2/5/2013 Spontaneous Synchronization of Arm Motion Between Japanese - - PDF document

2/5/2013 1 Spontaneous Synchronization of Arm Motion Between Japanese Macaques

Edward Kim and Daniel Acker

Japanese Macaque

• Division of Nature

Publishing Group

• Open-access,
• nline
• No impact factor

(started in 2011)

Laboratory for Adaptive Intelligence, RIKEN Brain Science Institute

• Naotaka Fujii
• M.D. in Ophthalmology, Tohoku University
• Ph.D. in Physiology, Tohoku University
• Lab Head, Lab for Adaptive Intelligence,

RIKEN Brain Science Institute

• Professor, Tokyo University
• Primary interests: Social brain function,

Brain machine interface

• supervised project, provided ideas
• Yasuo Nagasaka
• Research Scientist, RIKEN BSI
• designed experiment, constructed

apparatus, developed computer programs, analyzed data

Laboratory for Adaptive Intelligence, RIKEN Brain Science Institute

• Zenas Chao
• Ph.D. in Biomedical Engineering,

Georgia Institute of Technology

• Research Scientist, RIKEN BSI
• Analyzed data
• Tomonori Notoya
• Technical Staff, RIKEN BSI
• Took care of monkeys, conducted

experiments

• Naomi Hasegawa
• Doctor of Veterinary Medicine
• Research Specialist, RIKEN

BSI

• Took care of monkeys, conducted

experiments

2/5/2013 2

RIKEN

• Independent practical and

basic research institution

• Mostly funded by the

Japanese government

• Has employed multiple

Nobel laureates

• Hideki Yukawa (Physics

1949)

• Shinichiro Tomonaga

(Physics 1965)

• Ryoji Noyori (Chemistry

2001)

Coordination

• Behavioral changes that occur continuously

during social interaction

Discussion Question: What are some examples of

coordination in non-human species?

Some Examples

Schooling in fish. Flocking in birds. Flash coordination in fireflies. Facial imitation in infant primates

______________________________________ Humans lifting heavy furniture. Humans playing music. Lots of other human activities: Dance. Assembly line work. Military formations. Etc.

Intentional vs. Spontaneous Coordination

• Intentional:
• action oriented
• requires recognition
• Spontaneous:
• not goal-oriented
• unconscious
• does not engage higher cognitive processes

Value of Spontaneous Synchronization

• Smoothes conversation
• Ex. Unconscious mimicry increases in the socially excluded,

perhaps as a subconscious attempt to recover from exclusion

• Facilitates building of social rapport
• Ex. In student teacher pairings, self-reported relationship

strength was correlated with independently assessed increased movement synchronization

• May be important for the development of facial imitation
• Mother's pay more attention to imitative infants

First Animal Model of Spontaneous Synchronization

• Intentional, learned synchronization has been

analyzed in macaques and other animals

• Neural circuitry studies included
• No previous controlled model of spontaneous

synchronization

2/5/2013 3

Training

• 3 male macaques (B, C,

and T)

• Trained to press two

buttons repeatedly and alternately with one hand

• Individually trained

Intentional synchronization is unlikely during later paired trials because it takes a long time to train for intentional synchronization (up to a year)

Training Cont.

• Initially, both buttons were

illuminated, and the monkey could press either

• ne
• The LED on the pressed

button turned off, the monkey then pressed the

• ther
• Button presses were

accompanied by short sounds

• Training was complete when

the monkey pressed the buttons 30 - 36 times with no pauses longer than 5s

• After a successful trial, a

chime was played, and the monkey was rewarded with food

Test 1

• Monkeys were paired
• Delay between button

presses between monkeys (ΔtXY) and button presses per second were measured

• Rewards were provided to

both monkeys at the same time regardless of degree of synchronization

• 90 trials over 3 days

Time Locked Synchronization

X axis is delay (ms)

Harmonic Series

• A harmonic is an

integer multiple of a fundamental number

• Ex. 4, 8, 12, 16, 20,

24, 28, 32, 36, etc.

Harmonic Rate Synchronization and Partner Dependence

2/5/2013 4

Test 2

• vMonkey simulated a

partner

• Assembled from video of

monkey T

• vMonkey speed was

adjusted twice per trial as dictated by one of two paradigms

• Fast-slow-fast (FSF)
• Slow-fast-slow (SFS)
• 10 trials per condition per

day

Harmonic Adjustment toward Synchronization

Targets:

• SFS: 1.9 Hz – 3.7 Hz – 1.9 Hz
• FSF: 3.7 Hz – 1.9 Hz – 3.7 Hz

Graphic Representations of Data

Harmonics

• f S-Post

Target

Test 3

• vMonkey, constant speed (2.8 Hz)
• Differences in BP speed and synchrony in:

Auditory-only (A) Visual-only (V) Auditory + Visual (AV)

Auditory/Visual Effects: BP Speed Auditory/Visual Effects: Synchrony

2/5/2013 5

Auditory/Visual Effects: Synchrony Major Conclusions

Test 1: When paired, monkeys synchronized their BP and

adjusted their BP speed to the closest harmonic of their partner's

Test 2: When vMonkey changes speed, the subject adjusts to

match the nearest harmonic of vMonkey's speed

Test 3: Different stimulus modalities did not affect BP speed,

but A+V was required for synchronization (or at least V)

Further Study 1: Clinical Applications

• Social synchronization must be automatic and general for

use in constantly changing environments in the wild

• BP task illustrates generality with synchronization during

unnatural behavior

• Autistic children have difficulty responding to social cues
• BP task could quickly assess autism symptoms

Further Study 2: Brain Regions

• Mirror System is activated both when

performing and observing the same action

• Ventral premotor cortex
• Projects directly to the brain stem

(may be involved in involuntary motor function

• Rostral region of the inferior parietal

lobule

• Damage to this region can cause

echopraxia and echolalia

• Possibly caused by lack of

inhibition to the cortex

Further Study 2: Cont.

• Future experiments would monitor multiple

brain regions during the same behavioral tests

• The most important finding: A behavioral

paradigm that can be used as a basis for experiments exploring the neural mechanisms behind spontaneous social synchronization

Questions or Comments?