scholarly journals Stable Encoding of Task Structure Coexists With Flexible Coding of Task Events in Sensorimotor Striatum

2009 ◽  
Vol 102 (4) ◽  
pp. 2142-2160 ◽  
Author(s):  
Yasuo Kubota ◽  
Jun Liu ◽  
Dan Hu ◽  
William E. DeCoteau ◽  
Uri T. Eden ◽  
...  
Keyword(s):  
Activity Patterns ◽  
Task Structure ◽  
Sensory Stimuli ◽  
Stimulus Response ◽  
Flexible System ◽  
Fine Grain ◽  
Clinical Syndromes ◽  
Habitual Behavior ◽  
The Stability ◽  
Dual Forms

The sensorimotor striatum, as part of the brain's habit circuitry, has been suggested to store fixed action values as a result of stimulus-response learning and has been contrasted with a more flexible system that conditionally assigns values to behaviors. The stability of neural activity in the sensorimotor striatum is thought to underlie not only normal habits but also addiction and clinical syndromes characterized by behavioral fixity. By recording in the sensorimotor striatum of mice, we asked whether neuronal activity acquired during procedural learning would be stable even if the sensory stimuli triggering the habitual behavior were altered. Contrary to expectation, both fixed and flexible activity patterns appeared. One, representing the global structure of the acquired behavior, was stable across changes in task cuing. The second, a fine-grain representation of task events, adjusted rapidly. Such dual forms of representation may be critical to allow motor and cognitive flexibility despite habitual performance.

Attention Theory and Training Research

1987 ◽  
Vol 31 (6) ◽  
pp. 648-651 ◽  
Author(s):  
James G. Connelly ◽  
Christopher D. Wickens ◽  
Gavan Lintern ◽  
Kelly Harwood
Keyword(s):  
Mental Workload ◽  
Open Loop ◽  
Flight Simulation ◽  
Complex Task ◽  
Time Sharing ◽  
Attention Theory ◽  
Stimulus Response ◽  
Training Research ◽  
Complex Training ◽  
The Stability

This study used elements of attention theory as a methodological basis to decompose a complex training task in order to improve training efficiency. The complex task was a microcomputer flight simulation where subjects were required to control the stability of their own helicopter while acquiring and engaging enemy helicopters in a threat environment. Subjects were divided into whole-task, part-task, and part/open loop adaptive task groups in a transfer of training paradigm. The effect of reducing mental workload at the early stages of learning was examined with respect to the degree that subordinate elements of the complex task could be automated through practice of consistent, learnable stimulus-response relationships. Results revealed trends suggesting the benefit of isolating consistently mapped sub-tasks for part-task training and the presence of a time-sharing skill over and above the skill required for the separate subtasks.

scholarly journals Measuring habit formation through goal-directed response switching

2019 ◽  
Author(s):  
David Luque ◽  
Sara Molinero ◽  
Poppy Watson ◽  
Francisco J. López ◽  
Mike Le Pelley
Keyword(s):  
Learning Theory ◽  
Switch Cost ◽  
Time Pressure ◽  
Reward Learning ◽  
Stimulus Response ◽  
Response Switching ◽  
Directed System ◽  
Habitual Behavior ◽  
Reliable Marker ◽  
Translational Models

Reward-learning theory views habits as stimulus–response links formed through extended reward training. Accordingly, animal research has shown that actions that are initially goal-directed can become habitual after operant overtraining. However, a similar demonstration is absent in human research, which poses a serious problem for translational models of behavior. We propose that response-time (RT) switch cost after operant training can be used as a new, reliable marker for the operation of the habit system in humans. Using a new method, we show that RT switch cost demonstrates the properties that would be expected of a habitual behavior: (1) it increases with overtraining; (2) it increases when rewards are larger, and (3) it increases when time pressure is added to the task, thereby hindering the competing goal-directed system. These results offer a promising new pathway for studying the operation of the habit system in humans.

scholarly journals Spontaneous task structure formation results in a cost to incidental memory of task stimuli

2018 ◽  
Author(s):  
Christina Bejjani ◽  
Tobias Egner
Keyword(s):  
Structure Formation ◽  
Structure Learning ◽  
Learning Task ◽  
Underlying Structure ◽  
Task Structure ◽  
Cognitive Demands ◽  
Task Set ◽  
Stimulus Response ◽  
Attention To Task ◽  
Task Sets

Humans are characterized by their ability to leverage rules for classifying and linking stimuli to context-appropriate actions. Previous studies have shown that when humans learn stimulus-response associations for two-dimensional stimuli, they implicitly form and generalize hierarchical rule structures (task-sets). However, the cognitive processes underlying structure formation are poorly understood. Across four experiments, we manipulated how trial-unique images mapped onto responses to bias spontaneous task-set formation and investigated structure learning through the lens of incidental stimulus encoding. Participants performed a learning task designed to either promote task-set formation (by “motor-clustering” possible stimulus-action rules), or to discourage it (by using arbitrary category-response mappings). We adjudicated between two hypotheses: Structure learning may promote attention to task stimuli, thus resulting in better subsequent memory. Alternatively, building task-sets might impose cognitive demands (for instance, on working memory) that divert attention away from stimulus encoding. While the clustering manipulation affected task-set formation, there were also substantial individual differences. Importantly, structure learning incurred a cost: spontaneous task-set formation was associated with diminished stimulus encoding. Thus, spontaneous hierarchical task-set formation appears to involve cognitive demands that divert attention away from encoding of task stimuli during structure learning.

scholarly journals Seasonal plasticity in the adult somatosensory cortex

2020 ◽  
Vol 117 (50) ◽  
pp. 32136-32144
Author(s):  
Saikat Ray ◽  
Miao Li ◽  
Stefan Paul Koch ◽  
Susanne Mueller ◽  
Philipp Boehm-Sturm ◽  
...  
Keyword(s):  
Somatosensory Cortex ◽  
Activity Patterns ◽  
Adaptive Plasticity ◽  
Neural Systems ◽  
Mammalian Brain ◽  
Sensory Stimuli ◽  
Seasonal Plasticity ◽  
Layer 4 ◽  
Life On Earth

Seasonal cycles govern life on earth, from setting the time for the mating season to influencing migrations and governing physiological conditions like hibernation. The effect of such changing conditions on behavior is well-appreciated, but their impact on the brain remains virtually unknown. We investigate long-term seasonal changes in the mammalian brain, known as Dehnel’s effect, where animals exhibit plasticity in body and brain sizes to counter metabolic demands in winter. We find large seasonal variation in cellular architecture and neuronal activity in the smallest terrestrial mammal, the Etruscan shrew, Suncus etruscus. Their brain, and specifically their neocortex, shrinks in winter. Shrews are tactile hunters, and information from whiskers first reaches the somatosensory cortex layer 4, which exhibits a reduced width (−28%) in winter. Layer 4 width (+29%) and neuron number (+42%) increase the following summer. Activity patterns in the somatosensory cortex show a prominent reduction of touch-suppressed neurons in layer 4 (−55%), the most metabolically active layer. Loss of inhibitory gating occurs with a reduction in parvalbumin-positive interneurons, one of the most active neuronal subtypes and the main regulators of inhibition in layer 4. Thus, a reduction in neurons in layer 4 and particularly parvalbumin-positive interneurons may incur direct metabolic benefits. However, changes in cortical balance can also affect the threshold for detecting sensory stimuli and impact prey choice, as observed in wild shrews. Thus, seasonal neural adaptation can offer synergistic metabolic and behavioral benefits to the organism and offer insights on how neural systems show adaptive plasticity in response to ecological demands.

Stimulus-response relations and stability of mechanoreceptor and motor neurons mediating defensive gill-withdrawal reflex in Aplysia

1978 ◽  
Vol 41 (2) ◽  
pp. 402-417 ◽  
Author(s):  
J. H. Byrne ◽  
V. F. Castellucci ◽  
T. J. Carew ◽  
E. R. Kandel
Keyword(s):  
Motor Neurons ◽  
Strain Gauge ◽  
Mantle Cavity ◽  
Moderate Intensity ◽  
Stimulus Response ◽  
Defensive Reflex ◽  
Short And Long Term ◽  
Videotape Recording ◽  
The Stability

1. A weak or moderate-intensity tactile stimulus delivered to the siphon skin of Aplysia californica elicits a defensive reflex withdrawal of the gill and siphon into the mantle cavity. The reflex undergoes both short- and long-term habituation and sensitization and has, therefore, been used as a model system to examine various forms of learning. In this paper we describe studies of the response properties of the sensory and motor neurons of the reflex during repeated stimulation at rates that produce habituation. 2. The sensory neurons are slowly adapting mechanoreceptor cells whose frequency of discharge is a monotonic function of controlled-force punctate stimuli delivered to the skin. The majority of the stimulus-response relations could best be described by exponential functions. 3. We examined the stability of the sensory neuron responses in two ways; with punctate stimuli of varying intensity and with water jets of varying intensity. 4. With repeated punctate stimulation at rates which produce habituation in the intact animal the mechanoreceptor discharge showed no decrement. This stability was observed over a 10-fold range of intensities. 5. Weak or moderate intensity water-jet stimuli to the skin also gave stable responses but stronger stimuli caused the mechanoreceptor response to fatigue. 6. We examined the stability of the motor responses by using intracellular depolarizing current pulses to produce repetitive bursts of action potentials in gill motor neurons while monitoring the gill contractions with a strain gauge, photocell, or videotape recorder. The photocell and strain gauge were alternatively used in the same experiment. Gill contractions monitored with the photocell were stable, whereas those monitored by the strain gauge showed decrement. An independent measure of gill contraction, videotape recording, confirmed the results obtained with the photocell and showed that the gill contractions following repeated intracellular depolarization of the motor neurons were stable.

Thermal Stability of Ultrafine Grains in Al-Fe-Mn-Si Foils Prepared by ARB and Subsequent Rolling

2008 ◽  
Vol 584-586 ◽  
pp. 905-910 ◽  
Author(s):  
Petr Homola ◽  
Margarita Slámová ◽  
P. Sláma ◽  
Miroslav Cieslar
Keyword(s):  
Thermal Stability ◽  
Structural Changes ◽  
High Strength ◽  
Electron Back Scatter Diffraction ◽  
Grain Structure ◽  
Fine Grain ◽  
Hardness Increase ◽  
Cold Rolled ◽  
The Stability ◽  
Thermal Stability Of

Accumulative Roll Bonding (ARB) is a severe plastic deformation process that allows producing ultrafine-grained materials (UFG). UFG sheets exhibit enhanced strength and very fine grain structure. Foils used as fins in heat exchangers have to be very thin but must exhibit high strength combined with relatively high formability. Thus, materials produced using ARB may fulfil the exacting requirements on foil properties for such applications. The thermal stability of Al-Fe- Mn-Si foils produced using ARB and subsequent cold rolling was studied and compared with conventionally cold rolled (CCR) counterparts. The stability was assessed by isothermal annealing in the temperature range from 200 to 450 °C. Electron back scatter diffraction in a scanning electron microscope and transmission electron microscopy examinations of foils microstructure in the deformed and annealed states allowed the monitoring of structural changes. The magnitude of mechanical properties changes due to annealing was evaluated by microhardness measurements. Significant hardness increase was observed after annealing at 200 °C only in the ARB samples and was assigned to an annealing-induced hardening. The CCR foil exhibits higher non-recrystallized fraction and smaller mean lamellae boundary spacing in the temperature interval of 200-250 °C than ARB foils. The annealing at 450 °C results in identical hardness values and fully recrystallized microstructure of all foils, regardless the method used for their manufacturing. However, the ARB samples show higher stability of the refined substructure than their cold rolled counterparts due to continuous recrystallization occurring in the ARB foils.

Vibration Reduction in Large Flexible Systems Through Independent Modal Control

2011 ◽  
Author(s):  
Francesco Braghin ◽  
Simone Cinquemani ◽  
Ferruccio Resta
Keyword(s):  
Acoustic Noise ◽  
Dynamic Performance ◽  
Active Vibration Control ◽  
Spillover Effects ◽  
Flexible System ◽  
Damping Matrix ◽  
Modal Damping ◽  
Active Vibration ◽  
The Stability ◽  
Modal Controller

Many systems have, by their nature, a small damping and therefore they are potentially subjected to dangerous vibration phenomena. The aim of active vibration control is to contain this phenomenon, increasing the damping of the system without changing its natural frequencies and vibration modes. A control of this type can improve the dynamic performance, reduce the vibratory phenomenon (and the resulting acoustic noise) and increase the fatigue strength of the system. The paper introduces a new approach to the synthesis of a modal controller to suppress vibrations in structures: it turns from the traditional formulation of the problem showing how the performance of the designed controller can be evaluated through the analysis of the resulting modal damping matrix of the controlled system. Such analysis allows to evaluate spillover effects, due to the presence of un-modeled modes, the stability of the control and the consequent effectiveness in reducing vibration. The ability to easily manage this information allows the synthesis of an efficient modal controller. Theoretical aspects are supported by experimental applications on a large flexible system.

Effect of Fill Size on the Stability of Barrier Dams

2011 ◽  
Vol 90-93 ◽  
pp. 1373-1382 ◽  
Author(s):  
Zhen Ming Shi ◽  
You Quan Wang ◽  
Jian Feng Chen ◽  
Zu Guang Shang ◽  
Xiao Tao He
Keyword(s):  
Debris Flow ◽  
Failure Mode ◽  
High Speed ◽  
Failure Time ◽  
Coarse Grain ◽  
Fine Grained ◽  
Fine Grain ◽  
Earth Pressures ◽  
Coarse Grains ◽  
The Stability

The fills of barrier dams commonly result from high-speed landslides debris flow. In this paper, four model tests were conducted to study the effect of fill size on the stability of barrier dams. The failure time, failure mode, pore pressures and earth pressures were then observed and analyzed. The results show that barrier dams composed of coarse-grains or well-graded fills are more stable than those composed of fine-grained fills; coarse-grain-dams are more sensitive to the rising of water level than fine-grain-dams; the failure mode of coarse-grain-dams is usually overflowing-erosion and the barrier dams usually fail from the top of dams; the failure mode of fine-grain-dams is sliding and the barrier dams fail initially from the slope downstream.

scholarly journals Dynamic contrast enhancement and flexible odor codes

2017 ◽  
Author(s):  
Srinath Nizampatnam ◽  
Debajit Saha ◽  
Rishabh Chandak ◽  
Baranidharan Raman
Keyword(s):  
Contrast Enhancement ◽  
Antennal Lobe ◽  
Dependent Manner ◽  
Evoked Responses ◽  
Computational Logic ◽  
Behavioral Experiments ◽  
Dynamic Contrast Enhancement ◽  
Sensory Stimuli ◽  
Temporal Features ◽  
The Stability

ABSTRACTSensory stimuli evoke spiking activities patterned across neurons and time that are hypothesized to encode information about their identity. Since the same stimulus can be encountered in a multitude of ways, how stable or flexible are these stimulus-evoked responses? Here, we examined this issue in the locust olfactory system. In the antennal lobe, we found that both spatial and temporal features of odor-evoked responses varied in a stimulus-history dependent manner. The response variations were not random, but allowed the antennal lobe circuit to enhance the uniqueness of the current stimulus. Nevertheless, information about the odorant identity became confounded due to this contrast-enhancement computation. Notably, a linear logical classifier (OR-of-ANDs) that can decode information distributed in flexible subsets of neurons generated predictions that matched results from our behavioral experiments. In sum, our results reveal a simple computational logic for achieving the stability vs. flexibility tradeoff in sensory coding.

scholarly journals Reconstructive Habits: John Dewey on Human Functioning

2018 ◽  
Vol 9 (1) ◽  
pp. 4-24
Author(s):  
David Jaitner
Keyword(s):  
John Dewey ◽  
Human Action ◽  
Human Organism ◽  
Basic Category ◽  
Sensory Stimuli ◽  
Stimulus Response ◽  
Leading Role ◽  
Human Conduct ◽  
Human Functioning ◽  
Key Concepts

The academic strife to parse, investigate and adjust human functioning establishes varieties of at least three key concepts: behavior, action, activity. Depending on the general approach chosen, human functioning is therefore defined in a certain way and in a certain understanding of freedom. Within this paper, the pragmatist considerations of John Dewey (1859-1952) offer a sophisticatedly formulated theory of human functioning that, undoubtedly, takes action-theoretical paths but formulates underlying assumptions in a significantly unusual way. The main focus is to outline the theory in such a way that clearly shows the unusual as part of the usual and the usual as part of the unusual. For this purpose, the first section defines action as the basic category of Deweyan human functioning where sensory stimuli, registering elements and motor responses play a leading role, but according to Dewey questions the today still popular model of behaviorist psychology, that positions isolated and a-cultural stimulus-response-procedures in the human organism. The second section affirms the theoretical inclusion of deliberative elements that constitute human action, but according to Dewey witnesses their substantial and rather sporadic significance in a predominantly habitual human functioning. The conclusive section outlines the possibilities and limits of transforming habitually inured patterns of human conduct by means of reconstructive habits.

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