Lecture 18 - Olfaction and Limbic System Flashcards
1) What is the olfactory system involved in?
2) What receptors are used?
3) What are the First order neurons? route?
4) What are the second order neurons? route?
5) What are the layers of olfactory bulb?
1) olfaction (smell)
2) bipolar cells in olfactory epithelium within upper nasal cavity (on cilia)
3) receptor cells (bipolar olfactory nuerons) –> nonmyelinated axons –> bundle to form olfactory nerve –> penetrate cribiform plate of ethmoid bone –> enter olfactory bulb
4) mitral cells in olfactory bulb –> axons form olfactory tract
5) glomerular layer = olfactory nerve fibers synapse on dendrites of mitral cells
mitral cell layer and granule cell layer
6) Where does olfactory tract lead to?
7) There is lots of convergence on olfactory bulb, what does this lead to?
8) What are damaged neurons replace with here?
9) What do basal cells do?
6) olfactory tract bifurcates into medial and lateral olfactory stria
olfactory tract –> medial olf stria –> septal area (olfactovisceral reflexes) + hypo
olfactory tract –> lateral olf stria –> piriform cortex
(conscious awareness of smell - bypass thalamus)
7) increased sensitivity
8) basal cells
9) divide to produce new olfactory neurons
1) Summarize olfactory pathways
2) Describe signal transduction of olfaction
1) olfactory receptor neurons –> olfactory bulb
–> piriform lobe (consciuos perception of smell)
–> hypo and amygdala (motivation and emo aspects of smell)
–> hippocampus (odor memory)
2) Odor molecules –> membrane receptors (cilia) –> activation of G protein cascade –> cAMP –> activate Na+/Ca+ channels (in) and Cl- channels (out) –> membrane depolarization –> electrical response of sensory neuron (AP)
1) What are the basic units of odor info?
2) How do we detect distinct scents?
1) epitopes of odorant mols interacting with specific sites of distinct receptors
2) various epitopic sites of odor mols are mapped into activation of distinct subpop of olfactory neurons –> activation of characteristic comb of glomeruli in olfactory bulb –> olfactory cortex –> perception of distinct scents
1) Limbic refers to what?
2) Limbic structures are simply involved in what?
3) limbic structure surrounding brainstem + what = Limbic System?
4) What are the fns of limbic system?
1) cortical structures which comprise system form a border around brainstem
2) emotions
3) hypo, thalamus and epithalamus
4) -emotions of importance to survival =
assoc with self preservatino –> escape, defense, feeding
assoc with species preservation –> territorial defense, courtship, mating
-prcoesses involved in learning and memory
1) What are the criteria for being included in limbic system?
2) components of limbic system?
1) -rich innervation (by axons containing indoleamine and/or catecholamine NTs
- low threshold for seizure activity
- direct or indirect connections to hypo
2) hippocampus, cingulate gyrus (above CC), amygdala (near septal region), septal area (near midline below CC), portions of thalamus, piriform lobe and mammillary bodies of hypo
1) T or F: some areas of brain are neither purely sensory nor motor but instead are modulatory
2) Limbic system represent which one?
3) It’s essential for what?
4) Complex behaviors are often directed toward what?
5) Hunger ex.
6) neocortex has what kind of effect on emo behavior? illustrated by?
1) True
2) modulatory systems
3) neural circuitry underlying complex behaviros
4) filling a primary need –> hunger, thrist, sleep
- diff types of emos and emo responses within limbic realm
5) blood sugar low –> feel hunger –> perceptual and modulatory processes respond –> focus brain sensory apparatus on stimuli relevant to feeding (survey environment for clues of prey - sight, sound, odor)
6) dampening; sham rage
1) What is sham rage?
2) What is it characterized by?
3) Why is it named that way?
1) a type of rage rxn that occurs after removal of cerebral cortex from cat/dog
2) lashing of tail, vigorous arching of back, cclawing and attempts to bite and autonomic responses
3) anger occurs spontaneously or triggered by mild tactile or non-noxious stimuli
1) Describe anatomy of hippocampus
2) Why important?
3) Damage to hippocampus results in?
4) T or F: hippocampus has a very high seizure threshold
5) Initial studying is processed where?
1) simple 3-layered cortical structuer (archicortex)
2) involved in associative learning and memory, particulary memory acquisistion or short term memory
3) time-de-pendent impairmetns in behavioral tasks described as associative or relational in nature (amnesia patients)
4) False - very low seizure threshold
5) hippocampus
1) What is the septum?
2) stimulation results in?
3) lesion results in?
1) peasure center –> small cortical area involved in variety of physiological and behavioral processes (emos, relief of fear, docile behavior and stress, autonomic regulation)
2) docile behavior and suppression of many autonomic responses
3) rage and aggressive behavior and triggering of many autonomic responses
1) What is the amygdala?
2) Where is it located?
3) stimulation results in?
4) lesion results in?
1) highly differentiated region, a basal nucleus invovled in variety of behavioral and regulatory fns (emo and memory, social behaviors - repro, fear and aggresion, modulation of autonomic and neuroendocrine systems)
2) near temporal pole of mammalian cerebral hemisphere
3) rage and aggressive behavior
4) docile behavior
1) stimulation of hypo results in?
2) pigs exposed to acute immobilization stress show what?
3) What does the thalamus do?
4) key concept of limbic structures?
1) interconnections with limbic structures –> produce similar behaviors of other limbic sites –> rage and aggression sites, cowering and docile sites
2) dramatic inc in noradrenaline and adrenaline in hypo
3) links limbic system to neocortex –> provide means by which sensory info can gain access to limbic system
4) ind limbic structures have certain fns however all work together to give rise to behaviors animal exhibits
1) what are clinical signs associate with damage to limbic structures?
1) dullness
lethargy
sleepiness
stupor or semicoma
dementia
failure to recognize owners or familiar env
inability to learn
destructive behavior
irritability or aggressiveness
propulsive pacing or circling
1) Alzheimers involves atrophy of what?
2) results in?
3) Comb of amygdala and hippocampus helps with what?
1) hippocampus - one of 1st brain regiosn to suffer damage
2) memory problems and disorientation
3) remembering traumatic events (further solidified by stress hormone)
