High and asymmetric somato-dendritic coupling of V1 layer 5 neurons independent of visual stimulation and locomotion

Abstract

Active dendrites impact sensory processing and behaviour. However, it remains unclear how active dendritic integration relates to somatic output in vivo. We imaged semi-simultaneously GCaMP6s signals in the soma, trunk and distal tuft dendrites of layer 5 pyramidal neurons in the awake mouse primary visual cortex. We found that apical tuft signals were dominated by widespread, highly correlated calcium transients throughout the tuft. While these signals were highly coupled to trunk and somatic transients, the frequency of calcium transients was found to decrease in a distance-dependent manner from soma to tuft. Ex vivo recordings suggest that low-frequency back-propagating action potentials underlie the distance-dependent loss of signals, while coupled somato-dendritic signals can be triggered by high-frequency somatic bursts or strong apical tuft depolarization. Visual stimulation and locomotion increased neuronal activity without affecting somato-dendritic coupling. High, asymmetric somato-dendritic coupling is therefore a widespread feature of layer 5 neurons activity in vivo.

Dendritic integration in olfactory bulb granule cells upon simultaneous multispine activation: Low thresholds for nonlocal spiking activity

“…slightly smaller than in earlier reports on mitral/tufted cell to granule cell synaptic transmission [15,24]. Thus, active dendritic mechanisms can be expected to also play a substantial role in granule cell processing in vivo, similar to what has been observed recently for cortical pyramidal cells [39,40].…”

Active dendrites enable strong but sparse inputs to determine orientation selectivity

“…On average, 5.5 ± 2.3 NMDA spikes and 9.9 ± 3.2 dendritic Na + spikes occurred in the relevant time windows before a single AP. Recent in vivo two-photon imaging studies have suggested that local dendritic events are almost always part of a synchronized, multibranch depolarization of the dendrites that is associated with somatic AP firing (54,70). Our results indicate that dendritic events often drive somatic APs, which explains these findings; however, we also find isolated dendritic events that would be more difficult to detect using calcium imaging methods.…”

Reward Association Enhances Stimulus-Specific Representations in Primary Visual Cortex

“…A number of factors can contribute to the salience of a visual stimulus and therefore its behavioral relevance [13], for example, whether a given stimulus is associated with a reward [17][18][19] or an aversive event [5] and whether this association was learned during a behavioral task (e.g., goal-directed behavior) [3,4,20]. Additionally, the behavioral state of an animal, such as whether the animal is stationary or running, modulates the activity of individual neurons in V1 [21][22][23][24][25][26][27][28][29] and affects the representation of visual stimuli [30,31] (but see [32]). While moving through an environment, congruence between an animal's self-motion and optic-flow information results in coupled visuomotor feedback; recent research has revealed that a subpopulation of neurons in V1 responds to a mismatch between optic-flow and self-motion signals when this visuomotor feedback is uncoupled [33][34][35][36].…”