— Slate - Phineas Gage, Neuroscience’s Most Famous Patient
— Slate - Phineas Gage, Neuroscience’s Most Famous Patient
New brain imaging of psychopaths shows evidence that suggests functional differences in certain brain regions involved in emotion regulation and behavioral control. Parts of the brain called theventromedial prefrontal cortex and amygdalaare two neural regions that are densely interconnected and work together to process and regulate emotion (Davidson, 2002; Kalin et al., 2004). In psychopaths, the circuit between these two parts of the brain functions abnormally. In tests, psychopaths were shown to process differently stimuli for fear conditioning, processing emotions, and moral decision-making (Birbaumer et al., 2005; Kiehl et al., 2001; Glenn et al., 2009). But the story is more complicated than a neural circuit that simply does not activate when it should. The brain is a series of interconnected networks, and it is likely that many other regions are involved in the disorder.
Astroglia are star-shaped cells found in the spinal cord and brain, generally responsible for maintaining homeostasis, as well as contributing to healing from traumatic injuries (among other amazing things).
They’re also beautiful!
All of these are drawn from the Astrocyte article on Wikipedia. For specific info, follow the links attached to each micrograph.
What Is Aphasia? What Causes Aphasia?
Aphasia is a language disorder that negatively affects a person’s ability to talk, understand the spoken word and also their reading and writing. Originating from the Greek word "aphatos" which means speechless, aphasia is a symptom resultant of pre-existing brain damage, such as Alzheimer’s disease or stroke (with over 30% of stroke victims suffering aphasia to some degree).
Originally, aphasia was a term used only to describe complete impairment of the person’s communication and language. At the time the term dysphasia was used to describe partial language impairment, but it has been frequently mistaken for a swallowing disorder, dysphagia. Because of this, the term aphasia has taken on the meaning of both degrees of language impairment.
As there are three types of aphasia, the symptoms can differ for each type. Details of these differences are:
- Global aphasia - All parts of vocal and written interaction are affected. Both writing and reading is impaired, as well as speech and listening.
- Fluent aphasia - Speech is hard/not possible to understand. The ability to speak is not impaired, but the words spoken make no sense (word salad). Writing ability is usually effected in the same way, the writing is flowing but what is actually written is nonsense.
The person suffering from fluent aphasia may become annoyed and irritated if someone has trouble understanding them as they don’t always realize they have a language disorder. As for understanding, people with fluent aphasia more commonly have problems with speech than writing.
- Non-fluent aphasia - With this type, speech is slower and hesitant, the patient also struggles to get their words out. Sentences are rarely completed, and even though some words are missing, what they are saying can be made sense of. Again writing ability is usually the same as speech but comprehension is good.
Someone with non-fluent aphasia has more problems with grammar than words alone. People with this kind of aphasia are more aware of their disorder and may get annoyed when they struggle with words.
What Causes Aphasia?
The part of the brain that controls speech and language recognition is referred to as the language center. It is normally in the part of the brain opposite to side of the hand you write with (e.g. left side of brain for the right handed). These parts of the brain are known asBroca’s area and Wernicke’s area. Aphasia is caused when any of these parts of the brain or the neural pathways connecting them are damaged. This can be a result of the following:
- Traumatic brain injury
- Brain tumor
The type of aphasia is dependent on which part of the brain is damaged. The causes of each type of aphasia are:
- Global aphasia - caused by widespread damage right through the language center.
- Fluent aphasia - usually caused by damage to the temporal lobe (side of brain).
- Non-fluent aphasia - mostly the result of frontal lobe (front of brain) damage.
Disorders Confused with Aphasia:
A variety of other communication disorders may accompany aphasia or occur independently, yet be confused with aphasia. It is important to recognize these disorders and distinguish them from aphasia, as treatments and prognoses may vary.
With dysarthria, a person is unable to produce speech accurately due either to weakness of the muscles involved in speaking or a lack of coordination among these muscles. Dysarthria affects the production, not language itself — which distinguishes it from aphasia.
Dysarthria affects children and adults, with causes including stroke, head injury, cerebral palsy, and muscular dystrophy.
For a person with dysphagia, swallowing is difficult and may cause pain, sometimes making it difficult to take in enough calories and fluids to nourish the body. It occurs most often in the elderly as the result of conditions like Parkinson’s disease, cerebral palsy, stroke, head injury, or cancer.
Dementia is a loss of brain function that affects memory, thinking, language, judgment, and behavior. Some forms of dementia are progressive, such as Alzheimer’s disease. Because language difficulties are often prominent in dementia, it is often confused with aphasia. But the language difficulties in dementia are usually just one symptom of a more widespread intellectual loss.
Cognitive and Automatic Motor Control
Motor control incorporates multiple cortical and subcortical structures. Most important are the connections between the basal ganglia and cortex that are involved in cognitive and automatic aspects of motor control. In PD, loss of DA in the caudal basal ganglia leads to impaired automatic movements involving circuits important in stimulus based habitual learning (red arrows) and over-reliance on cognitive components of motor control and circuits involved in reward based learning (blue arrows).