Martin Deschenes

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A sample of 84 neurons in lamina VIa of rat somatosensory cortex (S1) was juxtacellularly labeled with biocytin, and the axons of the neurons were traced. Three classes of cells were identified as corticothalamic, corticocortical, and local circuit neurons. Corticothalamic cells (46%) are small, short pyramids projecting either to the ventral posteromedial(More)
This study investigated the pattern of axonal projections of single corticothalamic neurons from the cortical barrel field representing the vibrissae in the rat. Microiontophoretic injections of biocytin were performed in cortical layers V and VI to label small pools of corticothalamic cells and their intrathalamic axonal projections. After a survival(More)
All neocortical areas receive inputs from and project back to the thalamus. It is often said that the corticothalamic projections are organized in a way that reciprocates the spatial distribution of thalamocortical pathways. The present review examines to what extent this rule of reciprocity is actually supported by the most recent neuroanatomical data,(More)
This study investigated the organization of a vibrissal pathway that arises from the interpolar division of the spinal trigeminal complex (SP5i), transits through the ventral posterior medial nucleus (VPM), and innervates the somatosensory cortical areas in the rat. Using Fluoro-Gold and biotinylated dextran amine, respectively, as retrograde and(More)
This study investigated the relationship between axonal projections and receptive field properties of whisker-sensitive cells in the principal trigeminal sensory nucleus of the rat. The labeling of small groups of trigeminothalamic axons with biotinylated dextran amine disclosed two broad classes of axons; a majority of fibers (68%; n = 107) project to a(More)
This study investigated the axonal projections of whisker-sensitive cells of the spinal trigeminal subnuclei (SP5) in rat oral, interpolar, and caudal divisions (SP5o, SP5i, and SP5c, respectively). The labeling of small groups of trigeminothalamic axons with biotinylated dextran amine disclosed the following classes of axons. 1) Few SP5o cells project to(More)
Sensory stimuli evoke strong responses in thalamic relay cells, which ensure a faithful relay of information to the neocortex. However, relay cells of the posterior thalamic nuclear group in rodents, despite receiving significant trigeminal input, respond poorly to vibrissa deflection. Here we show that sensory transmission in this nucleus is impeded by(More)
The hypothesis that nucleus reticularis thalami (RE) is the generator of spindle rhythmicity during electroencephalogram (EEG) synchronization was tested in acutely prepared cats. Unit discharges and focal waves were extracellularly recorded in the rostral pole of RE nucleus, which was completely disconnected by transections from all other thalamic nuclei.(More)
1. Intracellularly recorded low- and high-frequency (4-6 and 25-50 Hz, respectively), rhythmic, spontaneous membrane potential oscillations were investigated in pyramidal neurons of the rat hippocampus in vivo, during theta (theta, 4-6 Hz) electroencephalographic (EEG) activity, under ketamine-xylazine anesthesia. 2. The EEG activity showed two spectral(More)