Disorders of Attention Flashcards
lesions in the ‘where’ stream lead to…
deficits in spatial attention
patient RM had…
two strokes which damaged large areas of bilateral-occipito cortex
primary impairment of balint’s syndrome
simultanagnosia- inability to focus attention on multiple objects
what does simultanagnosia lead to?
considerable conjunction errors when seeing objects for over 10 seconds
what is the parietal lobe important for?
feature binding and visual attention
evidence of parietal lobe activity
- greater activity during conjunction search
- conjunction search disrupted by TMS
hemispatial neglect
lack of awareness of stimuli presented to the side of space on the opposite side to the brain damage (contralesional side)
symptoms of hemispatial neglect
- deficit to attend to information in contralesional space (sensory, representational, and bodily)
- unilateral neglect is object based rather than space based (left-hand side of all objects)
what do hemispatial neglect patients also experience?
extinction deficits, suggesting different perceptual representations can locally compete for attention
what is neglect an impairment of?
the bottom-up stimulus driven system
what are neglect and extinction deficits of?
attention
what are ERPs used to observe?
when neglect occurs in the visual stream
what do ERPs observe in neglect patients?
early processing in neglect patients is similar to controls, but after 150ms there is a large difference
what does experimental psychology show about neglect patients?
they fail to accurately identify objects presented to the neglected field- there is no conscious access
priming effect in neglect patients
patients can be faster to respond to a semantically related word despite neglecting stimuli, suggesting meaning must be partially processed
where is neglect seen?
in damage to right, inferior parietal lobe
what does TMS produce?
extinction symptoms
what do neglect patients benefit from?
endogenous cues in both visual fields, as top-down processing is needed to consciously pay attention to the neglected side of space
when are neglect patients most impaired?
when trying to disengage attention from intact side (struggle with invalid targets failing to activate the exogenous system)
attention in neglect patients
related to disengaging endogenous attention of attentional spotlight from the ipsilesional side of space, to something happening in the contralesional space
most common neurodevelopmental disorder in children
ADHD, around 5%
three subtypes of ADHD
- predominantly inattentive
- predominantly hyperactive/impulsive
- combined inattentive and hyperactive/impulsive
predominantly inattentive
difficulty in finishing tasks, following instructions, and becoming easily distracted
predominantly hyperactive/impulsive
difficulty sitting still for long periods, fidgeting, and speaking at inappropriate times
combined inattentive and hyperactive/impulsive
most common subtype
what does the DSMV require for a clinical diagnosis?
at least 6 inattention symptoms and 6 hyperactivity/impulsivity symptoms
when must symptoms be present?
before age of 12 and cause significant impairments in social and academic functioning for a clinical diagnosis
structural impairments of ADHD
- 3-4% reduces cortical volume, particularly prefrontal
- reduced grey matter and cortical connectivity in fronto-parietal attention network
- reduced cortical connectivity between hemispheres
functional impairments of ADHD
hypoactivity in prefrontal cortex and endogenous attention network
molecular impairments of ADHD
imbalance in dopamine and noradrenaline circuits
ADHD treatments
methylphenidate and dextroamphetamine
how do ADHD treatments work?
facilitate release of noradrenaline and dopamine to enhance prefrontal cortex and basal ganglia availability
