Lecture 2

Question 1

An article was covered in class and showed brain tissue growth-red and decrease-blue over time. What were the key takeaways from this? (4)

Answer 1

• see that brain is growing and increases in size until teen years
• also occurs in animals (but smaller volume)
• indicates that brain is growing and that this developmental process is ongoing
• the developmental processes are very susceptible to environmnetal stimuli

Question 2

what is neurogenesis?

Answer 2

formation of new neurons in the brain

Question 3

what article was provided in class as evidence for adult neurogenesis?

Answer 3

hippocampus and olfactory bulb in adult rodents

• controversy: is there really adult neurogenesis in adult humans?

Question 4

what were the conclusions of the article covered on learning and brain plasticity? (3)

Answer 4

• evidence that suggests that representation of hand digits can be modified by training
• comparing dipole strength of regions representating finger position and can be stored in string players
• if you use a finger more, its representation strengthens/increases

Question 5

how does allosteric load relate to the impact of chronic stress on our bodies?

Answer 5

• bc chronic stress can lead to long term increase of cortisol, this can induce changes in the brain that have pathological changes
• NE is responsible for acute stress responses (like flight or fight response) -> cortisol helps bring aroused state back to baseline
• if you have high level of cortisol due to stress, can have adaptation changes (that used to be healthy) that are maladaptive

Question 6

what is allostatic?

Answer 6

low allostatic load (also involved in brain plasticity)

Question 7

what results were shown to explain the relationship btw life events and mood disorders?

Answer 7

Negative life events near the onset of depressive episode

Negative life events associate with the severity of cognitive impairment of depression

Levels of cortisol in plasma and CRH in aCSF are increased in patients with depression

Question 8

When you compare the number of negative life events in months before an episode of depression, the trend is ____ for the general population while ____ for those with depression and suicide attempters

Answer 8

steady; increased

Question 9

explain the results of the following study (4):

Injected cortisol in rats to induce stress and compared the dendritic representations of CA3 in the hippocampus

Answer 9

• see more changes after chronic injections of cortisol –> see shrinking of dendrites in ca3
• these changes also found in aging –> suggests that chronic stress might make you age faster
• when they quantify the dendrites from the cell body, dendrites away from the cell body are shortened (reduce in length, size)
• if you remove cortisol/stress, the dendrites grow back (in rats) –> dynamic process

Question 10

what might stress induce for it to be a risk factor for mood disorders?

Answer 10

• using scans to measure brain volume in people with diff mental dx (ie dep)
• meta analysis supports findings of animal studies that theres a decrease in hippocampal volume in people with depression

Question 11

who were the subjects in the study on the impact of traumatic events (PTSD) on brain health?

Answer 11

1. ExP+ : combat exposed subjects WITH ptsd
2. UxP+ : co-twins of ExP+ with NO ptsd
3. ExP- : combat-exposed subjects with NO ptsd
4. UxP- : co-twins of ExP- with NO ptsd

Question 12

who were the 3 possible scenarios in the study on the impact of traumatic events (PTSD) on brain health?

Answer 12

1: ptsd is related to stress on hippocampus – expect those with ptsd to have smaller hippocampal volume

2: some genetic makeup causes smaller hippocampus to begin with – expect both twins (co-twin WITH and WITHOUT) to have smaller hippocampus

3: whether u have combat experience (independent of ptsd or not) you will have smaller volume

Question 13

what were the results of the study on the impact of traumatic events (PTSD) on brain health?

Answer 13

found similar relationship: even without experience of combat, size of hippocampus of twin can predict your vulnerability to ptsd
- second scenario is supported by findings

lower hippocampal volumes for twins with ptsd

Question 14

the presence of _____ factors –> more biological factors that could explain our vulnerability to stress

Answer 14

vulnerability

Question 15

what are characteristics of stress resilient mice?

Answer 15

1. lower HPA axis activity
2. higher exploration
3. lower anxiety
4. lower submissive behavior

Question 16

what are characteristics of stress resilient mice?

Answer 16

1. greater HPA axis activity
2. lower exploration
3. greater anxiety
4. greater submissive behavior

Question 17

what is early life stress?

Answer 17

Encompasses early traumatic experiences during childhood and adolescence

Question 18

what are the subtypes of ELS? (5)

Answer 18

emotional abuse, physical abuse, sexual abuse, emotional neglect, and physical neglect

Question 19

what are the symptoms of those who experienced ELS?

Answer 19

internalizing symptoms (e.g. anxiety, avoidance), externalizing symptoms (e.g. aggression, hyperactivity), and social impairment

Question 20

ELS ____ the risk of psychiatric disorders

Answer 20

increases

Question 21

what were the results of the study on ELS on depression?

Answer 21

individual with short form SERT has high risk but ONLY when they experience child maltreatment

indicates that while genetic factors can make you more susceptible, it also has to do with their environmnent

Question 22

how did they study ELS on brain development?

Answer 22

study individual differences in how moms care for their pups and see if changes in maternal behaviours impact the expression of behaviour in the pups (related to mental dx)

individual diff: some moms spend less time grooming/licking

Question 23

what were the maternal effects on the HPA-axis?

Answer 23

GR are receptors for glucocorticosteroids (low affinity receptors that detect stress levels of cortisol)

in animals with low LG, have higher level of cortisol

increase in GR in the high-LG offspring in the hippocampus
–due to negative feedback system

Question 24

what was the conclusion of the study of epigenetic programming by maternal behavior?

Answer 24

low LG pups had more methylation and could be reversed if placed in the care of high LG moms

Question 25

what was the conclusion of the study on epigenetic regulation of GR in humans?

Answer 25

when suicide patients receive childhood abuse, show similar modifications to GR in human brain

els can have impact the particular genes (dna-methylation) that have long term effect on GR

Question 26

what were the 3 notable conclusions for adult neurogenesis?

Answer 26

1965: used H3-thymidine to label new born neurons in the dentate gyrus(DG)

1998: used bromodeoxyuridine (BrdU) to label new neurons in adult human DG

2013: examined C14 turnover in human hippocampal neurons to reveal adult neurogenesis

2018: used markers of progenitor cells to show undetectable neurogenesis in adult human DG

Question 27

what did they find in the study on active neurogenesis in adults (nuclear bomb)?

Answer 27

for people born before the event, if they live through the period, the radioactive content of the cells is higher than base since some cells form during the period of high C14

for people born after the rise, see the opposite: as they grow older, they have new neurons formed as the radioactive levels decrease

Question 28

what is the ongoing debate about adult neurogenesis?

Answer 28

maybe we dont need a lot of neurogenesis, but the process is still there (maybe its just so slow or minimal that its hard to detect)

Question 29

what is novelty suppressed feeding?

Answer 29

way to study anxiety in the mice

put bright lamp above container – they hate bright light so they avoid going to the center to get the food –> but theyre hungry so creates dillema

latency suggests how anxious the mouse is

Question 30

how did they use novelty suppressed feeding to study depression?

Answer 30

tx animals with diff antidepressants (including prozac)

found that shock tx does not reduce the latency of anxiety –> only chronic tx helps

suggests that long term antidep tx can reduce anxiety

Question 31

what were the results of the study on novel suppressed feeding?

Answer 31

X-ray treatment led to a reduction in cell proliferation in the SGZ, with no significant effect on the SVZ

apoptosis was selectively induced in the SGZ following X-ray treatment.

antidepressants reduced latency in sham but not hippocampal-irradiated mice

irradiation of brain regions rostral or caudal to the hippocampus did not prevent the effects of antidepressant treatment on latency in the NSF test

Question 32

what produced the same effects as antidepressants?

Answer 32

blocking neurogenesis

animals without knock out, increase in social interaction but in those knock out (more new born cells) have less social interaction and increased anxiety

Question 33

what is the impact of allopregnanolone?

Answer 33

potentiate gaba

gaba relates to brain inhibition –> help you sleep

Question 34

how does gaba relate to postpartum depression?

Answer 34

15% of women may suffer of post-partum depression after giving birth

shown in animals and humans that it has to do with the impact of steroids on gaba receptors

during preg, you have high levels of progesterone

problem: level of progesterone decreases drastically after birth –> so sudden drop in inhibition

Question 35

what is chronic social defeat stress in research methods?

Answer 35

natural stressor in rats is dominance/aggression in males

after mice experience the aggression, show depressive behaviour

house them together with a partition afterwards which is supposed to be highly stressful

Question 36

what is the social interaction test?

Answer 36

later on, some mice will try to avoid the white mouse

animals that were stressed will avoid the white mouse

some mice after being stressed will still go see the white mouse

Question 37

what pathways might be related to social stress in rats?

Answer 37

NAc in striatum and ventral hipp, mdt and pfc (these three send projections of NAc to control activity)

Question 38

what were the results of the study that looked at stress and the NAc?

Answer 38

compare nb of activated neurons in the regions that project to the nac

nb of active neurons decreases significantly in stressed animals in the vHIP

also studied activity of cells of these regions that project to nac
- in the vHIP, there are more activated cells in the stressed animals

implies that the vHIP to the NAc (bc of the increase in activity) make the naimal more susceptible to stress

Question 39

when the VHIP activity is _____, the mice interact more with the aggressive mouse

Answer 39

reduced

Question 40

how does TMS work?

Answer 40

works for regions close to the skull (ie cortex) –> stimulation to activate or suppress activity

Question 41

how can you induce neuroplasticity for treating mental disorders?

Answer 41

part of auditory activity has been related to auditory hallucination – try to use tms to reduce these

can do deep brain stimulation by implanting electrodes in the brain – useful for treating PD and dep/alzheimer’s