Folie 1

1
The functional meaning of the N1/N200 and P200
component
The traditional view is that the N1 component
reflects primarily attentional processes. More
recent findings, however suggest that at least
at occipitotemporal sites - the N1 reflects the
encoding of specific objects such as words,
faces or flowers. The findings illustrated on
the next pages are taken from Allison, T., Puce,
A. McCarthy, G. (2002). Category-Sensitive
Excitatory and Inhibitory Processes in Human
Extrastriate Cortex. Journal of Neurophysiology,
88, 2864-2868. Background of the
study Single-cell recordings from the temporal
lobe of monkeys viewing complex stimuli show that
cells may be highly selective, responding for
example to complex nonobjects or to objects such
as faces (reviewed by Desimone 1991 Perrett et
al. 1992) and hands. Conversely,
stimulus-selective cells may be inhibited by
nonpreferred stimuli. Part of the specificity of
such cells results from local inhibitory
interactions. In this study, inhibitory
interactions were inferred from event-related
potential (ERP) recordings made directly from the
surface of the fusiform gyrus and adjacent
cortex, regions known from neurophysiological and
neuroimaging studies to be involved in the
perception of faces, objects, and
words. DESIMONE R. Face-selective cells in the
temporal cortex of monkeys. J Cognit Neurosci 3
18, 1991. PERRETT DI, ORAM MW, HARRIES MH,
BEVAN R, HIETANEN JK, BENSON PJ, AND THOMAS S.
Viewer-centred and object-centred coding of heads
in the macaque temporal cortex. Exp Brain Res 86
159173, 1991.
2
Face specific site
Word specific site
Faces Words Flowers
FIG. 1. A at this face-specific N200 site, other
categories of stimuli generated small N200s. B
at this word-specific N200 site, other categories
of stimuli generated no clear event-related
potentials (ERPs) in the latency range of N200.
C example of an N200 evoked by faces and a P200
evoked by words at a face-specific N200 site. D
example of an N200 evoked by words and a P200
evoked by faces at a word-specific N200 site. E
at this face-specific N200 site, words and
flowers evoked P200s. F at this word-specific
N200 site faces, scrambled faces and flowers
evoked P200s.
Sc Faces Sc Words
D Word specific site
C Face specific site
Faces
Words
Faces
Words
E Face specific site
F Word specific site
words flowers
Faces, scrambled faces flowers
From Allison, T., Puce, A. McCarthy, G.
(2002). Category-Sensitive Excitatory and
Inhibitory Processes in Human Extrastriate
Cortex. Journal of Neurophysiology, 88, 2864-2868.
Words
Faces
3
Allison, T., Puce, A. McCarthy, G. (2002).
Category-Sensitive Excitatory and Inhibitory
Processes in Human Extrastriate Cortex. Journal
of Neurophysiology, 88, 2864-2868.
A) Latencies for the object selective N200 and
latencies for the P200 are highly
correlated. B) and C) P200 amplitudes
normalized at the object selective N200
Faces Scr F Scr W Words Flowers
Words Scr W Scr F Faces Flowers
4
Allison, T., Puce, A. McCarthy, G. (2002).
Category-Sensitive Excitatory and Inhibitory
Processes in Human Extrastriate Cortex. Journal
of Neurophysiology, 88, 2864-2868.
5
Allison, T., Puce, A. McCarthy, G. (2002).
Category-Sensitive Excitatory and Inhibitory
Processes in Human Extrastriate Cortex. Journal
of Neurophysiology, 88, 2864-2868.
FIG. 3. Model of electrogenesis of N200 and P200
ERPs. N200 is the surface recording of excitatory
depolarization of apical dendrites of layer 3 and
4 pyramidal cells. P200 is the surface recording
of inhibitory hyperpolarization of apical
dendrites due to recurrent collateral
(illustrated) or another form of lateral
inhibition. Current flows shown are extracellular
and generate ERPs by synchronous excitation or
inhibition of populations of such cells.
6
Summary of the Results of Allison, Puce,
McCarthy, (2002) R E S U L T S Recordings
made from the inferior surface of
occipitotemporal cortex reveal several patterns
of responsivity. Most electrodes in this region
record no, or small undifferentiated, ERPs to all
categories of stimuli. At approximately 25 of
sites that generated a category-specific N200,
other categories of stimuli generated small
N200s, suggesting that the active cells were
responsive primarily to the preferred stimulus
(faces in the example of Fig. 1A) but were also
slightly responsive to other categories of
stimuli. At other category-specific N200 sites
(approximately 25 of the total), preferred
stimuli (words in the example of Fig. 1B) evoked
an N200, whereas non-preferred stimuli evoked
little or no measurable activity in the latency
range of N200, suggesting that the active cells
responded only to preferred stimuli. D I S C U
S S I O N This study demonstrates that patches of
human extrastriate cortex that generate N200 ERPs
to preferred stimuli often generate P200 ERPs to
nonpreferred stimuli. What is the
electrophysiological basis of these two types of
ERPs and what functionality do they imply? The
initial negativity generated in primary sensory
cortex by an afferent stimulusreferred to as the
primary negativity in the older literature (see
for example Towe 1966)is thought to reflect the
excitatory depolarization of apical dendrites of
pyramidal cells (reviewed by Creutzfeldt and
Houchin 1974 Schlag 1973 Wood and Allison
1981). Recent current source density analysis in
monkey visual cortex supports the older
conclusion by demonstrating current sinks in
apical dendrites after visual stimulation (Mehta
et al. 2000). The apical dendritic depolarization
recorded here as N200 is evoked either by direct
synaptic activation of dendrites or by
backpropagation from the soma (Stuart et al.
1997). If this conclusion is correct, then it
follows that P200 likely reflects hyperpolarizing
inhibition of the same population of apical
dendrites and hence reflects a modulatory
inhibition of cells that prefer a particular
category of stimuli (such as faces) by another
population of cells that prefer a different
category of stimuli (such as words). This model
of electrogenesis is illustrated schematically in
Fig. 3. The simplest mechanism of inhibition
consistent with the data is a recurrent
collateral inhibition, as illustrated in Fig. 3.
7
Recognition Positivity Episodic and semantic
Memory

• The ERP old-new effect consists of two
  components
• The 300-500 ms component is related to
  familiarity and termed FN400 old/new component,
  because of ist similarity with the N400. However,
  the FN400 is often more frontally distributed
  than the centro-parietal N400 which is typically
  observed in studies of language.
• The 400-800 ms component is recollection related
  and termed parietal old/new component. It is
  associated with the recollection of specific
  information such as study modality, speakers
  voice, and temporal source.

8
The ERP old-new effect consists of two
components the frontal FN400 and parietal P3
-7.5
Fz
-7.5
Pz
-5.0
-5.0
FN400 old/new effect
P3 old/new effect
-2.5
-2.5
New
0.0
0.0
New
2.5
2.5
Old
5.0
5.0
Old
7.5
7.5
-100.0
0.0
100.0
200.0
300.0
400.0
500.0
600.0
700.0
800.0
ms
-100.0
0.0
100.0
200.0
300.0
400.0
500.0
600.0
700.0
800.0
ms
Data from continuous recognition task Klimesch e
al. (2005)
9
Fig.A
From Kutas, M., Federmeier, K. D. (2000).
Electrophysiology reveals semantic memory use in
language comprehension. Trends in Cognitive
Sciences, 4 (12), 463-470.
10
Fig.A

• The influence of plausibility and memory
  organization on the N400 response to words in
  sentences. EEG was recorded from 26 scalp
  electrodes (see head icon) as 18 participants
  read sentences, like the example shown here, for
  comprehension. Sentence-final target words
  included
• expected exemplars, the highest cloze probability
  completions for the sentence contexts (e.g.
  palms)
• within-category violations, unexpected (cloze
  probability ,0.05) and implausible (as assessed
  by plausibility ratings) completions that came
  from the same basic level semantic category as
  the expected exemplars (e.g. pines) and
• between-category violations, unexpected and
  implausible completions that came from a
  different (but related) semantic category (e.g.
  tulips).
• Across the experiment all items appeared in all
  target conditions, although a given participant
  saw each only once. Data from a representative
  site over the right, medio-central part of the
  head is shown (indicated by the filled circle on
  the iconic head). All unexpected items elicited
  increased negativity between 250500 ms
  post-stimulus onset (N400) relative to the
  expected exemplars (solid line). However, despite
  equivalent cloze probabilities and plausibility
  ratings, the N400 response to the two unexpected
  items differed as a function of their semantic
  similarity to the expected completions.
  Within-category violation (dashed line), which
  shared many semantic features in common with the
  expected exemplars, elicited smaller N400s than
  did between-category violations (dotted line),
  which had less semantic feature overlap. The
  results suggest that plausibility alone does not
  determine the amplitude of the N400 response to
  words in sentences semantic memory organization
  also plays an important role in determining the
  facility with which the brain processes meaning
  information on-line.

11
Fig. B
Build up of contextual constraint
Schwarz Weiss Vogel Spatz Vogel
Pinguin Ente Blatt
12
Kutas, M., Federmeier, K. D. (2000).
Electrophysiology reveals semantic memory use in
language comprehension. Trends in Cognitive
Sciences, 4 (12), 463-470.
Fig. B
Factors influencing the N400 response. N400
amplitudes are influenced by a number of
different factors, several of which are shown
here at a right-hemisphere site approximately
over Wernickes area (homologue). The N400 is
highly sensitive to semantic (though not just
semantic) relationships of various kinds. (a)
Incongruous words elicit large N400 amplitudes
relative to words that are congruous in their
context, whether these items occur mid-sentence
or in sentence final position. As shown in (c),
this effect can observed in all modalities,
including written and spoken words, and line
drawings (here, all using the same experimental
material). (b) The N400 is similarly sensitive to
varying degrees and types of semantic
relationships in more minimal contexts, including
word pairs. Shown are responses to highly
constrained antonyms (e.g. the opposite of black
WHITE), high typicality category members (e.g. A
type of bird ROBIN), lower typicality category
members (e.g. A type of bird TURKEY) and to
unrelated/mismatched items. (d) Midsentence words
that are repeated in on-going text and show
reduced N400 amplitudes, as do mid-sentence words
that are more frequent in the language in general
(e). The amplitude of the N400 also reflects the
build-up of contextual constraint over the course
of a sentence (f). Not shown here, the ERP to a
word during the N400 epoch (200500 ms) is also
sensitive to relationships at the level of
orthography, phonology and morphology (reviewed
in Ref. 61).
13
Example for recognition positivity Example from
Rugg Wilding (2000)
(a) Recognition memory task
(b) Semantic classification task
Fig. 2. ERP waveforms (averaged over 16 subjects)
from left and right parietal sites (LP and RP) to
new and old words during memory and
classification tasks. The ERPs in the recognition
memory task (a) have been collapsed over correct
and incorrect judgements so as to permit a direct
comparison with the waveforms obtained during the
semantic classification task (b), when no
segregation according to recognition accuracy is
possible. The prominent, left-lateralized
difference between the ERPs elicited by old and
new words in the recognition task is virtually
absent in the semantic task, despite the use of
equivalent encoding tasks, study-test intervals,
and test items. The data are a subset of those
reported originally by Rugg et al.29
14
Curran, T. (2003). Using ERPs to dissociate
recollection from familiarity in picture
reconition. Cognitive Brain Research, 15, 191-205
15
Curran, T. (2003). Using ERPs to dissociate
recollection from familiarity in picture
reconition. Cognitive Brain Research, 15, 191-205
16
Curran, T. (2003). Using ERPs to dissociate
recollection from familiarity in picture
recognition. Cognitive Brain Research, 15, 191-205
Studied yes F R
Similar yes F
17
Fernández, G. (1999). Real-Time Tracking of
Memory Formation in the Human Rhinal Cortex and
Hippocampus. Science, 285 (9), 1582-1585
18
Fernández, G. (1999). Real-Time Tracking of
Memory Formation in the Human Rhinal Cortex and
Hippocampus. Science, 285 (9), 1582-1585
19
Fernández, G. (1999). Real-Time Tracking of
Memory Formation in the Human Rhinal Cortex and
Hippocampus. Science, 285 (9), 1582-1585
Figure Legend to previous page
20
Fernández, G. (1999). Real-Time Tracking of
Memory Formation in the Human Rhinal Cortex and
Hippocampus. Science, 285 (9), 1582-1585
21
Fernández, G. (1999). Real-Time Tracking of
Memory Formation in the Human Rhinal Cortex and
Hippocampus. Science, 285 (9), 1582-1585