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

Lüdke, Alja; Raiser, Georg; Nehrkorn, Johannes; Herz, Andreas V. M.; Galizia, C. Giovanni; Szyszka, Paul

doi:10.3389/fncel.2018.00128

Cited by 17 publications

(21 citation statements)

References 87 publications

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“…Conditioned and unconditioned stimuli need to be delivered in temporal contiguity, with the US starting a few seconds later than the CS, so that the CS acquires a predictive value for the US (Bitterman et al 1983;Szyszka et al 2011). Conditioning is also possible when there is a temporal gap between the CS and the US, a procedure referred to as trace conditioning (Lüdke et al 2018;Szyszka et al 2011). Conditioning can be absolute, where the bee is exposed to a reward-associated stimulus only and learns its predictive value, or differential, where the animal experiences two stimuli, one of which is paired with a reward (CS+) (Bitterman et al 1983;Matsumoto et al 2012).…”

Section: Classical and Operant Conditioningmentioning

confidence: 99%

Olfactory coding in honeybees

Paoli

Galizia

2021

Cell Tissue Res

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With less than a million neurons, the western honeybee Apis mellifera is capable of complex olfactory behaviors and provides an ideal model for investigating the neurophysiology of the olfactory circuit and the basis of olfactory perception and learning. Here, we review the most fundamental aspects of honeybee’s olfaction: first, we discuss which odorants dominate its environment, and how bees use them to communicate and regulate colony homeostasis; then, we describe the neuroanatomy and the neurophysiology of the olfactory circuit; finally, we explore the cellular and molecular mechanisms leading to olfactory memory formation. The vastity of histological, neurophysiological, and behavioral data collected during the last century, together with new technological advancements, including genetic tools, confirm the honeybee as an attractive research model for understanding olfactory coding and learning.

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Section: Classical and Operant Conditioningmentioning

confidence: 99%

Olfactory coding in honeybees

Paoli

Galizia

2021

Cell Tissue Res

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“…Therefore, classification of calcium levels recorded in the MB should reveal odor identity on a timescale determined by the decay of the intracellular calcium level. Indeed, a recent study by Lüdke et al (2018) showed that prolonged calcium activity in KCs encoded odor information and could be related to behavioral odor recognition performance in trace conditioning experiments where a conditioned odor stimulus is followed by a temporally delayed reinforcement stimulus.…”

Section: Odor Representation In Adaptation Currentsmentioning

confidence: 99%

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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“…Recently, different compartments in Drosophila neurons were discovered to exhibit different odor responses 38 . For example, the odor responses of Kenyon cell (KC) somata exhibit longer odor responses than KC dendrites, with the suggestion that these prolonged responses may hold the memory of a recently sensed odor 38 . To ensure that our analysis of PD2a1/b1 somata captures the essence of PD2a1/b1 neuronal output, we compared the odor responses obtained at PD2a1/b1 somata and axons.…”

Section: Resultsmentioning

confidence: 99%

Differential Role for a Defined Lateral Horn Neuron Subset in Naïve Odor Valence in Drosophila

Lerner

Rozenfeld

Rozenman

et al. 2020

Sci Rep

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Value coding of external stimuli in general, and odor valence in particular, is crucial for survival. In flies, odor valence is thought to be coded by two types of neurons: mushroom body output neurons (MBONs) and lateral horn (LH) neurons. MBONs are classified as neurons that promote either attraction or aversion, but not both, and they are dynamically activated by upstream neurons. This dynamic activation updates the valence values. In contrast, LH neurons receive scaled, but non-dynamic, input from their upstream neurons. It remains unclear how such a non-dynamic system generates differential valence values. Recently, PD2a1/b1 LH neurons were demonstrated to promote approach behavior at low odor concentration in starved flies. Here, we demonstrate that at high odor concentrations, these same neurons contribute to avoidance in satiated flies. The contribution of PD2a1/b1 LH neurons to aversion is context dependent. It is diminished in starved flies, although PD2a1/b1 neural activity remains unchanged, and at lower odor concentration. In addition, PD2a1/b1 aversive effect develops over time. Thus, our results indicate that, even though PD2a1/b1 LH neurons transmit hardwired output, their effect on valence can change. Taken together, we suggest that the valence model described for MBONs does not hold for LH neurons.In order to survive, animals must attach value to external stimuli, be it due to innate or learned behavior. In particular, the ability to accurately evaluate potential food resources is a critical trait for survival. To make such an assessment, animals use many senses, with olfaction often serving as a primary cue. The Drosophila olfactory system resembles that of mammals, including our own, and uses similar principles to decode olfactory information 1,2 . Odors bind to olfactory receptor neurons (ORNs), which are located in the antennae and maxillary palps, where each ORN expresses a single type of odorant receptor (OR) 3-5 . All ORNs expressing the same OR converge onto the same region in the antennal lobe termed the glomerulus 6-8 . Second-order excitatory cholinergic projection neurons (ePNs) have dendrites that are restricted to a single glomerulus, whereas inhibitory GABAergic projection neurons (iPNs) are mostly multiglomerular 9 . Both PN types project to the lateral horn (LH), whereas only ePNs project to the calyx of the mushroom body (MB) 9 . Until recently, associative learning and memory processes were generally believed to occur in the MB, with innate behavior driven by the LH 10,11 . However, although the LH is still believed to contribute greatly to innate behavior, it has become apparent that the rigid functional distinction between the two neuropils cannot be upheld. There is now evidence that the MB also plays a role in some innate olfactory behaviors, mostly attractive 12-14 , while the LH is involved in some forms of associative memory 15 .The LH compartment contains over 1300 cells that are categorized into over 150 types, each with individual morphology 16 . Cells that share mor...

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

Cited by 17 publications

References 87 publications

Olfactory coding in honeybees

Olfactory coding in honeybees

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

Differential Role for a Defined Lateral Horn Neuron Subset in Naïve Odor Valence in Drosophila

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