chapter 1: biology and behavior

Classic debate about relative contributions of genetics (nature) and environment (nurture) to traits; most traits involve both

Nature vs. nurture

Compares trait frequency within a family to general population

Family studies

Compares concordance rates between monozygotic (identical) and dizygotic (fraternal) twins

Twin studies

Compares similarities between adopted children and adoptive parents versus biological parents

Adoption studies

Nervous system develops through neurulation; notochord stimulates ectoderm to fold over, creating neural tube topped with neural crest cells

Neurulation

Becomes the central nervous system

Neural tube

Spread throughout body, differentiating into many tissues

Neural crest cells

Primitive reflexes exist in infants and disappear with age; protective role; can reappear in nervous system disorders

Primitive reflexes

Infant turns head toward anything brushing cheek

Rooting reflex

Infant extends arms, then retracts and cries in response to falling sensation

Moro reflex

Big toe extends and other toes fan in response to brushing sole of foot

Babinski reflex

Infant grasps anything placed in hand

Grasping reflex

Skills and abilities expected at a given age; most children adhere closely to these

Developmental milestones

Gross and fine motor abilities progress head-to-toe and core-to-periphery

Motor development pattern

Social skills shift from parent-oriented to self-oriented to other-oriented

Social development pattern

Language skills become increasingly complex

Language development pattern

Controls fear and aggression

Amygdala

Consolidates memories and communicates with limbic system via fornix

Hippocampus

Divided into frontal, parietal, occipital, and temporal lobes

Cerebral cortex

Controls executive function, impulse control, planning, motor function, speech production

Frontal lobe

Controls touch, pressure, temperature, pain; spatial processing and orientation

Parietal lobe

Controls visual processing

Occipital lobe

Controls sound processing, speech perception, memory, emotion

Temporal lobe

Left hemisphere usually dominant for language

Cerebral hemispheres

Released by neurons; carry signal to another neuron or effector

Neurotransmitters

Used by somatic nervous system (muscle movement), parasympathetic system, and CNS (alertness)

Acetylcholine

Maintains smooth movements and steady posture

Dopamine

Natural painkillers

Endorphins and enkephalins

Maintain wakefulness and alertness; mediate fight-or-flight; epinephrine acts as hormone, norepinephrine as neurotransmitter

Epinephrine and norepinephrine

Brain stabilizers

GABA and glycine

Excitatory neurotransmitter in brain

Glutamate

Modulates mood, sleep, eating, and dreaming

Serotonin

Stress hormone released by adrenal cortex

Cortisol

Mediates libido; testosterone also increases aggression; released by adrenal cortex and gonads

Testosterone and estrogen

Released by adrenal medulla; cause physiological changes of sympathetic nervous system

Epinephrine and norepinephrine (adrenal medulla)

Study of connection between nervous system and behavior; focuses on brain region functions

Neuropsychology

Three types of neurons: sensory (afferent), motor (efferent), interneurons

Neuron types

Ability of interneurons in spinal cord to relay info to source of stimulus while routing to brain

Reflex arcs

Made up of CNS (brain and spinal cord) and PNS (cranial and spinal nerves)

Nervous system organization

PNS divided into somatic (voluntary) and autonomic (automatic) divisions

Peripheral nervous system divisions

Autonomic system divided into parasympathetic (rest-and-digest) and sympathetic (fight-or-flight) branches

Autonomic nervous system divisions

Brain subdivisions: hindbrain, midbrain, forebrain

Brain organization

Contains cerebellum, medulla oblongata, reticular formation

Hindbrain

Contains inferior and superior colliculi

Midbrain

Contains thalamus, hypothalamus, basal ganglia, limbic system, cerebral cortex

Forebrain

Relay station for sensory information

Thalamus

Maintains homeostasis; integrates with endocrine system via hypophyseal portal to anterior pituitary

Hypothalamus

Smoothens movements and maintains postural stability

Basal ganglia

Controls emotion and memory; includes septal nuclei, amygdala, hippocampus

Limbic system

Involved with pleasure, pleasure-seeking, and addiction

Septal nuclei

Methods of studying brain: lesions, electrical stimulation, EEG, regional cerebral blood flow

Brain study methods