Animal Phys Lecture 11

What is photoreception?

Detection of light for vision.

What is PAX6?

A gene encoding a transcription factor for eye development.

When does PAX6 help initiate eye development?

During embryonic development.

What do pigment cells do in eyes?

Absorb light.

What two general eye types are compared?

Simple camera eyes and compound eyes.

Which animals are highlighted for compound eyes?

Insects.

What is an ommatidium?

A visual unit of a compound eye.

What is corneal refraction?

Bending of light at the cornea.

What happens to rays perpendicular to the cornea?

They are not bent at the surface.

What happens to rays striking the cornea at an angle?

They bend.

What does sympathetic activity do to pupils?

Dilates them.

When is sympathetic pupil dilation useful?

During fight-or-flight.

Which muscle name is associated with pupil constriction?

Sphincter pupillae.

What is lens accommodation?

Adjusting the lens to focus at different distances.

Which muscles are involved in accommodation?

Ciliary muscles.

What two ciliary muscle states appear in the slide?

Relaxed and contracted.

What is the choroid's function?

Supplies blood and nutrients.

What is the sclera's function?

Protects the eye and maintains its shape.

Which eye layer absorbs stray light?

Retinal pigment epithelium.

Which eye layer protects eye shape?

Sclera.

What are the two vertebrate photoreceptor types?

Rods and cones.

Which photoreceptors work best in low light?

Rods.

Which photoreceptors work best in bright light?

Cones.

Which photoreceptors provide high-acuity color vision?

Cones.

How many cone types are described for humans?

Three.

What is rhodopsin?

A visual pigment involved in light detection.

What does Gt stand for in the vision slide?

The GTP-binding protein transducin.

What does PDE stand for?

Phosphodiesterase.

What does cGMP stand for?

Cyclic guanosine monophosphate.

What is phototransduction?

Conversion of light detection into a cellular signal.

Why are rods especially light-sensitive?

More rhodopsin, amplification, and convergence.

What does greater signal amplification do?

Makes weak light signals easier to detect.

What is high convergence in rod circuits?

Many rods signal through fewer downstream cells.

Which downstream cells receive converging rod signals?

Bipolar and ganglion cells.

What is the tradeoff emphasized by cone circuitry in the fovea?

High spatial detail through near one-to-one connections.

What animal group has visual advantages emphasized in lecture?

Birds.

Which animals can detect UV patterns shown in the flower example?

Bees and birds.

Can humans detect polarization like specialized insects?

Not with the specialized vision described.

Which insects use polarized light for navigation?

Bees and ants.

Why is polarized light helpful when clouds cover the sun?

It still provides orientation cues.

Which animal inspired polarized-light camera research?

Mantis shrimp.

What is visual acuity?

Ability to distinguish details at a given distance.

What cone density is listed for humans?

About 38,000 cones per mm².

What is the macula?

Central retinal region for central vision.

What is the fovea?

A specialized high-acuity region within the macula.

Which receptors dominate the fovea?

Cones.

Which birds often have two foveae per eye?

Eagles, hawks, and falcons.

What is the function of the central nasal fovea?

Sharp vision of objects directly ahead.

What is the function of the temporal fovea?

Tracking objects from different angles.

Which predator and prey are used for visual-field comparison?

Snowy owl and American woodcock.

What is two-photon imaging?

Microscopy for observing neural activity in living animals.

Which animal is shown seeing moving stripes during imaging?

A fly.

What does DMD stand for?

Digital Micromirror Device.

What does a DMD contain?

Thousands of tiny movable mirrors.

What does a DMD do during neural imaging?

Directs light onto selected neurons.

What is SomArchon?

A genetically encoded voltage indicator.

What does SomArchon fluorescence report?

Changes in neuronal membrane voltage.

What rapid electrical events can SomArchon detect?

Action potentials or spikes.

What is calcium imaging?

Tracking neuronal activity via intracellular Ca²+ changes.

What happens after a neuron fires in calcium imaging?

Ca²+ enters the neuron.

What binds Ca²+ during calcium imaging?

A calcium indicator.

What detects the fluorescence change?

A microscope.

What is visual processing speed?

Time to recognize, analyze, and judge visual input.

What does CFF stand for?

Critical flicker fusion frequency.

What does higher CFF indicate?

Faster visual processing.