Reduced delayed-rectifier K+ current in the learning mutant rutabaga

In the Drosophila mutant rutabaga, short-term memory is deficient and intracellular cyclic adenosine monophosphate (cAMP) concentration is reduced. We characterized the delayed-rectifier potassium current (IK_DR) in rutabaga as compared with the wild-type. The conventional whole-cell patch-clamp technique was applied to cultured Drosophila neurons derived from embryonic neuroblasts. IK_DR was smaller in rutabaga (368±11 pA) than in wild-type (541±14 pA) neurons, measured in a Ca²⁺-free solution. IK_DR was clearly activated at ~0 mV in the two genotypes. IK_DR typically reached its peak within 10–20 msec after the start of the pulse (60 mV). There was no difference in inactivation of IK_DR for wild-type (14±3%) and rutabaga (19±3%). After application of 10 mM TEA, in wild-type, IK_DR was reduced by 46±5%, whereas in rutabaga, IK_DR was reduced by 28±3%. Our results suggest that IK_DR is carried by two different types of channels, one which is TEA-sensitive, whereas the other is TEA-insensitive. Apparently, the TEA-sensitive channel is less expressed in rutabaga neurons than in wild-type neurons. Conceivably, altered neuronal excitability in the rutabaga mutant could disrupt the processing of neural signals necessary for learning and memory.     

Chronic, severe hypertension does not impair spatial learning and memory in Sprague-Dawley rats

This study tested the hypothesis that long-term hypertension impairs spatial learning and memory in rats. In 6-wk-old Sprague-Dawley rats, chronic hypertension was induced by placing one of three sizes of stainless steel clips around the descending aorta (above the renal artery), resulting in a 20–80-mm Hg increase of arterial pressure in all arteries above the clip, that is, the upper trunk and head. Ten months later, the rats were tested for 5 d in a repeated-acquisition water maze task, and on the fifth day, they were tested in a probe trial; that is, there was no escape platform present. At the end of the testing period, the nonsurgical and sham control groups had similar final escape latencies (16±4 sec and 23±9 sec, respectively) that were not significantly different from those of the three hypertensive groups. Rats with mild hypertension (140–160 mm Hg) had a final escape latency of 25±6 sec, whereas severely hypertensive rats (170–199 mm Hg) had a final escape latency of 21±7 sec and extremely hypertensive rats (>200 Hg) had a final escape latency of 19±5 sec. All five groups also displayed a similar preference for the correct quadrant in the probe trial. Together, these data suggest that sustained, severe hypertension for over 10 mo is not sufficient to impair spatial learning and memory deficits in otherwise normal rats.     

Expression of Fos and Jun Proteins Following Passive Avoidance Training in the Day-Old Chick

It has been shown previously that the immediate-early genes, c-fos and c-jun mRNA are induced in the 1-day-old chick forebrain after one-trial passive avoidance training in which chicks learn to avoid pecking at a bitter-tasting bead. Here, we have studied the expression of their proteins using antibodies to Fos and Jun. Western blotting disclosed two immunoreactive bands for the anti-Fos antibody (47 and 54 kD) and two immunoreactive bands for the anti-Jun antibody (39 and 54 kD). Two hours post-training there was an increase in the number of Fos-positive stained nuclei in right intermediate medial hyperstriatum ventrale (IMHV) (P<0.01), left IMHV (P<0.05), right lobus parolfactorius (LPO) (P<0.025) and left LPO (P<0.05) of birds trained on the bitter bead compared with controls that had pecked a water-coated bead. Staining for Jun protein was significantly greater in the right LPO of trained chicks (P<0.01). Other forebrain regions showed no increase over quiet control levels. The findings are discussed in the context of the cascade of events involved in passive avoidance memory consolidation in the day-old chick.     

Emotional memory formation is enhanced across sleep intervals with high amounts of rapid eye movement sleep

Recent studies indicated a selective activation during rapid eye movement (REM) sleep of the amygdala known to play a decisive role in the processing of emotional stimuli. This study compared memory retention of emotional versus neutral text material over intervals covering either early sleep known to be dominated by nonREM slow wave sleep (SWS) or late sleep, in which REM sleep is dominant. Two groups of men were tested across 3-h periods of early and late sleep (sleep group) or corresponding retention intervals filled with wakefulness (wake group). Sleep was recorded polysomnographically. Cortisol concentrations in saliva were monitored at acquisition and retrieval testing. As expected, the amount of REM sleep was about three times greater during late than during early retention sleep, whereas a reversed pattern was observed for SWS distribution (P<0.001). Sleep improved retention, compared with the effects of wake intervals (P<0.02). However, this effect was substantial only in the late night (P<0.005), during which retention was generally worse than during the early night (P<0.02). Late sleep particularly enhanced memory for emotional texts. This effect was highly significant in comparison with memory for neutral texts (P<0.01) and in comparison with memory after late and early wake intervals (P<0.001). Cortisol concentration differed between early and late retention intervals but not between sleep and wake conditions. Results are consonant with a supportive function of REM sleep predominating late sleep for the formation of emotional memory in humans.     

Two Modulatory Inputs Exert Reciprocal Reinforcing Effects on Synaptic Input of Premotor Interneurons for Withdrawal in Terrestrial Snails

A cluster of serotonergic cells in the rostral part of pedal ganglia of the terrestrial snail Helix lucorum was shown previously to participate in modulation of withdrawal behavior, and to be necessary for elaboration of aversive withdrawal conditioning in intact snails. In the present experiments local extracellular stimulation of the serotonergic cells elicited a pairing-specific increase (difference between paired and explicitly unpaired sessions was significant, P<0.01) of synaptic responses in the premotor interneurons involved in withdrawal to paired nerve stimulation. Intracellular stimulation of only one Pd4 cell from the pedal group of serotonergic neurons increased (P<0.05) synaptic responses to contingent test nerve stimulation significantly in the same premotor interneurons for 2–3 hr.     

Automated Measurement of Mouse Freezing Behavior and its Use for Quantitative Trait Locus Analysis of Contextual Fear Conditioning in (BALB/cJ × C57BL/6J)F2 Mice

The most commonly measured mouse behavior in fear conditioning tests is freezing. A technical limitation, particularly for genetic studies, is the method of direct observation used for quantifying this response, with the potential for bias or inconsistencies. We report the use of a computerized method based on latency between photobeam interruption measures as a reliable scoring criterion in mice. The different computer measures obtained during contextual fear conditioning tests showed high correlations with hand-scored freezing; r values ranged from 0.87 to 0.94. Previously reported strain differences between C57BL/6J and DBA/2J in context-dependent fear conditioning were also detected by the computer-based system. In addition, the use of computer-scored freezing of 199 (BALB/cJ×C57BL/6J)F₂ mice enabled us to detect a suggestive gender-dependent chromosomal locus for contextual fear conditioning on distal chromosome 8 by QTL analysis. Automation of freeze scoring would significantly increase efficiency and reliability of this learning and memory test.     

Hippocampal Activations during Repetitive Learning and Recall of Geometric Patterns

Hippocampal activation is required for episodic memory. Encoding and retrieval of novel and memorable items have been related to different locations in the hippocampus; however, the data remain ambiguous. The application of a newly designed keyboard allowed investigation of brain activation during encoding and free immediate and delayed recall with functional magnetic resonance imaging (fMRI) in young healthy controls (n=12). Because of the repetitive learning and recall conditions, an individual learning gradient was used to contrast neural activity at different individual levels of novelty. During learning, subjects were asked to memorize 10 geometric patterns requiring the establishment of intra-item associations for memorization. After learning, subjects were asked to recall the items actively via the keyboard. Learning and recall were alternated five times. Delayed recall was scanned about 15 min after the fifth immediate recall condition without subjects having seen the items again. Left-sided anterior hippocampal activity was observed during conditions of initial learning as well as maximum recall. Neural activity during delayed recall did not reveal hippocampal responses and was characterized by a transition of neural activity from occipitoparietal regions to bilateral temporal cortices. We conclude that both lateralization and segregation depend on the specific relational characteristics of the stimuli requiring establishment of intra-item associations for encoding as well as retrieval. The absence of hippocampal activation during delayed recall together with the increase of lateral temporal involvement possibly corresponds with an emerging transition from episodic to long-term memory.     

SENSITIVITY OF CONDITIONAL-DISCRIMINATION PERFORMANCE TO WITHIN-SESSION VARIATION OF REINFORCER FREQUENCY

The present experiment developed a methodology for assessing sensitivity of conditional-discrimination performance to within-session variation of reinforcer frequency. Four pigeons responded under a multiple schedule of matching-to-sample components in which the ratio of reinforcers for correct S₁ and S₂ responses was varied across components within session. Initially, five components, each arranging a different reinforcer-frequency ratio (from 19 to 91), were presented randomly within a session. Under this condition, sensitivity to reinforcer frequency was low. Sensitivity failed to improve after extended exposure to this condition, and under a condition in which only three reinforcer-frequency ratios were varied within session. In a later condition, three reinforcer-frequency ratios were varied within session, but the reinforcer-frequency ratio in effect was differentially signaled within each component. Under this condition, values of sensitivity were similar to those traditionally obtained when reinforcer-frequency ratios for correct responses are varied across conditions. The effects of signaled vs. unsignaled reinforcer-frequency ratios were replicated in two subsequent conditions. The present procedure could provide a practical alternative to parametric variation of reinforcer frequency across conditions and may be useful in characterizing the effects of a variety of manipulations on steady-state sensitivity to reinforcer frequency.     

Effects of a delay-reinforcement procedure on performance under IRT>t schedules

Water-deprived rats were studied under a compound schedule that prescribed that responses terminating interresponse times (IRTs) greater than a fixed value t₁ (IRT > t₁ component schedule) initiated a delay of reinforcement interval t₂, at the end of which water was presented if the subject did not respond ( > t₂ component schedule). If the subject responded before the t₂ interval elapsed, the IRT > t₁ component schedule was re-initiated and water was not presented. The IRT > t₁ and > t₂ component schedules were not differentially correlated with distinctive stimuli. Rate of responding during the IRT > t₁ component decreased as a function of the value of t₂. The magnitude of the decreases in response rate appeared to be proportional to the subject's rate under the IRT > t schedule with no delay of reinforcement (t₂ = 0 sec). The effects were independent of the parameter value of the IRT > t₁ component schedule and of the rate of reinforcement. The results suggested that “efficiency” of performance under IRT > t schedules can be increased by appropriately arranging brief delays of reinforcement.     

Empirical bayes estimates of domain scores under binomial and hypergeometric distributions for test scores

We introduce two simple empirical approximate Bayes estimators (EABEs)— and —for estimating domain scores under binomial and hypergeometric distributions, respectively. Both EABEs (derived from corresponding marginal distributions of observed test scorex without relying on knowledge of prior domain score distributions) have been proven to hold -asymptotic optimality in Robbins' sense of convergence in mean. We found that, where and are the monotonized versions of and under Van Houwelingen's monotonization method, respectively, the convergence rate of the overall expected loss of Bayes risk in either or depends on test length, sample size, and ratio of test length to size of domain items. In terms of conditional Bayes risk, and outperform their maximum likelihood counterparts over the middle range of domain scales. In terms of mean-squared error, we also found that: (a) given a unimodal prior distribution of domain scores, performs better than both and a linear EBE of the beta-binomial model when domain item size is small or when test items reflect a high degree of heterogeneity; (b) performs as well as when prior distribution is bimodal and test items are homogeneous; and (c) the linear EBE is extremely robust when a large pool of homogeneous items plus a unimodal prior distribution exists.The authors are indebted to both anonymous reviewers, especially Reviewer 2, and the Editor for their invaluable comments and suggestions. Thanks are also due to Yuan-Chin Chang and Chin-Fu Hsiao for their help with our simulation and programming work.     

A Complete Axiom System for Polygonal Mereotopology of the Real Plane

This paper presents a calculus for mereotopological reasoning in which two-dimensional spatial regions are treated as primitive entities. A first order predicate language with a distinguished unary predicate c(x), function-symbols , · and – and constants 0 and 1 is defined. An interpretation for is provided in which polygonal open subsets of the real plane serve as elements of the domain. Under this interpretation the predicate c(x) is read as region x is connected and the function-symbols and constants are given their meaning in terms of a Boolean algebra of polygons. We give an alternative interpretation based on the real closed plane which turns out to be isomorphic to A set of axioms and a rule of inference are introduced. We prove the soundness and completeness of the calculus with respect to the given interpretation.     

Die Entwicklung der Diskussion um die formale Logik in der Sowjetunion

Ohne ZusammenfassungDie Literatur zur Logik in der Sowjetunion ist sehr bescheiden. Nebst einigen Kapiteln in grösseren Werken sind es folgende Schriften: Bochénski, I. M., Soviet Logic,SST, 1, 29–38. — Dahm, H., Renaissance der formalen Logik,Ost-Probleme, 1957,8, 254–267. — Philipov, A.,Logic and Dialectic in the Soviet Union, New York 1952, XI+89 pp. — Winkelmann, A., Die Stellung der formalen Logik im Sowjet-system,Scholastik, 1956,1, 85–89.     

The two cultures

Anhand von zwei Unterbereichen der künstlichen Intelligenz — den Expertensystemen und der wissenschaftlichen Entdeckung — wird aufzuzeigen versucht, daß die Beziehung zwischen der formalen und der intuitiven Kultur aus dem Gleichgewicht geraten ist. Dem Bereich der Intuition sollte größere Aufmerksamkeit gewidmet werden.

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This article is based on a presentation given on a symposium The Art of Science, in Amsterdam, Amolf, 27 May 1987. It was organized to celebrate the 65th birthday of Prof. J. o.     

Tarski hierarchies

The general notions of object- and metalanguage are discussed and as a special case of this relation an arbitrary first order language with an infinite model is expanded by a predicate symbol T₀ which is interpreted as truth predicate for . Then the expanded language is again augmented by a new truth predicate T₁ for the whole language plus T₀. This process is iterated into the transfinite to obtain the Tarskian hierarchy of languages. It is shown that there are natural points for stopping this process. The sets which become definable in suitable hierarchies are investigated, so that the relevance of the Tarskian hierarchy to some subjects of philosophy of mathematics are clarified.It should be noticed that these terms object language and meta language have only a relative sense. If, for instance, we become interested in the notion of truth applying to sentences, not of our original object-language, but of our meta-language, the latter becomes automatically the object-language of our discussion; and in order to define truth for this language, we have to go to a new meta-language — so to speak, to a meta-language of a higher level. In this way we arrive at a whole hierarchy of languages.(Tarski, 1986, p. 674f)     

An optimal property of least squares weights in prediction models

In predicting scores fromp > 1 observed scores in a sample of sizeñ, the optimal strategy (minimum expected loss), under certain assumptions, is shown to be based upon the least squares regression weights computed from a previous sample. Letting represent the correlation between and the predicted values , and letting represent the correlation between and a different set of predicted values , where w is any weighting system which is not a function of , it is shown that the probability of being less than cannot exceed .50. The relationship of this result to previous research and practical implications are discussed.     

Decomposability of the Finitely Generated Free Hoop Residuation Algebra

In this paper we prove that, for n > 1, the n-generated free algebra in any locally finite subvariety of HoRA can be written in a unique nontrivial way as Ł₂ × A′, where A′ is a directly indecomposable algebra in . More precisely, we prove that the unique nontrivial pair of factor congruences of is given by the filters and , where the element is recursively defined from the term introduced by W. H. Cornish. As an additional result we obtain a characterization of minimal irreducible filters of in terms of its coatoms. Presented by Daniele Mundici     

African American Dance - Philosophy,Aesthetics, and ‘Beauty’

This essay considers the recuperation of beauty as a productive critical strategy in discussions of African American dance. I argue that black performance in general, and African American concert dance in particular, seeks to create aesthetic sites that allow black Americans to participate in discourses of recognition and appreciation to include concepts of beauty. In this, I suggest that beauty may indeed produce social change for its attendant audiences. I also propose that interrogating the notion of beauty may allow for social change among audiences that include dance theorists and philosophers. Through a case-study consideration of work by three African American choreographers, Donald Byrd (b. 1949), Ulysses Dove (1947 – 1996), and Abdel Salaam (b. 1949), I ultimately hope to suggest critical possibilities aligning dance performance with particular aesthetic theory relevant to its documentation and interpretation.     

Is the mind-body interface microscopic?

This paper puts forward the hypothesis that consciousness might be linked to matter in a way which is more sophisticated than the traditional macroscopic Cartesian hypothesis suggests.Advances in the biophysics of the nervous system, not only on the level of its macroscopic functioning but also on the level of individual ion channels, have made the question of how finely consciousness is tied to matter and its dynamics more important. Quantum mechanics limits the attainable resolution and puts into doubt the idea of an infinitely fine-woven attachment. A recent approach to physics rekindles such a rationalist hope. Endophysics focuses on the global implications of microscopic computer simulations of chemical and biophysical processes. A complete artificial universe can be set up in the computer. It produces non-classical and nonlocal effects inside — on the interface that exists between an internal observer (fluid neuron) and the rest of the world. This interface is finer than any brain property to which the status of the mind-body interface has been attributed hitherto. A new class of experiments becomes possible in the artificial world and, by analogy, in the real world. Magnetic resonance imaging experiments, routinely performed under open-loop conditions, can be repeated under psychophysical (closed-loop) conditions — in search for microscopically induced changes in the perceived and measured structure of the world.     

Equivalents for a Quasivariety to be Generated by a Single Structure

We present some equivalent conditions for a quasivariety of structures to be generated by a single structure. The first such condition, called the embedding property was found by A.I. Mal′tsev in [6]. It says that if are nontrivial, then there exists such that A and B are embeddable into C. One of our equivalent conditions states that the set of quasi-identities valid in is closed under a certain Gentzen type rule which is due to J. Łoś and R. Suszko [5]. Presented by Jacek Malinowski     

Aids,myth, and ethics

The present paper is a commentary on an article by Larry Churchill [1]. Churchill has argued that the negative attitudes and adverse behavior we commonly encounter in connection with (suspected) AIDS patients may be understood in terms of a dualistic myth inspiring a ritual avoidance of dirt, of dirt as something that does not belong to a clean world order. The deep-seated mythical character of attitudes and behavior here makes them less accessible to the kind of rational argument commonly employed in ethics. Churchill also proposes a remedy for the (morally outrageous) dualistic mythical-ritual behavior he has focused — a remedy that may be overly intellectualistic.Three further comments are made: on the metaphorical meaning of myth, on a reductionist tendency in Churchill's deep-looking project, and on an ethically crucial ambiguity in the meaning of the other person's otherness. These (mildly critical) comments do not, however, detract from a positive overall evaluation of Churchill's basic idea that we will understand more about adverse attitudes and behavior in connection with AIDS if we think in terms of myth, ritual, dirt, and cleanliness.