Lecture 10 - Interfering with brain function Flashcards
What does TMS stand for?
Transcranial magnetic stimulation
What does tDCS stand for?
Transcranial direct current stimulation
What is brain stimulation?
Non invasive technique using a magnetic coil to induce a voltage or electrodes to induce current into brain tissue
What is brain stimulation used for?
To investigate the causal function of a target brain area
See how behaviour changes if we interfere with a brain function, rather than just measuring it.
What is TMS?
a non-invasive procedure that uses magnetic fields to stimulate the brain
What is the control condition for TMS?
Sham condition
Where a fake pulse is emitted or a different brain region is affected
What are virtual lesions?
Created by TMS
Brain regions become temporarily impaired or disconnected
Allows us to study the causal involvement in certain brain functions in behaviour.
How do we test the causal contributions?
Combine TMS technique with carefully designed behavioural experiments
If the brain region is causally involves in a certain function, TMS will …
cause difference in performance (errors) and speed (reaction times) compared to a control condition
What are the benefits of TMS?
Brain research
Medical research
How does TMS help with brain research?
- Precise localisation of brain regions
can also be used in combination with eeg or fmri - Temporary brain impairment without long term consequences
saving lives of test animals
study brain function disruption in the same person
How does TMS hep with medical research?
Many therapeutic benefits of TMS for conditions including:
- depression
- addiction
- stroke rehabilitation
- parkinsons
- chronic pain
What is tCDS? How does it work?
Non invasive painless brain stimulation treatment that uses direct electrical currents to stimulate specific parts of the brain
Constant low intensity current is passed through two electrodes placed over the head which modulates neural activity
What are the two types of stimulation with tDCS?
Anodal stimulation - acts to excite neuronal activity
Cathodal stimulation - inhibits or reduces neuronal activity
What are the advantages of tDCS?
- cheap, non invasive, painless
- easy to administer and portable equipment
- minimal side effects
- valuable for treatment of neuropsychiatric conditions such as depression, anxiety, parkinsons, chronic pain, brain injury, and relieving symptoms of language and movement disorders
- cognitive improvement
What are the disadvantages of tDCS?
- too easy and too promising
- prone for abuse
- long term cognitive consequences not clear
How do painkillers work?
- depress nervous system, making it harder for pain signals to reach the brain
- attaching to opiate receptors to block pain signals coming from the body
What are NSAIDS and how do they work?
E.g. Aspirin and ibuprofen
Block an enzyme used by injured cells to make prostaglandins (pain messengers).
How does paracetamol work?
Treats pain by blocking the enzyme receptors in the brain, meaning the pain is there but your mind does not receive the message.
What are beta blockers?
Block the effects of stress hormones such as adrenaline and noradrenaline to reduce physical signs of anxiety like decreasing heart rate
e.g propranolol
Disadvantages of beta blockers (propanolol)
Can also supress positive stress which can result in loss of libido, erectile dysfunction and depression
What are the cognitive effects of beta blockers?
can impact perception and motor function, may improve complex task performance
What are examples of widely socially acceptable stimulants?
Caffeine and Nicotine
How does caffeine work?
Mimics adenosine (neurotransmitter that causes drowsiness) and attaches to adenosine receptors in the brain. Caffeine blocks receptors making us feel more alert
What are the cognitive effects of caffeine?
Improves attention, reaction time, and mood
How does nicotine work?
Increases the release of dopamine and adrenaline. Dopamine is a reward messenger that causes feelings off pleasure and improved mood. The rush of adrenaline stimulates the body and causes an increase in blood pressure, respiration and heart rate, can result in anxiety.
What are the cognitive effects of nicotine?
Improve attention, learning, fine motor skills and memory, lead to a cognitive decline in middle age
What are medical and illicit stimulants?
Increase psychomotor and sympathetic nervous system activity, improve alertness and mood by increasing adrenaline and dopamine
Rapid uptake - rapid short lived reward
What are the medical and recreational applications of stimulants?
Increase heart rate, constrict blood vessels, dilate pupils, inhibit salivation & digestion, ease nasal congestion, appetite suppression, hyperthermia
What are the cognitive effects of medical stimulants?
enhance cognitive control, memory and attention
What are amphetamines and give examples?
Stimulants that improve sustained attention, reduce overactivity and impulsiveness
- ADHD drugs
- MDMA
- Crystal meth
What is cocaine?
Local anaesthetic that restricts blood vessels
What are hallucinogens/psychedelic drugs?
Drugs that indcuce reality atlering experiences
What are the 2 types of hallucinations?
True hallucinations- perception of images or sounds that are not real
Pseudo-hallucinations - altered perception of things that are real
What are the side effects of hallucinogens?
9% of adults use
Often have mood disorder in addition to substance, eating or personality disorders
Is there a medical use for hallucinogens?
Currently in experimental trials for treatment of depression
How do hallucinogens work?
Most target serotonin receptors.
Serotonin modulates mood, cognition, reward, learning, memory and numerous physiological processes.
What are the cognitive effects of hallucinogens?
Perceptual distortions, cognitive restructuring, mood changes, changes in meaning of perceptions, dissolution of bodily boundaries.
