Variation in the spatial relationship between parvalbumin immunoreactive interneurones and pyramidal neurones in rat somatosensory cortex

The morphology of pyramidal neurones was revealed by intracellular injection of Lucifer Yellow (LY) in fixed tangential cortical slices taken from rat primary somatosensory cortex. Slices were processed with a combination of antibodies to allow visualization of both the LY-injected neurones and parvalbumin immunoreactive (PV-ir) cell bodies, by confocal microscopy. Basal dendritic fields of pyramidal neurones in layer V were larger and more complex than those of layer III. Furthermore, the number of PV-ir cell bodies contained within the basal dendritic territories of pyramidal neurones in layer V was significantly greater than in layer III (mean ± s.e.m., 36.3 ± 3.0 and 20.9 ± 1.6, respectively). These findings have functional implications both in terms of physiological characteristics, and inhibitory modulation of receptive field properties, of cortical neurones.