7
Short answer
The auditory system remains active during sleep.
Background
Filtering of sensory input during sleep is a recognized phenomenon and indeed the senses are typically lulled during sleep. This phenomenon is, at least partly, caused by thalamic gating. Thalamic gating is caused by the thalamus entering a state in which slow-wave activity disrupts ...
6
Generally spoken, synesthesia is unidirectional. For example, grapheme–color synesthesia (i.e., letter–color and digit–color synesthesia) is the most prevalent type of synesthesia. The presentation of a
grapheme leads to an additional synesthetic color percept. Although
grapheme–color synesthetes are strongly influenced by the synesthetic color perception ...
5
Psychology and physiology are at different levels of explanation or levels of analysis. The answer depends entirely on how you view the relationship between such levels and in particular (mental) causality within and between levels. As this is still heavily debated, this metaphysical consideration is a precursor for giving a more specific answer to your ...
5
Short answer
Sensations are different from thoughts and are separated in the spatial and temporal domain. The distinction between thoughts and perceptions, however, is less well defined, but can still be dealt with experimentally.
Background
A description of sensation is as follows:
The physical process during which our sensory organs [...] respond to
...
5
In general, subjective sensation increases linearly with the the log of physical intensity, which is described by Fechner's law.
We are sensitive to small variations when light is dim, but we need large differences in intensity under conditions of high luminance (Weber's law). This is a linear relation, but taken together with Fechner these findings are ...
4
I think you are confusing speed with rate. The speed of light is how long it take to for light to get from one point to another, not how often light "events" arrive at the eye.
To give an analogy, imagine a highway. There are 500 cars on that highway. They are traveling at 70 mph. Those cars then exit the highway onto a residential rode. They are ...
4
The difference is in whether the animal has voluntary control over the touch. If the animal touches another object by moving its body to initiate the touch, then the it is active touch. If the animal is touched without control over the movement (for example, a human experimenter grazing the whiskers with a finger), then the touch is passive.
4
As far as I know, there is just one article that explicitly mentions the generation of cross-modal qualia, i.e., visual qualia in response to tactile stimulation (Ortiz et al., 2011). Before continuing about this article I do wish to emphasize it is a single, isolated study that hasn't been supported by other studies at the time of this writing. Moreover, ...
3
Is there knowledge of the receptive field patterns of cortical columns in associative brain regions?
Short answer
Associative brain areas are not retinotopically organized. Only lower visual areas more upstream from these areas are organized in such a predictable, low-level way. Higher up, things get complicated and unpredictable.
Background
Visual receptive fields and retinotopy are generally well-preserved in the periphery and subcortical areas (e.g. in ...
3
Short answer
No, infrasonic or ultrasonic sound cannot generate binaural beats.
Background
Binaural beats are generated in the brain and are associated with the frequency bands of the EEG. Binaural beats in the delta (1 to 4 Hz) and theta (4 to 8 Hz) ranges have reportedly been associated with reports of relaxed, meditative, and creative states, and used ...
3
It depends on ambient light, but in darkness, humans can detect as few as several photons, perhaps even down to a single photon (though all detection at these low levels is probabilistic - see Tinsley et al, 2016).
Therefore, this depends on the ambient light (ideal detection in darkness), and the number of photons. At this level of detection, it doesn't ...
3
Sound is pressure waves; young humans can hear (aka, detect pressure waves) up to about 20 kHz. To produce these high frequency waves with a speaker with a time-domain signal, it is necessary to have a sampling rate at least 2x the highest frequency that will be represented. In practice, those very high frequencies aren't included in music, and definitely ...
2
Short answer
It may not be so much the direct action of DMSO on the olfactory sensory system, but the smell of one of its metabolites that is excreted via the pulmonary system and the skin after ingestion of DMSO.
Background
Dimethyl sulfoxide (DMSO) is metabolized in man by oxidation to dimethyl sulfone (MSM) or by reduction to dimethyl sulfide (DMS) (Fig....
2
Short answer
Yes, retinal circuitry enhances the perception of contrast.
Background
In the retina, the neurons that guide the visual signal to the brain, the retinal ganglion cells (RGCs), process contrast. The receptive fields (RFs) of these cells exhibit a so-called center-surround organization (Fig. 1). They integrate the signal from multiple cones in ...
2
Here’s an image I found that triggers tristable perception (as opposed to just bistable perception):
The three possible interpretations are
A big cube with a smaller cube in front of it
A big cube with a small cubical chunk missing
A room with a small cube sitting in the corner
Apparently there is a fourth possible interpretation, but it is so “unlikely” ...
2
I don't have a full answer, but it might get things started...
You are mixing up two concepts frame rate and sampling rate. In a video presented at 24 fps each frame, potentially, has a wide range of spatial frequencies. Typically the spatial frequencies are limited by the number of pixels, but you can low pass filter each frame to reduce the spatial ...
2
The synchronization of sensory information is called multisensory integration:
Multisensory integration, also known as multimodal integration, is the
study of how information from the different sensory modalities (such
as sight, sound, touch, smell, self-motion, and taste) may be
integrated by the nervous system.
This is the most salient example of ...
2
Short answer
The brain actively integrates and synchronizes sensory inputs, up to the point that it actually delays one modality to match it with another.
Background
Your question is all about intersensory asynchrony and sensory integration.
A well-known example where the two stimulus modalities you mention in your question (light and sound) are perceived ...
1
The question you ask is the topic of a very active line of research.
First you are right that light (~300.10^6m.s-1) and sounds (~350m.s-1) reach an observer at different times, as a function of distance. You are also right that visual and auditory inputs are processed at different speeds by the brain, with auditory signals being faster. The auditory system ...
1
Short answer
Multi-channel coding in color vision refers to the different photoreceptors in the retina.
Opponent-channel coding refers to the opposing color pairs: the red-green and yellow-blue axes.
Background
I think you are referring to terminologies often used in color vision.
Multi-channel coding generally refers to different types of ...
1
No, the carrier frequency for a binaural beat needs to be less than approximately 1500 Hz. The binaural beat arises because when two tones with slightly different frequencies are added, the instantaneous phase of the combination tone varies with time and has a period equal to the difference of the tones. The generation of the binaural beat therefore requires ...
1
You are basically asking how to bind different concepts together based off their representation in neurons. The one way I know how to do this is using the Semantic Pointer Architecture (SPA).
To understand how lower level neural activities can be compressed as a concept, please see my answer on compression in the brain using the SPA. This answer explains ...
1
Two ideas on this so far:
I think we have neurons representing multiple occurrences of a given feature, for example one neuron for "one face", one for "two faces", etc. At some number it doesn't really make a big difference anymore, so there is just a neuron for "group of faces". This would explain why we can recognize small number of objects in a glimpse ...
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