Graduate Student's Stuff Flashcards
Magnetoreception
Allows organism (birds) to detect magnetic field to perceive direction, altitude, or location.
Magnetoreception Theory 1: Upper Beak
Trigeminal Nerve filled with iron. 3 crystals on each side of the upper beak.
Magnetoreception Theory 2: Inner ear
Iron rich lagena organ/lagenal nerve. Iron rich.
Magnetoreception Theory 3: Retina
Birds that migrate at night need light availability and wavelength.
Magnetoreception support for upper beak.
Anesthesia/Lesion to trigeminal nerve disrupts magnetoreception.
Results of magnetic interference studies (birds in cages)
Magnetoreception support for inner ear.
increased firing when changes in magnetic field
Effects of inserting small magnets into inner ear and effects of lesions of lagena/lagenal nerve
Magnetoreception contradicting evidence for upper beak.
Magnetoreceptive cell organization.
Iron-rich cell identification
Other research has contradicting results.
Magnetoreception contradicting evidence for inner ear.
Iron content lower in lagena versus other organs.
Magnetic torque produced by lagena is weak.
Magnetoreception: RETINA: What is Radical pair mechanism? and Cryptochromes?
RPM: moving photons (photon absorption) from signlet to triplet states (radical formation)
Cryptochromes: respond to blue light, involved in circadian rhythm.
Magnetoreception retina support
cryptochromes generate radical pairs, drosophila lacking cryptochromes lose magneto receptive power, variation in cryptochrome activity.
Electroreception
ability to detect weak electrostatic fields. Used for communication, hunting, mating and navigation.
why is electroreception water only?
air resistivity is too high.
Electroreception: where is it, how does it evolve?
Ray have goo filled pores (tubes that lead to pouches, aka Ampullae of Lorenzini)
Evolved from lateral line mecahnoreception system.
Electroreception: circuitry
must have receptive organs that detect electrical differences. These are groups of sensory cells rooted in epidermal pits, which are innervated by cranial nerves.
Project to hypertrophied medullary nucleus. This is called electrosensory lateral lobe line (ELL). Electroreceptors have apical kinocilium and apical microvilli which make it similar to mechanoreception. Electric organs mostly have muscle cells.
Electroreception fill-in-the-blank:
____ is NT
___/___ ionotropic glutamate receptors in ELL.
______ cells in ELL express high levels of NMDARs and may play role in adaptive plasticity and feedback projections.
Ampullary receptors are most responsive to ________ fields.
Gluatmate
AMPA/NMDA
Pyramidal Cells
DC electric fields.