Astronomers and physicists noticed centuries ago that visual spatial resolution is higher for dark than light stimuli, but the neuronal mechanisms for this perceptual asymmetry remain unknown. Here we demonstrate that the asymmetry is caused by a neuronal nonlinearity in the early visual pathway. We show that neurons driven by darks (OFF neurons) increase their responses roughly linearly with l...

The expansion of mobile phone technology has raised concerns regarding the effect of 900-MHz electromagnetic field (EMF) exposure on the central nervous system. At present, the developing human brain is regularly exposed to mobile telephones, pre- and postnatally. Several studies have demonstrated the acute effects of EMF exposure during pre- or postnatal periods; however, the chronic effects o...

Postweaning social isolation reduces the amplitude of the daily variation of CLOCK protein in the brain and induces lower reproductive activity. Gonadotropin-inhibitory hormone (GnIH) acts as an inhibitor in the reproductive system and has been linked to stress. Social isolation has been shown to lower neuronal activity of GnIH-expressing neurons in the dorsomedial hypothalamus (DMH). The exact...

Neurons in the superficial layers of the midbrain superior colliculus (SC) exhibit distinct tuning properties for visual stimuli, but, unlike neurons in the geniculocortical visual pathway, most respond best to visual stimuli that are smaller than the classical receptive field (RF). The mechanism underlying this size selectivity may depend on the number and pattern of feedforward retinal inputs...

Orexins are neuropeptides produced in the lateral hypothalamus and implicated in regulation of sleep-wake cycle. Selective loss of orexin neurons is found in the brain of patients with narcolepsy, but the mechanisms of this pathological change are unclear. A previous study showed that excessive stimulation of N-methyl-d-aspartate (NMDA) receptors by quinolinic acid (QA) caused selective loss of...

1. To determine the functional transformation in the processing step between lateral geniculate nucleus (LGN) and striate cortex, the receptive-field characteristics of 50 directly driven, lamina 4 S-cells were compared with those of a similar number of LGN neurons. Experiments were performed on paralyzed and anesthetized adult cats. 2. A signature was established for the responses of LGN neuro...

background: in vitro model studies are becoming increasingly popular for experimental research designs. they include isolation and expansion of cells of a particular tissue, such as the nervous tissue which contributes to understanding the underlying mechanisms in many pathologies. it enables  the scrutinization of intracellular signaling pathways responsible for cell death. objectives: in the ...

a new approach is introduced to estimate the formal information of neurons. formal information, mainly discusses about the aspects of the response that is related to the stimulus. estimation is based on introducing a mathematical nonlinear model with hammerstein-wiener system estimator. this method of system identification consists of three blocks to completely describe the nonlinearity of inpu...

the role of endogenous histamine and h1, h2 and h3 central receptors on food intake in broiler chickenswas investigated. for this purpose, a probe was used to manipulate the concentration of endogenoushistamine by intracerebroventricular (icv) injection of thioperamide, an h3 receptor antagonist, and r-α-methylhistamine, an h3 receptor agonist and subsequently the effects of brain histaminergic...

introduction mdma or ecstasy is a derivative of amphetamines used mostly by young people worldwide. although the acute effects of this drug are known, the effect of chronic administration is not well studied. therefor the aim of this study was to determine the effects of repeated (long term) administration of mdma on rats' memory and their hippocampal cell density. method: young adult male...