Early brain structures
The BRAIN magazine
The neural tube is initially straight with little semblance of the functionally distinct areas of the adult human brain. However, even before the neural tube is fully closed, its front part elongates and bends, forming three distinct developmental structures known as primary brain vesicles: the forebrain, the midbrain, and the hindbrain.
Image: Queensland Brain Institute
Image: Queensland Brain Institute
These vesicles then grow and further compartmentalise, giving rise to the functionally distinct areas of the adult brain.
Forebrain
The forebrain eventually makes up the largest portion of the brain, comprising the:
- cerebral cortex
- basal ganglia
- limbic system (hippocampus, amygdala, hypothalamus)
- thalamus.
These areas are responsible for cognitive capacities such as:
- memory
- learning
- reasoning
- emotions.
As well as the processing of sensory information like:
- vision
- hearing
- touch
- smell
- taste.
Midbrain
The midbrain is the smallest of the three developmental brain regions and is located between the forebrain and the hindbrain.
It contains two main areas, the tectum and the tegmentum.
These are involved in aspects of visual and auditory processing (e.g., involuntary eye movements and the pupillary reflex) as well as sleep and attention.
Hindbrain
The hindbrain is located at the lowest part of the brain. When fully developed, the hindbrain consists of the:
- pons
- cerebellum
- medulla oblongata.
Its functions include integrating sensory and motor information to facilitate controlled motor output for:
- balance
- posture
- coordinated movements
As well as vital autonomous bodily functions such as:
- breathing
- heart rate
- sleep.
The medulla oblongata also acts as the main juncture for nerve signals between the brain and the spinal cord.
Midbrain and hindbrain (not including the cerebellum) are commonly also referred to as the brainstem, i.e., those areas of the brain that govern vital involuntary bodily functions.
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