interfering with brain function Flashcards
brain stimulation
non-invasive technique using a magnet coil to induce a voltage or electrodes to induce current into brain tissue
two ways of interfering with brain function
transcranial magnetic stimulation (TMS)
- used to inhibit brain function
transcranial direct current stimulation (tDCS)
- use to facilitate brain function
causal uses of brain stimulation
neuroimaging cant provide causal evidence - only correlational
can be used to investigate causal functions of a target brain area
if stimulation in a specific area either increases or decreases performance, we can assume that area has a causal role in behaviour we are observing
TMS
uses a coil which creates an electromagnetic field
applied to top of head
buzzed into brain at different depths depending on the angle of the coils
- specific areas can’t be targeted
how does TMS create virtual lesions?
repetitive TMS creates virtual lesions
brain regions become temporarily impaired or disconnected
allows causal involvement in certain behaviours to be studied
area of brain becomes tired and impaired for a short period of time - experiments then done
control conditions in TMS experiments
usually same person does the same task at a different time
- sham condition
where a fake pulse us emit or a different brain region is affected (one not involved)
TMS and causal experiments
combine TMS with behavioural experiements
if brain region is causally linked to a specific function, TMS will cause a decrease in performance and reaction times compared to control
benefits of TMS
brain research
- precise localisation of brain regions
- can be used with EEG or fMRI
temporary brain impairments without long term consequences
- saves animals
- can study same person
medical research and application
- many therapeutic benefits
- eg depression and addictions
tDCS
non-invasive, painless brain stimulation
uses direct electrical currents to stimulate specific parts of the brain
constant, low intensity current passed through 2 electrodes placed over the head
modulates neuronal activity
anodal and cathodal stimulation
anodal and cathodal stimulation with tDCS
anodal - acts to excite neuronal activity
cathodal - inhibits or reduces neuronal activity
advantages of tDCS
cheap, non-invasive, painless
easy to administer and portable
minimal side effect
may be used for treatment of neuropsychiatric conditions
- depression, anxiety etc
can relieve symptoms related to language and movement disorders and impaired cognition
negatives of tDCS
long term consequences not clear
too easy so prone to abuse
2 roles of painkillers
depressing nervous system
makes it harder to pain signals to reach brain
attach to opiate receptors to block pain signals coming from body
how does paracetamol work?
blocks enzyme receptor in the brain but not in body
pain is there but mind won’t receive the message
how do NSAIDs work?
eg aspirin and ibuprofen
block an enzyme used by injured cells to prostaglandins (bodies pain messengers)
when cells don’t release prostatagladins, brain won’t get pain message as clearly to quickly
