Theory.2Fsource C1 and P1 (neuroscience)

1 theory/source

1.1 p1 reflects cost of attention
1.2 vs. late selection attention models
1.3 c1 , striate cortex
1.4 extrastriate cortex

theory/source
p1 reflects cost of attention

luck et al. (1994) proposed p1 effect reflection of cost of attention. has been shown previously, whenever participant paying attention particular area , target stimulus presented outside wherever participant attending, there decrement in p1 amplitude (e.g. mangun & hillyard, 1991;van voorhis , hillyard, 1977). luck et al. claim decrement cost of attending someplace , being incorrect. decrement or suppression of p1 represents cost of having stop attending 1 area , shift attention place target stimulus located. compared component called n1. n1 shows increment in amplitude when participant attending area , stimulus shown in area. luck et al. (1994) call benefit of attention.

early vs. late selection attention models

one of critical debates c1 , p1 have helped contribute of versus late selection models. selection models such broadbent s filter theory (1958) claim attention filter out unattended information while in middle of processing information. late selection models claim information processed later stage , attention serves choose between processed information. attentional effects on p1 (e.g. van voorhis , hillyard, 1977) show attention can affect visual processing 65ms stimuli appearing in unattended regions of space, having lower p1 amplitude. however, lack of modulation of c1 component due attention or lack thereof (e.g. di russo et al., 2003) shows not information being filtered out immediately. instead, aspects of visual processing (as reflected in c1) seem unfold in manner unaffected allocation of attention on space.

c1 , striate cortex

when first discovered jeffreys , axford (1972), suggested source of c1 component somewhere in v1 (or striate cortex or brodmann s area 17) polarity reversals , reversals side side mirrored retinotopic map of v1. more specifically, suggested c1 generated in brodmann s area 17 or v1. in years findings of studies helped support hypothesis (mangun et al., 1993; parker, salzen, & lishman, 1982). conversely, others found c1 might located in areas such brodmann s area 18 (lesevre, 1982) or brodmann s area 19 (maier, dagnelie, spekrijse, & van dijk, 1987).

however more recent evidence using source localization techniques such brain electrical source analysis (besa) in conjunction fmri points c1 being generated in primary visual cortex of brodmann s area 17. clark, fan, , hillyard (1995) example, using paradigm whereby circular checkerboards presented in different visual fields, localized c1 striate cortex using 2-dipole besa approach. di russo, martinez, , hillyard (2003) used sinusoidally modulated black , white checkerboard circles in 4 different hemifields (upper-right, upper-left, lower-right, , lower-left) @ location of c1. found using besa method, using 7 pairs of dipoles, c1 originated in striate cortex. besa results matched concurrent fmri results same participants.

the extrastriate cortex

the source of p1 component, opposed c1 component, not entirely known. work mangun et al. (1993) presenting bars in different sections of visual field, of presented in attended parts of visual field , not, points neurological source of p1 somewhere on ventrolateral prestriate cortex or brodmann s area 18. make judgment, used both current source density maps , structural mri of participants localize source of p1. other papers using combination of fmri , besa dipole modeling have pointed p1 coming ventrolateral prestriate cortex ( di russo et al., 2003; martinez et al., 1999).

further evidence p1 located along ventral pathway comes studies using both erps , positron emission tomography. these studies have shown p1 associated activation in dorsal occipital areas (woldorff et al., 1998) , posterior fusiform gyrus (mangun, hopfinger, kussmaul, fletcher, , heinze, 1997).