Binding-by-bursting: A new theory of attentional binding and the neural correlates of consciousness
55.15, Tuesday, May 14, 5:15 - 7:15 pm, Royal Ballroom 1-3
Peter Tse1; 1Dept. Psychological and Brain Sciences, Dartmouth College
I will review neurophysiological evidence supporting the view that endogenous attentional binding consists in transitioning a neural circuit from a tonic to a phasic mode of firing via cholinergic feedback from the basal forebrain and other areas, characterized by an increased probability of burst transmission up and down the ventral pathway. Binding-by-bursting emphasizes decorrelation in firing (Cohen & Maunsell, 2009, 2011) and an increase in bursting (Anderson et al., 2011) over synchronous firing. On this view, increased power of gamma oscillations with attention (Fries et al., 1997, 2001a,b, 2002, 2007, 2008; Gray, 1999; Singer, 1999a,b, 2004; Uhlhaas et al., 2009) arises not primarily from synchronous firing, although synchronous bursting is important; it arises from the synchronous subthreshold inputs to postsynaptic neurons imposed by the inhibitory interneuron "clock" (Buzsáki & Chrobak, 1995; Bartos et al., 2007; Kawaguchi et al., 1987). What "binding by bursting" provides is not the gluing of features together at a location, but rather the complete information-processing treatment of the entire hierarchical circuit within the attended domain. Processing outside of the attended domain does not receive a circuitÂ’s complete information-processing treatment because it remains in tonic firing mode, and may undergo burst suppression. If single spikes are "filtered out" (Lisman, 1997), then downstream neurons will not respond well to tonic input, unless it arrives synchronously. Entering phasic mode enhances information processing, especially in later stages of a hierarchy, because burst packets corresponding to a given bottom-level input will propagate the entire hierarchy in a coherent sequence. Thus, detected information will be processed from beginning to end, or bottom to top of an information-processing Â‘stack,Â’ in the case of the ventral pathway, up to recognition. Particular emphasis will be placed on the importance of onset transients in opening NMDA receptors. The theory is detailed in Tse (2013, MIT Press).