Using TrackMate to Analyze Drosophila Larval and Adult Locomotion

Drosophila adult and larvae exhibit sophisticated behaviors that are widely used in development, synaptic transmission, sensory physiology, and learning and memory research. Many of these behaviors depend on locomotion, the ability of an animal to move. However, the statistical analysis of locomotion is not trivial. Here we use an open-source Fiji plugin TrackMate to track the locomotion of Drosophila adults and larvae. We build optimal experimental setups to rapidly process recordings by Fiji and analyze by TrackMate. We also provide tips for analyzing non-optimal recordings. TrackMate extracts the X and Y positions of an animal on each frame of an image sequence or a video. This information allows for generating moving trajectories, calculating moving distances, and determining preference indices in two-choice assays. Notably, this free-cost analysis method does not require programming skills.Summary statementThis study uses an open-source Fiji plugin TrackMate to computationally analyze Drosophila adult and larval behavioral assays, which does not require programming skills.

Role of the TRP Channels in Pancreatic Ductal Adenocarcinoma Development and Progression

The transient receptor potential channels (TRPs) have been related to several different physiologies that range from a role in sensory physiology (including thermo- and osmosensation) to a role in some pathologies like cancer. The great diversity of functions performed by these channels is represented by nine sub-families that constitute the TRP channel superfamily. From the mid-2000s, several reports have shown the potential role of the TRP channels in cancers of multiple origin. The pancreatic cancer is one of the deadliest cancers worldwide. Its prevalence is predicted to rise further. Disappointingly, the treatments currently used are ineffective. There is an urgency to find new ways to counter this disease and one of the answers may lie in the ion channels belonging to the superfamily of TRP channels. In this review, we analyse the existing knowledge on the role of TRP channels in the development and progression of pancreatic ductal adenocarcinoma (PDAC). The functions of these channels in other cancers are also considered. This might be of interest for an extrapolation to the pancreatic cancer in an attempt to identify potential therapeutic interventions.

Neurophysiology goes wild: from exploring sensory coding in sound proof rooms to natural environments

To perform adaptive behaviours, animals have to establish a representation of the physical “outside” world. How these representations are created by sensory systems is a central issue in sensory physiology. This review addresses the history of experimental approaches toward ideas about sensory coding, using the relatively simple auditory system of acoustic insects. I will discuss the empirical evidence in support of Barlow’s “efficient coding hypothesis”, which argues that the coding properties of neurons undergo specific adaptations that allow insects to detect biologically important acoustic stimuli. This hypothesis opposes the view that the sensory systems of receivers are biased as a result of their phylogeny, which finally determine whether a sound stimulus elicits a behavioural response. Acoustic signals are often transmitted over considerable distances in complex physical environments with high noise levels, resulting in degradation of the temporal pattern of stimuli, unpredictable attenuation, reduced signal-to-noise levels, and degradation of cues used for sound localisation. Thus, a more naturalistic view of sensory coding must be taken, since the signals as broadcast by signallers are rarely equivalent to the effective stimuli encoded by the sensory system of receivers. The consequences of the environmental conditions for sensory coding are discussed.

TACHYCARDIA MISDIAGNOSED AS PSYCHOTIC MENTAL ILLNESS.

Many people with similar or related life challenges may decide not to share personal information of the kind described in the present memoir. My sharing is intended in defense of my cognitive salience: despite having been diagnosed as supposedly “psychotic.” It is my hope that this memoir might help tip the scales in favor of “psycho-social” rather than “in-your-head,” models of personality disorder (1, 2, 3). Superior psychological models can be found (4); even before the gross statistics of Charles Spearman (1863 to 1945), AND before the forced conditioning experimentations of Ivan Pavlov (1849 to 1936), AND as well before the dubious Oral-Anal Hypothesis of Sigmund Freud (1856 to 1939). Some of these models (4) were presented by names such as Francis Galton (1822 to 1911), Hermann von Helmholtz (1821 to 1894), and Wilhelm Wundt (1832 to 1920): leaders of the subject area-domains commonly referred to as Experimental Psychology and Sensory Physiology.

A New Apparatus for Recording Evoked Responses to Painful and Non-painful Sensory Stimulation in Freely Moving Mice

Experiments on pain processing in animals face several methodological challenges including the reproducible application of painful stimuli. Ideally, behavioral and physiological correlates of pain should be assessed in freely behaving mice, avoiding stress, fear or behavioral restriction as confounding factors. Moreover, the time of pain-evoked brain activity should be precisely related to the time of stimulation, such that pain-specific neuronal activity can be unambiguously identified. This can be achieved with laser-evoked heat stimuli which are also well established for human pain research. However, laser-evoked neuronal potentials are rarely investigated in awake unrestrained rodents, partially due to the practical difficulties in precisely and reliably targeting and triggering stimulation. In order to facilitate such studies we have developed a versatile stimulation and recording system for freely moving mice. The custom-made apparatus can provide both laser- and mechanical stimuli with simultaneous recording of evoked potentials and behavioral responses. Evoked potentials can be recorded from superficial and deep brain areas showing graded pain responses which correlate with pain-specific behavioral reactions. Non-painful mechanical stimuli can be applied as a control, yielding clearly different electrophysiological and behavioral responses. The apparatus is suited for simultaneous acquisition of precisely timed electrophysiological and behavioral evoked responses in freely moving mice. Besides its application in pain research it may be also useful in other fields of sensory physiology.

Fechner on a Walk

The Leipzig physicist Gustav Theodor Fechner (1801–88) is best known for his introduction of psychophysics, an exact, empirical science of the relations between mind and body and a crucial part of nineteenth-century sensory physiology and experimental psychology. Based on an extensive and close reading of Fechner’s diaries, this article considers psychophysics from the vantage of his everyday life, specifically the experience of taking a walk. This experience was not mere fodder for his scientific practice, as backdrop, object, or tool. Rather, on foot, Fechner pursued an investigation of the mind-body parallel to his natural-scientific one; in each domain, he strove to render the mind-body graspable, each in its own idiom, here everyday and there scientific. I give an account of Fechner’s walks as experiences that he both undertook and underwent, that shaped and were shaped by the surrounding everyday cacophony, and that carried a number of competing meanings for Fechner himself; the attendant analysis draws on his major scientific work, Elemente der Psychophysik (1860; Elements of Psychophysics), as the thick context that renders the walks legible as an everyday investigation. What results are three modes of walking—physiopsychical, interpersonal, and universal—each engaging the mind-body at a different level, as also engaged separately in Elemente’s three major sections, outer psychophysics, inner psychophysics, and general psychophysics beyond the human. This analysis ultimately leads to a new view of Fechner’s belief in a God who was “omnipresent and conscious in nature” and whom Fechner encountered daily on his walks in the budding of new blooms and rustling of the wind. More broadly, I aim to bring the analysis of everyday experiences as experiences into the historiography of science.

Molecular and Functional Characterization of Neurogenin-2 Induced Human Sensory Neurons

Sensory perception is fundamental to everyday life, yet understanding of human sensory physiology at the molecular level is hindered due to constraints on tissue availability. Emerging strategies to study and characterize peripheral neuropathies in vitro involve the use of human pluripotent stem cells (hPSCs) differentiated into dorsal root ganglion (DRG) sensory neurons. However, neuronal functionality and maturity are limited and underexplored. A recent and promising approach for directing hPSC differentiation towards functionally mature neurons involves the exogenous expression of Neurogenin-2 (NGN2). The optimized protocol described here generates sensory neurons from hPSC-derived neural crest (NC) progenitors through virally induced NGN2 expression. NC cells were derived from hPSCs via a small molecule inhibitor approach and enriched for migrating NC cells (66% SOX10+ cells). At the protein and transcript level, the resulting NGN2 induced sensory neurons (NGN2iSNs) express sensory neuron markers such as BRN3A (82% BRN3A+ cells), ISLET1 (91% ISLET1+ cells), TRKA, TRKB, and TRKC. Importantly, NGN2iSNs repetitively fire action potentials (APs) supported by voltage-gated sodium, potassium, and calcium conductances. In-depth analysis of the molecular basis of NGN2iSN excitability revealed functional expression of ion channels associated with the excitability of primary afferent neurons, such as Nav1.7, Nav1.8, Kv1.2, Kv2.1, BK, Cav2.1, Cav2.2, Cav3.2, ASICs and HCN among other ion channels, for which we provide functional and transcriptional evidence. Our characterization of stem cell-derived sensory neurons sheds light on the molecular basis of human sensory physiology and highlights the suitability of using hPSC-derived sensory neurons for modeling human DRG development and their potential in the study of human peripheral neuropathies and drug therapies.