Brain Atlas
Major regions first, interlinked circuits second
Start with specialization: what each major brain region is best known for when examined on its own.
Case Mode
Practice consult-level localization before the reveal
Treat each vignette like senior consult rounds: formulate the syndrome, rank the localization hierarchy, name the most decisive next data, and then compare your working localization against the strongest network-level target.
Training stage
Post-clinical localization
Post-clinical objectives
- • Separate cortical, subcortical, cerebellar, and brainstem patterns before naming a disease.
- • Reject weaker competing localizations using exam asymmetry, cortical signs, and network logic.
Clinical vignette
Planning failure after frontal injury
A patient can speak and move but cannot organize multi-step tasks or suppress impulsive responses.
Chief complaint
Family reports severe disorganization and poor judgment after a head injury.
History
The patient forgets goals halfway through tasks, perseverates on the wrong rule, and becomes impulsive when asked to switch plans.
Syndrome frame
A frontal executive syndrome with impaired set maintenance, inhibitory control, and behavioral regulation, but without a primary aphasic, pyramidal, or cerebellar pattern.
Exam findings
- • Poor set shifting on executive testing
- • Marked distractibility with intact primary strength and sensation
- • Behavioral disinhibition without aphasia or cerebellar ataxia
Prompt
Which region is the best localization target for this syndrome, and why does that region fit better than a purely motor or sensory explanation?
Localization cues
- • The dominant deficit is failure of task set maintenance and inhibition.
- • Primary cortical outputs are largely preserved, so the problem lies upstream of execution.
Differential traps
- • Do not mislabel slowed or chaotic behavior as primary motor weakness.
- • Poor recall during distracted testing can be secondary to executive failure rather than pure hippocampal amnesia.
Next data to request
- • Formal set-shifting or Stroop-style testing to show impaired top-down control.
- • A careful language screen to exclude aphasia masquerading as disorganization.
Current pick: Prefrontal Cortex
Functional map
Regional specialization
Prefrontal Cortex
Keeps goals online, suppresses distractions, and lets you plan beyond the present moment.
Core functions
- • Executive control
- • Working memory
- • Decision-making
- • Inhibitory control
Signature tasks
- • Rule switching
- • Delayed-response tasks
- • Planning multi-step behavior
Clinical link
Damage produces dysexecutive syndrome: poor planning, impulsivity, and difficulty maintaining goals.
How to read Chapter 1
Principle 1
Most brain communication is recurrent rather than one-way: cortex sends down, subcortex sends back, and both reshape each other.
Principle 2
Hub regions such as the thalamus and prefrontal cortex matter because they coordinate timing and routing, not because they work alone.
Principle 3
Clinical syndromes often reflect broken loops rather than isolated damage to a single named structure.