Results from our laboratories show clear frequency effects for regularly inflected forms in both German and English. Moreover, there does not seem to be sufficient evidence to treat the -s plural as the default plural in German. Together, these data do not support a dual modular structure of the language faculty.

Recent studies showing that pontine burst cells carry a monocular code for rapid eye movements raise questions about the organisation of signals at more central levels. Evidence that the superior colliculus may also be involved in the coding of movements in depth is reviewed. Recent work showing that the global effect is a property of refixations in 3-D space is another indication that the oculomotor systems for direction and depth are centrally coupled.

What exactly is going on via fornical connections? Aggleton & Brown's target article correctly stresses their importance, but a detailed understanding of their role in memory appears to require fresh research approaches.

Explanatory problems in the philosophy of neuroscience are not well captured by the division between the radical and the trivial neuron doctrines. The actual problem is, instead, whether mechanistic biological explanations across different levels of description can be extended to account for psychological phenomena. According to cognitive neuroscience, some neural levels of description at least are essential for the explanation of psychological phenomena, whereas, in traditional cognitive science, psychological explanations are completely independent of the neural levels of description. The challenge for cognitive neuroscience is to discover the levels of description appropriate for the neural explanation of psychological phenomena.

In their model, Findlay & Walker propose that where and when the eyes move is determined by two relatively independent processing streams. Whereas both saccade direction and amplitude result from a low-level visual analysis of the peripheral visual stimulation, saccade latency results mainly from higher-level processes related to processing of the central information. In the present commentary, reading eye movement data are put forward as evidence against a strict autonomy of “Where” and “When” processing streams. First, saccade direction and amplitude might be modified by high-level processes related to word identification. Second, the direction of a saccade directly affects its latency.

We report an experiment that unambiguously shows an effect of full-form frequency for fully regular Dutch inflected verbs falling into Clahsen's “default” category, negating Clahsen's claim that regular complex words in the default category are not stored.

O'Brien & Opie's theory fails to address the issue of consciousness and introspection. They take for granted that once something is experienced, it can be commented on. But introspection requires neural structures that, according to their theory, have nothing to do with experience as such. That makes the tight coupling between the two in humans a mystery.

Two notions of autonomy are distinguished. The respective denials that psychology is autonomous from neurobiology are neuron doctrines, moderate and radical. According to the moderate neuron doctrine, interdisciplinary interaction need not aim at reduction. It is proposed that it is more plausible that there is slippage from the moderate to the radical neuron doctrine than that there is confusion between the radical neuron doctrine and the trivial version.

Recent studies of the contribution made by the hippocampus to spatial behavior suggest that it plays a role in integrating and double integrating distance and direction information using cues generated by self-movement. This and other evidence that the hippocampus plays a central role in spatial behavior seems inconsistent with proposals that it is primarily involved in episodic memory.

Findlay & Walker give voice to several common lines of thought regarding oculomotor control but do not provide sufficient detail for a critical evaluation of their theory. I argue that arbitrary spatial and temporal saccade metrics can be produced simply by manipulating the initial activation values in their model – values that the authors never specify. This lack of detail makes it difficult to anticipate the model's specific oculomotor behavior, or to compare this behavior to models opting for a more quantitative framework.

O'Brien & Opie do not address the question of the psychotherapeutic role of unconscious representational states such as beliefs. A dilemma is proposed: if they accept the legitimacy of such states then they should modify what they say about dissociation, and if they do not, they owe us an account of why.

I argue for an extension of Clahsen's psycholinguistic paradigm to well-known languages with more complex morphological systems. This would help to address conceptual questions such as the nature of defaults and the way in which syncretisms are coded in the brain.

The German facts are consistent with the hypothesis that the default is the most frequent allomorph. Plural -s is the least frequent allomorph and does not act as a default. There is another way to measure the frequency of perfects in which no single -n allomorph is as frequent as -t. Lexical versus computational components do not correlate with regularity.

According to Gold & Stoljar, one cannot consistently be both reductionist about psychoneural relations and invoke concepts developed in the psychological sciences. I deny the utility of their distinction between biological and cognitive neuroscience, suggesting that they construe biological neuroscience too rigidly and cognitive neuroscience too liberally. Then, I reject their characterization of reductionism. Reductions need not go down past neurobiology straight to physics, and cases of partial, local reduction are not neatly distinguishable from cases of mere implementation. Modifying the argument from unification as reduction, I defend a position weaker than the radical but stronger than the trivial neuron doctrine.

Aggleton & Brown propose that familiarity-based recognition depends on a perirhinal-medial dorsal thalamic system. However, connections between these structures are sparse or absent. In contrast, the perirhinal cortex is connected to midline/intralaminar nuclei. In a human, a lesion in this thalamic domain, sparing the medial dorsal nucleus, impaired familiarity-based recognition while sparing recollective-based recognition. It is thus more likely that the intralaminar/midline nuclei are involved in recognition.

The target article retains the traditional account of saccades as conjugate eye movements. However, recent single-unit recordings of premotor cells in the saccade pathway (excitatory burster neurons [EBNs]) found that they do not encode conjugate eye velocity, but rather, monocular eye velocity. These data argue against the traditional concept of saccades as inherently conjugate. Instead, they suggest a monocular mechanism in the sensorimotor transformation stage of saccade generation. This commentary will discuss the implications of these data for the saccade generation model proposed in Findlay & Walker's target article.

O'Brien & Opie hold that phenomenal experience should be identified with “stable patterns of activation” across the brain's neural networks, and that this proposal has the potential for closing the ‘explanatory gap' between mental states and brain processes. I argue that they have too much respect for the conceivability argument and that their proposal already does much to close the explanatory gap, but that a “perspicuous nexus” can in principle never be achieved.

O'Brien & Opie's admirably sharp hypothesis gains some of its force by ignoring distinctions in murky areas. I attempt to agitate the waters by suggesting that process and vehicle theories are not so different, that classicism can support a vehicle theory, and that several of the key concepts underlying their theory are less clear than depicted. The connection to information I find especially tenuous. Finally, I address the implications of their theory for unconscious thought.

Our target article discussed how emerging knowledge of the physiological processes involved in the control of saccadic eye movements provided the basis for a functional framework in which to understand the programming of such movements. The commentators raised many interesting issues in their varied responses that ranged from detailed discussion of the physiological substrate through issues of saccade control in reading. New evidence at the physiological level demonstrates that some elaborations are needed to the framework we proposed. Most clearly, the spatial selection process operates in a manner different from our suggestion of an increase in activity in the salience map. Some commentators make the interesting and welcome proposal that the functional processes we outline may in fact be implemented with an even more unified physiological substrate (continuity between collicular fixation and build-up cells) than we envisaged. Extensions to the framework are discussed involving the planning of sequential saccades, saccades made in crossmodal situations, the influences of learning and memory, and binocular saccades. We consider carefully the commentaries proposing explicit attentional and/or executive processes in the programming of saccades. We integrate the comments of researchers investigating saccade control in neurological and neuropsychiatric patients and finally discuss whether the framework can account for saccades made in the course of reading.

Clahsen has presented an impressive range of psycholinguistic data from German regular and irregular inflection to support the view that lexical memory and the combinatorial operations of grammar are subserved by distinct mental mechanisms. Most of the data are convincing and important. I particularly applaud Clahsen's effort to extend this lexical/grammatical dichotomy from mind to brain. Here I discuss some problems with the evidence presented by Clahsen in support of a neural lexical/grammatical dichotomy, and offer some additional evidence to reinforce this neural distinction.