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Temporal lobe is known to perform vital role in visual discrimination and identification of objects. Cresyl violet and Golgi studies of temporal region of Indian gray mongoose revealed diversity of neurons dispersed in six layers of the region. Pyramidal neurons were observed to outnumber the other four types of neurons in the temporal region supporting the specialization of this brain region as compared to primitive brains of monotremes and insectivores. Moreover, specialization of neurons provides better functioning and refining learning and predatory behavior of the animal.

Background: Cardiac remodeling underpinning progressive hypertensive heart disease alters the three-dimensional structure of the extracellular matrix, as well as the laminar organization of myocardial sheetlets. The effect of pharmacological intervention on microstructural remodeling is not known. Objective: To examine the changes in myocardial microstructure that occur as a result of hypertensive heart disease, and the effect of pharmacological treatment. Methods: The spontaneously hypertensive rat (SHR) model of hypertensive heart disease was studied, and compared with the normotensive Wistar Kyoto (WKY) rat, and SHRs treated with angiotensin converting enzyme inhibitors (TSHR). Cardiac magnetic resonance was used to assess cardiac function and ventricular geometry. Excised myocardium was stained (picrosirius red) for collagen and extended volume confocal microscopy used to produce high-resolution image stacks. Results: At 24 months, TSHRs had significantly greater ejection fraction (P

The subiculum is the major output component of the hippocampal formation and one of the major brain structures most affected by Alzheimer’s disease. Our previous work revealed a hidden laminar architecture within the mouse subiculum. However, the rotation of the hippocampal longitudinal axis across species makes it unclear how the laminar organization is represented in human subiculum. Using in situ hybridization data from the Allen Human Brain Atlas, we demonstrate that the human subiculum also contains complementary laminar gene expression patterns similar to the mouse. In addition, we provide evidence that the molecular domain boundaries in human subiculum correspond to microstructural differences observed in high resolution MRI and fiber density imaging. Finally, we show both similarities and differences in the gene expression profile of subiculum pyramidal cells within homologous lamina. Overall, we present a new 3D model of the anatomical organization of human subiculum and its evolution from the mouse.

The cerebral cortex is essential for integration and processing of information that is required for most behaviors. The exquisitely precise laminar organization of the cerebral cortex arises during embryonic development when neurons migrate successively from ventricular zones to coalesce into specific cortical layers. While radial glia act as guide rails for projection neuron migration, pre-formed vascular networks provide support and guidance cues for GABAergic interneuron migration. This study provides novel conceptual and mechanistic insights into this paradigm of vascular-neuronal interactions, revealing new mechanisms of GABA and its receptor-mediated signaling via embryonic forebrain endothelial cells. With the use of two new endothelial cell specific conditional mouse models of the GABA pathway (Gabrb3ΔTie2-Cre and VgatΔTie2-Cre), we show that partial or complete loss of GABA release from endothelial cells during embryogenesis results in vascular defects and impairs long-distance migration and positioning of cortical interneurons. The downstream effects of perturbed endothelial cell-derived GABA signaling are critical, leading to lasting changes to cortical circuits and persistent behavioral deficits. Furthermore, we illustrate new mechanisms of activation of GABA signaling in forebrain endothelial cells that promotes their migration, angiogenesis and acquisition of blood-brain barrier properties. Our findings uncover and elucidate a novel endothelial GABA signaling pathway in the CNS that is distinct from the classical neuronal GABA signaling pathway and shed new light on the etiology and pathophysiology of neuropsychiatric diseases, such as autism spectrum disorders, epilepsy, anxiety, depression and schizophrenia.

Dorsal premotor cortex is implicated in somatomotor decisions. However, we do not understand the temporal patterns and laminar organization of decision-related firing rates in dorsal premotor cortex. We recorded neurons from dorsal premotor cortex of monkeys performing a visual discrimination task with reaches as the behavioral report. We show that these neurons can be organized along a bidirectional visuomotor continuum based on task-related firing rates. “Increased” neurons at one end of the continuum increased their firing rates ~150 ms after stimulus onset and these firing rates covaried systematically with choice, stimulus difficulty, and reaction time—characteristics of a candidate decision variable. “Decreased” neurons at the other end of the continuum reduced their firing rate after stimulus onset, while “perimovement” neurons at the center of the continuum responded only ~150 ms before movement initiation. These neurons did not show decision variable-like characteristics. “Increased” neurons were more prevalent in superficial layers of dorsal premotor cortex; deeper layers contained more “decreased” and “perimovement” neurons. These results suggest a laminar organization for decision-related responses in dorsal premotor cortex., Dorsal premotor cortex (PMd) is thought to be involved in making somatomotor decisions. Chandrasekaran et al. investigated the temporal response dynamics of PMd neurons across cortical layers and show stronger and earlier decision-related responses in the superficial layers and more action execution-related signals in the deeper layers.

Olfactory dysfunction is associated with nearly all the cases of Parkinson’s disease (PD) and typically manifests years before motor symptoms are detected. The cellular mechanisms underlying this dysfunction, however, are not understood. In this study, olfactory bulbs (OBs) from male control and PD subjects were examined by histology for changes in cytoarchitecture. These studies found that the general OB laminar organization and the number of interneurons expressing tyrosine hydroxylase were unaltered. In contrast, the number of mitral/tufted projection neurons and interneurons expressing Calretinin were significantly decreased in PD subjects. This study reveals changes in OB cytoarchitecture mediated by PD and provides valuable insight into identifying specific OB neuronal populations vulnerable to PD-related neurodegeneration.

We report a unique case of cobblestone complex using post-mortem MR and diffusion tensor imaging to assess the laminar organization of the fetal cerebrum. The imaging findings were correlated with autopsy findings. Abnormal cortical development in cobblestone complex resulted in disruption of normal laminar organization of the fetal brain, which was seen as interruption and nodularity of the high-signal T1 cortical band with increased anisotropy and medium diffusivity extending beyond the cortical band into the cerebral mantle on post-mortem MR and diffusion tensor imaging.

Cortical layering is a hallmark of the mammalian neocortex and a major determinant of local synaptic circuit organization in sensory systems. In motor cortex, the laminar organization of cortical circuits has not been resolved, although their input-output operations are crucial for motor control. Here, we developed a general approach for estimating layer-specific connectivity in cortical circuits and applied it to mouse motor cortex. From these data we computed a laminar presynaptic --> postsynaptic connectivity matrix, W(post,pre), revealing a complement of stereotypic pathways dominated by layer 2 outflow to deeper layers. Network modeling predicted, and experiments with disinhibited slices confirmed, that stimuli targeting upper, but not lower, cortical layers effectively evoked network-wide events. Thus, in motor cortex, descending excitation from a preamplifier-like network of upper-layer neurons drives output neurons in lower layers. Our analysis provides a quantitative wiring-diagram framework for further investigation of the excitatory networks mediating cortical mechanisms of motor control.

This study was carried out to obtain fundamental information on the morphology of the primary taste center in the goatfish of genus Parupeneus. The primary taste center includes a dorsal facial lobe (dFL), ventral facial lobe (vFL) and vagal lobe (VL). The dFL is extraordinarily developed rostrocaudally to occupy the dorsal surface of the medulla. The vFL extends as a longitudinal column between the dFL and VL, and its rostral end connects to the proximal portion of the dFL at the level of most anterior medulla. The VL appears slightly caudal to the rostral end of vFL as a longitudinal column and reaches more caudally than the facial lobe (FL). The dFL includes tubercular and laminated structures. Each tubercle consists of four layers: a marginal layer, a superficial molecular layer, a cell-cluster layer and a deep layer. Sublaminar organization was also found in the cell-cluster layer. No laminar organization was found in either the vFL or VL but distinct clusters of small cells were frequently seen throughout both the lobes. Tracing experiments with the carbocyanine dye dil show that the facial fibers end in the entire dFL and vFL and the anterior portion of the intermediate nucleus of the facial lobe (NIF), while glossopharyngeal fibers terminate in the dorsolateral portion of the anterior VL and the intermediate portion of NIF. Trigeminal fibers project only to the most lateral aspects of the anterior vFL in addition to normal targets such as spinal trigeminal and medial funicular nuclei.

A comparative histochemical study of cytochrome oxidase (CO) activity in the superior colliculus (SC) of intact laboratory rats and animals with unilaterally lesioned inner ear cochlea was carried out. It was shown that distribution of CO activity in the SC of intact rats corresponded to its cytoarchitectonic laminar organization had a heterogeneous distribution between layers and homogeneous distribution inside the layers. Unilateral lesion of the inner ear cochlea results in the appearance of alternating columns with low and high CO activity in the medial complex layers and deep gray layer; these columns are directed mediolaterally and differentiated bilaterally. The appearance of the CO columns seems to be due to the spatially arranged organization of afferents coming onto SC from auditory structures.

Retinae of Borna disease virus (BDV)-infected Lewis rats were investigated with emphasis on long-term changes in organotypic tissue organization and glia-neuron relationship. Virus inoculation was attained via intracerebral BDV injection. Following survival times ranging between two and eight months, the retinal thickness was reduced up to one third of that of controls. Photoreceptor segments were completely extinguished and the number of neurons was dramatically reduced. The typical laminar organization of the retina was largely dissolved. Electron microscopy revealed severe spongy degeneration. Large numbers of activated microglia and macrophages were found, both cell types performing very active phagocytosis. The microglial cells expressed an extraordinary phenotype as characterized by large numbers of processes, with some of them penetrating the endfeet of Muller cells and others establishing highly complex interdigitations with vacuolized swellings and endings of neuronal processes. Muller cells were not reduced in number but displayed clear indications of gliosis such as alterations in the immunoreactivity for filament proteins and glutamine synthetase, significantly thickened stem processes, and an altered pattern of K+ currents in patch-clamp recordings. These findings demonstrate for the first time long-term neuron-glia interactions in the retina of BDV-infected rats. Moreover, the data contribute to our knowledge on structural and functional alterations accompanying persisting virus infection in the central nervous system.

The rat fascia dentata is characterized by a simple cytoarchitecture and characteristic lamination of afferents. Entorhinal afferents are believed to terminate exclusively in the outer two thirds of the molecular layer, whereas commissural fibers are believed to terminate exclusively in the inner molecular layer of the fascia dentata. A sharp border divides these two major afferent fiber systems and is regarded as the main boundary of the fascia dentata. This concept of a highly laminated brain structure has made the fascia dentata attractive for studies analyzing normal or pathological processes of the brain. Recently, entorhinal as well as commissural fibers have been identified which do not follow the classical lamination of the fascia dentata. Using anterograde tracing with Phaseolus vulgaris-Leucoagglutinin, an entorhino-dentate projection to the molecular layer, granule cell layer, and hilus of the fascia dentata was described. With the same technique, GABAergic commissural fibers to the outer molecular layer of the fascia dentata were revealed and a previously unknown heterogeneity of the commissural projection was demonstrated. These previously unknown fiber systems complicate the interpretation of lesion effects in this brain region and have to be taken into account as possible sources of sprouting fibers following the partial denervation of the fascia dentata.

The rat motor cortex, like other areas of the mammalian neocortex, is organized in a 6-layered structure. The synaptic organization has been studied in the past by various in vitro techniques [1,2], and the movement-specific tuning properties of the neurons in forelimb area of awake, freely-behaving rats has also recently been studied [3]. In this last study, rats were trained to push down on a lever for > 1 second, and to pull back up to receive a water reward. The tuning properties of the neurons were studied by triggering on the pull-up of the lever, and neurons were classified according to the modulation of the firing rate relative to the pull-up trigger as pre-movement, movement, post-movement, hold-related, movement off, and non-related. It has been revealed that there is little difference between the tuning properties of cells in the various layers; all layers contain pretty much all tuning types, although the average firing rate of cells is higher in the deeper layers. Considering only the rate information, there does not seem to be much difference in the computations being carried out in the various layers. The local field potential (LFP) is thought to represent summed local synaptic currents, and as such, can be considered as containing information about the activity of the neural circuits, both cortical and extra-cortical. In this work, we pose the question whether there is really no laminar organization in the computations being carried out in the various layers of the forelimb area of M1. We analyzed the data presented in [3], obtained using the juxtacellular method of recording spikes from single, identifiable units in addition to multi-channel laminar LFP recordings from layers 1~6. Using this data, we analyzed the spike-LFP relationship using sliding, variable-width windows in which the LFP spike-triggered average (STA) was calculated for times between -1000 ms and 300 ms preceding and following the onset of a lever pull. The STAs were then assigned a z-score by comparing against an ensemble of STAs calculated using shuffled spike times (sSTA), effectively giving a number representing the significance of precise spike timing information. This was carried out for each of the 9 LFP channels, giving us a spatio-temporal plot of a given neuron’s relationship to the LFP. The resulting plots show a clear difference between L2/3 and L5/6 neurons. L2/3 neurons show fairly uniform and strong spike-LFP relationship throughout the analysis period, suggesting that these neurons are strongly locked to the underlying LFP regardless of the phase of movement. In contrast, cells in L5/6 often showed weaker spike-LFP relationship, and more modulation of strength throughout the analysis period, suggesting a more variable degree of spike precision to some underlying network activity.

The largest visual area, known as the primary visual cortex or V1, has greatly contributed to the current understanding of mammalian and human visual pathways and their role in visual perception. The initial discovery of orientation-sensitive neurons in V1, arranged according to a retinotopic mapping, suggested an analogy to its function as a low-level feature analyzer. Subsequent discoveries of phase, spatial frequency, color, ocular origin, and direction-of-motion-sensitive neurons, arranged into overlapping maps, further lent support to the view that it performs a rich decomposition, similar to signal processing transforms, of the retinal output. Like the other cortical areas, V1 has a laminar organization with specialization for input from the relayed retinal afferents, output to the higher visual areas, and the segregation of the magno (motion) and parvo (form) pathways. Spatially lateral connections that exist between neurons of similar and varying properties have also been proposed to give rise to a computation of a bottom-up saliency map in V1. We provide a review of the selectivity of neurons in V1, laminar specialization and analogies to signal processing techniques, a model of V1 saliency computation, and higher-area feedback that may mediate perception.

Sources of direct and indirect afferent connections of the caudate nucleus were investigated in cats by the retrograde axonal transport of horseradish peroxidase method. Different parts of the neocortex were shown to form different types of projections to the caudate nucleus; the sources of these projections have a laminar organization. Connections of the globus pallidus with the caudate nucleus, not previously described, were found. Among the sources of the thalamo-caudate projections, besides nuclei of the intralaminar complex, an important place is occupied by the ventral anterior and mediodorsal nuclei. After injection of horseradish peroxidase into the caudate nucleus, retrograde axonal transport of the enzyme was observed in the caudal direction, as far as cells of the locus coeruleus. ON the basis of these results a general scheme of afferent projections to the caudate nucleus is drawn up, including its connections with the spinal cord mediated by the thalamic nuclei and mesencephalic reticular formation.

Retinal inputs and their laminar distributions in the dorsal lateral geniculate nucleus (LGNd) of the eastern chipmunk (Tamias sibiricus asiaticus) were studied using histological and microelectrode recording techniques. A previous anatomical study (Fukuda et al. 1986a) indicated that the chipmunk LGNd had five laminae: contralaterally (contra) innervated lamina 1 and ipsilaterally (ipsi) innervated lamina 2 in its ventromedial part; laminae 3a (contra), 3b (ipsi) and 3c (contra) in its dorsolateral part. We have confirmed this finding in our present anatomical study and have also noted another ipsilaterally innervated thin lamina 0, medial to lamina 1. In our electrophysiological study, however, we were unable to record units from lamina 0 and to investigate it functionally. We recorded 232 units from laminae 1, 2 and the 3 complex, of which 95 were identified as Y-like, 46 as W-like, 15 as X-like, and 8 as mixed Y/W-like cells; the rest were either unclassified or visually unresponsive. In laminae 1 and 2, only Y-like and X-like cells were recorded, whereas in the laminae 3 complex W-like cells were recorded as well. The results suggest that the chipmunk laminae 1, 2 and 3 complex correspond relatively well to the cat laminae A, A1 and C complex, respectively. In the chipmunk LGNd, however, there were more Y-like cells in laminae 1 and 2, and a few X-like cells of which some were color sensitive. Also, lamina 3a had a concentration of mixed-type cells with Y-like receptive field properties and W-like OX latencies. As for retinotopy, the dorsoventral transition of the contralateral visual field (laminae 1, 3a, 3c) is represented along the dorsoventral dimension of the chipmunk LGNd, whereas the temporonasal transition is represented in the rostrocaudal direction. Receptive field positions of the ipsilaterally innervated relay cells are limited to the central overlapping field of the contralateral visual fields of both eyes. Relay cells with visual fields having elevations of below -20 degrees had relatively fast latency range and Y-like properties.

The location of labeled neurons that are sources of ascending crossed and uncrossed supraspinal fiber systems was studied in the laminae of gray matter of the spinal cord in 18 cats by the retrograde axonal transport of horseradish peroxidase method. Neurons in the lateral zones of the dorsal horn were shown to make direct, and cells in neighboring regions indirect (through relay nuclei of the dorsal columns) connections with the contralateral thalamus. In the lower segments of the spinal cord sources of crossed spinoreticular and spinothalamic fiber systems are located in the medial regions of the ventral horn and lateral zones of the lateral basilar region. Some large neurons in the motor nuclei were shown to send their axons into the lateral reticular nucleus of the medulla. On the basis of the results a scheme of the laminar organization of sources of ascending fiber systems in the cat spinal cord is constructed.

The Golgi technique has been used to examine the morphology of neurons within tectal transplants. Embryonic tectal tissue was transplanted to the midbrain of newborn rats. Four to eight months later, host animals were decapitated under anaesthesia, the unfixed brains removed and processed by Golgi-Cox impregnation. In tectal grafts, different types of neuron were recognized on the basis of the size and shape of their somata and the morphology of their dendritic trees. Neuronal types found in transplants resembled cell classes found in normal rat superior colliculus (SC). Neurons characteristic of the superficial collicular layers such as marginal, ganglion type I, stellate and horizontal cells and multipolar cells typical of the deeper collicular layers were identified in the transplants. Compared with normal cells, grafted neurons often had smaller dendritic fields and fewer dendritic spines. No laminar organization was discernable in the grafts and there was commonly no preferential orientation of perikarya or dendrites. Small cells with similar dendritic morphology were sometimes found grouped together in patches within the graft neuropil. These patches resembled cytologically and histochemically distinct areas described in previous studies and may represent areas homologous to the superficial layers of normal SC.

Dorsal root ganglion (DRG) neurones transmit cutaneous sensory information from the periphery to the spinal cord. Within the dorsal horn of the spinal cord, classes of sensory fibres that are activated by different cutaneous stimuli terminate in separate and highly restricted laminae1–3. Although the developmental events resulting in the laminar organization of sensory afferent terminals have not been defined, it is likely that interactions between surface molecules on DRG and dorsal horn neurones are involved in the generation of afferent synaptic connections. The identification of surface antigens that distinguish functional subclasses of DRG neurones would represent a first step in establishing the existence and nature of such molecules. We report here that monoclonal antibodies directed against carbohydrate differentiation antigens4,5 identify cytoplasmic and cell surface molecules expressed selectively by functional subsets of DRG neurones.

The responses of the interneurons of the thoracic segments of the spinal cord to stimulation of the intercostal and splanchnic nerves were studied on decerebrated and narcotized cats. It was established that the neurons of different layers of the gray matter (according to Rexed) differ substantially in type of afferent inputs. Cells in laminae I–III and IV are activated chiefly by somatic afferents: primarily high-threshold in laminae I–III and low-threshold in lamina IV. The neurons of lamina V and most of the neurons of laminae VII and VIII respond to stimulation of high-threshold somatic afferents (cutaneous fibers of the Aδ group and muscle afferents of groups II and III), as well as visceral afferents of group Aγδ, conducting impulses at a rate of 9–35 m/sec. Cells of laminae VII and VIII, monosynaptically activated by muscle afferents of group I, do not respond to stimulation of the visceral afferents. The peculiarities of the "functional" laminar organization of the thoracic segments of the spinal cord are discussed.

Cooling a culture of Chinese hamster cells to 21°C for 2 h reversibly blocks the cells in prometaphase. The stathmokinetic effect of cooling is connected with disappearance of the microtubules. The kinetochore in the blocked cells consists of a three-layered structure measuring 300–350 nm and 30–35 nm in thickness. Bundles of microtubules appeared in the dividing cells 10 min after warming, and at the same time the ultrasturcture of the kinetochore changed from a laminar organization into a spherical. These results confirm the view that the change from the laminar organization of the kinetochore into fibrillary-spherical is connected with its functional activation and is similar to the changes taking place in the kinetochore during the prometaphase of normal mitosis.