Biological Psychology

The Central Nervous System (CNS) and Peripheral Nervous System (PNS)

The nervous system is divided into the central and peripheral systems, each with distinct roles in processing and transmitting information throughout the body.

• Central Nervous System (CNS): Composed of the brain and spinal cord; responsible for integrating sensory information and responding accordingly.

• Peripheral Nervous System (PNS): Connects the CNS to limbs and organs. It is further divided into the somatic and autonomic systems.

• Somatic Nervous System: Controls voluntary movements of skeletal muscles.

• Autonomic Nervous System: Regulates involuntary body functions (e.g., heartbeat, digestion). It has two main branches:

  • Sympathetic Nervous System: Prepares the body for 'fight or flight' responses (increases heart rate, dilates pupils).

  • Parasympathetic Nervous System: Promotes 'rest and digest' activities (slows heart rate, stimulates digestion).

• Interneurons: Neurons within the CNS that connect sensory and motor pathways, facilitating communication.

Example: When startled, the sympathetic system increases your heart rate; when calm, the parasympathetic system slows it down.

Brain Structure and Function

The brain is organized into specialized regions, each with unique functions.

• Lobes of the Brain:

  • Frontal Lobe: Involved in reasoning, planning, movement, and problem-solving.

  • Parietal Lobe: Processes sensory information such as touch, temperature, and pain.

  • Occipital Lobe: Responsible for visual processing.

  • Temporal Lobe: Involved in auditory processing and memory.

• Limbic System: A group of structures (including the amygdala and hippocampus) involved in emotion, motivation, and memory.

• Amygdala: Plays a key role in processing emotions such as fear and aggression.

• Corpus Callosum: A bundle of nerve fibers connecting the two hemispheres of the brain, allowing communication between them.

• Association Areas: Regions of the cerebral cortex involved in higher mental functions such as learning, remembering, thinking, and speaking.

• Speech and Hemispheric Specialization: For most people, language functions are primarily located in the left hemisphere.

• Split-Brain Research: Studies of patients with severed corpus callosum reveal how the two hemispheres process information independently.

• Pituitary Gland: Known as the 'master gland' because it regulates other endocrine glands and controls growth and development.

Example: Damage to the occipital lobe can result in visual impairment.

Neural Communication

Neurons communicate through electrical and chemical signals, enabling complex behaviors and mental processes.

• Action Potential: A brief electrical charge that travels down the axon of a neuron, enabling signal transmission.

• Depolarization: The process during which the neuron's membrane potential becomes less negative, leading to the firing of an action potential.

• Refractory Period: A short period after an action potential during which a neuron cannot fire again.

• Synaptic Gap (Synapse): The small space between neurons where neurotransmitters are released to transmit signals.

• Neurotransmitters (NTs): Chemical messengers that cross synapses to transmit signals between neurons. Examples include dopamine, endorphins, and others.

• Dopamine: Involved in reward, motivation, and motor control.

• Endorphins: Natural painkillers produced by the brain.

Example: Dopamine release is associated with pleasurable activities and is implicated in addiction.

Drugs and the Brain

Psychoactive drugs alter brain function, affecting mood, perception, and behavior.

• Barbiturates: Depress the activity of the central nervous system, reducing anxiety but impairing memory and judgment.

• Marijuana, Cocaine, Heroin: Each affects the brain differently, often by altering neurotransmitter activity.

• Tolerance: The need for increasing amounts of a drug to achieve the same effect.

• Relation between Alcohol and Disorders: Chronic alcohol use can lead to substance use disorders and impact brain function.

Example: Cocaine increases dopamine levels, leading to intense euphoria followed by a crash.

Consciousness and Sleep

Consciousness

Consciousness refers to our awareness of ourselves and our environment.

• Conscious: Being aware of and able to respond to one's surroundings.

• Unconscious: Mental processes that occur without conscious awareness.

• Textbook Definition: Consciousness is the subjective awareness of internal and external events.

Example: Daydreaming is a form of altered consciousness.

Sleep and Sleep Stages

Sleep is a natural, periodic state of rest for the mind and body, divided into several stages.

• REM Sleep (Rapid Eye Movement): A sleep stage characterized by rapid eye movements, vivid dreams, and increased brain activity. Most dreaming occurs during REM sleep.

• NREM Sleep (Non-REM): Encompasses all sleep stages except REM. NREM sleep is divided into stages, including deep sleep.

• Alpha Waves: Brain waves that indicate a relaxed, awake state.

• Delta Waves: Slow brain waves associated with deep NREM sleep.

• Sequential Processing: The processing of one aspect of a problem at a time; generally used to process new information or solve difficult problems.

• Information Processing: The brain's method of encoding, storing, and retrieving information, often linked to the function of sleep and dreams.

Example: During REM sleep, the brain is highly active, and most vivid dreams occur.

Sleep Disorders

Various disorders can disrupt normal sleep patterns, affecting health and daily functioning.

• Insomnia: Difficulty falling or staying asleep.

• Sleep Apnea: A disorder in which breathing repeatedly stops and starts during sleep.

• Narcolepsy: A chronic sleep disorder characterized by overwhelming daytime drowsiness and sudden attacks of sleep.

• Nightmares: Frightening dreams that occur during REM sleep; may have adaptive or psychological benefits.

• Benefit of Nightmares: May help process emotions or rehearse responses to threats.

Example: People with sleep apnea may stop breathing hundreds of times per night, leading to poor sleep quality.

Dreams

Dreams are sequences of images, emotions, and thoughts passing through a sleeping person's mind, most commonly during REM sleep.

• REM Dreams: Typically more vivid, emotional, and story-like than NREM dreams.

• Functions of Dreams: Theories suggest dreams help with memory consolidation, emotional regulation, and problem-solving.

Example: A person may dream about a stressful event as a way of processing emotions related to it.

Effects of Sleep Deprivation and Distraction

Lack of sleep and distractions (such as using a cellphone while driving) can impair cognitive and physical performance.

• Driving with Cellphone Impact: Increases risk of accidents due to divided attention and slower reaction times.

• Free Radicals: Molecules that can damage cells; sleep may help clear free radicals from the brain.

Example: Sleep deprivation can lead to impaired memory, mood disturbances, and decreased immune function.

Table: Comparison of Sleep Stages

Key Terms and Definitions

• Action Potential:

• Depolarization:

• Refractory Period:

• Synaptic Gap:

• Neurotransmitter:

• Tolerance: