B7.067 Limbic System

Question 1

taste (gustatory)receptor structure

Answer 1

taste buds line the circumvallate papilla

located in a row at the base of the tongue

Question 2

structure of taste bud

Answer 2

taste pore open to environment with saliva
on opposite end of bud are sensory cells which carry signal to the CNS via neurotransmitters
supportive cells located in between
basal cells located at the base of the taste bud by the receptor cells

Question 3

basal cell function

Answer 3

have regenerative capacity to generate new taste bud receptor cells

Question 4

transduction classes of tastants

Answer 4

1. directly ionic

2. second messenger

Question 5

directly ionic tastants

Answer 5

salty (Na+)
sour (H+)
changes membrane potential of cell directly

Question 6

second messenger tastant

Answer 6

sweet
bitter
umami
G protein couples receptor sets cascade in motion
end result of cascade is to depolarize cell and release neurotransmitters

Question 7

central gustatory pathways

Answer 7

1. receptors on tongue respond to stimulation
2. cranial nerves VII, IX, and X carry information
3. sensory afferents synapse in the solitary nucleus of the medulla oblongata
4. axons of postsynaptic neurons enter the medial lemniscus
5. axons synapse in the thalamus and project to the gustatory cortex

Question 8

olfactory receptor structure

Answer 8

olfactory epithelium consists of a layer of olfactory receptor cells, supporting cells, and basal cells
odorants dissolve in the mucus layer and contact the cilia of the olfactory cells
axons of the olfactory cells penetrate the bony cribriform plate on their way to the CNS

Question 9

regenerative capacity of olfactory receptor cells

Answer 9

one of the only parts of the brain that can undergo neurogenesis in adulthood
axonal pathfinding associated with new neurons working up to the CNS

Question 10

olfactory transduction

Answer 10

G protein coupled

receptor neurons express receptors for many olfactants

Question 11

primary secondary cells of the olfactory bulb

Answer 11

olfactory cells synapse in glomeruli with:
-mitral cells
-tufted cells
travel to olfactory areas of the CNS

Question 12

where does the olfactory tract project

Answer 12

NOT to the thalamus, no synapse
1st projection spot: piriform and periamygdaloid cortex
olfactory tubercle
amygdala
entorhinal cortex
contralateral olfactory bulb

Question 13

conscious odor perception pathway

Answer 13

olfactory bulb > piriform cortex > neocortex (orbitofrontal cortex)

Question 14

amygdala olfactory pathways

Answer 14

olfactory bulb > amygdala > septal nuclei OR hypothalamus

Question 15

hippocampal olfactory pathways

Answer 15

olfactory bulb > entorhinal cortex > hippocampus

Question 16

anosmia

Answer 16

loss of olfactory sense

Question 17

functions of the limbic system

Answer 17

homeostasis
olfaction
memory
emotions and drives

Question 18

structure of cortical limbic structures

Answer 18

more primitive cortical architecture

fewer than 6 layers

Question 19

neocortex

Answer 19

six layered cortex

majority of cerebral cortex

Question 20

mesocortex

Answer 20

limbic cortex
forms gradual transition between 3 and 6 layered cortex
ex: parahippocampal gyrus, cingulate gyrus, anterior insula, orbitofrontal cortex, temporal pole

Question 21

allocortex components

Answer 21

archicortex
paleocortex
cortex with fewer than 6 layers

Question 22

archicortex

Answer 22

3 layered hippocampal cortex

Question 23

paleocortex

Answer 23

3 layered olfactory cortex

piriform cortex

Question 24

Papez circuit

Answer 24

association and cingulate cortices > (cingulum) > entorhinal cortex > (perforant pathway) > hippocampal formation > (fornix) > mammillary body > (mammillothalamic tract) > anterior nucleus of thalamus

Question 25

input to the hippocampus

Answer 25

cells from entorhinal cortex synapse on dentate gyrus

Question 26

dentate gyrus

Answer 26

3 layers (from outside to inside)
molecular layer
granule cell layer
polymorphic layer

Question 27

granule cell layer

Answer 27

undergoes neurogenesis in adult life

rate altered by stress

Question 28

output of hippocampus

Answer 28

pyramidal cells to fornix

pyramidal cells further from dentate nucleus more susceptible from hypoxia

Question 29

other functions of the hippocampus

Answer 29

brain’s GPS

grid cells in the entorhinal cortex generate a grid map of the environment and interact w place cells

Question 30

limbic system region responsible for emotion and drives

Answer 30

the amygdala

Question 31

function of the amygdala

Answer 31

subconscious evaluator of the meaning of stimuli
emotional response to consequences of a situation
makes decision based on the reward value of stimuli

Question 32

functional regions of the amygdala

Answer 32

corticomedial nuclear group
basolateral nuclear group
central nucleus

Question 33

corticomedial nuclear group

Answer 33

input: olfactory system
output: hypothalamus, septum
function: feeding, repro

Question 34

basolateral nuclear group

Answer 34

input: temporal lobe (visual, auditory, tactile senses)
function: decision making

Question 35

central nucelus

Answer 35

input: brainstem (viscerosensory relay nuclei: solitary and parbrachial)
output: hypothalamus, brainstem
function: autonomic regulation

Question 36

centers involved in decision making

Answer 36

amygdala (basolateral nuclear group)
orbitofrontal cortex (OFC)
dorsolateral prefrontal cortex (DLPFC)
anterior cingulate cortex (ACC)

Question 37

fast thinking pathway

Answer 37

amgydala evaluates stimuli, sends output to executive cortical regions
situation > thalamus, visual, somatosensory, auditory, olfactory cortex > amygdala > orbito prefrontal cortex > lateral prefrontal cortex > decision

Question 38

dopaminergic pathways to the limbic system

Answer 38

modulation of exec function through the dopaminergic projection system
ventral tegmental areas (dopaminergic neurons) > nucleus accumbens > orbitofrontal cortex

Question 39

target of addictive drugs

Answer 39

nucleus accumbens

Question 40

dopaminergic projection systems

Answer 40

1. mesostriatal: “do”, basal ganglia
2. mesolimbic: “want”, limbic system
3. mesocrotical : “plan”, prefrontal cortex