"Aphasia" is a general term for a collection of disorders that affect a person's ability to use language. While quite rare, Wernicke's aphasia (named after physician Carl Wernicke) is easily the most unsettling variety. Those with this condition have no problem with word production—linguistic features like cadence and intonation are unaffected. However, everything spoken is, quite literally, gibberish. Sometimes patients are able to use actual words, albeit incorrectly, but other times the words they use are not real at all. Othertimes, the ability to grasp words and sentences are impaired, while producing connected speech isn’t affected. This type is called “fluent aphasia” or “receptive aphasia.”The scariest part of this condition is that, at the time, patients normally do not realize what they're saying is nonsensical.
This condition occurs when a person sustains damage to the Wernicke's area of the brain, which is one of the two regions primarily responsible for language production.
Although it sounds like something straight out of a Hollywood thriller, people living with Capgras syndrome are under the delusion that a loved one has been replaced by an impostor who looks exactly like them. While this condition most commonly occurs in those with paranoid schizophrenia, it can also be induced by a brain injury or other problems like diabetes and hyperthyroidism.
Its cause is still not entirely known, but researchers hypothesize that it has to do with a disconnect in the brain between the temporal cortex (which helps us recognize faces) and the limbic system (which is responsible for emotion).
For most people with epilepsy, a seizure is a frightening occurence. However, for a rare subset, this event is almost a religious experience. In some cases, this manifests as an overwhelming general feeling of bliss, while others actually may have visual or auditory hallucinations that are percieved as equally blissful. In fact, Russian author Fyodor Dostoevsky said his epileptic seizures were so overwhelmingly beautiful he would give up 10 years of his life for just a few seconds of the sensation.
This powerful feeling of ecstasy typically occurs immediately before a seizure in a period known as an "aura." While most people with epilepsy experience auras, symptoms are typically stressful and disorienting. Researchers believe that ecstatic epilepsy is caused by increased activity in the anterior insula, a region of the brain considered to be the "root' of our subjectivity.
Everyone loses track of time occasionally, but for people with time agnosia, measuring the passing of time is something they struggle with constantly. While those with the condition can still remember the order of events (e.g. they know they ate breakfast before they ate lunch), it's not possible for them to determine how much time has passed between events.
Most commonly, this condition occurs when damage occurs to the temporal lobe or surrounding areas of the brain.
Of all the potential brain disorders, akinetopsia is arguably one of the most dangerous and disorienting—patients with the condition lack the ability to percieve motion. For those with mild akinetopsia, visual trailing is the most common symptom. This involves seeing "phantom" afterimages of an object in motion, similar to a long-exposure photo. However, in severe cases, patients may lack the ability to see any motion whatsoever—making everyday tasks like pouring a liquid or crossing the street extremely difficult.
Lesions on the middle temporal cortex are the most common cause of akinetopsia. This area of the brain is responsible for visual processing, including the perception of motion.
Prosopagnosia is a condition that leaves patients with an inability to remember faces and is sometimes colloquially referred to as "face blindness." Interestingly enough, this disorder doesn't seem to affect any other of a person's visual processing abilities. To cope with this condition, patients rely on other cues to recognize others, including voice, hair color, and clothing.
In most cases, prosopagnosia occurs when patients experience damage to their fusiform gyrus, the section of the brain normally activated when a person sees a face.
Making a major decision is difficult for anyone, but for those with aboulomania, even minor things like deciding what to wear or eat can leave them paralyzed with indescison. To prevent this unpleasantness, people will often go to great lengths to avoid being alone and making decisions, including staying in abusive or dysfunctional relationships. Luckily, some patients can benefit greatly from treatments such as psychotherapy.
The prefontal cortex is the area of the brain responsible for rational decision making, and it seems that in those with aboulomania this region becomes overwhelmed much easier than for other people.
Also known as "alien limb syndrome," somatoparaphrenia is a bizarre condition in which a person doesn't recognize one of their limbs as their own. Despite the overwhelming evidence to the contrary, this disorder causes people to concoct outrageous explanations as to why the offending limb is indeed attached to them. In fact, some people with the condition even consider amputation.
Since the condition normally occurs with the left arm, researchers initially thought that somatoparaphrenia was caused by damage to the corpus callosum, the band of fibers that allows the brain's two hemispheres to communicate. However, current studies indicate that it is more likely caused by damage to the basal ganglia.
As the name implies, mirrored-self misidentification is a disorder in which a person doesn't recognize their own reflection. In some cases, the relflection is perceived as a younger or second version of the person, but in other instances, it's seen as a relative or even a stranger. Like with similar disorders, those with the condition are unaware that they have it and can become aggressive if their belief is challenged.
In most cases, mirrored-self identification occurs because of damage to the right frontal lobe. This brain area is responsible for helping individuals evaluate their beliefs.
Patients with anosognosia are unable to recognize their injuries. However, this isn't simply denial on their part—they literally cannot percieve that they are hurt. This most commonly occurs in stroke patients who have suffered paralysis on one side of the body. When prompted to move their affected limb, patients give excuses ranging from not being in the mood to move it to having a third arm that is unseen but moving.
Not much is known about the exact causes of this condition, but those who experience it typically have damage in the right cerebral hemisphere of the brain.