Neglect - blindsight

Neglect in dyslexia

Not only is neglect a spatial disorder it can be found in words

-the case of NT

- AGE 9 – diagnosed of having language problems (Friedman and Nachman – Katz 2004)

- Did not have any visual brain damage or abnormities –but had left word base neglect dyslexia 

-  He was unable to read the left side of words – this was demonstrated through his drawing

-His native language is Hebrew – so he wrote from left to right- so when he write he  leave out or substitute the final words of single letters on the left hand side  – finding show 96%   of his words show these irregularities

- When giving pair of words or sentences – he neglect the left part of the word but not the whole word on the left hand side of the paper

- Improvement are made – by making the neglect word part different colour or making it flash (in other world making it stand out)- also by presented the word vertically than horizontally

-finally does not sown neglect for numbers or symbols

Neglect

Spatial neglect – is the inability to respond, report or attend to the stimuli or event that is in the opposite side of the brain injury

The effect of neglect can happen after months and years of the lesion.

Damaged to the right hemisphere  can lead to neglect of stimuli  on the left hand side and damage to the left hemisphere can lead to neglect of the stimuli on the right however this is not as serve as right damage .

Short term memory * spatial working memory

Short term memory can also appear with neglect symptoms when there is damage to the right parietal lobes  

A study was conducted to test the different in impairment with those that have right neglect and non parietal damage with those with parietal damages using a imagery test that consist of a map of familiar piazzas

Results show that those that had right neglect with parietal damager were significantly more impaired than those that had no injury to the parietal lobe    

Not being able to hold spatial information in the working memory can lead to patients being unable to remember the locations of stimuli- Malhotra et al 2004

Case study

Patient BI

Symptoms of left neglect and right temporal haemorrhage- lead to impairment of spatial location - when giving a visual search task e.g. – mark as many T that u see on the page that are among mix letters  -results show that repeatedly search on the right side-  returned to item that were already noted and saw them as new items

Results show that subtle memory deficit (damage) may affect the performances   with performances of neglect patient 

In regard to the different type of neglect they can be defined by their underling mechanising:

-inattention underlies sensory and perceptual neglect

- Disorder if action and intention underling motor neglect

-representation underlies the neglect of the visual and metal images

Examples of neglect

Difficulties in reading the time

Missing food on one side of the place

Dressing up on one side of the body

 Patient are normal unaware of this behaviour – (anasagnosia) until it pointed out to them

 How to test for spatial neglect

Test

Line bisection – patient are giving lines that are vertical or horizontal and are instructed to put a mark in the middle of the line those that have neglect mark the line closer to the right side when the line is horizontal and the upper end of the line when it is vertical –

Reducing spatial neglect

Recovery can be slow – from 18^th to indefinably

Flashing a red light to the left side of a patient when they are reading copying or cancelling reduces neglect – this works because patient pay attention to one side of an imagery task

Making salient on the right hand side less important to can also reduce neglect  

Vibrating the left posterior neck muscles - this stimulate the neck muscles to generate a body centred frame, the vibration corrects the displaced body- centred frame

Caloric vestibular stimulation – it elicit a vestibular ocular reflex – this can reduce eye movement in the opposite direction to the Attention bias

Opokinetic stimulations – improves voluntary eye gaze direction  

Result 

17 of out of 18 improved when giving spatial neglect test – improvement were short term

These strategies seem to be used rectify inability to automatically to shift attention to the neglect side

 Location of lesions is the spatial neglect 

Lesions are found in the right parieto –temporal cortex

Injury   the inferior and temporal cortex

Damage to the basal ganglia and thalamus following a subcortical stroke – all linke to sensory neglect 

Conception to explain neglect

Pragmatic map - Damage to the perceptuomotor cortical and subcortical can lead to neglect  when they are stimulated this activate spatial awareness – each map have different mechanism and responsibilities for head arm and leg movement