MOTIVATION AND EMOTION

Motivation. Motivation describes the intensity and persistence in working toward a goal. Motivation requires emotional responsivity, executive functions, and “auto-activation” collaborating in a motivation-action-reward loop involving prefrontal cortex (dorsolateral; anterior cingulate) and basal ganglia (dorsal caudate, internal globus pallidus, substantial nigra, ventral striatum, ventral pallidum). Apathy and abulia are disorders of diminished motivation and important manifestation of brain disease. Apathy (“without passion”) is prominently decreased emotional responsivity with a lack of emotional expression or interest in activities. Clinical conditions associated with apathy include anosodiaphoria (lack of concern for an acknowledged disorder), anosognosia (lack of knowledge for a disorder), alexithymia (inability to identify one’s emotions), and “stuporous” catatonia (unresponsive, mute, immobile with inappropriate or prolonged postures or body positions into which they are placed [“cataplexy”]). In contrast to apathy, abulia (“without will”) is a primary loss of initiation from executive dysfunction and autoactivation (self-initiation). Clinically, examiners have difficulty distinguishing abulia from apathy. Compared with apathy, abulia appears more severe, results from frontal cognitive impairment rather than primary emotional hyporesponsivity, and melds into akinetic mutism with absent spontaneous movements or speech beyond occasional words or short phrases (see Chapter 7 ).

Emotion. Many definitions of emotion view it as a type of motivation aimed at promoting adaptive behavior. Emotional experiences are subjective “feelings” associated with somatic-autonomic nervous system arousal. There are much data showing that the somatic-autonomic activity for emotional experiences vary greatly. This, along with the cognitive appraisal or interpretation of emotions, challenges the view that specific emotions originate from specific brain regions. Nevertheless, there is evidence for the reconstitution of somatic states in ventromedial prefrontal cortex when exposed to certain types of experiences. There is also some support for both right hemisphere dominance for emotions and the valence theory attributing negative emotional tendencies to the right hemisphere and positive emotional tendencies to the left. Two important components of emotion that can be disturbed in patients are mood and affect. Mood is the patient’s subjective feelings, whereas affect is the outward expression of emotion, such as withdrawn expression, poor eye contact, and tearfulness. Mood and affect are not necessarily congruent and can be dissociated as in pseudobulbar palsy in which excessive affect may not reflect the quality and extent of the underlying mood.

SOCIAL BEHAVIOR

A number of brain regions participate in social behavior and can be disturbed from brain disease. Social propriety and interactions can be profoundly altered with mesial frontolimbic lesions, as exemplified by John Harlow’s description of Phineas Gage, perhaps neurology’s most famous patient ( Fig. 14.1 ). Gage’s behavior was dramatically changed after an accident propelled an iron rod through his brain damaging his ventromedial prefrontal areas. Subsequently, he became, in the words of John Harlow, “…fitful, irreverent, indulging at times in the grossest profanity (which was not previously his custom), manifesting but little deference for his fellows, impatient of restraint or advice when it conflicts with his desires….[with] the animal passions of a strong man…” Gage’s behavioral changes illustrate how the mesial frontal lobes (ventromedial, orbitofrontal) are particularly involved in human social behavior. The ventromedial prefrontal cortex attributes meaning to social phenomena and related areas determine the socioemotional significance of percepts (anterior insulae, anterior cingulate cortex, amygdala, anterior temporal cortex). Many neurological illnesses have prominently disturbed social tact and manners, disinhibition, and inability to comply with social norms consequent to lesions or disease in these regions ( Table 14.1 ).

White Matter Tracts Affected by Ventromedial Prefrontal Cortex Damage (Left worse than Right) in Phineas Gage. Modeling the path of the tamping iron through the Gage skull and its effects on white matter structure.

(A) The skull of Phineas Gage on display at the Warren Anatomical Museum at Harvard Medical School. (B) CT image volumes were reconstructed, spatially aligned, and manual segmentation of the individual pieces of bone dislodged by the tamping iron (rod), top of the cranium, and mandible was performed. Surface meshes for each individual element of the skull were created. Based upon observations from previous examinations of the skull as well as upon the dimensions of the iron itself, fiducial constraint landmarks were digitally imposed and a set of possible rod trajectories were cast through the skull. This figure shows the set of possible rod trajectory centroids which satisfied each of the anatomical constraints. The trajectory nearest the mean trajectory was considered the true path of the rod and was used in all subsequent calculations. Additionally, voxels comprising the interior boundary and volume of the cranial vault were manually extracted and saved as a digital edocast of Mr. Gage’s brain cavity. (C) A rendering of the Gage skull with the best fit rod trajectory and example fiber pathways in the left hemisphere intersected by the rod. Graph theoretical metrics for assessing brain global network integration, segregation, and efficiency were computed across each subject and averaged to emasure the changes to topological, geometrical, and wiring cost properties. (D) A view of the interior of the Gage skull showing the extent of fiber pathways intersected by the tamping iron in a sample subject (i.e. one having minimal spatial deformation to the Gage skull). The intersection and density of WM fibers between all possible pairs of GM parcellations was recorded, as was average fiber length and average fractional anisotrophy (FA) integrated over each fiber. (From Van Horn JD, Irimia A, Torgerson CM, Chambers MC, Kikinis R, Toga AW. Mapping connectivity Damage in the Case of Phineas Gage. Plos One 7(5); 2012.)

The examiner assesses social cognition not only from observation of social behavior but also through tests of Theory of Mind, empathy, and social perception. Theory of Mind is the ability to represent the thoughts, beliefs, attitudes, and feelings of others. It involves the ventromedial prefrontal cortex, amygdala and anterior temporal pole, posterior superior temporal sulcus, precuneus, and the right temporoparietal junction. There are different subtypes of Theory of Mind, including cognitive understanding, affective understanding, and first- or second-order levels. With regard to empathy, there is no universally accepted definition. Most agree that empathy is the ability to identify with the emotional experience of (“feeling as”) others in a prosocial way. It involves an evaluation of the experience of others, which leads to the creation of a model in one’s mind of another’s feelings. The experience of empathy facilitates sympathy (“feeling for”) for others and prosocial behavior (responding compassionately). An aspect of “cognitive empathy” is perspective taking, which involves the dorsal mid anterior cingulate cortex, adjacent dorsomedial frontal cortex, and ventromedial prefrontal cortex. An aspect of “emotional empathy” is affect sharing, which involves the anterior insula and inferior frontal gyrus (right frontal subgenual and right temporo-limbic). Finally, social perception for faces, body, and other signals of emotion are an additional critical part of navigating the social world. Most of these overlaps with perception, as described in Chapter 10 , with special emphasis on the ability to recognize facial emotions.

PSYCHOPHYSIOLOGICAL BEHAVIORS (INCLUDING AGGRESSION)

Broadly defined, psychophysiological behaviors involve the hypothalamus and related areas, which regulate the sleep-wake cycle, the sexual drive, hunger and satiety, thirst and drinking, and aggressive behavior. Inappropriate or increased sexual behavior may be manifestations of brain disease, either from primary hypersexuality or from sexual disinhibition. In primary hypersexuality, there are recurrent and intense sexual fantasies, urges, and risky behaviors, often associated with repetitive but unsuccessful efforts to reduce or control these sexual symptoms. Primary hypersexuality has occurred with strokes and surgical resections for epilepsy, tumors, or right temporal variant frontotemporal dementia from temporal-amygdalar damage and a release of sexual arousal. Far more commonly, inappropriate sexual behavior results from sexual disinhibition as part of a frontally mediated general disinhibition. These patients react impulsively and opportunistically to tempting environmental situations involving sexual or other objects of interest, without necessarily following-through or consummating their sexual behavior.

Changes in dietary and eating behavior from brain disease include a spectrum from alterations of dietary preferences to the placement of nonfood or inedible items in their mouths. Basic food intake is under hypothalamic control, with a lateral region controlling feeding and a medial region controlling satiety; however, complex changes in eating behavior are more commonly associated with right frontal and temporal lobe damage rather than with hypothalamic lesions. Excessive eating (hyperphagia) is a significant feature, not only of neurological conditions, such as behavioral variant frontotemporal dementia, the Klein–Levin syndrome, and the human Klüver–Bucy syndrome, but also of developmental disorders, such as the Prader–Willi syndrome. Patients with frontotemporal dementia syndromes may have cravings for sweets or carbohydrates or obsessions for particular foods. In addition, disease in the orbitofrontal region may impair the ability to refrain from taking food or to respond to feelings of satiety.

Aggression is someone’s action that intentionally delivers something unpleasant, either psychological or physical, to another. Violence is an extreme form of aggression that involves physical action. There are two major types of aggression: 1) reactive or affective aggression, which is an emotional, often explosive, response to a perceived threat or provocation; and 2) instrumental or predatory aggression, which is controlled (organized), purposeful (premeditated), and may be used to achieve an antisocial goal. The hypothalamus and periaqueductal gray of the midbrain (connected to amygdala and prefrontal cortex) control the expression of both behavioral and autonomic components of aggression. Reactive aggressive is associated with abnormalities in the hypothalamic–pituitary–adrenal axis, as well as in serotonin and catecholamine neurotransmitters. Reduced control from the prefrontal cortex, in particular its medial and orbitofrontal portions, is associated with instrumental as well as reactive aggression. In addition, investigators have reported smaller and more hypofunctional amygdalae among chronic violent offenders.

CONTENT (SPEECH AND LANGUAGE, THOUGHT, BEHAVIOR)

Speech and Language Content. “Content” refers to subject matter expressed in speech and language, thought, and behavior. Speech and language changes reflecting disturbed content may particularly occur from frontal disease. These changes include disorganized speech, incoherence, illogicality, poverty of speech content, and the related tendencies to go off-track in their conversation or responses, such as tangentiality, circumstantiality, and frank derailment. In tangentiality, patients go from one related topic to another, each further afield from the original topic of conversation, whereas in circumstantiality, patients talk around the original topic of conversation while focusing on unnecessary but related details or facts. These patients may additionally have palilalia and echolalia, neologisms and paraphasias, word approximations, clanging and rhyming, and cataphasia or verbigeration (morbid repetition of words, phrases, or sentences).

Thought Content. Thought process describe a patient’s form of thinking and expressed ideas or “themes,” including false reports, such as delusions and confabulations. Delusions are false beliefs that are fixed (held with certainty), incorrigible (held against all proof to the contrary), and implausible (impossibility or falsity of content). Common themes include persecution, grandiosity, control, jealousy, guilt or sin, and content-specific delusions such as the delusion of theft in patients with Alzheimer’s disease. Confabulations are false reports that are made without a conscious effort to deceive for the purpose of creating a coherent self-narrative. Most are provoked or “momentary” confabulations elicited specifically in response to questions that probe memory in patients with memory impairment, such as Korsakoff syndrome. Frontal lobe variants of confabulation, fantastic confabulations and fantastic thinking, are grandiose or impossible elaborations of internally generated ideas associated with vivid imagination and wish fulfillment. Confabulations differ from delusions in being more often provoked, inconsistent, often redirectable, and generally plausible, unless of the fantastic subtype.

Content of Behavior. Semipurposeful movements that appear goal-related reflect a type of disturbed content. These include stereotypies, compulsive-like behavior, and punding. Stereotypies are usually repetitive, rhythmic, often bilateral movements with a fixed pattern (e.g., tapping, hand posturing, head movements) and regular frequency that can usually be stopped by distraction. With stereotypies in autism or frontotemporal dementia, there appears to be striatal-thalamo-frontal neural circuit dysfunction leading to activation imbalance. In addition to traditional compulsions, similarly complex compulsive-like behaviors may also occur from frontostriatal disease. These compulsive-like behaviors are repetitive, variable, and ritualistic acts, such as repetitive trips to the bathroom or repetitive oral sounds or motor movements. Compulsive-like behaviors are an impulse-control disorder possibly from specific involvement of the right frontolimbic-striatal system rather than true compulsions, which are negatively driven by the need to relieve anxiety. Diogenes syndrome is a type of compulsive-like behavior characterized by the combination of extreme self-neglect and excessive collecting with clutter and squalor in patients with frontally predominant dementia. Punding is another related but distinct disorder characterized by even more complex, repetitive, excessive, and seemingly goal-oriented activity. First seen in amphetamine and cocaine addicts, it also occurs among patients with Parkinson disease who are receiving dopaminergic medications. The behaviors are useless, even if goal-oriented, and appear to be impulse control disturbances not driven by anxiety or the need for pleasure or gratification.

ALTERED PERCEPTIONS

Hallucinations and Illusions . Hallucinations are abnormal perceptions that occur in the absence of external sensory input, and illusions are altered perceptions that are based on a genuine sensory input. Hallucinations and illusions may involve any modality, including visual, auditory, olfactory, gustatory, or tactile. Visual hallucinations, more than auditory hallucinations, suggest neurological disease such as dementia with Lewy bodies, rather than a primary psychotic disorder. Visual hallucinations may be a “release” due to primary visual or other impairment, rapid eye movement or dream state breakthrough, or excitatory, as from seizure activity. In elderly persons, release visual hallucinations may occur in association with cognitive impairment and ophthalmological disease, that is, visual hallucinations of Bonnet, and they are often formed, animate (living), and lilliputian (small) figures. Breakthrough hallucinations may occur during transitional periods of waking (hypnopompic) or going (hypnogogic) to sleep. Illusions, in contrast to hallucinations, are due to errors in “binding” between competing basic elements of perception and require elicitation by specific perceptual stimuli. Pareidolias are visual illusions involving ambiguous forms being perceived as meaningful objects, which occur with dementia with Lewy bodies. Additionally, delusional misidentifications include Capgras (known person replaced by imposter), Fregoli (unfamiliar persons are a certain person in disguise), intermetamorphosis (people swapped identities but not appearance), and doppelgänger (a patient’s double is carrying out independent action).

The general concept of body identity disorders includes a large number of conditions. These disorders refer to distortions on how people see themselves and their bodies and are associated with a visuospatial map of the body, more specifically a body-centered reference system located in the right superior parietal region. Patients with right parietal damage can have disturbances of the integrity of their body image, such as left-sided attentional neglect, asomatognosia or the loss of awareness of parts of one’s body, anosognosia or loss of awareness or denial of illness, alexisomia or inability to read one’s body states, anosodiaphoria or loss of concern for illness, somatoparaphrenia or the denial of ownership of a limb or one half of the body, misoplegia or hatred of the left side, and even xenomelia or the desire for the amputation of a limb. In addition, derealization and depersonalization are part of the spectrum of these disturbed body perceptions. Derealization is a feeling that the environment is unreal, strange, or alien, and depersonalization is the same feeling about oneself. These conditions should not be confused with somatotopagnosia and autotopagnosia, which are left parietal origin errors in localization on one’s or another’s body (see Chapter 12 ). Finally, phantom limbs are a phenomenon of persistent experiencing the presence, or pain from, an amputated limb, possibly from remapping of deafferented neurons unto adjacent cortex.

MOTIVATION AND EMOTION

Motivation. The examiner investigates for apathy and abulia using a checklist of critical items on history and on behavioral observation. First, there should be collateral history as to whether the patient has ceased engaging in his or her usual activities. Second, the examiner determines what the patient actually does during the day, and whether the patient performs activities of daily living, from dressing to toileting, without prompting. On examination, support for a disorder of motivation include the following:

• 1.
  

  Inertia, or the absence of spontaneous verbal and motor behavior;

  
  
• 2.
  

  Detachment, or the absence of engagement with others and surroundings;

  
  
• 3.
  

  Lack of affect, or the presence of flat or apathetic expressions;

  
  
• 4.
  

  Impaired response initiation, or the presence of minimal, brief, or slow responses to command or to events;

  
  
• 5.
  

  Impersistence, or the need for significant prompting to continue any activity.

One of the most widely used measurement scales for apathy is the Apathy Evaluation Scale and its variations, which takes approximately 10 to 20 minutes to complete. It is included here for reference and as a guide for evaluating these patients ( Table 14.2 ).

TABLE 14.2

Apathy Evaluation Scale, Clinician Version (AES-C)

Name:		Date:
Rater:
Rate each item based on an interview of the subject. The interview should begin with a description of the subject’s interest, activities, and daily routine. Base your ratings on both verbal and nonverbal information. Ratings should be based on the past 4 weeks. For each item ratings should be judged:
Not at All Characteristic 1	Slightly Characteristic 1	Somewhat Characteristic 3	A Lot Characteristic 4
_____1.	S/he is interested in things.		+C Q
_____2.	S/he gets things done during the day.		+B Q
_____3.	Getting things started on his/her own is important to her/him.		+C SE
_____4.	S/he is interested in having new experiences.		+C Q
_____5.	S/he is interested in learning new things.		+C Q
_____6.	S/he puts little effort into anything.		–B
_____7.	S/he approaches life with intensity.		+E
_____8.	Seeing a job through to the end is important to her/him.		+C SE
_____9.	He/she spends time doing things that interest her/him.		+B
_____10.	Someone has to tell her/him what to do each day.		–B
_____11.	S/he is less concerned about his/her problems than she/he should be.		–C
_____12.	S/he has friends.		+B Q
_____13.	Getting together with friends is important to her/him.		+C SE
_____14.	When something good happens, he/she gets excited.		+E
_____15.	S/he has an accurate understanding of her/his problems.		+O
_____16.	Getting things done during the day is important to her/him.		+C SE
_____17.	S/he has initiative.		+O
_____18.	S/he has motivation.		+O

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