Pavel Itskov

Easy Behavior

Food ingestion is one of the defining behaviours of all animals, but its quantification and analysis remain challenging. This is especially the case for feeding behaviour in small, genetically tractable animals such as Drosophila melanogaster. Here, we present a method based on capacitive measurements, which allows the detailed, automated and high-...

Understanding the mechanisms by which sensory experiences are stored remains a compelling challenge for neuroscience. Previous work has described how the activity of neurons in the sensory cortex allows rats to discriminate the physical features of an object contacted with their whiskers. But to date there is no evidence about how neurons represent...

Rats and mice palpate objects with their whiskers to generate tactile sensations. This form of active sensing endows the animals with the capacity for fast and accurate texture discrimination. The present work is aimed at understanding the nature of the underlying cortical signals. We recorded neuronal activity from barrel cortex while rats used th...

To investigate how hippocampal neurons code behaviorally salient stimuli, we recorded from neurons in the CA1 region of hippocampus in rats while they learned to associate the presence of sound with water reward. Rats learned to alternate between two reward ports at which, in 50% of the trials, sound stimuli were presented followed by water reward...

To survive and successfully reproduce animals need to maintain a balanced intake of nutrients and energy. The nervous system of insects has evolved multiple mechanisms to regulate feeding behavior. When animals are faced with the choice to feed, several decisions must be made: whether or not to eat, how much to eat, what to eat, and when to eat. Us...

The statin drug target, 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), is strongly linked to body mass index (BMI), yet how HMGCR influences BMI is not understood. In mammals, studies of peripheral HMGCR have not clearly identified a role in BMI maintenance and, despite considerable central nervous system expression, a function for central HMGCR...

Animals need to balance competitive behaviors to maintain internal homeostasis. The underlying mechanisms are complex but typically involve neuroendocrine signaling. Using Drosophila, we systematically manipulated signaling between energy-mobilizing endocrine cells producing adipokinetic hormone (AKH), octopaminergic neurons, and the energy-storing...

The assessment of behavioral outcomes is a central component of neuroscientific research, which has required continuous technological innovations to produce more detailed and reliable findings. In this article, we provide an in-depth review on the progress and future implications for three model organisms (mouse, rat, and Drosophila) essential to o...

The regulation of feeding plays a key role in determining the fitness of animals through its impact on nutrition. Elucidating the circuit basis of feeding and related behaviors is an important goal in neuroscience. We recently used a system for closed-loop optogenetic manipulation of neurons contingent on the feeding behavior of Drosophila to disse...

Stress responses are crucial processes that require activation of genetic programs that protect from the stressor. Stress responses are also energy consuming and can thus be deleterious to the organism. The mechanisms coordinating energy consumption during stress response in multicellular organisms are not well understood. Here, we show that loss o...

The regulation of feeding plays a key role in determining the fitness of animals through its impact on nutrition. Elucidating the circuit basis of feeding and related behaviors is an important goal in neuroscience. We recently used a system for closed-loop optogenetic manipulation of neurons contingent on the fly’s feeding behavior to dissect the i...

To optimize fitness, animals must dynamically match food choices to their current needs. For drosophilids, yeast fulfills most dietary protein and micronutrient requirements. While several yeast metabolites activate known gustatory receptor neurons (GRNs) inDrosophila melanogaster, the chemosensory channels mediating yeast feeding remain unknown. H...

Supplementary Tables 1-3.

To optimize fitness, animals must dynamically match food choices to their current needs. For drosophilids, yeast fulfils most dietary protein and micronutrient requirements. While several yeast metabolites activate known gustatory receptor neurons (GRNs) in Drosophila melanogaster , the chemosensory channels mediating yeast feeding remain unknown....

Choosing the right nutrients to consume is essential to health and wellbeing across species. However, the factors that influence these decisions are poorly understood. This is particularly true for dietary proteins, which are important determinants of lifespan and reproduction. We show that in Drosophila melanogaster, essential amino acids (eAAs) a...

Henna RNAi leads to specific gene knockdown, and the knockdown effect on food choice is Tyr and tissue specific. (A) Henna mRNA levels measured from whole flies and normalized to two internal controls (Actin 42A and RpL32). The columns represent the mean and the error bars the standard error of the mean. n = 6. (B) Feeding preference of Henna knock...

Commensal bacteria can reduce the protein appetite induced by dietary removal of any eAA. Feeding preference of animals kept either on holidic medium, or holidic medium lacking one of the 10 eAAs with or without pretreatment with 5 bacteria commensal mix. Data on the different graphs were collected on two independent days. Circles represent yeast p...

A non-commensal bacterium does not reduce yeast preference and commensal bacteria also affect food choice on low-yeast diets. (A) Feeding preference of animals kept either on holidic medium, or holidic medium lacking His with or without pretreatment with the 5 commensal bacteria mix or E. coli. Circles represent yeast preference in single assays, w...

Commensal bacteria reduce yeast preference in Henna knockdown flies upon eAA deprivation. Feeding preference of control and Henna knockdown animals kept on holidic medium, or holidic medium lacking His with or without pretreatment with 5 commensal bacteria mix. n = 20. Circles represent yeast preference in single assays, with line representing the...

Diagram depicting the chronology of the dietary and microbial manipulations of flies used in experiments. (TIF)

Nucleotide sequence of primers used for qRT-PCR. (DOCX)

Deprivation of amino acids specifically increases amino acid appetite. (A) Feeding assay in which flies were given the choice between the holidic medium lacking AAs (sucrose option) and the holidic medium lacking sucrose and one of the different nutrient classes. Animals were either kept on full holidic medium or holidic medium lacking AAs. (B) Fee...

Recipe for generation of HM used in this study. Gray fields indicate manipulated nutrients. (DOCX)

Detailed composition of amino acid solutions for HM used in this study. (DOCX)

Levels of internal microbes in non-axenic flies. The internal load of bacteria inside flies was calculated as CFU/fly after bacterial colony count on LB (A), Mannitol (B), or MRS (C) media which sustain the growth of different bacterial species as indicated in the title of each graph. The load of bacteria was assessed for flies kept on holidic medi...

A. pomorum and Lactobacilli are sufficient to reduce the yeast appetite induced by dietary removal of isoleucine. Numbers of sips on yeast as measured using the flyPAD of axenic flies pre-fed complete holidic medium or holidic medium without Ile and pretreated with different bacterial mixes. Filled black circles represent complete holidic medium or...

Detailed genotypes of flies used in this study. (DOCX)

Raw data used for generation of all figures. (XLSX)

The design of modern scientific experiments requires the control and monitoring of many different data streams. However, the serial execution of programming instructions in a computer makes it a challenge to develop software that can deal with the asynchronous, parallel nature of scientific data. Here we present Bonsai, a modular, high-performance,...

The global rise in obesity has revitalized a search for genetic and epigenetic factors underlying the disease. We present a Drosophila model of paternal-diet-induced intergenerational metabolic reprogramming (IGMR) and identify genes required for its encoding in offspring. Intriguingly, we find that as little as 2 days of dietary intervention in fa...

The design of modern scientific experiments requires the control and monitoring of many different data streams. However, the serial execution of programming instructions in a computer makes it a challenge to develop software that can deal with the asynchronous, parallel nature of scientific data. Here we present Bonsai, a modular, high-performance,...

Because acoustic landscapes are complex and rapidly changing, auditory systems have evolved mechanisms that permit rapid detection of novel sounds, sound source segregation and perceptual restoration of sounds obscured by noise. Perceptual restoration is particularly important in noisy environments, because it allows organisms to track sounds over...

To investigate how hippocampal neurons encode sound stimuli, and the conjunction of sound stimuli with the animal's position in space, we recorded from neurons in the CA1 region of hippocampus in rats while they performed a sound discrimination task. Four different sounds were used, two associated with water reward on the right side of the animal a...

Hippocampal neuronal ensemble activity appears to play an important role in establishment of spatial and non-spatial episodic memories [1] and [2]. In particular, CA1 region of the hippocampus is well known to be a crucial site for processing associative memories which typically contain information about what, where, and when major behavioral event...

Example of Discontinuity illusion stimulus: Continuous tone with spectrally remote noise. The tone sounds discontinuous to some listeners. (WAV)

Example of Continuity illusion stimulus (noise duration 50 ms). (WAV)

Preliminary Data Streaming and illusory discontinuity are related. (DOC)

No relationship between noise detection thresholds and continuity/discontinuity perception. (DOC)

Important sounds can be easily missed or misidentified in the presence of extraneous noise. We describe an auditory illusion in which a continuous ongoing tone becomes inaudible during a brief, non-masking noise burst more than one octave away, which is unexpected given the frequency resolution of human hearing. Participants strongly susceptible to...

The rodent whisker system has become the leading experimental paradigm for the study of active sensing. Thanks to more sophisticated behavioral paradigms, progressively better neurophysiological methods, and improved video hardware/software, there is now the prospect of defining the precise connection between the sensory apparatus and brain activit...

Experimental conditions. (DOC)

Separation between pyramidal cells and interneuron's. Three criteria were used to separate pyramidal cells: mean firing rate[51], [52], spike duration[53], and the autocorrelation function[54]. Firing rate was measured over the whole session. Spike duration was initially measured from peak-to-valley[3] and at 25% of maximum spike amplitude[54]; the...

Ripple events. (A) Raw (unfiltered) local field potential voltage trace aligned on the maximum of the ripple event. (B) 120–240 Hz band pass filtered local field potential of the same voltage trace. (C) Raster plot of 23 simultaneously recorded neurons aligned on the ripple event. Red – pyramidal cells, blue – interneurons. (D) Relationship between...

Representation of texture without reward location. Presence of a texture signal does not require the presence of a reward location signal. (A) The firing rates profiles associated with the animal's selection of the left and right reward locations were overlapping at all times on platform A. (B) Firing rate profiles associated with the left reward l...

Independence of populations recruited to encode texture in different locations. In the two-platform task, neurons were tested for the presence of texture information on four occasions (the left and right texture pairs on platform A, and the left and right texture pairs on platform B). We asked whether the presence or absence of information about te...

Information about texture is distributed across neurons over time. Information profiles of 4 simultaneously recorded neurons. Only traces of information associated with right turn on platform B are shown. Note that simultaneously recorded neurons carried information about texture at different points in time. Such a distribution of information was t...

Firing of reward location neurons during incorrect trials. In our experiments, the number of error trials was low. For this reason, we were not able to obtain clear or stable statistical results on error trials. Nevertheless, in a few cases, there was a sufficient number of error trials, and with the same temporal rhythm, to allow spike times to be...

Texture neurons meta-analysis. To estimate the probability of finding the number of neurons with the significance threshold of p<0.05 we have performed a meta-analysis of the data. The distribution in blue represents the number of neurons which is expected to surpass our threshold of significance (scrambled) in averaged across all four reward locat...

(AVI)

Spike sorting and histology. (A) Waveforms of seven single units isolated from one tetrode. This recording is typical of those in which more than 5 neurons were isolated. Vertical scale bars represent 150 microvolts. (B) Scatter plot of waveform energy from two channels of the tetrode demonstrating separation of units; grey dots are events unaccoun...

Reward-aligned local field potentials in a single trial. (A) Raw local field potential voltage trace (black) and 5–12 Hz (theta) filtered voltage trace (red). Red, blue, and green vertical dashed lines indicate the estimated start of time windows during which rats engaged in touch, turn and reward collection. (B) 18–35 Hz (beta and low gamma) band...

Tactile stimuli. Photographs of rough tactile discrimanda, textures 2–4 (T2–T4). T1 was a smooth plate. Scale bar is 10 mm. (TIF)

A numerical thought experiment was conducted to assess whether stimulus-specific, short-term changes in auditory neural responsiveness could explain the formation of auditory objects underlying the auditory continuity illusion. A tonotopic, two-layer feedforward network model with one time constant for synaptic weight augmentation based on firing r...

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Overhead View of 1-Arm Task Three trials of the 1-arm task. The film is slowed down by a factor of 4. Note the two mobile parts: on the rotating platform facing the rat, the textures are mounted. The rotating object in front of the rat's platform is a paw support. It is retracted when the texture is changed to ensure that the rat cannot touch the d...

To study the neurophysiology of large-scale spatial cognition, we analyzed the neuronal activity of navigating homing pigeons. This is not possible using conventional radio-telemetry suitable for short distances only. Therefore we developed a miniaturized data logger ("neurologger") that can be carried by a homing pigeon on its back, in conjunction...