Biological Basis of Behavior: Genetics, Neuroscience, and Psychopharmacology

What is the core concept of the nature vs. nurture dialectic?

Human development, behavior, and cognitive functioning result from interactions between genetic inheritance (nature) and experiential context (nurture).

What does heredity refer to in the context of behavior?

Heredity refers to the genetic or biological predispositions passed down from biological parents to offspring, encoded within DNA.

How does the environment influence behavior?

The environment encompasses external influences, ecological contexts, and experiential variables encountered throughout life, such as family dynamics and socioeconomic status.

What is the fallacy of exclusivity in the nature vs. nurture debate?

Genetic architecture and environmental circumstances are not mutually exclusive; they constantly modulate each other.

What are gene-environment interactions?

Gene-environment interactions occur when an individual's genetic predispositions influence the environments they select or evoke.

What is the theoretical foundation of the evolutionary perspective?

It is based on principles of evolutionary biology, analyzing psychological traits and behaviors as adaptations for survival and reproductive success.

What is natural selection?

Natural selection is the process by which heritable traits that confer survival or reproductive advantages are preserved and passed on.

What are genetic mutations?

Genetic mutations are random alterations in DNA sequences that can introduce beneficial variations for natural selection.

How do innate fears relate to evolutionary psychology?

Innate fears, like ophidiophobia, reflect evolutionary conditioning that enhanced survival rates of ancestors who could quickly detect threats.

What does Robert Sapolsky's framework suggest about human behavior?

Sapolsky highlights that human behavior is influenced by both genetic predispositions and environmental factors.

What is behavior genetics?

Behavior genetics is the field that investigates the contributions of genetic and environmental variation to psychological and physiological differences.

What are monozygotic twins?

Monozygotic twins are identical twins that originate from a single fertilized ovum, sharing 100% of their genetic code.

How do dizygotic twins differ from monozygotic twins?

Dizygotic twins develop from two separate ova fertilized by distinct sperm, sharing approximately 50% of their genes.

What is the purpose of adoption studies in behavior genetics?

Adoption studies compare adopted children to their biological and adoptive parents to assess genetic versus environmental influences on traits.

What are epigenetic mechanisms?

Epigenetic mechanisms involve changes in gene expression that do not alter the DNA sequence, often influenced by environmental factors.

What does the maternal licking paradigm demonstrate?

It shows that maternal care in rodents can induce epigenetic modifications affecting stress and anxiety responses in offspring.

What is eugenics?

Eugenics is a movement that sought to apply selective breeding to human populations to direct genetic evolution.

What are the ideological flaws of eugenics?

Eugenics oversimplified complex human traits as Mendelian, ignoring the role of environment and polygenic inheritance.

What historical consequences did the American eugenics movement have?

It led to the forced sterilization of over 60,000 individuals based on racial and class prejudices.

What is the biological primacy in psychology?

It asserts that all cognitive, emotional, and behavioral phenomena originate within physiological systems.

What is the primary function of the central nervous system (CNS)?

The CNS acts as the executive decision-maker, integrating sensory data and coordinating physiological responses.

What anatomical components make up the CNS?

The CNS consists of the brain and spinal cord, encased within protective bone and meninges.

What is the primary function of the spinal cord?

It serves as a conduit for bidirectional neural traffic between the brain and the peripheral nervous system.

What is a reflex?

An involuntary, immediate, automatic motor response to sensory stimulation that bypasses initial processing in the cerebral cortex.

What is the role of the sensory receptor in the reflex arc?

It detects intense or noxious physical stimuli.

What does the afferent (sensory) neuron do?

It transmits the generated action potential from the peripheral receptor to the dorsal horn of the spinal cord.

What is the function of the interneuron in the reflex arc?

It rapidly routes the neural impulse to an efferent motor neuron and transmits collateral signals to the brain.

What is the role of the efferent (motor) neuron?

It propagates the motor command outward to the periphery.

What is an effector in the context of a reflex arc?

The target muscular tissue that contracts in response to a motor command.

What does the Peripheral Nervous System (PNS) encompass?

All neural structures outside the cranial vault and vertebral column, including cranial and spinal nerves.

What are the two functional subdivisions of the PNS?

The Somatic Nervous System and the Autonomic Nervous System.

What is the primary role of the Somatic Nervous System (SNS)?

To mediate voluntary sensorimotor activities.

What does the Autonomic Nervous System (ANS) regulate?

Involuntary visceral mechanisms that sustain life and maintain internal homeostasis.

What is the activation mechanism of the Sympathetic Nervous System?

It engages during physical exertion or acute threats, coordinating energy mobilization.

What physiological changes occur during sympathetic activation?

Pupillary dilation, increased heart rate, bronchodilation, and inhibition of digestive processes.

What is the function of the Parasympathetic Nervous System?

To promote energy conservation and tissue recovery during non-threatening conditions.

What physiological changes occur during parasympathetic activation?

Pupil constriction, decreased heart rate, increased gastrointestinal activity, and muscle relaxation.

What are the primary functional units of neural computation?

Neurons.

What are glial cells (neuroglia)?

Non-conducting cellular units that provide support, protection, and homeostatic regulation for neurons.

What is the role of astrocytes in the CNS?

They regulate extracellular ion homeostasis and maintain the blood-brain barrier.

What do oligodendrocytes do?

They form the myelin sheath around central nervous system axons.

What is the function of Schwann cells?

They form the myelin sheath around peripheral nerve axons.

What is the role of microglia?

They act as resident macrophages that clear debris and coordinate neuroinflammatory responses.

What is the function of ependymal cells?

They line the cerebral ventricles and central canal, synthesizing and circulating cerebrospinal fluid (CSF).

What is the cell body (soma) of a neuron?

The metabolic core containing the nucleus, mitochondria, and organelles necessary for cellular maintenance.

What is the role of dendrites in a neuron?

They gather chemical signals from other neurons.

What is the axon hillock?

The transition zone between the soma and axon that integrates excitatory and inhibitory signals.

What is the myelin sheath?

An insulating layer that reduces membrane capacitance and prevents ionic leakage along the axon.

What are nodes of Ranvier?

Unmyelinated gaps along the axon that facilitate saltatory conduction.

What are the three functional classifications of neurons?

Sensory (afferent), motor (efferent), and interneurons.

What is the resting membrane potential of a neuron?

Approximately -70 mV, maintained by differential ionic distributions.

What maintains the negative charge inside a neuron?

Differential ionic distributions: high potassium ions (K+) and organic anions inside, contrasted with high sodium ions (Na+) and chloride ions (Cl-) outside.

What triggers an action potential in a neuron?

Graded depolarization to a critical voltage, typically around -55 mV.

What happens during depolarization?

Voltage-gated sodium channels open, allowing Na+ ions to rush into the cell, inverting the membrane potential to around +30 to +40 mV.

What is the All-or-Nothing Principle in action potentials?

An action potential fires at uniform velocity and amplitude if the threshold is reached; if not, it does not fire.

What occurs during repolarization?

Voltage-gated Na+ channels inactivate and K+ channels open, allowing K+ ions to exit the cell, restoring a negative internal charge.

What is hyperpolarization?

A temporary state where the membrane potential is driven below the resting potential, e.g., -80 mV, due to excess K+ efflux.

What is the Absolute Refractory Period?

The phase when voltage-gated Na+ channels are inactivated, preventing the neuron from firing another action potential.

What is the Relative Refractory Period?

The interval after the absolute refractory period where a stronger-than-normal stimulus is required to generate an action potential.

What is a synapse?

The functional junction across which neural communication occurs, consisting of the presynaptic membrane, synaptic cleft, and postsynaptic membrane.

What triggers exocytosis in synaptic transmission?

The influx of Ca2+ ions into the presynaptic terminal due to action potential depolarization.

How do neurotransmitters bind in synaptic transmission?

Ligands diffuse across the synaptic cleft and bind to specific receptor proteins on the postsynaptic membrane.

What are the methods of signal termination in synaptic transmission?

Enzymatic degradation, passive diffusion away from the cleft, or reuptake into the presynaptic terminal.

What is Multiple Sclerosis (MS)?

A progressive autoimmune disorder that destroys the myelin sheath of CNS axons, leading to muscle weakness and sensory deficits.

What characterizes Myasthenia Gravis?

An autoimmune disorder where antibodies block ACh receptors at the neuromuscular junction, causing fluctuating muscle weakness.

What are excitatory neurotransmitters?

Neurotransmitters that induce depolarization of the postsynaptic membrane, increasing the likelihood of action potential generation.

What are inhibitory neurotransmitters?

Neurotransmitters that promote hyperpolarization of the postsynaptic membrane, decreasing the likelihood of action potential generation.

What role does dopamine (DA) play in the brain?

It regulates reward anticipation, motivation, reinforcement learning, and voluntary motor control; implicated in schizophrenia and Parkinson's disease.

What is the function of norepinephrine (NE)?

It drives alertness, arousal, and the fight-or-flight response; synthesized in the locus coeruleus.

What is glutamate's role in the brain?

It is the principal excitatory neurotransmitter involved in cognitive functioning and long-term potentiation (LTP).

What is Substance P?

A neuropeptide neurotransmitter that conveys pain signals and induces neurogenic inflammation; linked to chronic pain syndromes.

What is the function of GABA?

The primary inhibitory neurotransmitter that hyperpolarizes the postsynaptic membrane, reducing neural excitability.

What does serotonin (5-HT) regulate?

Emotional stability, mood, sleep architecture, appetite, and pain perception; dysregulation is linked to depression and anxiety.

What are endorphins?

Endogenous opioids released during stress or pain that inhibit pain perception and promote feelings of pleasure.

What is the role of acetylcholine (ACh) at the neuromuscular junction?

It drives skeletal muscle contractions and is crucial for attention and memory in the CNS.

How does the endocrine system communicate?

Through chemical messengers called hormones released into the bloodstream, contrasting with the rapid impulses of the nervous system.

What is the primary function of the endocrine system?

To operate via chemical messengers called hormones released into the bloodstream for systemic communication.

What is the role of the pituitary gland?

Known as the 'master gland,' it secretes trophic hormones that regulate the activity of peripheral endocrine glands.

What hormone does the pineal gland secrete?

Melatonin, which regulates circadian rhythms and the sleep-wake cycle.

What are the two main parts of the adrenal glands?

The outer cortex, which secretes glucocorticoids like cortisol, and the inner medulla, which secretes adrenaline and noradrenaline.

What is the function of leptin?

A hormone that suppresses hunger and stimulates metabolic expenditure, reflecting systemic adipose reserves.

What is ghrelin and its role?

A peptide hormone that stimulates appetite and gastrointestinal motility, secreted during fasting states.

What does oxytocin do?

Stimulates uterine contractions during childbirth and milk ejection during lactation, also fostering social bonding.

Define psychoactive drugs.

Chemical substances that alter neuronal transmission, affecting perception, emotion, consciousness, and behavior.

What are agonists in the context of drug action?

Molecules that mimic neurotransmitters by activating postsynaptic receptors and triggering physiological responses.

What is the function of antagonists?

Molecules that block receptor activation by binding to receptors without triggering an intracellular response.

What do reuptake inhibitors do?

Prevent the re-absorption of neurotransmitters, prolonging their action in the synaptic cleft.

What are stimulants?

Drugs that accelerate central nervous system activity, increasing heart rate and vigilance.

How does caffeine affect the central nervous system?

It antagonizes adenosine receptors, increasing dopamine and norepinephrine release, enhancing alertness.

What is cocaine's mechanism of action?

It blocks dopamine, norepinephrine, and serotonin transporters, leading to increased dopamine levels and euphoria.

Describe the effects of amphetamines.

They promote neurotransmitter release and reverse transporter proteins, flooding synapses with dopamine and norepinephrine.

What is methamphetamine and its effects?

A potent stimulant that rapidly increases dopamine levels, causing prolonged energy and severe health risks.

What is ecstasy (MDMA) known for?

It triggers massive serotonin release, leading to emotional empathy and sensory distortions.

What are depressants?

Drugs that inhibit CNS activity, reducing neural firing rates and slowing respiration and heart rate.

How does alcohol affect the brain?

It enhances GABA's inhibitory effects and depresses cortical judgment centers, impairing motor coordination.

What are barbiturates and their effects?

Addictive sedative-hypnotics that enhance GABA action, reducing anxiety and inducing anesthesia at high doses.

What are benzodiazepines used for?

Common anti-anxiety medications that increase GABA receptor activity with lower overdose risk than barbiturates.

What are opioids and their effect on the CNS?

Analgesics that depress CNS functioning by binding to mu-opioid receptors, inhibiting pain processing.

What initiated Wave 1 of the opioid epidemic?

The late 1990s over-prescription of therapeutic opioids.

What characterized Wave 2 of the opioid epidemic?

A rise in overdose fatalities linked to illicit heroin as prescription opioids became regulated.