Final Study Flashcards
What does MOB stand for?
Main Olfactory Bulb
What does MOE stand for?
Main Olfactory Epithelium
What does AOB stand for?
Accessory Olfactory Bulb
What does VNO stand for?
Vomeronasal organ
What do OSN, OBP, OR stand for?
Olfactory Sensory Neurons
Odor Binding Proteins
Olfactory Receptors
What do PN and IN stand for?
Projection Neurons
Inhibition Neurons
What are some similarities between insect and mammal olfactory systems?
both have increased surface area in their olfactory organs from lining of tiny hairs (MOE in mammals and antennae in insects) (sensilla on antennae, hairs in nasal cavity)
most odorant receptors are G-protein coupled receptors
OSNs converge onto glomeruli in the brain (can receive input from different OSNs with the same OR type)
olfactory signals are sent from the glomeruli to higher brain centres for further processing
lateral inhibition from INs refine odor signals (increased sensitivity)
What are some differences between insect and mammal olfactory systems?
Mammals process olfactory information in olfactory lobes in their brains, insects have antennal lobes
mammals send olfactory signals from glomeruli to piriform cortex, amygdala, and hypothalamus; insects send to mushroom bodies and lateral horn for further processing
mammals send olfactory signals to brain centers via projection neurons called mitral and tufted cells; insects use other PNs
local interneurons increase specificity by lateral inhibition in insects; periglomerular and granule interneurons in mammals
What type of receptors are ORs?
typically G-protein coupled receptors that trigger intracellular signal cascades when activated
Describe the basic odorant pathway in mammals
odourant –> OBP –> MOE (4 zones) –> MOB (4 zones) –> Olfactory Tract –> amygdala, hypothalamus, piriform cortex
Describe the Olfactory Tract in mammals
the bundle of nerve fibers that serve as the main connection between the MOB and the higher order processing centers in the brain (no information processed, just relaying)
Describe the basic pheromone processing pathway in mammals
pheromone –> PBP –> VNO –> AOB –> medial amygdala –> hypothalamus
or
…. VNO –> epithelium –> basal to posterior AOB and apical to anterior AOB –> medial amygdala –> hypothalamus
Describe the signal cascade pathway of odourants in mammals
odourant –> OBP –> OR –> MOB but the pathway triggered is
OR –> GPCR –> Adenylyl cyclase –> cAMP increased –> cAMP-gated cation channel opens –> Ca++ and Na+ influx –> Ca++-gated Cl- channel opens –> Cl- out
Describe the signal cascade pathway of odourants in mammals in less than 1% of OSNs that occur in the MOE
Describe the signal cascade pathway of pheromones in mammals
pheromone –> PBP –> PRs –> AOB
pathway triggered is PR = GPCR –> Phospholipase C –> increase IP3 and DAG –> cation channel opens –> influx of Ca++ –> Ca++-gated Cl- channel opens –> Cl- out
What makes octopuses record breakers in their ability to learn, memorize, problem solve?
- large central brain and unsegmented, but highly specialized and distributed peripheral nervous system
- 2/3 of their neurons are in their arms = each arm is capable of processing sensory information, making decisions and executing motor actions independently from one another and from the brain = multi-tasking and problem-solving - high neural density = ~500 million neurons = advanced learning, memory and adaptability to environmental challenges
- multisensory processing in suckers on tentacles - high neural density in suckers for tactile, chemical and even light receptors - complex tasks like tool use for navigation
- learning and memory systems - have both short-term and long-term memory storage (vertical and superior frontal lobes) - recognize individuals, objects or retain info over time
- increased connectivity and faster communication of neurons - rapid transfer of information through en passant synapses
- division of labour is immense - 40 brain lobes that are highly specialized for vision, motor function, etc.
- neural plasticity - rapid rewiring of neural circuits in response to new challenges or environmental changes - trial and error learning, problem-solving
Which parts of the nervous system are involved in learning and memory in octopuses?
vertical and superior frontal lobes for long-term memory storage
What are en passant synapses? What do they do?
connections formed along the axons of neurons rather than at the terminal ends
they distribute neuronal signals more broadly - a single neuron can communicate with multiple targets simultaneously
= increased connectivity
= faster communication
= plasticity
= localized learning and processing without central brain input
Compare the Nautilus lifestyle and behaviour to Octopus
nautilus: nocturnal, sessile/slow-moving, jet-propulsion, gas chamber for buoyancy
octopus: active swimmers and hunters
Compare the Nautilus anatomy to Octopus
NAUTILUS:
- external shell secreted by mantle
- many tentacles without suckers
- pinhole eyes without cornea or lens
- nerve cord, unsegmented but segregated and specialized
OCTOPUS:
- no shell
- 8 tentacles with strong suckers
- funnel (modified foot)
- eyes with cornea and lens
- highly specialized ganglia with very large brain
Compare the Nautilus sensory structures and functions to Octopus
NAUTILUS:
- tentacles for chemosensory reception - prey and predator detection, feeding, sticking to substrates
- pinhole eyes (no cornea or lens): limited vision
OCTOPUS:
- complex eyes with cornea and lenses: vision with resolution similar to vertebrates
- suckers and mouth have chemoreceptors - detect prey (taste and smell)
- suckers have mechanoreceptors for navigating environment
- cristae and macula for orientation in 3D space (proprioception)
- chromatophores, reflecting cells, and photoreceptors on skin for camouflage
Compare the Nautilus camouflage to Octopus
both camouflage
NAUTILUS: counter-shading of shell
OCTOPUS: active camouflage - behavioural, muscular (skin texture), and colour camouflage
What is the updated definition of the Eimer’s organ in star-nosed moles? how many appendages make up the star?
the domed epidermal sensory organ that is made up of a central cell column (CCC), Merkel cells, encapsulated corpuscles, and 2 circles of free-nerve endings (one in CCC for texture detection and one in peripheral circle for nociception)
11 appendages make the star
What 4 types of cells make up the Eimer’s organs?
CCC - central cell column
1. Merkel cells - CCC
2. encapsulated corpuscles - peripheral
3. 2x free nerve endings - one for texture (CCC) and one for nociception (peripheral circle)