Alertness, attention, awareness
According to Posner's model, ADHD is associated with deficits in which attentional network?
Alerting - difficulty in obtaining the effect of the warning signal, in maintaining the alert state where no warning or of focusing the warning signal to improve orienting
4 aspects of attention according to Cohen, Malloy, & Jenkins
Sensory selective attention - process by which sensory input is chosen for additional processing & focus Attentional capacity & focus Sustained attention Response selection & control (strongly associated with exec fx)
Condition involving alterations in level of arousal/consciousness, difficulty staying alert, disturbance of attention, & impairment in logical stream of thought
According to Posner's model, autism is associated with deficits in which attentional network?
Orienting - clear deficit in ability to shift covertly to a target, whether or not it is toward social events
Erroneously report location of stimulus given to the right side of the body as being on the left
State of being awake but drowsy, inactive, & indifferent to external stimuli
Barkley's definition of ADHD
D/o of sustained attention, behavioral inhibition, & exec fx
Environmental factors associated with attentional deficits
Poverty assoc. malnutrition & infection, maternal ETOH use & FAS, pregnancy & birth complications, lead exposure, lack of intellectual stimulation
Diagnostic considerations for altered arousal
Primary intracranial disease (affects the RAS by compression on brainstem) Systemic disease affecting the CNS Toxins/metabolic conditions Drug withdrawal
Engaging with stimuli involves what part of the thalamus?
Thalamic lesions may produce what type of attentional impairments?
Info gating & selection difficulties
Bottom-up modulation (Mesulam)
Influence of the ascending reticular activation system; global influence on attention without selectivity for sensory modality or cognitive domain
What is the prefrontal cortex's role in attention?
Response selection, sustained attention, control, switching & searching
Orientation is a reliable integration of
Attention, perception, & memory
What is the limbic system's role in attention?
Establishes salience, whereby determining priority of incoming stimuli; limits of attention (hippocampus - memory encoding & retrieval constrain attention)
Describe Posner's orienting network
Ability to select specific info from among multiple sensory stimuli Involves pulvinar, superior colliculus, superior parietal lobe, temporoparietal junction, superior temporal lobe, frontal eye fields, splenium of CC
Individual factors that may influence attention assessment
Energy, effort, motivation, cognitive ability, mood state
Describe Posner's alerting network
Ability to increase & maintain response readiness in preparation for an impending stimulus; activity in frontal & parietal regions, particularly of RH, & posterior limb of IC
Failure to respond to stimuli on the CL side of space in absence of obvious weakness; cannot be attributed to sensory deficit or inattention; marked ipsilateral gaze preference common
What are the 3 attention networks according to Posner?
Alerting Orienting Executive
What are mental activity variables (Lezak)?
Efficiency of mental processes involved in cognitive functions, but do not have unique behavioral end products (i.e., attention, activity rate, consciousness)
Most common sites of damage associated with neglect
Inferior parietal lobe, also sometimes in frontal cortex, cingulate gyrus, BG, thalamus, reticular formation
Minimally conscious/responsive state
Inability to interact consistently with the environment even though some environmental awareness exists (e.g., selective visual tracking, intermittent nonflexive motor activity)
What is the link between arousal & attention (Lezak)?
D/o of arousal always involves d/o of attention; d/o of attention does not always involve d/o of arousal
According to Cohen et al., attentional capacity & focus is influenced by what 2 factors?
Energetic factors (motivation, arousal, effort) Structural factors (memory, processing speed, cognitive ability)
Endo-evoked vs. exo-evoked
In regards to motor extinction, does the patient move the limb on their own (endo) or do they move in response to stimuli (exo)
Intensive care unit (ICU) psychosis
Development of confusion following major surgery, thought to be related to extended periods in sterile hospital room with minimal stimulation, no regular routine, pain, & frequent staff awakenings
Acute confusional state: 6 major groups of causes
1) toxic-metabolic encephalopathy 2) environmental stressors in vulnerable individuals 3) multifocal brain lesions 4) epileptic seizures 5) space-occupying lesions 6) focal brain lesions
What is the ascending reticular activating system's role in attention?
Provides activating stimulation to cortex to initiate & maintain arousal necessary for initial & sustained attention
What are the 3 essential factors of attention, according to Pibram & McGuiness?
Arousal ('primordial attention system') Activation (basal ganglia) Effort
According to Cohen et al., sustained attention is dependent on
Task duration, vigilance requirement, reinforcement & target distractor ratio
Subcortical lesions may produce what type of attentional impairments?
Impairments of arousal, activation, info processing speed
Persistent vegetative state
Condition of profound nonresponsiveness in the wakeful state that is caused by brain damage; absence of discernible adaptive responses to external environment
Failure to detect stimuli presented on side CL to CNS lesion; extinction to double simultaneous stimulation
What other features are associated with delirium?
Disturbance in sleep-wake cycle, disorientation to time & place, rambling or incoherent speech, illusions, visual hallucinations, agitation, change in psychomotor behavior
Describe Mesulam's attentional matrix
Domain-specific attentional processes (attentional processes to certain stimuli) Domain-independent attention processes ('bottom-up' & 'top-down')
Coma can be caused by damage to
B RAS, B diffuse cortex, B lesions of thalamus
Pts deny that the left half of their body belongs to them
Unconscious state from which patient can be partially aroused but can't reach a fully wakeful state of awareness
Pt inappropriately moves the normal limb when asked to move neglected limb
Describe Posner's executive network
Monitoring & resolution of conflict between computations in different neural areas Involves cingulate gyrus, insula, parts of the BG, anterior corona radiata Activated during cognitive conflict tasks (e.g., Stroop), behavioral & emotional control
Top-down modulation (Mesulam)
Parietal, limbic, prefrontal cortex; provides info on context, modulation, significance, & volition
3 primary features of acute confusional state
Disturbance of vigilance, distractibility, impaired working memory Inability to maintain stream of thought Inability to carry out goal-directed movement
What is the dorsolateral frontal cortex's role in attention?
Sequencing, persistence, switching, focus
Focal frontal lesions may produce what type of attention impairments?
Focused attention, response selection & control
According to Hebb, every stimulus has what 2 effects on the brain?
To maintain the alert state (increased activity of NE pathways) To activate sensory pathways
Transient impaired consciousness in which pt may perform certain acts involuntarily without subsequent memory for those acts; may be seen in recovery from general anesthesia
A type of motor neglect; the pt does not demonstrate akinesia when asked to move one limb at a time, but doesn't use affected limb when both are needed
Uremia from end-stage renal kidney failure is associated with
Deficits in sustained attention; EEG pattern similar to absence epilepsy; toxins assoc. w/ kidney failure 'attack' centrecephalic brainstem structures implicated in absence epilepsy
Mirksy's 5 elements of attention
Focus (superior temporal & inferior parietal, CC)/execute (inferior parietal & CC) Sustain (rostral midbrain) Shift (prefrontal, frontal association) Encode (hippocampus, amygdala) Stabilize (midline thalamic & brainstem structures)
What is the orbital frontal cortex's role in attention?
Response initiation, inhibition
According to Posner's model, anxiety disorders are associated with deficits in which attentional network?
Orienting - trouble orienting away from a stimulus with a negative emotional valence
When pts are asked to imagine a scene or part of body, may fail to report portions on side opposite lesion
Deficits in sustained attention are seen among 1st degree relatives of patients with what disorder?
Demographic & medical risk factors for delirium
Age, previous cognitive compromise, chronic medical condition, prolonged hospitalization, sensory deprivation, sleep-wake disturbance, medical procedures with high BP volume loss/exchange, prolonged bypass, occupational exposure to toxins, medications
What is the inferior parietal cortex's role in attention?
Spatial selective attention; hemineglect