Breaking Down the Brain Series: 4 - Temporal Lobe

 Temporal Lobe

We continue Breaking Down the Brain by looking at the Temporal Lobe.  The temporal lobes are one of the four main lobes or regions of the cerebral cortex. Structures of the limbic system, including the olfactory cortex, amygdala, and the hippocampus are located within the temporal lobes.

The temporal lobes play an important role in organizing sensory input, auditory perception, language and speech production, as well as memory association and formation.

  • The limbic system supports a variety of functions including emotion, behavior, motivation, long-term memory, and olfaction.
  • The Olfactory Cortex is the sensory system used for the sense of smell.
  • The Amygdala performs a primary role in the processing of memory and emotional reactions.
  • The Hippocampus plays an important role in the consolidation of information from short-term memory to long-term memory and spatial navigation.*

The Functions of the Temporal Lobe include:

  • Auditory Perception
  • Memory
  • Speech
  • Emotional Respones
  • Visual Perception

Kolb & Wishaw (1990) have identified eight principle symptoms of temporal lobe damage:

1) disturbance of auditory sensation and perception,

2) disturbance of selective attention of auditory and visual input,

3) disorders of visual perception,

4) impaired organization and categorization of verbal material,

5) disturbance of language comprehension,

6) impaired long-term memory,

7) altered personality and affective behavior,

8) altered sexual behavior.

Again, damage to the temporal lobe from car crash, fall, assault or other event may not result in impairments of all these areas.  Often there is selective impairments to a few areas making it difficult for others to understand.  This can make relationships and socialization with others difficult. Neuropsychological testing helps medical providers identify impairments and propose treatment.

Seizures of the temporal lobe can have dramatic effects on an individual's personality. Temporal lobe epilepsy can cause perseverative speech, paranoia and aggressive rages (Blumer and Benson, 1975). Severe damage to the temporal lobes can also alter sexual behavior (e.g. increase in activity) (Blumer and Walker, 1975).

You can read more about the temporal lobes in my previous blog posts:

Changes Observed after Brain Injury

Functions Associated with Lobes of the Brain

Psychiatric Issues in Traumatic Brain Injury

Imaging and Diagnosis of Alzheimer's

* Definitions from Wikipedia

Breaking Down the Brain Series: 3 - Parietal Lobe

 The Parietal Lobe

The Parietal Lobe is the upper middle lobe of each cerebral hemisphere, located above the temporal lobe. Complex sensory information from the body is processed in the parietal lobe, which also controls the ability to understand language.  The parietal lobe is a part of the brain positioned above (superior to) the occipital lobe and behind (posterior to) the frontal lobe.

The functions of the Parietal Lobe include:

  • Cognition
  • Information Processing
  • Pain and Touch Sensation
  • Spatial Orientation
  • Speech
  • Visual Perception

Damage to the left parietal lobe

can result in right-left confusion, difficulty with writing (agraphia) and difficulty with mathematics (acalculia). It can also produce disorders of language (aphasia) and the inability to perceive objects normally (agnosia).

  • Agraphia is inability to write resulting from brain damage.
  • Acalculia is a difficulty performing simple mathematical tasks, such as adding, subtracting, multiplying and even simply stating which of two numbers is larger.
  • Aphasia is an impairment of language ability.
  • Agnosia is a loss of ability to recognize objects, persons, sounds, shapes, or smells. It is usually associated with brain injury.*

Damage to the right parietal lobe

can result in neglecting part of the body or space which can impair many self-care skills such as dressing and washing. Right side damage can also cause difficulty in making things (constructional apraxia), denial of deficits and drawing ability.

  • Constructional apraxia is characterized by an inability or difficulty to build, assemble, or draw objects.*

Damage to both the right and left parietal lobes

can cause a visual attention and motor syndrome. This is the inability to voluntarily control the gaze, inability to integrate components of a visual scene (simultanagnosia), and the inability to accurately reach for an object with visual guidance (optic ataxia). 

  • Simultanagnosia is characterized by the inability of an individual to perceive more than a single object at a time.
  • Optic Ataxia is a lack of voluntary coordination of muscle movements.*

Right parietal-temporal lesions can produce significant changes in personality.  Damage to the areas between the parietal lobes and the temporal lobes can also result in changes in personality and memory.

It is very important to understand that a traumatic brain injury from a fall, assault, car crash, or other event, which causes damage to the Parietal Lobe does NOT mean that all the impairments discussed above will definitely manifest.  So you can have some of the impairments and not others.  This where neuropsychological testing becomes vital for doctors in accessing injury and treatment protocol.  

Too many times the people who live, work, socialize or interact with a person, who has sustained parietal lobe damage, do not understand how the person is able to do many things appropriately but cannot do certain other things.  This problem can lead to overlay or manifestation of other problems like depression.

For additional information you can read my prior blog posts:

* Definitions from Wikipedia.

Breaking Down the Brain Series: 2 - Occipital Lobe

 This second installment of the series I am posting about the Anatomy of the Brain deals with the Occipital Lobe.  The occipital lobe is the visual processing center of the mammalian brain.

The primary visual cortex is Brodmann area 17, located in the interior portion of the occipital lobe. Although located at the back of the brain, the Occipital Lobe is responsible for vision which enters the brain through the eyes at the front of the brain.

The Occipital Lobes are positioned at the back region of the cerebral cortex and are the main centers for visual processing. In addition to the occipital lobes, posterior portions of the parietal lobes and temporal lobes are also involved in visual perception. Located within the occipital lobes is the primary visual cortex. This region of the brain receives visual input from the retina. These visual signals are interpreted in the occipital lobes.

The occipital lobes are involved in several functions of the body including:

  • Visual Perception
  • Color Recognition

 They are not particularly vulnerable to injury because of their location at the back of the brain, although any significant trauma to the brain could produce subtle changes to our visual-perceptual system.  Disorders of the occipital lobe can cause visual hallucinations and illusions. Visual hallucinations (visual images with no external stimuli) can be caused by lesions to the occipital region or temporal lobe seizures. Visual illusions (distorted perceptions) can take the form of objects appearing larger or smaller than they actually are, objects lacking color or objects having abnormal coloring. Lesions in the parietal-temporal-occipital association area can cause word blindness with writing impairments (alexia and agraphia).  (Kandel, E., Schwartz, J., & Jessell, T. Principles of Neural Science. 3rd edition. New York: NY. Elsevier, 1991.)

Changes Observed after Brain Injury

 Brain Injury produces observable changes.  Depending on what area of the brain is injured will dictate what the likely changes will look like.

Changes After Frontal Lobe Damage - Because of its location in the anterior part of the head, the frontal lobe is arguably more susceptible to injuries.  This lobe is often cited as the part of the brain responsible for the ability to decide between good and bad choices, as well as recognize the consequences of different actions.

  • Difficulty sequencing
  • Perseveration
  • Difficulties with attention
  • Personality changes
  • Problem-solving difficulties
  • Loss of verbal expression
  • Loss of spontaneity
  • Inflexible thinking
  • Uncontrollable emotional, social, and sexual behavioral changes

Changes After Occipital Damage - A significant functional aspect of the occipital lobe is that it contains the primary visual cortex.

  • Vision defects (visual field cuts)
  • Difficulty visually locating objects
  • Difficulty identifying colors
  • Hallucinations and visual distortions
  • Word blindness
  • Inability to recognize object movement
  • Difficulty reading and writing

Changes After Temporal Damage - The temporal lobe is involved in auditory perception and is home to the primary auditory cortex. It is also important for the processing of semantics in both speech and vision. The temporal lobe contains the hippocampus and plays a key role in the formation of long-term memory.

  • Difficulty understanding spoken words
  • Disturbance of selective attention
  • Short term memory loss
  • Change in sexuality
  • Persistent talking
  • Increased aggressive behavior
  • Difficulty identifying and categorizing objects
  • Difficulty recognizing faces and visually locating objects

Changes After Parietal Damage - The parietal lobe integrates sensory information from different modalities, particularly determining spatial sense and navigation.

  • Reading and writing problems
  • Object naming problems
  • Right/left confusion
  • Math difficulties
  • Inability to focus visual attention
  • Problems with eye-hand coordination
  • Lack of awareness of body parts

Changes After Brain Stem Damage - The brain stem provides the main motor and sensory innervation to the face and neck via the cranial nerves. Though small, this is an extremely important part of the brain as the nerve connections of the motor and sensory systems from the main part of the brain to the rest of the body pass through the brain stem.

  • Decreased breathing capacity
  • Difficulty Swallowing food and fluid
  • Problems with balance and movement
  • Dizziness and vertigo
  • Sleeping difficulties

Changes After Cerebellum Damage - The cerebellum (Latin for little brain) is a region of the brain that plays an important role in motor control. It may also be involved in some cognitive functions such as attention and language, and in regulating fear and pleasure responses,[1] but its movement-related functions are the most solidly established. The cerebellum does not initiate movement, but it contributes to coordination, precision, and accurate timing.

  • Problems with fine movement coordination
  • Loss of ability to walk
  • Inability to grasp objects
  • Tremors 
  • Slurred speech
  • Inability to make rapid movements

 

Functions Associated with Lobes of the Brain

 Skills and Functions Associated with the Lobes of the Brain

The picture of the brain divided into its lobes will be useful as we look at what functions are associated with the Lobes of the Brain.  Injury to the various parts of the brain will like impair those functions associated with the parts.

Any brain function can be disrupted by brain trauma: excessive sleepiness, inattention, difficulty concentrating, impaired memory, faulty judgment, depression, irritability, emotional outbursts, disturbed sleep, diminished libido, difficulty switching between two tasks, and slowed thinking. Sorting out bonafide brain damage from the effects of migraine headaches, pain elsewhere in the body, medications, depression, preoccupation with financial loss, job status, loss of status in the community, loss of status in the family, and any ongoing litigation can be a formibable task.

         

 Frontal Lobe

  • Controls Attention
  • Motivation
  • Emotional Control
  • Guide/control social behavior
  • Judgment
  • Problem Solving
  • Decision Making
  • Expressive Language
  • Motor integration
  • Voluntary movement

Occipital Lobe

  • Visual perception
  • Visual input
  • Reading (the perception and recognition of printed words)

Cerebellum

  • Coordination of voluntary movement
  • Balance and equilibrium

Temporal Lobe

  • Memory
  • Receptive language
  • Language comprehension
  • Musical awareness
  • Sequencing skills

Parietal Lobe

  • Tactile perception
  • Awareness of spatial relations
  • Academic skills

Brain Stem

  • Autonomic nervous system (heart rate, breathing, temperature, etc)
  • Level of alertness

Injury to the various lobes in a car, motorcycle or truck accident can impair the functions listed. Typically the frontal lobe is injured in whiplash type injures.  But other areas can be injured as well.

Unfortunately, because of their location, the frontal lobes are often injured in traumatic events. The lobes can be pushed forward into the bony ridges in the front of the skull, resulting in bruising and tearing. Because of their size, frontal lobes can also be twisted and injured diffusely in a high speed accident

Source: Brain Injury Association of America http://www.biausa.org