Manual Grasparatus: A nifty tool for presenting real objects in fMRI research.

One of the greatest challenges in functional magnetic resonance imaging (fMRI) research using real objects as stimuli is their timely delivery and (pseudo)randomized presentation. To this end, we designed an apparatus which solves the majority of problems that fMRI researchers may encounter during testing. The display apparatus - here: delivering objects for manual exploration and grasping (hence the "Grasparatus") - is equipped with semi-attachable stimulus belts and, therefore, allows for presentation of numerous 3D objects in a pre-ordered sequence. Although the presentation is controlled manually and synchronized with fMRI scanning events via commands delivered to the experimenter, it is very reliable in conveying targets to their destination in different configurations and numbers. The stimuli are easily accessible to study participants either for manual or simple visual interactions because the device is highly adjustable. The main advantages of using this apparatus involve: •The easiness of its setup prior to a study and simplicity of its control during experimental functional MRI runs.•The possibility to use real size, magnet-friendly objects, firmly or semi-attached, so that different interactions are possible.•Fast exchange of stimulus sets between runs.

Object Categorization in Finer Levels Relies More on Higher Spatial Frequencies and Takes Longer.

The human visual system contains a hierarchical sequence of modules that take part in visual perception at different levels of abstraction, i.e., superordinate, basic, and subordinate levels. One important question is to identify the "entry" level at which the visual representation is commenced in the process of object recognition. For a long time, it was believed that the basic level had a temporal advantage over two others. This claim has been challenged recently. Here we used a series of psychophysics experiments, based on a rapid presentation paradigm, as well as two computational models, with bandpass filtered images of five object classes to study the processing order of the categorization levels. In these experiments, we investigated the type of visual information required for categorizing objects in each level by varying the spatial frequency bands of the input image. The results of our psychophysics experiments and computational models are consistent. They indicate that the different spatial frequency information had different effects on object categorization in each level. In the absence of high frequency information, subordinate and basic level categorization are performed less accurately, while the superordinate level is performed well. This means that low frequency information is sufficient for superordinate level, but not for the basic and subordinate levels. These finer levels rely more on high frequency information, which appears to take longer to be processed, leading to longer reaction times. Finally, to avoid the ceiling effect, we evaluated the robustness of the results by adding different amounts of noise to the input images and repeating the experiments. As expected, the categorization accuracy decreased and the reaction time increased significantly, but the trends were the same. This shows that our results are not due to a ceiling effect. The compatibility between our psychophysical and computational results suggests that the temporal advantage of the superordinate (resp. basic) level to basic (resp. subordinate) level is mainly due to the computational constraints (the visual system processes higher spatial frequencies more slowly, and categorization in finer levels depends more on these higher spatial frequencies).

Figuração e figurabilidade: no início eram as sensações / Figuration and figurability: in the beginning were the sensations

O artigo aborda a relação entre a operação onírica de figuração plástica e a noção de figurabilidade na 11ª Conferência de introdução à psicanálise. Entendida como conversão dos pensamentos latentes do sonho em imagens, a operação supõe uma série de condições de possibilidade que Freud chama figurabilidade. Assim, considera-se, em primeiro lugar, o conceito de regressão e seus pressupostos metapsicológicos. Em segundo lugar, examina-se o papel das sensações e dos seus registros mnêmicos. Por último, indaga-se acerca da explicação freudiana da preeminência do visual sobre os outros tipos de sensações.

This paper examines the relationship between the dreamlike operation of plastic figuration and the notion of figurability in the 11th Conference of Introduction to Psychoanalysis. This operation, conceptualised as the conversion of the latent thoughts of dream into images, presupposes a series of conditions of possibility that Freud calls figurability. In this paper, we begin by discussing the concept of regression and its metapsychological assumptions. We then analyse the role of sensations and their memory registers. Finally, we explore the Freudian explanation of the pre-eminence of the visual over other types of sensations.