We analyzed the axonal projection of layer 2/3 (L2/3) interneurons with reference to geometric landmarks of cortical columns by staining neurons in acute slices of rat barrel cortex (P20-P29) and a subsequent cluster analysis using morphological parameters that described the spatial distribution of axons. 
The emergence of the whisker-related patterning of the barrel cortex during the first postnatal week is a frequently assessed feature of rodent cortical development and has been used extensively to screen for effects of genetic mutations on neural development in mice. As alterations in body weight often accompany genetic mutations, we asked whether body weight itself might affect the progression of barrel cortex development in wildtype C57/BL6 mice. We found that only 20% of the mouse pups had an established thalamocortical afferent pattern in the barrel cortex at P4 (4 out of 21 brains), while the majority of the pups showed a well-established pattern at P6 (13 of 16 brains). These findings may have implications for the interpretation of developmental changes in the barrel cortex of genetically modified mice..
Interneurons in layer 2/3 (L2/3) of the somatosensory cortex show 4 types of axonal projection patterns with reference to the laminae and borders of columns in rat barrel cortex (Helmstaedter et al.
Specifically, we observe a substantial deficit in local excitatory drive (~50%) targeting fast-spiking (FS) inhibitory neurons in layer 4 neurons of somatosensory, barrel cortex.
Using a rodent model of whisker-barrel cortex stroke, we have previously demonstrated that whisker activity promotes angiogenesis in the penumbra of the ischemic barrel cortex. This study explored the potential of increased peripheral activity to promote neurogenesis and neural progenitor migration toward the ischemic barrel cortex. Three days after focal barrel cortex ischemia in adult mice, whiskers were manually stimulated (15 min x 3 times/day) to enhance afferent signals to the ischemic barrel cortex.
We found that EDD in the mouse barrel cortex depends on the AMPA subunit GluR1 in layers II/III and IV, but not in layer V, and that long-term depression is also GluR1 dependent in the IV-II/III, but not II/III-V, pathway..
With that aim, electrophysiological recordings from the barrel cortex of anesthetized rats were obtained.
Recordings from B(a)P-exposed offspring revealed that N-methyl-d-aspartate (NMDA) receptor-dependent neuronal activity in barrel cortex evoked by whisker stimulation was also significantly reduced (70%) as compared to controls.
We recorded from pairs of L4 spiny neurons and L2/3 interneurons in acute slices of rat barrel cortex of postnatal day 20 (P20) to P29 rats.
The present study aims to investigate the developmental changes of miniature and unitary inhibitory postsynaptic currents (mIPSCs and uIPSCs) in mouse barrel cortex.
We investigated the ability of rat barrel cortex neurons to detect faint and transient whisker deflections occurring at unspecified times.
We performed full-band recordings from the barrel cortex of neonatal rats in vivo and found that the dominant pattern of the early activity, network driven spindle bursts, are associated with large amplitude NMDA receptor-dependent delta waves. The massive summation of thalamocortical activity during the spindle bursts thus provides a long time window for co-incident activation of cortical neurons by the thalamocortical cells which may contribute to the formation of thalamocortical synapses in the barrel cortex during the critical period of developmental plasticity..
Approximately half the excitatory neurons in layer 6 (L6) of the rat barrel cortex project to the thalamus with axon collaterals ramifying in the granular L4; the remaining project within cortex with collaterals restricted to infragranular laminae.
Here we show, using dual whole-cell recordings from layer 2/3 primary somatosensory barrel cortex in behaving mice, that the V(m) of nearby neurons is highly correlated during quiet wakefulness.
In the present study, we examined the organization of the vibrissae-barrel cortex in synRas mice and the effects of enhanced Ras activity on deprivation-induced dendritic reorganization after vibrissectomy. Partial vibrissectomy is followed by significant dendritic regression of corresponding pyramidal neurons in the barrel cortex of wild-type mice, which, however, could not be observed in synRas mice.
METHODS: Previous work from the same laboratory has demonstrated reorganization of whisker functional responses (WFRs) in the rat barrel cortex after excitotoxic lesions were created with kainic acid (KA).
Our findings underscore a mechanistic distinction between the termination of thalamocortical axonal plasticity in the barrel cortex and that in the visual cortex, in which OL-derived Nogo-A/B was recently suggested to be essential..
However, because AC1 is expressed throughout the trigeminal pathway, the barrel cortex phenotype of brl mice may be a consequence of AC1 disruption in cortical or subcortical regions. These results suggest that activity-dependent postsynaptic AC1-cAMP signaling is required for functional maturation of TC synapses and the development of normal barrel cortex cytoarchitecture. They also suggest that the formation of the gross morphological features of barrels is independent of postsynaptic AC1 in the barrel cortex..
By loading MK-801 into pre- or postsynaptic neurons during paired recordings of synaptically connected layer 4 and layer 2/3 neurons in mouse barrel cortex, we found that synaptic potentiation requires postsynaptic, but not presynaptic, NMDA receptors, whereas synaptic depression requires presynaptic, but not postsynaptic, NMDA receptors..
We therefore examined the cell-type specificity and functional significance of tonic inhibition in layer 4 of the mouse somatosensory barrel cortex.
Under baseline conditions, new spines in the barrel cortex were mostly transient and rarely survived for more than a week.
The thalamocortical projection to the rodent barrel cortex consists of inputs from the ventral posterior medial (VPM) and posterior medial (POm) nuclei that terminate in largely nonoverlapping territories in and outside of layer IV. Here, using transport of Phaseolus vulgaris leucoagglutinin(PHA-L) or carbocyanine dyes, we characterize the POm thalamocortical innervation of adult mouse barrel cortex and describe its early postnatal development in both mice and rats. Developmentally, in both species, POm axons are present in barrel cortex at birth. Taken together, these data reveal anatomical differences between mice and rats in the development and organization of POm inputs to barrel cortex, with implications for species differences in the nature and plasticity of lemniscal and paralemniscal information processing..
In the barrel cortex of rodents, cells respond to a principal whisker (PW) and more weakly to several adjacent whiskers (AWs). The results reveal that simultaneous and temporally dispersed wide-field sensory inputs are discriminated at the level of single cells in barrel cortex with high temporal resolution, but the ability to compute this difference is highly dynamic and dependent on the level of adaptation in the thalamocortical network..
To address this discrepancy, multiunit and single-unit recordings were performed in the barrel cortex of isoflurane-anesthetized rats using continuous sinusoidal vibration of single whiskers at 15-700 Hz.
Immunohistochemical and electrophysiological experiments were undertaken to determine the coupling properties of astrocyte networks in layer IV of the developing barrel cortex. The shape of dye coupling was oval in the barrel cortex whereas it was circular in layer IV outside the barrel field.
Here, we investigated the development of excitatory projections in the barrel cortex of Fmr1 ko mice.
We show that FS cells in layer 2/3 barrel cortex possess a dampening mechanism mediated by Kv1.1-containing potassium channels localized to the axon initial segment.
Optical imaging spectroscopy, laser Doppler flowmetry and electrophysiology were used to measure haemodynamics and neural activity in the barrel cortex of anaesthetized rats.
A previous study (Ding et al., 2003) showed that the homeodomain transcription factor DRG11 is necessary for pattern formation in the trigeminal nucleus principalis (PrV), the requisite brainstem nucleus for development of the whisker-to-barrel cortex pathway.
The columnar organization is most apparent in the whisker barrel cortex but seems less apparent in the gustatory insular cortex. In contrast to the well known excitation spread in the horizontal direction in layer II/III induced in the barrel cortex by layer IV stimulation, the excitation caused in the insular cortex by stimulation of layer IV spread bidirectionally in the vertical direction into layers II/III and V/VI, displaying a columnar image pattern. Bicuculline or picrotoxin markedly extended the horizontal excitation spread in layer II/III in the barrel cortex, leading to a generation of excitation in the underlying layer V/VI, whereas those markedly increased the amplitude of optical responses throughout the whole column in the insular cortex, subsequently widening the columnar image pattern. Thus, a unique functional column existed in the insular cortex, in which intracolumnar communication between the superficial and deep layers was prominent, and GABA(A) action is involved in the inhibition of the intracolumnar communication in contrast to its involvement in intercolumnar lateral inhibition in the barrel cortex.
To better understand the basis for VB and cortical abnormalities, we used small placements of DiI to trace axonal projections between BSTC, VB, and barrel cortex in wildtype (WT) and GAP-43 KO mice.
We found that non-postsynaptic, likely presynaptic NR2B-containing NMDARs enhanced AMPA receptor-mediated synaptic transmission at layer 4 (L4) to L2/3 (L4-L2/3) synapses in juvenile rat barrel cortex.
We test the feasibility of these methods on synthetic data, and on responses from a neuron in rodent barrel cortex.
Electrophysiological and neuroanatomical analyses revealed also that LD projects upon the cingulate and retrosplenial cortex, but has only sparse projections to the barrel cortex.
The rodent barrel cortex is a useful system to study the role of genes and neuronal activity in the patterning of the nervous system.
In the vibrissa-to-barrel cortex system, these include the lemniscal system and the lesser-known paralemniscal system.
Our results suggest that chronic morphine exposure has a subtle modulatory effect on response properties of neurons in barrel cortex..
barrel cortex neuronal responses adapt to changes in the statistics of complex whisker stimuli. In other systems, adaptation and gain rescaling can depend on intrinsic properties; however, in barrel cortex, whether intrinsic mechanisms can contribute to adaptation to stimulus statistics is unknown. Our results suggest that widely expressed intrinsic mechanisms participate in barrel cortex adaptation but that their recruitment is highly stimulus specific..
We studied circuit activities in layer IV of rat somatosensory barrel cortex containing microgyri induced by neonatal freeze lesions. Similar stimuli in TC slices from lesioned barrel cortex elicited prolonged 850 +/-100 ms paroxysmal discharges that originated in the PMG and propagated laterally over several mm.
In mice, we examined the effect of ongoing whisker stimulation on synaptic strengthening at layer 4-2/3 synapses in the barrel cortex.
In this study, a systematic method was established based on whisker pairing (WP) experiment to measure the network plasticity in the barrel cortex in rat. WP experiment is a classical experiment to study the effect of innocuous bias of the flow of sensory activity from the whiskers for certain periods in awake and behaving rats on the receptive field organization in S1 barrel cortex neurons.
We trained rats to respond to microstimulation of barrel cortex at low current intensities.
Single brief whisker deflections evoked highly distributed depolarizing cortical sensory responses, which began in the primary somatosensory barrel cortex and subsequently excited the whisker motor cortex.
Here, we characterized single-neuron and population responses to whisker stimulation in layer 2/3 (L2/3) of identified columns in rat barrel cortex using in vivo two-photon calcium imaging.
The objective of the present study was to build a dynamic model relating changes in neural responses in rat barrel cortex to an electrical whisker stimulation pulse train of varying frequencies.
We recorded neuronal activity from barrel cortex while rats used their whiskers to discriminate between rough and smooth textures. In conclusion, these data suggest that barrel cortex firing rate on each trial leads directly to the animal's judgment of texture..
Rodent somatosensory barrel cortex is organized both physiologically and anatomically in columns with a cross-sectional diameter of 100-400 microm.
To investigate whether synaptic properties between neocortical pyramidal neurons change during the assembly period of cortical circuits, whole-cell voltage recordings were made simultaneously from two layer 5A (L5A) pyramidal neurons within the cortical columns of rat barrel cortex.
We report a step in constructing an in silico model of a neocortical column, focusing on the synaptic connection between layer 4 (L4) spiny neurons and L2/3 pyramidal cells in rat barrel cortex.
Fos-immunoreactivity induced by acute apomorphine administration (barrel cortex, paraventricular hypothalamic nucleus, central amygdala and locus coeruleus) was strongly reduced after chronic administration.
Results indicated that only arterioles overlying the stimulated hindlimb cortex showed a significant increase of total power, unlike arterioles overlaying the whisker barrel cortex, used as control for the vascular response specificity.
In the neocortex and in particular the barrel cortex, numerous neuronal connections within or between cortical layers have been studied both at the functional and structural level.
We aim to clarify in a rodent model how intra- and transcolumnar microcircuits in the barrel cortex are laid out to segregate and also integrate sensory information.
These experiments compared the responses of neurons in rat barrel cortex with trains of whisker movements with different frequencies; each train possessed either a periodic or an irregular, "noisy" temporal structure.
We find that demethylation of neurons in the cerebral cortex results in the failure of development of somatosensory barrel cortex.
Separate afferent pathways convey somatosensory information to the barrels and septa that represent the input stages for 2 partially segregated circuits that extend throughout the other layers of barrel cortex. The projection patterns from barrel cortex indicate that information processed by the septa-related circuits is used both separately and in combination with information from the barrel-related circuits to mediate specific functions.
Neural networks of the rodent barrel cortex are particularly tractable for developing a quantitative understanding of response transformations in a cortical column. A column in barrel cortex consists of approximately 10 compartments.
The available data suggest that sensory experience can modulate temporal aspects of response integration and receptive field properties of layers IV and V neurons in barrel cortex.
The significance of such a code may be that it enables a small number of neurons, firing only few spikes, to convey distinctions between very many different textures to the barrel cortex..
This was further tested in rat barrel cortex, where a sensory activated synaptic potential was also larger in up states.
Here, we used bulk loading of Ca(2+) indicators combined with two-photon microscopy to image the activity of multiple single neurons in layer (L) 2/3 of the mouse barrel cortex in vivo.
This study therefore sought to determine the effect of ageing on NMDA-stimulated Ca(2+) uptake into barrel cortex slices of Spontaneously Hypertensive Rats (SHR) compared to control Wistar-Kyoto rats (WKY). It can be concluded that ageing negatively affects NMDA-stimulated Ca(2+) uptake into barrel cortex slices of SHR and WKY..
Field excitatory postsynaptic potentials (EPSPs) from GAP-43 -/- thalamocortical synapses reveal a reduced fiber response, and anatomical analysis shows reduced thalamic innervation of barrel cortex in GAP-43 -/- mice.
Here, we investigated whether PNs in the mouse barrel cortex are expressed in an activity-dependent manner by manipulating sensory input through whisker trimming. Importantly, this manipulation did not lead to a global loss of PNs but instead led to a specific decrease in PNs, detected with the antibody Cat-315, in layer IV of the barrel cortex.
The current study shows that despite these abnormal periods of whisker deprivation, the barrel cortex of nude mice develops a normal structural appearance viewed with cytochrome oxidase staining. Additionally, intrinsic optical imaging studies of barrel cortex responses to single whisker stimulation do not appear altered from normal despite periodic loss of adjacent whiskers..
Here we studied if the inability of barrel cortex to produce approximately 10 Hz oscillations during these conditions is because barrel cortex networks lack the necessary cellular mechanisms or, alternatively, because those mechanisms are inhibited by outward currents. The results show that blockers of slowly inactivating voltage-dependent K+ currents unmask approximately 10 Hz oscillations in barrel cortex, and this occurs in unison with the unmasking of intrinsic inward Ca++ currents that are kept suppressed by the outward currents. Moreover, the approximately 10 Hz oscillations unmasked in barrel cortex occur independently in upper and lower layers indicating that the approximately 10 Hz oscillation mechanisms are kept suppressed in multiple networks.
Generally, barrel cortex neurones were responsive to a much wider range of whisker protraction velocities than hitherto reported, especially to much slower velocities than generally assumed to be the main range of sensitivity.
We trained head-restraint rats to indicate the detection of cortical microstimulation in infragranular layers of barrel cortex.
These data show that ipsilateral whiskers can constrain receptive field size in the barrel cortex..
We combined these two imaging techniques using epifluorescence optics together with whole cell recordings to measure the spatiotemporal dynamics of activity in the mouse somatosensory barrel cortex in vitro and in the supragranular layers in vivo.
Here we show that the GABAA receptor-mediated conductance is depolarizing in excitatory (stellate) cells in neonatal (postnatal day [ P]3-5) layer IV barrel cortex, but GABAergic transmission at this age is not engaged by thalamocortical input in the feedforward circuit and has no detectable circuit function.
Previous experiments demonstrated that (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid (1S,3R-ACPD) depressed excitatory transmission in the adult rat barrel cortex.
Here, we report that BDNF plays an essential role in the normal development of PV-FS cells during a plastic period in the barrel cortex.
We therefore juxtasomally recorded action potential (AP) patterns from excitatory cells in layer (L) 2/3, L4, L5 and L6 of rat barrel cortex in response to a standard stimulus (e.g.
In the rodent somatosensory system, stimulus information received by the whiskers is relayed to the barrel cortex via two parallel pathways, the lemniscal pathway and the paralemniscal pathway.
In rats with infarct posterior to the barrel cortex, no plastic change of the spared row representation was observed.
In the present study we examined the distribution and expression levels of these two VGLUTs during postnatal development of the mouse barrel cortex. Furthermore, we found that some nerve terminals in the barrel cortex coexpressed both transporters until adulthood.
The sensory responses in the barrel cortex of mice aged postnatal day (P)7-P12 evoked by a single whisker deflection are smaller in amplitude and spread over a smaller area than those measured in P13-P21 mice.
Whisker deflection is an effective conditioned stimulus (CS) for trace eyeblink conditioning that has been shown to induce a learning-specific expansion of whisker-related cortical barrels, suggesting that memory storage for an aspect of the trace association resides in barrel cortex. To examine the role of the barrel cortex in acquisition and retrieval of trace eyeblink associations, the barrel cortex was lesioned either prior to (acquisition group) or following (retention group) trace conditioning. The acquisition lesion group was unable to acquire the trace conditioned response, suggesting that the whisker barrel cortex is vital for learning trace eyeblink conditioning with whisker deflection as the CS. The retention lesion group exhibited a significant reduction in expression of the previously acquired conditioned response, suggesting that an aspect of the trace association may reside in barrel cortex. These results demonstrate that the barrel cortex is important for both acquisition and retention of whisker trace eyeblink conditioning. Furthermore, these results, along with prior anatomical whisker barrel analyses suggest that the barrel cortex is a site for long-term storage of whisker trace eyeblink associations..
High-frequency stimulation of barrel cortex afferents to the vibrissal motor cortex mimicked CS-related potentials growth, suggesting that the latter process was due to a learning-dependent potentiation of cortico-cortical synaptic inputs.
We searched for motifs in spontaneous activity, recorded from the rat barrel cortex and from the cat striate cortex of anesthetized animals, and found numerous repeating patterns of high similarity and repetition rates.
Here we examine how adaptation affects sensory coding in barrel cortex. Therefore, in barrel cortex, rate adaptation occurs on a slow timescale relative to the features driving spikes and is associated with gain rescaling matched to the stimulus distribution.
Supragranular activities in the barrel cortex were clearly suppressed. Furthermore, activities elicited in the rostral small vibrissae/mouth area of S1 near the border between S1 and S2 spread into the adjacent barrel cortex rather than into S2.
Several excellent reviews have been published on the patterning and plasticity of the barrel cortex and the precise targeting of ventrobasal thalamic axons.
Careful experimental set up ensured that both techniques recorded from spatially concordant regions of the barrel cortex, where functional responses were maximal.
The method is applied to stimulus-averaged laminar-electrode data from barrel cortex of anesthetized rat after single whisker flicks.
Neurons in the barrel cortex and the thalamus respond preferentially to stimulation of one whisker (the principal whisker) and weakly to several adjacent whiskers.
Some recent data on both topics in the rodent barrel cortex will be presented in this topical review..
To investigate mechanisms of this compensatory plasticity we followed changes in the brain's pattern of activation evoked by stimulation of vibrissae, after a focal cortical stroke which destroyed the cortical representation of vibrissae, the barrel cortex. In control rats this stimulation activates the barrel cortex and the second somatosensory cortex in the contralateral hemisphere. Seven days after stroke in the barrel cortex, significant increases in activation were found in ipsilateral, uninjured hemisphere in the barrel cortex and anterior vibrissae representation, and also in regions not specifically connected to vibrissae stimulation, such as motor and auditory cortex.
Neural responses were recorded extracellularly in barrel cortex while single whiskers were deflected with 0.5-18 air puffs per second (apps), a range that includes the whisk rates observed when rats explore their environment and discriminate surfaces with their whiskers.
We used quantitative laser scanning photostimulation to probe the organization of functional thalamocortical and ascending intracortical projections in the mouse barrel cortex. Paralemniscal L5A neurons targeted a superficial band (thickness, 60 mum) of neurons immediately below L1, defining a functionally distinct L2 in the mouse barrel cortex.
Here, we studied network mechanisms of generation of spindle-bursts in the barrel cortex of neonatal rats using a superfused cortex preparation in vivo. Both spontaneous and sensory-evoked spindle-bursts were present in the superfused barrel cortex. We propose that local spindle-burst oscillations, driven by glutamatergic synapses and spatially confined by GABAergic synapses, contribute to the development of barrel cortex during the critical period of developmental plasticity..
Using two-photon microscopy, we imaged PSD-95 tagged with GFP in layer 2/3 dendrites in the developing (postnatal day 10-21) barrel cortex.
Using mice, we found that 24 h of whisker stimulation elicited a 2-fold increase in the expression of GLT1 and GLAST in the corresponding cortical column of the barrel cortex.
Under asynchronous brain activity, many FSs (>60%) elicited small-amplitude mu-rhythm-like activity in the barrel cortex concomitant with FS-related rhythms in the occipital cortex and resulted in significant augmentation of 7-12 Hz power in the parietal region.
We reconstructed individual biocytin-injected TCAs from thalamus to barrel cortex in NOR (normal) and BRL mice to analyze to what extent the TCA arborization pattern and bouton distribution could explain the topographic representation of the whisker follicles.
During the first pairing session, an increased 2DG uptake was seen in the barrel cortex of both hemispheres, independently of the type of applied unconditioned stimulus. In the third session of the sensory pairing, activation of the barrel cortex was solely contralateral, as expected after unilateral whisker stimulation.
Labeled projections from the contralateral SI barrel cortex, however, were much fewer in number and were disproportionately associated with the septal compartments.
This work explores how neurons at two levels of the sensory pathway, trigeminal ganglion and barrel cortex, carry information about such stimuli.
In rat barrel cortex, layer 4 has a transiently high density of zinc-positive terminations from postnatal day (P)9 to P12 [ P.W. To determine their sources, we injected sodium selenite into the barrel cortex of two adult rats and 32 pups, from P5 to P28.
The magnitude of barrel cortex evoked responses was measured in response to stimulation of the cut and paired whiskers of rats under several conditions: (a) whisking in air (control), (b) active whisking of an object by the rat, and (c) epochs of passive whisker stimulation to identify the onset of whisker pairing plasticity changes in cortex. The results support the conclusion that whisker pairing plasticity in barrel cortex occurs within 4 h after whisker trimming in an awake, alert animal..
We used short interfering RNA (siRNA)-based knockdown of Na+ channels to suppress the somatodendritic excitability of small numbers of layer 2/3 pyramidal neurons in the barrel cortex, without altering the ascending sensory pathway.
We have previously shown that projections from SI barrel cortex to the MI whisker representation originate primarily from columns of neurons that are aligned with the layer IV septa. SI barrel cortex also projects to SII cortex, but the origin of these projections has not been characterized with respect to the barrel and septal compartments. We found that the projections to SII cortex originate from sites that are uniformly distributed throughout the extragranular layers of barrel cortex.
We imaged dendrites in barrel cortex of adult mice over 1 month, tracking gains and losses of spines.
In barrel cortex NMDA receptor (NMDAR)-dependent long-term potentiation (LTP) and long-term depression (LTD) play a critical role in the development and experience-dependent plasticity of the topographical map of the rodent whiskers. Here we investigate the role of PKC in the regulation of synaptic strength in neonatal barrel cortex using patch-clamp recordings in brain slices. These findings demonstrate that PKC is required for the regulation of transmission at thalamocortical synapses, the major ascending sensory input to barrel cortex. Thalamocortical inputs in barrel cortex only express LTP during the first postnatal week during a critical period for experience-dependent plasticity in layer IV. Therefore, the requirement for PKC in LTP suggests an important role for this kinase in the development of the barrel cortex sensory map..
The somatosensory barrel cortex of rodents and its afferent pathway from the facial vibrissae is a very useful model for studying neuronal plasticity.
Spontaneous activity was reduced by approximately 50% in barrel cortex compared to corn oil vehicle controls.
In this study, we investigated the mechanisms underlying synaptic plasticity at the layer IV to II/III pathway in barrel cortex of mice aged 6-13 weeks. This pathway is one of the likely candidates for expression of experience-dependent plasticity in the barrel cortex and may serve as a model for other IV to II/III synapses in the neocortex.
This was demonstrated by labeling with 2-deoxyglucose (2DG) in layer IV of the barrel cortex. Unbiased optical disector counting was applied to sections from the mouse barrel cortex that had been immunostained using a polyclonal antibody against GAD67.
However, the deprived barrel cortex displayed an increase in SV in layers I and II, and an increase in NA in layer I and in the cortex as a whole, mainly due to an increase in profiles with a convex shape.
In the apical tufts of layer 5B (L5B) pyramidal neurons in the mouse barrel cortex, a subset of dendritic spines appear and disappear over days, whereas most spines are persistent for months.
Under alpha-chloralose anesthesia, barrel cortex exhibits strong quasi-periodic approximately 1-Hz local field potential (LFP) oscillations generated by the synchronized fluctuation of large populations of neurons between depolarized (Up) and hyperpolarized (Down) states.
Evoked field potential responses were recorded using electrodes implanted into the contralateral barrel cortex.
We used a flexible fiber optic image bundle to visualize voltage-sensitive dye dynamics in the barrel cortex of freely moving mice while simultaneously filming whisker-related behavior to generate two movies matched frame-by-frame with a temporal resolution of up to 2 ms. Sensory responses evoked by passive whisker stimulation lasted longer and spread further across the barrel cortex in awake mice compared to anesthetized mice.
Here we show that whisker stimulation evokes increases in astrocytic cytosolic calcium (Ca(2+)) within the barrel cortex of adult mice.
In two of these lines, named X94 and X98, GFP expression in the barrel cortex was restricted to subsets of somatostatin-containing (SOM+) GABAergic interneurons, similar to the previously reported "GIN" line (Oliva et al., 2000), but the laminar distributions of GFP-expressing (GFP+) cell bodies in the X94, X98, and GIN lines were distinct and nearly complementary.
In the present study of whisker-barrel cortex ischemia in the mouse model, we tested the hypothesis that enhancing whisker activity and sensory input to the ischemic barrel cortex might promote post-ischemia cerebral angiogenesis. Three days after focal ischemia in adult mice, the whiskers corresponding to the ischemic barrel cortex were stimulated by two methods: (1) whiskers on the right side of the mouse face were trimmed away, so the left whiskers were overused by the animals, (2) left whiskers were manually stimulated to enhance input signals to the ischemic barrel cortex.
We examined the spatial structure of noise in optical recordings made with two commonly used voltage-sensitive dyes (RH795 and RH1691) in mouse barrel cortex in vivo, and determined that the signal-to-noise ratio of the two dyes was comparable when averaging over barrel-sized areas, or at single pixels distant from large blood vessels.
We demonstrate that brain activity evoked during whisker stimulation can be detected with hyperspectral interferometric microscopy to identify the active whisker-barrel cortex in the rat brain.
We localize PKARIIbeta function to postsynaptic processes in barrel cortex and show that postsynaptic PKA targets, but not presynaptic PKA targets, have decreased phosphorylation in pkar2b knock-out (PKARIIbeta(-/-)) mice.
In the barrel cortex, encoding of information requires a high-precision temporal code with a resolution of approximately 5 ms; however, it is not known what process drives the maturation in timing precision. Here, we report that long-term potentiation (LTP) at thalamocortical synapses in the neonatal layer IV barrel cortex produces a dramatic improvement in the timing of neuronal output and synaptic input. Therefore, neonatal thalamocortical LTP may be a critical prerequisite for the maturation of information processing in the barrel cortex..
To investigate synaptic events underlying sensory perception, we made whole-cell membrane potential recordings of barrel cortex neurons in awake mice while recording whisker-related behavior.
Science 265(5180):1885-1888] and continues until a new stable state is achieved [ Experience-dependent plasticity in adult rat barrel cortex. Proc Natl Acad Sci U S A 90(5):2082-2086; Armstrong-James M, Diamond ME, Ebner FF (1994) An innocuous bias in whisker use in adult rat modifies receptive fields of barrel cortex neurons.
We imaged axons in layer (L) 1 of the mouse barrel cortex in vivo.
Our results suggest a modulating role for DRN in processing of the incoming information into barrel cortex.
Inhibitory and excitatory neurons located in rodent barrel cortex are known to form functional circuits mediating vibrissal sensation.
A transient expression of zinc is reported in at least one other cortical area (layer IV of barrel cortex from postnatal day 5 to postnatal day 14, maximal at postnatal days 9-11).
To determine whether PAE alters the central representation of the forelimb we used the rodent barrel cortex as our model system where it was possible to visualize and quantitatively measure the size of the forepaw representation in the forepaw barrel subfield (FBS) in first somatosensory cortex.
We have previously reported that a classical conditioning paradigm involving stimulation of a row of facial vibrissae produced expansion of the cortical representation of the activated vibrissae ("trained row"), this was demonstrated by labeling with 2-deoxyglucose in layer IV of the barrel cortex. parvalbumin negative) of GABAergic interneurons is involved in learning-dependent changes in layer IV of the barrel cortex..
We studied NMDAR-mediated miniature EPSCs (mEPSCs) and NMDA channel currents in tangential brain slices of mouse barrel cortex, which exclusively contain layer 4.
In layer 4 (L4) of the rat barrel cortex, a single whisker deflection evokes a stereotyped sequence of excitation followed by inhibition, hypothesized to result in a narrow temporal window for spike output.
Postnatal day 7 rats were subjected to permanent occlusion of the middle cerebral artery branch supplying the right whisker-barrel cortex.
Most notably, there were differences in local input to neurons that, based on analogy to barrel cortex, are likely to project only to the lateral geniculate nucleus of the thalamus versus those that are likely to also project to the lateral posterior nucleus.
We used cross-correlation analysis to characterize the incidence and strength of stimulus-induced neuronal synchronization in different layers of SI barrel cortex and as a function of neuronal location in different barrel columns. Finally, we compared the present results with synchronized responses in somatosensory (SI) barrel cortex that were evoked by controlled, pulsatile whisker movements in a previous study.
This suggests that intraneuronal Nogo-A may play roles in neurite growth and axonal regeneration of the corticofugal neurons, but not of columnar intrinsic neurons, in layer V of the S1 barrel cortex. Additionally, this study demonstrates a novel result, which is that layer V pyramidal neurons of the S1 barrel cortex exhibit a pattern of cell size-dependent intraneuronal Nogo-A expression..
Here, we show that in the rodent barrel cortex, the temporal window for integration of thalamic inputs is under the control of thalamocortical feed-forward inhibition and can vary from 1 to 10 ms.
In the rat barrel cortex, neurons in layer 4 are topographically arranged in a precise columnar structure, and the excitatory feed-forward input from layer 4 to layer 2/3 projects almost exclusively within the home barrel column. We examined the spatial distributions of three different functional types of lateral connections in layer 2/3 of the rat barrel cortex: glutamate receptor-mediated excitatory connections, GABA(A) receptor-mediated inhibitory connections and GABA(B) receptor-mediated inhibitory connections.
Multielectrode extracellular recordings in deep layers of barrel cortex revealed that when the animals moved their whiskers actively, tactile processing switched from high response amplitudes, wide cortical representation and low background firing, to low response amplitudes, narrow spatial representation and elevated background firing.
In this study we perform two-dimensional optical imaging spectroscopy (2D-OIS) in rat barrel cortex during contralateral whisker stimulation to obtain two-dimensional maps over time of Hbr, HbO2 and Hbt.
This study was done to determine if the intrinsic cortical connectivity pattern of the barrel cortex, established during the critical period, affects the process of representational plasticity that follows whisker follicle ablation.
Here we use in vivo intracellular recordings from thalamorecipient neurons in layers 3 and 4 of the rat barrel cortex to elucidate the dynamics of the synaptic inputs underlying direction selectivity.
Excitation survives barrel cortex lesion, demonstrating its peripheral origin.
We investigated the relationship between these hemodynamic parameters in the rodent barrel cortex by performing fMRI concurrently with laser Doppler flowmetry (LDF) or optical imaging spectroscopy (OIS), following whisker stimulation and hypercapnic challenge.
Previously, we have shown that whisker plucking, a manipulation commonly used to induce cortical map plasticity, results in a rapid and robust increase in staining levels for synaptic zinc in deprived regions of the barrel cortex. In the present study, we examined the effect of increased whisker activity, analogous to what may happen during tactile learning or exploratory behavior in a natural setting, on synaptic zinc levels in the adult barrel cortex.
Here we used transcranial two-photon microscopy to visualize postsynaptic dendritic spines in layer I of the barrel cortex in transgenic mice expressing yellow fluorescent protein.
Unilateral ablation lesions of barrel field cortex (BFC) in adult rats induce strong suppression of background and evoked activity in the contralateral barrel cortex and significantly delay the onset of experience-dependent plasticity.
Using in situ hybridization, we monitored cpg15 expression in 4-week-old mouse barrel cortex after trimming all whiskers except D1.
We now extend those findings to the investigation of the role of neurotrophin signaling in barrel cortex formation. These results indicate that TrkB expression in thalamic axons is important for the appropriate timing of barrel cortex development..
In the present study, laser speckle imaging (LSI) was employed to measure stimulus-evoked neuronal activities in rat barrel cortex.
The present study focused on the relationship between synaptic zinc and zinc transporter 3 (ZnT3) protein expression in the barrel cortex of mice during postnatal development and after sensory deprivation of selected vibrissae. These results suggest that in the barrel cortex ZnT3, synapsin I or synaptophysin are not determinant for the activity-dependent regulation of the synaptic zinc level..
The response to whisker stimulation in rodent barrel cortex was recorded during baseline (normocapnia) and elevated perfusion rates produced by two levels of hypercapnia (5 and 10%).
These results suggest that the GABAA-mediated inhibition that modulates the receptive field functional organization of the barrel cortex depends on intact C-fibers..
Cells in the rat barrel cortex exhibit stimulus-specific response properties.
From these results, it can be inferred that asymmetric intrinsic structural connections are reflected in the functional metabolic barrel representation under the condition of neural plasticity in the barrel cortex following whisker deafferentation..
Using the same paradigm, the present study examined field potentials evoked in ex vivo slices of the barrel cortex.
Excitatory synaptic projections to layer 2/3 (L2/3) pyramidal neurons in brain slices from the rat barrel cortex were measured using quantitative laser-scanning photostimulation (LSPS) mapping. In the barrel cortex, cytoarchitectonic "barrels" and "septa" in L4 define a stereotypical array of landmarks, allowing alignment and averaging of LSPS maps from multiple cells in different slices. These projections are likely to mediate parallel processing of somatosensory signals within the barrel cortex, with L4-->2/3barrel and L5A-->2septum representing the intracortical continuations of, respectively, the subcortical lemniscal and paralemniscal systems conveying somatosensory information to the barrel cortex..
During the first week of life, there is a shift from kainate to AMPA receptor-mediated thalamocortical transmission in layer IV barrel cortex.
Therefore, in each animal, we injected two anterograde tracers into SI barrel cortex and compared the relative density and spatial extent of the labeled projections to the primary motor (MI) cortex, neostriatum, superior colliculus, and basal pons. These results are consistent with physiological evidence indicating strong coherence between SI barrel cortex and the cerebellum during whisking behavior..
Cerebral blood volume functional magnetic resonance imaging (CBV-fMRI) experiments employing iron oxide contrast agent were conducted in rat whisker barrel cortex at 3 Tesla.
In the present study, using the same experimental model, we examined GAD65 mRNA and protein levels in the barrel cortex.
Can neuronal morphology predict functional synaptic circuits? In the rat barrel cortex, 'barrels' and 'septa' delineate an orderly matrix of cortical columns.
For this we combined detailed electrophysiological and morphological characterization with mapping of intracortical functional connectivity by caged glutamate photolysis in layer Va of rat barrel cortex in vitro.
Tracing experiments revealed that the deafferented cortex did not receive a novel thalamic input but that cortico-cortical and contralateral barrel cortex projections to this area were reinforced.
Over 18 months, only 26% of spines were eliminated and 19% formed in adult barrel cortex.
We analyze information derived from direct stimulation experiments in slices from rat barrel cortex and construct a computational model of a layer V pyramidal neuron that reproduces the experimental findings.
The effect of transplantation of adult bone marrow stromal cells (MSCs) into the freeze-lesioned left barrel field cortex in the rat was investigated by measurement of local cerebral glucose utilization (lCMR(glc)) in the anatomic structures of the whisker-to-barrel cortex sensory pathway. Local cerebral glucose utilization measurements showed that the freezing cortical lesion did not alter the metabolic responses to stimulation in the brain stem trigeminal nuclei, but eliminated the responses in the left VPM nucleus and periphery of the barrel cortex in the PBS-treated group. The left/right (stimulated/unstimulated) lCMR(glc) ratios were significantly improved in both the VPM nucleus and periphery of the barrel cortex in the MSC-treated group compared with the PBS-treated group (P<0.05).
The barrel cortex of rodents is densely innervated by a prominent subclass of glutamatergic neurons that sequester and release zinc from their synaptic boutons. These neurons may play an important role in barrel cortex function and plasticity, as zinc has been shown to modulate synaptic function by regulating neurotransmitter release, excitatory and inhibitory amino acid receptors, and second messenger signaling cascades. Here, we utilized intracortical infusions of sodium selenite to identify the source of the zincergic innervation to the mouse barrel cortex. Our results demonstrate that the majority of zincergic projections to the barrel cortex arose from ipsilateral and callosal neurons, situated in cortical layers 2/3 and 6. Regionally, these labeled neurons were most abundant within the barrel cortex itself, posterior parietal association cortex, secondary somatosensory cortex, and motor cortex. Further, some mice were injected with the retrograde tracer cholera toxin subunit B to compare retrograde labeling of zincergic neurons with that of the general population of neurons innervating the barrel cortex. Our data indicate that all cortical regions providing inputs to the barrel cortex possess a zincergic component, whereas those from thalamic or brainstem structures do not. These findings demonstrate that zincergic pathways comprise a chemospecific associational network that reciprocally interconnects the barrel cortex with other cortical and limbic structures..
lCMR(glc) was increased by stimulation but to a markedly lesser extent in 5-HTT(-/-) mice than in 5-HTT(+/+) controls in each of four major stations in the whisker-to-barrel cortex pathway (the spinal and principal sensory trigeminal nuclei, the ventral posteromedial thalamic nucleus, and the barrel region of the somatosensory cortex). Lowering brain 5-HT levels by administration of the selective tryptophan hydroxylase inhibitor p-chlorophenylalanine on postnatal days 0 and 1 restored the metabolic responses to functional activation in the whisker-to-barrel cortex pathway in adult 5-HTT(-/-) mice. With or without postnatal p-chlorophenylalanine treatment, 5-HTT(-/-) mice exhibited lower resting (unstimulated) lCMR(glc) than did 5-HTT(+/+) controls in the whisker-to-barrel cortex pathway and throughout the brain.
To determine the role of postsynaptic NMDARs in presynaptic afferent development and patterning in the barrel cortex, we examined the single TCA arbors in CxNR1KO mice between postnatal days (P) 1-7. Given that thalamic NMDARs are spared in CxNR1KO mice, the present results show that postsynaptic NMDARs play an important role in refinement of presynaptic afferent arbors and whisker-specific patterning in the developing barrel cortex..
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