Chapter 16: In the Steps of the `Diagram Makers`

Chapter 16: In the Steps of the ‘Diagram Makers’ Amy Menendez

Definitions 







Aphasia is the loss of a previously held ability to speak or understand spoken or written language, due to disease or injury of the brain. Alexia is a neurological disorder marked by loss of the ability to understand written or printed language, usually resulting from a brain lesion or a congenital defect. Agraphia is a cerebral disorder characterized by total or partial inability to write. Anomia is the inability to name objects or to recognize the written or spoken names of objects.

Broca’s Aphasia 

Broca’s aphasia is a type of aphasia caused by a lesion in Broca's area of the brain. The predominant feature is difficulty in finding and speaking words, yet patients have normal comprehension. Broca’s Area

Wernicke’s Aphasia 

Wernicke’s aphasia is a type of aphasia caused by a lesion in Wernicke's area of the brain and characterized by grammatical but more or less meaningless speech and an apparent inability to comprehend speech. Wernicke’s Area

Conduction Aphasia 

Conduction aphasia is a type of aphasia in which the lesion is assumed to be in the association tracts connecting the various language centers of the brain.

Monsieur S. 









Woke up one morning and could not read his newspaper. Could, however, recognize his own name, and could read figures. Unable to write spontaneously or with dictation. Comprehension of spoken language was normal, but when he spoke he used wrong or malformed words. No difficulty recognizing people or objects.

Angular Gyrus 

The angular gyrus is a region of the inferior parietal lobe of the brain that is involved in the processing of auditory and visual input and in the comprehension of language.

Jules Dejerine 

From studying Monsieur S. Dejerine concluded damage to this area prevents the conversion of representations of the appearance of words and letters into representations of their sounds (alexia), and also the conversion of representations of their sounds into representations of their appearance (agraphia).

Monsieur C. 







Had alexia without agraphia. Although he could write, he was unable to read what he had written, unless he could trace the letters with his fingers. Unable to reproduce print as cursive or cursive as print. Recognized patterns without difficulty.

Dejerine’s Explanation of Alexia 



Because the left visual cortex had been destroyed the letters and words could only have been seen through signals reaching the right visual cortex. For these letters and words to be understood the right visual cortex would have to be transferred to areas of speech in the left hemisphere, but damage to the white matter in the hindermost part of the corpus callosum made this impossible.

Dejerine’s Explanation of Agraphia 

In the final attack on Monsieur C. The new lesions destroyed the angular gyrus and adjoining parts of both the temporal and parietal lobes which explained the agraphia and incomprehensible speech of Monsieur C.

Criticisms of the Diagram-making Approach  





The localization of different functions were questioned. Broca’s aphasia was simply the loss of ‘motor images’ and Wernicke’s aphasia was a result of the loss of ‘auditory images’ failed to account for the characteristic features of each. Although divided speech disorders into categories, and explained through models. The actual cases did not fit into the categories. Preoccupation with pinpointing damaged centres or pathways and deducing the consequences of the damage. (localization approach)

Cognitive Neuropsychologists 



Cognitive Neuropsychology is a branch of neuropsychology that aims to understand how the structure and function of the brain relates to specific psychological processes. It places a particular emphasis on studying the cognitive effects of brain injury or neurological illness with a view to inferring models of normal cognitive functioning. “The most striking contribution of the cognitive neuropsychologists has been to show that the machinery handling language often behaves as if it consists of interacting modules”.

Phonological and Lexical Routes to Reading 

The phonological route to reading is when we learn the phonetics of reading as well as the rules of pronunciation.



The lexical route to reading is when we can read at a glace without sounding out letters or guidance from rules. The spelling and pronunciation is already stored in our brains.

Hyena Yacht Colonel

Deep Alexia and Surface Alexia 



When there is a block in the phonological route, the patient is said to be suffering from phonological alexia or deep alexia. When there is a block in the lexical route the patient is said to be suffering from lexical alexia or surface alexia.

Learning to Use Words Sound Patterns of Words Pathway A

Meanings of Words

Pathway B

Pathway C

Appearances of Written Words

Language Disorders 



She was able to read pronounceable non-words so her phonological reading was intact. However, that couldn’t account for her being able to read words like leopard, tortoise, and liquor. Therefore, the lexical route Progressive Presenile Dementia must include a pathway from the printed word to the word sound that does not depend on comprehension This means pathway B, from sound patterns of words to appearances of written words, must exist!

Language Disorders 



Had the ability to repeat and write down spoken sentences that she could not understand, but could understand what she had written. Inability to understand a sentence after hearing it implies that pathway A, from the sound of word to the meaning of the word, was impaired.

Word-Meaning Deafness

The fact that she could understand a sentence after writing it down implies there is a route from the appearance of written words to the meaning of written words, so pathway C must exist!

Language Disorders 



When reading aloud, patients with Deep Alexia, tend to make semantic, word meaning, mistakes. These mistakes are significant because it not only shows a direct connection between appearance of written words and sound, pathway B, it also shows a direct connection between appearance of written words and the meaning of written words, pathway C.

Right Brain vs. Left Brain 





There is evidence to support the right side of the brain has to do with object recognition, spatial analysis, recognition of musical pitch, timbre, and harmony. Emotional aspects of speech are controlled here. The right half of the brain is responsible for controlling the left hand, and the left visual field.







Gestures used to convey meaning are controlled in the left hemisphere. Spoken language is on the left side of the brain. The left side of the brain is also responsible for controlling the right hand, and processing the right visual field.

Right Brain vs. Left Brain Look at the chart: Say the color not the word. Black Blue Green White Green Red Green Aqua Yellow YellowPink Tan Red Yellow White

The Split Brain 

Roger Sperry published a series of papers in which he described what happened when he disconnected the two hemispheres of the brain in monkeys and cats. Optic Chiasma

Epilepsy and the Split Brain 





This procedure went from research in monkeys and cats to research with humans who had epilepsy. The procedure was performed, except the optic chiasma was not cut. Not only did this prevent seizures from spreading from one hemisphere to another it actually mad the seizures occur less frequently.

Brain Scans 



PET scans allow us to measure changes in local blood flow, glucose consumption and neurotransmitter uptake. MRI scans allow us to measure changes in local blood flow and oxygen content.

What Do These Scans Do For Us? 

These brain scans, specifically the PET scan, have shown us the parts of the brain associated with auditory and visual stimuli.

What Do These Scans Do For Us? 





They have shown us that our brains tend to store information in a phonological rather than visual form. Findings indicate conditions that use the phonological store lead to an increase of blood flow to the left supramarginal gyrus. Also indicate the sub-vocal rehearsal system is associated with Broca’s area.

The supramarginal gyrus is involved with spatial orientation and semantic representation.

What Do These Scans Do For Us? 



These scans also provide us with insight to disorders such as dyslexia. Once we have a full understanding of how these disorders work, we can work to help people who have them cope with them better.