scholarly journals Fragmented Spatial Maps: State Abstraction and Efficient Planning from Surprisal

2021 ◽  
Author(s):  
Mirko Klukas ◽  
Sugandha Sharma ◽  
Yilun Du ◽  
Tomas Lozano-Perez ◽  
Leslie Pack Kaelbling ◽  
...  
Keyword(s):  
Spatial Clustering ◽  
Place Cells ◽  
Complex Environments ◽  
Chinese Restaurant Process ◽  
Chinese Restaurant ◽  
Electrophysiological Recordings ◽  
Efficient Planning ◽  
State Abstraction ◽  
Spatial State

When animals explore spatial environments, their representations often fragment into multiple maps. What determines these map fragmentations, and can we predict where they will occur with simple principles? We pose the problem of fragmentation of an environment as one of (online) spatial clustering. Taking inspiration from the notion of a "contiguous region" in robotics, we develop a theory in which fragmentation decisions are driven by surprisal. When this criterion is implemented with boundary, grid, and place cells in various environments, it produces map fragmentations from the first exploration of each space. Augmented with a long-term spatial memory and a rule similar to the distance-dependent Chinese Restaurant Process for selecting among relevant memories, the theory predicts the reuse of map fragments in environments with repeating substructures. Our model provides a simple rule for generating spatial state abstractions and predicts map fragmentations observed in electrophysiological recordings. It further predicts that there should be "fragmentation decision" or "fracture" cells, which in multicompartment environments could be called "doorway" cells. Finally, we show that the resulting abstractions can lead to large (orders of magnitude) improvements in the ability to plan and navigate through complex environments.

Effect of background clutter on neural discrimination in the bat auditory midbrain

2021 ◽  
Author(s):  
Kathryne M Allen ◽  
Angeles Salles ◽  
Sanwook Park ◽  
Mounya Elhilali ◽  
Cynthia F. Moss
Keyword(s):  
Acoustic Scattering ◽  
Object Discrimination ◽  
Complex Environments ◽  
Acoustic Features ◽  
Temporal Separation ◽  
Complex Sounds ◽  
Electrophysiological Recordings ◽  
Background Clutter ◽  
Spatio Temporal ◽  
Neural Underpinnings

The discrimination of complex sounds is a fundamental function of the auditory system. This operation must be robust in the presence of noise and acoustic clutter. Echolocating bats are auditory specialists that discriminate sonar objects in acoustically complex environments. Bats produce brief signals, interrupted by periods of silence, rendering echo snapshots of sonar objects. Sonar object discrimination requires that bats process spatially and temporally overlapping echoes to make split-second decisions. The mechanisms that enable this discrimination are not well understood, particularly in complex environments. We explored the neural underpinnings of sonar object discrimination in the presence of acoustic scattering caused by physical clutter. We performed electrophysiological recordings in the inferior colliculus of awake big brown bats, to broadcasts of pre-recorded echoes from physical objects. We acquired single unit responses to echoes and discovered a sub-population of IC neurons that encode acoustic features that can be used to discriminate between sonar objects. We further investigated the effects of environmental clutter on this population's encoding of acoustic features. We discovered that the effect of background clutter on sonar object discrimination is highly variable and depends on object properties and target-clutter spatio-temporal separation. In many conditions, clutter impaired discrimination of sonar objects. However, in some instances clutter enhanced acoustic features of echo returns, enabling higher levels of discrimination. This finding suggests that environmental clutter may augment acoustic cues used for sonar target discrimination and provides further evidence in a growing body of literature that noise is not universally detrimental to sensory encoding.

scholarly journals Dragonfly Inspired Smart Soft Robot

2020 ◽  
Author(s):  
Vardhman Kumar ◽  
Ung Hyun Ko ◽  
Yilong Zhou ◽  
Jiaul Hoque ◽  
Gaurav Arya ◽  
...  
Keyword(s):  
Environmental Remediation ◽  
Stimuli Responsive ◽  
Complex Environments ◽  
Soft Robots ◽  
Responsive Materials ◽  
Environmental Perturbations ◽  
Integration Strategies ◽  
Soft Actuators ◽  
Harsh Conditions

Recent advancements in soft robotics have led to the development of compliant robots that can exhibit complex motions driven by living cells(1, 2), chemical reactions(3), or electronics(4). Further innovations are however needed to create the next generation of soft robots that can carry out advanced functions beyond locomotion. Here we describe DraBot—a dragonfly-inspired, entirely soft, multifunctional robot that combines long-term locomotion over water surface with sensing, responding, and adaptation capabilities. By integrating soft actuators, stimuli-responsive materials, and microarchitectural features, we created a circuitry of pneumatic and microfluidic logic that enabled the robot to undergo user- and environment-controlled (pH) locomotion, including navigating hazardous (acidic) conditions. DraBot was also engineered to sense additional environmental perturbations (temperature) and detect and clean up chemicals (oil). The design, fabrication, and integration strategies demonstrated here pave a way for developing futuristic soft robots that can acclimatize and adapt to harsh conditions while carrying out complex tasks such as exploration, environmental remediation, and health care in complex environments.

scholarly journals Hippocampal sharp wave-ripples and the associated sequence replay emerge from structured synaptic interactions in a network model of area CA3

2021 ◽  
Author(s):  
Andras Ecker ◽  
Bence Bagi ◽  
Eszter Vertes ◽  
Orsolya Steinbach-Nemeth ◽  
Maria Rita Karlocai ◽  
...  
Keyword(s):  
Place Cells ◽  
Data Driven ◽  
Long Term Memory ◽  
Term Memory ◽  
Cellular Adaptation ◽  
Sharp Wave ◽  
Synaptic Interactions ◽  
Area Ca3 ◽  
Reversed Order

Hippocampal place cells are activated sequentially as an animal explores its environment. These activity sequences are internally recreated ("replayed"), either in the same or reversed order, during bursts of activity (sharp wave-ripples; SWRs) that occur in sleep and awake rest. SWR-associated replay is thought to be critical for the creation and maintenance of long-term memory. We sought to identify the cellular and network mechanisms of SWRs and replay by constructing and simulating a data-driven model of area CA3 of the hippocampus. Our results show that the structure of recurrent excitatory interactions established during learning not only determines the content of replay, but is essential for the generation of the SWRs as well. We find that bidirectional replay requires the interplay of the experimentally confirmed, temporally symmetric plasticity rule, and cellular adaptation. Our model provides a unifying framework for diverse phenomena involving hippocampal plasticity, representations, and dynamics.

scholarly journals Long-term student experiences in a hybrid, open-ended and problem based Adventure Learning program

2010 ◽  
Vol 26 (2) ◽  
Author(s):  
George Veletsianos ◽  
Aaron Doering
Keyword(s):  
Educational Technology ◽  
Elementary School Children ◽  
Learning Experience ◽  
Student Experiences ◽  
Future Research ◽  
Complex Environments ◽  
Learning Program ◽  
Research And Practice ◽  
Adventure Learning

<span>In this paper we investigate the experiences of elementary school children over a two-year period during which they engaged with a hybrid Adventure Learning program. In addition to delineating Adventure Learning experiences, we report on educational technology implementations in ecologically valid and complex environments, while drawing inferences on the design of sustainable and successful innovations. Our research indicates that the Adventure Learning experience over the two-year period was dynamic, participatory, engaging, collaborative, and social. Students eagerly became part of the experience both inside and outside of the classroom, and it quickly became apparent that they saw themselves as valued members of the unfolding storyline that mediated their learning. Our recommendations for future research and practice include a call to evaluate "authenticity," focus on the learner experience and narrative, and consider the interplay between pedagogy, technology, and design.</span>

scholarly journals A Distance-Dependent Chinese Restaurant Process Based Method for Event Detection on Social Media

Inventions ◽  
2018 ◽  
Vol 3 (4) ◽  
pp. 80 ◽  
Author(s):  
Georgios Palaiokrassas ◽  
Athanasios Voulodimos ◽  
Antonios Litke ◽  
Athanasios Papaoikonomou ◽  
Theodora Varvarigou
Keyword(s):  
Social Media ◽  
Event Detection ◽  
Dirichlet Process ◽  
Chinese Restaurant Process ◽  
Chinese Restaurant ◽  
Social Events ◽  
The Social ◽  
Social Event Detection ◽  
Clustering Approach ◽  
Processing Steps

In this paper, we propose a method for event detection on social media, which aims at clustering media items into groups of events based on their textural information as well as available metadata. Our approach is based on distance-dependent Chinese Restaurant Process (ddCRP), a clustering approach resembling Dirichlet process algorithm. Furthermore, we scrutinize the effectiveness of a series of pre-processing steps in improving the detection performance. We experimentally evaluated our method using the Social Event Detection (SED) dataset of MediaEval 2013 benchmarking workshop, which pertains to the discovery of social events and their grouping in event-specific clusters. The obtained results indicate that the proposed method attains very good performance rates compared to existing approaches.

scholarly journals Beyond spikes: Multiscale computational analysis of in vivo long-term recordings in the cockroach circadian clock

2019 ◽  
Vol 3 (4) ◽  
pp. 944-968 ◽  
Author(s):  
Pablo Rojas ◽  
Jenny A. Plath ◽  
Julia Gestrich ◽  
Bharath Ananthasubramaniam ◽  
Martin E. Garcia ◽  
...  
Keyword(s):  
Circadian Clock ◽  
Field Potential ◽  
Dynamic Features ◽  
Pigment Dispersing Factor ◽  
Gamma Frequency ◽  
Accessory Medulla ◽  
Electrophysiological Recordings ◽  
Wide Range

The circadian clock of the nocturnal Madeira cockroach is located in the accessory medulla, a small nonretinotopic neuropil in the brain’s visual system. The clock comprises about 240 neurons that control rhythms in physiology and behavior such as sleep-wake cycles. The clock neurons contain an abundant number of partly colocalized neuropeptides, among them pigment-dispersing factor (PDF), the insects’ most important circadian coupling signal that controls sleep-wake rhythms. We performed long-term loose-patch clamp recordings under 12:12-hr light-dark cycles in the cockroach clock in vivo. A wide range of timescales, from milliseconds to seconds, were found in spike and field potential patterns. We developed a framework of wavelet transform–based methods to detect these multiscale electrical events. We analyzed frequencies and patterns of events with interesting dynamic features, such as mixed-mode oscillations reminiscent of sharp-wave ripples. Oscillations in the beta/gamma frequency range (20–40 Hz) were observed to rise at dawn, when PDF is released, peaking just before the onset of locomotor activity of the nocturnal cockroach. We expect that in vivo electrophysiological recordings combined with neuropeptide/antagonist applications and behavioral analysis will determine whether specific patterns of electrical activity recorded in the network of the cockroach circadian clock are causally related to neuropeptide-dependent control of behavior.

Sign in / Sign up

Export Citation Format

Share Document