Behaviour + neuroscience Flashcards
(159 cards)
1
Q
Neuroscience definition
A
- Not just the brain!
- Study of the STRUCTURE + FUNCTION of the NERVOUS SYSTEM!!
- NERVOUS SYSTEM:
1. Brain
2. Neurone
3. Synapses
2
Q
Behaviour definition
A
- observable actions of humans + animals.
3
Q
Behaviourism definition
A
- HISTORICALLY using behaviour as an indicator of internal mental processes
INTERNAL MENTAL PROCESSES
= eg. What is going through your mind when ordering coffee?
= thinking, remembering, problem-solving, emotions, perceptions
4
Q
Why does behaviourism not work alone? 2
A
WE CAN’T OBSERVE INTERNAL PROCESSES OF THE MIND JUST BY BEHAVIOUR ALONE!!
- SAME observable behaviour could have DIFFERENT internal processes
- Eg. Alex and Sam are both staring silently at a math problem
- Alex feels nervous, Sam is recalling a formula - Some behaviours can MASK certain internal processes
- Eg. A smile could represent happiness or someone masking sadness
5
Q
Behavioural neuroscience
A
- BRAIN —> BEHAVIOUR + MIND (internal processes)
- How the brain CONTROLS the behaviour + mind!!
- Involves research on ANIMALS (since they mirror human behaviour)
6
Q
What limits our understanding of the brain? 4
A
- RELIGIOUS/MORAL VIEWS
- Not allowed to dissect corpses - METHODOLOGICAL LIMITATIONS
- Ie. Our current tools are not advanced enough to capture the complexities of the brain - SERENDIPITY
- Reliance on discovering things by chance - SCIENTIFIC CONSERVATISM
- When people in the field still believe something is true despite the fact that it is disproved
- People take time to take up this new view
7
Q
Behavioural neuroscience // Behavioural Physiology // physiological psychology // biological psychology
- IDENTIFY KEY WORDS = behavioural, physiology, biological
A
ALL THE SAME THING - studying BRAIN —> BEHAVIOUR + MIND (internal processes)
KEY TERMS MEAN MORE SPECIFIC
- Behavioural = animal research
- Physiology = human research
- Biological = more in depth, expert level
8
Q
Neuropsychology(2 focuses)
A
Links BRAIN DAMAGE (LESIONS) with psychological processes
- CLINICAL
- Before surgery: assess risk - eg. would brain surgery impact…
- After surgery: assess impairments + improvements - RESEARCH
9
Q
Psychopharmacology
A
NEUROCHEMISTRY in mind and behaviour
- Natural = neurotransmitters, hormones
- Artificial = drugs
10
Q
Comparative neuroanatomy + psychology2
A
STUDYING DIFFERENCES + SIMILARITIES IN SPECIES TO EXMAINE….
- Brain EVOLUTION
- Origin and purpose of behaviours
11
Q
Cognitive neuroscience
A
- Connects BRAIN with COGNITION (ie. memory, language, perception, decision making)
- Connects BRAIN REGIONS with FUNCTION
12
Q
Cognitive neuroscience - what tool is commonly used?
A
- FUNCTIONAL brain imaging(fMRI)
13
Q
Psychophysiology
A
- Now included in COGNITIVE NEUROSCIENCE
- Longer history, includes more BASIC RESPONSES like “startle”
14
Q
Psychophysiology - what tool is commonly used?
A
- EEG
15
Q
Neuromorphic computing
A
- Using electronic CIRCUITS to MIRROR neural STRUCTURES in the brain
16
Q
Cognitive computational neuroscience
A
- AIM to characterize NEURAL COMPUTATIONS that underlie COMPLEX BEHAVIOUR
17
Q
Silico neuroscience
A
- Use of computer modeling / simulations
- BROAD TERM
18
Q
OUR CURRENT UNDERSTANDING
A
BRAIN → MIND (internal processes) + BEHAVIOUR
** Brain CONTROLS mind + behaviour
19
Q
ANCIENT EGYPTIAN CULTURES 2
A
- Thought that the HEART controlled → MIND + BEHAVIOUR
- Due to constant beating of the heart during times of fear + happiness
- BUT linked brain damage + mental symptoms
20
Q
HIPPOCRATES 2
A
Hypocrite - had barely the right tools // but first one to bring close to our CURRENT UNDERSTANDING
- Established BRAIN → BEHAVIOUR
- Limited tools
- Dissection of corpses not allowed in Greece, only observed through open wounds
- Came to conclusion by noticing brain damages affects behaviour
21
Q
RENE DESCARTES
A
Renee - most important life lesson = “the man follows where the mind goes” // sometimes forget though
- Established connection between MIND + BEHAVIOUR
- “I think therefore I am” - Believed involuntary reflexes + behaviour driven by a system of FLUID + PISTONS
22
Q
GALVANI
A
Dolce + Gabbana - brands are “correct” - formed correct ideas on nerve cells-
- Suggested nerve signals are ELECTRICAL (not fluid)
- Rejected the idea of animal spirits flowing through hollow nerves
- SERENDIPITY = Chance discovery by noticing that applying electrical charge on a frog’s level = muscle contraction - Suggested nerves must be coated in fat to prevent electricity from leaking out
23
Q
GALL
A
Ball - playing ball requires 3 traits: personality with brain + organisation of team + personality with looks
- MODULAR ORGANISATION of the brain
- Each part of the brain (“organs”) do different things - Physiognomy
- Believed personality has to do with facial features/appearance
- Eg. all criminals will look similar - Phrenology
- Brain + personality relationship
- Believed bumps of the skull / “skull map” would determine personality traits
24
Q
BROCA
A
- Provided EVIDENCE of brain modularity
- Patient = Leborgne
-> Damage to SPECIFIC section of the brain (LEFT FRONTAL LOBE )
-> SYMPTOMS = LIKE A BABY!!
-> Unable to speak BUT normal chewing + language comprehension
-> NO brain scans at the time, only unusual deficits found through autopsy - called locationslists
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Broca area - function
Language production
26
WERNICKE
- Provided EVIDENCE of brain modularity
-> Damage to SPECIFIC section of the brain (posterior part of the SUPERIOR GYRUS)
-> LIKE A BABY THAT WAS JUST BORN
-> Unable to understand speech BUT normal hearing + language production
27
BRAIN - WHAT IS ITS WEIGHT? RELATIVE TO BODY?
- 1400 grams
- 3% of body weight
28
Brain - how many neurons + synapses + circuits?
- NEURONS = 100 billion
- SYNAPSES = 1,000,000 billion
- CIRCUITS = 10 to the power of 1 million
29
Brain - how much energy does it consume? Is it energy efficient?
- Consumes 20% of the body’s energy resources
- Energy efficient - runs on 20 Watts (simple light globe)
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Brain - information processing similar to?
- VERY similar to COMPUTER SYSTEM PROCESSING
31
Are humans special compared to other animals?
- NO!!
- Animal brains have SIMILAR STRUCTURES + NEUROTRANSMITTERS to humans
- Animals show similar BEHAVIOUR to us too
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What makes an animal more intelligent?
- THE MORE NEURONS → more synaptic connections between neurons → more COMPLEX FUNCTION can be done → more intelligent
33
What DOES NOT make an animal more intelligent?
SIZE of the brain
1. Eg. a dog is more intelligent than a big giraffe
2. Even after considering relative size (ie. consider the animal’s body size), still not an indicator
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Can one area of the brain be larger than other areas?
YES!!!!
- Each animal will have different sizes for each area
- The bigger the brain area → more dedicated to that particular FUNCTION / more specialised in that skill
35
Charles Darwin + behaviour across species - what was his conclusion?
WHAT HE BELIEVED:
- All human behaviour derives from natural processes received from ANCESTRAL SPECIES
- Rather than Gods or angels
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Charles Darwin + behaviour across species - debate? 2
1. Religious debates
- God gave morals to us, not old animals!
2. Moral debates
- Why should I be responsible for my greed/uncontrollable feelings if it’s from old animals?
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Comparative psychology - when does it get difficult?
- It is easy to compare brain structures
- But comparing CONSCIOUS/SUBJECTIVE experiences is much harder
-> Conscious = when you are AWARE what is happening around you/what you are feeling
-> Subjective = what you FEEL about what you are aware of
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Comparative psychology - do animals have the same brain PROCESSING as us? What evidence?
YES!!!
- This is proven through similar responses to VISUAL ILLUSIONS
- Eg. Kinetic depth effect = illusion where moving 2D shapes makes you THINK you are seeing 3D
39
Animals as models for human behaviour - why are MOUSE good for experiments?
1. ADAPT to a variety of environments
2. Only 8 WEEKS to develop fully
3. Produce LARGE NUMBER OF OFFSPRING
- This also makes experiments cheaper, most cost-efficient
4. Offspring are SUPER SMALL
- Can be placed in tubs easily
- Lots can be stored at one time
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Allen Brain institute
- Creates DETAILED MAPS
- Allows us to see brain areas, neurons, genes!
- Done by using data from mice + human brain
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Human brain project
- Designing COMPUTER CHIPS to SIMULATE the human brain’s neurons + synapses
- Falls under “NEUROMORPHIC COMPUTING” (brain inspired computing)
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Human brain project - why simulate the brain?
1. Reduce the need for animal experiments
2. Improve the validation of data + experiments w/ computational validation
3. Study diseases in silico experiments
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DIVISIONS OF THE NERVOUS SYSTEM
- Whole nervous system → PNS (peripheral) + CNS (central)
- PNS → somatic + autonomic
- Autonomic → enteric, parasympathetic, sympathetic
44
CNS - what does it consist of? 3
1. Brain
2. Spinal cord
3. Retinal cells within the eyeball
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Spinal cord - what is it surrounded by?
- Cord = One straight line extending from the brain
- CUSHIONING IT on either side of the line are VERTEBRAE
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VERTEBRAE - function
1. Protection of the spinal cord
2. Flexibility for the body when moving
47
PNS - GENERALLY what types of nerves what does it consist of 2
1. Cranial nerves = nerves that connect to the brain
2. Spinal nerves = nerves that connect to the spinal cord. Tend to run along the VERTEBRAE
48
PNS what does it consist of? 2 subdivisions
1. Somatic nervous system
- Involves SKELETAL MUSCLE
- VOLUNTARY contractions
2. Autonomic nervous system
- Involves smooth muscle, cardiac muscle, glands
- INVOLUNTARY contractions (Eg. can’t think “make my heart beat faster”)
49
Somatic nervous system - 2 general functions
1. Nerves INTO the CNS
- CNS RECEIVES signals (eg. body position, temp).
- Comes from SENSORY ORGANS
2. Nerves OUT from the CNS
- Brain SENDS signals
- Goes to SKELETAL MUSCLES, causes CONTRACTION
50
Peripheral sensory areas:
- LOCATION where SENSORY RECEPTORS are found.
- EG. skin, eyes, or ears
51
Sense modalities:
- Types of STIMULI detected by receptors.
- Eg. light, sound, or pressure
52
Somatic nervous system - 3 types of nerves
1. EFFERENT, CRANIAL nerves → sends signals AWAY from the brain. Brain → contraction of muscle
2. AFFERENT, CRANIAL nerves → sends signals INTO the brain. Stimulus detected by receptor → Brain
3. Spinal nerves → sensory + motor pathways
53
Autonomic nervous system - 3 subdivisions
1. Parasympathetic
2. Sympathetic
3. Enteric
54
Parasympathetic + Sympathetic? Relationship?
- OPPOSITE to each other
- Both impact important bodily functions + responses
55
Parasympathetic vs Sympathetic - function?
Parasympathetic = REST + DIGEST
- Prepares body to REBUILD energy stores
Sympathetic = FIGHT OR FLIGHT
- Prepares body for ACTIVITY (ie. to use energy)
- Times for stress or excitement
56
Parasympathetic vs Sympathetic - examples to compare?
PARASYMPATHETIC
- Eg. slow heartbeat
- Eg. increases digestion + urinary output
SYMPATHETIC
- Eg. increases heartbeat
- Eg. slows down digestion + relaxes the bladder
57
Parasympathetic + Sympathetic - what are they driven by?
PARASYMPATHETIC
- Ach (acetylcholine)
SYMPATHETIC
- NA (Noradenaline)
- Adrenaline
58
Enteric nervous system (ENS) - is it smart?
- Contains 100 million neurons
- The “2nd brain”
- Nearly every neurotransmitter found in the brain also found in the gut
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Enteric nervous system (ENS) - what is it consisting of?
* The GUT
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Enteric nervous system (ENS) - function?
- BASIC = digestion
- ANOTHER MAJOR ROLE = emotions + stress
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Enteric nervous system (ENS) - can it act on its own?
- IT CAN ACT AUTONOMOUSLY, WITHOUT THE BRAIN!!!
- Has its own reflexes and senses
- Only part of the PNS that can do this!
62
Enteric nervous system (ENS) - connection with the brain?
- So intelligent that…90% of connections/messages go FROM the gut TO THE BRAIN!!!
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Anterior
Posterior
Superior
Inferior
Anterior = front
Posterior = back
Superior = top
Inferior = bottom
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Neural axes
imaginary line drawn FROM the spinal cord TO the FRONT of the brain
- human neural axis BENDS (not a straight lie) because head is perpendicular to the back
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Lateral
Medial
Lateral = away from the midline
Medial = towards the midline
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Ipsilateral
Contralateral
Ipsilateral = on the SAME SIDE of the midline
Contralateral = on the OPPOSITE SIDE of the midline
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Callosotomy
PROCECURE of cutting the corpus collosum
- done to stop epileptic seizures
- by stopping communication between hemispheres
68
what is the largest structure of the human brain?
cerebral cortex
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parkinson's disease - if symptoms are weakness, tremors, limb rigidity, ppor balance, difficulty initating movements - damage to what part of the brain?
these are highly automated, but not necessarily automatic
- hence this is due to dysfunctional BASAL GANGLIA
70
where is the midbrain and hindbrain located?
brainstem
71
Human frontal cortex - is it different from other animals? 2
1) relatively larger than non primates
2) a higher level of connectivity with rest of the brain
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What happens if the frontal lobe is damaged? 3
1) personality changed MASSIVELY
2) unable to plan
3) cannot make decisions
73
What is the effect of a neurotransmitter binding to a receptor? general, 2 types
2 TYPES OF NEUROTRANSMITTERS
1) Excitatory
2) Inhibitory
AFTER NEUROTRANSMITTER BINDS TO RECEPTOR...
- there will be electrical changes in the postsynaptic nerve cell
- as binding can result in CLOSING/OPENING of ion channels
SPECIFICALLY....2 POSSIBLE CHANGES ON ELECTRICAL:
1) Excitatory postsynaptic potentials (EPSPs) - depolarisation -> closer to threshold
2) Inhibitory postsynaptic
potentials (IPSPs) - repolarisation - further from threshold
TOGETHER...
- The combined effect of
EPSPs and IPSPs is called
NEURAL INTEGRATION
- If TOTAL reach threshold potential (-50mV), then action potential WILL BE GENERATED
- The neuron will only fire if the sum of the excitatory inputs is sufficiently
greater than the inhibitory inputs to cause the membrane potential to
pass the threshold of activation.
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NEURAL INTEGRATION
- The combined effect of
EPSPs and IPSPs is called
NEURAL INTEGRATION
- If TOTAL reach threshold potential (-50mV), then action potential WILL BE GENERATED
- SO...The neuron will only fire if the sum of the excitatory inputs is sufficiently
greater than the inhibitory inputs to cause the membrane potential to
pass the threshold of activation.
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Excitatory postsynaptic potentials (EPSPs) - caused by what neurotransmitter?
Glutamate
- EXCITATORY neurotransmitter
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Excitatory postsynaptic potentials (EPSPs) - what change is seen in the neuron?
- EPSP's DEPOLARISE (make positive) the
postsynaptic cell
membrane
- becomes closer to the THRESHOLD OF ACTIVATION
-SO... increases the LIKELIHOOD that an action
potential will be triggered in
the postsynaptic neuron
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Inhibitory postsynaptic
potentials (IPSPs)
- REPOLARISE/HYPERPOLARISE (more negative) the
postsynaptic cell membrane
- becomes further to the THRESHOLD OF ACTIVATION
- SO...decreases the LIKELIHOOD that an action
potential will be triggered
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Inhibitory postsynaptic
potentials (IPSPs) - caused by what neurotransmitter?
(GABA)
- INHIBITORY neurotransmitter
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What are neuromodulators? 4 examples (no need to rlly memorise)
1) Dopamine
2) Noradrenaline
3) Serotonin
4) Histamine
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Neuromodulators vs neurotransmitters
- FAR FEWER NEURONS relaying neuromodulators compared to neurotransmitters
eg. - only a few neurons will release serotonin (vs the whole brain)
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What does it mean if a receptor is specific? 2
1) WHAT BINDS
= Each receptor can generally only be activated by one
neurotransmitter
2) THE THING BINDING IS DONE TO
= Each receptor has a very specific function
-> eg. when a neurotransmitter binds to the receptor this will
trigger the same event every time
82
How do drugs work?
- MIMIC the shape of neurotransmitters/neuromodulators
- so that it can FIT into the SPECIFIC shape of the receptor
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Agonist
TYPE OF DRUG
- Has the same EXACT SHAPE as a neurotransmitter/neuromodulator
- Hence will ACTIVATE the receptor like normal
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ANTAGONIST
- DOES NOT have the same EXACT SHAPE as a neurotransmitter/neuromodulator
- So will just SIT on the receptor and BLOCK IT
- Hence natural compound can't activate the receptor
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Do drugs have a large impact?
YES
- Drugs can impact every stage of neurotransmitter function
(synthesis of neurotransmitters, release of neurotransmitters, neurotransmitters + receptor binding)
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AGONISTIC DRUG EFFECT 2
1) increase synthesis of neurotransmitters
2) increase release of neurotransmitters
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ANTAGONISTIC DRUG EFFECT
1) blocks synthesis of neurotransmitters
2) blocks release of neurotransmitters
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Brain imaging
- Assess brain STRUCTURE
- Done non-invasively - ie. without dissection/damage to the brain
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Lesions
Brain damage
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Neuropsychological methods
- Uses patients with brain damage to determine functions of the brain
- Eg. damaged hippocampus → infer its role in memory
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Neuropsychological methods - cons 2
1) Can't be certain
- eg. can't be sure hippocampus = memory, as other brain regions to be considered
- As can't control lesion size/location in patients
2) Replication issue
- Each patient experiences brain damage in unique areas, all different
- So can’t find identical patients → can’t replicate
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Experiments of nature
- when Experimenters rely on naturally occurring brain injuries
- Not lab controlled
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Methods for understanding the brain. -SUMMARISED
EEG
- Cap covered w/ electrodes
- Per electrode = electrical activity of millions of neurons
Electrophysiology
- Microelectrodes
- Electrical activity in one/small network of neurons
MRI (general)
- Magnetic coil
- Brain structure (imaging)
MRI (eg. DTI)
- Magnetic coil
- White matter
MRI (eg. fMRI)
- Magnetic coil
- Activity of different areas of the brain → blood oxygen levels
PET
- Individual chemicals (eg. neurotransmitters)
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EEG - electroencephalography + electroencephalogram
-Electroencephalography = equipment/method used
- Electroencephalogram = data received
- EEG refers to BOTH of these combined
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EEG - what is it, what does it measure
- Blue cap worn with electrodes all over it
- EACH electrode detects millions of neurons + measures the neuron’s change in electrical activity
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EEG - data
- Electrical activity are electrical signals sent to the machine
- These signals are shown with spikes//peaks - height represents magnitude of electrical activity
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EEG - uses
- Diagnoses epilepsy
- During seizures, electrical activity would be much higher
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EEG - pros 4
1) Good temporal resolution
- Very accurate in measuring time
- Eg. Measures electrical activity changes within milliseconds
2) Cheap
3) Portable
- As it’s a cap, electrical activity can still be recorded when the patient is moving around
- Also good for patients who can wear it while going back home
4) Safe, no real risk
99
EEG cons 2
1) Poor spatial resolution
- Can’t determine exactly which area of the brain the signal has come from
- Eg. signal over here broadly, but can’t say specifically where it is
2) Only detects activity on the surface of the cortex
- Ie. can’t detect activity in central regions of the brain
100
Electrophysiology - how it started, what is is now
- Recorded action potentials (electrical signals) in ONE neuron
- Possible by using the giant axon of an Atlantic squid
- Led to microelectrodes / multi-unit recording electrodes
- Used to detect singular/smaller groups of neurons
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Electrophysiology - pros
Since detecting electrical activity in an INDIVIDUAL neuron, good if you want to know what the neuron is DOING
102
Electrophysiology - cons
1) Highly invasive
- High risk of infection
- Requires chopping up part of the skull
2) Can record individual neurons or small network, but nothing more than this
103
What is MRI
- A coil which generates a very strong magnetic field
- Much stronger magnetic field than earth
- Allows us to see brain structure (imaging)
104
How does MRI work?
Magnetic field
- Magnetic field passes through person’s head
- Hydrogen atoms in the blood aligns with this magnetic field
Radio
- Radio frequency waves disrupt this alignment.
- This produces a signal
- BUT each area of the brain contains different levels of h2o
- So…diff areas of brain tissue emit different signals.
Picture
- These signals are converted into images of the brain by software
- Hence allows us to observe brain structure
105
DTI - diffusion tensor imaging
- Same as MRI equipment
- But analysis is on something different
- Detects large axon pathways (white matter) which flow through the brain + connect different regions of cortex
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fMRI - functional imaging - what does it do, how does it do this?
WHAT?
- Determines function of different parts of the brain by its ACTIVITY
HOW?
- When the brain area is used, energy is needed
- Oxygen is used up from the blood
- Oxygenated blood = doesn’t distort the magnetic field → blood vessels less visible
- Deoxygenated blood = distorts the magnetic field → blood vessels more visible
-From here, use BOLD signals, which tracks the ratio of oxygenated vs deoxygenated blood
- So we can say it correlates brain activity w/ behaviour
107
fMRI - functional imaging - why might there be a delay in results
Let’s say we want to show hippocampus is active memorising something
- SO... when hippocampus is active, blood oxygen decreases
- But it will TAKE TIME for it to take in oxygen, get signals etc.
108
MRI pros 2
1) High spatial resolution
- Can identify EXACT region of the brain where function is occurring
2) Many uses (3)
- Allows us to see the structure (anatomical) + functions of different brain regions
109
MRI cons 4
1) MRI machines are expensive
2) Large equipment
- need specialist facilities with multiple rooms, machine has to be kept in a magnetically shielded room
3) Unsafe if there is other metal in the MRI room (get sucked into the MRI magnet)
4) Requires specialist staff with radiography training
110
PET - what is it
- Uses TRACERS
- Radioactive substances
- These bind to CHEMICALS (eg. glucose, neurotransmitters)
SO...
- Allows you to see glucose metabolism (energy consumption)
- Allows you to see neurotransmitters floating in the brain, what receptors they are binding to
- Allows you to detect neurotransmitter levels/amount
111
PET - importance?
buildup of certain chemicals / metabolism of certain chemicals can point towards and therefore diagnose certain diseases!
112
PET - pros 1
Detect chemicals in the brain specifically
113
PET - cons 4
1) Expensive
2) Requires specialist staff + facilities
3) Low spatial resolution compared to MRI
- Eg. for energy consumption better to use MRI (o2 levels) which is a specific area rather than PET which is just glucose molecules
4) Radioactive tracers
- have to be injected into the patient’s blood
- Although safe, there is a slight risk
114
Brain modification/modulation - 3 examples
1) Brain regions are removed/destroyed
2) Drugs
3) Electrical stimulation of brain regions
115
Brain modification/modulation - 3 examples - specifics
1) Brain regions are removed/destroyed
-> Permanent = frontal leucotomy = eyelid
-> Temporary = TMS = magnetic impulse, virtual lesion
2) Drugs
- Neural connections
3) Electrical stimulation of brain regions
-> ECT = seizure = depression
-> tCDS = 2 sponges = performance
116
Uses of brain modification/modulation? 2
1) Medical treatment
- Removal of abnormal brain tissue which causes abnormal brain function
- Drugs which target abnormal function of neurotransmitter systems
2) Enhancement
- To improve health so that it is above or better than normal
117
Brain modulation - how do these practices benefit research?
- By removing entire areas, we can know whether a brain region is necessary for a certain task (ie. CAUSATION)
- MRI only provides CORRELATION, we can’t be certain
118
Ablation studies?
Ablation = carry away
SO…
- This means deliberate lesions (ie. intentional removing, destroying of brain tissue)
- This allows for higher degree of precision (we know exactly that region is responsible, no other regions involved)
119
Ablation studies - done on who?
- Humans = strictly medical treatment
- Animals = for research purposes
120
Moniz - what did he believe + what did he create through this belief
- He believed changing synaptic structures could change human behaviour and cure mental illness
PREFRONTAL LEUCOTOMY
- Cut off nerve connections between the frontal lobe (esp prefrontal cortex) and the rest of the brain
- Initial belief right, but where he took this was wrong
121
Prefrontal leucotomy - how is it done 2
1) Skull
- Drill holes in the skull
- Insert a tool called a leucotome into these holes
- Wire released from the leucotome
- Rotated to cut a small piece of the frontal lobe
Eyes
- Insert a sharp tool above the eyelid
- Move it side to side
- Cut connections between frontal lobe and the rest of the brain
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Prefrontal leucotomy - how did this idea come about?
- Linked personality to frontal lobes
- Removal of frontal lobes of chimpanzees
- Made them calmer + more cooperative
-Hence believed it could cure psychiatric disorders etc.
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Prefrontal leucotomy - was it successful?
- Initially seemed successful
- Calmed patients down
BUT
- Slowly shown to be ineffective
- Caused major changes in personality
- Eg. apathy, inability to plan, emotional unresponsiveness, disinhibition (ie. impulsive behavior)
124
Electrical brain stimulation - for research?
- Electrical stimulation of the frontal cortex. Done in dogs
- Triggered contractions of muscles on the opposite side of the body
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Non-invasive electrical stimulation - 2 types
1) ECT
2) tCDS
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ECT - what is it?
Electroconvulsive therapy
- Electrical stimulation of the frontal lobes
- Made to be strong enough to cause a seizure
- Seizures reduce psychiatric symptoms (esp severe depression)
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tCDS - what is it?
Transcranial direct current stimulation
- Connect a battery onto 2 sponges
- Attaches these 2 sponges onto the head
- Sends a low electrical impulse to the brain
- Meant to improve cognition, attention, memory, performance
- But only improvement by 5%
128
TMS
Transcranial magnetic stimulation
- Stronger than MRI
- Coil carries an electrical current.
- This generates a magnetic pulse which increases/decreases activity of the cerebral cortex
- Virtual, temporary lesion - disrupts tissue
- Used to treat depression and OCD
129
TMS - cons
- Painless unless it causes muscle contraction
- Eg. can cause arms to fly out
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Drugs + brain modulation
- impact neurotransmitter function, therefore neural connections
131
Rate law
- Strength of stimulus determined by frequency, NOT magnitude
- Stronger stimulus = makes neuron fire/generate action potential more frequently
- Stronger stimulus DOES NOT MEAN action potential will be “bigger”
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Synaptic connection / synapse
- Link between 2 neurons
- Includes presynaptic neuron, synaptic cleft, postsynaptic neuron
133
Activation of synapse + firing of postsynaptic neuron
Activation of synapse
- Action potential reaches end of the presynaptic neuron AND signal sent from one neuron to another across the synapse
Firing of postsynaptic neuron
- Generation of action potential
134
Brain plasticity
- The brain is not fixed
- It is like clay - it CHANGES
- It changes its structure and function based on what you do, perform, think
135
Brain plasticity - 2 examples
1) SYNAPTIC PLASTICITY
- Strengthening of synaptic connections
- Weakening/removal of synapses
- Generating new synaptic connections
2) NEUROGENESIS
136
Strengthening/weakening of synaptic connection - name of process?
STRENGTHENING =
Long term potentiation (LTP)
WEAKENING = Long term depression (LTD)
137
Do the LTP and LDP work tgth?
YES!!
- LTP and LDP are important together
- Helps the brain adapt to current needs
138
How can synaptic/neural connections be strengthened?
- If you do a skill a lot
- Activation of the synapse will be REPEATEDLY ACCOMPANIED by firing of postsynaptic neuron (ie. simultaneously or at the same time)
- Makes the synaptic connections stronger
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Stronger synaptic connection? - what does it mean
- Postsynaptic neuron becomes MORE SENSITIVE to neurotransmitter release (by the presynaptic neuron)
- Easier for signals to pass through
- Postsynaptic neuron more likely to reach the THRESHOLD OF ACTIVATION
- Action potential will be generated more FREQUENTLY
- NOT the idea that action potential will have larger magnitude (corresponds to the rate law!)
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How can synaptic/neural connections be weakened - examples?
Called “USE IT OR LOSE IT”
- Skills not done enough
- Neural networks not stimulated efficiently
- Fading of memories + loss of skills
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Weaker synaptic connection? - what does it mean
- Postsynaptic neuron becomes LESS SENSITIVE to neurotransmitter release (by the presynaptic neuron)
- Postsynaptic neuron less likely to reach the THRESHOLD OF ACTIVATION
- Action potential will be generated less FREQUENTLY
- NOT the idea that action potential will have smaller magnitude (corresponds to the rate law!)
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“Neurons that fire together wire together”
Repeated activation and firing of neurons = stronger synaptic connection
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Synaptic plasticity - importance 3
1) Used for learning + memory
2) Used for motor skills, practiced movements
3) Allows for you to adapt
Eg. As a kid you learn how to crawl. Need to weaken synapse or else we will still be crawling!
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Is the brain always active?
- Yes, even during sleep
- Allows you to CONSTANTLY maintain/strengthen/remove/weaken synaptic connections
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Past+future activation - do they impact?
PAST activation of neurons WILL impact FUTURE activation of neurons
Eg. constant activation + firing strengthens synaptic connections → makes future firing much more frequent
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Neurogenesis
- New neurons can be generated
- Used to replace dead neurons
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Neurogenesis - does it happen across the whole brain?
- NO!!
- Restricted, only occurs in the Hippocampus + Olfactory bulb
- In other areas, neurons are not replaced, will forever be destroyed
- Hence why severe brain damage can’t be reversed
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Brain Rehabilitation
- After brain damage…
- Rehabilitation - repeated practice is done (eg. walking)
- Brain area responsible for movement is damaged - it cannot be restored :(
- BUT other brain areas can learn movement instead - by constantly using the same skills, LTP + LTD allows for the formation + strengthening of new synaptic connections
- SO…healthy brain regions take over damaged brain regions
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Motor control - example
HITTING A BALL IN TENNIS
- Goal = hit the tennis ball nicely
- Sensory signals/info = tennis ball, opponent, kids playing
- The brain filters + selects sensory cues needed for the goal
- Important sensory cues maintained in the FRONTAL CORTEX + working memory
- Brain sends out signals to muscles for contraction + coordinates balance
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Motor control 3
Ability of the brain to…
1) Take in sensory signals/information
2) Quickly process this information, see what is important for the goal
3) Coordinate movement to reach this goal
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Motor control - takeaway
- Lots of areas of the brain
- All highly integrated/connected via synapse connections
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What are the 3 components of emotion?
1) Behavioural
- OBSERVABLE actions or expressions
- Eg. smiling, crying, posture
- Eg. dog growling, aggressive posture like teeth, tail up
2) Autonomic
- Automatic body changes, physiological
- Fight/flight or Rest/digest
- Sweating, increased heart rate
3) Hormonal
- Supports autonomic change
- Eg. adrenaline further increases blood flow to the muscles + respiration for flight/fight
ACCOMPANIED BY… conscious awareness of these changes = “feelings” - eg. heart beating + smiling = feeling happy
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Why are feelings important? 2
1) Motivators
2) Expresses an animal’s intentions
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Where have emotions come from?
Evolution, Charles Darwin
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What triggers the 2 parts of the autonomic system?
1) Sympathetic branch → triggers fight/flight response
2) Parasympathetic branch → triggers rest/digest response
Eg. dog defending, Sympathetic branch activity increases, Parasympathetic branch activity decreases
Eg. heart rate increases, blood from digestive system sent to the muscles
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3 components of emotion - same part of the nervous system?
- Each component controlled by diff parts of the nervous system
- the AMYGDALA coordinates + INTEGRATES all these diff parts
- Sends signals to the autonomic + hormonal responses
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Emotional responses pros
- Survival in life threatening events
Autonomic aspect triggers fight or flight response
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Emotional responses + survival - cons
- Heightened emotional response can lead to impulsive decisions (eg. run quickly from a lion)
- This is good as speed is important
- BUT this will reduce accuracy + introduce errors
SO…
Heightened emotional response is not good for uni exams, cricket games etc. , where life is not in threat
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Lie detector - what does it use?
- Polygraph (respiration, sweat production, heart rate)
- Measures autonomic aspect of emotional response
