Primary Effects


Traumatic brain injury (TBI) can significantly affect many cognitive, physical, and psychological skills. Physical deficit can include ambulation, balance, coordination, fine motor skills, strength, and endurance. Cognitive deficits of language and communication, information processing, memory, and perceptual skills are common. Psychological status is also often altered. Adjustment to disability issues are frequently encountered by people with TBI.

In many MTBI cases, the person seems fine on the surface, yet continues to endure chronic functional problems. Some people suffer long-term effects of MTBI, known as postconcussion syndrome (PCS). Persons suffering from PCS can experience significant changes in cognition and personality.

Most traumatic brain injuries result in widespread damage to the brain because the brain ricochets inside the skull during the impact of an accident. Diffuse axonal injury occurs when the nerve cells are torn from one another. Localized damage also occurs when the brain bounces against the skull. The brain stem, frontal lobe, and temporal lobes are particularly vulnerable to this because of their location near bony protrusions.

The brain stem is located at the base of the brain. Aside from regulating basic arousal and regulatory functions, the brain stem is involved in attention and short-term memory. Trauma to this area can lead to disorientation, frustration, and anger. 

The limbic system, higher up in the brain than the brain stem, helps regulate emotions. Connected to the limbic system are the temporal lobes which are involved in many cognitive skills such as memory and language. Damage to the temporal lobes, or seizures in this area, have been associated with a number of behavioral disorders. 

The frontal lobe is almost always injured due to its large size and its location near the front of the cranium. The frontal lobe is involved in many cognitive functions and is considered our emotional and personality control centre. Damage to this area can result in decreased judgement and increased impulsivity.

Functions of the brain

All the activities we perform each day, whether physical or mental, are directed by different parts of our brains. It is important that you become familiar with brain function to better understand how therapies, created by rehabilitation professionals, help brain injured patients. In order for you to better understand how the rehabilitation process works we will guide you through the different parts of the brain and indicate some of the functions and problems resulting from injury.

The brain has many parts including the cerebral cortex, brain stem, and cerebellum. By listing some of the functions of each part of the brain, we will provide an overview of what problems occur after injury to these parts. It is important to understand that the brain functions as a whole by interrelating its component parts. The injury may only disrupt a particular step of an activity that occurs in a specific part of the brain. The interruption of that activity at any particular step, or out of sequence, can reveal the problems associated with the injury. Below is a list of functions and deficits or problems revealed when injury occurs at particular locations. The terms in parenthesis are the professional terms used to describe the deficit. Please refer to the Brain Map at the bottom of this page for an illustration of the main areas of the brain.


The cerebral cortex is the folded gray tissue that covers the surface of each cerebral hemisphere. It is responsible for language, music, calculations, imagining, thinking and planning. It controls our ability to move our arms, legs, head, eyes, tongue—any body part we can move deliberately. It determines our intelligence, emotions, and personality. It also processes sensory information for vision, hearing, and speech. Almost everything we do consciously depends on the cortex.


Your brain is divided into two halves, or hemispheres. A deep groove runs down its centre, separating the two hemispheres. Each hemisphere is almost a mirror image of the other but each has a slightly different pattern of bumps and grooves. And each hemisphere controls the opposite side of the body and is associated with different functions. The left hemisphere is specialized for speech, writing, language, and calculation. The right hemisphere is specialized for spatial abilities, face recognition, and some musical abilities.

Corpus Callosum

The corpus callosum is a thick bundle of nerve fibers that connects the two hemispheres of the brain. It allows the two hemispheres to communicate, which is important for coordinating left- and right-brain functions.


The cerebrum is the largest part of the brain and controls all conscious thoughts, experiences, and actions. It is divided into right and left hemispheres, which are joined by the corpus callosum. Its outer folded layer is called the cerebral cortex.


The hypothalamus is a small structure below the thalamus that regulates body conditions such as body temperature, thirst, hunger, and blood pressure. It also controls the release of hormones from the pituitary gland, linking the nervous system to the endocrine system.


The thalamus serves as a two-way relay station for messages traveling into and out of the brain. It filters and directs most sensory information from outside the body to appropriate parts of the brain. This walnut-sized structure also plays a role in storing and retrieving memories.

Pre-frontal Cortex

The prefrontal cortex in the forward part of the frontal lobe helps control the highest levels of thinking, such as planning, reasoning, and imagination. It is also involved in conscious functions such as empathy, self-perception, and the ability to interact appropriately with others. This part of the brain is especially well-developed in humans.

Frontal Lobes: 

The frontal lobes are located behind the forehead. This area of the brain is associated with higher-level thinking, such as problem solving, reasoning, and some aspects of speech. It also contains the motor cortex, which controls voluntary movement.


  • How we know what we are doing within our environment (Consciousness)
  • How we initiate activity in response to our environment
  • Judgements 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 on the top of the head process senses like touch, pain, temperature, pressure, and spatial awareness. They are also associated with voluntary movement, attention, language, and some mathematical abilities.


  • 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

Occipital Lobes: 

The occipital lobes at the back of the brain interpret visual information like color, light, shape, and movement. The left and right occipital lobes interpret messages from the opposite halves of each eye. For example, the left occipital lobe receives visual signals from the left half of the retinas in both the right and left eyes, and these halves, in turn, see objects in the opposite (right) halves of the visual field. The two lobes are connected, so the information is combined to produce a single image.

  • Vision

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

Temporal Lobes: 

The temporal lobes, above the ears, are involved in hearing,identifying objects, understanding language, and storing memories. They also play a role in emotions.


  • Hearing ability
  • Memory acquisition
  • Some visual perceptions
  • Categorization 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 (Categorization)
  • Right lobe damage can cause persistent talking
  • Increased aggressive behavior

Deeper inside the human brain

Delve beneath the cerebrum, and you'll find other essential structures. These parts of the brain, including the limbic system, the brain stem, and the cerebellum, are mostly involved in unconscious actions. Some control body functions such as heart rate and breathing, while others regulate your body temperature and sleep cycle. Still others maintain your balance or relay sensory information between parts of the brain.

Brain Stem: 

The brain stem is the “stalk” of the brain below the cerebrum that connects to the spinal cord. It controls processes basic for survival, such as heart rate, breathing, digestion, and sleep. It is the main route of communication between the rest of the brain, the spinal cord, and the nerves that run throughout the body.It also has its own set of nerves that send and receive signals to the face, mouth, tongue, eye muscles, ears, and balance-sensing vestibular organs.


  • 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)


The cerebellum is the second largest part of the brain. It controls posture and balance. Replace this with, "It also helps with the timing and coordination of our movements, making them smooth and precise. Recent research also suggests a role in higher cognitive processes.


  • 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

Obtaining a general understanding of the brain and its functions is important to understanding the rehabilitation process. The rehabilitation professional is concerned with the whole person. The identification of individual problems gives the rehabilitation team areas in which to focus treatment plans. All of these plans are designed to work toward the rehabilitation of the whole person. Each problem area affects other areas and many times resolving one problem has a major impact on other problems. For example, reestablishing postural balance and eliminating dizziness greatly enhances concentration and attention which allows for improved cognition and problem solving.


The limbic system (or Paleomammalian brain) is a set of brain structures including the hippocampus, amygdala, anterior thalamic nuclei, septum, limbic cortex and fornix, which seemingly support a variety of functions including emotion, behavior, long term memory, and olfaction.

The limbic system operates by influencing the endocrine system and the autonomic nervous system. It is highly interconnected with the nucleus accumbens, the brain's pleasure center, which plays a role in sexual arousal and the "high" derived from certain recreational drugs. 

The limbic system is also tightly connected to the pre-frontal cortex. 

The limbic system is a ring-shaped group of structures involved in emotions, instincts, and memory formation. Together with the brain stem, it manages essential survival functions such as temperature, blood pressure, heart rate, and blood sugar.


The amygdala plays a key role in emotions and forming emotional memories. This almond-shaped structure integrates your senses and links them with your emotions. It also affects basic behaviors such as feeding, sexual arousal, and the “fight-or-flight” reaction to stress.


The endocrine system is the system of glands, each of which secretes a type of hormone directly into the bloodstream to regulate the body. 

Hormones regulate various human functions, including metabolism, growth and development, tissue function, and mood.


The hippocampus is a seahorse-shaped brain structure involved in memory, learning, and emotion. It forms new memories and organizes them with related memories and emotions.

Pituitary Gland

The pea-sized pituitary gland is one of the key structures in the endocrine system. It releases the hormones that regulate growth, sexual development, and the activity of other endocrine organs in the body. Found in the center of the skull, it works closely with the nearby hypothalamus.

Pineal Gland

The pineal gland regulates the body’s internal clock. It monitors the amount of incoming light and produces the hormone melatonin, which affects your sleep-wake cycle. This small, cone-shaped gland is part of the endocrine system.

Dysfunctions of the endocrine system can be viewed here.