1. Name of Institution
1
Amity Institute of Psychology &
Allied Sciences
MA, Clinical Psychology Semester 3
Subject-Basics of Neuropsychology
Faculty- Dr. Anganabha Baruah
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Structures in Parietal Lobe
• Postcentral gyrus: This region is the brain's
primary somatosensory cortex, and maps
sensory information onto what is known as a
sensory homonculus. Some researchers also refer
to this region as Brodmann area 3.
• Posterior parietal (Association) cortex: This
region is thought to play a vital role in coordinating
movement and spatial reasoning. It also plays a role
in attention, particularly attention driven by new
stimuli, such as when an animal jumps into the road
while you are driving.
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• Superior parietal lobule: This region helps you
determine your own orientation in space, as well as
the orientation of other objects. It also receives
significant input from the hand, suggesting that it helps
coordinate fine motor skills and sensory input from the
hands.
• Inferior parietal lobule: Sometimes called
Gerschwind's territory, this region aids in assessing
facial expressions for emotional content. Some
research suggests it plays a role in other functions,
including language processing, basic mathematical
operations, and even body image. It contains a
number of sub-regions, including the angular and
supramarginal gyrus.
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SUPERIOR PARIETAL LOBULE
The superior parietal lobule forms the association cortex of the
parietal lobe, and plays an important role in planned
movements, spatial reasoning and attention. The intraparietal
sulcus can be further divided into a lateral, medial, ventral and
anterior area. The lateral area is responsible for our eye
movements in response to a stimulus in space. The medial
area helps us to determine how far and where we need to reach
in relation to our nose. The ventral area is an area that
receives a number of sensory modalities; these include
auditory, visual, vestibular and somatosensory information.
Finally, the anterior area enables us to interpret the size, shape
and position of objects we are about to grasp. The anterior and
ventral areas work together to enable visual motor coordination
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Inferior Parietal Lobule
• Most neuroscientists also include
regions of the inferior parietal lobule,
particularly the supramarginal
gyrus (Brodmann area 40) and
the angular gyrus (Brodmann area 39) in
Wernicke’s area. The supramarginal
gyrus forms the auditory area of speech,
while the angular gyrus, the visual area
of speech.
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• The Parietal lobes
control calculation and language on
the dominant side, and the sensory
visuospatial processing on the non-
dominant hemisphere side.
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Functions of Parietal Lobes
• Distinguishing between two points, even without visual input.
• Localizing touch: When you touch any object with any part of
your body, your parietal lobe enables you to feel the sensation
at the site of the touch and not, say, in your brain or all over
your body.
• Integrating sensory information from most regions of the body.
• Visuospatial navigation and reasoning: When you read a map,
follow directions, or prevent yourself from tripping over an
unexpected obstacle, your parietal lobe is involved. The parietal
lobe is also vital for proprioception—the ability to determine
where your body is in space, including in relationship to itself.
For instance, touching your finger to your nose without the
assistance of a mirror is a function of the parietal lobe.
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• Some visual functions, in conjunction with the occipital lobe.
• Assessing numerical relationships, including the number of
objects you see.
• Assessing size, shape, and orientation in space of both visible
stimuli and objects you remember encountering.
• Mapping the visual world: a number of recent studies suggest
that specific regions in the parietal lobe serve as maps to the
visual world.
• Coordinating hand, arm, and eye motions.
• Processing language.
• Coordinating attention.
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Damage
• Difficulty with drawing objects
• Difficulty in distinguishing left from right
• Spatial disorientation and navigation difficulties
• Problems with reading (Alexia)
• Inability to locate the words for writing (Agraphia)
• Difficulty with doing mathematics (Dyscalculia)
• Lack of awareness of certain body parts and/or
surrounding space (Neglect)
• Inability to focus visual attention
• Difficulty with motor planning and complex
movements(Apraxia)
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The occipital lobe
• is the visual processing center of the mammalian brain containing
most of the anatomical region of the visual cortex.
• The primary visual cortex is Brodmann area 17, commonly
called V1 (visual one).
• Human V1 is located on the medial side of the occipital lobe
within the calcarine sulcus;
• the full extent of V1 often continues onto the posterior pole of
the occipital lobe. V1 is often also called striate cortex because it
can be identified by a large stripe of myelin, the Stria of Gennari.
22. Name of Institution
Extrastriate regions
• Visually driven regions outside V1 are called
extrastriate cortex.
• There are many extrastriate regions, and these are
specialized for different visual tasks, such as
visuospatial processing, color discrimination, and
motion perception.
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Primary Visual Cortex (V1)
• The primary visual cortex also known as
V1, Brodmann area 17, or the striate
cortex, is located on either side of the
calcarine sulcus on the medial surface of
the occipital lobe and extends into both
the cuneus and the lingual gyrus. It
functions to receive special sensory
input from the eyes via the optic
radiations, and is, therefore, responsible
for integration and perception of visual
information. 23
24. Name of Institution
• Visual association cortex
• The visual association cortex constitutes the
remaining regions of the occipital lobe and is
also known as the extrastriate visual cortex.
This region functions to interpret visual
images.Located within the visual association
cortex of the occipital lobe are the second,
third and fourth visual areas.
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25. Name of Institution
• Second visual area
• The second visual area, also known as
the secondary visual cortex, V2, or the
prestriate cortex, occupies much of Brodmann
area 18 and in some cases 19. The secondary
visual cortex surrounds the primary visual
cortex and receives information from it. The
information from the primary visual cortex is
sent to the secondary visual cortex , before
being passed to the third and fourth visual
areas to finally reach the inferior temporal
cortex. The secondary visual area is important
for color, motion, and depth perception. 25
26. Name of Institution
• Third visual area
• The third visual area, or V3, lies adjacent to the
anterior aspect of V2 and is also located within
Brodmann area 18. This visual area communicates
directly with the secondary visual cortex and is
functionally important in the visual processing of
motion.
• Fourth visual area
• Visual area four, V4, is located anterior to V3 within
Brodmann area 19. It communicates and receives
information from the secondary visual cortex. The
function of visual area four is to interpret colors,
orientation, form and movement. 26
27. Name of Institution
Connections of the Visual Cortex
Connections
-Primary Visual Cortex (V1)
-Input from LGN
-Output to all other levels
-Secondary Visual Cortex (V2)
Output to all other levels
-After V2
•Output to the parietal
lobe - Dorsal Stream
•Output to the inferior temporal
lobe - Ventral
Stream
•Output to the superior
temporal sulcus (STS) - STS
Stream
• DorsalStream
– Visual Guidance of Movements
• Ventral Stream
– Object Perception
• STS
– Visuospatial functions (bio movement
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Functions
• A significant functional aspect of the occipital lobe is that it
contains the primary visual cortex.
• Retinal sensors convey stimuli through the optic tracts to the
lateral geniculate bodies, where optic radiations continue to the
visual cortex.
• Each visual cortex receives raw sensory information from
the outside half of the retina on the same side of the head and
from the inside half of the retina on the other side of the head.
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Function
V1 - function like mailboxes: segregating info to other areas.,
receives primary visual impressions Color/Form/Motion/Size and
illumination.
V2, V3, V3A, V4, V5- Visual association areas- Recognition and
identification of objects, storage of visual memories, it functions
in more complex visual recognition and perception,
revisualization, visual association and spatial orientation.
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•Contour analysis and binocular vision
are two functions of the visual cortex, and such processing is a
function of both its horizontal and its vertical organization.
•The cells within the striate cortex are activated only by input
from the LGN, although other cortical areas have input into the
striate cortex.
•The striate cortex communicates with the superior colliculus
and the frontal eye fields.
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Clinical Effects of Occipital Lobe Lesions
• Visual Field Defects
• Cortical blindness
• Visual Anosognosia
• Visual Illusions
• Visual hallucinations
• Visual Agnosias
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Visual field defects
• The most familiar clinical abnormality resulting from a lesion of one
occipital lobe, is a contralateral homonymous hemianopia,.
• Extensive destruction abolishes all vision in the corresponding half
of each visual field.
• With a neoplastic lesion that eventually involves the entire striate region,
the field defect may extend from the periphery toward the center, and
loss of color vision (hemiachromatopsia) often precedes loss of black and
white.
• Destruction of only part of the striate cortex on one side yields
characteristic field defects that accurately indicate the loci of the lesion.
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Cortical Blindness
• With bilateral lesions of the occipital lobes (destruction of area 17 of
both hemispheres), there is a loss of sight that can be conceptualized
as bilateral hemianopia.
• The degree of blindness may be equivalent to that which follows
severing of the optic nerves.
• The pupillary light reflexes are preserved because they depend
upon visual fibers that terminate in the midbrain, but reflex closure of
the eyelids to threat or bright light may be preserved
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• No changes are detectable in the retinas.
• The eyes are still able to move through a full range and, if there is
macular sparing as there usually is with vascular lesions, optokinetic
nystagmus can be elicited
• Visual imagination and visual imagery in dreams are preserved.
• With rare exceptions, no cortical potentials can be evoked in the
occipital lobes by light flashes or pattern changes (visual evoked
response), and the alpha rhythm is lost in the electroencephalogram
35. Name of Institution
The usual cause of
cortical blindness
• is occlusion of the posterior cerebral arteries (most often embolic) or the
equivalent, occlusion of the distal basilar artery.
• Macular sparing may leave the patient with an island of barely serviceable
central vision.
• The infarct may also involve the mediotemporal regions or thalami, which share
the posterior cerebral artery supply, with a resulting Korsakoff amnesic defect
and a variety of other neurologic deficits referable to the high midbrain and
diencephalon (drowsiness, akinetic mutism etc… )
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Visual Anosognosia (Anton
Syndrome )
• The main characteristic of this disorder is the denial of blindness by a
patient who obviously cannot see.
• The patient acts as though he could see, and in attempting to walk,
collides with objects, even to the point of injury.
• The lesions in cases of negation of blindness extend beyond the
striate cortex to involve the visual association areas.
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Visual Illusions
(Metamorphopsias)
• These may present as distortions of form, size, movement, or color like deformation
of the image, change in size, illusion of movement, or a combination of all three.
• Illusions of these types have been reported with lesions confined to the
occipital lobes but are more frequently caused by shared occipitoparietal or
occipitotemporal lesions;
• The right hemisphere appears to be involved more often than the left.
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Visual
Hallucinations
• These phenomena may be elementary or complex, and both
types have sensory as well as cognitive aspects.
• Elementary (or unformed) hallucinations include flashes of
light, colors, luminous points, stars, multiple lights (like candles),
and geometric forms (circles, squares, and hexagons).
• They may be stationary or moving (zigzag, oscillations,
vibrations, or pulsations).
•Complex hallucinations include objects, persons, or animals and
infrequently, more complete scenes that are indicative of lesions
in the visual association areas or their connections with the
temporal lobes.
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Color vision defects
• Two types of color vision deficit are associated with
occipital lesions.
• First, a complete loss of color vision, or
achromatopsia, may occur either ipsilaterally or in
one visual hemifield with lesions that involve
portions of the visual association cortex (Brodmann
areas 18 and 19).
• Second, patients with pure alexia and lesions of
the left occipital lobe fail to name colors, although
their color matching and other aspects of color
perception are normal.
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• Patients often confabulate an incorrect color name when asked
what color an object is.
• This deficit can be called color agnosia, in the sense that a
normally perceived color cannot be properly recognized.
• Although this deficit has been termed color anomia, these
patients can usually name the colors of familiar objects such as
a school bus or the inside of a watermelon.
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Visual Object
Agnosia
• Visual object agnosia is the quintessential visual agnosia: the patient
fails to recognize objects by sight, with preserved ability to recognize
them through touch or hearing in the absence of impaired primary
visual perception or dementia
• In 1890, Lissauer distinguished two subtypes of visual object agnosia:
apperceptive visual object agnosia, referring to the synthesis of
elementary perceptual elements into a unified image, and
associative visual object agnosia, in which the meaning of a perceived
stimulus is
appreciated by recall of previous visual experiences.
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Apperceptive
Visual Agnosia
• The first type, apperceptive visual agnosia, is difficult to separate from
impaired perception or partial cortical blindness.
• Any failure of object recognition in which relatively basic visual functions
(acuity, color, motion) are preserved is apperceptive.
• Patients with apperceptive visual agnosia can pick out features of an object
correctly (e.g., lines, angles, colors, movement), but they fail to appreciate the
whole object
• Warrington and Rudge (1995) pointed to the right parietoccipital cortex for its
importance in visual processing of objects, and they found this area critical to
apperceptive visual agnosia.
43. Name of Institution
•Apperceptive visual agnosia related to bilateral occipital lesions a
“pseudoagnosic syndrome” associated with visual processing defects, as
compared to true visual agnosias, in
which the right parietal cortex is deficient in identifying and recognizing visual
objects.
•Recent evidence of the functions of specific cortical areas has included the
specialization of the medial occipital cortex for appreciation of color and
texture,whereas the lateral occipital cortex is more involved with shape
perception.
•Deficits in these specific visual functions can be seen in patients with visual
object agnosia
44. Name of Institution
• apperceptive visual agnosia usually occurs in patients with bilateral
occipital lesions.
• It may represent a stage in recovery from complete cortical blindness.
• Deficits in recognition of visual objects may be especially apparent with
recognition of degraded
images, such as drawings rather than actual objects.
• Apperceptive visual agnosia can also be part of dementing syndromes
45. Name of Institution
Associative visual agnosia
• It is defect in the association of the object with past experience and memory .
The inability to recognize an object despite an apparent perception of the
object
is associative agnosia.
• Some patients can copy or match drawings of objects they cannot name,
thus excluding a primary defect of visual perception.
• Aphasia is excluded because the patient can identify the same object presented
in the tactile or auditory modality
• occurs with bilateral occopitotemoral junction lessions.
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prosopagnosia
• Patients with facial agnosia cannot recognize any
previously known faces, including their own as seen in a mirror or
photograph.
• First, patients who cannot match pictures of faces must have defective
face processing,or apperceptive prosopagnosia, whereas those who can
match faces but simply fail to recognize familiar examples(either friends
and relatives or famous personages) have associative prosopagnosia
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Benton Face Recognition
• History: “facial agnosia”/ prosopagnosia
• Purpose: Measures visualoperceptual discrimination of unfamiliar faces
(not recognition/memory)
• Associated with right hemisphere: parietal, occipitoparietal and occipitotemporal
• 3 parts:
– Match identical front view
– Match front view with ¾ view
– Match front view with various lighting conditions
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In clinical studies
• prosopagnosia may occur either as an isolated deficit or as
part of a more general visual agnosia for objects and colors.
Faces are likely the most complex and individualized visual
displays to recognize, but some patients with visual object
agnosia can recognize faces, suggesting that there may be a
specific brain area devoted to facial recognition.
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Optic Aphasia
• The syndrome of optic aphasia, or optic anomia, is intermediate
• between agnosias and aphasias.
• The patient with optic aphasia cannot name objects presented visually
but can demonstrate recognition of the objects by pantomiming or describing
their use.
• The preserved recognition of the objects distinguishes optic aphasia from
associative visual agnosia.
• Like visual agnosics, patients with optic aphasia can name objects presented in
the auditory or tactile modalities, distinguishingthem from anomic aphasics.
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In optic aphasia
• information about the object must reach parts of the cortex involved in
recognition, perhaps in the right hemisphere, but the information is not
available to the language cortex for naming.
• Patients with optic aphasia may confabulate incorrect names when
asked to name an object they clearly recognize,just as the patient with
color agnosia confabulates incorrect color names.
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Visuospatial Agnosia
•Among this variety of disorders of spatial perception and orientation,
one disruptive form is topographical disorientation—the inability to find
one’s way around familiar environments such as one’s neighborhood.
•People with this deficit seem unable to recognize landmarks that
would indicate the appropriate direction in which to travel
•Most people with topographical disorientation have other visual deficits,
especially defects in facial recognition.
• Critical area for this disorder lies in the right medial
occipitotemporal region, including the fusiform and lingual gyri.
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Epilepsy and occipital lobes
• Occipital lobe seizures are triggered by a flash, or a visual image that
contains multiple colors. These are called flicker stimulation (usually
through TV) these seizures are referred to as photo-sensitivity
seizures. Patients having experienced occipital seizures described their
seizure as seeing bright colors, and having severe blurred vision
(vomiting was also apparent in some patients).
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Occipital seizures
• are triggered mainly during the day, through television, video games or any
flicker stimulatory system.
• Occipital seizures originate from an epileptic focus confined within the
occipital lobes. They may be spontaneous or triggered by external visual stimuli.
Occipital lobe epilepsies are etiologically idiopathic, symptomatic, or
cryptogenic.
• Symptomatic occipital seizures can start at any age, as well as any stage after or
during the course of the underlying causative disorder.
• Idiopathic occipital epilepsy usually starts in childhood.
• Occipital epilepsies account for approximately 5% to 10% of all epilepsies.
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• Receptive aphasia
• Wernicke’s area (Brodmann area 22) lies in the superior
temporal gyrus and overlaps the parieto-temporal junction.
This region is responsible for our understanding of speech.
Damage to this region will result in a receptive aphasia,
which is a fluent form of aphasia. The patient will present
with ‘word salad’ i.e. they will be able to form words, but the
words will not be in any comprehensible order or syntax. The
homologous area of the right cortex, is responsible for our
interpretation of body language, and making sense of
ambiguous words. Damage to Wernicke’s area may not
always result in a receptive aphasia. If the surrounding
cortex is intact, and the right corresponding area is intact,
there symptoms may be minimal.
55
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• Bálint’s syndrome
• This syndrome is usually associated with large bilateral lesions,
resulting in deficits in visual attention, as well as motor function.
Symptoms include:
• simultanagnosia (the patient isn’t able to interpret to see the
whole visual field)
• optic ataxia (the patient isn’t able to move their hands in
relation to their visual input)
• optic apraxia (an inability to fixate the eyes).
• As Bálint’s syndrome is a rare disease. Sudden severe
hypotension, which impacts the watershed areas between the
parietal and occipital lobes, is most common cause of the
bilateral ischaemia. Due to the range of symptoms and
manifestations, the condition is often mistaken for blindness
related to other disorders. 56
57. Name of Institution
• Parietal lobe stroke
• Ischaemic strokes are commonly the result of atheroschlerotic
emboli. The middle cerebral artery is the largest branch of the
internal carotid artery, and a direct continuation of the artery. It
is therefore the commonest location of ischaemic strokes. The
middle cerebral artery supplies the lateral surface of the
parietal lobe (as well as the superior temporal lobe), which is
the location of the upper limb and face on the primary
somatosensory cortex. Therefore, strokes impacting the
middle cerebral artery result in sensory loss of these areas,
with sparing of the lower limbs. Motor function of the same
areas may also result, as the primary motor cortex is just
anterior to the primary somatosensory cortex, and is also
supplied in part by the middle cerebral artery.
57
58. Name of Institution
• Hemi spatial neglect is a phenomenon that usually follows
damage to the non-dominant parietal lobes (usually the right),
usually following a stroke. The patient is still able to see both
sides of their visual fields in both eyes, but is not able to
interpret the sensory information sent to the brain from one
half of the visual field. If a stroke occurs in the right parietal
lobe, the patient will ignore the left visual field. If a stroke
occurs in the left parietal lobe, the ability of the patient to
solve mathematical problems, as well as reading and writing
would be impaired.
• The symptom of optic ataxia results in issues with the
patient reaching for objects in the contralateral visual field to
the affected parietal lobe. Amorphosynthesis is a condition
where the patient is unaware of somatic sensations from one
side of the body, and is a possible result of parietal lobe
stroke.
58
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• If the left lobe is affected, agnosia (a loss of general
perception) results. A lesion of the right parietal lobe
causes issues with the person’s interpretation of the
left side of their visual field, as well as their personal
space.
• Apraxia is a disorder of motor control, that usually
results from damage to the left parietal lobe.
• Damage to Baum’s loop results in a contralateral
lower quadrantanopia, or a ‘pie in the floor’ visual
deficit. A lesion of Meyer’s loop results in a
contralateral upper quadrantanopia, or ‘pie in the sky’
visual deficit.
59
60. Name of Institution
• Gerstmann’s syndrome
• This syndrome is related to damage to the inferior parietal
lobule in the dominant hemisphere of the brain (usually the
left), and is associated with right-left confusion and presents
characteristic symptoms, including:
• agraphia (difficulty in writing)
• acalculia (difficulty with math)
• aphasia (language disorders)
• agnosia (difficulty to perceive objects
• These symptoms vary in severity between patients. When
the supramarginal and/or angular gyri (parts of the inferior
parietal lobule) are impacted, the patient’s ability to interpret
written or oral language may be impacted. 60
61. Name of Institution
Tests for
calculations
Components – Rote tables (add, multiply, etc)
Recognition of signs (+ , - , * )
Basic arithmetic(carrying, borrowing) Spatial
alignment of written calculations
• Verbal rote examples : what is 4 plus 6 ?
• Verbal complex examples : what is 21 * 5 ?
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Tests for right –
left confusion
Identification on self
ex : show your left foot.
Crossed commands on self
ex : with your right hand touch your left ear
Identification on examiner
ex : point my right elbow
Crossed commands on examiner
ex : with your left hand point my right foot.
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Tests for finger agnosia
• Inability to name , point or recognize fingers on
oneself or others.
1.Non verbal finger recognition :
with pt eyes closed, touch one of his fingers.
Ask him to touch the same finger of examiner, with
eyes open.
2.Identifying named fingers on examiner’s hand :
examiner places hand in some irregular
position and asks pt – “ point to my middle finger”
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IDEOMOTOR APRAXIA (“how to do”)
•Most common type of apraxia
i.Buccofacial apraxia ( blowing a match )
ii.Limb apraxia ( flip a coin , comb hair )
iii.Whole body apraxia ( stand like boxer )
•Commands to be alternated b/w right and left
limbs
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IDEATIONAL APRAXIA(“what to do”)
• Disturbance of complex motor planning of a higher
order .
• Pt able to do individual tasks, but cannot integrate
them as a whole.
• ‘Conceptual apraxia’ – there is apparent inability to
recognise the use of objects (object agnosia).
ex: pt attempts to light a candle by striking it on matchbox
66. Name of Institution
Praxis testing (done in an order)
1. Observe the actions – shaving ,dressing,eating.
2. Carry out familiar acts – blow a kiss, wave gudbye.
3. Imitate the examiner (‘do this after me’)
4. How to use objects (pantomime)
simple acts – hammer nail, comb hair .
complex acts – light and smoke cigar; open soda
bottle, pour in glass and drink.
5. Demonstrate use of actual items
(both limbs and orofacial commands to be asked)
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Drawings to command :
1. draw a clock with 10:20 time
2. draw a 2D figure - daisy in a pot
3. draw a house – in way you can see two sides
and the roof.
Block designs
Lt. sided lesions – simplification of complex diagrams
Rt. sided lesions – rotation of diagrams .
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DRESSING APRAXIA
•Not a true apraxia.
•Combination of spatial disorientation and
visuospatial inattention.
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Tests for visual disorders
• Visual field testing
• Visual neglect :
- casual observation of pt’s behaviour.
- drawings made by the pt.
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Tests for geographic
disorientation
• Geographic orientation is function of parietal lobe and its
multimodal association area.
• Combination of processes – spatial
orientation, right-left orientation ,visual perception and its
memory.
1.History from relatives :
Does he become lost in work?
Does he have difficulty in orienting to new environment?
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2. Localizing places in maps :
Adequate literacy level and historical knowledge is necessary.
ex : to locate cities or states on maps.
3. Ability to orient self in hospital :
By observing the pt’s capacity to find their bed, ward and
bathroom.