The Biological Approach Flashcards
Brain and Behaviour - Brain Imaging Techniques
MRI
Magnetic Resonance Imaging
Produces static image of brain and used to detect stuctural changes in the brain.
High spatial resolution (highly detailed), low temporal resolution (cannot show activity).
Helps understand cognitive processes such as Memory.
Brain and Behaviour - Brain Imaging Techniques
fMRI
Functional Resonance Imaging
Shows physiological structures in great detail - shows action and functions within brain by blood flow measurement.
Low spatial resolution, high temporal resolution.
Brain and Behaviour - Brain Imaging Techniques
Advantages/Disadvantages of Brain Imaging Technology
Advantages
Non-invasive method to look into healthy and functioning human brains (compared to exploratory surgery).
Can help with early diagnosis and treatments of disorders.
Disadvantages
Expensive.
Claustrophobic.
Loud.
Brain and Behaviour - LOF
Localisation of Function
Different areas of the brain are associated with different behaviours.
Brain and Behaviour - LOF
Hippocampus
Involved in encoding STM into new LTM (declarative/explicit memories).
Brain and behaviour - Brain Imaging Techniques, LOF, Neuroplasticity
Grey Matter
Made up of neuronal cell bodies and synapses.
More grey matter, more synaptic connections/neural networks.
Study - LOF SAQ/ERQ
Milner et al (HM case study)
RM: Case study - 5 decades
Aim
Investigates the brain’s impact due to the removal of the hippocampus.
Background information
HM sustained a serious head injury at a young age and endured serious seizures throughout his younger years.
With his and familial approval, he participated in experimental surgery for removal of temporal lobe (w/ hippocampus).
Initial observations - After operation
Remembered childhood very well.
Forgot daily events nearly as fast as they occurred.
Method
MRI scans.
Kept re-introducing himself to people.
HM underwent various strategies:
Psychometric testing.
Direct observation.
Cognitive testing
- Memory recall.
- Learning tasks (e.g. reverse mirror drawing).
Results
Diagnosed with anterograde amnesia (inability to form new declarative/explicit memories).
Psychometric testing - Hippocampus does not influence IQ.
Direct Observation - Hippocampus plays a critical role in converting STM to LTM.
Cognitive Testing (Mirror task) - Skills improved, therefore hippocampus is not responsible for procedural/implicit memories.
MRI - Almost all of HM’s hippocampus was removed.
Study - Brain Imaging Techniques SAQ, Neuroplasticity SAQ/ERQ
Maguire et al
Human Quasi experiment
Aim
Investigating whether morphological changes in the brain could be detected in relation to extensive experience of spatial navigation.
Method
London taxi drivers were chosen because they relay heavily on spatial navigation skills in working lives. Also had to undertake extensive training called “The Knowledge” to acquire vast spatial memory of roads.
Numerous right-handed male licensed London taxi drivers were compared with scans of numerous age-matched right-handed males who do not drive taxis.
Results
MRI analysis found that significantly increased grey matter volume was found in only two regions of taxi drivers’ brains: right and left hippocampi compared to control group (no other differences).
Posterior hippocampi of taxi drivers was significantly larger than control group.
Anterior hippocampi of control group was significantly larger than taxi drivers.
Positive correlational analysis between time length as taxi driver and volume of right posterior hippocampus (negative for anterior).
Critical Thinking
Strengths
Well-operationalised dependent variable - MRIs give objective data.
High external (ecological) validity - Use of real taxi drivers.
Limitations
Generalisability - Only taxi-drivers/males; general population may not have same hippocampal changes (e.g. females).
Bidirectional ambiguity (correlational research often has this):
- Experience as a taxi driver causes hippocampal changes.
- People with naturally larger hippocampi may excel at spatial navigation.
- To counter: Conducted correlational analysis. Found that longer as taxi driver = Larger posterior hippocampus.
Study - Brain Imaging Techniques ERQ, Neurons SAQ
Arnone et al
Human True Experiment
Aim
To investigate the role of SSRIs in neurogenesis and role in reducing symptoms of depression.
Method - MRI
39 currently depressed (MDD), 25 in remission, 66 healthy controls underwent MRIs.
Results - MRI
Currently depressed patients had reduced grey matter in hippocampus compared with healthy and remission groups.
Method - Antidepressants
Most of currently depressed were treated with citolopram SSRI for 8 weeks.
After 8 weeks, patients’ hippocampi were measured again.
Results - Antidepressants
Depressed participants who were assigned to SSRI condition had increase grey matter with some experiencing decreased depressive symptoms.
Critical Thinking
Strengths
High internal validity (operationalised DV) - MRI isolated variable.
Limitations
Correlational; not causation.
Validity enhanced if there is a true control group.
- Random allocation of different groups from same depressed sample.
- May have not been done due to ethics (more ethical to give everyone treatments).
Study - Brain Imaging Techniques ERQ, LOF ERQ
Dunlop et al
Human correlational study.
Theoried that MDD is not unitary and that symptoms of depression might be better explained by underlying neural networks and ‘biotypes’ of depression.
Aim
To investigate the effectiveness of CBT and antidepressants for different biomarkers of depression.
Method
Numerous participants were assigned to SSRI or CBT condition.
Participants underwent resting-state fMRIs for baseline data.
Treated for 12 weeks and then treatment effectiveness was assessed using a depression rating scale and computer analysis using AI correlates patterns of brain connectivity with effectiveness of medications.
Results
When treatment matched biotype, 74% of participants improved.
When did not match, failed for 86%.
47.5% improved through treatment.
Critical Thinking
Helps explain why so many people with MDD struggle to find effective treatment.
Study - Neuroplasticity ERQ
Draganski et al
Human field experiment
Aim
Investigate whether juggling would affect the brain of participants.
Method
Mostly female young adult volunteers who were non-jugglers at start of study.
Separated into juggling and non-juggling (control) group.
Participants had MRI scan initially as base rate for grey matter/brain structure.
Juggling condition - Taught a three-ball juggling routine and asked to practice and notify researchers when they have mastered it.
At notification, underwent second MRI scan.
Results
Prior to juggling, no significant differences.
After second scan, jugglers had significantly larger amount of grey matter in mid-temporal area in both hemispheres (related to visual memory).
Three months after participants stopped juggling (unable to do routine), grey matter decreased.
Critical thinking
Strengths
Argues a causal relationship.
Limitations
IV manipulated under natural conditions, home environments may be different for participants affecting DV.
Generalisability - Use of volunteer; more motivated than general population.
Brain and Behaviour - Brain Imaging Techniques, Neurotransmitters.
MDD
Major Depressive Disorder.
Classified as a persistent low mood and/or anhedonia.
Other common symptoms include detrimental effects on sleep and appetite, impairment of daily functioning, and suicide ideation.
Brain and Behaviour - Neuroplasticity
Neuroplasticity
Changes in neural pathways and synapses due to changes in behaviour and environment.
Repeated activation of neural pathways make them stronger (structural changes).
Brain and Behaviour - Neuroplasticity
Neural networks
Interconnected groups of neurons that communicate with each other to carry out complex cognitive processes.
Formation of networks is dictated by neuroplasticity.
Specifically through synaptic plasticity (strengthening/weakening of synapses) and LTP (repeated activation of certain pathways lead to more efficient signal transmission).
Brain and Behaviour - Neuroplasticity
Synaptic Plasticity
Strengthening/weakening of synapses
Brain and Behaviour - Neuroplasticity
Long term Potentiation (LTP)
Repeated activation of certain neural pathways lead to a more efficient signal transmission.
Brain and Behaviour - Neuroplasticity
Neural Pruning
Brain eliminates unused synaptic connections and refines more commonly-used neural networks.
Essential for efficient brain functioning.
Can be studied by observing changes in grey matter.
Brain and behaviour - Neurotransmitters
Neurotransmitters
Neurotransmitters are chemical messengers that neurons use to communicate.
Mediates the events at the synapse between neurons.
Affected by agonists (amplies their effects) and antagonists (reduces their effects).
Brain and behaviour - Neurotransmitters
Serotonin
Serotonin (5-HT) is a neurotransmitter which modulates mood, sleep and appetite.
Brain and behaviour - Neurotransmitters
Excitatory neurotransmitters
Excites (activates) the neuron.
Brain and behaviour - Neurotransmitters
Inhibitory neurotransmitters
Prevents a neuron from firing.