lecture 4 LOs

Question 1

my/met and mesencephalon

Answer 1

house many of the cell bodies of neurons that use distinct NTs and send long projections that influence multiple brain regions

Question 2

basal ganglia

Answer 2

involved in motor controls and action selection

Question 3

most prominent nuclei in basal ganglia

Answer 3

dorsal striatum (caudate/putamen), and ventral striatum (nucleus accumbens)

Question 4

dorsal striatum key role

Answer 4

motor learning and action selection. recieves input from sensor/motor cortex and dopamine input from substantia nigra

Question 5

ventral striatum imp for

Answer 5

reward and motivated behavours
recieves input from limbic system and dopamine input from the ventral segmental area (mesencephalon)

Question 6

telencephalon limbic system

Answer 6

integrates emotional responses and regulates motivated beh and learning
in charge of the 4 Fs

Question 7

key regions o the telecephalon

Answer 7

hippocampus: associated with establishment of new long term memories and relational /spatial memory
amygdala: coordinates various components of emotional responses (esp fear) through profuse connections with other brain areas

Question 8

other areas considered part of limbic system

Answer 8

hypothalamus, nucleus accumbens, preforntal (cingulate) cortex

Question 9

most relevant region of cerebral cortex

Answer 9

frontal lobes. esp for many of the interesting actions of psychoactive drugs
brodmanns areas: partitioning of different cortical regions based on cytoarchitecture, or histological structure and organization of cells

Question 10

prefrontal cortex

Answer 10

critical for making decisions, planning actions, evaluating different strategies
this area is disrupted in many psychiatric disorders
also in frontal lobes: primary/secondary motor cortex that mediates voluntary and well learned motor sequences

Question 10

what is the PFC interconnected with

Answer 10

different nuclei in the limbic system and the striatum

Question 11

all telencephalon regions contain receptors for ___

Answer 11

numerous NT systems affected by psychoactive drugs

Question 12

three major types of synapses

Answer 12

axodendritic: terminal connects with a dentrite of the postsynaptic cell. most common type of synapse. synapses typically connect to dendritic spines, but occasionally connect to dendritic shafts
axosomatic: axon terminal forms connection with neuron cell body
axoaxonic: an exon synapsing on another axon terminal. can reduce (pre synaptic inhibition) or enhance transmitter release (presynaptic facilitation) of receiving terminal. work via heteroreceptors (receptor on axon terminal that responds to transmitters different from those released by those terminals)

Question 13

where are most transmitters made

Answer 13

in terminals, but peptides are made in soma and then transported to terminals

Question 14

where do many peptide transmitters reside

Answer 14

in terminals that also contain classical small molecule transmitters

Question 15

neuromodulators def

Answer 15

may enhance, reduce, or prolong the action of another NT
cannot easily be seen as excitatory or inhibitory, can have different effects depending on multiple factors

Question 16

volume transmission

Answer 16

neuromodulators may diffuse away from the site of release to influence other cells

Question 17

rate and pattern of neuron firing

Answer 17

in general, higher firing rates means more NT release
burst firing leads to release more transmitter than rapid cont firing
many neurons that use classical NTs (DA, NE, 5-HT(serotonin)) switch to burst firing modes in response to motivationally or emotionally relevant stimuli

Question 18

autoreceptors def

Answer 18

receptors for the same transmitter released by neuron

Question 19

autoreceptor presynaptic terminal activated and inhibited by

Answer 19

activated by NT, inhibit further transmitter release

Question 20

somatodendritic autoreceptors, where are they and what do they do

Answer 20

reside on cell bodies/dendrties when activated, they slow firing, reduces transmitter release

Question 21

drugs that block autoreceptors ___ transmitter release

Answer 21

increase

Question 22

drugs that stimulate autoreceptors ___ transmitter release

Answer 22

reduce

Question 23

transmitters can be removed from the synapse by

Answer 23

enzymatic degradation
being taken up by presynaptic neurons (reuptake)
reuptake by nearby glial cells (astrocytes)

Question 24

reuptake mediated through ___

Answer 24

transporter proteins
typically work via active transport
some transporters are sloppy and can uptake other types of NTs with similar chemical structure

Question 25

NTs have multiple receptor subtypes that can differ in:

Answer 25

expression of different subtypes can vary across and/or within brain regions
all subtypes bind some ligand, but may do so with different affinities
sometimes, different receptor subtypes can exert opposite cellular effects (via different 2nd messengers)

Question 26

two major categories of transmitter receptors

Answer 26

ionotropic: aka ligand gated ion channels
metabotropic: aka 2nd messenger or G-protein coupled recetors

Question 27

ionotropic receptors:

Answer 27

consist of 4 or 5 subunits with an ion channel in center
some conduct Na+: opening excites (depolarizes) neurons
others allow flow of Na+ and Ca2+. Ca2+ entry can depolarize neuron and act as a second messenger
others conduct Cl- leading to hhyperpolarization (inhibitory)

Question 28

metabotropic receptors:

Answer 28

act more slowly, effects last longer relative to ionotropic
work by activiating G proteins that act in one of two ways:
inhibit/activate ion channels (eg opens K+ channels, outflow causes hyperpolarization)
stimulate/inhibit effector enzymes that synthesize or break down second messenger molecules

Question 29

protein kinases

Answer 29

second messengers are molecules inside cell that activate protein kinases that phosphorylate other proteins
phosphorylation of ion channels/eceptors can change their function
phosphorylation of nuclear proteins can turn gene expression off

Question 30

second messenger pathway cyclic adenosine monophosphate (cAMP)

Answer 30

stimulates protein kinase A (PKA). some second messengers stimulate this pathway via a G-s protein), others inhibit cAMP (via G-i protein). controlled by some receptors for DA, NE, 5-HT (serotonin), endorphins

Question 31

phosphoinositide second messenger pathway

Answer 31

breaks down a phospholipid in cell membrane, liberates two second messengers: diacylglycerol (DAG) and inositol triphosphate (IP3). DAG and IP3 increase concentration of Ca2+ ions in postsynaptic cell and activate protein kinase C (PKC). controlled by receptors for ACh, NE, 5-HT (serotonin)