Why don't people with amnesia forget their language?

Language is stored in different brain systems than the ones damaged by classic amnesia. Vocabulary and grammar are held as semantic memory in the temporal cortex; the motor sequences for speaking are procedural memories handled by Broca's and Wernicke's areas together with the cerebellum and basal ganglia. Amnesia (especially anterograde amnesia) damages the hippocampus, which is needed to form new episodic memories. Since the language circuits are physically separate from the hippocampus, they normally survive intact.

Can people with amnesia forget how to talk?

Generally no. Amnesia patients lose autobiographical and event memories but can usually still speak fluently, read, and understand language. Loss of the ability to speak itself is called aphasia, and it is caused by damage to the language areas of the brain (especially Broca's or Wernicke's area), which is a different condition from amnesia.

What did Patient H.M. teach us about amnesia and language?

Henry Molaison (1926-2008), known in the literature as Patient H.M., underwent a bilateral medial temporal lobectomy in 1953 to treat severe epilepsy. He lost the ability to form new long-term episodic memories, but his language, vocabulary, IQ, working memory, and procedural learning were all preserved. His case established that the hippocampus is critical for forming new declarative memories but not for using language.

What's the difference between amnesia and aphasia?

Amnesia is a loss of memory; aphasia is a loss of language. Amnesia is typically caused by hippocampal or medial temporal lobe damage and leaves language intact. Aphasia is typically caused by stroke or trauma in Broca's area (production), Wernicke's area (comprehension), or surrounding language cortex, and leaves long-term episodic memories intact.

Do amnesia patients forget how to read?

Most do not. Reading relies on a combination of procedural skill and semantic knowledge, both of which are usually preserved in amnesia. (The specific reading impairment called alexia is a separate condition, again caused by damage to language and visual-word-form areas, not by hippocampal amnesia.)

Retrograde Amnesia: How Amnesiacs Remember Their Language?

Table of Contents (click to expand)

Semantic And Episodic Memories
Why Does Language Persist?
The Self

Amnesiacs typically do not forget their native language. Amnesia, especially anterograde amnesia, damages the hippocampus, which is the brain region that forms new episodic memories (specific events from your life). Language itself lives elsewhere: vocabulary and grammar are stored as semantic memory in the temporal cortex, and the motor sequences for actually speaking are procedural memories handled by Broca’s and Wernicke’s areas plus the cerebellum and basal ganglia. None of those circuits are usually destroyed by classic amnesia, so the language survives even when the autobiography does not.

Amnesiacs tend to strongly retain childhood memories, which seem to be cemented by time. That being said, they are known to register new ones, albeit only semantic ones.

50 First Dates is one of the most popular romantic comedies in recent decades. The film is a typical rom-com; it celebrates love, it is (moderately) funny and it is highly unrealistic. Still, it isn’t inaccurate. Barrymore’s portrayal of an amnesiac is surprisingly top notch, unlike protagonists in ridiculous drama or action films who are purged of their amnesia after a blow to the same spot on their head where an earlier blow caused it. This is convenient for the plot of fiction, but not real life.

The notion of memories also entails something that has been a perennial source of introspection and wonder. The essence of the self, our personal identity, has perplexed us since antiquity. The central question is what makes a vague memory of an 8-year-old you packing a school bag with his books the same person as you are at this moment, despite harboring completely different ideologies, appearance, milieu and even biological cells. Despite being biologically and metaphysically different, what makes these two different organisms across time the same being – what makes you you? What accounts for this connectedness?

Descartes believed that personal identity existed separately from our experience, in a Cartesian Ego, a soul. Hume, on the other hand, believed that identity was nothing eccentric, but merely a sum of experiences, a psychological continuity of memories. We are just our thoughts and our memories. Hume believed that it is the nature of memory that dupes us with an illusion of a persisting self, one existing separately from our experiences.

Why Don’t Patients Of Memory Loss Forget Their Language?

Hume’s proposition is remarkable, but more importantly, courageous, for it was implicitly refuting Christianity’s eternal promise. However, his view became progressively more plausible as we became more knowledgeable about the brain’s intricate workings through neurology. One should not confuse amnesia with dementia, where the sense of self somehow erodes. Family members often claim that the patient is no longer his old self. Amnesia, an extensive loss of memory, strangely, spares his victims of this atrocity. Why? Honestly, we don’t know. The mysteries of memory, subjectivity and self-awareness continue to elude us.

References (click to expand)