3.2 Neuroanatomy, Neurotransmission, and Imaging

Brain systems, signals, and evidence limits

Neuroanatomy on the EPPP is best studied as functional networks tied to lesion signs. The frontal lobes support planning, response inhibition, working memory, and social judgment; the prefrontal cortex underlies executive control, and damage can cause disinhibition or personality change (the classic Phineas Gage pattern). Temporal systems support auditory processing, language comprehension (Wernicke's area), and, via the hippocampus, the formation of new declarative memories. Parietal cortex handles spatial attention and sensory integration; right-parietal lesions can produce contralateral neglect.

Occipital cortex handles vision.

The limbic system is not one emotion button. The amygdala tags salience and threat and drives fear learning; the hippocampus binds context and forms episodic memories; the hypothalamus links neural activity to autonomic and endocrine control; the basal ganglia support movement initiation, habit, and reward (degeneration appears in Parkinson and Huntington disease); the cerebellum coordinates movement and contributes to cognition and affect. Broca's area (left frontal) governs speech production, so a non-fluent, effortful speech pattern points there.

Neurotransmitter systems

Learn transmitters as broad systems. Dopamine supports reward, salience, and movement; excess mesolimbic activity is central to the dopamine hypothesis of psychosis, and depletion underlies Parkinsonian symptoms. Serotonin (5-HT) modulates mood, anxiety, sleep, appetite, and impulse control. Norepinephrine drives arousal and vigilance. Acetylcholine supports memory and neuromuscular signaling; cholinergic loss is prominent in Alzheimer disease.

Gamma-aminobutyric acid (GABA) is the main inhibitory transmitter (benzodiazepines act here), and glutamate is the main excitatory transmitter, central to learning and synaptic plasticity (long-term potentiation).

Psychophysiology and stress

The autonomic nervous system divides into the sympathetic branch (fight-or-flight, increased heart rate, pupil dilation) and the parasympathetic branch (rest, digest, recovery). The hypothalamic-pituitary-adrenal (HPA) axis links stress appraisal to cortisol release; chronic activation can disrupt sleep, attention, mood, and immune function.

Imaging methods and their limits

All of these are correlational unless the design supports more. fMRI does not show thoughts; it tracks blood-oxygen change downstream of activity.

Scenario pattern. Sudden language difficulty plus right-sided weakness signals possible stroke; the safe answer is urgent medical evaluation, not psychotherapy interpretation. Scenario pattern. Chronic inattention with heavy stimulant use and sleep loss demands a multi-cause differential before any single diagnosis.

Common study mistakes:

• Memorizing a structure without its functional signs.
• Treating fMRI/PET as a direct readout of intentions.
• Skipping medical referral when signs are sudden, severe, progressive, or focal.
• Forgetting plasticity: brain systems change with learning, development, and treatment.

Lateralization, plasticity, and aphasia patterns

The EPPP frequently contrasts left- and right-hemisphere functions. In most people the left hemisphere is dominant for language and sequential analysis, while the right hemisphere specializes in visuospatial processing, prosody, and global pattern recognition. Damage to Broca's area (left inferior frontal) yields non-fluent, effortful, telegraphic speech with relatively preserved comprehension, whereas Wernicke's area (left posterior temporal) damage produces fluent but meaningless speech with impaired comprehension. A disconnection between the two can cause conduction aphasia (impaired repetition).

Right-hemisphere damage more often produces neglect and impaired social-emotional reading.

Neuroplasticity means the brain reorganizes with experience, learning, and recovery; this underlies rehabilitation and explains why behavioral interventions can change neural function. Developmental plasticity is greatest early in life, but adult brains retain meaningful capacity for change.

Putting it together in a referral decision

When a stem describes cognitive or behavioral change, run a rapid differential: Is the onset sudden (vascular, traumatic) or gradual (neurodegenerative)? Are signs focal (one limb, one language function) or diffuse (global confusion, fluctuating attention suggesting delirium)? Is there a reversible contributor — medication, substance, infection, metabolic or endocrine disturbance, sleep loss? Delirium is acute, fluctuating, and often reversible; dementia is gradual and progressive. Mistaking one for the other is a frequent distractor.

For licensure-level reasoning, explain behavior through converging evidence: history, observation, test data, medical information, collateral reports, and functional impairment outweigh a single attractive neuroscience phrase. When in doubt, the safe answer assesses broadly, protects safety, and refers for medical evaluation when neurological risk is plausible.

One more high-yield contrast: the central nervous system (brain and spinal cord) versus the peripheral nervous system (somatic and autonomic divisions). Reflex arcs travel through the spinal cord without cortical involvement, which is why some responses occur before conscious awareness. The myelin sheath speeds neural conduction, and demyelinating disease (such as multiple sclerosis) slows it, producing varied sensory and motor signs.

Knowing this architecture helps a candidate distinguish a plausible neurological explanation from a distractor that misattributes a peripheral symptom to a cortical cause, and reinforces why focal, progressive, or fluctuating signs warrant medical work-up rather than routine psychotherapy framing.