Pheromone Processing - Invertebrates

Question 1

Describe the CNS of arthropods

Answer 1

Dorsal anterior brain (pair of fused ganglia)
Ventral nerve cord with segmental ganglia

Question 2

Describe the PNS of arthropods

Answer 2

2-4 pairs of lateral nerves for each ganglion

Question 3

Where is the principle centre for motor control in arthropods?

Answer 3

The subesophageal ganglion

Question 4

What is the most telling property of an odorant or pheromone which determines where in the brain it will be processed?

Answer 4

Carbon chain length

Question 5

What are the 3 kinds of sensilla?

Answer 5

Trichoid (hairlike)
Basiconic (peglike)
Coeloconic (recessed peglike)

Question 6

How do pheromones access underlying OSNs of the sensillum?

Answer 6

There is a pore at the end of the sensillum

Question 7

Why do pheromones or odorants need pheromone binding proteins?

Answer 7

Need to cross the lipophilic barrier of the sensillum

Question 8

At the level of an OSN, how many synapses away from the CNS are we?

Answer 8

One

Question 9

How many unique ligand types is an OSN capable of binding?

Answer 9

1

Question 10

Some OSNs are capable of sensing (1) information in addition to chemosensory information

Answer 10

Mechanosensory

Question 11

The glomeruli of the antennal lobe are made of this substance

Answer 11

Neuropil

Question 12

Where is convergence of information happening during sensory processing of pheromones?

Answer 12

At the level of the glomerulus

Question 13

How does convergence of information increase sensitivity to a ligand?

Answer 13

Increases the redundancy of information reaching the brain

Question 14

What is a macroglomerular complex?

Answer 14

A glomerulus which is enlarged and deals with important pheromones

Question 15

What are the lateral and medial tracts of projection neurons?

Answer 15

Projection neuron tracts which go from the antennal lobe all the way to the mushroom bodies - 2 different pathways carrying information from one brain area to the next

Question 16

Where are Kenyon cells located?

Answer 16

In the mushroom bodies

Question 17

What is contained within the mushroom body calyces?

Answer 17

The dendritic fields of Kenyon cells

Question 18

How can the area of the mushroom bodies be increased?

Answer 18

Some insects have folds in the calyces for increased volume

Question 19

Where are the 2 synapses in pheromone processing in invertebrates?

Answer 19

1st: Between OSN and PN in glomerulus of antennal lobe
2nd: Between projection neuron and Kenyon cell in calyces of mushroom bodies

Question 20

As dosage of pheromone increases, so does (1) in OSNs

Answer 20

Frequency of action potentials

Question 21

At the level of the OSN, stimulus is encoded by (1), not (2)

Answer 21

Firing rate, not timing or temporal patterning of spikes

Question 22

At the level of the antennal lobe, the rate code of OSNs ins converted to…

Answer 22

Temporal code: which glomeruli are activated and when

Question 23

Stimulus at the level of the projection neurons of the antennal lobe is modulated by…

Answer 23

Local inhibitory neurons (release GABA)

Question 24

Information from all activated glomeruli of the antennal lobe is combined, a process known as…

Answer 24

Summation

Question 25

Projection neurons receive input from (2)

Answer 25

OSNs and LNs

Question 26

Where are the N and C termini of olfactory receptors in invertebrates?

Answer 26

N termini = intracellular
C termini = extracellular

Question 27

What are the 2 parts to an odorant receptor in inverts?

Answer 27

Specific part (OR) and General part (Or83b)

Question 28

Describe how odorant receptors can use ionotropic and metabotropic pathways

Answer 28

Receptor itself acts as an ion channel (ionotropic) and also uses G prot > AC > cAMP > CNG > depolarization

Question 29

What is the metabotropic pathway used by odorant receptors in invertebrate olfaction?

Answer 29

GDP converted to GTP on G-protein > AC activated > AC increases cAMP > cAMP opens CNG channels > cation influx