Liepmann was the first to actually conduct tests on these patients in his laboratory. These tests are known as multiple-object tasks or MOT. Each task requires the patient to use more than one object; the researcher describes a task to the patient and asks them to execute that task as described. Liepmann gave the patients all the necessary articles, such as a candle and a matchbox, which were placed before the patient. He then observed the patients to see how they interacted with each object. In the case of the matchbox, one patient brought the whole box up next to the wick, instead of just one match. Another opened the box and withdrew a match, then brought it to the wick unlighted. Still another patient struck the candle against the striking surface on the matchbox. Thus Liepmann was able to witness the discontinuity of the patients' actions with respect to everyday objects and to categorize the errors that the patients made, namely: mislocation of actions, object misuse, omissions, perplexity, and sequence errors.

It should be noted that, even though afflicted persons are unable to correctly perform simple tasks using multiple items as provided, they "are" able to accurately identify the objects involved in simple tasks. For example, they are able to match a given sequence of photographs with the correct label, such as: the process of making coffee, buttering bread, or preparing tea. These patients are also able to successfully identify objects when a researcher verbally describes the function of the tool. Another test involves matching the appropriate object with its function. Finally, the fact that patients can identify the actions of a given tool from a sequence of photographs, shows that they completely understand object usage.

The deficit is therefore not that patients lack the knowledge of how to use an object; they fully understand the function of each tool. Rather, the problem lies in that, when they attempt to interact with the tools (in a multiple-object task) in order to execute those functions, that execution is flawed.

Ideational apraxia (IA) is a neurological disorder which explains the loss of ability to conceptualize, plan, and execute the complex sequences of motor actions involved in the use of tools or otherwise interacting with objects in everyday life. Ideational apraxia is a condition in which an individual is unable to plan movements related to interaction with objects, because he has lost the perception of the object's purpose. Characteristics of this disorder include a disturbance in the concept of the sequential organization of voluntary actions. The patient appears to have lost the knowledge or thought of what an object represents. This disorder was first seen 100 years ago by Doctor Arnold Pick, who described a patient who appeared to have lost their ability to use objects. The patient would make errors such as combing their hair with the wrong side of the comb or placing a pistol in his mouth. From that point on, several other

researchers and doctors have stumbled upon this unique disorder. IA has been described under several names such as, agnosia of utilization, conceptual apraxia or loss of knowledge about the use of tools, or semantic amnesia of tool usage. The term apraxia was first created by Steinthal in 1871 and was then applied by Gogol, Kusmaul, Star, and Pick to patients who failed to pantomime the use of tools. It was not until the 1900s, when Liepmann refined the definition, that it specifically described disorders that involved motor planning, rather than disturbances in the patient’s visual perception, language, or symbolism.

Constructional apraxia is characterized by an inability or difficulty to build, assemble, or draw objects. Apraxia is a neurological disorder in which people are unable to perform tasks or movements even though they understand the task, are willing to complete it, and have the physical ability to perform the movements. Constructional apraxia may be caused by lesions in the parietal lobe following stroke or it may serve as an indicator for Alzheimer's disease.

Ideomotor apraxia (IMA) impinges on one's ability to carry out common, familiar actions on command, such as waving goodbye. Persons with IMA exhibit a loss of ability to carry out motor movements, and may show errors in how they hold and move the tool in attempting the correct function.

One of the defining symptoms of ideomotor apraxia is the inability to pantomime tool use. As an example, if a normal individual were handed a comb and instructed to pretend to brush his hair, he would grasp the comb properly and pass it through his hair. If this were repeated in a patient with ideomotor apraxia, the patient may move the comb in big circles around his head, hold it upside-down, or perhaps try and brush his teeth with it. The error may also be temporal in nature, such as brushing exceedingly slowly. The other characteristic symptom of ideomotor apraxia is the inability to imitate hand gestures, meaningless or meaningful, on request; a meaningless hand gesture is something like having someone make a ninety-degree angle with his thumb and placing it under his nose, with his hand in the plane of his face. This gesture has no meaning attached to it. In contrast, a meaningful gesture is something like saluting or waving goodbye. An important distinction here is that all of the above refer to actions that are consciously and voluntarily initiated. That is to say that a person is specifically asked to either imitate what someone else is doing or is given verbal instructions, such as "wave goodbye." People suffering from ideomotor apraxia will know what they are supposed to do, e.g. they will know to wave goodbye and what their arm and hand should do to accomplish it, but will be unable to execute the motion correctly. This voluntary type of action is distinct from spontaneous actions. Ideomotor apraxia patients may still retain the ability to perform spontaneous motions; if someone they know leaves the room, for instance, they may be able to wave goodbye to that person, despite being unable to do so at request. The ability to perform this sort of spontaneous action is not always retained, however; some sufferers lose this capability, as well. The recognition of meaningful gestures, e.g. understanding what waving goodbye means when it is seen, seems to be unaffected by ideomotor apraxia. It has also been shown that ideomotor apraxia sufferers may have some deficits in general spontaneous movements. Apraxia patients appear to be unable to tap their fingers as quickly as a control group, with a lower maximum tapping rate correlated with more severe apraxia. It has also been demonstrated that apraxic patients are slower to point at a target light when they do not have sight of their hand as compared with healthy patients under the same conditions. The two groups did not differ when they could see their hands. The speed and accuracy of grasping objects also appears unaffected by ideomotor apraxia. Patients suffering from ideomotor apraxia appear to be much more reliant on visual input when conducting movements then nonapraxic individuals.

A key deficit in constructional apraxia patients is the inability to correctly copy or draw an image. There are qualitative differences between patients with left hemisphere damage, right hemisphere damage, and Alzheimer's Disease.

Optic ataxia is the inability to guide the hand toward an object using visual information where the inability cannot be explained by motor, somatosensory, visual field deficits or acuity deficits. Optic ataxia is seen in Bálint's syndrome where it is characterized by an impaired visual control of the direction of arm-reaching to a visual target, accompanied by defective hand orientation and grip formation. It is considered a specific visuomotor disorder, independent of visual space misperception.

Optic ataxia is also known as misreaching or dysmetria (), secondary to visual perceptual deficits. A patient with Bálint's syndrome likely has defective hand movements under visual guidance, despite normal limb strength. The patient is unable to grab an object while looking at the object, due to a discoordination of eye and hand movement. It is especially true with their contralesional hand.

Dysmetria refers to a lack of coordination of movement, typified by the undershoot or overshoot of intended position with the hand, arm, leg, or eye. It is sometimes described as an inability to judge distance or scale.

The reaching ability of the patient is also altered. It takes them longer to reach toward an object. Their ability to grasp an object is also impaired. The patient's performance is even more severely deteriorated when vision of either the hand or the target is prevented.

Bálint referred to this as "psychic paralysis of gaze"—the inability to voluntarily guide eye movements, changing to a new location of visual fixation. A major symptom of Oculomotor apraxia is that a person has no control over their eye movements, however, vertical eye movements are typically unaffected. For example, they often have difficulty moving their eyes in the desired direction. In other words, the saccades (rapid eye movements) are abnormal. Because of this, most patients with Oculomotor apraxia have to turn their heads in order to follow objects coming from their peripherals.

There are several types of apraxia including:

- Ideomotor apraxia: These patients have deficits in their ability to plan or complete motor actions that rely on semantic memory. They are able to explain how to perform an action, but unable to "imagine" or act out a movement such as "pretend to brush your teeth" or "pucker as though you bit into a sour lemon." However, when the ability to perform an action automatically when cued remains intact, this is known as automatic-voluntary dissociation. For example, they may not be able to pick up a phone when asked to do so, but can perform the action without thinking when the phone rings.

- Ideational/conceptual apraxia: Patients have an inability to conceptualize a task and impaired ability to complete multistep actions. Consists of an inability to select and carry out an appropriate motor program. For example, the patient may complete actions in incorrect orders, such as buttering bread before putting it in the toaster, or putting on shoes before putting on socks. There is also a loss of ability to voluntarily perform a learned task when given the necessary objects or tools. For instance, if given a screwdriver, the patient may try to write with it as if it were a pen, or try to comb his hair with a toothbrush.

- Buccofacial or orofacial apraxia: Non-verbal oral or buccofacial ideomotor apraxia describes difficulty carrying out movements of the face on demand. For example, an inability to lick one's lips or whistle when requested suggests an inability to carry out volitional movements of the tongue, cheeks, lips, pharynx, or larynx on command.

- Constructional apraxia: The inability to draw or construct simple configurations, such as intersecting shapes.

- Gait apraxia: The loss of ability to have normal function of the lower limbs such as walking. This is not due to loss of motor or sensory functions.

- Limb-kinetic apraxia: voluntary movements of extremities are impaired. For example, a person affected by limb apraxia may have difficulty waving hello.

- Oculomotor apraxia: Difficulty moving the eye, especially with saccade movements that direct the gaze to targets. This is one of the 3 major components of Balint's syndrome.

- Apraxia of speech (AOS): Difficulty planning and coordinating the movements necessary for speech (e.g. Potato=Totapo, Topato.) AOS can independently occur without issues in areas such as verbal comprehension, reading comprehension, writing, articulation or prosody.

Ideomotor Apraxia, often IMA, is a neurological disorder characterized by the inability to correctly imitate hand gestures and voluntarily mime tool use, e.g. pretend to brush one's hair. The ability to spontaneously use tools, such as brushing one's hair in the morning without being instructed to do so, may remain intact, but is often lost. The general concept of apraxia and the classification of ideomotor apraxia were developed in Germany in the late 19th and early 20th centuries by the work of Hugo Liepmann, Adolph Kussmaul, Arnold Pick, Paul Flechsig, Hermann Munk, Carl Nothnagel, Theodor Meynert, and linguist Heymann Steinthal, among others. Ideomotor apraxia was classified as "ideo-kinetic apraxia" by Liepmann due to the apparent dissociation of the idea of the action with its execution. The classifications of the various subtypes are not well defined at present, however, owing to issues of diagnosis and pathophysiology. Ideomotor apraxia is hypothesized to result from a disruption of the system that relates stored tool use and gesture information with the state of the body to produce the proper motor output. This system is thought to be related to the areas of the brain most often seen to be damaged when ideomotor apraxia is present: the left parietal lobe and the premotor cortex. Little can be done at present to reverse the motor deficit seen in ideomotor apraxia, although the extent of dysfunction it induces is not entirely clear.

Gerstmann syndrome is characterized by four primary symptoms:

1. Dysgraphia/agraphia: deficiency in the ability to write

2. Dyscalculia/acalculia: difficulty in learning or comprehending mathematics

3. Finger agnosia/anomia: inability to distinguish the fingers on the hand

4. Left-right disorientation

This disorder is often associated with brain lesions in the dominant (usually left) hemisphere including the angular and supramarginal gyri (Brodmann area 39 and 40 respectively) near the temporal and parietal lobe junction. There is significant debate in the scientific literature as to whether Gerstmann Syndrome truly represents a unified, theoretically motivated syndrome. Thus its diagnostic utility has been questioned by neurologists and neuropsychologists alike. The angular gyrus is generally involved in translating visual patterns of letter and words into meaningful information, such as is done while reading.

Given the previously stated signs and symptoms the following behaviors are often seen in people with aphasia as a result of attempted compensation for incurred speech and language deficits:

- Self-repairs: Further disruptions in fluent speech as a result of mis-attempts to repair erred speech production.

- Speech disfluencies: Include previously mentioned disfluencies including repetitions and prolongations at the phonemic, syllable and word level presenting in pathological/ severe levels of frequency.

- Struggle in non-fluent aphasias: A severe increase in expelled effort to speak after a life where talking and communicating was an ability that came so easily can cause visible frustration.

- Preserved and automatic language: A behavior in which some language or language sequences that were used so frequently, prior to onset, they still possess the ability to produce them with more ease than other language post onset.

Damage to the corpus callosum can give rise to "purposeful" actions in the sufferer's non-dominant hand (an individual who is left-hemisphere-dominant will experience the left hand becoming alien, and the right hand will turn alien in the person with right-hemisphere dominance).

In "the callosal variant", the patient's hand counteracts voluntary actions performed by the other, "good" hand. Two phenomena that are often found in patients with callosal alien hand are "agonistic dyspraxia" and "diagonistic dyspraxia".

Agonistic dyspraxia involves compulsive automatic execution of motor commands by one hand when the patient is asked to perform movements with the other hand. For example, when a patient with callosal damage was instructed to pull a chair forward, the affected hand would decisively and impulsively push the chair backwards.

Agonistic dyspraxia can thus be viewed as an involuntary competitive interaction between the two hands directed toward completion of a desired act in which the affected hand competes with the unaffected hand to complete a purposive act originally intended to be performed by the unaffected hand.

Diagonistic dyspraxia, on the other hand, involves a conflict between the desired act in which the unaffected hand has been engaged and the interfering action of the affected hand which works to oppose the purpose of the desired act intended to be performed by the unaffected hand. For instance, when Akelaitis's patients underwent surgery to the corpus callosum to reduce epileptic seizures, one patient's left alien hand would frequently interfere with the right hand. For instance, while trying to turn over to the next page with the right hand, his left hand would try to close the book.

In another case of callosal alien hand, the patient did not suffer from intermanual conflict between the hands but rather from a symptom characterized by involuntary mirror movements of the affected hand. When the patient was asked to perform movements with one hand, the other hand would involuntarily perform a mirror image movement which continued even when the involuntary movement was brought to the attention of the patient, and the patient was asked to restrain the mirrored movement. The patient suffered from a ruptured aneurysm near the anterior cerebral artery, which resulted in the right hand being mirrored by the left hand. The patient described the left hand as frequently interfering and taking over anything the patient tried to do with the right hand. For instance, when trying to grasp a glass of water with the right hand with a right side approach, the left hand would involuntary reach out and grasp hold of the glass through a left side approach.

More recently, Geschwind et al. described the case of a woman who suffered severe coronary heart disease. One week after undergoing coronary artery bypass grafting, she noticed that her left hand started to "live a life of its own". It would unbutton her gown, try to choke her while asleep and would automatically fight with the right hand to answer the phone. She had to physically restrain the affected hand with the right hand to prevent injury, a behavior which has been termed "self-restriction". The left hand also showed signs of severe ideomotor apraxia. It was able to mimic actions but only with the help of mirror movements executed by the right hand (enabling synkinesis). Using magnetic resonance imaging (MRI), Geschwind et al. found damage to the posterior half of the callosal body, sparing the anterior half and the splenium extending slightly into the white matter underlying the right cingulate cortex.

Apraxia is a motor disorder caused by damage to the brain (specifically the posterior parietal cortex), in which the individual has difficulty with the motor planning to perform tasks or movements when asked, provided that the request or command is understood and he/she is willing to perform the task. The nature of the brain damage determines the severity, and the absence of sensory loss or paralysis helps to explain the level of difficulty.

The term comes from the Greek ἀ- "a-" ("without") and πρᾶξις "praxis" ("action").

The syndrome rarely presents itself the same way in every patient. Some symptoms that occur may be:

- Constructional apraxia: difficulty in constructing: drawing, copying, designs, copying 3D models

- Topographical disorientation: difficulty finding one's way in the environment

- Optic ataxia: deficit in visually-guided reaching

- Ocular motor apraxia: inability to direct gaze, a breakdown (failure) in starting (initiating) fast eye movements

- Dressing apraxia: difficulty in dressing usually related to inability to orient clothing spatially, and to a disrupted awareness of body parts and the position of the body and its parts in relation to themselves and objects in the environment

- Right-left confusion: difficulty in distinguishing the difference between the directions left and right

People with aphasia may experience any of the following behaviors due to an acquired brain injury, although some of these symptoms may be due to related or concomitant problems such as dysarthria or apraxia and not primarily due to aphasia. Aphasia symptoms can vary based on the location of damage in the brain. Signs and symptoms may or may not be present in individuals with aphasia and may vary in severity and level of disruption to communication. Often those with aphasia will try to hide their inability to name objects by using words like "thing". So when asked to name a pencil they may say it is a thing used to write.

- Inability to comprehend language

- Inability to pronounce, not due to muscle paralysis or weakness

- Inability to speak spontaneously

- Inability to form words

- Inability to name objects (anomia)

- Poor enunciation

- Excessive creation and use of personal neologisms

- Inability to repeat a phrase

- Persistent repetition of one syllable, word, or phrase (stereotypies)

- Paraphasia (substituting letters, syllables or words)

- Agrammatism (inability to speak in a grammatically correct fashion)

- Dysprosody (alterations in inflexion, stress, and rhythm)

- Incomplete sentences

- Inability to read

- Inability to write

- Limited verbal output

- Difficulty in naming

- Speech disorder

- Speaking gibberish

- Inability to follow or understand simple requests

Peripheral agraphias occurs when there is damage to the various motor and visualization skills involved in writing.

- Apraxic agraphia is the impairment in written language production associated with disruption of the motor system. It results in distorted, slow, effortful, incomplete, and/or imprecise letter formation. Though written letters are often so poorly formed that they are almost illegible, the ability to spell aloud is often retained. This form of agraphia is caused specifically by a loss of specialized motor plans for the formation of letters and not by any dysfunction affecting the writing hand. Apraxic agraphia may present with or without ideomotor apraxia. Paralysis, chorea, Parkinson's disease (micrographia), and dystonia (writer's cramp) are motor disorders commonly associated with agraphia.

- Hysterical agraphia is the impairment in written language production caused by a conversion disorder.

- Reiterative agraphia is found in individuals who repeat letters, words, or phrases in written language production an abnormal number of times. Preservation, paragraphia, and echographia are examples of reiterative agraphia.

- Visuospatial agraphia is the impairment in written language production defined by a tendency to neglect one portion (often an entire side) of the writing page, slanting lines upward or downward, and abnormal spacing between letters, syllables, and words. The orientation and correct sequencing of the writing will also be impaired. Visuospatial agraphia is frequently associated with left hemispatial neglect, difficulty in building or assembling objects, and other spatial difficulties.

Unilateral injury to the medial aspect of the brain's frontal lobe can trigger reaching, grasping and other purposeful movements in the contralateral hand. With anteromedial frontal lobe injuries, these movements are often exploratory reaching movements in which external objects are frequently grasped and utilized functionally, without the simultaneous perception on the part of the patient that they are "in control" of these movements. Once an object has been acquired and is maintained in the grasp of this "frontal variant" form of alien hand, the patient often has difficulty with voluntarily releasing the object from grasp and can sometimes be seen to be peeling the fingers of the hand back off the grasped object using the opposite controlled hand to enable the release of the grasped object (also referred to as tonic grasping or the "instinctive grasp reaction"). Some (for example, the neurologist Derek Denny-Brown) have referred to this behavior as "magnetic apraxia"

Goldberg and Bloom described a woman who suffered a large cerebral infarction of the medial surface of the left frontal lobe in the territory of the left anterior cerebral artery which left her with the frontal variant of the alien hand involving the right hand. There were no signs of callosal disconnection nor was there evidence of any callosal damage. The patient displayed frequent grasp reflexes; her right hand would reach out and grab objects without releasing them. In regards to tonic grasping, the more the patient tried to let go of the object, the more the grip of the object tightened. With focused effort the patient was able to let go of the object, but if distracted, the behaviour would re-commence. The patient could also forcibly release the grasped object by peeling her fingers away from contact with the object using the intact left hand. Additionally, the hand would scratch at the patient's leg to the extent that an orthotic device was required to prevent injury. Another patient reported not only tonic grasping towards objects nearby, but the alien hand would take hold of the patient's penis and engage in public masturbation.

AOS and expressive aphasia (also known as Broca's aphasia) are commonly mistaken as the same disorder mainly because they often occur together in patients. Although both disorders present with symptoms such as a difficulty producing sounds due to damage in the language parts of the brain, they are not the same. The main difference between these disorders lies in the ability to comprehend spoken language; patients with apraxia are able to fully comprehend speech, while patients with aphasia are not always fully able to comprehend others' speech.

Conduction aphasia is another speech disorder that is similar to, but not the same as, apraxia of speech. Although patients who suffer from conduction aphasia have full comprehension of speech, as do AOS sufferers, there are differences between the two disorders. Patients with conduction aphasia are typically able to speak fluently, but they do not have the ability to repeat what they hear.

Similarly, dysarthria, another motor speech disorder, is characterized by difficulty articulating sounds. The difficulty in articulation does not occur due in planning the motor movement, as happens with AOS. Instead, dysarthria is caused by inability in or weakness of the muscles in the mouth, face, and respiratory system.

The warning signs of early speech delay are categorized into age related milestones, beginning at the age of 12 months and continuing through early adolescence.

At the age of 12 months, there is cause for concern if the child is not able to do the following:

- Using gestures such as waving good-bye and pointing at objects

- Practicing the use of several different consonant sounds

- Vocalizing or communicating needs

Between the ages of 15 and 18 months children are at a higher risk for speech delay if they are displaying the following:

- Not saying "momma" and "dada"

- Not reciprocating when told "no", "hello", and "bye"

- Does not have a one to three word vocabulary at 12 months and up to 15 words by 18 months

- Is unable to identify body parts

- Displaying difficulties imitating sounds and actions

- Shows preference to gestures over verbalization

Additional signs of speech delay after the age of 2 years and up to the age of 4 include the following:

- Inability to spontaneously produce words and phrases

- Inability to follow simple directions and commands

- Cannot make two word connections

- Lacks consonant sounds at the beginning or end of words

- Is difficult to understand by close family members

- Is not able to display the tasks of common household objects

- Is unable to form simple 2 to 3 word sentences

Phonological dyslexia is a reading disability that is a form of alexia (acquired dyslexia), resulting from brain injury, stroke, or progressive illness and that affects previously acquired reading abilities. The major distinguishing symptom of acquired phonological dyslexia is that a selective impairment of the ability to read pronounceable non-words occurs although the ability to read familiar words is not affected. It has also been found that the ability to read non-words can be improved if the non-words belong to a family of pseudohomophones.

The main clinical features are signature language progressive difficulties with speech production. There can be problems in different parts of the speech production system, hence patients can present with articulatory breakdown, phonemic breakdown (difficulties with sounds) and other problems. However, it is rare for patients to have just one of these problems and most people will present with more than one problem. Features include:

- Hesitant, effortful speech

- Speech 'apraxia'

- Stutter (including return of a childhood stutter)

- Anomia

- Phonemic paraphasia (sound errors in speech e.g. 'gat' for 'cat')

- Agrammatism (using the wrong tense or word order)

As the disease develops, speech quantity decreases and many patients will become mute.

Cognitive domains other than language are rarely affected early on. However, as the disease progresses other domains can be affected. Problems with writing, reading and speech comprehension can occur as can behavioural features similar to frontotemporal dementia.

Patients with autotopagnosia exhibit an inability to locate parts of their own body, the body of an examiner’s, or the parts of a representation of a human body. Deficiencies can be in localizing parts of a certain area of the body, or the entire body.

Some patients demonstrating the symptoms of autotopagnosia have a decreased ability to locate parts of other multipart object. Patients are considered to suffer from “pure” autotopagnosia, however, if their deficiency is specific to body part localization. Patients suffering from “pure” autotopagnosia often have no problems carrying out tasks involved in everyday life that require body part awareness. Patients have difficulty locating body parts when directly asked, but can carry out activities such as putting on pants without difficulty. Patients can describe the function and appearance of body parts, yet they are still unable to locate them.

Damage to the left parietal lobe can result in what is called Gerstmann syndrome. It can include right-left confusion, a difficulty with writing Agraphia and a difficulty with mathematics Acalculia. In addition, it can also produce language deficiencies Aphasia and an inability to recognize objects normally Agnosia.

Other related disorders include:

- Apraxia: an inability to perform skilled movements despite understanding of the movements and intact sensory and motor systems.

- Finger agnosia: An inability to name the fingers, move a specific finger upon being asked, and/or recognize which finger has been touched when an examiner touches one.

Simultanagnosia (or simultagnosia) is a rare neurological disorder characterized by the inability of an individual to perceive more than a single object at a time. This type of visual attention problem is one of three major components (the others being optic ataxia and optic apraxia) of Bálint's syndrome, an uncommon and incompletely understood variety of severe neuropsychological impairments involving space representation (visuospatial processing). The term "simultanagnosia" was first coined in 1924 by Wolpert to describe a condition where the affected individual could see individual details of a complex scene but failed to grasp the overall meaning of the image.

Simultanagnosia can be divided into two different categories: dorsal and ventral. Ventral occipito-temporal lesions cause a mild form of the disorder, while dorsal occipito-parietal lesions cause a more severe form of the disorder.

Agraphia or impairment in producing written language can occur in many ways and many forms because writing involves many cognitive processes (language processing, spelling, visual perception, visuospatial orientation for graphic symbols, motor planning, and motor control of handwriting).

Agraphia has two main subgroupings: central ("aphasic") agraphia and peripheral ("nonaphasic") agraphia. Central agraphias include , phonological, deep, and semantic agraphia. Peripheral agraphias include allographic, apraxic, motor execution, hemianoptic and afferent agraphia.