Reorganization of rat vibrissa barrelfield as studied by cortical lesioning on different postnatal days

Abstract

A small lesion was placed in the rat somatosensory vibrissa cortex on postnatal days (PND) 0, 5, 10, 14 or 20. At the age of three months, the animals were sacrificed and tangential sections of the somatosensory cortex were reacted for detection of succinic dehydrogenase or cytochrome oxidase activity to see if the lesion had produced a defect in the barrelfield. In animals of the groups of PND 0, 5 and 10, the entire barrelfield formed normally, but avoided the lesioned cortex. In a few cases, however, the lesion was found between rows of barrels but never between arcs of barrels. This latter type of result was seen only in the PND-0 group. In animals of the groups of PND 14 and 20, the lesion typically resulted in a defect in the barrelfield. It is concluded that the vibrissa cortex attains its final topographic specificity between day 10 and 14 postnatally. In view of the date of barrelfield formation in normal animals (postnatal day 5), it is thought that the barrelfield is subject to plastic reorganization for some days after its formation; at least for the period between postnatal days 5 and 10.

NMDA receptor-mediated currents are prominent in the thalamocortical synaptic response before maturation of inhibition

“…By mid second postnatal week, IPSCs were strong enough to bring the reversal potential of the thalamocortical response below threshold for NMDAR activation and thus presumably reduce the capacity of the thalamocortical synapse to undergo anatomic and physiological reorganization. Indeed at least one study (Seo and Ito 1987) suggests that the barrel cortex loses its capacity for reorganization around PI 0, coincident with the maturation of inhibition described here. A link between maturation of inhibition and loss of polysynaptic NMDAR-mediated activity in upper layers of rat neocortex has previously been proposed (Luhmann and Prince 1990a,b); our data suggest that a similar process occurs, -1 wk earlier, in the thalamocortical synapse in layer IV.…”

Growth of Thalamic Afferents into Mouse Barrel Cortex

“…16). Before this time, experimental manipulations (peripherally or centrally) can modify the pattern's conformation as seen in the adult animal (Killackeyand Leshin, 1975;Jeanmonod et al, 1981;Ito and Seo, 1983;Durham and Woolsey, 1984;Jensen and Killackey, 1987b;Seo and Ito, 1987). These and other findings (e.g., Durham and Woolsey, 1984) are consistent with the interpretation that the whisker pattern migrates in from the periphery.…”

Selective facilitation of the serotonin1B receptor causes disorganization of thalamic afferents and barrels in somatosensory cortex of rat

“…CO staining is accepted as a reliable method to visualize aggregations of layer IV cortical cells corresponding to mystacial vibrissae (e.g., McCasland and Woolsey, 1988; Jacquin et al, 1993; Haidarliu and Ahissar, 1997), and it has been used extensively in studies of SI development and plasticity in rodents (e.g., Wong‐Riley and Welt, 1980; Wallace, 1987; Seo and Ito, 1987; Chiaia et al, 1992, Chiaia et al, 1996; Hevner et al, 1995; Cases et al, 1996; Vitalis et al, 1998). A CO‐stained section through cortical lamina IV of a control P‐6 animal is shown in Figure 4A.…”