Abstract
In the primary visual cortex, activity of neurons evoked by stimuli within the classical receptive field (CRF) can be modulated by stimuli in the extra-receptive field (ERF). This modulating effect can be facilitatory (F-ERF) or inhibitory (I-ERF) that play different roles in visual information processing. Little is known on the neurotransmitter receptor bases of the two types of long-range interactions. Using in vivo intracellular injection technique, combined with the technique of immunocytochemistry, we have studied the immunocytochemical features of the F-ERF and I-ERF neurons. Significant differences were found in type, density and distribution of neurotransmitter receptors between the two types of neurons. F-ERF neurons have densely distributed Glu2/3 receptors and relatively small amount of GABAA receptors on the surface of proximal dendrites and cell body, and the reverse is true for I-ERF neurons. As the Glu2/3 receptors are the main targets of excitatory synaptic input and the GABAA receptors are the main targets of inhibibory synaptic input, the differences in receptor characteristics between the I-ERF and F-ERF neurons may underlie the distinct long-range modulation effects of the two types of neurons.