Long-term adaptation to ocular aberrations alters visual processing of spatial frequency information

The existence of multiple channels, or multiple receptive field sizes, in the visual system does not commit us to any particular theory of spatial encoding in vision. However, distortions of apparent spatial frequency and width in a wide variety of conditions favour the idea that each channel carries a width- or frequency-related code or ‘label’ rather than a ‘local sign’ or positional label. When distortions of spatial frequency occur without prior adaptation (e.g. at low contrast or low luminance) they are associated with lowered sensitivity, and may be due to a mismatch between the perceptual labels and the actual tuning of the channels. A low-level representation of retinal space could be constructed from the spatial information encoded by the channels, rather than being projected intact from the retina.

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Glutamate in the pathophysiology of schizophrenia

Psychotic Disorders ◽

10.1093/med/9780190653279.003.0032 ◽

2020 ◽

pp. 287-296

Author(s):

Daniel C. Javitt

Keyword(s):

Visual System ◽

Visual Processing ◽

Negative Symptoms ◽

Glutamate Release ◽

Critical Role ◽

Brain Regions ◽

Long Term Memory ◽

Subcortical Structures ◽

Impaired Metabolism

Glutamate theories of schizophrenia were first proposed over 30 years ago and since that time have become increasingly accepted. Theories are supported by the ability of N-methyl-D-aspartate receptor (NMDAR) antagonists such as phencyclidine (PCP) or ketamine to induce symptoms that closely resemble those of schizophrenia. Moreover, NMDAR antagonists uniquely reproduce the level of negative symptoms and cognitive deficits observed in schizophrenia, suggesting that such models may be particularly appropriate to poor outcome forms of the disorder. As opposed to dopamine, which is most prominent within frontostriatal brain regions, glutamate neurons are present throughout cortex and subcortical structures. Thus, NMDAR theories predict widespread disturbances across cortical and thalamic pathways, including sensory brain regions. In auditory cortex, NMDAR play a critical role in the generation of mismatch negativity (MMN), which may therefore serve as a translational marker of NMDAR dysfunction across species. In the visual system, NMDAR play a critical role in function of the magnocellular visual system. Deficits in both auditory and visual processing contribute to social and communication deficits, which, in turn, lead to poor functional outcome. By contrast, NMDAR dysfunction within the frontohippocampal system may contribute to well described deficits in working memory, executive processing and long-term memory formation. Deficits in NMDAR function may be driven by disturbances in presynaptic glutamate release, impaired metabolism of NMDAR modulators such as glycine or D-serine, or intrinsic abnormalities in NMDAR themselves.

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No Sex Differences in Contrast Sensitivity and Reaction Time to Spatial Frequency

Perceptual and Motor Skills ◽

10.2466/pms.2002.94.3.1053 ◽

2002 ◽

Vol 94 (3) ◽

pp. 1053-1055 ◽

Cited By ~ 7

Author(s):

Jennifer L. Solberg ◽

James M. Brown

Keyword(s):

Sex Differences ◽

Reaction Time ◽

Spatial Frequency ◽

Contrast Sensitivity ◽

Frequency Information ◽

Frequency Processing

This study investigated the possibility of sex differences in spatial frequency processing by measuring contrast sensitivity and reaction time to spatial frequency in the same 20 men and 20 women. This is the first study to investigate sex differences in reaction time to spatial frequency and the first to study sex differences in contrast sensitivity and reaction time within the same participants. No sex differences were found in either contrast sensitivity or reaction time measures, suggesting that women and men process spatial frequency information similarly.

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Sounds prevent selective monitoring of high spatial frequency channels in vision

Seeing and Perceiving ◽

10.1163/187847612x646622 ◽

2012 ◽

Vol 25 (0) ◽

pp. 40

Author(s):

Alexis Pérez-Bellido ◽

Joan López-Moliner ◽

Salvador Soto-Faraco

Keyword(s):

Standard Deviation ◽

Spatial Frequency ◽

Visual Processing ◽

Reaction Times ◽

High Spatial Frequency ◽

Visual Signals ◽

Sensory Interactions ◽

Multisensory Interactions ◽

Visual Targets ◽

Selective Monitoring

Prior knowledge about the spatial frequency (SF) of upcoming visual targets (Gabor patches) speeds up average reaction times and decreases standard deviation. This has often been regarded as evidence for a multichannel processing of SF in vision. Multisensory research, on the other hand, has often reported the existence of sensory interactions between auditory and visual signals. These interactions result in enhancements in visual processing, leading to lower sensory thresholds and/or more precise visual estimates. However, little is known about how multisensory interactions may affect the uncertainty regarding visual SF. We conducted a reaction time study in which we manipulated the uncertanty about SF (SF was blocked or interleaved across trials) of visual targets, and compared visual only versus audio–visual presentations. Surprisingly, the analysis of the reaction times and their standard deviation revealed an impairment of the selective monitoring of the SF channel by the presence of a concurrent sound. Moreover, this impairment was especially pronounced when the relevant channels were high SFs at high visual contrasts. We propose that an accessory sound automatically favours visual processing of low SFs through the magnocellular channels, thereby detracting from the potential benefits from tuning into high SF psychophysical-channels.

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The importance of low spatial frequency information for recognising fearful facial expressions

Connection Science ◽

10.1080/09540090802213974 ◽

2009 ◽

Vol 21 (1) ◽

pp. 75-83 ◽

Cited By ~ 27

Author(s):

Martial Mermillod ◽

Patrik Vuilleumier ◽

Carole Peyrin ◽

David Alleysson ◽

Christian Marendaz

Keyword(s):

Spatial Frequency ◽

Facial Expressions ◽

Frequency Information

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Corpus callosum has different channels for transmission of spatial frequency information

Brain Research ◽

10.1016/j.brainres.2009.08.018 ◽

2009 ◽

Vol 1296 ◽

pp. 85-93 ◽

Cited By ~ 10

Author(s):

Canan Kalaycıoğlu ◽

Erhan Nalçacı ◽

Christina Schmiedt-Fehr ◽

Canan Başar-Eroğlu

Keyword(s):

Corpus Callosum ◽

Spatial Frequency ◽

Frequency Information

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