Biopsych Chapter 16

Dyslexia Overview

• Dyslexia is a specific learning disability that affects reading and language processing.
• It is typically characterized by difficulties with accurate and/or fluent word recognition and by poor spelling and decoding abilities.

Types of Dyslexia

• Two main types are identified: Developmental Dyslexia and Acquired Dyslexia.

Causes of Acquired Dyslexia

• Acquired Dyslexia is caused by brain injury or neurological diseases impacting areas responsible for reading and language.

Prevalence of Developmental Dyslexia

• Developmental Dyslexia occurs in about 5-10% of English speakers, indicating a significant presence within the population.

Gender Disparity

• Developmental Dyslexia is more commonly diagnosed in males than females, showing a gender bias in prevalence.

Causes of Developmental Dyslexia

• Current understanding indicates a mix of genetic and neurobiological factors contributing to its development.

Brain Activity in Dyslexia

• There is a reduction in brain activity in specific areas associated with reading tasks, especially in the left hemisphere.

Research Focus

• Researchers concentrate on understanding the neural mechanisms associated with reading deficits and their relationship to dyslexia.

Deficits in Developmental Dyslexia

• Deficits include difficulties with phonological processing, working memory, and rapid naming.

Acquired vs. Developmental Dyslexia

• Acquired Dyslexia occurs due to injury or illness, while Developmental Dyslexia is present from early childhood and is not a result of external brain damage.

Major Cause of Dyslexia

• There is widespread agreement that phonological processing deficits are the main cause of dyslexia.

Reading Familiar Words

• The lexical route is perceived as the most effective for reading familiar words due to its reliance on stored word representations.

Surface Dyslexia Characteristics

• Individuals with surface dyslexia struggle with recognizing words based on their visual form but can somewhat manage phonetically decoding them.

Deep Dyslexia

• Deep Dyslexia, also known as "semantic dyslexia," involves significant issues with word recognition and comprehension, where patients may produce semantically related errors.

Lexical Procedure Basis

• The lexical procedure relies on the recognition of whole words stored in memory rather than breaking down sounds.

Cognitive Neuroscience of Surface Dyslexia

• Surface dyslexia is characterized by an inability to access irregularly spelled words, leading to a reliance on phonetic decoding, which can result in mispronunciations.

Cognitive Neuroscience of Deep Dyslexia

• Deep dyslexia features an inability to read regular and irregular words fluently, often leading to semantic errors.

Lexical vs. Phonetic Procedures

• Lexical procedures involve recognizing whole words, while phonetic procedures focus on decoding words by their sounds.

Surface Dyslexia Difficulties

• Patients experience trouble reading irregularly spelled words, leading to frequent errors.

Errors in Surface Dyslexia

• Typical errors include misreading words that don’t follow phonetic rules or rely heavily on phonetic decoding strategies.

Deep Dyslexia Pronunciation Challenges

• Patients often face difficulties in pronouncing words accurately due to reliance on semantics rather than phonetics, resulting in additional confusion.