Biological Bases of Behavior and States of Consciousness: Study Notes

Biological Bases of Behavior

Broca’s Area and Wernicke’s Area

Broca’s area and Wernicke’s area are two critical regions in the brain associated with language processing.

• Broca’s Area: Located in the left frontal lobe, this area is responsible for speech production and articulation. Damage to Broca’s area results in Broca’s aphasia, characterized by slow, halting speech and difficulty in forming complete sentences.

• Wernicke’s Area: Found in the left temporal lobe, Wernicke’s area is essential for language comprehension. Damage here leads to Wernicke’s aphasia, where speech is fluent but often nonsensical, and understanding language is impaired.

• Example: A patient with Broca’s aphasia may say, “Walk dog,” instead of “I will walk the dog.”

Phineas Gage

Phineas Gage was a railroad worker who survived a severe brain injury that dramatically changed his personality and behavior, providing early evidence of the role of the frontal lobes in personality and decision-making.

• Key Point: Gage’s accident demonstrated that specific brain regions are linked to particular psychological functions, especially those related to personality and impulse control.

• Example: After his injury, Gage became impulsive and unreliable, highlighting the frontal lobe’s role in regulating behavior.

Mapping the Brain

Various techniques are used to study the structure and function of the brain:

• Lesioning: Deliberate destruction of brain tissue to study the effects on behavior.

• CT (Computed Tomography): Uses X-rays to create detailed images of the brain’s structure.

• PET (Positron Emission Tomography): Measures brain activity by detecting radioactive tracers.

• MRI (Magnetic Resonance Imaging): Uses magnetic fields and radio waves to produce high-resolution images of brain anatomy.

• fMRI (Functional MRI): Measures brain activity by detecting changes in blood flow.

• EEG (Electroencephalogram): Records electrical activity of the brain via electrodes placed on the scalp.

Neurotransmitters and Disorders

Neurotransmitters are chemical messengers in the brain that influence various psychological disorders.

• Dopamine: Linked to schizophrenia (excess) and Parkinson’s disease (deficit).

• Serotonin: Associated with depression, anxiety, and mood disorders.

• Norepinephrine: Involved in mood and arousal; imbalances can lead to depression or anxiety.

• GABA: Inhibitory neurotransmitter; low levels are linked to anxiety disorders.

Consciousness

States of Consciousness

Consciousness refers to our awareness of ourselves and our environment. It includes various states such as wakefulness, sleep, dreaming, and altered states induced by substances or meditation.

• Normal waking consciousness: Alertness and awareness of thoughts, feelings, and sensations.

• Altered states: Sleep, hypnosis, meditation, and drug-induced states.

Sleep Stages and Sleep Disorders

Sleep is divided into several stages, each characterized by distinct brain wave patterns and physiological changes.

• NREM Sleep: Includes stages 1-3, progressing from light to deep sleep.

• REM Sleep: Rapid Eye Movement sleep, associated with vivid dreams and increased brain activity.

• Sleep Disorders: Common disorders include insomnia (difficulty falling or staying asleep), narcolepsy (sudden sleep attacks), and sleep apnea (breathing interruptions during sleep).

Brain Waves During Wakefulness and Sleep

Brain activity during sleep and wakefulness is measured by EEG and is characterized by different types of brain waves:

• Beta waves: Present during wakefulness and active thinking.

• Alpha waves: Associated with relaxed wakefulness.

• Theta waves: Seen in light sleep (Stage 1 and 2).

• Delta waves: Dominant in deep sleep (Stage 3).

Dream Interpretation (Freud)

Sigmund Freud proposed that dreams are a form of wish fulfillment and contain hidden meanings.

• Manifest Content: The actual storyline or events of the dream.

• Latent Content: The hidden psychological meaning of the dream.

• Why do we dream, according to Freud? Freud believed dreams allow unconscious desires and conflicts to be expressed in a disguised form.

Narcolepsy and Sleep Apnea

These are two significant sleep disorders:

• Narcolepsy: Characterized by uncontrollable episodes of falling asleep during the day, often at inappropriate times.

• Sleep Apnea: Involves repeated interruptions in breathing during sleep, leading to poor sleep quality and daytime fatigue.

Elements of Dependency

Dependency on substances can be physical or psychological and involves several key elements:

• Physical dependence: The body adapts to the drug, leading to tolerance and withdrawal symptoms.

• Psychological dependence: Emotional or mental need for the drug to function or feel good.

• Tolerance: Increasing amounts of the substance are needed to achieve the same effect.

• Withdrawal: Physical and psychological symptoms that occur when the drug is reduced or stopped.

Positive and Negative Reinforcement in Dependence

Reinforcement plays a role in the development of substance dependence:

• Positive Reinforcement: Using a substance produces pleasurable effects, increasing the likelihood of repeated use.

• Negative Reinforcement: Using a substance removes unpleasant feelings (e.g., anxiety, withdrawal), also increasing use.

• Conditioning: Environmental cues can trigger cravings and reinforce substance use behavior.

Psychoactive Drugs

Psychoactive drugs alter perception, mood, and behavior. They are classified into several categories:

• Stimulants: Increase activity in the nervous system (e.g., caffeine, nicotine, amphetamines, cocaine).

• Depressants: Decrease nervous system activity (e.g., alcohol, barbiturates, benzodiazepines).

• Narcotics/Opioids: Relieve pain and induce euphoria (e.g., morphine, heroin, codeine).

• Marijuana: Has both depressant and hallucinogenic properties; active ingredient is THC.

• Hallucinogens: Cause perceptual distortions (e.g., LSD, psilocybin).

• Barbiturates: A type of depressant used for anxiety and sleep disorders, but with high risk of dependence.

Morphine and Heroin

Morphine and heroin are opioids that duplicate the action of endorphins, the body’s natural painkillers.

• Key Point: These drugs bind to opioid receptors in the brain, producing pain relief and feelings of euphoria.