1.DEFINITION
Utilization behavior is a type of neurobehavioral disorder that involves patients grasping or using objects that are within reach or in the field of vision and starting the 'appropriate' behavior associated with it at an 'inappropriate' time. While objects may be used correctly, the behavior occurs in a context that is inappropriate.
The patients who display utilization behavior tend to reach out and begin to automatically use objects in the visual field of their environment. This may not seem incorrect but the difference in action to a person without UB is that the "object-appropriate" action taken is performed at the inappropriate time. While objects may be used correctly, the behavior occurs in a context that is inappropriate. For example, a patient in a doctor's office sees a toothbrush and will involuntarily start brushing his teeth. This demonstrates the appropriate action (brushing) at the inappropriate time (office).
Encyclopedia of Clinical Neuropsychology, 2011
Utilization behavior: clinical manifestations and neurological mechanisms, 2001
2.BACKGROUND
The tactile, visuotactile and visual presentation of objects compels the patients to grasp and use them. This behavior was obtained with miscellaneous utilitarian objects. For the patients, the presentation of objects implies the order to grasp and use them. It is proposed that the balance between the subject's dependence on and independence from the outside world is disturbed. With frontal lesions, the inhibitory function of the frontal lobes on the parietal lobes is suppressed. The result is a release of the activities of the parietal lobes so that the subject becomes dependent on visual and tactile stimulation from the outside world.
‘Utilization Behavior’ and its relation to lesions of the frontal lobes, F. Lhermitte, 1983
3.EPIDEMIOLOGY
The incidence and prevalence of utilization behavior is unknown.
4.SYMPTOMS
What is surprising about the UB is that the patient does not detect any discrepancy between his actions and his intentions, so he will claim that “he wanted to do that.” Patients with utilization behavior feel they are functioning normally and do not believe that their actions are anything out of the ordinary. Sufferers are unable to resist grasping or using an object placed in front of them, regardless of the context or environment.
It is not known what triggers them to exhibit UB with certain external stimuli and not others.
A disorder related to UB consists of the feeling that a body part is separate from the rest of the body and has a mind of its own. The patient does not recognize the limb as one that he/she owns and believes it to be a foreign object which he cannot control. This set of symptoms is related to Alien Hand Syndrome (AHS), a neurological disorder in which the subject does not acknowledge ownership of a limb when visual cues are lacking. AHS can involve damage to the anterior cingulate gyrus, the medial prefrontal cortex and the anterior corpus callosum when a patient has frontal AHS.
Utilization behavior: clinical manifestations and neurological mechanisms., 2001
5.NEUROLOGICAL BASES
The UB has been associated with lesions of different brain areas as if with various (and often very different) conditions, from neurodegenerative diseases to neuropsychiatric disorders.
The pathophysiology of UB appears to involve dysfunction in structures of the mesial frontal lobe and fronto - striatal pathways. In particular, these structures appear to be involved:
- SMA
- cingulate gyrus
- both basal ganglia thalamocortical circuits
UB is hypothesized to result from an imbalance between a medial motor system, which is responsible for internally generated control of movement and goal-directed action, and a lateral motor system, which facilitates monitoring and responding to external environmental stimuli. The medial pathway is thought to function upstream from and to exert control over the lateral pathway.
An important role is played by prefrontal and associative areas that match the motor commands with personal goals before the transduction by the motor cortices into movements.
The original model by Denny-Brown and Chambers, that has been then formalized by Mesulam in 1986, is the basis of Lhermitte interpretation. The model assumes the existence of two competitive biological orientations (tropisms), an approaching/excitatory one, dependent upon more posterior cerebral systems, and a withdrawal/inhibitory one, based upon anterior systems. These two systems were hypothesized to act in opposing, but complementary fashions in the coordination of movement at all levels of the neuroaxis. The hypothesis is that UB is given by impairment of this last mechanism, leading to a non-inhibition of the “chain of behaviors”.
According to the model, exploratory movements like visual tracking, grasping, and groping are triggered by sensory input processed in cortical and subcortical sensory areas. However, if the response is unnecessary, maladaptive, or inappropriate to the larger external context, or to the organism’s internally generated intentions and motor goals, such responses are inhibited before they are produced. This inhibition involves frontal, and particularly mesial frontal structures and their subcortical striatal and thalamic connections.
Withdrawal/avoidance/neglect behaviors are thought to result from lesions involving the posterior temporal and parietal lobes and involve failures to orient or respond to sensory inputs or abnormal movements away from sensory input.
Another accepted model is that proposed by Goldberg. The author hypothesizes two different systems: medial and lateral. This distinction is based upon the differentiation of internally- and externally-guided actions. According to his model, the mesial portion of the frontal lobes, including the SMA, will dominate when the task is internally guided, whereas the lateral portion of the premotor area becomes more involved when the behavior depends on or is primarily made in response to external stimuli or cues. This area is activated when people are asked to perform movements under the guidance of visual, auditory, or somatosensory feedback.
The cingulate gyrus, which receives input from the striatum and basal ganglia, projects to the SMA, which projects to the motor cortex, creating the potential to both facilitate and inhibit motor responses. With damage to the mesial system, including the SMA or cingulate gyrus or both, there may be both a reduction of normal internally generated, willed movement, manifest as akinesia, motor neglect, motor impersistence or all of these, and a release of unintended reflexive movements in the form of UB.
Goldberg’s model suggests that widespread activation of the cortical mantle provides a contextual basis for action. This activity converges on the striatum, passes through the ventral thalamus, and on to the SMA. This transformation from context to intention to act is modulated by the limbic system both within the basal ganglia and via projections to the SMA from the cingulated cortex, which itself receives projections from the anterior and medial thalamus. The SMA, which participates earlier than the primary motor cortex in the translation of motive to intention to act, projects to both the primary motor cortex and corticospinal fibers. The goal is to select a context-appropriate behavioral schema in accordance with internal goals and states. At the same time, sensory information from parietal cortex, lateral thalamus, and direct cerebellar inputs converge on the lateral premotor cortex, triggering motor responses that serve to monitor and explore environmental events.
Utilization Behavior: What Is Known and What Has to Be Known?, 2014
Utilization Behavior: Clinical Manifestations and Neurological Mechanisms, 2001
6.DIAGNOSIS
To date, three eliciting methods have been proposed to verify the presence of UB.
The first method, devised by Lhermitte himself, simply consists in putting an object in the hands of the subject and then observing his behavior (assuming that “healthy” would ask something like what should I do? or why do you give me this?). The resulting utilization behavior is called “induced UB”.
In the second method, the UB is elicited by positioning an object on the desk, suddenly and not in front of the patient, in a way that should not let him think that he has to use it. If the object captures patient's attention and utilization occurs, this is the case of “incidental UB.”
The third (and most recent) method is called “verbal generation procedure” and is devised in the framework of the “embodied cognition” hypothesis. Patients are asked to describe the actions involved in various activities of daily living (such as doing the dishes or writing a letter) in the presence of objects within their reach and field of vision. The actions to be verbalized were sometimes linked to the objects (condition VG2), and sometimes were not (condition VG1).
During the VG procedure, the examiner first explained what the subjects had to do and told them explicitly not to touch or use the objects. He said: “I am going to ask you to describe the actions that make up some everyday activities. I am going to place some objects in front of you, but you must not touch or use them. This instruction has also been written on this sheet of paper. Do you have any questions?” The piece of A4 paper with the instruction was displayed near to the patient. The examiner checked that the patient understood the directions and placed a cardboard shield across the table and placed the relevant objects out of sight of the patient. The shield was removed so that the objects were within the patient’s field of vision, and the patient then started to verbalize the relevant script. At the end of each exercise, the examiner changed the objects for the verbalization of the next script behind the shield. At the end of the procedure, the examiner asked the patient to recall the instruction that he had given at the beginning.
Using these three methods, doctors can test the patient's response, communication and motor skills but the only way to fully diagnose this disorder is to do a scan of the brain to see if the frontal lobe has been damaged. This can be done with the following scan types:
- CT Scan (X-ray computed tomography)
- MRI (Magnetic resonance imaging)
- PET (Positron emission tomography)
- SPECT (Single photon emission computed tomography)
Utilization Behavior: What Is Known and What Has to Be Known?, 2014
Utilization Behavior: Clinical Manifestations and Neurological Mechanisms, 2001
7.TREATMENT
Although no specific cure has been found for UB, steps can be taken to reduce its symptoms and severity. If UB is a symptom of an underlying disease or disorder, treatment of the disease itself can reduce the severity of UB and may eradicate it completely.
Upon treatment, the UB was resolved due to 60–70% shrinkage of the anterior lobe hypodensities.
Concerning general frontal lobe damage, rehabilitation is known to help a patient function with their disorder.
8.DIFFERENTIAL DIAGNOSIS
From the clinical standpoint, it is quite important to distinguish the UB from other kinds of pathological manipulation and grasping.
- UB and ADS (Action Disorganization Syndrome)
Both the syndromes involve actions and movements. However, the patient with UB is able to perform all the necessary steps to accomplish or execute a complex action. (for example, he is able to hang a picture on the wall).
On the contrary, a patient suffering from ADS is unable to execute a complex behavior showing a wide variety of errors, from “place substitution” (e.g., while preparing the coffee, the patient takes a spoon of butter instead of the coffee powder) to “step omission” while performing a step-by-step action (e.g., putting the pot without the water on the gas).
In brief, when a patient is unable to accomplish routine actions, most likely he is not showing UB.
- UB and Alien Hand Syndrome
The difference between UB and Alien Hand Syndrome (AHS), sometimes called anarchic hand, is more subtle, but relatively easy to detect. The UB is not associated with rejection of the agency by the patient; in other words, he is somewhat “syntonic” with his own actions. On the contrary, the patient with AHS is aware of his disorder, often reporting: “the arm is moving by itself.” It is noteworthy that an “anarchic hand” may also perform complex movements, and it is not rare to observe the so-called “inter manual conflict,” in which the alien hand is opposing the movement performed by the other hand. An interesting contribution for understanding the difference between UB and AHS is the study by Pacherie, which compares two approaches to the agentive self-awareness: the holistic narrator-based approach and the atomistic comparator-based approach.
In brief, when the patient is telling you he did not want to perform the movements just executed, UB can be excluded.
- UB and Grasping Reflex
The grasping reflex (GR, or palmar grasping reflex) as defined by Denny-Brown and Chambers in 1958 is the automatic tendency of the infant (or the patient) to grasp an object. The reflex can be elicited by putting examiner's hand (or just one finger) in the hand of the patient. Sometimes, the patient is unable to release the grip (forced grasping). In literature we can find as synonym of GR also other terms, like Manual Grasping Behavior or Magnetic Apraxia.
Thus, a patient unable to stop in manipulating an object (e.g., during a Lhermitte elicitation procedure), in spite of the reinforcement by the examiner, is probably not affected by UB, although the cooccurrence of the UB and GR cannot be excluded.
- UB and Manual Groping Behavior
Another reflex sometimes present in patients with frontal lobe damage is the Manual Groping Behavior (also referred to as groping reflex). In this case, the patient seems to be magnetically attracted by an object, and this phenomenon may happen for both manually and visually processed stimuli.
The groping reflex is characterized by the fact that “the behaviors do not appear to be volitional or purposeful and are very repetitive and stereotypic.” This feature contributes to differentiating groping behavior from UB, in which movements are goal directed.
Utilization Behavior: What Is Known and What Has to Be Known?, 2014
