Hippocampal Global Remapping Can Occur without Input from the Medial Entorhinal Cortex.

The high storage capacity of the episodic memory system relies on distinct representations for events that are separated in time and space. The spatial component of these computations includes the formation of independent maps by hippocampal place cells across environments, referred to as global remapping. Such remapping is thought to emerge by the switching of input patterns from specialized spatially selective cells in medial entorhinal cortex (mEC), such as grid and border cells. Although it has been shown that acute manipulations of mEC firing patterns are sufficient for inducing hippocampal remapping, it remains unknown whether specialized spatial mEC inputs are necessary for the reorganization of hippocampal spatial representations. Here, we examined remapping in rats without mEC input to the hippocampus and found that highly distinct spatial maps emerged rapidly in every individual rat. Our data suggest that hippocampal spatial computations do not depend on inputs from specialized cell types in mEC

Parallel and convergent processing in grid cell, head-direction cell, boundary cell, and place cell networks.

The brain is able to construct internal representations that correspond to external spatial coordinates. Such brain maps of the external spatial topography may support a number of cognitive functions, including navigation and memory. The neuronal building block of brain maps are place cells, which are found throughout the hippocampus of rodents and, in a lower proportion, primates. Place cells typically fire in one or few restricted areas of space, and each area where a cell fires can range, along the dorsoventral axis of the hippocampus, from 30 cm to at least several meters. The sensory processing streams that give rise to hippocampal place cells are not fully understood, but substantial progress has been made in characterizing the entorhinal cortex, which is the gateway between neocortical areas and the hippocampus. Entorhinal neurons have diverse spatial firing characteristics, and the different entorhinal cell types converge in the hippocampus to give rise to a single, spatially modulated cell type-the place cell. We therefore suggest that parallel information processing in different classes of cells-as is typically observed at lower levels of sensory processing-continues up into higher level association cortices, including those that provide the inputs to hippocampus. WIREs Cogn Sci 2014, 5:207-219. doi: 10.1002/wcs.1272 Conflict of interest: The authors have declared no conflicts of interest for this article. For further resources related to this article, please visit the WIREs website

Chemical-Mediated Mate Attraction in Clover Root Curculio (\u3ci\u3eSitona hispidulus\u3c/i\u3e F.), A Belowground Pest of Forage Crops

Curculionid beetles are well known for their production of semiochemicals, including contact (e.g. cuticular hydrocarbons) and volatile pheromones that mediate conspecific attraction and mating. Clover root curculio (CRC; Sitona hispidulus) in particular is an emergent, soil-borne pest of significant concern to producers of alfalfa and other leguminous crops in the United States. Producers have few control options for CRC and a greater understanding of chemical-mediated attraction in this species can potentially improve the sustainability of its management. To examine which chemical cues are important for affecting the behavior of CRC and whether there are sex-based differences in response, I performed behavioral assays using an olfactometer (i.e., Y-tube). This effort was complemented with solvent-based extractions of cuticular hydrocarbons and analysis via Gas Chromatograph Mass Spectrometer (GC-MS) to characterize contact chemicals that can also contribute to conspecific recognition and attraction. Olfactometer assays suggest that CRC most likely has a male-produced, volatile aggregation pheromone, as females exhibited a strong preference for male odors. In contrast, our cuticular hydrocarbon data suggest a lack of sex differences in their epicuticular wax layer. Knowledge of chemicals involved in mediation of Curculionidae mating interactions is essential for the development of ecologically sound strategies for the control of below-ground pests. Once semiochemicals are identified and behaviors observed, we can use this knowledge to develop a cost-effective detection method, such as semiochemical-baited traps. These traps could alert growers of the presence of CRC in their fields, disrupt mating, as well as draw some away from their crops

The medial entorhinal cortex is necessary for temporal organization of hippocampal neuronal activity.

The superficial layers of the medial entorhinal cortex (MEC) are a major input to the hippocampus. The high proportion of spatially modulated cells, including grid cells and border cells, in these layers suggests that MEC inputs are critical for the representation of space in the hippocampus. However, selective manipulations of the MEC do not completely abolish hippocampal spatial firing. To determine whether other hippocampal firing characteristics depend more critically on MEC inputs, we recorded from hippocampal CA1 cells in rats with MEC lesions. Theta phase precession was substantially disrupted, even during periods of stable spatial firing. Our findings indicate that MEC inputs to the hippocampus are required for the temporal organization of hippocampal firing patterns and suggest that cognitive functions that depend on precise neuronal sequences in the hippocampal theta cycle are particularly dependent on the MEC

The Effects of Montessori’s “Walking on the Line” Activity on Student Engagement and Concentration

This paper investigates whether and to what degree Montessori’s “Walking on the Line” activity affected student engagement and concentration. This study took place in a private Montessori classroom serving twenty students, aged 33 months through five years. Data was collected using four tools on line usage, engagement, and concentration: a tally of how many times students walked the line, a tally measuring how engaged students appeared while working in the classroom, how long students concentrated following a lesson, and a professional journal. All but the line usage tool gathered baseline data five days before the intervention. Results were inconclusive. While overall student engagement and concentration rose, there was little to no correlation between number of times students walked on the line daily and engagement or concentration. I will continue to offer this activity while investigating additional activities to increase engagement and concentration

Neuronal activity regulates neurotransmitter switching in the adult brain following light-induced stress.

Neurotransmitter switching in the adult mammalian brain occurs following photoperiod-induced stress, but the mechanism of regulation is unknown. Here, we demonstrate that elevated activity of dopaminergic neurons in the paraventricular nucleus of the hypothalamus (PaVN) in the adult rat is required for the loss of dopamine expression after long-day photoperiod exposure. The transmitter switch occurs exclusively in PaVN dopaminergic neurons that coexpress vesicular glutamate transporter 2 (VGLUT2), is accompanied by a loss of dopamine type 2 receptors (D2Rs) on corticotrophin-releasing factor (CRF) neurons, and can lead to increased release of CRF. Suppressing activity of all PaVN glutamatergic neurons decreases the number of inhibitory PaVN dopaminergic neurons, indicating homeostatic regulation of transmitter expression in the PaVN