Cognitive neuroscience and historical development of brain investigation

Cognitive neuroscience involves linking human behaviour to specific brain functions. It uses various methods to explore these connections, providing insights into how brain activity relates to actions and thoughts.

Methods used in cognitive neuroscience

• Lesion studies - Examine behavioural changes following brain damage in specific areas.
• Electrophysiology - Measures electrical activity in the brain during tasks.
• Neuroimaging - Visualises brain structure and function to identify active regions during behaviours.

Historical approaches to investigating brain structure

Early studies often relied on case studies of people with brain injuries or surgical interventions. For instance, damage to the frontal lobe from an accident led to personality shifts, such as reduced organisation and heightened impulsivity. If damage in a particular brain region consistently linked to behavioural alterations, researchers inferred a functional connection.

Limitations of lesion studies

• Lack of representativeness - Findings from individual cases may not apply to the wider population.
• Generalisation issues - Results are hard to extend beyond the specific case.
• Absence of control - Injuries occur outside laboratory settings, reducing scientific rigour.
• Ethical constraints - Deliberate brain damage cannot be inflicted for research.
• Species differences - Animal studies have limited relevance due to variations between human and animal brains.

Brain scanning techniques

Brain scanning techniques allow detailed examination of brain structure and function, helping to map behaviours to neural activity. These methods vary in their focus on structure, function, or both.

Types of brain scanning techniques

• Positron emission tomography (PET) scans - Detect active brain areas during tasks by tracking radioactive tracers, showing average activity over approximately 60 seconds and linking regions to specific functions like thinking.
• Computerised axial tomography (CAT) scans - Identify structural issues such as damage, tumours, or blood clots but do not reveal functional activity.
• Magnetic resonance imaging (MRI) scans - Offer detailed images to detect small tumours and provide structural information.
• Functional MRI (fMRI) scans - Combine structural and functional data to show brain activity in real time.
• Superconducting quantum interference device (SQUID) magnetometry - Measures magnetic fields from neuron activity for precise images, though external magnetic interference can distort results.

Research evidence on brain structure and applications to psychological areas

Research using brain imaging has demonstrated how experiences can physically alter brain structure, with implications for various psychological domains. A key study illustrates this through changes in taxi drivers' brains due to navigational demands.

Maguire et al. (2000) study of taxi drivers' brains

• Method - A natural experiment using MRI scans to compare 16 licensed male London taxi drivers (minimum 18 months experience, average age 44, all with normal neurological and psychiatric health) against a matched control group.
• Results - The right posterior hippocampus was notably larger in taxi drivers, with size positively correlated to years in the job.
• Conclusion - The hippocampus handles spatial memory; extensive navigation reshapes this brain area, indicating that cognitive demands can cause structural adaptations.
• Evaluation - Demonstrates potential for brain plasticity in rehabilitation; well-controlled and replicable for reliability; however, small sample limits breadth, and findings mainly apply to male London taxi drivers.

Applications of brain structure research to psychological areas

• Aggression and brain structure - Bard and Mountcastle (1948) observed that lesions in cats' brains modified aggression, implicating the hypothalamus and amygdala in regulating aggressive responses.
• Memory and brain structure - Milner et al. (1957) studied patient HM, who lost effective long-term memory formation after surgery, highlighting the hippocampus's key role in memory processes.
• Psychopathology and brain structure - Szeszko et al. (1995) identified prefrontal cortex variations in individuals with schizophrenia compared to those without, suggesting structural differences contribute to the disorder.

Neurochemistry and behaviour

Neurochemistry explores the nervous system's chemical processes, particularly neurotransmitters, and their influence on behaviour. The biological approach emphasises how imbalances can explain psychological issues.

Role of neurotransmitters in behaviour

Neurotransmitters are chemicals that transmit signals across synapses. Imbalances may lead to disorders; for example, high dopamine levels are associated with schizophrenia symptoms. Drugs that elevate dopamine can mimic schizophrenia-like effects, supporting the link between neurochemistry and mental health.

Strengths and weaknesses of the biological approach

The biological approach offers a scientific lens on behaviour but has notable limitations in scope and implications.

Strengths of the biological approach

• Scientific foundation - Generates empirical evidence to validate or refute theories about behaviour.
• Treatment applications - Identifies biological roots of issues, enabling targeted interventions like medication for mental health conditions.

Weaknesses of the biological approach

• Ignores non-biological factors - Overlooks influences such as environment, family dynamics, early experiences, or social contexts.
• Reduces accountability - May diminish personal or societal responsibility for harmful behaviours by attributing them solely to biology.