OPTA 204(Visual Perception, Agnosia, Apraxia, Acalculia)
What is Perception
Perception refers to the way sensory information is organized, interpreted, and consciously experienced.
What is Visual Memory
Remembering visual information
What is Form Discrimination
Recognizing objects are the same even if they are different in size or orientation
What is Visual Closure
Recognizing two objects are the same even if a part is missing
What is Depth Perception
Ability to perceive the relative distance between objects in one’s visual field. ex how far away something is from a person
What is Figure Ground Perception
Ability to perceive foreground vs. background
what is Spatial Relations
How one object is located in space in relation to another object, ex how far away/ where objects are in relation to another
Form Discrimination
- aspect include: colour, shape**, edge, motion.
- processing of form occurs in parietal and temporal lobe visual areas
- difficulty notiing small differences in form
Form Discimination Rehab
- Sorting activities
- Shape drawing activities
-Important in childhood development. Is child able to complete these tasks at an appropriate age?
Why is it important?
Depth Perception(stereopsis)
-Helps person to locate objects
-Assists with navigating stairs and driving
-Allows for accurate hand movements with visual guidance
-What other day to day tasks would be difficult with impaired depth perception? placing thing down,
-Visual acuity and ocular alignment are required
-Parietal lobe is responsible
-Acquired at 2 months of age
-Can be basically tested by asking about location of things in the natural environment
Treatment for Depth Perception
-Restorative Approach: Get the patient to use tactile and kinesthetic sense to guide their movements, eventually rely less on other systems Ie. prior to transferring into a chair feel the location
-Compensatory/Adaptive approach:
Figure Ground Perception
- Distinguishing foreground vs background
- Foreground is the figure you are focussing on
- Relies on color, luminance, depth, texture, motion etc.
- Helps to visually organize an environment
- Impairments in figure ground would make it difficult to find something in a busy drawer or to find the sleeve of a shirt that is all the same color
- Figure ground exercise
Treatment For FGP
- Restorative Approach:Scatter objects in front of client, have them pick out an object and name it, Interpret drawings
- Compensatory/Adaptive approach: Declutter, Mark things with colored tape
Spatial Relation
- Understanding where and how objects exist in relation to other objects
- Spatial relationships help us to orient ourselves in an environment. Also helps us recognize scenes and objects and also manipulating objects in our hands
Agnosia
-Lack of recognition of familiar objects: Can be from lack of being able to perceive what the object is (form, color etc.) or Lack of being able to recognize its’ meaning
- Requires both hemispheres of brain working together
1.Visual processing (non-lateralized)
2.Perceptual processing (right hemisphere)
3. Semantic processing (left hemisphere)
- Normal object recognition requires:
1. Visually be able to process the image
2. Be able to remember previous images that were the same or similar
3. Associate the current visual image meaning to previous images
Agnosia: Prosopagnosia
- Prosopagnosia is a deficit that causes the inability to recognize a face that is known to them.
- Individual can:Recognize facial structures: Identify male vs. female, Identify different races
- Ranges in severity, some individuals can’t recognize themselves in the mirror
Apraxia
- “A cognitive motor disorder that involves the loss or impaired ability to program motor systems to perform purposeful skilled movements.”
- *This is in the absence of any deficit to the motor, sensation and coordination systems.
- Exact cause of apraxia is unknown but it is thought that it is a problem with the complex skill of motor planning in either one of two areas: Planning, Execution
Apaxia Cause
- Conceptual system: Ie. knowing use of tools (action and function),
- Sequence of actions
- Perceptual issues: Ie. If the object required is not nearby, individual might use something that looks similar (ex. Pouring cream meant for coffee into orange juice)
- Difficulty interpreting situation or command (not from aphasia)
Ideomotor Apraxia
- Inability to imitate gestures or perform an intended action on command
- Patient knows what to do but can’t manage to do it
- Often still can perform old habitual tasks
- Less severe than ideational apraxia
Ideation Apraxia
- Caused by the deficit in conception of a task vs. execution
- Considered more severe
- Don’t have knowledge of what tools are used for
- Difficult to diagnose because 90% of patients also have aphasia or dementia
Dressing Apraxia
-Difficulty dressing oneself: Puts pants on backwards, upside down or inside out
- Caused more by issues related to body scheme rather than sequence of tasks
- Caused by impaired visuospatial issues
Acalculia
- “The inability to perform calculation tasks resulting from cerebral pathology.”
- Can be as severe as difficulty with any task involving numbers (ie. dialing phone)
- Even performance of very simple math equations such as 5-2= require multiple areas of the brain: Parietal, Frontal, Thalamus
- Math requires multiple brain processes including: Arithmetic facts, Arithmetic procedures, Recognition of arithmetic signs
Treatment for Acalculia
- Restorative Approach: Identify all areas where numbers and math processes are impaired and begin to work step by step to relearn these
- Adaptive/Compensatory Approach: Provide tools: calculator, If can’t use a telephone, have numbers on speedial, Have assistance for required IADLs