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. We di...

Cortical neurons are organized in columns, distinguishable by their physiological properties and input-output organization. Columns are thought to be the fundamental information-processing modules of the cortex. The barrel cortex of rats and mice is an attractive model system for the study of cortical columns, because each column is defined by a layer 4 (L4) structure called a barrel, which can...

Upregulation of brain-derived neurotrophic factor (BDNF) mRNA expression by neuronal activity has been reported in cultured hippocampal cells and in different in vivo excitotoxic paradigms. The aim of the present study was to determine whether sensory stimulation of the whisker-to-barrel pathway alters BDNF mRNA expression in the cortex and, if so, to evaluate the specificity of this effect. To...

The current study investigates a new model of barrel cortex activation using stimulation of the infraorbital branch of the trigeminal nerve. A robust and reproducible activation of the rat barrel cortex was obtained following trigeminal nerve stimulation. Blood oxygen level-dependent (BOLD) effects were obtained in the primary somatosensory barrel cortex (S1BF), the secondary somatosensory cort...

During disinhibition or low [Mg++](o) buffer, 7-14 Hz ( approximately 10 Hz) oscillations are generated by excitatory networks of interconnected pyramidal cells in motor (agranular) cortex but are absent in barrel (granular) cortex. 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 nec...

Neocortex, the neuronal structure at the base of the remarkable cognitive skills of mammals, is a layered sheet of neuronal tissue composed of juxtaposed and interconnected columns. A cortical column is considered the basic module of cortical processing present in all cortical areas. It is believed to contain a characteristic microcircuit composed of a few thousand neurons. The high degree of c...

The somatosensory neocortex processes extrinsic information from the thalamus and intrinsic information from local circuits. We compared the effects of acetylcholine (Ach) on neocortical field potential responses evoked by stimulation of the whiskers and by local electrical stimulation in the upper layers of the neocortex vibrissae representation ("barrel cortex") of adult rats anesthetized wit...

The barrel field of the somatosensory cortex constitutes a well documented example of anatomofunctional compartmentalization and activity-dependent interaction between neurons and astrocytes. In astrocytes, intercellular communication through gap junction channels composed by connexin 43 and 30 underlies a network organization. Immunohistochemical and electrophysiological experiments were under...

Visual and somatosensory cortices exhibit profound experience-dependent plasticity during development and adulthood and are common model systems for probing the synaptic and molecular mechanisms of plasticity. However, comparisons between the two areas may be confounded by a lack of accurate information on their relative rates of development. In this study, we used whole-cell recording in acute...

The effect of blocking NMDA glutamate receptors in adult rat cortex on experience-dependent synaptic plasticity of barrel cortex neurons was studied by infusing D-AP5 with an osmotic minipump over barrel cortex for 5 d of novel sensory experience. In acute pilot studies, 500 microM D-AP5 was shown to specifically suppress NMDA receptor (NMDAR)-dependent responses of single cells in cortical lay...