The Department of Psychology invites you to the first talk of our colloquium series, next Thursday, October 12, from 12:30 - 1:30 pm, by Dr Arij Daou from Biomedical Engineering, AUB. The talk will be held in West Hall, Auditorium B.
Title: Learning rapidly regulates intrinsic properties of cortical neurons
Abstract: Whereas memories are widely thought to be implemented by plasticity in synaptic strength mediated via activity-dependent changes, non-synaptic forms of plasticity have also been implicated. The type and magnitude of ionic currents that a neuron expresses contribute to the number, timing, and patterns of action potentials generated in response to a given input, hence the neuron’s contribution to network dynamics, and ultimately behavior. Here we relate these aspects of neural activity to learned vocalizations in song birds. We show that all basal ganglia–projecting song system “HVCX” neurons recorded in each adult zebra finch brain share similar spike waveform shapes and bursting properties, but these properties vary from bird to bird. Mathematical modeling and physiological studies indicated that the shared properties arise from similar magnitudes of at least five somatic ionic currents. Neurons from different adults were characterized by different combinations of current magnitudes, and this was related to features of the birds’ songs. Sibling birds that learn same songs had precisely overlapping values, and in birds exposed to abnormal (delayed) auditory feedback, the uniformity of intrinsic properties rapidly degraded with singing. Variability in neuronal intrinsic properties was also observed in juvenile birds learning to sing. Overall, our results provide the first example of a long-sought physiological signal that varies rapidly with changes in auditory feedback during singing. We hypothesize that learning and memories are not only encoded at the level of synaptic strengths, but also at the level of ionic channels themselves!