2.1 Localisation

What is localisation of function

The idea that every behaviour is associated with a specific brain region

What is the name of the research supporting strict localisation

Paul Broca (1861)

What did Broca (1861) find

Tan from the loss of articulated speech.

Autopsy on tan's brain

lesion in the posterior inferior front gyrus. (Broca's Area)

What discovery did Broca inspire

Wernicke's area - Carl Wernicke 1874

Research opposing Localization

Karl Lashley (1890-1958)

What did Lashley conclude

Memory was distributed rather than localized (via the study of induced brain damage in rats)

Example of localisation

Amygdala - responsible for processing emotions and emotional memories.

Strict localisation

specific functions are localized to specific regions

Weak localisation

different brain regions are involved in different aspects of a function.

Relative localisation

certain functions are more likely to be found in certain regions of the brain (currently the most scientifically supported)

Lateralization

The division of function between the two hemispheres of the cortex.

How to investigate localisation

investigated through the use of neuroimaging techniques such as fMRI

Functional Magnetic Resonance Imaging (fMRI)

A type of MRI that is used to measure and map brain activity by detecting changes in blood flow.

Sharot et al. year

2007

Aim

To determine the potential role of biological factors on flashbulb memories

Method

Quasi Experiment

Design

Independent Measures

Sampling Strategy

Purposive (24 participants)

IV

Downtown or Midtown Manhattan

DV

Activation of the amygdala

Procedure 1

participants placed in an fMRI
Words placed on screen

Summer or September along with words

Procedure 2: Rate

After recall, participants were asked to rate memories:

Vividness
Confidence in accuracy
Arousal
Detail

Procedure 3

Participants were also asked to write down personal memories

Control

Summer recall was used as a baseline

Findings 1: FBM

• Only half of the participants actually reported having ‘flashbulb memories’

Findings 2: Proximity

• Those who reported flashbulb memories also reported they were closer to the attacks.

• Also included more specific details in their written memories

Findings 3: DT or MT

Downtown = higher activation of the amygdala when attack recalled than when summer recalled

Midtown = similar activation of the amygdala when recalling both events

Conclusion 1

Strength of amygdala activation shown to correlate with flashbulb memories

Close personal experience = critical in engaging neural mechanism that produce flashbulb memories

Evaluation: (strengths)

• Demand characteristics are not possible = increased internal validity

Evaluation: (weaknesses)

• Correlational = no cause and effect

• high artificial environment = low ecological validity

• Small sample size and culturally biased = research shows individualistic cultures are more likely to have flashbulb memories than collectivistic = hard to generalize

For a ERQ about localisation, which study should be used with Sharot el al. (2007)

Maguire et al.

Maguire et al. year

2000

Aim

To investigate whether the brains of London taxi drivers would be somehow different due to their deep city knowledge and extensive driving hours in London

Method

Natural Experiment

Design

Independent Measures

Single Blind

Sampling Strategy

Purposive; 16 right-handed London taxi drivers/50 right-handed males who did not drive taxis.

Selection Criteria

• Completed the ‘knowledge’ test

• Had their license for a least 1.5 years

IV

Whether they were a London taxi driver or not

DV

Mass and Distribution of Grey Matter in the Hippocampus

Procedure: 1

Data from MRI measured using two different techniques:

VBM - to measure density of GM

Pixel counting - counting pixels to measures area

Findings: Pixel Counting

Pixel counting = posterior hippocampi taxi - significantly larger

anterior hippocampi significantly smaller

Findings: VBM

Volume of right posterior hippocampi - correlate with time spent as taxi driver

Findings: 3

No differences observed in other parts of the brain

Conclusion

Maguire argues: demonstrates hippocampus may change in response to environmental demands

Conclusion: 2 - anterior posterior

Posterior Hippocampus - involved when previously learn spatial info used
Anterior hippocampus - encoding new environmental layouts

Evaluation: Methodological Strengths

Ethically sound - MRI no health risks

Coded brains scans= blind analysis - avoiding researcher bias

Evaluation: Methodological Weaknesses

Quasi-experiment - no cause-and-effect