Dysfunctions Caused by Thalamus Injury
A thalamus injury refers to an area that is directly above your brain stem but below your cortex. The thalamus receives visual, auditory and somatosensory signals from various areas of your brain. It then routes these signals to a specific area in the cortex to be further processed. Essentially, the thalamus is a central area for sensory information to travel to before arriving at the cortex so any level of injury can be very traumatic.
An unfortunate thalamus injury can produce significant sensory perception distortions which is what is typically seen in autism and cerebral palsy. Problems that are associated with these types of injuries depend directly on the area affected. For example, if visual receiving and processing areas become injured then visual field dysfunction will result. On the other hand, if there is an injury to touch perception, acute pain syndrome will often be seen.
Cerebrovascular accidents, commonly referred to as stroke can cause thalamic syndrome which creates an aching or burning sensation on one half of the affected individual's body. This is often accompanied with an abrupt mood swing.
A thalamus injury can occur after suffering a closed-head injury. When this happens, the individual experiences an all over sense of numbness which advances to episodes of random pain. It is also common for individuals to experience periodic or continuous freezing, burning or crushing sensations, aphasia, outbursts of anger or fear, frontal lobe dysfunction or abusive behavior.
Distortions a Thalamus Injury can Cause
- Sensory Over-Amplification – Environmental stimuli can cause over sensitivity. This is due to the limbic system, thalamus and reticular formation all malfunctioning. This would cause the individual to withdraw or overreact as a defensive strategy because the smallest things in the world seem incredibly overwhelming.
- Sensory Under-Amplification – This individual is under sensitive to environmental stimuli. In this case, the cortex is being under-excited and the individual will often act a though they cannot feel, hear or see due to a deficiency in this area.
- Wide Spectrum Tuning – When this results from a thalamus injury, the cortex is being excited from the three neurological structures which are turning attention toward multiple incoming stimuli. These individuals find it important to ignore background sights and noises, making it important to focus on only one environmental element. The world in this individual's eyes is chaos so they have no choice but to withdraw.
- Internally Focused Sensory Tuning – When this dysfunction is present, the individual is inwardly tuned. The cortex is being excited by stimuli within the individual's own body so they perceive the outside world through an internal haze of stimulation.
- Narrow Spectrum Tuning – The cortex is only being selectively excited from the three neurological structures. This causes the cortex to attend to isolated, limited sensory stimuli. An individual who suffers a thalamus injury and ends up with narrow spectrum tuning will often choose one environmental aspect to devote all of their attention to. For an example, a child will become fixated with one particular spinning toy as they are obsessed and have no interest in any other offered item. These individuals focus so narrowly that they are unable to spread their attention elsewhere.
It is important to understand that individuals who suffer a thalamus injury will often behave in an unexpected way. They will do and say things that would be considered not in their nature prior to the injury. They will often become aggressive or extreme and act in an unacceptable way however, quite often they cannot be held responsible for their actions. The person that they have become is generally completely out of their control and may not realize exactly what they are doing or understand right from wrong.