The Journal of Neuroscience, June 1, 2005, 25(22):5339-5350; doi:10.1523/JNEUROSCI.0374-05.2005
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Behavioral/Systems/Cognitive
Stimulus-Dependent
(30-50 Hz) Oscillations in Simple and Complex Fast Rhythmic Bursting Cells in Primary Visual Cortex
Jessica A. Cardin,
Larry A. Palmer, and
Diego Contreras
Department of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19106
Oscillatory activity is generated by many neural systems.
band (
40 Hz) oscillations in the thalamus and cortex occur spontaneously and in response to sensory stimuli. Fast rhythmic bursting (FRB) cells (also called chattering cells) comprise a unique class of cortical neurons that, during depolarization by current injection, intrinsically generate bursts of high-frequency action potentials with an interburst frequency between 30 and 50 Hz. In the present study, we show for the first time that FRB cells in the primary visual cortex can be either simple or complex and are distributed throughout all cortical layers. Strikingly, both simple and complex FRB cells generate spike bursts at
frequencies in response to depolarizing current pulses, but only simple FRB cells exhibit a selective, stimulus feature-dependent increase in
oscillations in response to visual stimulation. In addition, we find that hyperpolarization does not reduce the relative power of visually evoked
oscillations in the Vm response of FRB cells. Our results thus indicate that visually evoked
activity in individual simple and complex FRB cells is generated in large part by rhythmic synaptic input, rather than by depolarization-dependent activation of intrinsic properties. Finally, the presence of FRB cells in layer 6 suggests a role for corticothalamic feedback in potentiating thalamic oscillations and facilitating the generation of a corticothalamocortical oscillatory loop. We propose that rather than functioning as pacemakers, FRB cells amplify and distribute stimulus-driven
oscillations in the neocortex.
Key words: contrast; intracellular; orientation; in vivo; intrinsic properties; chattering; feature dependent
Received Jan 27, 2005;
revised April 21, 2005;
accepted April 23, 2005.