Esa-Ville Immonen

• PhD in Biophysics
• PostDoc Position at University of Oulu

The common backswimmer, Notonecta glauca, uses vision by day and night for functions such as underwater prey animal capture and flight in search of new habitats. Although previous studies have identified some of the physiological mechanisms facilitating such flexibility in the animal's vision, neither the biophysics of Notonecta photoreceptors nor...

To avoid the fierce competition for food, South African ball-rolling dung beetles carve a piece of dung off a dung-pile, shape it into a ball and roll it away along a straight line path. For this unidirectional exit from the busy dung pile, at night and day, the beetles use a wide repertoire of celestial compass cues. This robust and relatively eas...

Key points: The principles underlying the evolutionary selection of ion channels for expression in sensory neurons are unclear. Photoreceptor depolarization in the diurnal Drosophila melanogaster is predominantly provided by light-activated transient receptor potential (TRP) channels, whereas repolarization is mediated by sustained voltage-gated K...

Night vision is ultimately about extracting information from a noisy visual input. Several species of nocturnal insects exhibit complex visually guided behaviour in conditions where most animals are practically blind. The compound eyes of nocturnal insects produce strong responses to single photons and process them into meaningful neural signals, w...

The potassium-chloride co-transporter 2, KCC2, is a neuron-specific ion transporter that plays a multifunctional role in neuronal development. In mature neurons, KCC2 maintains a low enough intracellular chloride concentration essential for inhibitory neurotransmission. During recent years, pathogenic variants in the KCC2 encoding gene SLC12A5 aect...

Purpose: Next-generation sequencing (NGS) has made genetic testing of patients with epileptic encephalopathies easier - novel variants are discovered and new phenotypes described. Variants in the same gene - even the same variant - can cause different types of epilepsy and neurodevelopmental disorders. Our aim was to identify the genetic causes of...

Absence of screening pigment in insect compound eyes has been linked to visual dysfunction. We investigated how its loss in a white-eyed mutant (W-E) alters the photoreceptor electrophysiological properties, opsin gene expression, and the behavior of the cockroach, Periplaneta americana. Whole-cell patch-clamp recordings of green-sensitive photorec...

The compound eye of Periplaneta americana contains two spectral classes of photoreceptors: narrow-band UV-sensitive and broad-band green-sensitive. In intracellular recordings, stimulation of green-sensitive photoreceptors with flashes of relatively bright UV/violet light produced anomalous delayed depolarization after the end of the normal light r...

Plasticity is a crucial aspect of neuronal physiology essential for proper development and continuous functional optimization of neurons and neural circuits. Despite extensive studies of different visual systems, little is known about plasticity in mature microvillar photoreceptors. Here we investigate changes in electrophysiological properties and...

Electrophysiological studies in Drosophila melanogaster and Periplaneta americana have found that the receptor current in their microvillar photoreceptors is generated by two light-activated cationic channels, TRP (transient receptor potential) and TRPL (TRP-like), each having distinct properties. However, the relative contribution of the two chann...

We describe a new nonlinear dynamic model of insect phototransduction using a NLN (nonlinear, linear, nonlinear) block structure. The first nonlinear stage provides a single exponential decline in gain and mean following the start of light stimulation. The linear stage uses a two-parameter log-normal convolution model previously applied alone to in...

Voltage-activated potassium channels (Kv channels) in the microvillar photoreceptors of arthropods are responsible for repolarization and regulation of photoreceptor signaling bandwidth. On the basis of analyzing Kv channels in dipteran flies it was suggested that diurnal, rapidly-flying insects predominantly express sustained potassium conductance...

In a microvillar photoreceptor, absorption of an incident photon initiates a phototransduction reaction that generates a depolarizing light-induced current (LIC) in the microvillus. Although in-depth knowledge about these processes in photoreceptors of the fruitfly Drosophila is available, not much is known about their nature in other insect specie...

Shannon's seminal approach to estimating information capacity is widely used to quantify information processing by biological systems. However, the Shannon information theory, which is based on power spectrum estimation, necessarily contains two sources of error: time delay bias error and random error. These errors are particularly important for sy...

The compound eye of the cricket Gryllus bimaculatus contains a specialized dorsal rim area (DRA) populated by distinct blue-sensitive photoreceptors responsible for perception of polarized light. The rest of the eye is dominated by green-sensitive photoreceptors. Using patch clamp we studied dissociated ommatidia of nocturnal adults and diurnal eig...

Optimization of sensory processing during development can be studied by using photoreceptors of hemimetabolous insects (with incomplete metamorphosis) as a research model. We have addressed this topic in the stick insect Carausius morosus, where retinal growth after hatching is accompanied by a diurnal-to-nocturnal shift in behavior, by recording f...

In dim light, scarcity of photons typically leads to poor vision. Nonetheless, many animals show visually guided behaviour with dim environments. We investigated the signaling properties of photoreceptors of dark-active cockroach (Periplaneta americana), using intracellular and whole-cell patch-clamp recordings, to determine whether they show selec...

The importance of voltage-dependent conductances in sensory information processing is well-established in insect photoreceptors. Here we present the characterization of electrical properties in photoreceptors of the cockroach (Periplaneta americana), a nocturnal insect with a visual system adapted for dim light. Whole-cell patch-clamped photorecept...