Which Hemisphere of the Brain is Dominant for Language?

Profile of brain (left side)
The left side of the brain houses the machinery for language. BSIP/UIG/Getty Images

The brain has two hemispheres which are two identical appearing halves. The functions of the right hemisphere and the left hemisphere virtually mirror each other, with the right side controlling half of the body's movement, sensation, vision and hearing, while the left side controls the other half of these functions. However, one hemisphere is referred to as the 'dominant' hemisphere.

The dominant hemisphere is the area of the brain the controls speech, mathematical abilities and logical skills.

The non-dominant hemisphere is responsible for creativity, including art and imagination. For right handed individuals, the dominant hemisphere is typically on the left side. For left handed individuals, the dominant hemisphere may be on the right side, and this is why strokes affect left handed people differently than they affect right handed people. 

When a person experiences a stroke, brain tumor or injury that affects the dominant side of the brain, the ability to use language is disrupted.

The Lobes of the Brain

Each hemisphere of the brain is divided into functional sections known as lobes. There are four lobes in each half of the brain. They are:

  • Frontal lobe – located at the front of the brain, right behind the forehead. The frontal lobe is quite large, occupying about 1/3 of the brain's total mass, and it controls personality, behavior, emotional regulation and the ability to plan, solve problems and organize.
  • Parietal lobe – located near the back and top of the head, above the ears. The parietal lobe controls the ability to read, write and understand spatial concepts.  The function of the left and right parietal lobes do not completely mirror each other, with the dominant parietal lobe controlling speech and logic, while the non-dominant parietal lobe controls spatial skills and creativity. In fact, a stroke affecting the non-dominant parietal lobe can produce its own set of problems, including disorientation and an inability to recognize one's own body.
  • Occipital lobe – a small region located at the back of the head. The occipital lobe is responsible for integration of vision.
  • Temporal lobe – located at the side of the head above the ears and below the frontal lobe. The temporal lobe controls hearing, memory, speech, and comprehension.

 

People who have experienced brain injuries to the dominant hemisphere typically experience problems on the opposite side of their body, as well as trouble with language, which is called aphasia.

People who have experienced brain injuries to the non-dominant hemisphere typically experience problems on the opposite side of their body, as well as problems with spatial judgement and with understanding and remembering things.

Aphasia can affect the ability to find the right words, the ability understand what others are saying and the ability to read or write.

Types Of Aphasia

The language areas of the brain include several structures that are located in the frontal, temporal and parietal lobes. A stroke or another injury to any of these specialized language regions, which include Broca's area, Wernicke's area and the arcuate fasiculus, can cause specific types of aphasia which correspond to the specific language region of the brain affected by the stroke or brain injury.

Some of the most common types of aphasia include:

  • Expressive aphasia, also known as Broca’s aphasia – the inability to speak in a fluent and clear way.
  • Receptive aphasia, also known as Wernicke’s aphasia – the inability to understand the meaning of spoken or written language. Often, people who have Wernicke's aphasia can speak fluently, but speak with words and phrases that do not make sense.
  • Anomic or amnesia aphasia – the inability to find the correct name for objects, people, or places
  • Global aphasia – the inability to speak or understand speech, read or write

Management Of Aphasia

Recovery from aphasia is possible.

The most common form of treatment is speech therapy. Other kinds of therapy include:

At home therapy, to support aphasia recovery may include:

  • Playing word-based games
  • Asking questions that require a yes or no
  • Cooking a new recipe
  • Practicing writing
  • Reading or singing out loud

Communicating With Stroke Survivors Who Have Aphasia

While it may be difficult to communicate, people with aphasia have several options when interacting with others.

Some of these options include:

  • Using pictures to make conversations easier
  • Having a conversation in a quiet, non-distracting area
  • Drawing or writing
  • Showing people what works best
  • Connecting with people by email or blog
  • Showing a card that explains your condition to others

Conversely, for those people without aphasia, communicating with stroke survivors who have aphasia can be made easier with some of the following methods:

  • Using pictures or props to make conversation
  • Drawing or writing
  • Speaking simply and slowly

A Word From Verywell

The dominant hemisphere of the brain is usually the hemisphere opposite your dominant hand, and it is most associated with language and with logical skills. Aphasia is an 'invisible' problem that is difficult to live with. However, the majority of stroke survivors who have aphasia experience some recovery through  a natural healing process called neuroplasticity, which is encouraged through rehabilitative therapy after a stroke.

Sources:

A contemporary framework of language processing in the human brain in the context of preoperative and intraoperative language mapping, Middlebrooks EH, Yagmurlu K, Szaflarski JP, Rahman M, Bozkurt B, Neuroradiology. 2017 Jan;59(1):69-87

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