Chapter 7 part 2 Flashcards

1
Q

prefrontal cortex

A
  • areas of the frontal lobe located anterior the motor functional areas (i.e., 4, 6, and 8)
  • outputs to SMA and PMC
  • active when planning behaviors
  • active when new motor skills are being acquired
  • includes areas that mediate higher mental functions
  • language areas located here: Broca’s area (areas 44 and 45)
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2
Q

major divisions of the prefrontal cortex

A

dorsolateral prefrontal cortex (DLPFC), ventrolateral prefrontal cortex (VLPFC), anterior prefrontal cortex (APFC) (frontal pole), medial prefrontal cortex (MPFC) (ventromedial prefrontal cortex)

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3
Q

medial prefrontal cortex (MPFC) or ventromedial prefrontal cortex

A
  • important in decision-making
  • houses orbitofrontal cortex
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4
Q

lesions on lateral side of prefrontal cortex leads to…

A
  • varying degrees of working memory deficits (verbal or non-verbal)
  • executive function deficits: poor inhibitory control, poor reasoning and problem solving; poor planning
  • varying degrees of transcortical motor aphasia: similar to Broca’s, but different from it in that repetition is intact
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5
Q

other functions in frontal lobes

A

the tongue and taste system; olfactory system

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6
Q

taste pathway

A
  • signal begins when a taste cell responds to a tastant
  • 3 cranial nerves (7, 9, 10) carry signals to medulla via nuclear solitary tract (NST)
  • from NST, some fibers go directly to thalamus and some go to limbic regions (e.g., amygdala)
  • from thalamus signals go to insula and gustatory areas, which are also in frontal lobes
  • from there, neurons reach also the orbitofrontal cortex
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7
Q

orbitofrontal cortex

A

thought to be involved in processing the reward value of food and the resulting motivation to eat food

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8
Q

five basic tastes

A

salt, sour, bitter, sweet, and umami

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9
Q

olfactory system

A
  • transduction from odor to neural signal begins when the odorant attaches to a receptor in the olfactory epithelium
  • signal is transmitted to olfactory bulb through tiny olfactory nerves that pass through holes of a bone (cribiform plate)
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10
Q

olfactory bulb relays signals to…

A
  • primary olfactory cortex –> detect a change in external odor
  • orbitofrontal cortex (secondary olfactory cortex) –> identifying smell
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11
Q

key functions in occipital lobe

A

primary visual cortex; “what” and “where” pathways

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12
Q

primary visual cortex

A
  • area 17
  • primary recognition of visual stimuli
  • surrounding it in the occipital lobe is the association visual cortex
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13
Q

optic chiasm

A
  • 50% cross: those from medial half of retina
  • 50% do not cross: those from lateral half of retina
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14
Q

optic pathway

A

optic nerve –> optic chiasm –> optic tract –> synapse at lateral geniculate nucleus –> courses as optic radiations –> primary visual cortex

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15
Q

somatotopy of occipital lobe

A
  • incoming fibers from lower retina stay inferior; form Meyer’s loop and travel in temporal lobe
  • incoming fibers from upper retina stay superior; travel in parietal lobe
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16
Q

low retina

A

superior visual field

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17
Q

upper retina

A

inferior visual field

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18
Q

lesions in lower part of visual system (Meyer’s loop, temporal lobe white matter)

A

lead to upper visual field defects

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19
Q

lesions in the upper part of visual system (parietal lobe white matter)

A

lead to lower visual field defects

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20
Q

occipital lobe divided into…

A
  • inferior visual field on top
  • superior visual field on bottom
    (divided by calcarine sulcus)
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21
Q

primary visual cortex lesions

A
  • lesion in upper calcarine = lower field defect
  • lesion in lower calcarine = upper field defect
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22
Q

testing visual fields

A
  • perimetry: done with a computer; more precise, takes more time, more cost; looks for defects and charts their locations by having the patient stare at a light while other lights are flashed in the periphery
  • confrontation method: done with fingers; less precise, quick and cheap
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23
Q

clinical signs of visual defects due to prechiasmal lesions

A
  • if lesion is in retina –> visual field defects are usually: horizontal (left or right half of visual field), apex pints toward blind spot
  • if lesion is in optic disc –> defecs are usually: vertical (superior or inferior half of visual field), constriction of visual field, enlarged blind spot
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24
Q

macular (central) vision sparing

A
  • colateral from other arteries like middle cerebral artery
  • spares the center of vision so that it is kept intact in both eyes
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25
Q

lesions in lateral side of occipital lobe beyond primary visual disturbances that are not associated with blindness

A

deficits in two streams of information: “what” and “where” pathways

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26
Q

areas of parietal lobe

A

primary sensory cortex and lateral left parietal lobe

27
Q

Wilder Penfield

A

stimulated the sensory cortex in awake epilepsy patients and had report the sensations they felt:
- created a topographical map that represented the body surface on the primary sensory cortex (the homunculus)
- discovered that different body parts had disproportionate cortical representation (e.g., hands are very large)
- Penfield discovered 1 humonculus, but subsequent electrophysiological research revealed that there could be as many as 4 humonculi lined up next to each other representing sensations from muscle movement, pain and temperature receptors, discriminative touch, and proprioception

28
Q

primary sensory cortex (S1)

A
  • areas 3, 1, and 2
  • somatotopic maps of contralateral body sensations
  • receive projections from contralateral half of body
  • proprioceptive information from muscles and joints arrive here, relaying info about the position of body parts in relation to one another
  • links to motor regions in frontal lobes
29
Q

lesions of primary sensory cortex (S1)

A
  • varied degrees of focal impairment in sensation on the contralateral side of the body
  • acute (immediate) stage
  • chronic (later) stage
30
Q

why do sensory modalities recove in the chronic (later) stage of lesions of primary sensory cortex (S1)

A
  • secondary sensory cortex compensates
  • thalamus compensates for sensation of pain and temperature
  • all sensory cortices like vision and audition compensate for quality and intensity of pain
  • insula and secondary somatosensory cortex allow for asymbolia for pain (sensation of pain without unpleasantness)
31
Q

acute (immediate) stage of lesions of primary sensory cortex (S1)

A

loss of all sensory modalities on the contralateral side of body and/or face

32
Q

chronic (later) stage of lesions of primary sensory cortex (S1)

A
  • recovery of sensation of pain and temperature and crude touch sensation
  • continued loss of fine aspects of tactile information on contralateral body (arm and face): loss of two-point discrimination, agraphesthesia (inability to recognize a letter outlined on the skin), astereognosis (inability to recognize form), loss of vibration and light touch
  • continued loss of proprioception in contralateral body (arm and face); if leg is involved, see positive Romberg sign (ataxia when eyes are closed)
33
Q

agraphesthesia

A

inability to recognize a letter outlined on the skin

34
Q

astereognosis

A

inability to recognize form

35
Q

lateral left parietal lobe (rostral inferior parietal lobule)

A
  • involved in complex gesture and action responsibilities
  • “mirror neurons”: imitation as a form of learning; emergence of spoken language from hand gestures
36
Q

lesions of lateral left parietal lobe

A

apraxia –> patient loses the sense of what a particular movement is for (cannot recognize a gesture made by others or implement a movement when ordered)

37
Q

Wernicke’s area

A
  • mainly in temporal lobe
  • surrounding sensory language areas (angular gyrus and supramarginal gyrus) in parietal lobe
  • mostly in the left hemisphere because language is mostly lateralized to the left hemisphere
  • connected to Broca’s area through the arcuate fasciculus (mostly in parietal lobe)
38
Q

areas of parietal lobe

A

Wernicke’s area and association sensory cortex

39
Q

association sensory cortex

A

superior and inferior parietal lobules

40
Q

lesion in inferior parietal lobe

A
  • at the angular gyrus: alexia (inability to read written language)
  • at the supramarginal gyrus: conduction aphasia (understand what is said, but unable to repeat it)
41
Q

alexia or dyslexia

A

inability to read written language
- alexia: acquired (e.g., stroke)
- dyslexia: developmental

42
Q

conduction aphasia

A

understand what is said, but unable to repeat it
- damage to inferior parietal lobe at supramarginal gyrus

43
Q

optic ataxia

A

inability to accurately point to or reach for objects under visual guidance in contralateral hand
- damage to superior parietal lobe; can occur in either hemisphere and affects contralateral side

44
Q

alexia

A

damage to inferior parietal lobule at the angular gyrus

45
Q

anosagnosia

A
  • left visual field neglect
  • a lack of awareness or denial of one’s own neurological deficit; in this case, the person might not realize they have a problem with their vision
  • damage to areas involving the inferior parietal lobe
46
Q

left visual field neglect

A

the person has difficulty paying attention to or processing information in the left side of their visual field
- often due to damage in the right hemisphere in the inferior parietal lobule

47
Q

key functions of temporal lobe

A
  • olfaction
  • audition
  • memory: medial temporal lobe
  • areas overlapping with inferior occipital cortex: visual perception (“what” pathway)
48
Q

olfaction

A
  • olfactory nerve consists of multiple tiny nerve cells with axons that terminate in the olfactory bulb, which belongs to the central nervous system
  • complex set of olfactory receptors on different olfactory neurons can distinguish a new odor from background environmental odors and determine the concentration of that odor
  • axons from the olfactory sensory neurons converge in the olfactory bulb to form clusters called glomeruli
  • inside each glomerulus, the axons contact the dendrites of mitral cells and several other types of cells
49
Q

brain areas that mitral cells send signals to

A
  • anterior olfactory nucleus
  • piriform cortex
  • medial amygdala
  • entorhinal cortex
  • olfactory tubercle
50
Q

piriform cortex

A

area most closely associated with identifying the odor

51
Q

medial amygdala

A

involved in social functions and associating an odor with an emotional reaction

52
Q

entorhinal cortex

A

associated with memory

53
Q

anosmia

A

loss of smell
- can be indicative of a serious neuropsychological problem (indicates there is a problem with one of the brain areas that the mitral cells signal to)

54
Q

audition in the temporal lobe

A

primary auditory cortex; auditory association cortex

55
Q

primary auditory cortex

A
  • represent the acoustic frequencies and intensities of a large range of pitched and unpitched sounds (speech, music, environmental noises) so as to permit their recognition and spatial localization
  • receives information from both ears (therefore, unilateral damage does not cause deafness)
56
Q

auditory association cortex

A
  • surrounding the primary auditory cortex in the posterior and superior parts of the temporal cortex
  • concerned with the memory and classification of sounds (language comprehension)
57
Q

auditory agnosia

A

pure word deafness (verbal auditory agnosia)
- cannot recognize speech sounds, but can recognize non-speech sounds and can produce normal speech
- unilateral lesions in dominant hemisphere

58
Q

Wernicke’s aphasia

A

inability to comprehend language
- lesion in auditory association cortex, only in left hemisphere

59
Q

non-verbal auditory agnosia-amusia

A

inability to recognize non-verbal sounds, including music and tone
- unilateral lesion in non-dominant hemisphere

60
Q

amygdala

A

attaching emotional significance to events
- when damaged, there is a marked decrease in the ability to express emotions

61
Q

memory in temporal lobe

A

cortical and subcortical structures of the limbic system
- entorhinal cortex
- hippocampal formation
- lesions: anterograde memory impairment (cannot form new memories)

62
Q

commissurotomy

A

when hemispheres cannot communicate with each other
- cortical connections between homotopic points of the two hemispheres are severed
- each hemisphere therefore functions independently of the other and without access to the other’s sensations, thoughts, or actions
- put object in left hand (sensory information gets to right hemisphere); cannot name the object
- put the same object in the right hand, the patient can name it

63
Q

Wada test

A

to see on which side is language before surgery
- inject sodium amobarbital into the carotid artery
- the sodium amobarbital anesthetizes the hemisphere on the side where it is injected, allowing the surgeon to determine whether that hemisphere is dominant for speech