12
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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 ...
- 1,855
8
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How do neurons decide how to alter their output signals?
This will be a long post. FYI.
To my knowledge, there is no evidence for back propagation in the brain. If you're interested specifically in that topic, Geoffrey Hinton (Dept. of CS @ UofT) has ...
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8
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Does adult neurogenesis occur only in the olfactory bulb and the hippocampus?
You are right that active adult neurogenesis is generally considered to be restricted to the dentate gyrus of the hippocampus, and the subventricular zone of the lateral ventricles. The latter ...
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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 ...
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8
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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 ...
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7
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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 ...
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7
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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 ...
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7
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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 ...
- 20.5k
7
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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, ...
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7
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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., ...
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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 ...
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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 ...
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6
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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).
...
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6
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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 ...
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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 ...
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5
votes
Accepted
Can Transcranial Magnetic Stimulation (TMS), or a magnets cap make you smarter?
Short answer
A cap of magnets, or state-of-the-art TMS protocols, will not make you smarter.
Background
First off, TMS uses bursts of magnetic stimulation in the order of milliseconds (Rothkegel et ...
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5
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How do neurons decide how to alter their output signals?
Short answer
Neurons can increase or decrease the amplitude of their response. A neuron's response strength can be regulated by adjustment of the cell-surface expression of excitatory receptors.
...
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5
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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
...
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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 ...
- 306
5
votes
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What are 'gap junctions' (electrical synapses) for?
Gap junctions can couple cells directly electrically. Cell types electrically coupled via gap junctions include neurons, the pancreatic islets of Langerhans (Andreu et al, 1997) and cardiac cells (Fig....
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5
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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
...
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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 ...
- 850
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, ...
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5
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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 ...
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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 ...
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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 ...
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5
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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 ...
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5
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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, ...
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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 ...
- 1,855
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, ...
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Only top scored, non community-wiki answers of a minimum length are eligible