Chapter 13-15 Flashcards
flash-bulb memories
phenomenon whereby emotional memories often recalled more vividly after event
- memories recalled in a “photographic” form
- not actually more accurate than a normal memory, but feel more accurate
memory for emotions
information learned after-the-fact distort memory for emotions
emotion congruence
people remember information better if they learn it and recall it in the same (congruent) emotional state
- example: easier to conjure up a memory in which you were happy when you are currently happy
the limbic system
a complex set of brain structures that lies on both sides of the thalamus, right under the cerebrum
- collection of structures from the telencephalon, diencephalon, and mesencephalon
- supports a variety of functions, including emotion, motivation, and long-term memory
- seems to be primarily responsible for our emotional life and has a great deal to do with the formation of long-term episodic memories
the limbic lobe - Paul Broca (1878)
Broca called the limbic system the limbic lobe and suggested that the entire lobe might be concerned with the sense of smell
circle of papez
James Papez proposed the Papez circuit and that this network of brain structures worked together to mediate emotions
- hippocampus, hypothalamus, anterior thalamus, and cingulate gyrus
Paul MacLean
- expanded on Papez’s model
- termed it the limbic system
- added the amygdala to the limbic system
- claimed that the amygdala brings emotional attributes t hippocampal memory to bring about the formation of emotional memory
no universal agreement on the total list of structures that should be included in the term limbic system, but all authors would include…
cingulate and parahippocampal gyri, hippocampus, amygdala, septal nuclei, hypothalamus, midbrain reticular formation, olfactory areas
some neuroscientists, including Joseph LeDoux
suggest that the concept of a functionally unified limbic system should be abandoned as obsolete because it is grounded mainly in historical conceptos of brain anatomy that are no longer accepted as accurate
emotion
a collection of physiological changes in body and brain states triggered by a dedicated brain system that responds to a particular entity or event: some changes are non-perceptible to an external observer, some changes are perceptible to an external observer
feeling
the signals generated by these changes towards the brain itself produce changes that are mostly perceptible to the individual in whom they were enacted and provide the essential ingredients for what is ultimately perceived as a feeling
- what the individual senses or subjectively reports
emotion may be induced in two different ways
- primary induction
- secondary induction
primary induction of emotion
automatic
secondary induction of emotion
reflective/thoughtful
critical neural structures of emotion
- amygdala
- orbito/ventromedial prefrontal cortex
- insular cortex and cingulate cortex
primary inducers
stimuli that are innate or learned to be pleasurable or aversive; once they are encountered, they automatically, quickly, and obligatorily elicit an emotional response
- example: encountering a fear object (e..g, snake)
secondary inducers
entities generated by the recall of a personal or hypothetical emotional event (i.e., thoughts and memories about primary inducers), which when they are brought to mind (working memory), they slowly and gradually begin to elicit an emotional response
- example: memory of an emotional event, such as encountering or being bit by a snake, evokes fear
trigger structure for emotion from primary inducers
amygdala
trigger structure for emotion from secondary inducers
orbitofrontal cortex/ventromedial prefrontal cortex
neuroanatomy of emotions and feelings
three pathways:
emotionally competent stimulus (ex. snake) –> sensory systems –> amygdala –> visceral motor –> the viscera –> autonomic responses
emotionally competent stimulus (ex. snake) –> sensory systems –> ventromedial prefrontal cortex (anterior cingulate cortex and orbitofrontal cortex) –> orbitofrontal cortex –> visceral motor –> the viscera –> autonomic responses
the viscera –> visceral sensory –> insular cortex –> anterior cingulate cortex (of the orbitofrontal cortex) (also receives input from sensory systems)
patients with ventromedial prefrontal cortex damage
- retained normal intelligence, however
- difficulties planning workday and future
- difficulties choosing friends, partners, and activities
- actions often lead to losses of diverse order: losses in financial status, social standing, family and friends
- choices are no longer advantageous and are remarkably different from he kinds of choices they were known to make in the pre-morbid period
- show a compromised ability to express emotion and to experience feelings in appropriate situations
- show abnormalities in emotion and feelings, along with severe impairments in judgment and decision-making in real-life
deprived of emotional/somatic signal, patients with ventromedial prefrontal cortex damage rely on a reasoned cost-benefit analysis of numerous and often conflicting options, which:
1) degrade the speed of deliberation
2) degrade the adequacy of the choice
Iowa Gambling Task (IGT)
- measures decision-making deficits
- determines if a subject can make a good decision
- used to detect poor judgment and failure to learn from repeated mistakes
- measured emotions as well
behavioral deficit in decision-making is linked to a…
deficit in the ability to generate somatic/emotional signals associated with prior experiences with reward and punishment
ventromedial prefrontal cortex lesions
interfere with the generation of an emotional response from the recall and imagery of an emotional event (secondary induction)
- good memory for the facts of an event, but no emotion expressed with that memory
clinical features and causes of orbitofrontal/ventromedial prefrontal cortex and medial temporal lobe
acute or chronic neurologic disease:
- hemorrhagic leukoencephalitis, herpes simplex encephalitis, and traumatic necrosis of the medial portion of the orbitofrontal/ventromedial prefrontal cortex and medial temporal lobe can precipitate violent rages
- slow growing tumor of the anteromedial portion of the temporal lobe also precipitates fits and rage
children also display these tantrums:
- amygdala develops early but prefrontal cortex later (25 years); children may express “temper tantrums” from early life to get what they want
acquired sociopathy
the personality and decision-making disturbances in patients with orbitofrontal/ventromedial prefrontal cortex (VMPC) damage resemble many of the core features of sociopathy (psychopathy), including: shallow affect, irresponsibility, vocational instability, lack of realistic long-term goals, lack of empathy, poor behavioral control
majority of VMPC patients are not exactly like true psychopaths
- usually begins in adulthood (when the lesion occurs), so not developmental
- generally do not cause physical harm to others
similarities between VPMC patients and sociopathic behavior may include
- general dysregulation of affect
- diminished autonomic responsiveness
- decision-making deficits
core identifying features of acquired sociopathy
- general dampening of emotional experience (impoverished emotional experience, low emotional expressiveness and apathy, inappropriate affect)
- poorly modulated emotional reactions (poor frustration tolerance, irritability, lability)
- disturbances in decision-making, especially in the social real (indecisiveness, poor judgment, inflexibility, social inappropriateness, insensitivity, lack of empathy)
- disturbances in goal-directed behavior (problems in planning, initiation, and persistence, and behavioral rigidity)
- marked lack of insight into these acquired changes
neuropsychological tests used to evaluate visuospatial abilities
- dot counting
- position discrimination, number location
- spatial working memory
optic ataxia
misreaching to peripheral visual targets
- can point at self, therefore not cerebellum
constructional apraxia
difficulty in perceiving spatial relationships
- tested by asking patient to copy a figure or asking patient to copy a block model
hemineglect syndrome
- seen most often with infarcts or other acute lesions of the right parietal or right frontal lobes
- patients often exhibit profound neglect for the contralateral half of the external world, as well as for the contralateral half of their own bodies
- despite their profound deficits, these patients are often unaware that anything is wrong and they sometimes even fail to recognize the left sides of their bodies belong to them
acute hemispatial neglect
- eyes, head, and body turned to right
- failure to orient to left sided stimuli
- failure to search left hemispace
- anosognosia: denial of illness
- aprosodic: flat affect, impaired emotional perception
- motor impersistence: can’t stay on task
anosognosia
denial of illness
aprosodic
flat affect, impaired emotional perception
motor impersistence
can’t stay on task
testing for hemineglect on patient examination
- history: clues to hemineglect include a history of the patient bumping into objects on one side, ignoring food on one side of the plate, or being unaware of deficits
- observation: of the patient’s behavior, movements, and grooming
four main types of testing:
- sensory neglect
- motor-intentional neglect
- combined
- conceptual neglect
testing for sensory neglect - hemineglect
- hemineglect can be present in just one or in more than one sensory modallity
- tactile, visual, or auditory extinction on double simultaneous stimulation
1) establish normal primary sensation by testing each side alone
2) unilateral and bilateral presentations of stimuli should be randomly intermixed and the patient asked to report whether the stimulus was on the right, left, or both sides (eyes should be closed for tactile and auditory testing)
testing for motor-intentional neglect - hemineglect
- should be observed for akinesia or decreased spontaneous movements of unilateral limbs or trunk, or decreases eye movements towards the neglected side
- marked ipsilateral gaze preference (toward the lesion)
- may exhibit motor impersistence, especially of the contralateral limbs
- may have apparently decreased motor power on the neglected side, yet normal power may be demonstrated with increased effort, increased motivation, and active redirection of the patient’s attention to the neglected side
- can demonstrate motor extinction with the patient’s eyes closed by randomly intermixing commands to raise the right arm, left arm, or both
- allokinesia: patient inappropriately moves the normal limb when asked to move the neglected limb
allokinesia
patient inappropriately moves the normal limb when asked to move the neglected limb
combined testing for sensory and motor neglect - hemineglect
- combine sensory and motor modalities
- tactile response test: patients instructed to raise whichever limb is touched, obviating the need for them to attend to and interpret the commands “right,” “left,” or “both”
- pen-and-paper tests
tools used to assess Unilateral Spatial Neglect (USN)
cancellation tests:
- Bells Test
- Albert’s Test
- Line Bisection Test
copying and drawing tests:
- Figure Copying
- Clock Drawing
- reading a newspaper or magazine
- writing
line cancellation test
patient instructed to cross out every line they see by making a cross line right in the middle of each line they
- normal individuals cross every line
- patients with hemineglect often cross the lines seen only on the right side
letter cancellation test
similar to line cancellation test, but patients instructed to find a specific letter
- patients with hemineglect tend to only find that letter on the right side
conceptual neglect
- anosognosia: lack of awareness of the illness
- can be seen in hemineglect as well as Wernicke’s aphasia, frontal lobe disorders, amnesia with confabulation such as Wernicke-Korsakoff syndrome, cortical blindness
- anosodiaphoria: aware that they have severe deficits yet show no emotional concern or distress about it
- hemi-asomatognosia: patient’s deny that the left half of their body belongs to them; a patient may become distressed because “someone left an arm in my bed”
neuroanatomy of neglect
- right sided lesions more common
- 90% of cases due to right temporal-parietal damage
- distributed attention network: temporal-parietal cortex, frontal eye field (FEF)
- thalamus, basal ganglia, thalamus, cingulate, and insula
- most common cause: right middle cerebral artery infarct
neglect theory
hemispheric asymmetry for attention, supported by a larger right frontal lobe in humans
- deficit in the internal representation of space
asymmetric attention control
- when right hemisphere is lesions, you get left neglect since the left hemisphere cannot allocate attention to the left hemispace
- when left hemisphere is lesioned, no or minimal neglect since the right hemisphere can allocate attention to both hemispaces
chronic neglect syndrome
- there is often substantial recovery over the first few weeks to months of hemineglect syndrome
- but the patient is left with parietal lobe deficits and extinction, the failure to perceive two stimuli when simultaneously presented
- extinction can be seen in all modalities, typically visual > somatic > auditory
acalculia
- acquired neurological deficit while dyscalculia is a developmental problem
- patients have difficulty performing simple mathematical tasks, such as adding, subtracting, multiplying and stating which of two numbers is larger
- associated with lesions of the parietal lobe (especially the angular gyrus) and the frontal lobe and can be an early sign of dementia
Gerstmann’s Syndrome
- lesion in the angular gyrus of the interior parietal lobe, usually on the left hemisphere
- cannot read (alexia) due to loss of written comprehension
- cannot write (agraphia)
- inability to do simple arithmetic (acalculia)
- finger agnosia: the inability to distinguish one’s own fingers
- right-to-left confusion
lesions to the angular gyrus tend to lead to…
greater impairments in memorized mathematical facts, such as multiplication tables, with relatively unimpaired subtraction abilities
lesions to the intra-parietal sulcus tend to…
have greater deficits in subtraction, with preserved multiplication abilities
Capgras syndrome
- right hemisphere lesion
- patients insist that their friends or family members have all been replaced by identical-looking imposters
Fregoli syndrome
- right hemisphere lesion
- patients believe that different people are actually the same person in disguise
Reduplicative paramnesia
- right hemisphere lesion
- patients believe that a person, place, or object exists as two identical copies
sensory disturbances due to lesions in the parietal lobe
- lesions posterior to the post-central gyrus (primary sensory cortex) may yield some initial sensory disturbance
- no persistent sensory loss at all; to have this, damage must include the primary sensory cortex
tactile disturbances due to lesions in the parietal lobe
- parietal damage outside the primary sensory cortex
- can lead to astereognosis, ahylognosia, or agraphestisia
astereognosis
inability to judge the form of an object by touch
ahylognosia
impaired discrimination of quality of object such as weight, texture, density
agraphestisia
inability to tell a letter traced on the skin of a patient
visuospatial agnosia
disorders in the judgment of the location or orientation of stimuli both with respect to each other and to the person
- disorders in the “where” pathway
- could result from damage in either hemisphere, with the impairment showing in the contralateral visual field
impairments of memory for location
a specific impairment in the memory of the location of a given stimulus
- seems to occur with either left or right parietal lesions
topographical disorientation and loss of topographical memory
inability to recall the spatial arrangement of rooms within the patient’s house or the furniture within a room
- can occur with either left or right parietal lesions, but more common with right lesions
route finding difficulties
patient may be given verbal directions on how to get somewhere but would get lost and not be able to find the route when doing it
- topographical amnesia
Bálint’s syndrome
- patient cannot judge where things are; feel unsafe to cross roads
- look straight ahead but unaware of objects on either side (bilateral inattention)
- could only report one object at a time (simultagnosia)
- misreached to visual objects (optic ataxia)
- post-mortem: large bilateral strokes involving parietal lobes
bilateral inattention
look straight ahead but unaware of objects on either side
simultagnosia
could only report one object at a time
optic ataxia
misreached to visual objects
