Biopsychology: Investigating The Brain Flashcards
FMRI:
• fMRI – Uses magnetic field and radio waves to monitor blood flow; it measures the change in the energy released by haemoglobin, reflecting activity of the brain (oxygen consumption) to give a moving picture of the brain; activity in regions of interest can be compared during a base line task and during a specific activity
EEGs
EEGs –
Electrodes are put on the scalp using a skull cap. Represents the brainwave patterns that are generated from the action of millions of neurones creating overall account of brain activity.
Provides, sensory, cognitive and motor data.
Diagnostic tool, as ARRHYTHMIC patterns of activity may indicate neurological abnormalities such as epilepsy and sleep disorders.
and detect neuronal activity directly below where they are placed; differing numbers of electrodes can be used depending on focus of the research
ERPs
ERPs –
electrodes are put on the scalp and detect neuronal activity (directly below where they are placed) in response to a stimulus introduced by the researcher
EEG data contains information about sensory, cognitive and motor events. These events are isolated using statistical test averaging techniques. (Statistical analysis of EEG data)
All extraneous brain activity from the original EEGs is filtered out leaving only the presentation of a specific sensory stimulus or motor task.
What remains is the event related response; general activity from original EEG-extraneous brain activity = specific neural response from a sensory stimulus or motor task.
These are linked to cognitive processes such as attention and perception.
Post-mortem examinations:
post-mortem examinations-
brain is examined after death to try and correlate structural abnormalities/damage to unusual disorders or behaviours.
Comparison with a neurotypical to see the extent of damage.
Evaluation of MRIs
fMRI captures dynamic brain activity as opposed to MRI/post-mortem examinations which purely show physiology
• interpretation of fMRI is complex and is affected by temporal resolution (5 second time lag after initial neurone is fired neural guide), biased interpretation and by the baseline task used.
High spatial resolution to the mm which aids localisation of function.
• fMRI research is expensive leading to reduced sample sizes which negatively impact the validity of the research
Evaluation of post mortems :
• post-mortem examinations may lack validity due to small sample sizes (as special
permission needs to be granted)
Eg. HM: couldn’t give this consent
• Reduced validity due to neuronal changes during and after death
Causal relationship not certain:
Unrelated trauma
Advantages of studying the brain:
advantages of investigating brain activity in humans rather than generalising from animal
lesion/single electrode recording studies (for validity and ethical reasons)
EEG Evaluation
Diagnosis of epilepsy (random bursts of electrical activity in the brain detected during sleep) and sleep disorders/ stages of sleep.
High temporal resolution, a millisecond, compared to fMRI.
No spatial resolution, crude and overgeneralised.
Not useful for pinpointing exact source of neural activity.
Can not identify activities originating from different but adjacent locations.
ERP Evaluation
They bring much more specificity to the measurement of no processes that could never be achieved using EEG data. As ERPs are derived from EEG measurements, they have excellent temporal resolution, especially compared to FMRI and this has led to the widespread use in the measurement of cognitive functions.
Researchers have been able to identify different types of ERP is and describe the precise role of these in cognitive functioning; the P300 component is thought to be involved in the allocation of attentional resources of the working memory.
Lack of standardisation between different research tasks. Make it difficult to confirm findings.
Not easy to eliminate extraneous material eg. Background noise (standardise)
Cortical reserve
A type of individual difference that affects the chances of a DFR. This suggests there are individual differences in neuroplasticity that the theory fails to acknowledge.
Draganski
Learning induced changes:
In the posterior hippocampus
And the parietal cortex presumably because of their exam.
Medina
Prolonged drug use: poorer cognitive functioning and increased risk of dementia later in life.
Ramacuandra
60-80% of amputees.
Dougherty
Cingulotomy: Cingulate gyrus removed
32 weeks, 33% successful and 14% partial
Of 44 patients
The success of this shows that symptoms and behaviours associated with serious mental disorders are localised.
Law of equipotentialiy
The ability regions of the brain to recover lost functions. Stroke victims being able to recover as not all functions are localised. This lends to the holistic theory that all parts of the brain are involved with all functions.
