📖 In-Depth Theory
Structure of the Brain
The BRAIN is the most complex organ in the human body — containing approximately 86 billion neurones, each connected to thousands of others.
The brain has several distinct regions, each responsible for different functions:
CEREBRAL CORTEX (cerebrum):
The largest part of the brain — the highly folded outer layer.
Responsible for: consciousness, intelligence, memory, language, personality, voluntary movement, sensory perception.
Divided into left and right hemispheres — each processes information from the opposite side of the body.
The folded structure (gyri and sulci) increases surface area for more neurones.
CEREBELLUM:
Located at the back and base of the brain.
Responsible for: coordination of movement, balance, posture, fine motor control.
Damage → loss of coordination and balance.
MEDULLA OBLONGATA:
At the base of the brain, continuous with the spinal cord.
Controls: unconscious vital functions — heart rate, breathing rate, blood pressure, swallowing, vomiting.
Damage is life-threatening — these functions are essential for survival.
How We Study the Brain
The brain is extremely complex and difficult to study — it cannot easily be biopsied or experimented on safely.
METHODS:
ELECTROENCEPHALOGRAPHY (EEG):
Electrodes placed on the scalp record electrical activity of the brain as patterns of waves.
Used to diagnose epilepsy and sleep disorders.
Shows which areas are active but with limited spatial resolution.
FUNCTIONAL MRI (fMRI):
Detects changes in blood flow to different brain regions — more active regions need more blood and oxygen.
Produces detailed 3D images showing which brain regions are active during different tasks.
Allows mapping of brain function non-invasively.
Used in research to understand language, memory, emotion and decision-making.
ELECTRICAL STIMULATION:
Neurosurgeons can stimulate specific brain regions electrically during brain surgery (patient kept awake).
The patient reports what they experience — helping identify which areas control which functions.
Led to early mapping of sensory and motor areas.
STUDYING BRAIN DAMAGE:
Case studies of patients with specific brain injuries have provided crucial insights.
Famous case: Phineas Gage — a railway worker whose personality changed dramatically after a rod passed through his frontal lobe (1848).
Patient HM — removal of hippocampus to treat epilepsy caused inability to form new long-term memories.
Why the Brain is Difficult to Treat
Treating brain conditions is extremely challenging:
BLOOD-BRAIN BARRIER:
A layer of tightly packed cells around brain blood vessels that prevents many substances from crossing from blood into brain tissue.
Protects the brain from pathogens and toxins — but also prevents many drugs from reaching brain tissue.
Drug delivery to the brain is a major challenge in neurology and psychiatry.
NEURONE REPAIR:
Unlike most body tissues, adult brain neurones cannot regenerate if damaged.
This is why brain injuries (stroke, trauma) often cause permanent deficits.
Stem cell research aims to find ways to regenerate damaged brain tissue.
ETHICAL CONSTRAINTS:
Brain tissue cannot be biopsied safely — unlike a tumour elsewhere.
Experimentation is limited by the ethical requirement to protect patients.
Much of our knowledge comes from accidents, disease and animal studies.
⚠️ Common Mistake
Students often mix up the three main brain regions. CEREBRAL CORTEX = thinking, memory, language, voluntary movement. CEREBELLUM = coordination and balance. MEDULLA = heart rate and breathing (vital automatic functions). A useful memory trick: 'Cerebellum = coordination' (both start with C and 'coordination').