Electrophysiological analysis and computational modelling of dendritic processing by feature detection neurons in insects
(2026) MOBN03 20251Degree Projects in Molecular Biology
- Abstract
- Many insects have a behavioral need for the rapid detection of small moving visual targets. In dragonflies and flies, Small Target Motion Detector (STMD) neurons have been found to fill this function, but observations in Hymenopterans raise questions of whether similar neurons are present. In high order variants of these neurons, predictive response gain modulation thought to be driven by dendritic signaling has been observed. Throughout the project, in vivo intracellular electrophys-iology was used to study the characteristics of lobula neurons in the European wool carder bee with the aim of providing evidence for STMD-like neurons. Cells with clear response peaks to targets of small angular area were identified, showing many similarities... (More)
- Many insects have a behavioral need for the rapid detection of small moving visual targets. In dragonflies and flies, Small Target Motion Detector (STMD) neurons have been found to fill this function, but observations in Hymenopterans raise questions of whether similar neurons are present. In high order variants of these neurons, predictive response gain modulation thought to be driven by dendritic signaling has been observed. Throughout the project, in vivo intracellular electrophys-iology was used to study the characteristics of lobula neurons in the European wool carder bee with the aim of providing evidence for STMD-like neurons. Cells with clear response peaks to targets of small angular area were identified, showing many similarities to higher order STMDs in dragonflies. These findings highlight how foundational STMDs seem to be for effective visual processing. Additionally, in this project a new virtual simulation environment and a novel morphological analysis of the afferent pellucid fly SF-STMD were constructed with the aim of simulating calcium wave kinetics in its dendritic tree. I present indications that calcium wave propagation inside dendritic trees might provide a mechanism for the long time scale facilitatory properties of higher order STMDs. The created simulation scripts also provide a framework for future work. (Less)
- Popular Abstract
- The Tree of Knowledge of Small and Fast
Insecta is perhaps not the first animal class that comes to mind when discussing super precise visual systems, but fact is that being able to detect tiny visual cues is a matter a life and death for many of its species. Dragonflies hunt mosquitoes in cluttered environments and hoverflies hunt away rivals encroaching on their territory – both with incredible precision.
Responsible for these behaviors is a group of insect neurons called Small Target Motion Detectors (STMDs), sending strong signals when spotting small, moving targets. To date these have been found in various dragonfly and fly species, but it turns out many other insect species – such as the European wool carder bee – perform many... (More) - The Tree of Knowledge of Small and Fast
Insecta is perhaps not the first animal class that comes to mind when discussing super precise visual systems, but fact is that being able to detect tiny visual cues is a matter a life and death for many of its species. Dragonflies hunt mosquitoes in cluttered environments and hoverflies hunt away rivals encroaching on their territory – both with incredible precision.
Responsible for these behaviors is a group of insect neurons called Small Target Motion Detectors (STMDs), sending strong signals when spotting small, moving targets. To date these have been found in various dragonfly and fly species, but it turns out many other insect species – such as the European wool carder bee – perform many of the same impressive visually guided behaviours. So do bees also have STMD neurons? This was the first question I intended to answer in my project.
Electrical studies into this cell group have revealed that they store information on where a visual target has previously traveled as it traverses over the visual field of the animal. The cells then use this information to predict future locations. Like in many other neurons, the site at which STMDs recieve signals from the eyes has an elaborate tree-like structure. It is hypothesised that a traveling molecular wave mechanism inside this arborised tree is the basis for the information storage. Can the electrical observations be explained by a wave mechanism? This was the second question driving my project.
To answer the first question, I performed electrical brain recordings on wool carder bees while presenting them with small moving targets on a monitor. There was clear evidence of cells firing off when presented targets were especially small – precisely what you see in dragonflies and flies.
The second question was investigated through virtual simulations. The results seem to indicate molecular waves as a good candiate for past-path storage, with waves essentially continuously updating the cell about where a target has been and where it will likely show up in the near future.
STMDs are highly sophisticated, but they turn out to be more widely utilised than previously known. To understand how common they really are among insects, and to truly grasp all their complex properties, more studies into these remarkable cells are needed.
Masterexamensarbete i molekylarbiologi 60 hp 2026
Biologiska Instutitionen, Lunds universitet
Handledare: David O’Carroll, Elisa Rigosi
Division of Sensory Biology (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9224947
- author
- Vadebo, Erik
- supervisor
-
- David O'Carroll LU
- Elisa Rigosi LU
- organization
- course
- MOBN03 20251
- year
- 2026
- type
- H2 - Master's Degree (Two Years)
- subject
- language
- English
- id
- 9224947
- date added to LUP
- 2026-03-30 12:19:25
- date last changed
- 2026-03-30 13:09:01
@misc{9224947,
abstract = {{Many insects have a behavioral need for the rapid detection of small moving visual targets. In dragonflies and flies, Small Target Motion Detector (STMD) neurons have been found to fill this function, but observations in Hymenopterans raise questions of whether similar neurons are present. In high order variants of these neurons, predictive response gain modulation thought to be driven by dendritic signaling has been observed. Throughout the project, in vivo intracellular electrophys-iology was used to study the characteristics of lobula neurons in the European wool carder bee with the aim of providing evidence for STMD-like neurons. Cells with clear response peaks to targets of small angular area were identified, showing many similarities to higher order STMDs in dragonflies. These findings highlight how foundational STMDs seem to be for effective visual processing. Additionally, in this project a new virtual simulation environment and a novel morphological analysis of the afferent pellucid fly SF-STMD were constructed with the aim of simulating calcium wave kinetics in its dendritic tree. I present indications that calcium wave propagation inside dendritic trees might provide a mechanism for the long time scale facilitatory properties of higher order STMDs. The created simulation scripts also provide a framework for future work.}},
author = {{Vadebo, Erik}},
language = {{eng}},
note = {{Student Paper}},
title = {{Electrophysiological analysis and computational modelling of dendritic processing by feature detection neurons in insects}},
year = {{2026}},
}