Psychology Chapter: The Brain and Behavior

The Brain and Behavior

• Localization of function is the theory that specific brain areas control specific functions, like aggression, attention, hunger, and embarrassment.
• Neuroplasticity describes the brain's ability to adapt its structure and function over time due to experience and genetics.
• Widely distributed functions aren't limited to a single brain region; they involve multiple interconnected areas.

HM Study (Milner, 1966)

• Aim: To understand the effects of surgery on patient HM.
• Procedure: Used a combination of cognitive tests, observations, interviews, and brain imaging.
• Findings: HM couldn't form new explicit memories (anterograde amnesia) but retained procedural memory. This supports the idea that memory functions are localized.
• Strengths: Used a rigorous, multi-method approach and observed HM over a long period.
• Limitations: Only one subject; limits generalizability. The study had ethical concerns regarding consent given HM's memory issues.

Maguire et al. (2000)

• Aim: To investigate whether structural brain changes occur in London taxi drivers due to extensive spatial navigation experience.
• Procedure: Compared MRI scans of taxi drivers and non-taxi drivers.
• Findings: Taxi drivers had a larger posterior hippocampus, while non-taxi drivers had a larger anterior hippocampus. This shows neuroplasticity in response to environmental demands.
• Strengths: Used advanced MRI technology, and compared a large sample.
• Limitations: A correlational study, making it difficult to conclude causation. Gender and cultural bias due to the specific sample.

Sperry and Gazzaniga (1967)

• Aim: To investigate the effects of hemisphere disconnection (severed corpus callosum) on cognition and behavior.
• Procedure: Split-brain patients were tested using visual and tactile tasks.
• Findings: The brain hemispheres operate independently. Specific functions (like language) are often localized to one hemisphere.
• Strengths: Used controlled laboratory conditions, offering insights into lateralization.
• Limitations: Small sample size and artificial tasks were limitations.

Neurotransmitters and Behavior

• Agonists enhance neurotransmitter activity, while antagonists inhibit it.
• Neurotransmitters are chemicals that transmit signals between neurons.
• SSRIs (Selective Serotonin Reuptake Inhibitors) are medications that increase serotonin availability, used primarily to treat depression.

Crockett et al. (2010)

• Aim: Investigate the role of serotonin in moral judgment.
• Procedure: Participants received either a placebo or a serotonin-increasing drug (SSRI) and completed moral dilemmas.
• Findings: Increased serotonin led to more aversion to harming others.
• Strengths: Double-blind design, avoiding bias. Clear operationalization of moral dilemmas.
• Limitations: Artificial scenarios limit ecological validity, and ethical considerations exist regarding drug administration.

Fisher et al. (2005)

• Aim: Study the neural mechanisms of romantic love.
• Procedure: Participants viewed images of romantic partners while undergoing fMRI scans.
• Findings: Romantic love activates dopamine-rich areas, like the ventral tegmental area (VTA).
• Strengths: fMRI provided detailed insights into brain activity.
• Limitations: Small sample size, and cultural biases in romantic norms.

Martinez and Kesner (1991)

• Aim: To investigate acetylcholine's role in memory formation.
• Procedure: Rats were trained in a maze; then injected with acetylcholine agonists or antagonists.
• Findings: Rats with enhanced acetylcholine performed better, while inhibited acetylcholine performed worse, linking this neurotransmitter to memory.
• Strengths: Used a controlled experiment and a replicable design.
• Limitations: Animal study limits direct application to humans. Animal testing also raises ethical concerns.

Hormones and Behavior (Newcomer et al., 1999)

• Aim: Investigate the effects of cortisol on verbal memory.
• Procedure: Participants received high, low, or placebo doses of cortisol and completed memory tests.
• Findings: High cortisol levels impaired memory performance, suggesting a link between stress and cognitive function.
• Strengths: Followed a double-blind, placebo-controlled design. Also included ethical considerations in the administration of the medication.
• Limitations: Study was short-term, and potential individual differences in stress responses exist.

Baumgartner et al. (2008)

Aim: Investigate the role of oxytocin in trust.

• Procedure: Participants played a trust game while receiving either oxytocin or a placebo.
• Findings: Oxytocin increased trust even after breaches, highlighting its role in social bonding.
• Strengths: Used an innovative approach with trust games; fMRI provided insights into neural mechanisms.
• Limitations: Artificial experimental setting, and the potential for ethical concerns.

Genes and Behavior (Caspi et al., 2003)

• Aim: To investigate the role of the 5-HTT gene in depression.
• Procedure: Genotyped participants and assessed them for depression after stressful life events.
• Findings: Individuals with a short allele of the 5-HTT gene were more likely to develop depression under stress.
• Strengths: Large sample size, groundbreaking work in gene-environment interaction.
• Limitations: Potential biases in self-reported measures of stress, and ethical concerns regarding genetic determinism.

Bouchard et al. (1990 and 1981)

• Aim: To Examine the genetic basis of intelligence.
• Procedure: Studied monozygotic and dizygotic twins, raised together and apart, assessing their IQ similarities.
• Findings: Monozygotic twins raised apart demonstrated very similar IQ scores, suggesting a strong genetic influence on intelligence.
• Strengths: Large, diverse sample of twins and comprehensive data collection.
• Limitations: Assumes equal environments for twins; correlation does not equal causation.

Explore the intricate relationship between brain structure and behavior through the theories of localization of function and neuroplasticity. Delve into the HM study by Milner and its implications on memory, underscoring the distinctions between explicit and procedural memory. This quiz will test your understanding of these fundamental concepts in psychology.