Deck 20: Walking, Flying, and Swimming: Cellular Mechanisms of Sensorimotor Behavior in Invertebrates

Question 1

Which of these is not an advantage to the use of invertebrates to study the neural basis of behavior?

A) Invertebrate behavior tends to be more consistent and replicable than that of most vertebrates.
B) The nervous system of many invertebrates is easier to access or observe than that of most vertebrates.
C) Behavioral functions are often controlled by a smaller number of neurons in invertebrates than in vertebrates.
D) The invertebrate brain has basically the same structure as that of vertebrates, but with fewer neurons.
E) All of the above are advantages of invertebrates.

Answer 1

D

Question 2

Which of the species below is studied because its relatively simple behaviors are controlled by a small number of easily observable, large neurons?

A) Leech
B) Honeybee
C) Cockroach
D) Desert ant
E) Giant squid

Answer 2

A

Question 3

The desert ant Cataglyphis bicolor uses this as a primary stimulus for navigating back to its nest after a foraging trip.

A) Pheromone trail
B) Visual landmarks
C) Polarized light
D) Directional cues from the stars
E) The odor of the nest

Answer 3

C

Question 4

The foraging trajectory of the desert ant Cataglyphis bicolor follows

A) a winding, meandering outward path, with a direct and rapid return.
B) a direct and rapid outward path, and a winding, meandering return.
C) a direct rapid outward and homeward path.
D) a path in the shape of a spiral or concentric circle.
E) short segments between one spatial landmark and the next.

Question 5

The text discusses the use of these navigational cues by honeybees.

A) Geomagnetic cues, polarized light, and a visual odometer
B) Olfactory cues, wind direction, and sun location
C) Wind direction, polarized light, and internal pedometer
D) Auditory cues from the hive, pheromones, and geomagnetic cues
E) Pheromones, sun location, and wind direction

Question 6

Imagine that a researcher sets up a tunnel through which a bee needs to fly in order to find a sucrose feeder. The inside of the tunnel is lined with a two-inch square black-and-white checker pattern. After the bee is accustomed to foraging here, the researchers do a test in which the tunnel is lined with an (otherwise identical) three-inch square black-and-white checker pattern, and the feeder is removed. Based on what you know about honeybee navigation, predict how the bee will likely behave.

A) It will search for food closer to the hive than the location of the original feeder.
B) It will search for food farther from the hive than the location of the original feeder.
C) It will search for food at approximately the distance of the location of the original feeder.
D) It will just keep flying through the tunnel without searching for food.
E) It will remain at the hive due to the unfamiliar stimulus.

Question 7

If a foraging bee is placed under a device that modifies the ambient magnetic cues, and the bee tries to orient to the south, the bee will

A) orient to the true south.
B) orient randomly.
C) orient to the modified magnetic south.
D) orient to the true south only if the sun is out.
E) fly in circles until it gets out from under the device.

Question 8

Ants are able to use the sun for navigation, despite its movement through the sky, by

A) using time of day to correct for the trajectory of the sun.
B) only traveling at the same time each day, to keep the sun consistent.
C) always orienting away from the sun for an outward trip, and toward the sun to get home.
D) using specialized ommatidia that orient toward the sun at all times.
E) foraging to the east in the morning, and to the west in the afternoons.

Question 9

How do foraging desert ants use landmarks or distinctive features of the terrain?

A) To mark and remember the "goal" location where food can be found
B) Primarily near the nest to pinpoint the location of the hole
C) Throughout the foraging trip as one of the primary navigational cues
D) As "sign posts" to mark where the path needs to turn or change
E) Not at all, because they are insensitive to landmark cues

Question 10

In addition to using polarized light to navigate, Cataglyphis can also use the following cues

A) Pedometer, pheromone trails, and star compass
B) Wind direction, terrain landmarks, and pheromone trails
C) Pedometer, wind direction, and sun location
D) Pheromone trails, geomagnetic field, and sun location
E) Star compass, geomagnetic field, and wind direction

Question 11

If a researcher were to place a dome over a navigating desert ant that filters polarized light as it travels, she would expect to see

A) a disrupted outward path, and no attempt to return home.
B) a normal outward path, but disruption in the homeward path.
C) normal navigation on both the outward and homeward path.
D) random wandering around the nest with no attempt to forage.
E) a longer outward trip than usual, and failure to compensate on the homeward path.

Question 12

If researchers were to place a frosted glass dome over a navigating desert ant that allowed light to pass through but prevented the ants from seeing the sun in the sky, they would expect to observe in the ants

A) a disrupted outward path and no attempt to return home.
B) a normal outward path but disruption in the homeward path.
C) normal navigation on both the outward and homeward path.
D) random wandering around the nest with no attempt to forage.
E) a longer outward trip than usual and failure to compensate on the homeward path.

Question 13

The sensitivity of an ant's visual system to the polarization of light is based on

A) stacks of microvilli with specific orientations.
B) ommatidia that face different directions.
C) two distinct photopigments that are sensitive to light polarized at different angles.
D) the fact that UV light looks different when it is polarized at different angles.
E) special cells that act as filters over some photoreceptors, blocking light polarized at specific angles.

Question 14

The location of the ant eye most sensitive to polarized light is the

A) center.
B) caudal region.
C) ventral edge.
D) dorsal rim.
E) frontal segment.

Question 15

If researchers were to damage the dorsal rim of the eyes of the desert ant, then observe its foraging behavior, they might expect to observe

A) a disrupted outward path and no attempt to return home.
B) a normal outward path but disruption in the homeward path.
C) normal navigation on both the outward and homeward path.
D) random wandering around the nest with no attempt to forage.
E) a longer outward trip than usual and failure to compensate on the homeward path.

Question 16

In order to determine direction using polarized light, an ant must be able to see

A) the sun, and its location in the sky.
B) the majority of the sky on a cloudless day (even if the sun itself is blocked).
C) the majority of the sky, even if it is overcast.
D) a small part of the sky that need not include the sun.
E) both the sun and an object reflecting the sun.

Question 17

Learning is required in order for ants to use these stimuli for navigation.

A) Odors that predict the location of food or the nest
B) How to use the location of the sun
C) How to discriminate between different orientations of light polarization
D) Visual landmarks that designate the location of food
E) Which pheromones predict food, and which predict other stimuli

Question 18

When ants are new to foraging, they maintain their orientation during "learning walks" by using these cues.

A) Light polarization
B) Geomagnetic cues
C) Nest odor
D) Pheromone trails
E) Internal pedometer

Question 19

The twisted rhabdomeres in certain ommatidia of the honeybee serve the function of allowing

A) the bee to perceive geomagnetic fields.
B) the bee to detect stimuli in multiple directions at once.
C) detection of the sun's location.
D) more accurate discrimination of light polarization.
E) more accurate color vision.

Question 20

The disadvantage of a visual receptor structure that responds selectively to polarized light is that

A) polarized light does not provide reliable directional cues.
B) polarized light depends on the location of the sun in the sky.
C) these receptors would be incapable of responding to the visible light spectrum.
D) color perception would depend on surface texture and direction of view.
E) these receptors could not function when the sky is cloudy.

Question 21

Neuroscientists have studied the mechanisms by which lobsters and crayfish are attracted to _______ and withdraw from _______.

A) dim light; bright light
B) darkness; light
C) light; darkness
D) blue wavelengths; red wavelengths
E) red wavelengths; blue wavelengths

Question 22

In the crayfish optic nerve, "sustaining" neurons respond to more intense light by

A) firing a train of action potentials at a higher rate.
B) firing a train of action potentials at a lower rate.
C) suppressing all firing activity.
D) producing short bursts of activity with a higher probability.
E) firing in an on-off pattern with a greater degree of synchrony.

Question 23

A command neuron is a specific type of neuron that coordinates

A) sequences of motor responses.
B) multiple modalities of sensory input (e.g., auditory and visual stimuli).
C) orientation of photo receptors toward visual inputs.
D) multiple input neurons to fire in synchrony.
E) travel vectors based on polarized light and an internal pedometer.

Question 24

A neuron that, when stimulated, produces a complete escape response from a stimulus, is most likely a(n)

A) somatosensory neuron.
B) command neuron.
C) ommatidium.
D) postganglionic neuron.
E) caudal neuron.

Question 25

Experiments with crayfish have demonstrated that direct illumination of these receptive fields tends to produce a withdrawal rather than a forward walking response.

A) Upper part of the eye and the tail
B) Upper part of the eye and the antennae
C) Lower part of the eye and the antennae
D) Lower part of the eye and the tail
E) Outer rim of the eye and the forelegs

Question 26

The mechanism by which a crayfish decides whether to approach or withdraw from illumination appears to be

A) Mutual inhibition of sustaining neurons.
B) Complex interconnections in the visual cortex.
C) Whether or not sustaining neurons are activated.
D) Motor neurons that propel the legs either forward or backward.
E) a switch neuron in the caudal ganglion.

Question 27

Sequences of rhythmic behavior, such as backward walking in the crayfish and swimming in the leech, rely on

A) the motor cortex section of the invertebrate brain.
B) repeated activity of the environmental stimulus that triggers the response.
C) specialized sensory receptors that detect body position.
D) specialized circuits called central pattern generators.
E) specialized motor neurons that innervate multiple muscle fibers.

Question 28

Compared to insect and crustacean models used in neuroscience, the leech has

A) about one-tenth the number of neurons and simpler behavior.
B) about the same number of neurons and simpler behavior.
C) about the same number of neurons but more complex behavior.
D) about one-tenth the number of neurons and more complex behavior.
E) about the same number of neurons but they are easier to map.

Question 29

Scientists began studying leeches

A) over 100 years ago, due to their widespread use in medicine.
B) in the 1960s with the advent of modern neuroscience.
C) in the early 2000s, when they were discovered for transgenic use.
D) in the early 2000s, when they were used to trace embryonic cells.
E) only recently, when their genome was sequenced.

Question 30

The central nervous system of the leech consists of

A) a brain near the head and a spinal cord.
B) a brain near the head and a tail ganglion.
C) one brain-like ganglion at each end and a large number of segmental ganglia.
D) one brain-like ganglion at each end and a central abdominal ganglion.
E) four equally-spaced segmental ganglia of similar size.

Question 31

One major strength of the leech as a model organism is the

A) central brain that acts as a switchboard for all sensory input and motor output.
B) large number of redundant neurons that produce strong field potentials.
C) variety of sensory systems that are comparable to those of humans.
D) consistency of identifiable neurons across ganglia and across individuals.
E) small size for housing in the laboratory.

Question 32

The segmental ganglia in the leech function by

A) relaying sensory information to the brain.
B) densely interconnecting with each other to form a network.
C) receiving motor commands from the brain and sending them to the correct destination.
D) independently receiving sensory input and controlling motor output to its segment.
E) None of the above

Question 33

In the leech, a central pattern generator (CPG) has been identified that is responsible for

A) chewing behavior.
B) antipredatory behavior.
C) annular erection (ridging of the skin).
D) swimming behavior.
E) the startle reflex.

Question 34

Motor neurons in the leech use this neurotransmitter to produce excitatory responses in muscle fibers.

A) Glutamate
B) Dopamine
C) Serotonin
D) Norepinephrine
E) Acetylcholine

Question 35

In the leech, AE neurons and L neurons, respectively, function to

A) detect light stimulation and strong stimulation of the skin.
B) detect chemicals related to food and those related to predators.
C) produce a skin-ridging response and a body-shortening response.
D) produce a body-shortening response and a swimming response.
E) facilitate habituation and sensitization.

Question 36

Connections between sensory and motor neurons in the leech employ

A) only electrical synapses.
B) chemical synapses including both ion channels and g-protein-coupled receptors.
C) primarily nicotinic receptors.
D) primarily glutamate as a neurotransmitter.
E) both chemical and electrical synapses.

Question 37

T, P, and N neurons in the leech respond to this type of stimulation.

A) Illumination (photosensory)
B) Touch (mechanosensory)
C) Vibration (auditory)
D) Chemicals (chemosensory)
E) Internal movement (proprioceptive)

Question 38

Very light pressure to the skin of a leech will produce activity in a

A) C cell.
B) P cell.
C) N cell.
D) T cell.
E) M cell.

Question 39

T, P, and N neurons in the leech differ by approximately this many expressed genes.

A) One
B) Fewer than ten
C) About one hundred
D) About five hundred
E) Over a thousand

Question 40

If an S-cell is damaged or prevented from transmitting signals, the result is that

A) habituation is intact but sensitization is impaired.
B) sensitization is intact but habituation is impaired.
C) both habituation and sensitization are impaired.
D) the reflexive response to touch is eliminated.
E) the reflexive response to touch is strengthened.

Question 41

The function of S-cells appears to involve

A) serving as a central pattern generator (CPG).
B) producing a reflexive shortening response.
C) serving as a command neuron.
D) modulating the degree to which L motoneurons are excited by sensory input.
E) producing a bending response away from skin stimulation.

Question 42

Habituation in the leech can be demonstrated by

A) repeatedly stimulating single L neurons with an electrode.
B) repeatedly touching the same body segment.
C) injecting long bursts of electric current into T neurons.
D) inducing the leech to move forward for an extended period of time.
E) injecting electric current into the segmental ganglia.

Question 43

Researchers induce habituation in two groups of leeches by repeatedly stimulating a section of skin on the leeches with a gentle stream of water. Following habituation, researchers use an electrode to stimulate a T cell (in Group 1) or an N cell (in Group 2) in a nearby part of the body. When subsequently stimulated with another gentle stream of water (in the original location), the researchers would likely expect to see

A) sensitization in both groups.
B) habituation in both groups.
C) habituation in Group 1, and dishabituation in Group 2.
D) dishabituation in Group 1, and sensitization in Group 2.
E) sensitization in Group 1, and habituation in Group 2.

Question 44

A researcher studying behavioral flexibility in the leech might expect to observe habituation after repeated stimulation of _______, and sensitization after repeated stimulation of _______.

A) S neurons; L neurons
B) photoreceptors; touch receptors
C) The skin; sensory neurons
D) N cells; T cells
E) T cells; N cells

Question 45

Serotonin (or 5-HT) levels in the leech have been linked to

A) swimming behavior.
B) eating behavior.
C) crawling behavior.
D) habituation.
E) sensitization.

Question 46

Select one of the invertebrate models described in your textbook, and explain two advantages of using that model for neuroscience research.

Question 47

Imagine that you are a researcher interested in identifying the neural mechanisms responsible for a simple escape response from a strong (noxious) stimulus. What model would you select, and why?

Question 48

Describe two stimuli that bees use to navigate through space.

Question 49

What are the advantages of using polarized light rather than simply the location of the sun in the sky for the purpose of navigation?

Question 50

Imagine that you are a researcher presented with a new species of ant that has not yet been studied. Your goal is to determine whether this new species can use polarized light to navigate in the same way as Cataglyphis bicolor. Describe one experiment that you would use to help answer this question.

Question 51

Describe one way that learning plays a role in spatial navigation in ants.

Question 52

What is the difference in structure and function between ommatidia in the dorsal rim of the bee eye, and in the other areas of the bee eye?

Question 53

What advantage do crayfish offer compared to ants and bees as subjects for the study of the organization of neuronal circuits?

Question 54

Explain how an illumination stimulus can lead sometimes to withdrawal and sometimes to approach in crayfish.

Question 55

What is a central pattern generator (CPG)?

Question 56

Describe two features of the leech structure that make it especially useful for investigating how individual neurons produce behavior.

Question 57

Explain the functions of the T, P, and N neurons in the leech.

Question 58

What are the three types of sensory neurons found in leech segmental ganglia?

Question 59

Explain the role of the S neuron in the leech.

Question 60

Explain how scientists induce habituation in the leech.