disorders of attention (week 5) Flashcards
what is hemispatial neglect?
a lack of awareness of stimuli presented to the opposite side of space to where their brain damage is (contralesional)
what are the symptoms of hemispatial neglect?
- deficit to attend to information in contralesional space - for external sensory information, for information in the “mind’s eye” and for bodily space
- representational neglect
- unilateral neglect is often object-based irrespective of the object’s position in space
what happened to patient RM (Treisman, 1999)?
- patient RM had two large strokes damaging large areas of the bilateral occipito-parietal cortex
- had particular problems combining features of a stimulus - the parietal lobe (‘where’ pathway) is important for feature binding
what is visual extinction?
the phenomenon of visual extinction suggests different perceptual representations are competing for attention and visual awareness
how much is neglected for patients with hemispatial neglect?
DI Russo et al., 2008 - ERPs elicited by visual stimuli in the left visual field (neglected side) - early processing relatively preserved - so, a lot of basic perceptual processing happens to things in the neglected field
how much is processed for patients with neglect?
- McGlinchey-Berroth et al., 1993 - patients with neglect cannot accurately identify objects presented to the neglected field, therefore no conscious access of what they have seen
- using priming stimuli: an object presented to the neglected field can change the patient’s behaviour, baseball bat shown in the neglected field isn’t consciously experienced but makes response to semantically related word faster - the meaning of the neglected object must have been processed
what are the regions underlying neglect?
the right inferior parietal lobe
how can we explain neglect/extinction?
both are deficits of attention and not perception
what exactly is impaired in neglect?
- studies by Smania et al (1998) and Bartolomeo et al (2001) suggest that the endogenous orienting system is relatively intact in neglect patients
- disengagement of attention - neglect patients most impaired when trying to disengage attention from the intact side - exogenous system is impaired
what are the subtypes of ADHD (attention deficit hyperactivity disorder)?
- predominantly inattentive - difficulty in finishing tasks, following instructions, and easily distracted
- predominantly hyperactive/impulsive - difficulty in sitting for long periods, fidgeting, speaks or acts at inappropriate times
- combined inattentive and hyperactive/impulsive - the most common subtype
what are some of the symptoms of inattention (DSM-V diagnostic criteria)?
- difficulty sustaining attraction
- easily distracted
- doesn’t appear to listen when spoken to directly
- poor attention to details
- forgetful in daily activities
- loses things necessary for tasks
(at least 6 required)
what are some of the symptoms of hyperactivity and impulsivity (DSM-V diagnostic criteria)?
- has difficulty in playing quietly
- is always ‘on the go’
- talks excessively
- blurts out answers before the question is complete
- cannot wait for their turn
- interrupts or intrudes on others
(at least six required)
what are the requirements for an ADHD diagnosis?
- symptoms must be present before the age of 12
- clinically significant impairment in social or academic functioning
- some symptoms that cause impairment are present in 2 or more settings
- not due to another disorder e.g., autism
what are some of the causes of ADHD?
- heritability - parents/siblings of a child with ADHD are 4-5 times more likely to have a diagnosis
- prenatal exposure to alcohol and nicotine
- premature and low birth weight, and prenatal brain injury
- environmental toxins e.g., lead, pesticides
what are the structural features of ADHD?
- 3-4% reduced overall cortical and especially prefrontal volume
- reduced grey matter specifically in frontoparietal attention network
- reduced cortical connectivity (white matter tracts) between hemispheres and within frontoparietal attention networks
