scholarly journals Contrast sensitivity and behavioural evidence for lateral inhibition in octopus

2019 ◽  
Vol 15 (5) ◽  
pp. 20190134 ◽  
Author(s):  
Luis Nahmad-Rohen ◽  
Misha Vorobyev
Keyword(s):  
Spatial Frequency ◽  
Contrast Sensitivity ◽  
Lateral Inhibition ◽  
Neural Processing ◽  
Visual Systems ◽  
Maximum Value ◽  
Fixation Reflex ◽  
First Time ◽  
The Brain ◽  
Behavioural Evidence

Behavioural contrast sensitivity in Octopus tetricus was measured in the range of 0.05–12 cycles per degree (cpd) using a fixation reflex. We show that the contrast sensitivity reaches its maximum (between 1 and 4%) at 0.3 cpd, and decreases to approximately half of the maximum value at the lowest spatial frequency. Reduction of sensitivity at low spatial frequency is a signature of lateral inhibition in visual systems. In vertebrates and insects, lateral inhibition helps to overcome the bottleneck of encoding information into spikes. In octopus, photoreceptors generate spikes themselves and are directly connected to the brain through their axons. Therefore, the neural processing occurring in the octopus brain cannot help overcome the bottleneck of encoding information into spikes. We conclude that, in octopus, either the lateral inhibition occurs in the brain after information has been encoded into spikes, or photoreceptors inhibit each other. This is the first time behavioural contrast sensitivity has been measured in a cephalopod.

scholarly journals Rapid Temporal Recalibration to Audiovisual Asynchrony Occurs Across the Difference in Neural Processing Speed Based on Spatial Frequency

i-Perception ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 204166952096661
Author(s):  
Yasuhiro Takeshima
Keyword(s):  
Spatial Frequency ◽  
Processing Speed ◽  
Audiovisual Integration ◽  
Auditory Stimuli ◽  
Neural Processing ◽  
Temporal Recalibration ◽  
Synchrony Perception ◽  
The Difference ◽  
The One ◽  
The Brain

Audiovisual integration relies on temporal synchrony between visual and auditory stimuli. The brain rapidly adapts to audiovisual asynchronous events by shifting the timing of subjective synchrony in the direction of the leading modality of the most recent event, a process called rapid temporal recalibration. This phenomenon is the flexible function of audiovisual synchrony perception. Previous studies found that neural processing speed based on spatial frequency (SF) affects the timing of subjective synchrony. This study examined the effects of SF on the rapid temporal recalibration process by discriminating whether the presentation of the visual and auditory stimuli was simultaneous. I compared the magnitudes of the recalibration effect between low and high SF visual stimuli using two techniques. First, I randomly presented each SF accompanied by a tone during one session, then in a second experiment, only a single SF was paired with the tone throughout the one session. The results indicated that rapid recalibration occurred regardless of difference in presented SF between preceding and test trials. The recalibration magnitude did not significantly differ between the SF conditions. These findings confirm that intersensory temporal process is important to produce rapid recalibration and suggest that rapid recalibration can be induced by the simultaneity judgment criterion changes attributed to the low-level temporal information of audiovisual events.

Flicker Contrast Sensitivity in Normal and Specifically Disabled Readers

Perception ◽  
1987 ◽  
Vol 16 (2) ◽  
pp. 215-221 ◽  
Author(s):  
Frances Martin ◽  
William Lovegrove
Keyword(s):  
Spatial Frequency ◽  
Contrast Sensitivity ◽  
Temporal Frequency ◽  
Temporal Contrast ◽  
Control Subjects ◽  
Visual Systems ◽  
Spatial Frequencies ◽  
Disabled Readers ◽  
Transient System

Temporal contrast sensitivity for counterphase flicker was determined for specifically disabled and normal readers to investigate whether the two groups differ in the functioning of their transient systems. In experiment 1, temporal contrast sensitivity was measured over a range of temporal frequencies with a spatial frequency of 2 cycles deg−1. Disabled readers were less sensitive than the control subjects at all temporal frequencies. In experiment 2, temporal contrast sensitivity was measured at a temporal frequency of 20 Hz over a range of spatial frequencies. Disabled readers were less sensitive than the controls at all spatial frequencies, with the differences between the groups increasing as spatial frequency increased. Both these findings are interpreted as supporting the hypothesis of a transient-system deficit in the visual systems of disabled readers.

Behavioral determination of the spatial selectivity of contrast adaptation in cats: Some evidence for a common plan in the mammmlian visual system

1990 ◽  
Vol 4 (05) ◽  
pp. 413-426 ◽  
Author(s):  
M.A. Berkley
Keyword(s):  
Spatial Frequency ◽  
Contrast Sensitivity ◽  
Striate Cortex ◽  
Frequency Tuning ◽  
Spatial Vision ◽  
Adaptation Effect ◽  
Test Grating ◽  
Contrast Adaptation ◽  
Visual Systems ◽  
Spatial Frequencies

AbstractAn aftereffects paradigm was used to behaviorally measure contrast sensitivity of cats to gratings of three different test spatial frequencies after adaptation to gratings of various spatial frequencies, contrasts, and durations. Post-adaptation reductions in sensitivity occurred even after short periods of adaptation (<7 s) and could be as large as 1.0 log unit under some conditions. The magnitude of the adaptation effect varied monotonically with (1) adaptation grating contrast, (2) duration, and (3) the contrast sensitivity for the test grating. Average half-width (at half-height) of the spatial-frequency tuning curves constructed from the data was 1.4 octaves, and was not dependent upon the level of adaptation or the spatial frequency of the test grating. Post-adaptation psychometric functions of the cats showed reduced slopes and maxima suggesting that, unlike humans, in cats apparent contrast grows more slowly with increases in physical contrast after contrast adaptation. All of the characteristics observed are in excellent agreement with electrophysiologically measured properties of neurons in striate cortex of cats. In addition, there was a remarkable similarity of the cat tuning functions, both in shape and bandpass, to those measured in man with a similar paradigm suggesting that (1) the two visual systems are sufficiently similar to make the cat a useful spatial vision model and (2) there is a common functional plan to all mammalian visual systems despite significant anatomical differences between species.

Magnetoencephalography and the Cortical Dynamics of Language Processing

2019 ◽  
pp. 114-153
Author(s):  
Riitta Salmelin ◽  
Jan Kujala ◽  
Mia Liljeström
Keyword(s):  
Language Processing ◽  
Language Disorders ◽  
Scientific Data ◽  
Neural Processing ◽  
Powerful Method ◽  
Cortical Dynamics ◽  
Brain Correlates ◽  
Adults And Children ◽  
The Brain ◽  
Selection Of

When seeking to uncover the brain correlates of language processing, timing and location are of the essence. Magnetoencephalography (MEG) offers them both, with the highest sensitivity to cortical activity. MEG has shown its worth in revealing cortical dynamics of reading, speech perception, and speech production in adults and children, in unimpaired language processing as well as developmental and acquired language disorders. The MEG signals, once recorded, provide an extensive selection of measures for examination of neural processing. Like all other neuroimaging tools, MEG has its own strengths and limitations of which the user should be aware in order to make the best possible use of this powerful method and to generate meaningful and reliable scientific data. This chapter reviews MEG methodology and how MEG has been used to study the cortical dynamics of language.

Information-based decoding of the coupling among human brain activity and movement paths

2021 ◽  
pp. 1-10
Author(s):  
Shahul Mujib Kamal ◽  
Norazryana Mat Dawi ◽  
Hamidreza Namazi
Keyword(s):  
Brain Activity ◽  
Point Of View ◽  
Physiological Signals ◽  
Human Walking ◽  
Eeg Signals ◽  
Rehabilitation Science ◽  
Information Contents ◽  
First Time ◽  
The Brain ◽  
Brain Reaction

BACKGROUND: Walking like many other actions of a human is controlled by the brain through the nervous system. In fact, if a problem occurs in our brain, we cannot walk correctly. Therefore, the analysis of the coupling of brain activity and walking is very important especially in rehabilitation science. The complexity of movement paths is one of the factors that affect human walking. For instance, if we walk on a path that is more complex, our brain activity increases to adjust our movements. OBJECTIVE: This study for the first time analyzed the coupling of walking paths and brain reaction from the information point of view. METHODS: We analyzed the Shannon entropy for electroencephalography (EEG) signals versus the walking paths in order to relate their information contents. RESULTS: According to the results, walking on a path that contains more information causes more information in EEG signals. A strong correlation (p= 0.9999) was observed between the information contents of EEG signals and walking paths. Our method of analysis can also be used to investigate the relation among other physiological signals of a human and walking paths, which has great benefits in rehabilitation science.

scholarly journals Biosynthesis of anandamide and N-palmitoylethanolamine by sequential actions of phospholipase A2 and lysophospholipase D

2004 ◽  
Vol 380 (3) ◽  
pp. 749-756 ◽  
Author(s):  
Yong-Xin SUN ◽  
Kazuhito TSUBOI ◽  
Yasuo OKAMOTO ◽  
Takeharu TONAI ◽  
Makoto MURAKAMI ◽  
...  
Keyword(s):  
Biosynthetic Pathway ◽  
Brain Homogenate ◽  
Wide Distribution ◽  
Rat Tissues ◽  
Lysophospholipase D ◽  
Pla2 Enzyme ◽  
First Time ◽  
Hydrolysis Of ◽  
The Brain

Anandamide (an endocannabinoid) and other bioactive long-chain NAEs (N-acylethanolamines) are formed by direct release from N-acyl-PE (N-acyl-phosphatidylethanolamine) by a PLD (phospholipase D). However, the possible presence of a two-step pathway from N-acyl-PE has also been suggested previously, which comprises (1) the hydrolysis of N-acyl-PE to N-acyl-lysoPE by PLA1/PLA2 enzyme(s) and (2) the release of NAEs from N-acyllysoPE by lysoPLD (lysophospholipase D) enzyme(s). In the present study we report for the first time the characterization of enzymes responsible for this pathway. The PLA1/PLA2 activity for N-palmitoyl-PE was found in various rat tissues, with the highest activity in the stomach. This stomach enzyme was identified as group IB sPLA2 (secretory PLA2), and its product was determined as N-acyl-1-acyl-lysoPE. Recombinant group IB, IIA and V of sPLA2s were also active with N-palmitoyl-PE, whereas group X sPLA2 and cytosolic PLA2α were inactive. In addition, we found wide distribution of lysoPLD activity generating N-palmitoylethanolamine from N-palmitoyl-lysoPE in rat tissues, with higher activities in the brain and testis. Based on several lines of enzymological evidence, the lysoPLD enzyme could be distinct from the known N-acyl-PE-hydrolysing PLD. sPLA2-IB dose dependently enhanced the production of N-palmitoylethanolamine from N-palmitoyl-PE in the brain homogenate showing the lysoPLD activity. N-Arachidonoyl-PE and N-arachidonoyl-lysoPE as anandamide precursors were also good substrates of sPLA2-IB and the lysoPLD respectively. These results suggest that the sequential actions of PLA2 and lysoPLD may constitute another biosynthetic pathway for NAEs, including anandamide.

NO nerves in a tapeworm. NADPH-diaphorase histochemistry in adult Hymenolepis diminuta

Parasitology ◽  
1996 ◽  
Vol 113 (6) ◽  
pp. 559-565 ◽  
Author(s):  
M. K. S. Gustafsson ◽  
A. M. Lindholm ◽  
N. B. Terenina ◽  
M. Reuter
Keyword(s):  
Nitric Oxide ◽  
Nervous System ◽  
Nadph Diaphorase ◽  
Hymenolepis Diminuta ◽  
Staining Reaction ◽  
Internal Seminal Vesicle ◽  
Oxide Synthase ◽  
First Time ◽  
The Brain ◽  
Nerve Cords

SUMMARYThe free radical nitric oxide (NO), which is synthesized by nitric oxide synthase (NOS), has recently been discovered to function as a neuronal messenger. The presence of NOS was detected in the nervous system of adult Hymenolepis diminuta with NADPH-diaphorase (NADPH-d) histochemistry. The NADPH-d histochemical reaction is regarded as a selective marker for NOS in neuronal tissue. NADPH-d staining was observed in nerve fibres in the main and minor nerve cords and the transverse ring commissures, and in cell bodies in the brain commissure, along the main nerve cords, in the suckers and the rostellar sac. NADPH-d staining was also observed in the wall of the internal seminal vesicle and the genital atrium. The pattern of NADPH-d staining was compared with that of the 5-HT immunoreactive nervous elements. The NADPH-d staining reaction and the 5-HT immunoreactivity occur in separate sets of neurons. This is the first time the NADPH-d reaction has been demonstrated in the nervous system of a flatworm, indicating that NOS is present and that NO can be produced at this level of evolution.

Cocaine Dependence Produce Psychiatric Symptoms - a Case Report

2009 ◽  
Vol 24 (S1) ◽  
pp. 1-1
Author(s):  
M. Stankovic ◽  
S. Vucetic-Arsic ◽  
S. Alcaz ◽  
J. Cvejic
Keyword(s):  
Clinical Features ◽  
Male Patient ◽  
Psychiatric Symptoms ◽  
Cocaine Dependence ◽  
Psychotic Symptoms ◽  
Personal Contact ◽  
Outpatient Unit ◽  
Special Hospital ◽  
First Time ◽  
The Brain

Aim:We want to present a polymorphic clinical features like: hallutinations, paranoid ideas, agitation and violence as a result of prolonged cocaine intranasal consumption.Methods:We exposed a 30-year old male patient with ICD-X diagnostic criteria for cocaine dependence (intranasal consumption) that treated in the outpatient unit of Special Hospital of Addicitons, Belgrade, Serbia from April to July 2008. We used the medical records, psychical examination, psychiatric interwievs, standard blood sampling and cocaine urine detections sample (positive).Results:Observations a specific and polymorphic clinical features with presence of psychotic symptoms after cocaine consumptions in our male patient, for the first time after 5 years of cocaine dependence: auditory hallucinations (two- voice speakers), paranoid persecution ideas and suspiciousness, agitation with appearance of vegetative symptomatology (palpitations, sweating, pupil dilatation), extremely violence behavior to other people, complete social reductions (“armed to the outside world”, refused any personal contact and isolated from friends and family, permanent outdoor checking). There was an intensive fear too and impaired judgment.Conclusions:Permanent cocaine consumption can result with produce a numerous of psychiatric symptoms and syndromes as our experience does. It is similar to the findings of other studies and papers reviewed. It is suppose that cocaine has numerous effects on important neurotransmitters in the brain, such as increase as well as the release of dopamine and it related with aggressiveness, hallucinations and other psychiatric symptoms.

Information-based analysis of the coupling between brain and heart reactions to olfactory stimulation

2021 ◽  
pp. 1-11
Author(s):  
Najmeh Pakniyat ◽  
Mohammad Hossein Babini ◽  
Vladimir V. Kulish ◽  
Hamidreza Namazi
Keyword(s):  
Time Series ◽  
Biomedical Science ◽  
Strongly Correlated ◽  
Eeg Signals ◽  
Ecg Signals ◽  
Olfactory Stimuli ◽  
Electrocardiogram Ecg ◽  
First Time ◽  
Electroencephalogram Eeg ◽  
The Brain

BACKGROUND: Analysis of the heart activity is one of the important areas of research in biomedical science and engineering. For this purpose, scientists analyze the activity of the heart in various conditions. Since the brain controls the heart’s activity, a relationship should exist among their activities. OBJECTIVE: In this research, for the first time the coupling between heart and brain activities was analyzed by information-based analysis. METHODS: Considering Shannon entropy as the indicator of the information of a system, we recorded electroencephalogram (EEG) and electrocardiogram (ECG) signals of 13 participants (7 M, 6 F, 18–22 years old) in different external stimulations (using pineapple, banana, vanilla, and lemon flavors as olfactory stimuli) and evaluated how the information of EEG signals and R-R time series (as heart rate variability (HRV)) are linked. RESULTS: The results indicate that the changes in the information of the R-R time series and EEG signals are strongly correlated (ρ=-0.9566). CONCLUSION: We conclude that heart and brain activities are related.

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