-Olfactory receptor family (GPCRs)

-TAAR (trace-amine-associated receptor)

-V1R

-V2R

formyl-peptide-like

-main olfactory epithelium

-olfactory bulb

-nuclei of the primary olfactory cortex

-neocortex (perception of smell)

-vomeronasal organ

-accessory olfactory bulb

-medial amydgala

-limbic system

-hypothalamus (initiation of social behaviour)

-GPCR

-activation of a nucleotide cyclase

-cAMP or cGMP

-cyclic nucleotide gated channels

-GPCR

-phospholipase C activation

-PIP2 into IP3 and DAG

-IP3 opens CA++ channels

importance of TRPC2

What happens without it?

-normal mating behaviour

-no agression between males

-males cannot distinguish males from females

-territory marking

-colony identification

-social hierarchy

-reproductive status

-sex attractants

-mating rituals

-suppression or prolongation of estrus cycles of mature mice

-happens when females are housed together and isolated from males

estrogen-dependent pheromone that is released in the urine and acts on the VNO

-lowers concentration of LH and elevates prolactin levels.

synchronization of ovulation in a group of anoestrous female animals in the presence of a novel, sexually matured male of the same species.

-elevation of LH

induction of first estrous cycle in prepubertal female mice as a result of exposure to the urine of a sexually mature male.

-release of GnRH, which provokes first estrus

-opposite effect has been observed with exposure to mature female mouse

-important for finding a host for blood-sucking insects

-quality signal in plant feeding insects

-elevated CO2 concentrations causes fanning behaviour in bees

-global warming

-located in 4th ventricle

respond to pH of CSF

-regulate breathing

-carodit sinus (where carotid artery splits into external and internal carotid artery)

-aortic arch (aortic bodies)

both project to respiratory centers in the brain

active in rats in mice, but a pseudogene in primates

used to sense changes in CO2 concentration

project to necklace glomeruli

two gustatory receptors expressed in the cells that project to the V glomerulus

-other receptors located in nearby cells

-important molecules are GR63 and GR21

-URX neurons detect increases

-BAG neurons detect decreases

pancreas cells in the islet of langerhans

modified epithelial cells

they are not neurons

mainly located on the dorsal surface of the tongue

also found on the pharynx and palate.

There are a few in the nose and stomach

cells that express proteins involved in the initial events of chemosensory transduction, such as taste GPCRs, Ga gustudin, PLC-beta-2, and TRPM5

-dendritic process reaches surface of epithelium

-microvilli increase contact area. receptor molecules are concentrated on microvilli.

-dendrite and soma covered with multitude of channels

-"synaptic side" transmits information on sensory neurons but has no typical synapse structures

High sodium concentration causes it to enter cells and depolarize.

channel: epithelial - Na - channel "ENaC"

Decreased pH causes a Ca2+ influx in some cells.

most likely, H+ blocks K+ channel

sugars

amino acids

aspartame

alcohols

LiCl, KCl, lead chloride

sucrose increases cGTP and cAMP

bitter decreases cAMP levels

functioin is not clearly understood

-odors sensed by olfactory receptor neurons

-neurons project along antennal nerve to antennal lobe glomeruli, where they are sorted

-information is relayed by projection neurons in inner and medial antennocerebral tract to mushroom body and lateral horn

specific odor-response profile

only in olfactory receptor

insects express ubiquitous co-receptor, necessary for localization of olfactory receptor in osn dendrites

all osns expressing the same receptor project to the same glomerulus in the antennal lobe

~50 per antennal lobe

OSNs synapse with projection neurons, inhibitory local interneurons, excitatory local interneurons

complex output pattern for each odorant

most connect to mushroom bodies then go into lateral horn via inner antennocerebral tract

some connect to lateral horn directly via medial antennocerebral tract (bypass mushroom bodies)

lateral horn allows identification of odorants that is not influenced by experience

mushroom body allows learning, integration between modalities, experience dependent outcomes

-negative unconditional stimuli activate dopaminergic neurons

-present in mushroom bodies

-direct stimulation of DA neurons leads to avoidance of odorants presented at the time

-positive stimuli activate octopaminergic neurons (OA)

-taste receptors project into subesophageal gangleon.

-in bees, the VUM1 neuron goes from subesophageal ganglion to mushroom bodies

-Mutated OA flied cannot learn reward paradigm

alarm signal

health of others

solitary chemosensory cells

target is the trigeminal nerve

sense general odor ligands and CO2