Behaviour + neuroscience Flashcards
Neuroscience definition
- Not just the brain!
- Study of the STRUCTURE + FUNCTION of the NERVOUS SYSTEM!!
- NERVOUS SYSTEM:
1. Brain
2. Neurone
3. Synapses
Behaviour definition
- observable actions of humans + animals.
Behaviourism definition
- 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
Why does behaviourism not work alone? 2
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
Behavioural neuroscience
- BRAIN —> BEHAVIOUR + MIND (internal processes)
- How the brain CONTROLS the behaviour + mind!!
- Involves research on ANIMALS (since they mirror human behaviour)
What limits our understanding of the brain? 4
- 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
Behavioural neuroscience // Behavioural Physiology // physiological psychology // biological psychology
- IDENTIFY KEY WORDS = behavioural, physiology, biological
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
Neuropsychology(2 focuses)
Links BRAIN DAMAGE (LESIONS) with psychological processes
- CLINICAL
- Before surgery: assess risk - eg. would brain surgery impact…
- After surgery: assess impairments + improvements - RESEARCH
Psychopharmacology
NEUROCHEMISTRY in mind and behaviour
- Natural = neurotransmitters, hormones
- Artificial = drugs
Comparative neuroanatomy + psychology2
STUDYING DIFFERENCES + SIMILARITIES IN SPECIES TO EXMAINE….
- Brain EVOLUTION
- Origin and purpose of behaviours
Cognitive neuroscience
- Connects BRAIN with COGNITION (ie. memory, language, perception, decision making)
- Connects BRAIN REGIONS with FUNCTION
Cognitive neuroscience - what tool is commonly used?
- FUNCTIONAL brain imaging(fMRI)
Psychophysiology
- Now included in COGNITIVE NEUROSCIENCE
- Longer history, includes more BASIC RESPONSES like “startle”
Psychophysiology - what tool is commonly used?
- EEG
Neuromorphic computing
- Using electronic CIRCUITS to MIRROR neural STRUCTURES in the brain
Cognitive computational neuroscience
- AIM to characterize NEURAL COMPUTATIONS that underlie COMPLEX BEHAVIOUR
Silico neuroscience
- Use of computer modeling / simulations
- BROAD TERM
OUR CURRENT UNDERSTANDING
BRAIN → MIND (internal processes) + BEHAVIOUR
** Brain CONTROLS mind + behaviour
ANCIENT EGYPTIAN CULTURES 2
- 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
HIPPOCRATES 2
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
RENE DESCARTES
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
GALVANI
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
GALL
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
BROCA
- 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
Broca area - function
Language production
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
BRAIN - WHAT IS ITS WEIGHT? RELATIVE TO BODY?
- 1400 grams
- 3% of body weight
Brain - how many neurons + synapses + circuits?
- NEURONS = 100 billion
- SYNAPSES = 1,000,000 billion
- CIRCUITS = 10 to the power of 1 million
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)
Brain - information processing similar to?
- VERY similar to COMPUTER SYSTEM PROCESSING
Are humans special compared to other animals?
- NO!!
- Animal brains have SIMILAR STRUCTURES + NEUROTRANSMITTERS to humans
- Animals show similar BEHAVIOUR to us too
What makes an animal more intelligent?
- THE MORE NEURONS → more synaptic connections between neurons → more COMPLEX FUNCTION can be done → more intelligent
What DOES NOT make an animal more intelligent?
SIZE of the brain
- Eg. a dog is more intelligent than a big giraffe
- Even after considering relative size (ie. consider the animal’s body size), still not an indicator
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
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
Charles Darwin + behaviour across species - debate? 2
- Religious debates
- God gave morals to us, not old animals! - Moral debates
- Why should I be responsible for my greed/uncontrollable feelings if it’s from old animals?
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
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
Animals as models for human behaviour - why are MOUSE good for experiments?
- ADAPT to a variety of environments
- Only 8 WEEKS to develop fully
- Produce LARGE NUMBER OF OFFSPRING
- This also makes experiments cheaper, most cost-efficient - Offspring are SUPER SMALL
- Can be placed in tubs easily
- Lots can be stored at one time
Allen Brain institute
- Creates DETAILED MAPS
- Allows us to see brain areas, neurons, genes!
- Done by using data from mice + human brain
Human brain project
- Designing COMPUTER CHIPS to SIMULATE the human brain’s neurons + synapses
- Falls under “NEUROMORPHIC COMPUTING” (brain inspired computing)
Human brain project - why simulate the brain?
- Reduce the need for animal experiments
- Improve the validation of data + experiments w/ computational validation
- Study diseases in silico experiments
DIVISIONS OF THE NERVOUS SYSTEM
- Whole nervous system → PNS (peripheral) + CNS (central)
- PNS → somatic + autonomic
- Autonomic → enteric, parasympathetic, sympathetic
CNS - what does it consist of? 3
- Brain
- Spinal cord
- Retinal cells within the eyeball
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
VERTEBRAE - function
- Protection of the spinal cord
- Flexibility for the body when moving
PNS - GENERALLY what types of nerves what does it consist of 2
- Cranial nerves = nerves that connect to the brain
- Spinal nerves = nerves that connect to the spinal cord. Tend to run along the VERTEBRAE
PNS what does it consist of? 2 subdivisions
- Somatic nervous system
- Involves SKELETAL MUSCLE
- VOLUNTARY contractions - Autonomic nervous system
- Involves smooth muscle, cardiac muscle, glands
- INVOLUNTARY contractions (Eg. can’t think “make my heart beat faster”)
Somatic nervous system - 2 general functions
- Nerves INTO the CNS
- CNS RECEIVES signals (eg. body position, temp).
- Comes from SENSORY ORGANS - Nerves OUT from the CNS
- Brain SENDS signals
- Goes to SKELETAL MUSCLES, causes CONTRACTION
Peripheral sensory areas:
- LOCATION where SENSORY RECEPTORS are found.
- EG. skin, eyes, or ears
Sense modalities:
- Types of STIMULI detected by receptors.
- Eg. light, sound, or pressure
Somatic nervous system - 3 types of nerves
- EFFERENT, CRANIAL nerves → sends signals AWAY from the brain. Brain → contraction of muscle
- AFFERENT, CRANIAL nerves → sends signals INTO the brain. Stimulus detected by receptor → Brain
- Spinal nerves → sensory + motor pathways
Autonomic nervous system - 3 subdivisions
- Parasympathetic
- Sympathetic
- Enteric
Parasympathetic + Sympathetic? Relationship?
- OPPOSITE to each other
-Both impact important bodily functions + responses
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
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
Parasympathetic + Sympathetic - what are they driven by?
PARASYMPATHETIC
- Ach (acetylcholine)
SYMPATHETIC
- NA (Noradenaline)
- Adrenaline
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
Enteric nervous system (ENS) - what is it consisting of?
- The GUT
Enteric nervous system (ENS) - function?
- BASIC = digestion
- ANOTHER MAJOR ROLE = emotions + stress
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!
Enteric nervous system (ENS) - connection with the brain?
- So intelligent that…90% of connections/messages go FROM the gut TO THE BRAIN!!!
Anterior
Posterior
Superior
Inferior
Anterior = front
Posterior = back
Superior = top
Inferior = bottom
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
Lateral
Medial
Lateral = away from the midline
Medial = towards the midline
Ipsilateral
Contralateral
Ipsilateral = on the SAME SIDE of the midline
Contralateral = on the OPPOSITE SIDE of the midline
Callosotomy
PROCECURE of cutting the corpus collosum
- done to stop epileptic seizures
- by stopping communication between hemispheres
what is the largest structure of the human brain?
cerebral cortex
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
where is the midbrain and hindbrain located?
brainstem
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
What happens if the frontal lobe is damaged? 3
1) personality changed MASSIVELY
2) unable to plan
3) cannot make decisions
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.
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.
Excitatory postsynaptic potentials (EPSPs) - caused by what neurotransmitter?
Glutamate
- EXCITATORY neurotransmitter
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
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
Inhibitory postsynaptic
potentials (IPSPs) - caused by what neurotransmitter?
(GABA)
- INHIBITORY neurotransmitter
What are neuromodulators? 4 examples (no need to rlly memorise)
1) Dopamine
2) Noradrenaline
3) Serotonin
4) Histamine
Neuromodulators vs neurotransmitters
- FAR FEWER NEURONS relaying neuromodulators compared to neurotransmitters
eg. - only a few neurons will release serotonin (vs the whole brain)
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
How do drugs work?
- MIMIC the shape of neurotransmitters/neuromodulators
- so that it can FIT into the SPECIFIC shape of the receptor
Agonist
TYPE OF DRUG
- Has the same EXACT SHAPE as a neurotransmitter/neuromodulator
- Hence will ACTIVATE the receptor like normal
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
Do drugs have a large impact?
YES
- Drugs can impact every stage of neurotransmitter function
(synthesis of neurotransmitters, release of neurotransmitters, neurotransmitters + receptor binding)
AGONISTIC DRUG EFFECT 2
1) increase synthesis of neurotransmitters
2) increase release of neurotransmitters
ANTAGONISTIC DRUG EFFECT
1) blocks synthesis of neurotransmitters
2) blocks release of neurotransmitters
Brain imaging
- Assess brain STRUCTURE
- Done non-invasively - ie. without dissection/damage to the brain
Lesions
Brain damage
Neuropsychological methods
- Uses patients with brain damage to determine functions of the brain
- Eg. damaged hippocampus → infer its role in memory
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
Experiments of nature
- when Experimenters rely on naturally occurring brain injuries
- Not lab controlled
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)
EEG - electroencephalography + electroencephalogram
-Electroencephalography = equipment/method used
- Electroencephalogram = data received
- EEG refers to BOTH of these combined
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
EEG - data
- Electrical activity are electrical signals sent to the machine
- These signals are shown with spikes//peaks - height represents magnitude of electrical activity
EEG - uses
- Diagnoses epilepsy
- During seizures, electrical activity would be much higher
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
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
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
Electrophysiology - pros
Since detecting electrical activity in an INDIVIDUAL neuron, good if you want to know what the neuron is DOING
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
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)
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
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
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
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.
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
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
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
PET - importance?
buildup of certain chemicals / metabolism of certain chemicals can point towards and therefore diagnose certain diseases!
PET - pros 1
Detect chemicals in the brain specifically
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
Brain modification/modulation - 3 examples
1) Brain regions are removed/destroyed
2) Drugs
3) Electrical stimulation of brain regions
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
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
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
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)
Ablation studies - done on who?
- Humans = strictly medical treatment
- Animals = for research purposes
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
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
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.
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)
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
Non-invasive electrical stimulation - 2 types
1) ECT
2) tCDS
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)
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%
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
TMS - cons
- Painless unless it causes muscle contraction
- Eg. can cause arms to fly out
Drugs + brain modulation
- impact neurotransmitter function, therefore neural connections
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”
Synaptic connection / synapse
- Link between 2 neurons
- Includes presynaptic neuron, synaptic cleft, postsynaptic neuron
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
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
Brain plasticity - 2 examples
1) SYNAPTIC PLASTICITY
- Strengthening of synaptic connections
- Weakening/removal of synapses
- Generating new synaptic connections
2) NEUROGENESIS
Strengthening/weakening of synaptic connection - name of process?
STRENGTHENING =
Long term potentiation (LTP)
WEAKENING = Long term depression (LTD)
Do the LTP and LDP work tgth?
YES!!
- LTP and LDP are important together
- Helps the brain adapt to current needs
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
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!)
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
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!)
“Neurons that fire together wire together”
Repeated activation and firing of neurons = stronger synaptic connection
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!
Is the brain always active?
- Yes, even during sleep
- Allows you to CONSTANTLY maintain/strengthen/remove/weaken synaptic connections
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
Neurogenesis
- New neurons can be generated
- Used to replace dead neurons
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
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
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
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
Motor control - takeaway
- Lots of areas of the brain
- All highly integrated/connected via synapse connections
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
Why are feelings important? 2
1) Motivators
2) Expresses an animal’s intentions
Where have emotions come from?
Evolution, Charles Darwin
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
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
Emotional responses pros
- Survival in life threatening events
Autonomic aspect triggers fight or flight response
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
Lie detector - what does it use?
- Polygraph (respiration, sweat production, heart rate)
- Measures autonomic aspect of emotional response
