What Are the 4 Lobes of the Brain?

There are 4 lobes on each hemisphere of the brain: the frontal lobe, the parietal lobe, the temporal lobe, and the occipital lobe. Each lobe performs specific functions in the brain.

1. What Is the Frontal Lobe and Its Function?

1.1. What Is the Structure of the Frontal Lobe?

The frontal lobe is situated at the front of the brain and is the largest lobe (one-third) [1].

It is delimited from the parietal lobe by the central sulcus (fissures or grooves) and from the temporal lobe by the lateral sulcus (Sylvian fissure or lateral fissure).

The frontal lobe is divided into lateral, medial (middle), and orbital surfaces or parts.

Each part or surface is further divided into other parts known as gyri (plural for gyrus) that are also separated by sulci (plural for sulcus).

Each gyrus has a specific function associated with the function of the frontal lobe.

1.2. What Is the Function of the Frontal Lobe?

The frontal lobe has many functions:

• Attention (sustained and prolonged attention over time)
• Executive Function (volition (will), planning, selection, sequential organization, and self-monitoring of action.
• Memory (working memory, learning, and long-term memory
• Language (language processing and production)
• Self-awareness
• Audition (the primary auditory cortex responsible of processing sound is in the frontal lobe)
• Voluntary Motor Movements (the primary motor cortex responsible of voluntary movements is in the frontal lobe)
• Personality (lesions of the frontal lobe have been shown to affect personality)
• Affect and Mood (alterations in the frontal lobe function have been shown to correlate with depression).
• Emotional and Social Response (behavioral response in a specific context)

1.3. What Happens If the Frontal Lobe Is Damaged?

Damages of the frontal lobe have been associated with the following disorders and conditions:

• Attention deficits
• Significant impairment in routine daily life
• Deficits in learning and long-term memory
• Speech and language impairments (Broca’s aphasia, Transcortical Motor Aphasia)
• Sudden and profound changes in personality
• Depression
• Impairment in the ability of recollecting past events and in connecting them with future plans
• Impairment in spatial reasoning and moto skills
• Intellectual impairment
• Disinhibition

2. What Is the Parietal Lobe and Its Function?

2.1. What Is the Structure of the Parietal Lobe?

The parietal lobe is situated between the frontal lobe and the occipital lobe [2].

It is delimited from the frontal lobe by the central sulcus (fissures or grooves), from the occipital lobe by the parieto-occipital sulcus, and from the temporal lobe by the lateral sulcus (Sylvian fissure).

The parietal lobe is divided into lateral and middle surfaces or parts.

The lateral surface includes the postcentral gyrus (primary sensory area), the superior parietal lobule, and the inferior parietal lobule (Wernicke’s area) which contains the supramarginal gyrus and the angular gyrus.

The medial surface includes the paracentral lobule and the precuneus.

2.2. What Is the Function of the Parietal Lobe?

The parietal lobe has many functions including:

• Calculation and arithmetic
• Spatial orientation
• Processing of tactile information (touch perception)
• Tactile discrimination
• Temperature sensing
• Body position and movement
• Understanding of grammatical syntactical (syntax) aspects of language
• Visual and movement coordination

2.3. What Happens If the Parietal Lobe Is Damaged?

Damages of the parietal lobe have been associated with the following disorders and conditions:

• Isolated loss of discriminating sensations also known as cortical sensory syndrome.
• Weakness of one side of the body (hemiparesis)
• Visual field loss
• Loss of eye movements

In addition, damages affecting the parietal lobe of the right hemisphere result in the following symptoms:

• Loss of self-orientation
• Loss of topographic memory (capacity to recall shapes, contours, structure, and design)
• Inability to recognize own condition (anosognosia)
• Inability to dress (dressing apraxia)
• Difficulty to draw or assemble objects (constructional apraxia)
• loss of response to visual stimuli in one half of visual field (hemi-inattention)
• Confusion
• Inability to open the eyes at will (apraxia of eye opening)

Damages that affect the parietal lobe of the left hemisphere result in the following symptoms:

• Language disorder
• Gerstman’ s syndrome (impairment of the ability to write, difficulty learning or comprehending calculation and arithmetic, inability to distinguish hand fingers, left-right disorientation)
• Inability to recognize objects by palpation (tactile agnosia)
• Inability to perform previously experienced movements despite adequate sensory and motor abilities

3. What Is the Temporal Lobe and Its Function?

3.1. What Is the Structure of the Temporal Lobe?

The temporal lobe is situated below the lateral fissure (Sylvian fissure) and is delimitated by the frontal lobe and the parietal lobe by the lateral fissure, and from the occipital lobe by an imaginary line known as the parieto-occipital sulcus [3].

The temporal lobe is divided into 3 horizontal gyri and 4 sulci.

The 3 gyri include the superior temporal gyrus, the middle temporal gyrus, and the inferior temporal gyrus.

The gyri are separated by horizontal sulci (fissures) including the superior temporal sulcus, and the inferior temporal sulcus.

The temporal lobe contains important structures including the limbic lobe, the Wernicke’s area, Broca’s area, and the primary auditory cortex.

The limbic lobe contains the hippocampus and the amygdala that are important for memory, learning, and attention processing, and for unconscious body and emotional states.

Wernicke’s area is important for speech understanding and processing, while Broca’s area is involved in speech production.

The primary auditory cortex is responsible for the processing of auditory information (sound).

3.2. What Is the Function of the Temporal Lobe?

The temporal lobe has many functions including:

• Visual memory
• Memory formation
• Processing sensory inputs associated with audition, vision, taste, and smell
• Emotional response associated with a particular stimulus (sensory input)
• Language recognition (Wernicke’s area)
• Identification and Categorization of stimuli

3.3. What Happens If the Temporal Lobe Is Damaged?

Damages of the temporal lobe have been associated with the following disorders and conditions:

• Impairment in auditory (sound) sensation and perception
• Altered personality and affective behavior
• Impairment of visual perception
• Disturbance in language comprehension
• Impairment of selective attention associated with visual and auditory inputs
• Impairment in speech production
• Changes in sexual behavior

4. What Is the Occipital l Lobe and Its Function?

4.1. What Is the Structure of the Occipital Lobe?

The occipital lobe is the smallest and most posterior lobe of the brain [4].

It is delimited from the parietal and temporal lobes by the parieto-occipital sulcus (fissure) and the lateral parieto-temporal line.

It is divided into superior occipital gyrus, middle occipital gyrus, and inferior occipital gyrus that are separated by two transverse sulci (fissures).

The occipital lobe contains important structures including the primary visual cortex (Broadman area 17 or V1) and the secondary visual cortex (also known as V2).

4.2. What Is the Function of the Occipital Lobe?

The occipital controls visual functions through the following areas:

• The primary visual cortex (V1) is the brain processing hub for visual information.
• The secondary visual cortex (V2) is involved in associating vision with past experience and helps in recognition and appreciation.

5.3. What Happens If the Occipital Lobe Is Damaged?

Damages of the occipital lobe have been associated with the following disorders and conditions:

• Epilepsy
• Visual field defects
• Movement and balance difficulties
• Distortion in the perception of colors, shapes, dimensions, and sizes
• Difficulties recognizing, reading, and writing words
• Hallucinations
• Cortical blindness (total or partial loss of vision with unaffected eyes)
• Defects in object localization within an environment
• Impairment in the recognition of familiar faces or objects

Conclusion

Although we have an overall understanding of how the brain works, there are many things we still do not understand including the function of some specific areas of the brain lobes. Future research in neurosciences will certainly provide new information on the function of this fascinating organ.