Biopsychology - 05 LoF & Plasticity And Functional Recovery Flashcards
Prior to the 19th century what theory did scientists support of the brain?
holistic theory, that all parts of the brain were involved in the processing of though and action
What is localisation of function?
The idea that certain functions like language, memory etc have certain locations in the brain
What is the outer layer of the brain?
Cerebral cortex
The cortex of both hemispheres are divided into how many lobes?
4
What are the 4 lobes in the brain?
-Frontal lobe
-Parietal lobe
-Occipital lobe
-Temporal lobe
What has two things have supported the idea of localisation of function?
-neuroimaging
-case studies
Explain the case study of Phineas Gage
-1848 while working on rail line had a piece of iron go through his skull
-Although he survived he experienced a change in his personality
-provides evidence to support the theory of localisation of function as it was believed that the frontal lobe (where the iron stake caused damage) was responsible for personality
What area is located in the frontal lobe?
motor area
What is the frontal lobe responsible for?
-voluntary movements by sending signals to the muscles in the body
What did Hitzig & Fritsch (1870) discover that links to the motor area?
-Different muscles are coordinated by different areas of the motor cortex by electrically stimulating the motor area of dogs
-This resulted in muscular contractions in different areas of the body depending on where the probe was inserted
How are the regions of the motor cortex arranged?
A logical order
the region that controls finger movement is located next to the region that controls the hand and arm and so on
What happens when there is damage to the motor area?
loss of control over fine movements
What area is located in the parietal lobe?
Somatosensory area
What is the parietal lobe responsible for?
receiving incoming sensory information from the skin to produce sensations related to pressure, pain and temperature
What did Robertson (1995) find that links to the somatosensory area?
this area of the brain is highly adaptable, with braille readers having a larger somatosensory area for their fingertips compared to normal sighted participants
What area is located at the back of the occipital lobe?
visual area
What is occipital lobe responsible for?
Receives and processes visual information and has different parts that process different types of information including colour, shape or movement
What area is located in the temporal lobe?
auditory area
What is the temporal lobe responsible for?
analysing and processing acoustic information
also contains different parts, the primary auditory area is involved in processing simple features of sound including volume, tempo and pitch
What are the 2 language centres?
Broca’s area
Wernicke’s area
Where is Broca’s area located?
back portion of the frontal lobe of the left hemisphere
How was Broca’s area discovered?
-Broca has a patient called Tan who was unable to speak other words other than ‘Tan’ but he did understand language
-post-mortem exam showed a lesion to the left frontal of Broca’s area
-This lead to him identifying the existence of a language centre critical for speech production
What does damage to Broca’s area lead to?
Broca’s aphasia which is characterised by speech that is slow, laborious and inarticulate
Where is Wernicke’s area located?
The back portion of the left temporal lobe
What is Wernicke’s area associated with?
Understanding language
Lesions to Wernicke’s area causes what?
Wernicke’s aphasia the ability to speak but no ability to understand language
patients will often produce nonsense words
Case study of Tan by Broca (evaluation of LoF)
S- supports
P- tan lost ability to speak but was able to understand speech, in post-mortem damage left frontal lobe
E- left frontal lobe responsible for functions of speech. subsequent research of similar damage and brain scans confirmed findings + reliability
L- confirms findings supporting LoF
Case study of EB by Danielli at al (evaluation LoF)
S- refutes
P- removed left side of brain lost language, 2 years later recovered fMRI showed right acted as left hemisphere
E- left hemisphere speech, but right was able to adapt and control language. EB young so not same as older people possibly
L-supports (without left no speech) but refutes (right adapted to act as left so function can be restored in different area)
Lashley (evaluation of LoF)
S- refutes
P-removed parts of cortex of rats learning maze found no area had bigger impact it was the size of removed area that did
E- learning requires every part of cortex, but was conducted on rats so need to be cautious when generalising to humans
L- refutes should have more holistic approach or LoF may not apply for learning as it is complex
Brain scan evidence Peterson et al (evaluation of LoF)
S- supports
P- Wernicke’s area active during listening task Broca’s area active during reading task so have different functions
E- Broca’s area in charge of reading and Wernicke’s area in charge of listening but might not be the case for other activities
L- supports 2 areas have 2 different functions
What is plasticity?
the brain’s ability to change and adapt (functionally and physically) as a result of experience and new learning
What are the 4 reasons for plasticity?
-Learning new skills
-Developmental changes
-Response to direct trauma to area of brain
-Response to indirect effects of damage such as brain swelling or strokes
How does plasticity work?
1-Gain new experiences
2-Frequently used nerve pathways get stronger
3-Synaptic pruning (neurons that are rarely used die)
4-Brain in a continued state of change
What did Boyke et al (2008) find?
-60-year-olds taught new skill, juggling
-found increases in neural growth in visual cortex
-when practicing stopped this was reversed
What is an example of plasticity being negative?
Prolonged drug use leads to poorer cognitive functioning
Maguire, 2000 (brain plasticity)
-16 healthy, right-handed male licensed London taxi drivers MRI compared with 50 healthy right-handed males who did not drive taxis
-Posterior hippocampi of taxi drivers significantly larger
-Size of posterior hippocampus was positively correlated with amount of time spent as taxi driver
-suggests physical structure of brain is plastic and able to adapt
Limitation of Maguire’s research
-Taxi drivers hippocampus size not tested before they became taxi drivers so we have no way of knowing id their larger size was due to completing the knowledge test and having experience or a pre-existing difference
-However the positive correlation makes the original conclusion more likely
Kemperman et al, 1998 (brain plasticity)
-investigated whether enriched environment can alter the number of neurons in the brains of rats
-Found evidence of increased number of new neurons (particularly in the hippocampus) in rats housed in complex environments compared to lab cages
-supports because brains changed because of their experience
Strength of Kemperman’s research
-scientific design
-rats studied before and after the change in environment
-so cause and effect can be shown in relation to changes of the brain due to experience
Limitation of Kemperman’s research
-poor ability to generalise the results from rats to humans
-significant differences in terms of complexity of human behaviour and experinces
Strength of research into brain plasticity
Practical application
-has contributed to the field of neurorehabilitation
-following illness or injury to the brain, spontaneous recovery tends to slow down after a number of weeks so forms of physical therapy may be needed to maintain improvements in functioning
-can then be used to help people return to their lives & productive work, ultimately benefiting the wider community
What are some of the techniques used in neurorehabilitation?
movement therapy
electrical stimulation
