W4 Flashcards
Legions in what stream causes what?
Specific impairments in object recognition
Legions in where stream causes what?
Deficits in spatial attention
What is Balint’s Syndrome?
Balint’s Syndrome is characterized by damage to large areas of bilateral occipito-parietal cortex. Among other impairments, individuals with Balint’s Syndrome are unable to focus attention on more than one object at a time (simultanagnosia). They also experience particular difficulties combining features of a stimulus, often making conjunction errors even when presented with objects for extended durations. This syndrome highlights the importance of the parietal lobe (the “where” pathway) in feature binding.
What part of the brain seems to have a role in feature binding/conjunction search?
- During conjunction search, posterior temporal cortex and parietal cortex show increased activation over baseline control conditions
- TMS to parietal lobe disrupts conjunction search but not feature search
- Stimulation of intraparietal sulcus reduces illusory conjunctions
- All this evidence suggests parietal cortex must play a role
What is hemispatial neglect?
Hemispatial neglect involves issues with exogenous attention and manifests as a lack of awareness of stimuli presented to the side of space opposite to the brain damage (contralesional). Individuals with hemispatial neglect often only describe or attend to objects on one side of space, typically the right side.
What is extinction?
Extinction is a phenomenon in which individuals detect a single stimulus presented to one visual field (typically the left), but fail to detect the same stimulus when another stimulus is simultaneously presented to the other visual field. This suggests that different perceptual representations are competing for attention and visual awareness.
What is covert attention?
Covert attention refers to attention that is allocated without explicitly orienting sensory organs in that direction. The Posner Cueing Paradigm is a common experimental method used to study covert attention.
What does the priming effect shown in patients with hemispatial neglect tell us about attention?
In patients with hemispatial neglect, the priming effect occurs when a stimulus is presented in the neglected field, which is not consciously experienced, but it makes them faster to respond to a semantically similar stimulus. This indicates an impairment in attention and conscious accessing rather than a perception impairment. It suggests that all the information was processed visually but couldn’t be accessed due to attentional deficits.
What brain lesions underlie neglect?
Neglect is associated with lesions in the right inferior parietal lobe, including the temporo-parietal junction and angular gyrus. Transcranial magnetic stimulation (TMS) on these regions can induce neglect- and extinction-like symptoms in control participants.
How can neglect and extinction be explained?
Neglect and extinction are deficits of attention rather than perception. Corbetta and Shulman (2002) argue that neglect mainly arises from impairment of the stimulus-driven system, indicating an attentional impairment rather than a stimulus processing deficit. It suggests that lesions in different brain regions associated with various types of attention, particularly the bottom-up exogenous attention system, contribute to neglect.
What is ADHD?
ADHD stands for Attention Deficit Hyperactivity Disorder. It is the most common neurodevelopmental disorder diagnosis in children, characterized by symptoms of hyperactivity, impulsivity, and inattention beginning in childhood. ADHD affects approximately 5% of children and persists into adulthood in about 2.5% of cases.
What are the ADHD Subtypes?
- Predominantly inattentive; Difficulty in finishing a task, following instructions; easily distracted.
- Predominantly hyperactive/impulsive; Difficulty in sitting still for long periods; fidgeting; speaks or acts at inappropriate times.
- Combined inattentive and hyperactive/impulsive; The most common subtype
What are the DSM-V diagnostic criteria for inattentive ADHD?
According to the DSM-V, inattentive ADHD is diagnosed if an individual exhibits at least six of the following symptoms: poor attention to details, difficulty sustaining attention, not listening when spoken to directly, difficulty following instructions or completing tasks, difficulty organizing tasks and activities, avoidance of tasks requiring sustained effort, losing things necessary for tasks, being easily distracted, and forgetfulness in daily activities.
What are the DSM-V diagnostic criteria for hyperactive and impulsive ADHD?
According to the DSM-V, hyperactive and impulsive ADHD is diagnosed if an individual exhibits at least six of the following symptoms: fidgeting with hands or feet, leaving one’s seat when expected to remain, excessive running about or climbing, difficulty playing or engaging in leisure activities quietly, always being “on the go,” excessive talking, blurting out answers before questions are completed, difficulty waiting one’s turn, and interrupting or intruding on others.
ADHD - Aetiology?
Heritability: Parents and siblings of a child with ADHD are 4-5 times more likely to have a diagnosis of ADHD.
Prenatal exposure to alcohol and nicotine.
Premature birth and low birth weight.
Perinatal brain injury.
Exposure to environmental toxins such as lead and pesticides.
