3.6 Slides

Chapter 3: Neuroscience and Behavior

Introduction

  • Quote: "Thoughts become perception, perception becomes reality. Alter your thoughts, alter your reality." - William James

Methods of Investigating the Brain

Brain Damage

  • Principle: Correlates the loss of specific functions (perceptual, motor, emotional, cognitive) with areas of brain damage.

Case Study: Phineas Gage (1848)

  • Incident: Explosion drove a metal rod through his head.

  • Outcome: Drastic change in personality post-accident, affecting connections between the frontal lobe and limbic system.

Brain Organization

  • Control Mechanism: Contralateral control (right hemisphere controls left body and vice versa).

  • Verbal Abilities: Typically localized in the left hemisphere.

Hemispheric Functions

  • Left Hemisphere: Controls writing, language, logic, mathematical abilities.

  • Right Hemisphere: Controls emotional expression, spatial awareness, creativity, holistic thinking.

Split Brain Procedure

  • Method: Severing the corpus callosum.

    • Allows study of information processing between hemispheres.

    • Information presented to left hemisphere can be verbally described, while right hemisphere cannot.

Chimeric Faces Experiment

  • Participants point to and identify faces presented to left or right visual field, demonstrating hemispheric differences in processing.

Wada Test

  • Definition: Intracarotid sodium amobarbital procedure (ISAP) used to establish language representation in each hemisphere, particularly for epilepsy patients.

  • Mechanism: Injection freezes one hemisphere for language testing.

Hemispatial Neglect

  • Condition: Usually follows a stroke in the right hemisphere.

  • Symptoms: Lack of awareness/attention to the left side of the body or space; patients are often unaware of their condition.

Brain Imaging Techniques

Structural Brain Imaging

  • Definition: Provides information about brain structure and abnormalities.

Computerized Axial Tomography (CT) Scan

  • Uses x-ray photos at different angles to show tissue density.

  • Useful for locating tumors.

Magnetic Resonance Imaging (MRI)

  • Method: Brief magnetic pulses and recorded absorption to reveal brain structures.

  • Advantage: Better resolution of soft tissue compared to CT scans.

Functional Brain Imaging

  • Definition: Provides information about brain activity during cognitive/motor tasks.

Positron Emission Tomography (PET)

  • Procedure: Radioactive substance injected into the bloodstream; activates areas of the brain recorded by radiation detectors depending on blood flow.

Functional Magnetic Resonance Imaging (fMRI)

  • Mechanism: Detects oxygenated hemoglobin levels in blood, offering time-sensitive activation levels in the brain.

Transcranial Magnetic Stimulation (TMS)

  • Function: Delivers magnetic pulses to deactivate neurons in the cortex.

  • Application Example: TMS to the visual cortex may impair reaching accuracy for moving objects.

Conclusion

  • These methods provide valuable insights into brain function, structure, and the relationship between neurological activity and behavior.