12 votes
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Can neuron change from excitatory to inhibitory (and vice versa) over time?

As far as I know, it is not possible for a neuron to change which type of neurotransmitter it releases. However, it is the case that the neurotransmitter GABA changes from excitatory to inhibitory ...
honi's user avatar
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8 votes
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Physiology behind EEG measurements

EEG research all started with Hans Berger, who in 1929 reported that brain activity could be recorded by measuring electrical activity on the scalp. Although the notion of ‘brain waves’ that were ...
Robin Kramer-ten Have's user avatar
8 votes
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Can you get sad by sniffing onions, just like you can get happy by forcing yourself to smile?

I assume you're referring to the experiment by Strack, Martin, and Stepper (1988) in which people rated a cartoon as funnier when they had to hold their face in a smile shape by gripping a pencil in ...
PhiloT's user avatar
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7 votes

If the color black reflects no light, how are we able to see it?

Objects are visually perceived when they reflect light. A black object does not reflect any light. In other words, no photons are reflected to be detected by the photoreceptors in the retina. A black ...
AliceD's user avatar
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7 votes

Can LSD connect sensory regions in the brain?

The phenomenon you are referring to is called synesthesia, which can be defined as (Sinke et al., 2012): Synesthesia (Greek: syn = together; aesthesis = perception) is [...] a crossing of sensory ...
AliceD's user avatar
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7 votes

How does the inner ear encode sound intensity?

Short answer Hair cells in the cochlea can code sound intensity via the amount of neurotransmitter they release. Higher sound levels result in more neurotransmitter release and in turn to higher ...
AliceD's user avatar
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7 votes

What is the computational role of the cortical column?

Cortical columns are groups of neurons in the brain that are oriented perpendicularly to the cortical surface. Cells within a column respond to the same stimulus property (Fig. 1). For example, ...
AliceD's user avatar
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7 votes
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What are the temporal limits of the auditory system?

As far as I know, auditory clicks are the shortest possible auditory stimuli. The shortest auditory click I was able to find in the literature, and which was used in a psychophysical context (i.e., ...
AliceD's user avatar
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7 votes
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How do hair cells recognize frequencies?

Short answer Population activity in auditory neurons allows rate coding of soundwaves with frequencies that exceed the firing rate limit. Place coding is, however, believed to be the most important ...
AliceD's user avatar
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6 votes

What advantages does a neuron with multiple dendrites have?

More dendritic input makes a neuron more suitable as an integrator. The more dendrites a neuron has, however, the less faithful it will transmit a single incoming signal, as other incoming input may ...
AliceD's user avatar
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6 votes

Does the split brain disprove a materialistic mind?

The question title reads: Does the split brain disprove a materialistic mind? The simple answer being no, nothing disproves that - the brain harbors the mind (e.g., Lilienfeld & Arkowitz, 2008). ...
AliceD's user avatar
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6 votes

What are the temporal limits of the auditory system?

In terms of the shortest stimuli, the auditory system can process acoustic impulses, but defining the duration of an impulse is problematic. As the duration of the impulse gets shorter, the bandwidth ...
StrongBad's user avatar
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6 votes
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What degree of control do we have on eye movements?

Short answer We have a lot of control over our eye movements, including saccades. We can suppress saccades and make an anti-saccade instead. So can monkeys, our close cousins. Children have a lot more ...
AliceD's user avatar
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5 votes

Can LSD connect sensory regions in the brain?

In a recent study, brain scans revealed that people under the influence of LSD experience images through information drawn from many parts of their brains, and not just the visual cortex at the back ...
John Slegers's user avatar
5 votes

Do direct cortical pathways exist in the visual system, or do they all go via the thalamus?

Short answer Intracortical projections can be routed directly to other cortical areas (cortico-cortical projections), or via the thalamus (cortico-thalamo-cortical projections). Background ...
AliceD's user avatar
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5 votes
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What regulates the strength of motor signals?

Short answer Muscles are controlled by motor neurons in the spinal cord. The number of motor neurons that fire, as well as their individual firing rates govern the control of muscle force. Background ...
AliceD's user avatar
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5 votes
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Can a hyperpolarized neuron fire action potentials?

Perhaps this is not what you asked, but there's a phenomenon called rebound spiking or postinhibitory spiking where a hyperpolarization causes spiking. This is due to the oscillatory property of ...
Memming's user avatar
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5 votes
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"Nested Neurons": Are they biologically plausible?

Disregarding the feasibility of neurons within neurons in silico, the answer to Is there any evidence for neurons existing within other neurons in humans or other organisms? from a practical, ...
AliceD's user avatar
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5 votes
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How does the brain project pain on to a particular part of the body?

Short answer Peripheral sensory information is projected unidirectionally to the brain. A sensory strip of the brain contains a topographical representation of the surface of the body that facilitates ...
AliceD's user avatar
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5 votes

Do neurons fire at a faster rate during dreaming?

In REM sleep, the EEG is remarkably similar to that of the awake state (Purves et al., 2001). Although the EEG represents the synchronized activity of many neurons in the cortex, it does give us a ...
AliceD's user avatar
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5 votes

Is it true that stimulants make neurons fire more often, and depressants make them fire less often?

Short answer Generally spoken, yes. Background Excitatory neurotransmitters lower the firing threshold, inhibitory neurotransmitters raise the firing threshold (Fig. 1). For example, glutamate is ...
AliceD's user avatar
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5 votes
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What happens in my retina if I press on my eyeballs?

Short answer Pressure phosphenes are believed to be induced by sensory neurons in the retina downstream from the photoreceptors due to stretch-mediated activation. Background You are referring to ...
AliceD's user avatar
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5 votes

Why our brain can't fool itself to constantly produce dopamine?

Short answer Continuous activation of the reward system leads to habituation and hence a downregulation of the pleasure feelings. Further, a continuous euphoric state is a potentially harmful state, ...
AliceD's user avatar
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5 votes
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Does NMDA-receptor activation depend on neighboring AMPA-receptor activity?

Yes, there most certainly is "local membrane potential". There are two major levels of compartmentalization in dendritic processing. For one, most excitatory synapses occur onto "spines", which have ...
honi's user avatar
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5 votes
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Are there animals with only excitatory neurons?

Not in any well-studied animal; for example, C. elegans certainly has both excitatory and inhibitory neurons. Even in animals with very simple and poorly understood nervous systems (for example, ...
Bryan Krause's user avatar
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5 votes

Myelin and Myelin Sheath

As Wikipedia points out: Myelin is a lipid-rich (fatty) substance formed in the central nervous system (CNS) by glial cells called oligodendrocytes, and in the peripheral nervous system (PNS) by ...
Chris Rogers's user avatar
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5 votes

Is there any justification for viewing neurons as self-interested agents?

The answer to "is there any justification" is pretty much always "yes", but that can be a quite uninteresting "yes" if those justifications are poor. People justify bad ...
Bryan Krause's user avatar
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5 votes
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How can someone enjoy something without dopamine?

It is oversimplifying things that a single compound mediates complex human behavior. To nuance things a bit, there are more neurotransmitters and modulators that mediate feelings of pleasure, as you ...
AliceD's user avatar
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5 votes

Why are there receptors inside neural cells?

Why are they inside if the role of receptors is communication between cells? 'Receptors' are ubiquitous in biology and not just for communication between cells: they carry signals within cells, too. ...
Bryan Krause's user avatar
  • 7,376
4 votes

Can a hyperpolarized neuron fire action potentials?

In principle, no. An action potential is initiated due to the activation of Na+ channels. These are so-called voltage-gated channels, meaning that they sense a depolarization and subsequently open ...
AliceD's user avatar
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