basic understanding & terminologies
WHAT IS COGNITION?
Cognition can be defined as the mental processes involved in acquiring and processing information that are necessary for everyday living. it is simply the process of thinking.
COGNITIVE DOMAINS
domains and processes include orientation , perception, attention , memory and learning, judgment, reasoning, language, and executive functions.
PRIMARY COGNITIVE PROCESSES
orientation- Orientation refers to the awareness of self in relation to person, place, time, and circumstance (Sohlberg & Mateer, 1989)
Attention- defined by William James as “the taking possession by the mind, in a clear and vivid form, of one out of what seem several simultaneously present objects or trains of thought”. Regions of the brain involved in regulating attention are the cingulate cortex, limbic system, prefrontal cortices, and sensorimotor regions.
Types of attention
- sustained attention- maintaining attention over time during continuous activity (Sohlberg & Mateer, 2001) like peeling onions or cutting vegetables.
- selective attention- when an individual concentrates on one set of stimuli while ignoring competing stimuli (Sohlberg & Mateer, 2001) for ex:- studying while TV is on, learner ignores the sound of TV to pay attention to studies.
- alternating attention- occurs as one flexibly shifts attention between multiple operations (Sohlberg & Mateer, 2001) for example:- answering the door bell & coming back to continue making the bedsheet.
- Divided attention- Ability to respond to two tasks simultaneously (Sohlberg & Mateer, 2001) for example:-walking & talking.
MEMORY
Memory broadly refers to information storage and retrieval(Lezak, 1995). To understand further, we first need to talk about human information processing model proposed by Shiffrin & Atkinson.
Sensory Registers- Information from the environment is briefly (milliseconds) held in registers specific to the human senses (Lezak, 1995). This registration stage has been called the intake valve for determining what data from the environment are ultimately stored. This phase is influenced by acuity of the senses (such as hearing and vision), affective set, and perception.
Short-Term Memory/Working Memory- STM reflects “faculties of the
human mind that can hold a limited amount of information
in a very accessible state temporarily” . The term working memory pertains to the attention-related processes that are involved in managing incoming information and manipulating stored information for planning and problem solving (Cowan, 2008). Unlike long-term memory, which is thought to have an infinite capacity, working memory has a restricted holding capacity of seven plus or minus two chunks of information. working memory is the foundation of concentration and problem solving.
LONG TERM MEMORY- When we remember information (an event that occurred an hour ago or a year ago), we have located and retrieved data from long-term memory and are holding it for conscious attention and thought in limited-capacity working memory. Long-term memory is thought to consist of two subsystems, explicit (or declarative) memory and implicit(or nondeclarative) memory.
Declarative memory pertains to factual information and includes episodic memory (knowledge of personal information and events such as what you ate for breakfast) and semantic memory (knowledge of facts about the world such as that horses are big and ants are small).
Implicit or non-declarative memory differs from explicit memory because it does not involve conscious awareness of learning. This includes procedural memory, which pertains to knowing how to do things, it allows us to learn and perform skilled motor actions.
EXECUTIVE FUNCTIONS
they consist of those capacities that enable a person to engage successfully in independent, purposive, self serving behaviour. They consist of 4 overlapping components: volition, planning, purposive action & effective performance.
a) volition is the capacity to determine what one needs & wants to do. it also encompasses a future realization of one’s needs & wants. It includes self awareness, awareness of environment & social awareness.
b) planning is the identification & organization of steps & elements. it includes weighting alternatives & making choices.
c) purposive action includes productivity & self regulation which involves initiation, switching & stopping complex sequences to realize a goal.
d) effective performance is the capacity for quality control including the ability to self- monitor & correct one’s behaviour.
PERCEPTION
the process or result of becoming aware of objects, relationships, and events by means of the senses, which includes such activities as recognizing, observing, and discriminating. These activities enable organisms to organize and interpret the stimuli received into meaningful knowledge and to act in a coordinated manner.
Acc to Zoltan, perceptual dysfunction can be divided into body scheme disorders, visual perceptual disorders and agnosias.
BODY SCHEME DISORDERS
body image- defined as a visual & mental image of one’s body that includes feelings about one’s body.
body scheme- refers to a postural model of the body, including the relationship of body parts to each other & to the environment.
Specific impairments of body image are unilateral neglect, somatoagnosia, right-left discrimination, finger agnosia & anosognosia.
UNILATERAL NEGLECT
it is the inability to register & integrate stimuli & perceptions from one side of the body & environment which is not due to sensory loss. It is also referred to as unilateral spatial neglect, hemi-inattention, hemineglect, etc. it is a frequent clinical finding, neglect following right cerebral infarction has been reported in 12%–95% of patients.
ANOSOGNOSIA
it is defined as a lack of awareness or denial of a paretic extremity as belonging to the person. The pathogenesis remains unclear although region of supramarginal gyrus has been proposed.
SOMATOAGNOSIA
it is an impairment in body scheme or a lack of awareness of the body parts to self or others, it is also known as autopagnosia. Lesion site is thought to be parietal lobe & is commonly seen with right hemiplegia.
RIGHT-LEFT DISCRIMINATION
it is the inability to identify the right & left sides of one’s own body or of the examiner. Lesion site is seen in the parietal lobe.
FINGER AGNOSIA
it is defined as the inability to identify the fingers of one,s own hands or of the examiner. it may be the result of a parietal lobe lesion. it correlates highly with poor dexterity in tasks that require movements of individual fingers.
Visual perception disorders/ spatial relation disorders
It encompasses a constellation of impairments that have in common a difficulty in perceiving the relationship between self and 2 or more objects.
Figure ground discrimination
It is the inability to visually distinguish a figure from the background in which it is embedded for ex: white shirt on a white towel, spoon in the array of utensils, black buttons on a black shirt. Parieto-occipital lesions of the right hemisphere commonly produces this type of disorder.
Form discrimination
It is the inability to attend to subtle differences in form & shape, patient may confuse a toothbrush with a pen, letter b with d, etc. parieto occipital temporal areas of the brain are associated with this function.
Spatial relations
It is the inability to perceive the relationship of one object in space to another object or to oneself. The patient might find it difficult to place the cutlery, plate or glass in the proper position. The patient may face difficulty in perceiving hands of a clock and thereby fail to tell the correct time of the day.
Position in space impairment
It is the inability to perceive and to interpret concepts such as up,down,in front of, behind, etc. patient may be asked to place an object in different positions like inside a drawer, top of the drawer, in a box, beside a box or may be asked to place a spoon inside spoon holder or behind the holder and asked to describe the location. Lesion area is commonly dominant perinatal lobe.
Topographical disorientation
Inability in understanding or locating directions or a geographical location. Patient may not be able to find the way from his home to the local shop which he has visited numerous times before. Bilateral parietal lesions can produce this impairment.
Depth perception
Inability to accurately judge direction, depth or distance. Patient may have difficulty in navigating stairs, pouring water in a cup, sitting in a chair. It may be associated with visual association areas.
Vertical disorientation
Refers to a distorted perception of what is vertical. Displacement of vertical position can contribute to disturbance of motor performance. Lesion site is in the non dominant parietal lobe. Patient may be unable to hold a pencil in a vertical position.
AGNOSIA
It is the inability to recognise or make sense of incoming information despite intact sensory capacities.
It’s of various types: tactile, auditory or visual agnosia(most common) also note that a person with visual agnosia may have intact visual system, likewise for other sensory modalities. Specific types of visual agnosia include simultanagnosia(inability to perceive a visual stimulus as a whole) prosopagnosia(inability to recognise familiar faces) & Color agnosia(inability to recognise colors; not the same as color blindness)
APRAXIA
It is an impairment of voluntary skilled learner movements, characterised by an inability to perform purposeful movements which cannot be accounted for by inadequate strength, loss of coordination, loss of sensation, abnormal tone, etc. The 2 main forms of apraxia most commonly talked about in literature are ideomotor and ideational.
IDEOMOTOR: it is a breakdown between concept and performance. There is a disconnection between the idea of the movement and its motor execution. Patients often perseverate I.e they repeat an activity or a segment of a task over and over. They have difficulty in performing activities with too many steps on command. The patient may not be able to comb on command however if the patient is presented with a comb he/she/they might start combing.
IDEATIONAL: it is a failure in the conceptualisation of the task. Inability to perform activity, either automatically or on command. In the same example as above, patient may not start combing even after presented with a comb or on command.
Thank you for reading. In further blogs, we will talk about assessment and treatment of cognitive and perceptual dysfunction. For queries/collab, mail us at rupsher2720@gmail.com or DM us on our Instagram page(TheraspOT).
REFERENCES
- Cognitive and perceptual rehabilitation: optimising function by Glen Gilen
- Occupational therapy in physical dysfunction by Catherine. A Trombly
