week 7 workshop Flashcards
What happened to Ben?
- Angry
- He had Brain tumour
-when tumor removed he was happy
What happened to the aggressive 13 year old?
-Brain tumor removed
-became calm and was able to get along with his classmates
What happened to the clock tower terroist?
- reasonable man turned very aggressive
-mass murder
-they found aggressive cancer in his brain it was pressing on hithalamus hypothalamus and amygdala
How can a tumor cause uncontrolled anger and agression?
- we need to understand the limbic system
What is the limibc lobe?
- coined by Paul Broca
- confirmed by James Papez
What is Papez’s Loop?
earlery stages of thinking about limbic system
What is the limbic system?
group of interconnected regions of the brain
- responsible for emotions, responses, are associated with survival, reproduction and memory
= It receives direct input from the olfactory system
limbic system has a strong modulatory influence on the autonomic nervous system
what is the fight or flight response?
- autonomic servous system [ANS] if repsonsible for:
-regulation of the bodys metabolism
-adjusting bodys eneergy rewquirment according to need.
Can be strongly influenced by consious awareness even if it is something we perceive unconsioculy
2 components of ANS
Sympathetic NS - fight or flight
Parasympathetic NS - rest and digest
what are the main components of the limbic system?
Cingulate gyrus
Amygdala
Cerebral cortex [frontal olfactory]
hippocampal formation
septal area
hypothalamus [mainly mammillary nuclei]
thalamus [anterior and dorsomedial nucleus]
what is the septal area?
connnected to ventral tegmental area [addictive behaviours]
stimluation in this area:
-pleasure, lust, euphoria, orgasm
erection
rats can perform 6000 bar presses an hour to obtain self-stimluaion of this region from imolalnted electrodes. Disinterested in drinking water became severly dehydrated.
what is the amygdala?
connected to the olfacotory center
evaluating threats
changing our behaviour according to a FFF status
much of this evaluation is done unconsciously
connected to hippocampus and hypothalamus.
when amaygdala is removed it causes flat/lack fear/lack empathy/socially withdrawn
amydala ia implicated in anxiety and phobias
Essentials of genetics
essential principles of genetics:
-every cell in our bodies contain same 23 pairs of chromosomes
females have 2 copies of the X chromosome while males have one X and one Y
one set comes from either parent
chromosomes are made of DNA
GENES ARE SEGMENTS OF DNA THAT CODE FOR THE SYNTHESIS OF A SPECIFIC PROTEIN
MATHCING GENES FROM OUR TWO PARENTS ARE CALLED alleles.
given gene may have differnt variants [alleles] in the population but only two alls are present in an individual person
alleles can simetimes resultt in different phenotypes [observable traits]. with cerrtain allleles being dominant [overiding the traits of the other allele]
recessive genes x chromosome preferentially affect males because they lack a second allele [x linked]
what is the warrior gene?
gene called MAOA. - linked to anti social behaviours, violence, identified in 1993 in large Dutch family notorious for violence from the males.
Low functionign MAOA allele, is x linked and increases aggression by making carriers over reactive to frustration or threat.
stonger reaction in limbic system being activated - when threatened.
However there are still many steps between a gene creating a protien and exective function and behavioural outcomes
Alcohol
Humans have been drinking alcohol for a while
we have specialised enyzymes to breakdown ethanol
however it may have been a means of sanitisation
case study Mike M
-heavy drinker in teens
-heavy weight
-30 yrs later dependance on alcohol
-suffered severe short term memory loss
Chronic alcoholism
he has something called Korsakoffs Syndrome
how does alcoho, affect brain function?
- ethanol is a small lipid-soluble molecule that readily gets into the brain and the blood supply
Ethanol binds to many of the major neurotransmitter receptor types, changing their activity
primary effects are on signal pathways that use GABA[inhibitor]
How does it affect GABA?
inhibitor
reduces activation of neurons
ethanol binds to GABA receptors on the postsynaptic membrane, which increases the sensitivity of the reception r
this makes cells less likely to have a response
70% of all neurons have GABA receptors so the effect of ethanol is widespread
How will this effect behaviour?
midl depression of neirol activity in the limbic system
has an axiolytic effect
makes someone more relaxed.
high doses of ethanol depresses ativity in motot cortex and the cerebellum.
impaired coordination of the limbs, speech, eye moevments, sever intoxication can lead to flaccid paralyssi and even cessation of breathing
effects sensory cortex
numbs awareness of pain
leads to risk taking
ethanol also acts on dopaminergic cells in the septal area, increased release of dopamine
what are the genetics of alcoholism?
Type 1 alcoholics: develope problems gradually after age 25 and are less likely to have relatives with the disease
type 2 alcoholics: rapid onset before age 25, most are men they frequently have close relatives with alcoholism
mothers who drink in pregnany increase likelihood of child having alcoholism.
Sons of alcoholics find alcohol more relaxing than others. need more drinks
heavy weights
such sons have 60% likelihood of becoing an alcoholics in later life.
can we link genes to alcoholism?
genes coding for certain proteins have been linked to alcoholism.
Dopamine type 4 receptor: alcoholics frequently have a less sensitive form of this receptor [is not easilyy activated by dopamine], causing them to seek greater levels of drunkness to get pleasure reward
COMT enzyme: degrades dopmine in the synpatic cleft.
alcoholics have more active form of this enzyme. clears dopamine wuicker and blunts the effect of dopamine release.
both genes mean that these people will seek more alcohol than others to get the pleasure response.
how does alcohol cause memory loss?
more pronounced for transfer from short to long-term memory
brief short-term memories and long-term memories form before intoxication remain intact
school
acts to suppress NMDA receptors in the hippocampus
hippocampus volume reduction correlates later in life with memory loss
Wernicke-Korsakoff Syndrome
alcohol caused vit B1 deficiency. which is needed to metabolise glucose to produce energy in the brain/
Wernicke encephalopathy:
-confusion-loss of mental activity that can become coma or death
-loss of motor coordination
-back-of-forth movements of eyes
brain shrinkage
Korsakoffs psychosis:
- inability to form new memories
-loss of recent memories
-making up stories
-seeing or hearing things that aren’t there.
causes neurons to shrink and become healthy
anterograde amnesia
