21

There is a huge body of literature on axon growth cone guidance which will give you some insights into how the biology works. Unfortunately, incorporating it all into a model is probably going to make it unwieldy unless your express purpose is to model the physiology, which doesn't seem like the case. Here are some references: Hong K, Nishiyama M. (2010)...


9

Bach-y-Rita's Tactile Vision Substitution System (TVSS) project was initiated in 1963 and he has since been regarded as the founding father of sensory substitution. The concept of sensory substitution refers to the process of obtaining information about the world from a functional sensory system (e.g. touch) that would normally be obtained from a lost ...


7

Short answer Yes, continuous exposure to white noise affects neural responses in the auditory system. First, it can alter the tonotopic map in the auditory cortex. Second, it can lead to reduced responsiveness of the auditory thalamus. Background Note: this answer is based on animal experiments using extreme conditions, namely a continuous noise ...


7

Sadly (or should I be happy that Google is this awesome? Not to mention the rate of scientific progress!), all I really had to do to come up with an answer was perform a Google search for "learning transcranial magnetic stimulation". The first hit, a ScienceDaily page (Ruhr-University Bochum, 2011) page, lists some journal references (Mix, Benali, Eysel, &...


7

For the dentate gyrus, which is probably more closely analogous to a feedforward hidden layer in a memory network, here are some answers: Axon and dendrite connectivity is essentially local and can probably be assumed to be initially random within that local region. That is, a neuron integrating into the DG at the midpoint (along the long hippocampal axis) ...


7

Although LTP might be necessary for brain plasticity, I would doubt that it is also sufficient. There is quite a lot of literature about homeostatic plasticity (for a review, see Turrigiano & Nelson, 2004) and synaptic scaling (for another review, see Turrigiano, 2008) which seem to be necessary to keep LTP working in the long run. References ...


7

Another reason for reduced plasticity in adults is that learning something different in the presence of an existing knowledge structure is more difficult than learning from a "blank slate". In a sense, you get interference from the known language (for example). One person who has developed this argument computationally is Jay McClelland in the context of ...


6

Interesting question! I performed a fairly extensive search in Google Scholar and Scopus using various keyword searches, including, but not limited to "color blindness and plasticity", "color blind and brain", "dichromates brain", and "monochromates brain". Strikingly, I found nothing. The reason is aptly explained by Solomon & Rosa, 2014 and I quote ...


6

The learning rule you describe (i.e. the change of synaptic weights from source neuron to target neuron depending on the temporal difference between source and target activity) is often referred to as 'classical' or 'standard' STDP (spike-timing dependent plasticity) and is focused on connections between excitatory cells. However, this simple form of ...


5

One great example of such plasticity is the ability of early-blind people to utilize their V1 area to read Braille: Functional relevance of cross-modal plasticity in blind humans (Cohen et al., 1997) Excerpt from the abstract: We conclude that blindness from an early age can cause the visual cortex to be recruited to a role in somatosensory processing....


5

Yes, the visual cortex is plastic, even in adults: We measured adaptation in the responses of populations of cat V1 neurons to stimulus ensembles with markedly different statistics of stimulus orientation. We found that adaptation served two homeostatic goals. First, it maintained equality in the time-averaged responses across the population. ...


4

Assuming you're getting at a related idea to your other recent question (Does a more ergonomic and user friendly interface/device make the human brain work less?), I wouldn't worry about user friendliness causing mental atrophy by precluding the need for thought. Thought continues well beyond matters of control to matters of application and optimization. (E....


4

In adult mouse cortex, synaptic spines can last anywhere from days to months. I'm not sure that any such work has been done on human Broca's area, but keep in mind that many synapses are experience dependent. One study found that fear conditioning and fear extinction lead, respectively, to synapse formation and elimination. So the lifetime of a synapse ...


4

Short answer Subcortical structures can definitely show neuroplasticity in adults. Most likely, all brain structures can show plastic changes to some degree. Background The question is rather broad, as there are many subcortical structures and neuroplasticity is age-dependent. I will therefore restrict my answer to three examples I dug up from the ...


4

Short answer The question is kind of broad, and I decided to give four notable examples from credible sources of long-term potentiation of inhibitory responses (iLTP) below. Upregulation of postsynaptic GABAA and GABAB currents are the predominant effectors responsible for iLTP. The mechanism through which these effects are initiated are, however, variable ...


4

The best explanation for STDP that I've ever seen is Nicky Case's Neurotic Neurons. In this Explorable Explanation, I think you'll find that your misunderstanding lies in the fact that both the pre-synaptic (Neuron A) and the post-synaptic neuron (Neuron B) exist in a network of other neurons. They are not only connected to each other. You are correct in ...


3

Homoestatic plasticity can be used with spike-dependent plasticity given they have two different goals and aren't applied uniformly across neural population. To support this argument, I'm going to use a computation model taken from "Simultaneous unsupervised and supervised learning of cognitive functions in biologically plausible spiking neural networks" by ...


3

Probably not. STDP has mostly been demonstrated in excitatory glutamatergic neurons in the hippocampus. Considering all the other types of cells in the brain (dopaminergic, serotonergic, inhibitory, those located in cortical areas with closed plasticity windows those in the brain stem), it's erroneous to assume they all implement STDP like rules. That said, ...


3

I read recently in the book "meet your happy chemicals" that the hormones of puberty are neurochemicals that cause your neurons to connect and myelinate more easily. I will presume that you're referring to brain-derived neurotrophic factor (BDNF) which is involved in neurogenesis and neuroplasticity. If this is true have any studies been done to see if ...


3

Chris gave an excellent answer for visual-to-tactile sensory substitution devices. I will not argue about the extent to which sensory substitution is successful, but the most widespread sensory substitution system for the blind is nowadays The vOICe, a class of visual-to-auditory sensory substitution devices that is available globally. Its Android version ...


3

The time required to learn Braille may vary depending on factors such as age, partial/full and early/late blindness and individual differences (see here), but what has come out of studies such as this is that visual deprivation appears to speed up Braille learning. In the study I cite, all subjects received the same degree of training, but individuals who ...


3

I can't make comments yet, so in the following I will assume that by 'STDP synapse' you mean the model of a synapse using the STDP rule. The scenario that you are describing is a triplet experiment with a PRE-POST-PRE protocol and to answer your question: Yes, in this case the STDP rule predicts both, weakening and strengthening of the same synapse and ...


3

There is some cool evidence (e.g., Canlon et al. 1988) that low level noise exposure can actually protect you against high level noise exposure. That said, I am not sure that one should constantly expose themselves to low level sounds in the hope that it will protect them from high level sounds. Melamed et al. (1996) found that long term exposure to moderate ...


3

The concept of mental rotation was introduced by Shepard & Metzler (1971). The 3D assemblages of cubes were part of their original experiment. Vandenburg and Kuse (1978) later developed a paper-and-pencil test based on this prior experiment, named the Vandenberg and Kuse’s Mental Rotation Test (VMRT). The study which Bavelier most likely refers to is ...


2

Consider that elimination of such a phenomena is not ideal. It's been proposed that actual neuronal networks exist under the tension of synchronous decoupling. http://www.sciencedirect.com/science/article/pii/S0896627308001281 To answer your question though, you probably should consider that reciprocal connections might not be between two individual ...


2

The truth is, we don't fully know. There are likely a number of factors. One of them seems to be the Brain Derived Neurotrophic Factor (BDNF). This molecule seems to be involved with maintaining and encouraging neuron growth. In Rats with a transgenically accelerated rise in BDNF levels, the critical period began earlier, and finished earlier as well (Huang ...


2

Synapses likely change their strengths based on a form of spike-timing-dependent plasticity. Is this true for all types of synapses in all parts of the human brain? No, not all. For example, there is frequency-dependent-plasticity, where the firing frequency of the pre-synaptic cell will change the synaptic strength. In Nikolaev, et. al. (2013), frequencies ...


2

The key concept is that STDP is synapse specific, whereas homeostatic plasticity is more global. (As an aside, it is incorrect to say that STDP strengthens connections. STDP strengthens connections with pre-before-post spiking relationships, but weakens connections with post-before-pre spiking relationships. You man be thinking of Hebbian plasticity. The ...


2

They're mentioning biological plausibility, because they think biological constraints are important for intelligent systems. Also, biologically constrained systems could be easily applied to understanding the brain. Whether biological plausibility is important or not to developing intelligent systems and understanding the brain is a matter of debate. On one ...


2

Short answer Neural plasticity is a broad term. While it has long been recognized, the fact that the adult brain is plastic even at the gross structural level has taken a long time to become widely accepted. Background There are a few things that play a role here. First and foremost, neural plasticity is a term encompassing many different processes. ...


Only top voted, non community-wiki answers of a minimum length are eligible