Neurons in the brain engage in collective oscillations in a range of frequencies that span several orders of magnitude. In particular, gamma and high-gamma oscillations (40-100 Hz and above) have been associated with neuronal activation in several brain regions, and are altered in cognitive disorders such as schizophrenia. First proposed as a psychophysiological mechanism for perceptual binding, gamma oscillations are now acknowledged as a general and versatile mechanism of neuronal processing. Gamma oscillations have been shown to be critically dependent on the activity of inhibitory interneurons. In contrast to excitatory neurons, inhibitory interneurons are present in many different subtypes, which differ in their molecular, electrophysiological and anatomical properties. In particular, interneuronal types that are responsible for gamma generation often exhibit active neuronal properties, such as intrinsic subthreshold oscillations. In this talk Dr Baroni will review experimental evidence for the critical involvement of gamma oscillations in different psychological and physiological phenomena, and the key role played by inhibitory interneurons in gamma generation. He will then present simulation results that show how intrinsic subthreshold oscillations enhance gamma oscillations in networks of interneurons coupled with hyperpolarising inhibition, by introducing a depolarising component in the total input current to each cell, which is correlated between neurons that share a large portion of synaptic input. However, the opposite effect is observed if coupling is mediated by shunting inhibition. Finally, Dr Baroni will discuss the implication of these findings for gamma rhythmogenesis in different brain areas, developmental stages and behavioural conditions.
This seminar is part of the NeuroEngineering Lab seminar series and will be presented by Dr Fabiano Baroni, a post-doctoral researcher in the Centre for Neural Engineering at the University of Melbourne.
Next Free Public Lecture:
11 Jun 2013