Model testing, prediction and experimental protocols in neuroscience: A case study

In their theoretical and experimental reflections on the capacities and behaviours of living systems, neuroscientists often formulate generalizations about the behaviour of neural circuits. These generalizations are highly idealized, as they omit reference to the myriads of conditions that could perturb the behaviour of the modelled system in real-world settings. This article analyses an experimental investigation of the behaviour of place cells in the rat hippocampus, in which highly idealized generalizations were tested by comparing predictions flowing from them with real-world experimental results. The aim of the article is to identify (1) under what conditions even single prediction failures regarding the behaviour of single cells sufficed to reject highly idealized generalizations, and (2) under what conditions prima facie counter-examples were deemed to be irrelevant to the testing of highly idealized generalizations. The results of this analysis may contribute to understanding how idealized models are tested experimentally in neuroscience and used to make reliable predictions concerning living systems in real-world settings.     

Brain mechanisms of imagination in solving creative verbal tasks

The brain’s mechanisms of imagination were studied using electroencephalography (EEG) spectral analysis in student actors and student non-actors under three experimental conditions: when they generated coherent stories on the basis of art reproductions (STORY task); listed the details of art reproductions presented (DETAIL task); and performed simple arithmetic calculations while observing a neutral background (COUNT task). Statistical analysis showed that, in α₁ (7.5–10 Hz) and α₂ (10–12.5 Hz) frequency bands, in both groups, execution of the STORY task, in contrast to the DETAIL task, was accompanied by significantly higher spectral power (synchronization) in most of the cortical areas studied; while, the contrasts STORY-COUNT and DETAILS-COUNT, were associated with a decrease in the EEG’s power (desynchronization) in all of the areas studied. Topographic mapping of the EEG’s power showed that, in both groups, maximal differences between the STORY and DETAILS tasks were related to the central parietal area. Maximal differences between the STORY and COUNT tasks, as well as those between the DETAILS and COUNT tasks, were related mainly to the occipital areas. Based on these findings, we consider parietal areas to be stable elements of integrated brain mechanisms underlying verbal creativity in actors and nonactors. Comparing our data with previous studies, we suggest that the parietal areas are involved in the selective inhibition of visual information processing during the involvement of brain structures in the processes of imagination.     

The impact of experimental instruction on changes in EEG power during verbal creative thinking in men and women

Features of EEG pattern during verbal creative thinking depending on experimental instruction were studied in men and women. Spectral power density was analyzed in six frequency bands (4-30 Hz). Performance of a creative task produced an increase in the power of theta (4-6 Hz) and beta2 (20-40 Hz) components and decrease in the power of alpha (8-13 Hz) and betal (13-20 Hz). Changes in the alpha and betal bands were observed, predominantly, in the posterior areas, whereas power of the thetal and beta2 bands increased in the anterior areas. Independently of instruction, women demonstrated greater synchronization in the theta1 band than men, whereas in men the desynchronization in the alpha2 band (10-13 Hz) was more pronounced. When the subjects were instructed to create original sentences, a widespread decrease in the EEG power was observed in the band of 8-30 Hz as compared to instruction "to create sentences". Thus, the instruction-related changes in EEG power were not gender-specific. They may reflect neural activity mediating selective attention.     

The influence of reward on the performance of verbal creative tasks: Behavioral and EEG effects

The goal of this study was to compare the effects of the verbal instruction (IN1) that stimulated originality and of monetary reward (IN2) on the efficiency of performing a verbal creative task. The EEG patterns were also compared on the basis of mapping the bioelectric potential power within the frequency range of 4 to 30 Hz. Right-handed students (10 men and 10 women) participated in the experiment. The originality of the solution improves if a monetary reward is expected. In contrast to IN1, the promise of a monetary reward caused a global increase in task-related synchronization of bioelectric potentials in the θ₂ band. Hemispheric asymmetry of the power of the θ₁, θ₂, and α₂ rhythm grows with higher values in the right hemisphere. These changes in response to IN2 were in the background EEG, which testifies that an overall increase in hemispheric asymmetry induces a preparatory state after the promise of monetary reward. Specific changes in regional brain activity were at the β₂-rhythm frequency. In all posterior derivation, except for the frontotemporal ones, the power of the β2 rhythm decreased in response to IN2 in contrast to IN1. The rewardinduced changes in EEG were characteristic of men to a greater extent. An increase in the θ₂-rhythm asymmetry and the power of the α rhythm was observed only in men in response to a monetary reward. Our results suggest that the promise of monetary reward is favorable for creative thinking and original solutions. Gender differences of changes in the power of bioelectric potentials suggest that the neurophysiological mechanisms of creativity are different in men and women.     

Sclerotome development and morphogenesis: when experimental embryology meets genetics

The vertebra develops from the ventral part of the somite, the sclerotome. Sclerotome progenitors are subject to multiple signaling molecules secreted by the adjacent tissues that control their fate. The aim of this article is to discuss the mechanisms of sclerotome induction, chondrogenesis and morphogenesis. By integrating the results from classical studies and recent molecular advances, this will illustrate how the powerful combination of experimental embryology and genetic approaches has recently illuminated the multiple steps of vertebra formation.     

Frequency-spatial organization of brain electrical activity in creative verbal thinking: role of the gender factor

Gender differences in EEG patterns associated with verbal creativity were studied by EEG mapping. The EEGs of 18 males and 21 females (right-handed university students) were recorded during a performance of Remote Associates Task (RAT) compared with the letter-fluency and simple associate's tasks. Gender differences were found in a factor structure of the indices of verbal thinking and a score of generating words was greater in women than men. No significant gender differences in originality of associations were revealed, however, gender-related differences in the EEG-patterns were found at the final and initial stages of RAT. In men, the beta2-power was increased in both hemispheres at the beginning of test. To the end of testing, the power of oscillations in the beta2 band increased only in the central part of the cortex. In women, the beta2-power was increased to a greater extent in the right than in the left hemisphere at the initial stage of task performance, whereas the final stage was characterized by a relative decrease in beta-activity in parietotemporal cortical regions and increase in the left prefrontal region. It is suggested that the verbal creative thinking in men is based mostly on "insight" strategy whereas women additionally involve the "intellectual" strategy.     

Learning from bird brains: how the study of songbird brains revolutionized neuroscience

During the past 30 years, songbirds have become a popular model for neuroscience research. The author reviews three fundamental discoveries that have revolutionized the field and changed the way we understand the structure and function of the brain.     

Changes in the EEG power in male and female subjects during visual creative thinking

Gender-related differences in EEG patterns during creative visual thinking were investigated in 10 men and 10 women. The spectral power density was analyzed in the range of 4-30 Hz. Gender differences in the hemispheric asymmetry of theta1-rhythm desynchronization were found: females demonstrated greater desynchronization in the right hemisphere than in the left hemisphere, whereas no asymmetry was revealed in males. Only in women numerous negative correlations between creativity indices and task-induced theta1 desynchronization were found.     

Cognitive neuroscience: searching for the bottleneck in the brain

People simply cannot do two things at once, as shown by research on the so-called psychological refractory period. A new neuroimaging study has now localized the response-selection bottleneck underlying the psychological refractory period to a frontoparietal network.     

A neuroscientific grasp of concepts: from control to representation

Abstraction denotes the cognitive process by means of which general concepts are formed. The dominant view of abstraction considers it not only as a complex and sophisticated cognitive activity, but also as a distinctive hallmark of mankind. The distinctiveness of abstract thought has indeed been closely related to another feature peculiar to our species: language. Following this perspective, the possibility to entertain conceptual representations is thus precluded to animals devoid of full-blown language. I challenge this view and propose that the representational dynamic of the brain is conceivable as a type of self-organization, in which action plays a crucial part. My aim will be to investigate whether, and to what extent, conceptual knowledge can be attributed to non-linguistic animal species, with particular emphasis on nonhuman primates. I therefore introduce the notion of semantic content as a type of 'relational specification'. A review of recent neurophysiological data on the neural underpinnings of action end-states in the macaque monkey brain is presented. On the basis of this evidence, I propose that conceptual representations can be conceived as the expression of a coherent internal world model. This model decomposes the 'outer' space inhabited by things in a meaningful way only to the extent that it accords to biologically constrained, embodied invariance. Finally, I discuss how the 'comparative' neuroscientific approach to abstraction proposed here may shed some light on its nature and its evolutionary origin.     

The second joint Kemali-IBRO Mediterranean school of neuroscience is the first for invertebrate neuroscience

This meeting was held at the Stazione Zoologica Anton Dohrn, Naples, Italy, from 6th–13th July 2011. It was sponsored through a collaboration between IBRO (the International Brain Research Organisation) and the Kemali Foundation. Notably, it is the first IBRO sponsored School specifically in invertebrate neuroscience. The meeting was attended by early career researchers from countries around the Mediterranean basin and highlighted the research opportunities that this field can offer to neuroscientists at the start of their careers. Students participating in the School were introduced to a range of important invertebrate model systems. The utility of these models in addressing fundamental neurobiological problems, especially those relating to human neurological disorders, was extensively discussed. In this review, two of the participating students provide a summary of this meeting with a view to encouraging support for further activity in this arena in the future. One of the aims of the Kemali foundation is to foster enduring collaborations between scientists in the Mediterranean region. Given the enthusiastic networking both during and after the meeting, there is much promise that this goal will be realised.     

Joint generalized models for multidimensional outcomes: A case study of neuroscience data from multimodalities

This paper is motivated from the analysis of neuroscience data in a study of neural and muscular mechanisms of muscle fatigue. Multidimensional outcomes of different natures were obtained simultaneously from multiple modalities, including handgrip force, electromyography (EMG), and functional magnetic resonance imaging (fMRI). We first study individual modeling of the univariate response depending on its nature. A mixed‐effects beta model and a mixed‐effects simplex model are compared for modeling the force/EMG percentages. A mixed‐effects negative‐binomial model is proposed for modeling the fMRI counts. Then, I present a joint modeling approach to model the multidimensional outcomes together, which allows us to not only estimate the covariate effects but also to evaluate the strength of association among the multiple responses from different modalities. A simulation study is conducted to quantify the possible benefits by the new approaches in finite sample situations. Finally, the analysis of the fatigue data is illustrated with the use of the proposed methods.     

Olfactory neuroscience: beyond the bulb

High-resolution tracing of projections from the olfactory bulb to its cortical targets revealed coarse topography and stereotopy in some areas but highly distributed, combinatorial connectivity in others. These results provide a basis for understanding innate and associative olfactory processing and perception.     

Science for sale: academic meets industry

As research becomes increasingly interdisciplinary and the lines between academic and industrial pursuits blur, scientists on both sides of the fence are developing outsourcing models to build innovative collaborations and open funding opportunities.     

Cognitive neuroscience: feedback for natural visual stimuli

Recurrent signals in the brain are often associated with slower sensory and cognitive processes. Such patterns of activity may also form the basis of rapid perception.