Brain Anatomy and Function
Hemisphere Brain Functions
The brain is divided into two halves (hemispheres). Usually, the left half of the brain controls the right side of the body. The right half of the brain controls the left side of the body.
LEFT BRAIN DAMAGE
Problems seen on the right side of the body.
RIGHT BRAIN DAMAGE
Problems seen on the left side of the body.
THE BRAIN VIEWED FROM ABOVE
- judging the position of things in space
- knowing body position
- understanding and remembering things we do and see
- putting bits of information together to make an entire picture
- controls the left side of the body
- understanding and use of language (listening, reading, speaking and writing)
- memory for spoken and written messages
- detailed analysis of information
- controls the right side of the body
Frontal Lobes
The frontal lobes are considered our emotional control center and home to our personality. There is no other part of the brain where lesions can cause such a wide variety of symptoms (Kolb & Wishaw, 1990). The frontal lobes are involved in motor function, problem solving, spontaneity, memory, language, initiation, judgement, impulse control, and social and sexual behavior. The frontal lobes are extremely vulnerable to injury due to their location at the front of the cranium, proximity to the sphenoid wing and their large size. MRI studies have shown that the frontal area is the most common region of injury following mild to moderate traumatic brain injury (Levin et al., 1987).
Functions:
- How we know what we are doing within our environment (Consciousness).
- How we initiate activity in response to our environment.
- Judgments we make about what occurs in our daily activities.
- Controls our emotional response.
- Controls our expressive language.
- Assigns meaning to the words we choose.
- Involves word associations.
- Memory for habits and motor activities.
Observed Problems:
- Loss of simple movement of various body parts (Paralysis).
- Inability to plan a sequence of complex movements needed to complete multi-stepped tasks, such as making coffee (Sequencing).
- Loss of spontaneity in interacting with others.
- Loss of flexibility in thinking.
- Persistence of a single thought (Perseveration).
- Inability to focus on task (Attending).
- Mood changes (Emotionally Labile).
- Changes in social behavior.
- Changes in personality.
- Difficulty with problem solving.
- Inablility to express language (Broca's Aphasia).
Parietal Lobes
The parietal lobes can be divided into two functional regions. One involves sensation and perception and the other is concerned with integrating sensory input, primarily with the visual system. The first function integrates sensory information to form a single perception (cognition). The second function constructs a spatial coordinate system to represent the world around us. Individuals with damage to the parietal lobes often show striking deficits, such as abnormalities in body image and spatial relations (Kandel, Schwartz & Jessel, 1991).
Functions:
- Location for visual attention.
- Location for touch perception.
- Goal directed voluntary movements.
- Manipulation of objects.
- Integration of different senses that allows for understanding a single concept.
Observed Problems:
- Inability to attend to more than one object at a time.
- Inability to name an object (Anomia).
- Inability to locate the words for writing (Agraphia).
- Problems with reading (Alexia).
- Difficulty with drawing objects.
- Difficulty in distinguishing left from right.
- Difficulty with doing mathematics (Dyscalculia).
- Lack of awareness of certain body parts and/or surrounding space (Apraxia) that leads to difficulties in self-care.
- Inability to focus visual attention.
- Difficulties with eye and hand coordination.
Temporal Lobes
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.
Functions:
- Hearing ability
- Memory aquisition
- Some visual perceptions
- Catagorization of objects.
Observed Problems:
- Difficulty in recognizing faces (Prosopagnosia).
- Difficulty in understanding spoken words (Wernicke's Aphasia).
- Disturbance with selective attention to what we see and hear.
- Difficulty with identification of, and verbalization about objects.
- Short-term memory loss.
- Interference with long-term memory
- Increased or decreased interest in sexual behavior.
- Inability to catagorize objects (Catagorization).
- Right lobe damage can cause persistant talking.
- Increased aggressive behavior.
Occipital Lobes
The occipital lobes are the center of our visual perception system. 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, such as visual field defects and scotomas.
Functions:
Observed Problems:
- Defects in vision (Visual Field Cuts).
- Difficulty with locating objects in environment.
- Difficulty with identifying colors (Color Agnosia).
- Production of hallucinations
- Visual illusions - inaccurately seeing objects.
- Word blindness - inability to recognize words.
- Difficulty in recognizing drawn objects.
- Inability to recognize the movement of an object (Movement Agnosia).
- Difficulties with reading and writing.
Cerebellum
The cerebellum is involved in the coordination of voluntary motor movement, balance and equilibrium and muscle tone. It is located just above the brain stem and toward the back of the brain. It is relatively well protected from trauma compared to the frontal and temporal lobes and brain stem.
Functions:
- Coordination of voluntary movement
- Balance and equilibrium
- Some memory for reflex motor acts.
Observed Problems:
- Loss of ability to coordinate fine movements.
- Loss of ability to walk.
- Inability to reach out and grab objects.
- Tremors.
- Dizziness (Vertigo).
- Slurred Speech (Scanning Speech).
- Inability to make rapid movements.
Brain Stem
The brain stem plays a vital role in basic attention, arousal, and consciousness. All information to and from our body passes through the brain stem on the way to or from the brain. Like the frontal and temporal lobes, the brain stem is located in an area near bony protrusions making it vulnerable to damage during trauma.
Functions:
- Breathing
- Heart Rate
- Swallowing
- Reflexes to seeing and hearing (Startle Response).
- Controls sweating, blood pressure, digestion, temperature (Autonomic Nervous System).
- Affects level of alertness.
- Ability to sleep.
- Sense of balance (Vestibular Function).
Observed Problems:
- Decreased vital capacity in breathing, important for speech.
- Swallowing food and water (Dysphagia).
- Difficulty with organization/perception of the environment.
- Problems with balance and movement.
- Dizziness and nausea (Vertigo).
- Sleeping difficulties (Insomnia, sleep apnea).
Reprinted with Permission
