Hemispatial neglect – This is the failure to be aware of objects to one side of space. This is usually the contralesional side so if the righ side of the brain has been affected by a lesion than the neglect will be to the left and if the left side of the brain has been affected by a lesion the neglect will be to the right.
Neglect is most prominent and long lastinig in right hemisphere lesions of the brain and this can be especially after a stroke.
(Below is the link to a video of an example of a person whp has hemi spatial neglect drawing a picture)
Cognitive deficits underlying neglect
è Many different cognitive deficits either alone or combined
è Deficit in directing attention to the left
è Impaired representation of space
è Direcetional motor impairment patients could experience difficulty in initiating or programming leftward movements In addition to these lateralised impairments (worse tothe left following right-hemisphere stroke), neglect syndrome also consists of non-spatially lateralised deficits, involving both sides of space. Different patients may suffer different combinations of lateralised and non-lateralised deficits, depending upon the precise location and extent of their lesions.
è Impairments in sustained attention
è Bias to local features in the visual scene
è Deficit in spatial working memory
è Prolonged time- course of visual processing
Blindsight is the term used when people are perceptually blind in particular area of the visual field they are able to respond to visual stimuli. Blindsight is caused by injury to the occipital lobe this is the part of the brain that is responsible for vision. Type 1 blindisght subjects have no awareness to any stimuli but there able to make prediction which are at levels to high to be by chance aspects of visual stimulus such as location or the type of movement a stimulus is displaying this is usually in situations where response is forced or in a situation where they must guess. Type 2 blindsight is when the patient has awareness of movement within the blind area but they have no visual perception. This could be due to the patient being aware of their eyes tracking motion which all the person is blindsighted will still function normally.
(An example and explanation further of blindsight can be seen in the video below) http://www.youtube.com/watch?v=sq6u4XVrr58&list=PL361F982E5B7C1550&index=1
No comments:
Post a Comment