Limbic system HHAC: Hippocampus, Hypothalamus, Amygdala, Cingulate
Limbic System
Four key structures that govern emotion and memory
Hippocampus: memory formation. Hypothalamus: hunger, thirst, temperature, hormones. Amygdala: fear and emotion. Cingulate cortex: attention and error detection.
H
Hippocampus — memory
H
Hypothalamus — homeostasis
A
Amygdala — fear/emotion
C
Cingulate — attention
Neuron Structure and Function
Neurons: dendrites receive, cell body integrates, axon transmits, synapse releases
Neuron Structure and Function
The basic unit of the nervous system — how a signal travels
Dendrites: receive signals from other neurons. Cell body (soma): integrates signals. Axon: transmits signal to terminals. Synapse: junction where neurotransmitters are released to the next neuron. All-or-nothing firing principle.
Five neurotransmitters every psychology student must know
Serotonin: mood, sleep, appetite — low levels linked to depression. SSRIs block reuptake, increasing serotonin. Dopamine: reward, motivation, movement — excess linked to schizophrenia, deficiency to Parkinson's. Norepinephrine: arousal, fight-or-flight. GABA: main inhibitory NT — alcohol and benzodiazepines enhance it. Glutamate: main excitatory NT.
How neurons fire — the all-or-nothing electrical signal
Resting: -70mV inside relative to outside (Na⁺ out, K⁺ in). Threshold: stimulus sufficient → Na⁺ rushes in → depolarization. Propagates down axon. Repolarization: K⁺ rushes out. Refractory period: brief inability to fire again. All-or-nothing: either fires fully or not at all — no partial signals.
Neuroplasticity
Neuroplasticity: brain reorganizes itself. Hebbian learning: neurons that fire together wire together.
Neuroplasticity
The brain's ability to change and reorganize throughout life
The brain is not static — it changes with experience. Hebbian learning: repeated activation of two neurons together strengthens their connection. London taxi drivers: enlarged hippocampus from spatial navigation demands. Stroke recovery: neighboring areas take over functions of damaged areas. Learning builds new synaptic connections.
Brain Lateralization
Hemispheric specialization: left (language, logic, detail). Right (spatial, holistic, creativity). Connected by corpus callosum.
Brain Lateralization
How the two hemispheres divide their functions
Left hemisphere: language (in most people), analytical thinking, detail processing, sequential. Right hemisphere: spatial processing, holistic thinking, face recognition, emotion processing. Contralateral control: left brain controls right side of body and vice versa. Corpus callosum: the bridge connecting hemispheres — severed in split-brain patients.
Endocrine System and Behavior
Endocrine system: hormones travel through blood. Slower than nervous system but longer-lasting effects.
Endocrine System and Behavior
How hormones influence psychology and behavior
Pituitary gland: 'master gland' — regulates other glands. Adrenal glands: cortisol (stress, immune suppression), adrenaline (fight-or-flight). Thyroid: metabolism and energy. Gonads: estrogen and testosterone — sexual development, mood, aggression. Pineal gland: melatonin — sleep-wake cycles.
Sleep Stages
Sleep stages: NREM 1-3 (light to deep sleep) → REM (dreaming, memory consolidation). Cycle repeats ~90 min.
The sequence of events in neural firing — from resting state to action potential
Action potentials are all-or-none — the neuron either fires completely or not at all
Resting potential: -70mV — Na+ out, K+ in (sodium-potassium pump). Threshold: -55mV. Depolarization: Na+ rushes in → membrane reaches +40mV. Repolarization: K+ rushes out → returns to resting. Refractory period: absolute (cannot fire again), then relative (needs stronger stimulus). Action potential travels down axon → triggers vesicle release → neurotransmitters cross synapse → bind receptors. Myelin sheath speeds conduction (saltatory conduction).
All-or-none
Neuron fires completely or not at all — no partial firing
Myelin
Speeds conduction — MS = myelin destruction
Synapse
NTs released into gap → bind postsynaptic receptors
Hemispheric Specialization
LEFT = Language, Logic · RIGHT = Spatial, Creative
Lateralization of function between the left and right cerebral hemispheres
The two hemispheres specialize — split-brain research by Sperry and Gazzaniga proved it
Left hemisphere: language production and comprehension (in 95% of right-handers), analytical thinking, sequential processing, verbal memory. Right hemisphere: spatial processing, face recognition, holistic processing, emotional tone of speech (prosody), creative thinking. Corpus callosum: connects the hemispheres. Split-brain patients (corpus callosum severed): left hand "doesn't know" what right hand is doing — objects presented to left visual field (right hemisphere) cannot be named.
Left
Language, logic, sequential — dominant in most people
Right
Spatial, faces, holistic — prosody and creativity
Split-brain
Sperry and Gazzaniga — cutting corpus callosum separates hemispheres
🎓 Common Exam Questions
Q: Describe the steps of neural transmission from action potential to postsynaptic effect.
A: Resting potential: neuron at -70mV — maintained by Na+/K+ ATPase pump (3 Na+ out, 2 K+ in) and selective permeability. Stimulus reaches threshold (-55mV) → voltage-gated Na+ channels open → Na+ floods in → depolarization to +40mV → action potential. Repolarization: Na+ channels close, K+ channels open → K+ flows out → returns to resting. Absolute refractory period: cannot fire again (Na+ channels inactivated). Action potential travels down axon (myelinated = saltatory conduction, faster). At axon terminal: Ca2+ influx triggers vesicle fusion → neurotransmitters released into synaptic cleft → bind postsynaptic receptors → excitatory (EPSP) or inhibitory (IPSP) postsynaptic potential. NT is then reuptaken, degraded, or diffuses away.
Q: What are the major lobes of the cerebral cortex and their primary functions?
A: Frontal lobe: motor cortex (voluntary movement), prefrontal cortex (executive function, planning, impulse control, personality), Broca's area (left hemisphere — speech production). Damage to PFC: personality change (Phineas Gage), impaired decision-making, loss of inhibition. Parietal lobe: somatosensory cortex (touch, proprioception), spatial processing, integration of sensory information. Temporal lobe: auditory cortex (hearing), Wernicke's area (left hemisphere — language comprehension), hippocampus and amygdala (deep), face recognition (right). Occipital lobe: primary visual cortex — destruction causes cortical blindness. Key principle: contralateral control — left hemisphere controls right side of body and vice versa.
Q: What is neuroplasticity and what are its implications for psychology?
A: Neuroplasticity: the brain's ability to change structure and function in response to experience throughout the lifespan. Mechanisms: synaptic strengthening (LTP — Long-Term Potentiation via NMDA receptors, Hebb's rule: neurons that fire together wire together), pruning (elimination of unused synapses — peaks in childhood and adolescence), neurogenesis (new neurons in hippocampus — promoted by exercise, stress-impaired). Implications: early experience shapes brain development profoundly — critical periods for language, vision, attachment. Recovery from brain injury possible through rehabilitation — undamaged areas take over function. Exercise promotes BDNF (brain-derived neurotrophic factor) and hippocampal neurogenesis. Depression associated with hippocampal shrinkage — antidepressants promote neurogenesis.
Q: How does the endocrine system interact with the brain to influence behavior?
Q: Compare the sympathetic and parasympathetic divisions of the autonomic nervous system.
A: Sympathetic nervous system: 'fight or flight' — thoracolumbar (T1-L2). Increases heart rate, dilates pupils, diverts blood to muscles, inhibits digestion, stimulates epinephrine/norepinephrine release from adrenal medulla. Preganglionic: acetylcholine. Postganglionic: norepinephrine (most organs) or acetylcholine (sweat glands). Parasympathetic nervous system: 'rest and digest' — craniosacral (cranial nerves III, VII, IX, X + S2-S4). Decreases heart rate (vagus nerve), stimulates digestion, promotes sexual arousal, constricts pupils. Preganglionic and postganglionic: both acetylcholine. Enteric nervous system: 'second brain' — 100 million neurons in gut wall, operates independently. ANS controlled by hypothalamus. Biofeedback can train voluntary control of some ANS responses.