TY  - JOUR
AB  - In many neurons, strong excitatory stimulation causes an after-hyperpolarization (AHP) at stimulus offset, which might give rise to activity-dependent adaptation. Graded-potential visual motion-sensitive neurons of the fly Calliphora vicina respond with depolarization and hyperpolarization during motion in their preferred direction and their anti-preferred direction, respectively. A prominent after-response, opposite in sign to the response during motion, is selectively expressed after stimulation with preferred-direction motion. Previous findings suggested that this AHP is generated in the motion-sensitive neurons themselves rather than in presynaptic processing layers. However, it remained unknown whether the AHP is caused by membrane depolarization itself or by another process, e.g. a signaling cascade triggered by activity of excitatory input channels. Here we showed by current injections and voltage clamp that the AHP and a corresponding current are generated directly by depolarization. To test whether the generation of an AHP is linked to depolarization via a Ca(2+)-dependent mechanism, we used photoactivation of a high-affinity Ca(2+) buffer. In accordance with previous findings the AHP was insensitive to manipulation of cytosolic Ca(2+). We propose that membrane depolarization presents a more direction-selective mechanism for the control of AHP than other potential control parameters.
DA  - 2009
DO  - 10.1111/j.1460-9568.2009.06854.x
KW  - invertebrate
KW  - calcium
KW  - voltage clamp
KW  - adaptation
KW  - vision
LA  - eng
IS  - 4
M2  - 567
PY  - 2009
SN  - 0953-816X
SP  - 567-577
T2  - European Journal of Neuroscience
TI  - Mechanisms of after-hyperpolarization following activation of fly visual motion-sensitive neurons
UR  - https://nbn-resolving.org/urn:nbn:de:0070-pub-15910483
Y2  - 2024-11-24T04:35:49
ER  -