Face perception in humans

N170 is larger in amplitude and shorter in latency for an upright face than the other objects （Bentin et al... 2M to Eyes is longer in latency and larger in amplitude → The whole face is

Many things look like a face

fMRI in patients with prosopagnosia

who cannot recognize faces

Fusiform gyrus is activated to

face in a normal subject (NH),

but no response in 3 patients with prosopagnosia (AV, GA, RP)

A: Primary visual cortex (V1), B: Fusiform gyrus

C: MT/V5, D: Superior temporal sulcus (STS), E: Amygdala

Important regions for face perception

Amygdala is important to recognize face expression

Amygdala is

activated to

face expression,

in particular, to fearful and sad faces

A: Primary visual cortex (V1), B: Fusiform gyrus C: MT/V5, D: Superior temporal sulcus (STS),

E: Amygdala Important regions for face perception

look at face,

in particular eyes

In patients with

autism (b), activities

in fusiform gyrus are smaller

than

normal

subject (a)

Face perception and recognition

1 MEG and EEG responses elicited by viewing static faces and eyes

2 Development of face perception and

recognition

3 Face inversion effect

4 Subliminal effect on face perception

MEG machine in our Institute (whole-head type, 306 channels

Face perception and recognition

1 MEG and EEG responses elicited by viewing static faces and eyes

2 Development of face perception and

recognition

3 Face inversion effect

4 Subliminal effect on face perception

 Negative component peaking at 170 msec

( Rossion et al 1999; Watanabe, Kakigi et al 1999a,b, 2001, 2003; Honda

et al 2008; Sagiv & Bentin, 2001; Yovel et al 2003, )

Face specific EEG component

(MEG component is 2M)

N170

N170 is larger in amplitude and shorter in latency for an upright face than the other

objects （Bentin et al 1996; Itier & Taylor, 2004）

(Itier & Taylor, 2004)

N170 is easily changed by how a face is recognized

(Horovitz et al 2004; Linkenkaer-Hansen et al 1998)

(Horovitz et al., 2004)

N170

Face-specific N170 (2M) component

Cooperative study with Yale University

Our Dept: MEG, Yale: fMRI

(Effect of Eyes)

Duration: 250 msec, ISI: 1800 – 2300 msec

60 different faces were shown to avoid a habituation

Watanabe et al.: Cogn Brain Res, Neuroreport, 1999

Face with

opened eyes

(1)

Face with Closed eyes

(2)

Eyes

(3)

Scrambled face

(4)

Hand

(5)

2M component is specific for faces and eyes

No difference between opened and closed eyes

N170

2M to Eyes is longer in latency and larger in

amplitude → The whole face is recognized first but Eyes is more impressive

(Watanabe et al , NeuroReport: 1999)

N170

Fusiform gyrus

Right hemisphere dominance

fMRI results using the same stimuli

recorded at Yale University

(Puce et al J Neurophysiol, 1995)

Face perception and recognition

1 MEG and EEG responses elicited by viewing static faces and eyes

2 Development of face perception and

recognition

3 Face inversion effect

4 Subliminal effect on face perception

Face perception in infants using near-infrared spectroscopy (NIRS)

 NIRS measures cerebral blood flow like fMRI,

although its spatial resolution is much lower than fMRI

Collaborative study with Prof Yamaguchi,

Chuo University, Tokyo, Japan

Otsuka et al.: First study ; 2007

Nakato et al.: Profile face perception ; 2009

Nakato et al.: Mother’s face perception ; 2010 Honda et al.: Scrambled face perception ; 2010 Nakato et al,: Face expression ; 2010

Ichikawa et al.: Biological motion ; 2010

Kobayashi et al.: Face adaptation ; 2011

Kobayashi et al.: Acrimbold face ; 2011

Ichikawa et al.: Effect of eyes ; 2014

NIRS study in infants

 This was the first study to clarify that

5-month-old infants can already differentiate an upright face from objects and an inverted face using neuroimaging methods

(Otsuka, Kakigi et al.: Neuroimage, 2007)

Awake infants (5 - 8 months)

Experimental paradigms

Object

Baseline Upright Face Test Inverted Face Test

Objects

Upright faces

Inverted faces

Object Baseline

(>10 sec )

Recordings

Total hemoglobin in response to faces

Upright face>Inverted face

in the right hemisphere

Tony Blair illusion Anstis ( Perception, 2005 )

It is difficult to recognize eyes and

faces, when whites and colors (blacks in Asians) of eyes are reversed

Humans are the only primate that has white sclera, which contrasts with the

darker colored iris (Kobayashi & Kohshima, 1997 ） ．

(Kobayashi & Kohshima, 1997, 2001)

Clear contrast by whites and colors of eyes

is specific to humans

Do infants recognize Tony Blair Illusion?

・Stimulus

Baseline

Vegetables (14 sec)

Normal eyes (7 sec)

Hemodynamic changes

Clear response was found only to normal eyes

Normal eyes Reversed eyes

Left hemisphere Right hemisphere

Face！

Probably, infants recognize the face by looking at eyes If eyes are not normal, infants do not feel that it is a face

Not face…

Probably, infants recognize the face by looking at eyes If eyes are not normal, infants do not feel that it is a face

Arcimboldo’s funny face

(Kobayashi et al.: 2011,)

Giuseppe Arcimboldo (Italy, 1527-1593)

Vegetables in a vase?

Arcimboldo’s funny face with vegetables

(Kobayashi et al 2011, Frontiers in Human Neuroscience)

Giuseppe Arcimboldo (Italy, 1527-1593)

Old man with a hat?

Infants aged 8 months realize that this is a

face!!

Face perception and recognition

1 MEG and EEG responses elicited by viewing static faces and eyes

2 Development of face perception and

recognition

3 Face inversion effect

4 Subliminal effect on face perception

Face Inversion Effect

Thatcher illusion

Both left and right inverted faces looks similar

But, the eyes and mouth of the right face are different from the left when upright

Face Inversion Effect

(Thatcher illusion)

Face inversion effect

Psychology: Reaction time is delayed and the correction rate is reduced for inverted figures, particularly for face

EEG: Latency is delayed but the amplitude becomes larger for an inverted face

fMRI: BOLD signals become larger for

an inverted face

Inversion effect is very large for face than objects

fMRI study for face inversion effect

 Matsuyoshi D, Morita T, Kochiyama T, Tanabe

Focusing on a mechanism of larger

amplitude of face inversion effect

delayed recognition task

dynamic causal modeling | DCM

inverted

dynamic causal modeling | DCM

dynamic causal modeling | DCM

• When looking at upright face, only selective

face-specific areas are activated Therefore, it is easy

to recognize it

• When looking at inverted face, many areas are

activated and connections between them are

strong Therefore, it is not easy to recognize it

Probably, inverted face is recognized as “Face & Object”, and BOLD signals for inverted face

become larger due to a summation of activities

Mechanisms of face inversion effect

Development of face perception in

children

Subjects : 148 healthy children between 4

and 15 years old (about 15 for each age)

Stimuli : Upright face, inverted face, Eyes

Electrodes : 15 sites on the scalp

Miki et al: Frontiers in Human Neuroscience, 2015

Analysis of face-specific component (N170)

at 4 representative ages, 6, 10 and 14 years old, and adults

In adults, the face-inversion effect

is clearly recognized (long and large N170 to the inverted face) N170 to Eyes is larger than

Face, but it is longer in latency

Analysis of face-specific component (N170)

At 6 years old, Amplitude is very large, particularly to Eyes

No significant difference Between upright and inverted

Analysis of face-specific component (N170)

At 10 years old, N170 showed double peaks, but such s phenomenon

disappeared at 14 years old

Analysis of face-specific component (N170)

At 14 years old, N170 was almost the same

as that in adults

Face perception and recognition

1 MEG responses elicited by

viewing static faces and eyes

2 Development of face perception and

recognition

3 Face inversion effect

4 Subliminal effect on face perception

Subliminal effect on face perception

Face, Letter, Dots and Star are shown for a short period in the video of rotating pot

Three different durations of

intermittent stimuli

Subthreshold : 16 msec

Subjects cannot see it (subliminal)

Intermediate: 32 msec

Subjects can see something,

but cannot determine what it is

Suprathreshold: 48 msec

Subjects can see what it is

Notice: Due to a limitation of time resolution of

PowerPoint, the video moves much slower than the real speed, at about a half

EEG study

New methods for subliminal stimulation

COS: Color-opponent subliminal stimulation

using red, green and yellow

６ Hz

Hoshiyama et al.: Human Brain Mapping, 2006

100 Hz

Hoshiyama et al.: Human Brain mapping, 2006

results are complicated

 Please read our papers to know the detailed results Hoshiyama M, Kakigi R: Human Brain Mapping 2006, Neurosci Lett 2006

Collaborators

NIPS

Shoko Watanabe, Kensaku Miki

Yukiko Honda , Emi Tanaka

Yumiko Otsuka, Emi Nakato,

Megumi Kobayashi, Masami Yamaguchi

Thank you very much

for your attention

Members of my department