Forebrain, midbrain, and hindbrain structures
Forebrain, midbrain, and hindbrain structures
The brain and its parts can be divided into three main categories: the forebrain, midbrain, and hindbrain.
Forebrain structures
The two hemispheres of the cerebral cortex are part of the forebrain, which is the largest part of the brain. The forebrain contains the cerebral cortex and a number of other structures that lie beneath the cortex (called subcortical structures): thalamus, hypothalamus, pituitary gland, and the limbic system (collection of structures).
The cerebral cortex, which is the outer surface of the brain, is associated with higher level processes such as consciousness, thought, emotion, reasoning, language, and memory.
Lobes of the brain
Each cerebral hemisphere can be subdivided into four lobes (frontal, parietal, temporal, and occipital), with each associated with different functions. The frontal lobe is located in the forward part of the brain, extending back to a fissure known as the central sulcus.
The frontal lobe is involved in reasoning, motor control, emotion, and language. It contains the motor cortex, which is involved in planning and coordinating movement; the prefrontal cortex, which is responsible for higher-level cognitive functioning; and Broca's area, which is essential for language production.
The temporal lobe, (temporal means 'near the temples') is located on the side of the head , and is associated with hearing, memory, emotion, and some aspects of language.
The auditory cortex, the main area responsible for processing auditory information, is located within the temporal lobe. Wernicke's area, important for speech comprehension, is also located here.
Individuals with damage to Broca's area have difficulty producing language, those with damage to Wernicke's area can produce sensible language, but they are unable to understand it.
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The occipital lobe is located at the very back of the brain, and contains the primary visual cortex, which is responsible for interpreting incoming visual information.
The occipital cortex is organised retinotopically, which means there is a close relationship between the position of an object in a person's visual field and the position of that object's representation on the cortex.
Other areas of the forebrain
Other areas of the forebrain, located beneath the cerebral cortex, include the thalamus and the limbic system. The thalamus is a sensory relay for the brain.
All of our senses, with the exception of smell, are routed through the thalamus before being directed to other areas of the brain for processing.
The limbic system
The limbic system is involved in processing both emotion and memory. Interestingly, the sense of smell projects directly to the limbic system; therefore, not surprisingly, smell can evoke emotional responses in ways that other sensory modalities cannot. The limbic system is made up of a number of different structures, but three of the most important are the hippocampus, the amygdala, and the hypothalamus.
The hippocampus is an essential structure for learning and memory. The amygdala is involved in our experience of emotion and in tying emotional meaning to our memories. The hypothalamus regulates a number of homeostatic processes, including the regulation of body temperature, appetite, and blood pressure.
The hypothalamus also serves as an interface between the nervous system and the endocrine system and in the regulation of sexual motivation and behaviour.
The midbrain structure
The midbrain is comprised of structures located deep within the brain, between the forebrain and the hindbrain. The reticular formation is centered in the midbrain, but it actually extends up into the forebrain and down into the hindbrain. The reticular formation is important in regulating the sleep/wake cycle, arousal, alertness, and motor activity.
The substantia nigra (Latin for 'black substance') and the ventral tegmental area (VTA) are also located in the midbrain. Both regions contain cell bodies that produce the neurotransmitter dopamine, and both are critical for movement.
Degeneration of the substantia nigra and VTA is involved in Parkinson's disease. In addition, these structures are involved in mood, reward, and addiction.
The hindbrain structure
The hindbrain is located at the back of the head and looks like an extension of the spinal cord. It contains the medulla, pons, and cerebellum. The medulla controls the automatic processes of the autonomic nervous system, such as breathing, blood pressure, and heart rate.
The word pons literally means 'bridge', and as the name suggests, the pons serves to connect the brain and spinal cord. It also is involved in regulating brain activity during sleep. The medulla, pons, and midbrain together are known as the brainstem.
The cerebellum (Latin for 'little brain') receives messages from muscles, tendons, joints, and structures in our ear to control balance, coordination, movement, and motor skills.
The cerebellum is also thought to be an important area for processing some types of memories. In particular, procedural memory, or memory involved in learning and remembering how to perform tasks, is thought to be associated with the cerebellum.
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