Trace conditioning in insects—keep the trace!

Dylla, Kristina V.; Galili, Dana S.; Szyszka, Paul; Lüdke, Alja

doi:10.3389/fphys.2013.00067

Cited by 23 publications

(25 citation statements)

References 108 publications

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“…In olfactory trace conditioning, the reinforcer arrives after the odor stimulus has already terminated, and there is no overlap between the two stimuli. In this situation, the reinforcer arrives when the cytosolic Ca 2+ in KC axon terminals is already back to baseline ( Galili et al, 2011 ; Shuai et al, 2011 ; Szyszka et al, 2011 ; Dylla et al, 2013 , 2017 ). Where, then, is coincidence detection possible for associative trace conditioning?…”

Section: Introductionmentioning

confidence: 99%

Calcium in Kenyon Cell Somata as a Substrate for an Olfactory Sensory Memory in Drosophila

Lüdke

Raiser

Nehrkorn

et al. 2018

Front. Cell. Neurosci.

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Animals can form associations between temporally separated stimuli. To do so, the nervous system has to retain a neural representation of the first stimulus until the second stimulus appears. The neural substrate of such sensory stimulus memories is unknown. Here, we search for a sensory odor memory in the insect olfactory system and characterize odorant-evoked Ca2+ activity at three consecutive layers of the olfactory system in Drosophila: in olfactory receptor neurons (ORNs) and projection neurons (PNs) in the antennal lobe, and in Kenyon cells (KCs) in the mushroom body. We show that the post-stimulus responses in ORN axons, PN dendrites, PN somata, and KC dendrites are odor-specific, but they are not predictive of the chemical identity of past olfactory stimuli. However, the post-stimulus responses in KC somata carry information about the identity of previous olfactory stimuli. These findings show that the Ca2+ dynamics in KC somata could encode a sensory memory of odorant identity and thus might serve as a basis for associations between temporally separated stimuli.

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Section: Introductionmentioning

confidence: 99%

Calcium in Kenyon Cell Somata as a Substrate for an Olfactory Sensory Memory in Drosophila

Lüdke

Raiser

Nehrkorn

et al. 2018

Front. Cell. Neurosci.

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“…Moreover, we found that KC adaptation currents retain a representation of stimulus identity, resembling a prolonged odor trace (Perisse and Waddell, 2011;Dylla et al, 2013). In our model, an odor trace present in adaptation levels extends well beyond the brief spiking responses.…”

Section: Odor Representation In Adaptation Currentsmentioning

confidence: 76%

Circuit and Cellular Mechanisms Facilitate the Transformation from Dense to Sparse Coding in the Insect Olfactory System

Betkiewicz

Lindner

Nawrot

2020

eNeuro

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Transformations between sensory representations are shaped by neural mechanisms at the cellular and the circuit level. In the insect olfactory system, the encoding of odor information undergoes a transition from a dense spatiotemporal population code in the antennal lobe to a sparse code in the mushroom body. However, the exact mechanisms shaping odor representations and their role in sensory processing are incompletely identified. Here, we investigate the transformation from dense to sparse odor representations in a spiking model of the insect olfactory system, focusing on two ubiquitous neural mechanisms: spike Significance Statement In trace conditioning experiments, insects, like vertebrates, are able to form an associative memory between an olfactory stimulus and a temporally separated reward. Forming this association requires a prolonged odor trace. However, spiking responses in the mushroom body, the principal site of olfactory learning, are brief and bound to the odor onset (temporal sparseness). We implemented a spiking network model that relies on spike frequency adaptation to reproduce temporally sparse responses. We found that odor identity is reliably encoded in neuron adaptation levels, which are mediated by spiketriggered calcium influx. Our results suggest that a prolonged odor trace is established in the calcium levels of the relevant neuronal population. This prediction has found recent experimental support in the fruit fly.

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“…Yet, it is still not known whether the same individual mushroom body intrinsic neurons serve both modalities or if there are dedicated subsets for each modality. Moreover, mushroom body neurons were suggested to maintain odor traces in olfactory conditioning [ 8 , 35 ]. Thus, it would be interesting to test whether this is also the case in visual conditioning.…”

Section: Discussionmentioning

confidence: 99%

Reversing Stimulus Timing in Visual Conditioning Leads to Memories with Opposite Valence in Drosophila

2015

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Animals need to associate different environmental stimuli with each other regardless of whether they temporally overlap or not. Drosophila melanogaster displays olfactory trace conditioning, where an odor is followed by electric shock reinforcement after a temporal gap, leading to conditioned odor avoidance. Reversing the stimulus timing in olfactory conditioning results in the reversal of memory valence such that an odor that follows shock is later on approached (i.e. relief conditioning). Here, we explored the effects of stimulus timing on memory in another sensory modality, using a visual conditioning paradigm. We found that flies form visual memories of opposite valence depending on stimulus timing and can associate a visual stimulus with reinforcement despite being presented with a temporal gap. These results suggest that associative memories with non-overlapping stimuli and the effect of stimulus timing on memory valence are shared across sensory modalities.

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Trace conditioning in insects—keep the trace!

Cited by 23 publications

References 108 publications

Calcium in Kenyon Cell Somata as a Substrate for an Olfactory Sensory Memory in Drosophila

Calcium in Kenyon Cell Somata as a Substrate for an Olfactory Sensory Memory in Drosophila

Circuit and Cellular Mechanisms Facilitate the Transformation from Dense to Sparse Coding in the Insect Olfactory System

Reversing Stimulus Timing in Visual Conditioning Leads to Memories with Opposite Valence in Drosophila

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