Erasing Sensorimotor Memories via PKMζ Inhibition

Sensorimotor cortex has a role in procedural learning. Previous studies suggested that this learning is subserved by long-term potentiation (LTP), which is in turn maintained by the persistently active kinase, protein kinase Mzeta (PKMζ). Whereas the role of PKMζ in animal models of declarative knowledge is established, its effect on procedural knowledge is not well understood. Here we show that PKMζ inhibition, via injection of zeta inhibitory peptide (ZIP) into the rat sensorimotor cortex, disrupts sensorimotor memories for a skilled reaching task even after several weeks of training. The rate of relearning the task after the memory disruption by ZIP was indistinguishable from the rate of initial learning, suggesting no significant savings after the memory loss. These results indicate a shared molecular mechanism of storage for declarative and procedural forms of memory

The Mental Database

This article uses database, evolution and physics considerations to suggest how the mind stores and processes its data. Its innovations in its approach lie in:- A) The comparison between the capabilities of the mind to those of a modern relational database while conserving phenomenality. The strong functional similarity of the two systems leads to the conclusion that the mind may be profitably described as being a mental database. The need for material/mental bridging and addressing indexes is discussed. B) The consideration of what neural correlates of consciousness (NCC) between sensorimotor data and instrumented observation one can hope to obtain using current biophysics. It is deduced that what is seen using the various brain scanning methods reflects only that part of current activity transactions (e.g. visualizing) which update and interrogate the mind, but not the contents of the integrated mental database which constitutes the mind itself. This approach yields reasons why there is much neural activity in an area to which a conscious function is ascribed (e.g. the amygdala is associated with fear), yet there is no visible part of its activity which can be clearly identified as phenomenal. The concept is then situated in a Penrosian expanded physical environment, requiring evolutionary continuity, modularity and phenomenality.Several novel Darwinian advantages arising from the approach are described

Neuroplasticity Subserving Motor Skill Learning

Recent years have seen significant progress in our understanding of the neural substrates of motor skill learning. Advances in neuroimaging provide new insight into functional reorganization associated with the acquisition, consolidation, and retention of motor skills. Plastic changes involving structural reorganization in gray and white matter architecture that occur over shorter time periods than previously thought have been documented as well. Data from experimental animals provided crucial information on plausible cellular and molecular substrates contributing to brain reorganization underlying skill acquisition in humans. Here, we review findings demonstrating functional and structural plasticity across different spatial and temporal scales that mediate motor skill learning while identifying converging areas of interest and possible avenues for future research

The Effects of High-Intensity Acute Exercise on Implicit Memory and Face-Name Explicit Memory

Objective: The majority of previous research evaluate the effects of acute exercise on memory function have focused on explicit memory tasks involving word-list paradigms. For more real-world application, the present experiment evaluates whether high-intensity acute exercise can improve implicit memory function as well as increase one’s ability to remember names associated with faces (face-name paradigm). Methods: A two-arm, parallel-group, randomized controlled intervention was employed. Participants (N=91; Mage= 20 yrs) were randomized into one of two groups, including an experimental group and a control group. The experimental group exercised for 20 minutes on a treadmill at a high-intensity (75% of heart rate reserve), while the control group engaged in a seated, time-matched task. Explicit memory was assessed via a face-name paradigm in which participants encoded and subsequently recalled names that were paired with faces. Implicit memory was evaluated with computerized program involving spatial-temporal integration. Results: The acute exercise group recalled more face-name pairs than the control group (11.16 words vs. 9.79 words), but this did not reach statistical significance (p = .25). There were also no group differences for implicit memory (p =.57).Conclusion: We did not observe convincing evidence that high-intensity acute exercise influences face-name explicit memory or implicit memory function. However, future work on this under-investigated topic is needed. Keywords: Cognition; cognitive function; physical activit

Mental content : consequences of the embodied mind paradigm

The central difference between objectivist cognitivist semantics and embodied cognition consists in the fact that the latter is, in contrast to the former, mindful of binding meaning to context-sensitive mental systems. According to Lakoff/Johnson's experientialism, conceptual structures arise from preconceptual kinesthetic image-schematic and basic-level structures. Gallese and Lakoff introduced the notion of exploiting sensorimotor structures for higherlevel cognition. Three different types of X-schemas realise three types of environmentally embedded simulation: Areas that control movements in peri-personal space; canonical neurons of the ventral premotor cortex that fire when a graspable object is represented; the firing of mirror neurons while perceiving certain movements of conspecifics. ..

Imitation of atypical biological motion in autism spectrum disorders

The aim of the present thesis was to examine imitation of biological motion in adults with autism spectrum disorders. Using a novel behavioural protocol, adults with autism and matched neurotypical control adults imitated models that displayed distinctly different, but biological believable kinematics. In Chapter Two it was observed that adults with autism exhibited low-fidelity imitation of atypical biological motion. In Chapter Three it was observed that when selective-attention instructions were provided, although eye movements recorded during action- observation was similar to controls, imitation of atypical biological motion was still impaired. In Chapter Four across three experiments it was shown that adults with autism exhibit reasonably high-fidelity imitation of atypical biological motion. This was achieved by presenting the to-be-imitated biological models in a fixed presentation structure which is known to facilitate greater integration and consolidation of sensorimotor information. This suggestion was supported by a further study where firstly participants were required to complete a secondary motor task during the inter-trial delay, and when the presentation structure was randomised (similar to Chapters Two and Three) resulting in low-fidelity imitation of atypical biological motion. These findings across the present thesis will be discussed in light of a critical evaluation with respect to current literature on imitation in autism, as well as implications for theoretical accounts of impaired imitation in autism and related sensorimotor control processes. Future considerations and translational research will be discussed, with the intention of offering prospective social rehabilitation protocols in autism

In vivo Observation of the Release of Norepinephrine and In Vivo Optical Studies on the Direct and Indirect Paths of the Striatum

This thesis focuses on my work using optical techniques to study different brain regions in vivo. The ability to optically study neurons and the circuits they comprise in vivo is an important method to better understand their role in the healthy brain and their dysfunction in disease. The first part of my thesis focuses on my work using on a collaborative project using a new optical probe to study norepinephrine synapses in vivo. In this work we were able to observe the effects of amphetamine on norepinephrine release in vivo and observed some evidence of potential silent synapses. I also describe a new method of cranial window surgery I developed for optical imaging. This technique called PHASOR, is faster, and has a higher success rate, than traditional surgical methods. The improvements demonstrated in this new surgical technique may enable more widespread use of optical imaging methods. In the second part of my thesis, I used optical techniques to study the dorsal striatum in vivo in awake behaving mice. The direct and indirect paths of the dorsal striatum play an important role in motor behavior and motor learning. Dysfunction in these paths has been implicated in motor diseases as well as in mood disorders. In this thesis, I provide a review of the anatomy and physiology of the neurons that comprise the dorsal striatum, and the circuits that they form. The next chapters describe my work using optical techniques to record from these neurons in vivo. In my first set of experiments, I recorded from the direct and indirect paths during a behavioral task of anxiety and observed differential firing depending on the anxiety state of the mouse. Finally, in a preliminary set of experiments, I record from the direct and indirect paths during tasks of motor learning. I found that both paths show changes in firing during motor learning and that these changes differ between the dorsolateral and dorsomedial striatum

De Novo Learning of Motor Skills

From playing the piano to driving a car, humans acquire a wide range of motor skills throughout their lifetimes. How are people capable of learning such a wide repertoire of skills? Studies in motor learning have attempted to address this question by examining "adaptation", a trial-by-trial learning mechanism where movements are updated via the reduction of sensory prediction errors. However, a growing body of literature suggests that adaptation alone cannot account for how people learn many real-world skills. It has instead been hypothesized that the brain acquires many new skills by building a new motor controller "de novo". Currently, little is understood about de novo learning as most prior studies of motor learning have focused on investigating adaptation. In this dissertation, we performed a series of experiments to characterize the nature of de novo learned controllers. First, we devised a novel frequency-domain system identification approach to characterize how people learn to compensate for visuomotor perturbations. We used this approach to demonstrate that people learn skills which require continuous movement output—such as riding a bike or juggling—via de novo learning. We then designed a challenging de novo learning task which involved controlling an on-screen cursor using a bimanual mapping. In contrast to many laboratory-based motor learning tasks which can be learned on the timescale of minutes, participants required multiple days of practice to learn the bimanual mapping. In this task, we found that participants' responses to mid-movement perturbations remained limited after four days of practice, suggesting that limitations in one's ability to select appropriate actions may contribute to performance plateaus during learning. Finally, we used the same bimanual mapping to understand how de novo learned skills become habitual. We found that participants' behavior could continue to become more skillful despite the fact that it had already become habitual, suggesting that the emergence of skill and habit are dissociable during learning. Collectively, our results illustrate the behavioral phenomenology associated with de novo learned controllers and highlight the critical role that de novo learning plays when people learn real-world skills

Human-Human Sensorimotor Interaction

We investigated the role of sensory feedback in inter-personal interactions when two co-workers are working together. Twenty-five co-workers completed two isometric finger force production experiments. In Experiment 1, co-workers isometrically produced finger forces such that combined force will match a target force and/or torque under different visual and haptic conditions. In Experiment 2, without participants’ knowledge, each performed the same task with the playback of his/her partner’s force trajectory previously recorded from Experiment 1. Results from both experiments indicated that co-workers performed the task worse in the presence of haptic and visual feedback. Since, in latter as opposed to the former condition, they adopted a compensatory strategy to accomplish the task accurately. Further analysis showed that co-workers achieved the same level of motor performance with similar control strategies, suggesting that they did not work synergistically to achieve better performance, but one co-worker processed another as disturbance when they worked together