Post on 31-Mar-2015
Syntactic learning in non-human primates and neuroimaging of evolutionary precursors to language
Matthew G. Collison
Laboratory for Comparative NeuropsychologyInstitute of Neuroscience
Newcastle University
Where are the evolutionary precursors to human language in the primate brain?
Old World Monkeys (Rhesus Macaque)
25 million years
Humans
8 million years
New World Monkeys (Cotton Top Tamarin)
Great Apes (Chimpanzee)
35 million years
From what did human language evolve?
Syntax: What is it and how do we study it in nonhuman animals?
Syntax is a key components of human language: “the ability to understand the sequence (grammar) of words in a sentence” Very difficult to study in nonhuman species.
However the core computations of syntactic processing can be studied in nonhuman animals using artificial grammars.
Artificial-language (syntactic) learning in monkeys
Grammatical
Ungrammatical Grammatical
Ungrammatical
Fitch & Hauser 2005, Science
Finite State Grammar
Phrase Structure Grammar
%Look
s
Another example: Infants and tamarins learning a different type of “grammar”Saffran et al., Cognition 2008
InfantsTamarins
Old World Monkeys (Rhesus Macaque)
25 million years
Humans
8 million years
New World Monkeys (Cotton Top Tamarin)
Great Apes (Chimpanzee)
35 million years
?
Subclass associations used in word languages
Subclass (Male) Words used Subclass (Female) Words used A1 Biff B1 hepA2 Cav B2 lumA3 Klor B3 pell A4 Dupp B4 lokeA5 Jux B5 pilk
Rhesus macaque experiment
Familiarisation Phase
Test Phase ABAB- A2A3B3B2 A1A2B2B1 A4B5A3B2 AABB- A1B1 A3B3 A2B2A3B3 A2A1B3B5
BBAA- B3B1A1A3 B3B2A2A3 B3B5A2A4
BABA- B2A2B3A3 B4A4B2 A2 B3B1A2A5
Prediction: Double Dissociation
Macaques exposed to FSG will consider PSG sequences as more interesting to look at, but if they were exposed to PSG the opposite effect is predicted.
% looks
Behavioural Results
A) Experiment 1 – Familiarisation to PSG B) Experiment 2 – Familiarisation to FSG
PSG
PSG
The human language regions respond to artificial grammars
Diffusion Tensor Imaging - Connectivity
Friederici 2006
Macaque fMRI: Potential ‘syntactic-learning’ network
PSG Familiarisation
Threshold = 0.01
FSG Familiarisation
Threshold = 0.01
X = 53Y = 85.5
Z = 22
X = 39Y = 84.5
Z = 20
Striatum (implicit learning system)
Dorso-lateral frontal cortex (possibly Broca’s area)
Conclusions
Rhesus Macaques are capable of learning a more elaborate grammar (both FSG and PSG) than tamarins.
fMRI responses to the grammatical sequences shows at least 2 sites as part of the potential ‘syntactic-learning’ network that may have evolved to support language in humans.
Precursor to Statistical learning
Precursors to Syntactic grmmar
Future work to be done
How much more can rhesus macaques learn.
Further fMRI to replicate/support or extend the observations here.
What are the neuronal mechanisms underlying syntactic processing?
InfantsA1A2A3B3B2B1
TamarinsABAB
Old World Monkeys (Rhesus Macaque)
25 million years
Humans
8 million years
New World Monkeys (Cotton Top Tamarin)
Great Apes (Chimpanzee)
35 million years
Evolutionary development of language
Rhesus MacaqueAABB