Olfactory system and amydala

Question 1

how is olfaction mediated?

Answer 1

mediated by receptors contained in olfactory epithelium which project directly to telencephalon.

Question 2

are olfactory neurons replaced threw life? if so, why?

Answer 2

Olfactory neurons replaced through life–>use large number of G protein -coupled receptor proteins able to detect wide range of odors.

Question 3

how do we smell an odorant?

Answer 3

ODORANT

• -> ODORANT BINDING PROTEIN (in mucus water film)
• ->STIMULATION OF CHEMOSENSITIVE CILIA

Question 4

what forms Cranial nerve 1?

Answer 4

axons of olfactory receptor neurons

Question 5

what forms the olfactory fila?

Answer 5

unmielinated axons of olfactory receptors

Question 6

what happens to the olfactory fila?

Answer 6

pass through holes of cribriform plate of ethmoid bone

–> end in olfactory bulb.

Question 7

what are mitral cells?

Answer 7

Specialized neurons in olfactory bulb

Question 8

what do mitral cells form?

Answer 8

form apical dendrites that receive synaptic contact from axons of primary sensory cells.

Question 9

dendrites + synapsis make up ________

Answer 9

olfactory glomeruli.

Question 10

axons of mitral cells form _______

Answer 10

olfactory tract.

Question 11

the olfactory bulb also contains interneurons, what are they called?

Answer 11

granule cells + tufted cells

Question 12

what are granule cells + tufted cells, and what do they do?

Answer 12

smaller than mitral cells, also send their dendrites into glomeruli + their axons into olfactory tract

Question 13

what is the main projection pathway?

Answer 13

LATERAL OLFACTORY TRACT, ending in UNCUS

Question 14

Axons of mitral cells send collaterals to the ______

Answer 14

anterior olfactory nucleus

Question 15

after axons of mitral cells send collaterals to anterior olfactory nucleus : __________________________

Answer 15

within olfactory tract –> fibers from anterior olfactory nucleus project back to both olfactory bulbs.

Question 16

Some fibers from anterior olfactory nucleus ________

Answer 16

end in anterior perforated substance (olfactory tubercle).

Question 17

what does the olfactory bulb directly project to?

Answer 17

olfactory cortex, bypassing thalamus (before reaching the cerebral cortex)

Question 18

what is the olfactory cortex?

Answer 18

a group of structures defined by connectivity, namely, structures that receive axons from the olfactory bulb

Question 19

what does the olfactory cortex contain?

Answer 19

piriform cortex= cortex adjacent to lateral olfactory tract
periamygdaloid cortex= cortex covering part of amygdala.
anterior part of parahippocampal gyrus.

Question 20

Cortixes which are part of the primary olfactory cortex project into 2 structures, which ones?

Answer 20

limbic structure : hypothalamus, amygdala, hippothalamus
Thalamus (dorsomedian nucleus): involved in pathway from olfactory bulb to olfactory association areas. (posterior part of frontal lobe orbital surface)

Question 21

what is the amygdala?

Answer 21

a collection of nuclei

Question 22

where is the amygdala?

Answer 22

beneath uncus of temporal lobe, at the anterior end of hippocampal formation, inferior horn of lateral ventricle

Question 23

what does the amaygdala do?

Answer 23

merges with periamygdaloid cortex, which forms part of surface of uncus.

Question 24

what processes is the amygdala involved in?

Answer 24

involved in emotional behaviors.

plays a critical role in linking external stimuli to defense responses.

Question 25

what does the electrical stimulation of amygdala in humans lead to?

Answer 25

feelings of fear + apprehension.

Question 26

What does fear conditioning in humans results in?

Answer 26

increased blood-oxygen-level-dependent (BOLD) signal in amygdala

Question 27

how is the amygdala usually assessed?

Answer 27

functional magnetic resonance imaging (fMRI)

Question 28

Recognition of emotional expression in faces involves ______

Answer 28

the amygdala

Question 29

Amygdala nuclei are divided into 3 groups:

Answer 29

o deep or basolateral group o superficial or cortical-like group o centro-medial group

Question 30

what does the centro-medial group of nuclei include?

Answer 30

medial + central nuclei.

Question 31

what does the superficial or cortical-like group group of nuclei include?

Answer 31

includes cortical nuclei, nucleus of lateral olfactory tract;

Question 32

what does the deep or basolateral group group of nuclei include?

Answer 32

includes lateral nucleus, basal nucleus, accessory basal nucleus;

Question 33

a separate set of nuclei that do not easily fall into any of these 3 groups is listed separately:

Answer 33

intercalated cell masses + amygdalo-hippocampal area.

Question 34

different nuclei of the amygdala divided into

Answer 34

``` into imput nuclei (receiving information) output nuclei (sending efferet) ```

Question 35

what is the basolateral group?

Answer 35

an input group

Question 36

What is the lateral nucleus (LA) typically viewed as?

Answer 36

as sensory interface of amygdala + key site of plasticity

Question 37

convergence of inputs is important in the amydala, why?

Answer 37

allows the generation of learned emotional responses to a variety of situations

Question 38

Sensitive information from different parts of central nervous system arrives to the amygdala from: (4)

Answer 38

Thalamus: Sensory Cortex: Hippocampus Others

Question 39

How does the aygdala receive information from the hippocampus?

Answer 39

(receives visual information fromV4, involved in object/face recognition pathway-V5, link in movement recognition pathway

Question 40

How does the amygdala receive information from other structures?

Answer 40

Inferior colliculus, Coeruleus nucleus, Solitary nucleus, Spinal cord , Association cortical areas including: orbital prefrontal cortex (negative drive…), insula (emotional evaluation of pain), Basal nuleus of Meynert: cholinergic projection of nucleus facilitates cortical activity in context situations having negative valence --> all pass through BASO-LATERAL NUCLEI

Question 41

How does the amygdala receive information from the thalamus?

Answer 41

(rapid and crude) (Lateral geniculate nucleus, Medial geniculate nucleus, VPL)

Question 42

what does the amygdala project to?

Answer 42

cerebral cortex + hypothalamus

Question 43

what is the output nucleus of the amygdala

Answer 43

CENTRAL NUCLEUS --> receives direct + indirect projections from LA (lateral nucleus)

Question 44

amygdala makes extensive connections with brain stem areas involved in _____________

Answer 44

the control of emotional responses

Question 45

the amygdala also projects to the _________

Answer 45

NUCLEUS BASALIS, which projects widely to cortical areas.

Question 46

cholinergic projections from nucleus basalis to cortex have been implicated in _______

Answer 46

cortical arousal.

Question 47

what is the stria terminalis?

Answer 47

C-shaped bundle travelling within thalamo-striate groove

Question 48

what does the stria terminalis do?

Answer 48

it separates the caudate nucleus + thalamus conveying efferent fibres from the amygdala to septal area + hypothalamus.

Question 49

what is the ventral amygdalofugal pathway?

Answer 49

Bundle of fibres running transversely in basal forebrain + connecting amygdala with hypothalamus, thalamus, brainstem.

Question 50

what does the PFC do?

Answer 50

o governs executive control of information processing + behavioral expression, including ability to selectively attend + maintain information o inhibits irrelevant stimuli + impulses o evaluates + selects appropriate response

Question 51

From the central nucleus, there are 2 pathways the information can take. What are their names?

Answer 51

* Ventral amygdalofugal pathway | * Stria terminalis