Lenneberg and Brain Dynamics: Comments on Balari & Lorenzo (2017)

Sergio Balari and Guillermo Lorenzo have a paper in the current volume of Biolinguistics, which is dedicated to celebrating the 50th anniversary of Lenneberg’s Biological Foundations of Language. The paper includes a number of unusual claims about computational approaches to neurobiology which I want to briefly address here.
They begin their discussion of neuolinguistics by claiming that “it is our contention that most self-declared biolinguistic approaches … have systematically misapplied the [Marrian] notion of ‘level’ in their attempts at solving the unification problem [of unifying linguistic computation with neurobiology]”. They claim that the connectome (the set of neural connections) and dynome/oscillome (brain dynamics) “are clearly not levels in any possible sense” purely because there is an ongoing project (that the authors are not involved in) to map how brain regions are dynamically connected. But this project crucially is far from over, and so even though at some point direct connectome-oscillome connections should be made, at the moment they clearly are fundamentally distinct levels of description – unless Balari and Lorenzo can explain how they are unified.
The following four paragraphs proceed to repeat the claim that we do not currently understand neural computation. This is true, but only insofar as a physics paper containing four paragraphs lamenting the lack of a Grand Unified Theory is also true. It is common knowledge in the field that neural computation is not understood, yet there are in fact a number of theoretical attempts to solve this conundrum, which Balari and Lorenzo do not critically engage with but rather dismiss out of hand:
“We raise these issues hopefully not for provoking a paralyzing effect, but to caution against an excessively enthusiastic reading of certain recent proposals concerning the computational character of brain oscillations (e.g., those of Murphy 2015, 2016) which do not seem to have taken into account the complications we just alluded to. To repeat, this is not to deny the potential relevance of brain oscillations in an eventual account of neural computation, but evidence so far is only correlational, in the sense that oscillations do play some role in linguistic tasks (e.g., Lewis et al. 2015, Lewis & Bastiaansen 2015, Ding et al. 2016), but we have so far been unable to disentangle the computational role they purportedly play.”
Had they read the papers they cite, they would have found that Murphy (2016a: 16) provides precisely the kind of analysis they claim is lacking in the field, discussing recent indications that oscillations play a causal role in the perceptual segregation of sound patterns – a topic expanded on in Murphy (2016b) which explores other recent tACS experiments into the theta-gamma code for working memory lending these oscillations a causal role in explaining the physical limitations of cognition. Citing existing work into the causal role of oscillations in behaviour is not an “excessively enthusiastic” thing to do, it is simply a way of providing evidence for one’s claims, a procedure seemingly alien to the authors.
More generally, as Uriagereka has already pointed out, expecting a one-to-one mapping between higher-order computational or psycholinguistic theories and neurobiology is similar to expecting a one-to-one mapping between cosmic background radiation and the Big Bang – certainly possible, but highly unlikely, and not even the goal of the neurolinguist attempting to rebuild our understanding of linguistic computation from the bottom-up.
In short, Balari and Lorenzo claim to provide a bold critique of the oscillation literature but in fact do no such thing.
Posted in Linguistics | Leave a comment

Recursion and Oscillations: Comments on Boeckx (2016) and Goucha et al. (2016)

Cedric Boeckx has a new paper out in the Journal of Neurolinguistics, “A conjecture about the neural basis of recursion in light of descent with modification”. The central thesis is summarised as follows: “I argue that the expansion of the parietal region associated with the globularization of the neurocranium in our species contributed to the transformation of the connection between Broca’s and Wernicke’s region via Geschwind’s territory, and enabled the pairing of evolutionary ancient networks that together became capable of constructing and processing not just sequences, but sequences of sequences”.
Boeckx sets the paper up by claiming that his “conjecture” will be a novel one, writing that recursion “rests firmly on primate cognition and neural circuitry” (as if it could rest on anything else). More precisely, the paper claims that “the neuroanatomical reconfiguration of the parietal lobe brought about by globularization extended the Broca-Wernicke connection (to be precise, its dorsal dimension) into “Geschwind’s territory”, forming a fronto-parieto-temporal circuit that provides the basis for richer representational capacities, viz. recursive capacities”.
As in much of his previous work, Boeckx attempts to contribute a relatively minor additional neuroanatomical detail to an already-existing account. Here, he discusses and agrees with the Friederici-inspired story that the development of the fronto-temporal dorsal stream somehow brought about a shift from single-instance concatenation operations to hierarchically organised sequences. The additional detail Boeckx provides is to claim that the expansion of the parietal lobe – a consequence of a more globularised braincase – served to bring about the strengthening of dorsal stream connections. This in turn resulted in “the pairing of two evolutionary ancient networks (one fronto-parietal, the other fronto-temporal), both of which build and process sequences”. What is not mentioned by Boeckx is that this idea has been expressed in Berwick and Chomsky’s recent book Why Only Us (which I reviewed here), and who were themselves re-articulating the findings of primatologists from the past couple of years. So what we could call the “dorsal-ventral pairing hypothesis” is nothing new. And the story itself says nothing about how the brain actually implements what Boeckx refers to as “the nature of the computation (and algorithm) involved”. It is basically just another version of the intuitive, tempting “cartographic” stories rife in the neurolinguistics literature (e.g. “phonology” is in areas X, Y and Z).
Boeckx goes on to claim that this pairing of two streams (each capable of finite-state computations) “could have the effect of boosting computational possibilities. Instead of operating on one-dimensional sequences, one now operates on two-dimensional, ‘tree’ representations”. Boeckx believes that if the fronto-parietal dorsal stream were to be “combined (integrated) with another sequencing machine, sequences of sequences would naturally emerge as a result”. But this appears to be something of a magic step: Pairing two finite-state machines does not produce a higher-order device, and pairing a sequence with another sequence does not necessarily produce “sequences of sequences”. While it may be true that syntactic labeling plus a form of “spell-out” provides the human-specific features of language, and that both labeling and spell-out can be loosely (but only partly) attributed to the hierarchically organised fronto-parietal structures and the fronto-temporal loop connections to externalisation, the jump from single-instance concatenation to recursion likely required more than the pairing of two sequence processors.
Still, the paper is not without a few attractive ideas, such as the following: “Perhaps the fact that the parietal lobe has long been associated with numerosity … may help us understand why syntactic structures exhibit a spontaneous ‘logicality’ … intimately related to quantification, processed by the fronto-parietal network”. There is almost certainly something to this, and as Boeckx is well aware the field could certainly do with more of these sorts of multidisciplinary gestures.
Boeckx closes by saying that “Eventually, the pairing of the sequence processors discussed here will have to be understood in terms of neural activity (coupled oscillations, as I have argued elsewhere (Boeckx, 2013b; Theofanopoulou and Boeckx to appear)”. The problem here is that Boeckx (2013b) doesn’t so much “argue” that linguistic sequence processing is implemented via oscillations so much as it gestures via citation to independent work on neural oscillations which does all of the arguing. No novel implementational hypotheses are put forward by Boeckx. If I write a paper in which I cite recent studies providing evidence for global warming, it would be somewhat disingenuous to say in a paper published years later: “As I argued in Murphy (2013b), average temperatures on Planet Earth are increasing rapidly and we will have to undergo a radical readjustment in terms of fossil fuel consumption as a result”.
There are some very concrete proposals about the neurocomputational properties of brain waves with respect to language which Boeckx does not discuss, for instance here, here, here and here. There does, however, seem to be much confusion concerning this ‘oscillomic’ approach to language. Goucha, Zaccarella and Friederici (2016), for instance, make the following claim:
“Alternative mechanisms based on brain oscillations have been proposed as a crucial element for the emergence of language (Murphy, 2015b) … However, those mechanisms seem to already be in place in other species. For example, despite the crucial brain expansion that took place in primates and especially humans compared to other mammals, the rhythmical hierarchy of oscillations is mainly kept unchanged (Buzsáki et al., 2013). As Friederici and Singer (2015) pinpoint, the basic neural mechanisms behind cognition through the hierarchical embedding of oscillations are transversal across animals.”
This is a peculiar criticism since in the papers of mine proposing an oscillomic model of language, I cite the same authors as Goucha et al., pointing out that while the hierarchy of brain rhythms themselves may be preserved, it is crucially their cross-frequency coupling relations which are human-specific. Besides, the authors make no attempt to explore the functional roles of the “rhythmical hierarchy of oscillations” in human and animal cognition, and it seems as if simply noting that Friederici and Singer (2015) “pinpoint” to something which is in fact well-known within neuroethology is a sufficient reason to reject any forthcoming linking hypotheses concerning linguistic computation and neural oscillations. I suspect that when reading the source material the authors occasionally engaged in what Sir Walter Scott referred to as the “laudable practice of skipping”.
Boeckx, C. 2016. A conjecture about the neural basis of recursion in light of descent with modification. Journal of Neurolinguistics http://dx.doi.org/10.1016/j.jneuroling.2016.08.003.
Goucha, T., Zaccarella, E., & Friederici, A.D. 2016. A revival of the homo loquens as a builder of labeled structures: neurocognitive considerations. Ms. Max Planck Institute for Human Cognitive and Brain Sciences, Germany.
Posted in Linguistics | 4 Comments

Leaving Tamriel

For the second time in less than a year, the British public have voiced an opinion in direct opposition to the vast majority of established political and economic power. The election of Jeremy Corbyn as Labour leader came against all warnings by all major newspapers, intellectuals, academics and bookies. Today, after an even larger swathe of the establishment backed the Remain camp (three-quarters of the Commons supported it), Britain has voted 17.4m to 16.1m to leave the European Union at a 72% turnout. The position Conservatives, Labour, Liberal Democrats, Greens, SNP and Plaid Cymru adopted was summarily rejected. From London to Newcastle to Birmingham, predicted safe Remain zones turned out to be far less secure.
The sheer force of the 17.4m Leave vote cannot be analysed by simply claiming that some people are racist little Englanders and don’t like foreigners. Only 3.8m voted for UKIP in last year’s general election. It’s particularly depressing to see academics lamenting the vote as purely a victory for reactionary demagogues, ignoring many of the crucial factors influencing the Leave vote (not all 17.4m voters hate immigrants). Many Leave voters, according to serious polling, have alarming and legitimate grievances, but it’s also critical to acknowledge that the Leave vote represents in part a frantic cry against the existing mechanisms of representative democracy, which are neither representative nor democratic. We should be very clear about this point: The EU is a valid target for this resentment, for reasons explained by many over the past few weeks, and it’s no use Remain voters exasperatingly pointing to the EU’s mild environmental protections as some kind of devastating rebuttal of deep-seated working class resentment.
Early this morning, Tim Farron said he was ‘utterly gutted and heartbroken’ by the result, and Richard Branson recently claimed Brexit would make him ‘sad’. In contrast, Corbyn shed no tears but proved himself to be much more in touch with the public than the rest of the political and business world with his mature resolve throughout the referendum and his “7.5” support for the EU, as he put it. It is also to the eternal shame of much of the young, student Left that in its various pro-Remain campaigns it put forward arguments without any genuine acknowledgement of the EU’s monumental failures, things that the Bennite Left and other sectors of the traditional socialist movement in Britain would have pointed to straight away (and in fact did), even if their decision was to ultimately push for Remain. There was zero consideration of the EU’s unique, instrumental role in strengthening far-right forces across its member states. The degree of sheer dishonesty on the part of Remain students, academics and business leaders has frankly been staggering.
That said, many on the Left voted Remain for sensible and justifiable reasons, and the Left now needs to reunite against the common threat of looming xenophobia infiltrating mainstream circles. We should recall that the racist right inhabited both sides of the debate, and anyone who thinks Boris Johnson is any worse than Cameron on immigration is simply kidding themselves. Cameron’s performance on last week’s Question Time revealed as much. The prime minister came out with some of the most vicious anti-immigrant rhetoric imaginable, boasting about his goals for severe migration controls and cheerleading plans to deport any immigrant who doesn’t find work within four minutes of being in the UK.
The divisions in the Tory party become extremely apparent when only shortly after Johnson, IDS, Gove and others signed a letter calling on Cameron to stay on as PM (afraid that their in-party disagreement may have more severe repercussions than they bargained for), the prime minister politely rejected their wishes and promised to resign by October. Theresa May or Johnson seem likely candidates.
The goals for the Left should now be to propose a serious EU-free economic agenda (plans for McDonnell’s People’s Quantitative Easing, for instance, will no longer be deterred by EU law, as I wrote in ‘Another Tamriel is Possible’) combined with a socialist message which resonates with the legitimate anti-EU working class resentment so clearly exposed by this morning’s results. Perhaps more urgently, the Left should rally around a coherent anti-racist, anti-fascist, pro-immigration message against the newly emerging establishment Leave winners: Donald Trump has arrived in Scotland today, not without timely symbolic significance. Demonstrations are also being organised outside Downing Street tonight from 6pm onwards showing solidarity with immigrants amongst other things. The serious amounts of pro-Remain/Leave voting energy need to translate into concrete political action from today onwards. This energy needs to be sustained, with the conviction many on the Left had for the ‘Another Europe is Possible’ campaign needing to be redirected against the forces who orchestrated and directed this referendum from the outset: The fractured, ageing, increasingly isolated Tories.
Posted in Activism, Uncategorized | Leave a comment