Extracellular recordings reveal absence of magneto sensitive units in the avian optic tectum

Ramírez, Edgardo; Marı́n, Gonzalo; Mpodozis, Jorge; Letelier, Juan-Carlos

doi:10.1007/s00359-014-0947-6

Cited by 15 publications

(6 citation statements)

References 112 publications

(115 reference statements)

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“…Only if ferromagnetic components that are smaller than the magnetometer's spatial integration area are brought in close proximity to the specimen during stimulation, field inhomogeneities on scales below the spatial resolution of the sensor are to be expected. While purely analog AMR sensors were used in research on magnetoreception [16], the application of modern sensors with integrated analog frontend, A/D conversion, and digital data output, as presented here, greatly reduces the technological effort and thus facilitates the establishment of a robustly working system.…”

Section: Plos Onementioning

confidence: 99%

“…To date, only a few in vivo electrophysiological studies on the magnetic sense are available. Early extracellular recordings that detected magneto-sensitive neurons in the pigeon's optic tectum [15] turned out to be irreproducible in a technically well controlled replication study [16]. Cells in the vestibular brainstem of head-restraint pigeons exposed to sweeping magnetic field stimuli were found to encode magnetic field direction, intensity, and polarity [17].…”

Section: Introductionmentioning

confidence: 99%

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Integration and evaluation of magnetic stimulation in physiology setups

et al. 2022

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A large number of behavioral experiments have demonstrated the existence of a magnetic sense in many animal species. Further, studies with immediate gene expression markers have identified putative brain regions involved in magnetic information processing. In contrast, very little is known about the physiology of the magnetic sense and how the magnetic field is neuronally encoded. In vivo electrophysiological studies reporting neuronal correlates of the magnetic sense either have turned out to be irreproducible for lack of appropriate artifact controls or still await independent replication. Thus far, the research field of magnetoreception has little exploited the power of ex vivo physiological studies, which hold great promise for enabling stringent controls. However, tight space constraints in a recording setup and the presence of magnetizable materials in setup components and microscope objectives make it demanding to generate well-defined magnetic stimuli at the location of the biological specimen. Here, we present a solution based on a miniature vector magnetometer, a coil driver, and a calibration routine for the coil system to compensate for magnetic distortions in the setup. The magnetometer fits in common physiology recording chambers and has a sufficiently small spatial integration area to allow for probing spatial inhomogeneities. The coil-driver allows for the generation of defined non-stationary fast changing magnetic stimuli. Our ex vivo multielectrode array recordings from avian retinal ganglion cells show that artifacts induced by rapid magnetic stimulus changes can mimic the waveform of biological spikes on single electrodes. However, induction artifacts can be separated clearly from biological responses if the spatio-temporal characteristics of the artifact on multiple electrodes is taken into account. We provide the complete hardware design data and software resources for the integrated magnetic stimulation system.

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Section: Plos Onementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Integration and evaluation of magnetic stimulation in physiology setups

et al. 2022

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“…Accordingly, researchers in the field of magnetoreception agree that recording changes in a neuron’s current in response to a shifting magnetic field would confirm that cell’s magnetoreceptive properties (Lohmann and Johnsen 2000 ). Nevertheless, only a handful of studies report the use of electrophysiogical recordings in a bid to find the neuronal basis of magnetoreception (Beason and Semm 1987 ; Semm and Beason 1990 ; Lohmann et al 1991 ; Ramírez et al 2014 ; Cain et al 2005 ; Wang et al 2003 ; Wu and Dickman 2012 ; Walker et al 1997 ). For example, extracellular recordings within the ophthalmic branch of the trigeminal ganglia in vertebrates, such as rainbow trout, pigeons and bobolinks, revealed changes in spontaneous neuronal firing patterns in response to magnetic field changes (Beason and Semm 1987 ; Semm and Beason 1990 ; Walker et al 1997 ).…”

Section: Neural Correlates Of the Magnetic Sensementioning

confidence: 99%

Electrophysiology and the magnetic sense: a guide to best practice

2021

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Magnetoreception, sensing the Earth’s magnetic field, is used by many species in orientation and navigation. While this is established on the behavioural level, there is a severe lack in knowledge on the underlying neuronal mechanisms of this sense. A powerful technique to study the neuronal processing of magnetic cues is electrophysiology but, thus far, few studies have adopted this technique. Why is this the case? A fundamental problem is the introduction of electromagnetic noise (induction) caused by the magnetic stimuli, within electrophysiological recordings which, if too large, prevents feasible separation of neuronal signals from the induction artefacts. Here, we address the concerns surrounding the use of electromagnetic coils within electrophysiology experiments and assess whether these would prevent viable electrophysiological recordings within a generated magnetic field. We present calculations of the induced voltages in typical experimental situations and compare them against the neuronal signals measured with different electrophysiological techniques. Finally, we provide guidelines that should help limit and account for possible induction artefacts. In conclusion, if great care is taken, viable electrophysiological recordings from magnetoreceptive cells are achievable and promise to provide new insights on the neuronal basis of the magnetic sense.

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“…Electrophysiological responses to changes in magnetic directions were recorded from direction-sensitive cells in the nucleus of the basal optic root (nBOR), a part of the accessary optic system, and from the stratum griseum et fibrosum superficiale of the tectum opticum [69,70]. Yet recent studies failed to find magnetic field-induced activity in the tectum opticum [71,72].…”

Section: Magnetic Compass: Starting Out With Radical Pair Processesmentioning

confidence: 99%

Magnetoreception in birds

Wiltschko

2019

J. R. Soc. Interface.

104

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Birds can use two kinds of information from the geomagnetic field for navigation: the direction of the field lines as a compass and probably magnetic intensity as a component of the navigational ‘map’. The direction of the magnetic field appears to be sensed via radical pair processes in the eyes, with the crucial radical pairs formed by cryptochrome. It is transmitted by the optic nerve to the brain, where parts of the visual system seem to process the respective information. Magnetic intensity appears to be perceived by magnetite-based receptors in the beak region; the information is transmitted by the ophthalmic branch of the trigeminal nerve to the trigeminal ganglion and the trigeminal brainstem nuclei. Yet in spite of considerable progress in recent years, many details are still unclear, among them details of the radical pair processes and their transformation into a nervous signal, the precise location of the magnetite-based receptors and the centres in the brain where magnetic information is combined with other navigational information for the navigational processes.

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Extracellular recordings reveal absence of magneto sensitive units in the avian optic tectum

Cited by 15 publications

References 112 publications

Integration and evaluation of magnetic stimulation in physiology setups

Integration and evaluation of magnetic stimulation in physiology setups

Electrophysiology and the magnetic sense: a guide to best practice

Magnetoreception in birds

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