May 2012: This Month in JoVE

Abstract

The May issue of JoVE (Journal of Visualized Experiments) includes ahandful of articles that deal with the senses and perception.Specifically, articles involving gustation (taste), olfaction (smell),nociception (pain), and the vestibular senses (balance and inertialmovement) will be released.The vestibular system is important for perceiving inertial movement, andinertial information is an important component of path integration. Pathintegration is a process by which the brain integrates multisensoryinformation during movement, so that we maintain a sense of our body'sposition, relative to a starting point. In nature, many organisms makeuse of this process, in order to find their way back to their nests orburrows after looking for food.This May, JoVE will publish a method filmed at the Max Plank Instituteof Biological Cybernetics, which explores how path integration occurs inthree dimensions. Most studies of this phenomenon are conducted in twodimensions, but thanks to a motion simulator with a large range ofmotion, path integration can be assessed in the horizontal and verticalplanes. By controlling the sensory stimuli delivered to subjects in thisdevice, our authors can dissect the relative contributions of visual andinertial information to estimations of starting position.Through an elegantly designed series of experiments, these investigatorsfind that subjects are more likely to overestimate angles of movement inthe horizontal plane versus the verticals. They also find that subjectswere slower to point to the starting position when they had to rely onlyon inertial stimuli. The underlying neuronal mechanism behind pathintegration is poorly understood, and further experiments using thissystem will provide insight into how humans maintain spatial orientationduring movement, which has implications that range from understandingvestibular disorders and training better pilots.Concerning gustation, JoVE will publish a procedure for isolating andculturing human fungiform taste cells this May. Back in 2010, wepublished an article that dealt with isolation of human fungiformpapillae -a subtype of the tiny stuctures on our tongues that containtastebuds. While papillae collection is suitable for acute experiments,long-term studies of taste cells require them to be isolated andcultured.For the first time ever reported, our authors demonstrate the isolationand culture of human fungiform taste cells and show that they can bemaintained in culture for up to 8 passages, or one year. The ability toculture these cells for an extended period of time enables studies ofproliferation and regeneration, and obviates the need to repeatedlycollect papillae from donors.Regarding olfaction, JoVE will release an article from the Department ofAgriculture, which describes an experiment that transforms the antennaeof insects into a screening tool for new pesticide alternatives. Afterisolating plant volatile compounds via gas chromatography and massspectrometry, these investigators screen the compounds for biologicalactivity using the electroantennagram (EAG).Because not all of the volatile compounds emitted by plants elicitbiological responses, such a bioassay is incredibly important forfinding candidate molecules that can affect insect behavior. In turn,behavioral experiments, can determine whether or not a plant volatilecan attract an insect. Plant volatile attractants can be used to confuseinsects and potentially could serve as a safe alternative to pesticides.Thermal nociception, or the perception of noxious thermal stimuli, isthe focus of an article from the University of Texas this May.Specifically, thermal nociception is investigated in Drosophila larvaeusing two methods: the heat probe assay and the heat plate assay.Interestingly, for both methods, larvae must first be treated with UVradiation to induce tissue damage and sensitize thermal nociceptiveneurons, which usually respond with a very high threshold.As its name implies, the heat probe assay, uses a custom-built thermalprobe to locally administer thermal stimuli. Nociception is quantifiedby recording the latency between stimulus onset and withdraw behavior.Intuitively, the second method, or heat plate assay, involves placingdrosophila larvae on a heating plate within a drop of water to testwhole body responses to noxious heat. Upon placement, drosophila exhibita series of characteristic behaviors including rolling, whipping, oreven seizure-like activity. When combined with genetic manipulation,these assays can provide information about the genes underlying thermalnociception -a highly conserved process, from larvae to mammals.Naturally, an exploration of the senses is not all JoVE has to offerthis may. Other notable publications involve painting the pancreas tomaintain orientation during histology, using an automated operant deviceto test multi-cognitive functions in mice, examining tamoxifen-inducedapoptosis using timelapse video microscopy, and creating a convenienttool for fishing out lost samples from liquid nitrogen tanks. Staytuned.