Paper 1 - Biological Approach - The Brain and Behavior - Localization of Function

Localisation of function (LOF)

The theory that specific parts of the brain are responsible for specific behaviours or cognitive processes.

Scanning techniques are used to observe this.

LOF continued

Some parts of the brain play specific roles in behavior. Therefore, damage to one part of the brain means there will be damage to brain function. However, many functions are widely distributed, meaning diff parts of the brain have to work together to create behavior.

LOF assumes there is a biological basis to behavior and that thoughts, actions and other behaviors are linked to a biological function

Main parts of brain

Cerebrum, cerebellum, limbic system and brain stem.

Brain stem

Responsible for life functions (e.g. breathing and heart rate)

Cerebellum

Role in balance and motor function, including speech production and learning (classically conditioned responses).

Cerebrum

Largest part of the brain, associated w/ high-order functions (e.g. thought). Divided into 4 lobes:

- Frontal lobe: associated w/ executive functions (planning, decision-making, speech)

- Occipital lobe: associated w/ visual processing

- Parietal lobe: associated w/ the perception of stimuli

- Temporal lobe: associated w/ auditory processing and memory.

Limbic system

'emotional brain'. Major focus of psychological research for its role in memory and emotion. Key components:

- Amygdala: involved in formation of emotional memory and fear responses.

- Basal ganglia: involved in habit forming and procedural memory.

- Hippocampus: responsible for transfer of STM to LTM.

- Hypothalamus: involved in homeostasis, circadian rhythm etc. and control of the automatic nervous system. Controls pituitary gland.

- Nucleus accumbens - involved in addiction and motivation.

Language centers of the brain

Broca and Wernicke's area

Broca's area

An area of the frontal lobe in the left hemisphere, responsible for speech production.

Damage to Broca's area causes Broca's aphasia (characterized by speech that is slow, laborious and lacking in fluency).

Broca's famous patient was called 'Tan' as it was the only word he could say. People w/ Broca's aphasia have difficulty w/ prepositions and conjuctions.

Wernicke's area

An area of the temporal lobe in the left hemisphere, responsible for language comprehension.

Wernicke described people who had no problem producing language but several difficulties understanding it, so that the speech they produced was meaningless.

When damaged, it results in Wernicke's aphasia. People who have Wernicke's aphasia will often produce neologisms (nonsense words) as part of their speech content.

Antonova - Aim

To see if scopolamine affected hippocampal activity in the creation of spatial memory.

Antonova - method

Sample of 20 healthy male adults, w/ a mean age of 28 years. Used a double blind procedure and ppts were randomly allocate to one of 2 conditions. They were injected w/ either scopolamine or placebo 70-90 mins before the experimental task.

The ppts were then put into an fMRI where they were scanned while playing the 'arena task' a complex virtual reality game in which the researchers observed how well the ppts were able to create spatial memories.

The goal was for ppts to navigate around an 'arena' w/ the goal of reaching a pole. After the locate the pole, the screen would go blank for 30s.

During this, ppts were told to actively rehearse how to get to the pole. When the arena reappeared, ppts were at a new starting point. They would have to use their new spatial memory to find the pole.

ppts were trained in the game prior to the experiment. The ppts memory was measured for 6 hours.

Repeated measures design - ppts returned 3-4 weeks later, receiving the opposite treatment to the original study.

antonova results

When ppts were injected w/ scopolamine, they demonstrated a significant reduction in hippocampus activation compared to when they received a placebo (they took longer to find the pole).

antonova conclusion

supports the theory of localization as they show how spatial memory is localized in specific parts of the brain (localization).

demonstrates how the hippocampus (part of the temporal lobe) is involved in the creation of spatial memories.

Antonova strength

+ the study used a repeated measures design, eliminating the effect of ppt variability. Furthermore, the study was counter-balanced as some ppts did the scopolamine condition first, and the others did the placebo condition first. This controls for order effects (e.g. practice and fatigue effect).

antonova weakness

- Although there was a higher rate of error in the scpolamine group, it was not a significant diff. The diff. in hippocampus activity was, however, significant. This means the task as designed may not have been the best for showing performance differences; w/o the use of the fMRI, there would have been no way to know that at the biological level, there was significant different in the 2 conditions.

maguire aim

To examine whether structural changes could be detected in the brain of people w/ extensive experience of spatial navigation.

maguire method

Quasi experiment

Structural MRI scans were obtained

16 RH male London taxi drivers participated; all had been driving for more than 1.5 years.

Scans of healthy RH males who did not drive taxis were included for comparison.

The mean age did not differ across the groups

maguire results

The posterior hippocampus of taxi drivers had an inc. vol of grey matter compared to the control groups, and their anterior hippocampi were smaller.Changes w/ navigation experiment - a positive correlation was found between the time spent as a taxi driver and the vol in the right prosterior hippocampus.

maguire conclusion

the findings suggest the hippocampus (part of the temporal lobe) is responsible for spatial memory.

The results provide evidence for structural differences, suggesting extensive practice w/ spatial navigation affects the hippocampus.

This could also mean the posterior hippocampus is involved when recalling previously learnt spatial info. The anterior is used to encode new spatial info.

This demonstrates the brain can change in response to environmental demands.

maguire strength

There was a high level of control in the study. Many extraneous variables were controlled, including the mean age, the handedness, and the gender of the 2 groups. Moreover, the scans of the 50 control ppts were selected from the same structural MRI scan database as the taxi drivers, suggesting the same MRI scanner was used. This inc. the validity of the results.

maguire weakness

The results only show a correlation. Since the study was a quasi experiment, a cause-effect relationship can't be established because the IV (brain of taxi drivers) wasn't manipulated, it was naturally occurring. It could be that people w/ bigger posterior hippocampi are attracter to careers that use their spatial abilities, including taxi driver. Therefore, the results only show a correlation, not a cause-effect relationship.

Counter argument: The positive correlation btwn no. of years spent as a taxi driver and vol. in the right posterior hippocampus.

Evaluation of theory (weakness)

There is contradictory evidence. Lashley conducted an animal study and trained rats to perform specific maze running tasks, and then lesioned varying portions of the rats cortex to try and identify the area of the brain where learning and memory were localised. However, he found that although the amount of cortical tissue removed had specific effects on acquisition and retention of knowledge, the actual isolation of the removed brain tissue had no significant effect. This led to him concluding memory and learning aren't localised but widely distributed across the cortex. Therefore, the theory of LOF can't explain Lashley's findings.

Evaluation of theory (strength)

+ LOF has applications. The technological advances that allowed us to understand the localization of brain function have also developed our understanding of how medication affects certain areas of the brain: fMRI scanning allows the investigation of regionally specific brain associated w/ the administration of medicines designed to change the activity in a certain brain area, especially people w/ brain diseases (e.g. Alzheimer's).