Inhibitory circuits in sensory maps develop through excitation

Abstract

Inhibitory and excitatory connections are equal partners in determining neuronal response properties. Although the development and plasticity of excitatory networks have been heavily studied, little is known about how inhibitory circuits develop. In a recent study, Gunsoo Kim and Karl Kandler have shown that, as in the development of excitatory circuits, synapse elimination and strengthening are important processes for the development of well-organized inhibitory circuits.The sensory world is mapped with great precision at many levels of the CNS. The response properties of the cells within these maps are derived from the interaction of excitatory and inhibitory inputs. Although understanding how the excitatory inputs develop their precise connections has been a significant focus of developmental neurobiology over the past 40 years, very little is known about how inhibitory circuits develop in the context of a sensory map. In their recent study [1], Kim and Kandler show that inhibitory circuits are refined by some of the same processes as excitatory circuits.

Pathway specificity of dendritic spine morphology in identified synapses onto rat hippocampal CA1 neurons in organotypic slices

“…The decrease in connectivity at 4 weeks in vitro is difficult to interpret as we have no previous data from this stage. While this would be consistent with the retraction of synapses that occurs in many regions of the brain during development (e.g., for review Issa, 2003), it could also represent a pathological decrease because of the time the slice has been kept in culture. We have thus not studied this stage of development in any other pathways.…”

Physiological consequences of selective suppression of synaptic transmission in developing cerebral cortical networks in vitro: Differential effects on intrinsically generated bioelectric discharges in a living ‘model’ system for slow-wave sleep activity

“…In light of the fact that burst durations in mature occipital cortex cultures are greatly lengthened by the acute administration of GABAergic receptor blockers (Corner et al, 2002), inhibitory feedback is likely to become a major contributory factor to burst attenuation as development proceeds. Indeed, synaptic inhibition is known to be one of the prime activity-dependent mechanisms throughout the developing central nervous system (reviewed in Corner et al, 2002;further, Chattopadhyaya et al, 2004;De Lima et al, 2004, 2007Issa, 2003;Kotak and Sanes, 2003;Palizvan et al, 2004;Rosato-Siri et al, 2002;Tao and Poo, 2005).…”

Mechanism of auditory hypersensitivity in human autism using autism model rats

“…In contrast, nerve fibers from the MNTB to the LSO have an inhibitory function, using glycine as a transmitter (Fig. ) . Therefore, auditory hypersensitivity might occur by abnormalities in or loss of function of the inhibitory neurons of the auditory nervous system.…”

“…1). [16][17][18] Therefore, auditory hypersensitivity might occur by abnormalities in or loss of function of the inhibitory neurons of the auditory nervous system.…”