Selective suppression of horizontal propagation in rat visual cortex by norepinephrine
Masayuki Kobayashi,1 Kazuyuki Imamura,1,5 Tokio Sugai,2 Norihiko Onoda,2 Masao Yamamoto,1,3 Shoji Komai1,4 and Yasuyoshi Watanabe1, 5
European Journal of Neuroscience, (2000) 12 (1) 264-272
The release of norepinephrine in the cerebral cortex from axon terminals of locus coeruleus neurons was suggested to be involved in the control of attention. Accumulating data indicate that the responses of cortical neurons are varied when norepinephrine is applied iontophoretically in the vicinity of the cells being recorded. However, it is not known how the pattern of excitatory propagation is modified when norepinephrine is applied over a wide area in the visual cortex. By applying optical imaging to rat visuocortical slices, we found a new mode of norepinephrine action; a prominent suppression of the horizontal propagation in layers II/III. This action of norepinephrine was confirmed by the simultaneous recording of field potentials from multiple sites by use of a multi-electrode dish. Furthermore, our electrophysiological recordings showed that this norepinephrine action is exerted through suppression of excitatory neural transmission and enhancement of inhibitory transmission to the pyramidal neurons in these layers. Because the release of norepinephrine in the visual cortex is regulated by the level of attention, the neural basis of visual attention may relate partially to the suppression of the integration of visual information by norepinephrine resulting in a state-dependent restructuring of the receptive field.
Link to European Journal of Neuroscience
