Some biological aspects of Gammarus lacustris Sars, 1863 in Neur Lake Ardabeel province, Iran

A biological study was conducted to find out about reproduction and feeding of G. lacustris in Neur Lake from northwest mountains of Iran. Plankton diversity, hydro-chemical factors and substrate characteristic were recorded monthly. Findings showed that reproduction period of this species was short and limited to May and the mean brood size was 10.2 ± 5.3 eggs per female. The hydro-chemical analysis showed the eutrophic characteristic of Neur Lake in which the average of total organic matter was 3.7 ± 3.0 percent. The phyla representative Bacillariophyta, Chlorophyta and Cyanophyta were observed throughout the study and Chlorophyta was the dominant group. Three zooplankton phyla Rotatoria, Ciliophora and Copepoda were abundant respectively. Study on diet using gut content resulted in identification of 15 plankton genera with some resemblance to planktons of the lake

The mammals of Anzali Wetland in the Southern Caspian Sea

Anzali Wetland as a listed habitat in Montreux Record, was investigated for the mammal fauna during Jan. 2015 - Jan. 2016. About 165 km of water bodies and 200 km around Anzali Wetland were patrolled, respectively. By applying different methods, such as direct observation, different signs recording, using different sampling traps,nets and camera traps, twenty mammal species were identified from 5 orders and 13 families. While Wild boar,Golden Jackal and Common otter were widely distributed, Common badger, Asiatic wildcat and Jungle cat were observed in some parts of this wetland. Six rodent species were recognized in different parts of the wetland. Among four identified bat species, Nathusius’s pipistrelle has been reported only from this region in Iran. The most commonly recorded bat species was the Soprano pipistrelle, a species hereto recorded only from two Iranian localities. Two recognized species from order Eulipotyphla; Caspian shrew and a mysterious mole are important due to their narrow geographical distribution range as well as their taxonomic situation. Although there was no quantitative or qualitative data from the past, our results show that the situation of many mammal species are not suitable, and some of them are being increasingly threatened

State of Mnemiopsis leidyi (Ctenophora: Lobata) and mesozooplankton in Iranian waters of the Caspian Sea during 2008 in comparison with previous surveys

Mnemiopsis leidyi which was accidentally introduced into the Caspian Sea in 1999 and since then has colonized extensively. The horizontal distribution of M. leidyi and dominant mesozooplankton species was investigated in the south western Caspian Sea during February, May, July and November 2008. The average number and biomass of M. leidyi were in the same range (ca 200 individuals m^-3 (2000 ind m^-2)) and 16 g wet weight m^-3 (180 g m^-2) in comparison with previous surveys. As in previous years the population consisted mainly of individuals <1 cm. The decline in mesozooplankton species observed since 1996 continued in 2008. Only two species of the previously recorded 24 Cladocera species were found in 2008. Of five Copepoda species recorded in 1996, only one, Acartia tonsa, was found in 2008 and even here adult individuals have reduced 3-fold since 1996. Bivalve larvae have declined by one order of magnitude since 1996. Among the dominant species, only the numbers of Cirripedia larvae and in part the numbers of Pleopis polyphemoides (Cladocera) were in the same range as in 1996

An fMRI study of human visual cortex in response to spatiotemporal properties of visual stimuli

Background: The brain response to temporal frequencies (TF) has been already reported, but with no study reported for different TF with respect to various spatial frequencies (SF). Materials and Methods: fMRI was performed by 1.5T GE-system in 14 volunteers during checkerboard, with TFs of 4, 6, 8 and 10Hz in low and high SFs of 0.5 and 8cpd. Results: Average percentage BOLD signal change demonstrated the amplitude of the fMRI response to different TFs was maximal in 6Hz for high SF of 8cpd, while, it was maximal at TF of 8Hz for low SF of 0.5cpd. Conclusion: The results are useful for vision therapy (such as the treatment Amblyopia) and visual task selecting in fMRI studies

Objective and subjective assessing efficacy of a lubricating drop in eyes wearing silicone hydrogel contact lenses

Purpose: To investigate the effect of a lubricating drop on optical quality, tear film stability, and subjective symptoms in individuals wearing silicone hydrogel contact lens. Methods: In this one-day, prospective single-center clinical study, Pre-lens Tear Deformation Time (PL-TDT), Root-Mean-Square (RMS) of Low Order Aberrations (LOA) and High Order Aberrations (HOA), individual twelve Zernike coefficients, and subjective symptoms were assessed in 43 volunteers (mean age 19.58 ± 1.63, 86 eyes) at 6 h after inserting the contact lens and then at 60 min after instilling a lubricating drop (Comfort drops, Avizor, Madrid-Spain). Results: PL-TDT, LOA-RMS, and HOA-RMS values measured before drop instillation were not significantly different with those measured after drop. None of the Zernike coefficients were significantly different after instilling lubricating drop. Statistically significant decrement in both frequency and severity values in blurry vision, dryness, discomfort, burning, itching, foreign body sensation, excessive blinking, and lacrimation were seen after drop instillation (all P < 0.05). Conclusion: Our results showed that although the lubricating drop did not improve the tear film stability and optical quality in the silicone hydrogel contact lens wearers, subjects experienced a subjective improvement. © 2016 Iranian Society of Ophthalmology

Spatial frequency modulates visual cortical response to temporal frequency variation of visual stimuli: An fMRI study

The brain response to temporal frequency (TF) variation has already been reported, but with no study for different TF with respect to various spatial frequencies (SF). Functional magnetic resonance imaging (fMRI) was performed with a 1.5 Tesla General Electric system in 14 volunteers during square-wave reversal checkerboard visual stimulation with different temporal frequencies of 4, 6, 8 and 10 Hz in two states of low SF of 0.4 and high SF of 8 cpd (cycles/degree). The activation map was created using the data obtained from the block-designed fMRI study. Voxels whose Z value was above a threshold of 3.0, at a significance level P = 0.05, were considered activated. The results demonstrated that the percentage BOLD signal change in response to different TFs was the maximum value at 6 Hz for a high SF of 8 cpd, whereas it was the maximum at TF of 8 Hz for a low SF of 0.4 cpd. The results of this study agree with the results of animal invasive neurophysiological studies showing spatial and temporal frequency selectivity of neurons in visual cortical areas. These results can be useful for vision therapy (such as the treatment of amblyopia) and selecting a visual task in fMRI studies. © 2007 IOP Publishing Ltd

Comparison of two methods for measuring contrast sensitivity in anisometropic amblyopia

Purpose: This study aimed to evaluate two psychophysical contrast sensitivity testing methods in amblyopic patients. Methods: Thirty-three adults with anisometropic amblyopia participated in this study. Psychophysical contrast sensitivity was measured for both amblyopic and fellow eyes of the participants at 1, 3, and 5 cycles per degree (cpd) spatial frequencies by Freiburg visual acuity and contrast test (FrACT) and Metrovision contrast sensitivity test, which employ sine-wave gratings for measurement of contrast sensitivity. We evaluated the correlation between the two tests and used Bland�Altman analysis to measure the agreement between the two methods. Results: Except for 1 cpd in amblyopic eyes, FrACT showed significantly higher contrast sensitivity measurements than Metrovision at all spatial frequencies both in normal and amblyopic eyes (P < 0.01). The difference between the two methods increased with an increase in spatial frequency. There was a significant correlation between the two tests at most of the spatial frequencies. While the difference between the results of the two tests increased with an increase in contrast sensitivity in amblyopic eyes, we found an inter-test agreement in normal eyes. Conclusion: Although both FrACT and Metrovision employ sine-wave gratings to measure contrast sensitivity, there are some differences between them, and their results cannot be used interchangeably. © 2018 Iranian Society of Ophthalmolog

Comparison of two methods for measuring contrast sensitivity in anisometropic amblyopia

Purpose: This study aimed to evaluate two psychophysical contrast sensitivity testing methods in amblyopic patients. Methods: Thirty-three adults with anisometropic amblyopia participated in this study. Psychophysical contrast sensitivity was measured for both amblyopic and fellow eyes of the participants at 1, 3, and 5 cycles per degree (cpd) spatial frequencies by Freiburg visual acuity and contrast test (FrACT) and Metrovision contrast sensitivity test, which employ sine-wave gratings for measurement of contrast sensitivity. We evaluated the correlation between the two tests and used Bland�Altman analysis to measure the agreement between the two methods. Results: Except for 1 cpd in amblyopic eyes, FrACT showed significantly higher contrast sensitivity measurements than Metrovision at all spatial frequencies both in normal and amblyopic eyes (P < 0.01). The difference between the two methods increased with an increase in spatial frequency. There was a significant correlation between the two tests at most of the spatial frequencies. While the difference between the results of the two tests increased with an increase in contrast sensitivity in amblyopic eyes, we found an inter-test agreement in normal eyes. Conclusion: Although both FrACT and Metrovision employ sine-wave gratings to measure contrast sensitivity, there are some differences between them, and their results cannot be used interchangeably. © 2018 Iranian Society of Ophthalmolog

Spatial frequency modulates the human visual cortical response to temporal frequency variation: An fMRI study

The brain response to temporal frequencies (TF) has been already reported, but with no study for different TFs with respect to various spatial frequencies (SF). Functional Magnetic Resonance Imaging (fMRI) was performed by 1.5 Tesla General Electric-system in 14 volunteers (9 males and 5 females, range 19-26 years) during square-wave reversal checkerboard visual stimulation with different temporal frequencies of 4, 6, 8 and 10 Hz in two states of low SF of 0.5 and high SF of 8 cpd (cycles/degree). The activation map was created using the data obtained from the block designed fMRI study. Pixels whose correlation coefficient value was above a threshold of 0.33, in significant level P <0.01 were considered activated. The average percentage BOLD (blood oxygenation level dependent) signal change for all activated pixels within the occipital lobe, multiplied by the total number of activated pixels within the occipital lobe, was used as the criterion for the strength of the fMRI signal at each state of TF& SF. The results demonstrated that the strength of the fMRI signal in response to different TFs was maximum in 6Hz for high SF of 8cpd, while it was maximum at TF of 8Hz for low SF of 0.5cpd. The results of this study agree with the results of animal invasive neurophysiological studies showing spatial and temporal frequency selectivity of neurons in visual cortical areas. These results can be useful for vision therapy (such as the treatment of Amblyopia) and selecting visual task in fMRI studies. © International Federation for Medical and Biological Engineering 2007