Maze Running Research Articles

Quantum walks in spaces with applied potentials

Discrete quantum walks are a universal model of quantum computation equivalent to the quantum circuit model and can be mapped onto quantum circuits and executed using quantum computers. Quantum walks can model and simulate many physical systems and several quantum algorithms are based on them. Discrete quantum walks have been extensively studied, but quantum walks that evolve in spaces in which potentials are applied received little or no attention. Here, we formulate the discrete quantum walk model in one and two-dimensional spaces in which potentials are applied. In this formulation the quantum walker carries a “charge” affected by the potentials and the walk evolution is driven by both constant and time-varying potentials. We reproduce the tunneling through a barrier phenomenon and study the quantum walk evolution in one and two-dimensional spaces with various potential distributions. We demonstrate that our formulation can serve as a basis for applied quantum computing by studying maze running and the motion of vehicles in urban spaces. In these spaces curbs and buildings are modeled as impenetrable potential barriers and traffic lights as time-varying potential barriers. Quantum walks in spaces with applied potentials may open the way for the development of novel quantum algorithms in which inputs are introduced as potential profiles.

Maze running into intumescence: mechanistic aspects in polypropylene

The concept of intumescence was applied to make flame retarded polypropylene (PP). This paper examines two types of intumescence in PP) based on expandable graphite (EG, physical expansion) and on modified ammonium polyphosphate (AP760, chemical expansion). Reaction to fire of PP containing EG and AP760 was first evaluated by cone calorimetry. The incorporation of intumescent additives at relatively low loading (10 wt%) in PP permits the reduction by 70% of pHRR. The mode of action occurs via the formation of an expanded carbonaceous layer in all cases. The protective coating acts mainly as heat barrier in the case of the formulations containing AP760 or as heat dissipater with EG. The incorporation of small amount of EG in PP-AP760 modifies heat transfer in the coating creating a strong anisotropy. Upon expansion graphite worms align normal to the surface increasing the transverse heat conductivity (lower efficiency of the heat barrier) and hence, decreasing the fire performance (decrease by only 30% of pHRR). Kinetic analysis was then performed to quantify the thermal stability of the intumescent systems. It reveals that the intumescent additives do not modify the reactional scheme of the PP thermal decomposition but they increase slightly the thermal stability of the intumescent systems.

Have a Heart: Predictability of Trust in an Autonomous Agent Teammate through Team-Level Measures of Heart Rate Synchrony and Arousal

Have a Heart: Predictability of Trust in an Autonomous Agent Teammate through Team-Level Measures of Heart Rate Synchrony and Arousal

EEG and functional ultrasound imaging in mobile rats

We developed an integrated experimental framework that extends the brain exploration capabilities of functional ultrasound imaging to awake and mobile rats. In addition to acquiring hemodynamic data, this method further allows parallel access to electroencephalography (EEG) recordings of neuronal activity. We illustrate this approach with two proofs of concept: a behavioral study on theta rhythm activation in a maze running task and a disease-related study on spontaneous epileptic seizures.

Selective Effects of Dopamine Depletion and L-DOPA Therapy on Learning-Related Firing Dynamics of Striatal Neurons

Despite evidence that dopamine neurotransmission in the striatum is critical for learning as well as for movement control, little is yet known about how the learning-related dynamics of striatal activity are affected by dopamine depletion, a condition faced in Parkinson's disease. We made localized intrastriatal 6-hydroxydopamine lesions in rats and recorded within the dopamine-depleted sensorimotor striatal zone and its contralateral correspondent as the animals learned a conditional maze task. Rather than producing global, nonspecific elevations in firing rate across the task, the dopamine depletion altered striatal projection neuron activity and fast-spiking interneuron activity selectively, with sharply task-specific and cell type-specific effects, and often, with learning-stage selective effects as well. Striatal projection neurons with strong responses during the maze runs had especially elevated responsiveness during the maze runs. Projection neurons that, instead, fired most strongly before maze running showed elevated pre-start firing rates, but not during maze running, as learning progressed. The intrastriatal dopamine depletion severely affected the learning-related patterning of fast-spiking interneuron ensembles, especially during maze running and after extended training. Remarkably, L-DOPA treatment almost entirely reversed the depletion-induced elevations in pre-run firing of the projection neurons, and elevated their responses around start and end of maze runs. By contrast, L-DOPA failed to normalize fast-spiking interneuron activity. Thus the effects of striatal dopamine depletion and restoration on striatal activity are highly dependent not only on cell type, as previously shown, but also on the behavioral activity called for and the state of behavioral learning achieved.

Ingestion of Mycobacterium vaccae decreases anxiety-related behavior and improves learning in mice

Coevolution of microbes and their hosts has resulted in the formation of symbiotic relationships that enable animals to adapt to their environments and protect themselves against pathogens. Recent studies show that contact with tolerogenic microbes is important for the proper functioning of immunoregulatory circuits affecting behavior, emotionality and health. Few studies have examined the potential influence of ambient bacteria, such as Mycobacterium vaccae on the gut–brain–microbiota axis. In this preliminary research, we show that mice fed live M. vaccae prior to and during a maze learning task demonstrated a reduction in anxiety-related behaviors and maze completion time, when tested at three maze difficulty levels over 12 trials for four weeks. Treated mice given M. vaccae in their reward completed the maze twice as fast as controls, and with reduced anxiety-related behaviors. In a consecutive set of 12 maze trials without M. vaccae exposure, treated mice continued to run the maze faster for the first three trials, and with fewer errors overall, suggesting a treatment persistence of about one week. Following a three-week hiatus, a final maze run revealed no differences between the experimentals and controls. Additionally, M. vaccae-treated mice showed more exploratory head-dip behavior in a zero maze, and M. vaccae treatment did not appear to affect overall activity levels as measured by activity wheel usage. Collectively, our results suggest a beneficial effect of naturally delivered, live M. vaccae on anxiety-related behaviors and maze performance, supporting a positive role for ambient microbes in the immunomodulation of animal behavior.

Selective Reduction of AMPA Currents onto Hippocampal Interneurons Impairs Network Oscillatory Activity

Reduction of excitatory currents onto GABAergic interneurons in the forebrain results in impaired spatial working memory and altered oscillatory network patterns in the hippocampus. Whether this phenotype is caused by an alteration in hippocampal interneurons is not known because most studies employed genetic manipulations affecting several brain regions. Here we performed viral injections in genetically modified mice to ablate the GluA4 subunit of the AMPA receptor in the hippocampus (GluA4HC−/− mice), thereby selectively reducing AMPA receptor-mediated currents onto a subgroup of hippocampal interneurons expressing GluA4. This regionally selective manipulation led to a strong spatial working memory deficit while leaving reference memory unaffected. Ripples (125–250 Hz) in the CA1 region of GluA4HC−/− mice had larger amplitude, slower frequency and reduced rate of occurrence. These changes were associated with an increased firing rate of pyramidal cells during ripples. The spatial selectivity of hippocampal pyramidal cells was comparable to that of controls in many respects when assessed during open field exploration and zigzag maze running. However, GluA4 ablation caused altered modulation of firing rate by theta oscillations in both interneurons and pyramidal cells. Moreover, the correlation between the theta firing phase of pyramidal cells and position was weaker in GluA4HC−/− mice. These results establish the involvement of AMPA receptor-mediated currents onto hippocampal interneurons for ripples and theta oscillations, and highlight potential cellular and network alterations that could account for the altered working memory performance.

Theta and gamma coherence across the septotemporal axis during distinct behavioral states

Theta (4-12 Hz) and gamma (40-100 Hz) field potentials represent the interaction of synchronized synaptic input onto distinct neuronal populations within the hippocampal formation. Theta is quite prominent during exploratory activity, locomotion, and REM sleep. Although it is generally acknowledged that theta is coherent throughout most of the hippocampus, there is significant variability in theta, as well as gamma, coherence across lamina at any particular septotemporal level of the hippocampus. Larger differences in theta coherence are observed across the septotemporal (long) axis. We have reported that during REM sleep there is a decrease in theta coherence across the long axis that varies with the topography of CA3/mossy cell input rather than the topography of the prominent entorhinal input. On the basis of differences in the rat's behavior as well as the activity of neuromodulatory inputs (e.g., noradrenergic and serotonergic), we hypothesized that theta coherence across the long axis would be greater during locomotion than REM sleep and exhibit a pattern more consistent with the topography of entorhinal inputs. We examined theta and gamma coherence indices at different septotemporal and laminar sites during distinct theta states: locomotion during maze running, REM sleep, following acute treatment with a θ-inducing cholinomimetic (physostigmine) and for comparison during slow-wave sleep. The results demonstrate a generally consistent pattern of theta and gamma coherence across the septotemporal axis of the hippocampus that is quite indifferent to sensory input and overt behavior. These results are discussed with regards to the neurobiological mechanisms that generate theta and gamma and the growing body of evidence linking theta and gamma indices to memory and other cognitive functions.

The uncompetitive N-methyl- d-aspartate (NMDA) receptor antagonist memantine prolongs spatial memory in a rat delayed radial-arm maze memory task

In the present study, we evaluated the effects of memantine in a delayed radial-arm maze rat task, consisting of an acquisition phase followed 18 h later by a win-shift retrieval test. When administered 20 min before acquisition, memantine elicited an inverted U-shape dose–response relationship, with low doses (0.3 and 0.56 mg/kg) reducing the number of errors committed during the retrieval test, while high doses (3 and 10 mg/kg) disrupted maze running. Memantine given immediately after acquisition or 20 min before retrieval failed to affect performance. Co-administration of subthreshold doses of memantine with either the CB 1 receptor antagonist rimonabant or the acetylcholine esterase inhibitor donepezil failed to enhance performance. Thus, low doses of memantine enhance acquisition processes that lead to prolonged spatial memory.

The Mozart Effect in Rats: Response to Steele

Steele (2003) raised several concerns regarding Rauscher, Robinson, and Jens’ (1998) study that found improved maze running following early music exposure in rats. Steele’s primary criticisms were that the rats in the Rauscher et al. study were only able to hear 31% of the notes and that a selection bias resulting in preexisting differences between groups could account for the disparity in their performance. Here we provide evidence that the rats heard a substantially higher percentage of notes than Steele reported and that there were no preexisting differences between groups. A recent replication is discussed that shows a neurophysiological basis for a Mozart effect in rats.

An automated olfactory discrimination procedure with rats.

Although rats are commonly used as subjects in psychological research, few researchers have utilized their olfactory capabilities. An automated chamber capable of presenting multiple odor stimuli to 5 locations was used to train rats on 3 simple dis crimination and reversal tasks. Unique odor pairs were used for each and reversal task (Sets A, B, & C). All rats readily learned each task, taking longer to learn the reversal than the initial discrimination. Stimulus location did not influence accuracy, with only two exceptions. Moreover, rats showed no position biases for any of the 5 locations. These data demonstrate the feasibility of testing rats using olfactory cues in an automated apparatus with as many as 5 stimulus locations. This apparatus and procedure have potential applications to many areas of psychological investigation, including extra-dimensional shifts, compound stimulus training, and conditional discriminations. Key words: olfactory, stimulus location, nose poke, rats ********** Rats are commonly used subjects in psychological research that are frequently tested on tasks that require bar pressing or maze running. Moreover, these tasks are typically used to examine associative, or learning in rats. Few researchers, however, have supplanted these methodologies reliant on pressing and running behavior with those that take advantage of rats' superior sense of smell. For example, a search of the abstracts on PsychINFO returned over 23,000 references using the keyword discrimination, but only 627 when the keywords rat and discrimination were combined. Utilizing odor cues in tests involving rats is advantageous because this species possesses a biological preparedness for learning about odors. For example, Nigrosh, Slotnick, and Nevin (1975) demonstrated that when responding was brought under control of redundant odor and tone cues, control of behavior was more effective with the odor cue (but see Neill & Harrison, 1987, for a discussion on the variables influencing auditory learning in rats). Moreover, developing reliable behavioral tests that take advantage of rodents' olfactory sense has the potential to increase the utility of animal models of conditions, such as mental retardation, that are partially defined in terms of their behavioral effects (e.g, McIlvane & Cataldo, 1996). Nonetheless, the absence of utilizing olfactory stimuli in studies of learning remains notable. One possible reason is the inherent difficulty of working with them. Despite this, some researchers have attempted the challenge. Bunsey and Eichenbaum (1996) trained rats on matching to sample conditional discriminations using olfactory stimuli. Everyday household spices were mixed into sand and placed in small cups. Rats were required to dig into the cups to obtain reinforcement (a piece of chocolate). This procedure was effective in establishing reliable matching behavior. Moreover, the basic procedure has been replicated (Dudchenko, Wood, & Eichenbaum, 2000; Wood, Dudchenko, & Eichenbaum, 1999) and has been successfully modified for simple training with both rats and mice (Dusek & Eichenbaum, 1997; Mihalick, Langlois, Krienke, & Dube, 2000, respectively). Despite the success of this procedure, there are some disadvantages: a large number of scented cups need to be mixed prior to each session, the researchers have to manually present each stimulus during the session, and data have to be recorded by hand. Pena, Pitts and Galizio (2006) have taken this innovative idea further by conducting sessions in a standard operant chamber and streamlining the sand-cup delivery process. Baited sand cups are presented to the rats by sliding a tray that fits underneath the floor in and out of the chamber. This procedure involves less contact with the subjects during the session but still requires manual data recording. …

Differential behavioral state-dependence in the burst properties of CA3 and CA1 neurons

Brief bursts of fast high-frequency action potentials are a signature characteristic of CA3 and CA1 pyramidal neurons. Understanding the factors determining burst and single spiking is potentially significant for sensory representation, synaptic plasticity and epileptogenesis. A variety of models suggest distinct functional roles for burst discharge, and for specific characteristics of the burst in neural coding. However, little in vivo data demonstrate how often and under what conditions CA3 and CA1 actually exhibit burst and single spike discharges.The present study examined burst discharge and single spiking of CA3 and CA1 neurons across distinct behavioral states (awake-immobility and maze-running) in rats. In both CA3 and CA1 spike bursts accounted for less than 20% of all spike events. CA3 neurons exhibited more spikes per burst, greater spike frequency, larger amplitude spikes and more spike amplitude attenuation than CA1 neurons.A major finding of the present study is that the propensity of CA1 neurons to burst was affected by behavioral state, while the propensity of CA3 to burst was not. CA1 neurons exhibited fewer bursts during maze running compared with awake-immobility. In contrast, there were no differences in burst discharge of CA3 neurons. Neurons in both subregions exhibited smaller spike amplitude, fewer spikes per burst, longer inter-spike intervals and greater spike amplitude attenuation within a burst during awake-immobility compared with maze running. These findings demonstrate that the CA1 network is under greater behavioral state-dependent regulation than CA3. The present findings should inform both theoretic and computational models of CA3 and CA1 function.

Nucleus accumbens dopamine and rate of responding: Neurochemical and behavioral studies

It has been suggested that accumbens dopamine (DA) is involved in the process of enabling organisms to expend energy in various situations, including foraging, maze running, and leverpressing. Although accumbens DA depletions impair stimulant self-administration, the effects of these depletions on various food-reinforced operant schedules are highly variable. Accumbens DA depletions have little or no effect on total response output in rats responding on the simplest schedule of food reinforcement (i.e., the fixed ratio 1). In addition, it has been shown clearly that the effects of accumbens DA depletions do not resemble the effects of extinction or prefeeding to reduce food motivation. Over the last several years, our laboratory has investigated the effects of accumbens DA depletions on several schedules, including fixed ratio 1, variable interval 30 sec, fixed interval 30 sec, progressive ratio, and fixed ratio 4, 5, 16, and 64. These schedules generate very different rates of responding, ranging from 300 to 3,000 responses per 30 min. Regression analyses of all these studies indicates a significant linear relation between control rates of responding and the degree of suppression of responding produced by accumbens DA depletions. Schedules that generate relatively low response rates, such as fixed ratio 1 or variable interval 30 sec, are little affected by accumbens DA depletions, yet schedules that generate high response rates (e.g., fixed ratio 64) are severely disrupted. Prefeeding shows different patterns of suppression as a function of response rate. Microanalysis of the temporal characteristics of lever-pressing has shown that accumbens DA depletions produce a response slowing, as measured by the interresponse time; extinction and prefeeding produce a different pattern of effects. These results indicate that accumbens DA depletions do not blunt the reinforcing effects of food, but do suppress responding in a rate-dependent manner. In addition, microdialysis studies have shown that accumbens DA release is positively correlated with leverpressing response rate. Accumbens DA appears to be involved in energy expenditure, behavioral activation, or maintenance of high local rates of responding, which are functions that represent an area of overlap between motor and motivational processes.

Open-field Δ-ambulation as a selection tool for bidirectional responses in maze learning in Mus musculus L.

This paper presents the results of a bidirectional selective breeding experiment involving 1,287 mice. It was conducted by means of Δ-ambulation—that is, by summing positive and negative learning-associated alterations in open-field ambulation over a 5-day period of training. Δ-ambulation remained constant, but a selection response was found in maze running times and error scores over generations and sexes in the two diverging, intralinearly homogenous, strains of mice.

Neonatal enucleation induces cross-modal changes in the barrel cortex of rat. A behavioural and electrophysiological study

The present study was undertaken to determine whether neonatal enucleation leads to functional changes in the somato-sensory system and whether it has any behavioural effects. Binocular enucleation was performed on newborn rats. The effects of enucleation were tested versus controls in a rectangular maze on 10 successive days starting on postnatal day 80. Immediately after the 10-day behavioural study session, electro-physiological experiments were performed on 5 enucleated and 5 control rats. All the whiskers of the remaining animals were clipped off on both sides, and these animals continued the maze running for four additional sessions. The behavioural study demonstrated that the maze performance achieved by the neonatally enucleated animals was better than that of the controls. This suggested that cross-modal compensatory changes took place in other sensory systems, presumably somatosensory too. This was supported by the result of the experiment preceded by bilaterial vibrissa clipping. The electrophysiological experiments clearly revealed that functional changes took place in the somatosensory system of enucleated rats. In these animals, the cells in some barrels (C1 and E3) displayed enlarged receptive fields, while in an other barrel (A3) an increased angular sensitivity for deflection of its related whisker was observed. This combined study clearly demonstrates that neonatal enucleation is able to induce cross-modal compensatory changes in the somatosensory system of the rat.

Using self-organising feature maps for the control of artificial organisms

Variations on the standard Kohonen feature map can enable an ordering of the map state space by using only a limited subset of the complete input vector. Also it is possible to employ merely a local adaptation procedure to order the map, rather than having to rely on global variables and objectives. Such variations have been included as part of a hybrid learning system (HLS) which has arisen out of a genetic-based classifier system. In this paper a description of the modified feature map is given, which constitutes the HLSs long term memory, and results on the control of a simple maze running task are presented, thereby demonstrating the value of goal related feedback within the overall network.

Radial maze performance following hippocampal kindling

The relation between hippocampal epileptiform activity and 8-arm radial maze performance was assessed following repetitive afterdischarges (ADs) evoked by stimulation of the hippocampal CA1 region (kindling). Hippocampal kindling, whether to stage V (generalized) convulsions or to a preconvulsive stage, induced deficits in radial maze performance, evaluated by correct arm entries in 8 choices or total maze run (trial) time. The deficits persisted at least until 21 days after the last AD. Hippocampal interictal spikes (ISs) were induced by kindling, but the rate of ISs declined to near zero in a few days. The rate or presence of ISs was not related to maze performance.

Parallel automated wire-routing with a number of competing processors

The purpose of the automated wire routing for VLSI and printed circuit board design is to connect a number of terminal pairs distributed throughout wiring plane with net paths which do not intersect each other. Although maze running and line search are well known algorithms used for this purpose, they need a considerable computing time. To reduce it we have developed a new parallel routing algorithm in which a number of processors compete in wiring different nets independent of each other, and one master processor verifies their results and judges. The master processor also delivers an assignment message to the processors. The efficiency of this algorithm was evaluated on a binary-tree multicomputer and more than 50 times of speedup was obtained when 3000 random nets were routed by using 63 processing elements.

TRH analog MK-771 reverses neurochemical and learning deficits in medial septal-lesioned rats

Microinjection of ibotenic acid into medial septum of rats decreased choline acetyltransferase (CAT) and high-affinity choline uptake (HACU) activities in hippocampus and retarded the learning of a spatial memory task in the radial-arm maze. Administration of MK-771, a stable TRH analog, to such animals restored HACU activity in hippocampus to normal levels. Daily treatment of rats with MK-771 prior to maze running also restored the animals' learning ability. MK-771 did not enhance hippocampal HACU activity or maze performance in sham-lesioned rats. These results suggest that MK-771 reversed the ibotenic acid-induced memory deficit by restoring septohippocampal cholinergic function. MK-771 and other TRH analogs may represent novel agents for improving memory deficits produced by cholinergic insufficiency in Alzheimer's disease.

Relationship of Vibrissal Length and Habits in the Sciuridae

One of the most striking facial features of mammals is the presence of vibrissae, also known as whiskers or tactile hairs (the term preferred by Nomina Anatomica Veterinaria, 1983). In fact vibrissae (the term preferred by most authors) are found on almost all mammals except Homo sapiens; some mammals that lack vibrissae as adults develop them prenatally, only to lose them before birth (Cave, 1969). The near universality of vibrissae and the great variety and array in which they appear on the face and body of mammals suggests that they are important in the life of the mammal. Indeed there is great variation in vibrissae numbers among species whereas that within species is reported to be low (Dun and Fraser, 1959). Vibrissae are not merely pelage hairs that have attained greater length and thickness, but are specialized hairs that arise from a sinus hair follicle that is 5-6 times larger (longer and broader) than a pelage follicle. Each mystacial vibrissa (located on the upper lip in ordered rows) is represented by a separate barreloid in the brain stem nuclei and a barrel in the sensory cortex, giving a precise one-to-one mapping of the skin surface in the brain stem and the brain. No other sensory system is known to exhibit the discreteness of this vibrissa-to-barrel path (Van der Loos and Dorfl, 1978). Such exquisite anatomical precision internally demands an assumption of important function externally. In fact, the question seems to be not whether vibrissae are important in an animal's life and behavior, but how they function and what aspects of an animal's life are involved. Vibrissae have been implicated in a variety of functions in different species, including aggressive behavior and fighting (Flory et al., 1965), social dominance (Strozik and Festing, 1981), swimming (Ahl, 1982), protective eyeblink reflex (Fitzgerald, 1940; McGill, 1982; Van Horn, 1970), equilibrium and surface discrimination (Vincent, 1912), depth perception (Schiffman et al., 1970), maze running (Oliver, 1977; Vincent 1912), predatory behavior (Gregoire and Smith, 1975; Kemble and Lewis, 1982; MacDonnell and Flynn, 1966; Renouf, 1980), and others. Extensive reviews of vibrissae and neural function (Gustafson and FelbainKeramidas, 1977) and vibrissae and behavior (Ahl, 1986) are available for further information. However, showing how useful vibrissae are to their possessors is not easy to demonstrate. A direct attempt to test survival value of vibrissae for small rodents in the wild was made by dividing each of two species of mice (Reithrodontomys megalotis and Microtus californicus) into three groups: (1) no vibrissae clipped, (2) vibrissae clipped on one side, and (3) fibrissae clipped on both sides (Pearson, 1962). These mice were tagged, released, and retrapped 3-6 weeks later. Clipping the vibrissae did not affect the probability of a mouse's survival. However, Pearson was unwilling to conclude that vibrissae have no survival value: . .. it is perhaps safest to follow the course of some others who have sought in vain to gather from nature experimental confirmation of evolutionary theory, and to conclude that vibrissae have survival value ... under ... circumstances other than those prevailing in the present experiment. The possible relationship of mystacial vibrissal length and life habits in mammals has long been suggested in the literature, and includes the idea that vibrissae are more highly developed in active arboreal species than in terrestrial ones (Pocock, 1914). A small vibrissal field with vibrissae extending little beyond the width of the head, has been associated with burrowing species by Kratochvil (1968). Nocturnal species, especially arboreal ones, should have especially well-developed vibrissae as their eyes are less useful than for diurnal species, making the vibrissae important for detecting objects that are near to the face. In order to establish whether mystacial vibrissal length is related to the habit of mammals, I chose to study the Sciuridae. They are similar physiologically, and have diverged into many habitats. Because most species are diurnal, differences in vibrissal development can be related to habit and not to time of activity. Additionally, the flying squirrels are both arboreal and nocturnal, thus providing a partial test of the nocturnal hypothesis. The size of most species is in the small to medium range; this becomes an important consideration because as mammals increase in size, vibrissae cannot increase proportionally for they would soon become brush brooms that would interfere with rather than aid the animal in its activities. In fact, the only very