield more satisfactory estimates then when the measurements were confined only to the transversal plane. Several different formulas using the soma axes for indirect calculations of the soma volume and surface area were compared with respect to the accuracy of the results.     

Dark-reared kittens: GABA sensitivity of cells in the visual cortex

Summary Most cells in the visual cortex of dark-reared kittens are unselective for stimulus orientation and we examined the notion that this might be due to insufficiently developed gamma-aminobutyric acid (GABA) receptors. We recorded from cortical neurons and examined their sensitivity to iontophoretically applied GABA. As expected, most units were non-selective for orientation, but application of GABA suppressed impulse activity of these cells just as for orientation selective neurons. This result suggests that the development or maintenance of GABA receptors is not critically dependent on visual experience.On leave from NHK Science and Technical Research Laboratories, Kinuta, Setagaya-ku, Tokyo 157, Japan     

Sustained expression of parvalbumin immunoreactivity in the hippocampal CA1 region and dentate gyrus during aging in dogs

The hippocampus contains a heterogeneous population of interneurons. Parvalbumin (PV) positive neurons constitute an abundant subpopulation of cells that express GABA. The authors observed PV immunoreactivity in the hippocampal CA1 region and dentate gyrus of variously aged dogs. In 1-year-old dogs, PV immunoreactive neurons were detected in the stratum oriens of the CA1 region, and in the polymorphic layer of the dentate gyrus. In addition, weak PV immunoreactive fibers were observed in all layers in the CA1 region and dentate gyrus. In 3-year-old dogs, PV immunoreactivity was significantly higher in the CA1 region and dentate gyrus, and this was maintained in 10-year-old dogs. This finding suggests that PV immunoreactive interneurons may show high resistance to age-dependent neurodegenerative processes.     

Temporal shaping of phasic neuronal responses by GABA- and non-GABA-mediated mechanisms in the somatosensory thalamus of the rat

Trapezoidal mechanical movement of whiskers was used to study the responses of 44 single thalamic ventral posteromedial (VPM) neurons to dynamic and static stimulus components in urethane-anesthetized rats. The effects of local administration of the GABA_A receptor antagonist, bicuculline, and the GABA_B receptor antagonist, 2-hydroxysaclofen, were tested to determine whether and to what extent the responses altered when GABA-mediated inhibitory synaptic transmission was blocked. Two classes of phasically responding neurons were identified, ON/OFF and movement-sensitive types. Bicuculline enhanced the magnitudes of the responses from both types by 2.5-fold and ON/OFF responses were converted to movement-sensitive ones in 17 (43%) of the 40 ON/OFF neurons. 2-hydroxysaclofen either had no effect or appeared to act like a GABA agonist. In 21 (48%) neurons, a significantly reduced responsiveness was observed during a 100-ms period following the ON and OFF responses. This discharge suppression was especially prominent during the plateau phase of the stimulus, and in some cases extended for several 100 ms following its onset. This suppression was overcome neither by the GABA receptor antagonists, nor by ejection of AMPA or glutamate at currents that otherwise produced vigorous excitation. These results suggest that one functional role for GABA_A-receptor-mediated synaptic inhibition in the somatosensory thalamus is the intramodal regulation of the form of expression of phasically responding neurons. Other thalamic inhibitory processes not mediated by GABA_A or GABA_B receptors that help to shape the expression of the responses of certain phasic neurons to maintained stimulation may exist. Overall, these mechanisms appear to mediate the precision of timing of thalamic neuronal firing in response to the rats tactile environment.Due to an error in the citation line, this revised PDF (published in December 2003) deviates from the printed version, and is the correct and authoritative version of the paper.     

Early visual deafferentation of the cortex results in an asymmetry of somatostatin labelled cells

Summary Biologically active peptides are distributed widely throughout the nervous system. The distribution of each is not random, but follows a relatively specific pattern. Although the time course of development of a number of peptides has been traced, the factors which determine their distribution and function remain unknown. In this study we report changes which occur preferentially in the distribution of one peptide, somatostatin, in the visual cortex of the rat, as a consequence of early unilateral eye removal. Because the uncrossed retinal projection is so small in the rodent, this manipulation substantially reduces the visual innervation of the cortex ipsilateral to the remaining eye, and is correlated here with an asymmetry in the number of somatostatin positive cells.     

Catecholaminergic neurons containing GABA-like and/or glutamic acid decarboxylase-like immunoreactivities in various brain regions of the rat

Summary The coexistence of immunoreactivities for tyrosine hydroxylase (TH) and glutamic acid decarboxylase (GAD) and/or gamma-aminobutyric acid (GABA) was revealed in various brain regions in colchicine-injected and untreated rats, using the peroxidase-antiperoxidase method. Consecutive 40 m thick Vibratome sections were incubated in different antisera and those cells which were bisected by the plane of sectioning so as to be included at the paired surfaces of two adjacent sections were identified. The coexistence of the immunoreactivities for TH and GAD or GABA in the same cell could thus be determined by observing the immunoreactivity of the two halves of the cell incubated in two different antisera. In the olfactory bulb, retina, diencephalon, mesencephalic central grey and cerebral cortex, many TH-like immunoreactive neurons also showed GAD-like or GABA-like immunoreactivity, whereas in the substantia nigra, ventral tegmental area and locus ceruleus none of TH-like immunoreactive neurons showed either GAD-like or GABA-like immunoreactivity. In the olfactory bulb, retina and cerebral cortex, the majority of the TH-like immunoreactive neurons were also GAD-like or GABA-like immunoreactive. In the diencephalon of colchicine-injected rats, at least one-third of the TH-like immunoreactive neurons were GAD-like immunoreactive. Using serial 0.5 m thick plasticembedded sections, it was shown that immunoreactivities for three antigens, GAD, GABA and TH could occur in the same neurons in the olfactory bulb. These observations indicate the possible coexistence of two classical transmitters, GABA and catecholamine, in various brain regions of the rat.     

Cholinergic neurons containing GABA-like and/or glutamic acid decarboxylase-like immunoreactivities in various brain regions of the rat

Summary The coexistence of immunoreactivities for choline acetyltransferase (ChAT) and glutamic acid decarboxylase (GAD) and/or gamma-aminobutyric acid (GABA) was revealed in some brain regions of the rat, using the peroxidase-antiperoxidase method. Consecutive 40 m thick vibratome sections were incubated in different antisera and those cells which were bisected by the plane of sectioning so as to be included at the paired surfaces of two adjacent sections were identified. The coexistence of the immunoreactivities for ChAT and GAD or GABA in the same cell could thus be determined by observing the immunoreactivity of the two halves of the cell incubated in two different antisera. In the retina, cerebral cortex, basal forebrain and spinal cord, colocalization of ChAT-like and GAD-like or GABA-like immunoreactivities was observed in some cell types, whereas no such colocalization was observed in cells in the striatum or brainstem. In the retina, the majority of ChAT-like immunoreactive (ChAT-LI) amacrine cells contained GABA-like or GAD-like immunoreactivity. About half of the ChAT-LI neurons in the cerebral cortex showed GABA-like immunoreactivity. In the basal forebrain only a small proportion of ChAT-LI neurons (0.6%) contained GAD-like immunoreactivity. In the spinal cord, about one-third of ChAT-LI central canal cluster cells and about half of ChAT-LI dorsal horn cells showed GAD-like and/or GABA-like immunoreactivities. These observations indicate the possible coexistence of two classical transmitters, GABA and acetylcholine, in various brain regions and spinal cord of the rat.This paper is dedicated to Prof. Hama on the occasion of his 66th birthday     

The birthdates of GABA-immunoreactive amacrine cells in the rat retina

The birthdates of GABAergic amacrine cells in the rat retina were investigated by immunocytochemistry using anti-GABA and anti-bromodeoxyuridine (BrdU) antisera. The ratio of co-localization of GABA to BrdU increased gradually from embryonic-day 13 (E13) and showed a peak value on E18 in the central retina and on E20 in the periphery. After birth, until postnatal-day 3 (P3), a few co-localized cells were observed in the inner nuclear layer (INL). However, in the peripheral retina, co-localized cells were observed in the INL and ganglion cell layer until P5. Our results suggest that the birthdates of GABA-immunoreactive cells vary, depending on cell-type and that there is a temporal lag in the GABA-immunoreactive cell production in the peripheral retina relative to the central retina. Received: 11 January 1999 / Accepted: 20 April 1999     

Differential responsiveness of cells in the visual zones of the cat's LP-pulvinar complex to visual stimuli

Summary Multiple visual field representations are contained within the feline LP-pulvinar complex; regions differentiated by their afferent and efferent connectivity patterns as the striate-, tecto- and retino-recipient zones. Cell responses from these visuotopic zones were investigated in immobilized cats under N₂O/O₂ supplemented with pentobarbitone or Althesin, using spot, bar and textured stimuli.Response fields recorded within the LP-pulvinar complex were classified as diffuse, concentric, movement-, direction- or orientation-sensitive. Concentric receptive fields were further classified as sustained (X), transient (Y) or tonic/phasic W-cells. Direction-and movement-sensitive cells predominated in the striate- and tecto-recipient zones, respectively. Motion of noise fields, or noise bars against an identical stationary noise background elicited vigorous responses from cells in the striate zone, many showing a preference for noise stimuli. In contrast, cells from the tectal zone and other divisions of the LP-pulvinar complex were insensitive to noise. The retino-recipient zone at the lateral margin of the pulvinar nucleus was characterized by cells with concentric receptive fields, the majority exhibiting properties similar to W-cells in the LGNd. The evidence supports the notion of functional subdivision within the LP-pulvinar complex corresponding to the visuotopically organized regions defined by their connectivity patterns. Consideration of the retino-recipient zone as an extension of the LGNd-MIN complex is discussed.Supported by the MRC (Grant No. 976/64/N)     

GABAergic interneurons and neuropil of the intralaminar thalamus: an immunohistochemical study in the rat and the cat,with notes in the monkey

Summary Immunohistochemistry using antibodies to glutamic acid decarboxylase (GAD) was used to investigate the intralaminar nuclei of the thalamus in rat, cat and monkey. Antibodies to gamma aminobutyric acid (GABA) were also used in the cat. Intralaminar immunoreactive cell bodies were not detected in the rat, but were clearly present in cat and monkey. In the latter species, GABA- or GAD-immunopositive perikarya were distributed throughout the anterior intralaminar nuclei, whereas in the posterior intralaminar complex they prevailed in the lateral part of the centre median nucleus and around the fasciculus retrofiexus. Measurements of the area of immunostained intralaminar cell bodies in cat and monkey indicated that they are represented by small neurons. Experiments in the cat, based on retrograde tracers injections involving large sectors of the frontal and parietal cortices and the head of the caudate nucleus, revealed that the GABA- or GAD-immunoreactive cells and the retrogradely labeled projection neurons represented two separate intralaminar cell populations, although the latter also included small cells. Considerable differences were observed in the immunoreactive GABAergic neuropil of the anterior and posterior intralaminar nuclei. Clusters of densely packed bouton-like immunoreactive elements were detected in the former structures in the rat, cat and monkey, and were especially evident in the central lateral nucleus; immunopositive varicose fibers and puncta were diffusely distributed in the posterior intralaminar structures. Taken together with data from the literature, the present findings indicate that in cat and monkey local circuit inhibitory cells regulate not only the activity of principal thalamic nuclei which project densely upon restricted cortical fields, but also of the intralaminar structures which are widely connected with the cerebral cortex and the striatum. Regional variations in the distribution of GABAergic fibers and terminals suggest major differences in the organization of inhibitory circuits and synaptic arrangements of the anterior and posterior intralaminar thalamus.Abbreviations CeM central medial nucleus - CL central lateral nucleus - CM-Pf centre median-parafascicular complex - fr fasciculus retrofiexus - Hb habenular complex - LD laterodorsal nucleus - LP lateroposterior nucleus - MD mediodorsal nucleus - Pc paracentral nucleus - PO thalamic posterior complex - PvA anterior paraventricular nucleus - Sm stria medullaris - VL ventral lateral nucleus - VP ventroposterior complex     

Effects of restraint and haloperidol on sensory gating in the midbrain of awake rats

Deficits in sensory processing have been reported to be associated with an array of neuropsychiatric disorders including schizophrenia. Auditory sensory gating paradigms have been routinely used to test the integrity of inhibitory circuits hypothesized to filter sensory information. Abnormal dopaminergic neurotransmission has been implicated in the expression of schizophrenic symptoms. The aim of this study was to determine if inhibitory gating in response to paired auditory stimuli would occur in putative dopaminergic and non-dopaminergic midbrain neurons. A further goal of this study was to determine if restraint, a classic model of stress known to increase extracellular dopamine levels, and systemic haloperidol injections affected inhibitory mechanisms involved in sensory gating. Neural activity in the rat midbrain was recorded across paired auditory stimuli (first auditory stimulus (S1) and second auditory stimulus (S2)) under resting conditions, during restraint and after systemic haloperidol injections. Under resting conditions, a subset of putative GABA neurons showed fast, gated, short latency responses while putative dopamine neurons showed long, slow responses that were inhibitory and ungated. During restraint, gated responses in putative GABAergic neurons were decreased (increased S2/S1 or ratio of test to conditioning (T/C)) by reducing the response amplitude to S1. Systemic haloperidol decreased the T/C ratio by preferentially increasing response amplitude to S1. The results from this study suggest that individual neurons encode discrete components of the auditory sensory gating paradigm, that phasic midbrain GABAergic responses to S1 may trigger subsequent inhibitory filtering processes, and that these GABAergic responses are sensitive to restraint and systemic haloperidol.     

The immunocytochemical distribution of calbindin-D28k and parvalbumin in identified neurons of the pulvinar-lateralis posterior complex of the cat

The calbindin-D28k and parvalbumin immunoreactivities of the neurons of the pulvinar-lateral posterior complex (Pul-LP) were studied in the cat. The neurons of the Pul-LP projecting to the cerebral cortex were identified by a retrogradely transported tracer injected in the suprasylvian gyrus. Two populations of cells were found, a calbindin-D28k-immunoreactive, large-diameter population and a parvalbumin-immunoreactive, small-diameter group. The two kinds of cells are closely intermingled. The former includes the neurons retrogradely marked, and therefore projecting to the suprasylvian gyrus. The latter includes neurons which were not retrogradely marked, and therefore presumably intrinsic elements.     

Dendritic arborization patterns of cortical interneurons labeled with the lectin, Vicia villosa, and injected intracellularly with lucifer yellow in aldehyde-fixed rat slices

Neurons whose cell bodies had been stained by a lectin, Vicia villosa, which recognizes terminal N-acetylgalactosamine residue, were intracellularly injected with Lucifer yellow (LY), in aldehyde-fixed slices of the parietal cortex of rats. LY was subsequently visualized immunocytochemically. All injected neurons had smooth or only sparsely spiny dendrites and resembled the various forms of gamma-aminobutyric acid-ergic neurons previously described in rat neocortex. In layers II/III, IV and V, most injected neurons were multipolar. In layer VI, most had vertically elongated dendritic fields. Some injected neurons in layer IV had an oval or vertically elongated soma and a bitufted dendritic arborization pattern. There was a gradual increase in the overall dendritic extent in deeper layers of the cortex.     

Comparative study on the offset responses of simple cells and complex cells in the primary visual cortex of the cat

Simple and complex cells are two basic and distinct functional types of neurons in the mammalian primary visual cortex. Here, we studied the onset response and the offset response of simple and complex cells to a flashing visual stimulus in the cat's area 17. Compared with simple cells, complex cells exhibited greater similarity between the onset and offset responses in peak latency. For simple cells, onset response had greater peak amplitude and signal-to-noise ratio than offset response, and for complex cells, vice versa. For both types of cortical cells, the amplitude of offset responses increased with stimulus duration within 100 ms significantly, while the onset response did not. However, to elicit a detectable offset response, complex cells tended to require shorter stimulus duration than simple cells did. In regard to the similarity of psychophysical data, these results suggest that the rebound offset response of cortical cells to disappearance of a visual pattern might be correlated to visual persistence in humans.     

褶纹冠蚌的脑、足神经节内Glu、GABA、5-HT、ACh和DA能神经元的分布

目的:观察谷氨酸(glutamate,Glu)、γ-氨基丁酸(γ-aminobutyric acid,GABA)、5-羟色胺(5-hydroxytryptamine,5-HT)、乙酰胆碱(acetylcholine,ACh)和多巴胺(dopamine,DA)神经元在褶纹冠蚌中枢神经系统内的分布。方法:免疫组织化学染色技术和免疫印迹技术。结果:脑神经节外侧胞体层存在大量的GABA能神经元,偶见胞体较大的Glu、5-HT、ACh和DA能神经元,其中央纤维网可见丰富的GABA能神经末稍及少量的Glu、5-HT、ACh和DA能神经末梢。足神经节外侧胞体层亦含有大量的GABA能神经元,可见散在的Glu、5-HT、ACh和DA能神经元,其中央纤维网可见丰富的GABA能神经末稍及零星的Glu、5-HT、ACh和DA能神经末梢。结论:褶纹冠蚌脑和足神经节均含有GABA、Glu、5-HT、ACh和DA能神经元,但这五类神经元的数量和密度有所不同。     

Differential responsiveness of simple and complex cells in cat striate cortex to visual texture

Summary The responsiveness of 254 simple and complex striate cortical cells to various forms of static and dynamic textured visual stimuli was studied in cats, lightly anaesthetised with N₂O/O₂ mixtures supplemented with pentobarbitone.Simple cells were unresponsive to all forms of visual noise presented alone, although about 70% showed a change in responsiveness to conventional bar stimuli when these were presented on moving, rather than stationary, static-noise backgrounds. Bar responses were depressed by background texture motion in a majority of cells (54%), but were actually enhanced in a few instances (16%).In contrast, all complex cells were to some extent responsive to bars of static visual noise moving over stationary backgrounds of similar texture, or to motion of a whole field of static noise. The optimal velocity for noise was generally lower than for bar stimuli.Since moving noise backgrounds were excitatory for complex cells, they tended to reduce specific responses to bar stimulation; in addition, directional bias could be modified by direction and velocity of background motion.Complex cells fell into two overlapping groups as regards their relative sensitivity to light or dark bars and visual noise. Extreme examples were insensitive to conventional bar or edge stimuli while responding briskly to moving noise.In many complex cells, the preferred directions for motion of noise and of an optimally oriented black/white bar were dissimilar.The ocular dominance and the degree of binocular facilitation of some complex cells differed for bar stimuli and visual texture.Preliminary evidence suggests that the deep-layer complex cells (those tolerant of misalignment of line elements; Hammond and MacKay, 1976) were most sensitive to visual noise. Superficial-layer complex cells (those preferring alignment) were less responsive to noise.Only complex-type hypercomplex cells showed any response to visual noise.We conclude that, since simple cells are unresponsive to noise, they cannot provide the sole input to complex cells. The differences in the response of some complex cells to rectilinear and textured stimuli throw a new light on their rôle in cortical information-processing. In particular, it tells against the hypothesis that they act as a second stage in the abstraction of edge-orientation.