Attention neuronal

• Individual neurons in monkey temporal cortex


  • Show 'preferences' for particular stimuli
  • Chelazzi (1993)
• Attentional competition- Chelazzi et al (1993) 


  • Occurs at the level of individual neurons
  • Involves both excitation (increased firing rate of neurons to stimulus) and inhibition (suppression of firing rate of neurons)
  • Modulation of neuronal responses by attention occurs before response
  • Competition occurs in brain regions that process the visual features of objects
  • The same neurons that process the visual features of an object resolve the competition for selection
• Attentional modulation effects occur early in the processing stream
• Retinotopic mapping


  Used to examine which areas of visual cortex were sensitive to visual stimulation in different regions of space
• Brefczynski and DeYoe (1999)

  • Activation in V1 during attentional cueing
  • Effects occurred in V1 - shows attention enhances processing in the earliest stages of visual processing
• ERP and fMRI studies converge to show attentional modulation of cortical signals in primary visual cortex (V1)
• Kastner et al (1998) findings:

  • Activation in V4 = lower when items presented simultaneously than sequentially (due to attentional competition)
• O'craven et al (1999) findings

  • Activation in FFA and PPA depended on which stimulus was being attended to
• Attention is flexible with the level of filtering depending on perceptual load
• Schwartz et al (2005)

  • Perceptual load affects visual cortex activation
• Competitive effects of attention can be observed throughout brain regions in the ventral visual pathway
• Selective attention = gateway into consciousness

  • Filters sensory infoby enhancing baseline neuronal firing in task-relevant areas of visual cortex and suppressing neuronal firing in task-irrelevant brain regions
• Attentional signals may originate in frontoparietal cortex
• fMRI provides correlation data, and we can't infer causation
• TMS over Frontal Eye Fields


  Effects on activation in visual cortex - Taylor et al (2006)
• Taylor et al 2006 findings:

  • Attentional selection may involve long-distance interactions between prefrontal cortex and visual cortex
  • Faster to respond to validly cued targets than invalidly cued targets
  • Responses = slower during TMS of the frontal eye fields
• Neuronal frequency synchronisation


  Rhythmic or repetitive patterns of neuronal activity
• Different EEG frequency bands might correspond to different functions
• Buschman & Miller (2007)

  • Frequency synchronisation between brain regions might support selective attention
• Synchronisation between parietal and prefrontal regions


  • Higher in middle frequency (beta band) during conjunction search
  • Higher in upper frequency (gamma band) during pop-out
• Gonzalez et al (1994) ERPs findings:

  • If a cue was previously presented pointing to location - brain activation in early visual cortical areas = higher than when cue pointed to the other location