Attention

• Hemineglect (hemi-attention)


  A spatial phenomenon where lesion to one part of the brain results in ALL INFORMATION on the opposite side (contralateral) to the lesioned are ignored
• Hemineglect


  • Individual could have intact sensory and motor functioning
  • The neglect of info occurs with reference to spatial frame
  • Often involves damage to the right parietal lobe because the parietal lobe plays in spatial processes
• Posterior parietal cortex (Areas 5/7)


  Involve somatosensory integration and also visual input
• Selective attention


  A category of attention that involves the selection of information essential to a task
• Selective attention


  • Often conceptualized as a filtering process that allows us to hone in on critical information from the vast amount of information available
  • Includes information we are keeping "in mind" or set of possible responses
  • Cognitive mechanism that allows one to select—from all the possibilities present to one--- the task of comprehension as the most salient aspects of processing that must be accomplished at this time
• Divided attention


  Kind of attention that we use when we have to split our attention across tasks. Also known as "multitasking"
• Divided attention


  • The resource, or effort, that is required to process information is central to this concept
  • Multiple-resource theory: suggest that a limited set of distinct resource pools may exist, each of which can be applied only to certain types of processes meaning that the processing capacity of the brain is larger when tasks DRAW FROM DIFFERENT RESOURCE pools than from the same one (e.g. performing an auditory and visual task simultaneously)
• Reticular activating system (RAS)


  The brain system responsible for overall arousal which is the basic level of attention which requires the nervous system to be RECEPTIVE to stimulation
• Reticular activating system (RAS)


  • Also responsible for sleep-wake cycles
  • Also critical for alertness
  • Cells in the ascending RAS connect to the cortex occur via two routes: Dorsal system (travels to the cortex via the thalamus, relies on acetylcholine) and Ventral route (travels to the basal forebrain and subsequently onto the cortex, relies on noradrenergic system and the serotonergic system)
• Early vs. late selection

  Two schools of thoughts developed to answer the question of when selection attentional selection occurs. At which level of processing do we decide to attend to?
• Early selection viewpoint


  • Suggests attentional selection occurs at an early stage of processing before items are identified
• Late-selection viewpoint


  • Argues that selection occurs only later sensory processing is complete and items have been identified and categorized
• Event-related potential (ERP) studies provide information on when processes occur. ERP studies state that attention selection can occur BOTH earlier and later in processing (not an either-or proposition)
• ERP/MEG studies: some relatively automatic filtering of GATING of sensory information occurs very soon after the receipt of a stimulus
• Arousal


  Involves the ability to extract information from environment or to select a particular response among other possible alternatives
• Arousal


  • Alertness and arousal are particularly low when tired or sleepy
  • Extreme cases include comas
• Cocktail party effect


  In a party, you have no problem concentrating on your conversation despite all other conversations and there is little difficulty to switch focus from one conversation to another
• Shadowing


  A different message is played to each ear however there is a particular task where participant overtly repeat the message played in one ear
• Covert vs. overt attention


  • Covert: Paying attention without moving the eyes
  • Overt: Selectively processing one location over others by moving the eyes to point at that location
• Endogenous vs. exogenous attention


  • Endogenous: "top-down" processing – internally generated
  • Exogenous: "down-up" processing – sensory driven
• Dichotic listening task


  A different message is played to each ear. When voices had the same physical properties, participants could not separate the messages using MEANING ONLY
• Attentional effects on ERP, (e.g., P50, N1): Event-related potential (ERP) studies provide information on when processes occur. ERP studies state that attention selection can occur BOTH earlier and later in processing (not an either-or proposition)
• Sensory gating


  First and auditory stimulus is presented followed by the same auditory stimulus 500 ms later. The degree to which the response is diminished on the second presentation as compared to the first is the measure of gating
• Sensory gating


  • Gating is adaptive, meaning the brain has also processed or prioritized that info. and such the second time not much ATTENTION or prioritizing is needed
  • A diminished response to the second stimulus is reflected in an ERP component known as the P50, which occurs 35-85 ms after receipt of auditory information
• Frontal eye fields (FEFs)


  Located at the ventral end of the premotor cortex and above Broca's area. Controls the voluntary execution of eye movements
• Frontal eye fields (FEFs)


  • Voluntary vs. reflexive eye movements: Reflexive are under the control of the superior colliculus
  • Damage here makes it difficult to suppress automatic eye movements that occur when an attention-grabbing stimulus appears in the periphery because the FEF cannot inhibit the response
  • Exhibits activity prior to the onset of the movement, and may code for multiple potential movements
• Default mode network (DMN)


  A network of brain regions that is activated when attention is diverted inward than towards outward stimuli or while the brain is at a resting state, meaning it is not occupied with outside environment
• Default mode network (DMN)


  • Could be divided into three subsystems: Core regions (anterior medial prefrontal cortex, posterior cingulate cortex), Medial temporal (portions of the medial temporal lobe, ventral posterior cingulate cortex, posterior parietal region), Dorsal medial (portions of the superior and inferior frontal cortex, anterior insula, temporoparietal junction, and anterior ventral temporal regions)
  • Activity in the DMN is reciprocal to activity in attentional control structures (Dorsolateral prefrontal cortex, inferior parietal region, SMA), such that when activity in the attentional network increases, activity in the connectivity of the DMN is suppressed