Modeling hippocampal spatial cells in rodents navigating in 3D environments.

Studies on the neural correlates of navigation in 3D environments are plagued by several issues that need to be solved. For example, experimental studies show markedly different place cell responses in rats and bats, both navigating in 3D environments. In this study, we focus on modelling the spatial cells in rodents in a 3D environment. We propose a deep autoencoder network to model the place and grid cells in a simulated agent navigating in a 3D environment. The input layer to the autoencoder network model is the HD layer, which encodes the agent's HD in terms of azimuth (θ) and pitch angles (ϕ). The output of this layer is given as input to the Path Integration (PI) layer, which computes displacement in all the preferred directions. The bottleneck layer of the autoencoder model encodes the spatial cell-like responses. Both grid cell and place cell-like responses are observed. The proposed model is verified using two experimental studies with two 3D environments. This model paves the way for a holistic approach using deep neural networks to model spatial cells in 3D navigation.

An integrated deep learning-based model of spatial cells that combines self-motion with sensory information.

A special class of neurons in the hippocampal formation broadly known as the spatial cells, whose subcategories include place cells, grid cells, and head direction cells, are considered to be the building blocks of the brain's map of the spatial world. We present a general, deep learning-based modeling framework that describes the emergence of the spatial-cell responses and can also explain responses that involve a combination of path integration and vision. The first layer of the model consists of head direction (HD) cells that code for the preferred direction of the agent. The second layer is the path integration (PI) layer with oscillatory neurons: displacement of the agent in a given direction modulates the frequency of these oscillators. Principal component analysis (PCA) of the PI-cell responses showed the emergence of cells with grid-like spatial periodicity. We show that the Bessel functions could describe the response of these cells. The output of the PI layer is used to train a stack of autoencoders. Neurons of both the layers exhibit responses resembling grid cells and place cells. The paper concludes by suggesting the wider applicability of the proposed modeling framework beyond the two simulated studies.

Women's decision-making and contraceptive use in Pakistan: an analysis of Demographic and Health Survey data.

This study examines the association of decision-making with contraceptive use along with other measures of women's empowerment and the gender context. We use data on currently married women from the Demographic and Health Survey conducted in Pakistan in 2017-2018. We contrast patterns in modern contraception with traditional contraception and examine specific modern methods. Husband's characteristics do not factor strongly in women's modern contraceptive use. Contraceptive decision-making is more pertinent to women's modern contraceptive use than household decision-making and is inhibited when husbands are the primary decision-makers of contraceptive decisions. In contrast, joint decision-making facilitates overall modern contraceptive use and the use of condoms in particular. Contraceptive use is reduced when the decision is made by someone other than the woman or her husband. Economic empowerment resources are weakly and inconsistently associated with modern contraceptive use. Furthermore, modern contraceptive use (particularly condoms and female sterilisation) is reduced when women live in an extended household. Region, education, and wealth remain important correlates of modern contraceptive use, even after controlling for other factors, as does the number of living children and, for female sterilisation and IUDs only, women's working status. This study finds support for expanding the range of available methods and combining service improvements with promoting women's empowerment, gender equity, and social behaviour change initiatives targeted to men and other family members.