Olfactory and Limbic Systems

Question 1

how many olfactory receptors are there

Answer 1

20 million per side

Question 2

are there synpses in the olfactory epithelium

Answer 2

no - receptors have axons which project directly to the olfactory bulb

Question 3

describe the olfactory receptor axons

Answer 3

thin, unmyelinated and slow

Question 4

olfactory receptors life cycle

Answer 4

60 days

Question 5

where are the first order neurons in the olfactory system

Answer 5

between receptors and the olfactory bulb

Question 6

what do second order neurons do in the olfactory system

Answer 6

synapse with tufted and mitral cells in the olfactory glomerulus

Question 7

what is the olfactory bulb formed from

Answer 7

unmyelinated axons of the tufted and mitral cells (bipolar neurons)

Question 8

what are the principle neurons of the olfactory bulb

Answer 8

mitral and tufted cells

Question 9

what do amoratic compounds do in the olfactory bulb

Answer 9

recognise particular receptors and travel to a particular golmerulus

Question 10

what are aromatic compounds

Answer 10

those which contain benzene rings

Question 11

what is the glomerulus

Answer 11

• basic processing component of olfactory bulb
• polysynaptic structure ensuring converion of specific olfactory synapses to the mitral and tuftal cells

Question 12

which mediate local and lateral inhibition

Answer 12

• periglomerular cells in the glomerulus
• granular cells in the deeper layer

Question 13

where is the olfactory tract found

Answer 13

in the olfactory sulcus

Question 14

what does the olfactory tract contain

Answer 14

axons of mitral and tufted cells

Question 15

where does the olfactory tract run to

Answer 15

olfactory trigone

Question 16

where does the lateral olfactory stria project to

Answer 16

olfactory cortex and parahippocampal gyrus (including uncus)

Question 17

what is the primary olfactory cortex also known as

Answer 17

the piriform cortex

Question 18

lateral olfactory stria function

Answer 18

conscious awareness of odour

Question 19

what are uncinate fits preceded by

Answer 19

hallucinations of disagreeable odours

Question 20

where does the medial olfactory stria project to

Answer 20

septal area

Question 21

medial olfactory stria function

Answer 21

olfacterovisceral reflexes

Question 22

where does the intermediate olfactory stria project to

Answer 22

olfactory tubercle

Question 23

intermediate olfactory stria function

Answer 23

reward behaviours

Question 24

which olfactory stria is the largest

Answer 24

lateral

Question 25

what does the anterior commissure do

Answer 25

connects two halves of olfactory system

Question 26

where is the anterior fissure found

Answer 26

anterior to the columns of the fornix

Question 27

where is the insula found

Answer 27

deep in sylvian fissure

Question 28

insula function

Answer 28

receives taste input from the medial part of the ventral posteromedial nucleus of the thalamus

Question 29

where is the orbitofrontal cortex found

Answer 29

base of the frontal lobe

Question 30

orbitofrontal cortex function

Answer 30

furthers conscious smell olfactory perceotion

Question 31

how does the libmic system operate

Answer 31

influences the endocrine system and the autonomic nervous system

Question 32

functions of limbic system

Answer 32

- controls emotions - mood - motivation - pain and pleasure sensations

Question 33

three cortical areas contained in limbic system

Answer 33

- septal area - cingulate gyrus - parahippocampal gyrus

Question 34

four deeper structures contained in limbis system

Answer 34

- hyppocampal formation and fornix - amygdala - mammillary bodies - anterior nuclei of the thalamus

Question 35

how are the limbic structures interconnected

Answer 35

by the papez circuit

Question 36

papez circuit components

Answer 36

- fornix - mammillothalamic tract - stria terminalis - cingulum

Question 37

hippocampus function

Answer 37

associative learning and memory

Question 38

what is caused by damage to hippocampus

Answer 38

amnesia

Question 39

where does the hippocampal formation project to

Answer 39

mammillary bodies of hypothalamus and spetal nuclei by way of fornix

Question 40

amygdala function

Answer 40

plays role in reproduction, fear and aggression and modulation of autonomic and neuroendocrine systems

Question 41

what do lesions to the amygdala cause

Answer 41

docile behaviour

Question 42

what does stimulation to the amygdala cause

Answer 42

rage

Question 43

kulver-bucy syndrome

Answer 43

- ignore social conventions - caused by bilateral lesions of anterior temporal lobe

Question 44

what is the amygdala connected to

Answer 44

- directly to thalamus - directly to neocortex - hypothalamus by stria terminalis

Question 45

septal area components

Answer 45

- septal nucleus - septum pellicudum - small portion of neocortex that forms part of limbic lobe

Question 46

what is the septum pellucidum

Answer 46

membrane between the two lateral ventricals

Question 47

what is the septal area connected to

Answer 47

hypothalamus and hippocamus (fornix)

Question 48

septal area functions

Answer 48

- relief of fear - docile behaviour - stress

Question 49

what do lesions to the septal area cause

Answer 49

rage and aggressive behaviour

Question 50

where is the cingulate gyrus found

Answer 50

overlying corpus callosum

Question 51

cingulate gyrus connections

Answer 51

- anterior nuclear group of thalamus by thalamic radations - hypothalamus by mammillothalamic tract

Question 52

cingulate gyrus function

Answer 52

control of emotional and visceral responses, agressive behaviour

Question 53

thalamus

Answer 53

- connects brainstem to cerebrum - relay centre - provides a means by which sensory information can gain access to limbic system

Question 54

hypothalamus

Answer 54

- Because of its interconnections with other limbic structures, stimulation of the hypothalamus produces many of the behaviours seen with the stimulation of other limbic sites - Stimulation reveals rage and aggression sites as well as docile behaviour

Question 55

what can acquired disorders of the limbic system cause

Answer 55

- violence - suicidal behaviour - agitation - mood swings

Question 56

neuropsychiatric disorders caused by damage to the limbic system

Answer 56

- anxiety - schizophrenia - psychopathic disorders