Vehicle, process, and hybrid theories of consciousness

Author's responseMartínez-Manrique contends that we overlook a possible nonconnectionist vehicle theory of consciousness. We argue that the position he develops is better understood as a hybrid vehicle/ process theory. We assess this theory and in doing so clarify the commitments of both vehicle and process theories of consciousness.Gerard O'Brien and Jonathan Opi

Intracortical inhibition assessed with paired-pulse transcranial magnetic stimulation is modulated during shortening and lengthening contractions in young and old adults

Abstract not availableGeorge M. Opie, John G. Semmle

Age-related differences in short- and long-interval intracortical inhibition in a human hand muscle

Abstract not availableGeorge M. Opie, John G. Semmle

Age-related differences in pre- and post-synaptic motor cortex inhibition are task dependent

Abstract not availableGeorge M. Opie, Michael C. Ridding, John G. Semmle

Short-term immobilization influences use-dependent cortical plasticity and fine motor performance

Short-term immobilization that reduces muscle use for 8-10h is known to influence cortical excitability and motor performance. However, the mechanisms through which this is achieved, and whether these changes can be used to modify cortical plasticity and motor skill learning, are not known. The purpose of this study was to investigate the influence of short-term immobilization on use-dependent cortical plasticity, motor learning and retention. Twenty-one adults were divided into control and immobilized groups, both of which underwent two experimental sessions on consecutive days. Within each session, transcranial magnetic stimulation (TMS) was used to assess motor-evoked potential (MEP) amplitudes, short- (SICI) and long-interval intracortical inhibition (LICI), and intracortical facilitation (ICF) before and after a grooved pegboard task. Prior to the second training session, the immobilized group underwent 8h of left hand immobilization targeting the index finger, while control subjects were allowed normal limb use. Immobilization produced a reduction in MEP amplitudes, but no change in SICI, LICI or ICF. While motor performance improved for both groups in each session, the level of performance was greater 24-h later in control, but not immobilized subjects. Furthermore, training-related MEP facilitation was greater after, compared with before, immobilization. These results indicate that immobilization can modulate use-dependent plasticity and the retention of motor skills. They also suggest that changes in intracortical excitability are unlikely to contribute to the immobilization-induced modification of cortical excitability.George M. Opie, Alexandra Evans, Michael C. Ridding and John G. Semmle

Investigating TMS–EEG indices of long-interval intracortical inhibition at different interstimulus intervals

Available online 8 August 2016Abstract not availableGeorge M. Opie, Nigel C. Rogasch, Mitchell R. Goldsworthy, Michael C. Ridding, John G. Semmle

Priming theta burst stimulation enhances motor cortex plasticity in young but not old adults

Abstract not availableGeorge M. Opie, Eleni Vosnakis, Michael C. Ridding, Ulf Ziemann, John G. Semmle

Internalizing communication

Carruthers presents evidence concerning the cross-modular integration of information in human subjects which appears to support the “cognitive conception of language.” According to this conception, language is not just a means of communication, but also a representational medium of thought. However, Carruthers overlooks the possibility that language, in both its communicative and cognitive roles, is a nonrepresentational system of conventional signals – that words are not a medium we think in, but a tool we think with. The evidence he cites is equivocal when it comes to choosing between the cognitive conception and this radical communicative conception of language.Gerard O'Brien and Jon Opi

Sins of omission and commission

O'Regan & Noë (O&N) fail to address adequately the two most historically important reasons for seeking to explain visual experience in terms of internal representations. They are silent about the apparently inferential nature of perception, and mistaken about the significance of the phenomenology accompanying dreams, hallucinations, and mental imagery.Gerard O'Brien and Jon Opi

Functional resemblance and the internalization of rules

Kubovy and Epstein distinguish between systems that follow rules, and those that merely instantiate them. They regard compliance with the principles of kinematic geometry in apparent motion as a case of instantiation. There is, however, some reason to believe that the human visual system internalizes the principles of kinematic geometry, even if it does not explicitly represent them. We offer functional resemblance as a criterion for internal representation.Gerard O'Brien and Jon Opi