William Phillips, University of Stirling, UK

Evolutionary and developmental transformations of apical function in neocortical pyramidal cells

In reptilian 3-layer cortex and in immature mammalian 6-layer neocortex apical inputs provide excitatory drive to pyramidal cells. In mature neocortex apical input modulates response to basal input by amplifying signals that are relevant in the current context while suppressing those that are irrelevant or interfering as hypothesized by the theory of coherent infomax. This context-sensitive flexibility depends upon HCN channels that have a long post-natal developmental time-course, and which tend to isolate distal apical input from the soma unless they are closed by the adrenergic system. Adrenergic arousal turns apical amplification (AA) on when we awake and turns it up when we attend, thus suggesting that AA is closely related to conscious state, as others have suggested. Computational studies indicate that AA can be used in algorithms for Gestalt organization, contextual disambiguation, priming, attention, and invariant object recognition. It is likely that malfunctions of AA are involved in several neurodevelopmental disorders. For an open-access review see: http://nc.oxfordjournals.org/cgi/reprint/niw015

Organized by

Matthew Larkum