I am going to try to answer this question using Reductionism and breaking down what a “synapse” is:So, in the human brain there are two primary types of “synapses”:

- Chemical Synapses: the most common of those found in the human brain, have a miniscule gap (called the “synaptic cleft”) between the pre- and post-synaptic neurons. Amongst this gap, chemicals that are produced in the soma of the cell, called Neurotransmitters are released by way of exocytosis ( a fancy word for membranous sacks releasing) into this small gap between neurons, and some are received (by way of receptors) into the post-synaptic cell, of which this process can either decrease or increase the potential (disparity between positive and negative charge amongst the inside and outside of the cell) and influence any further electrical, action potentials (the “firing” of the cell). Furthermore, the electrical current that caused the neurotransmitters to be released in the pre-synaptic cell, is released outside of the cell. There are a plethora of neurotransmitters and a nerve cell only makes/diffuses a specific neurotransmitter, already implicating a great diversity of neurons…which we will delve into later in this answer…

- Electrical Synapses: less common than chemical synapses, and have ion channels that connect the pre- and post- synaptic cells (i.e. there is a continuity between the two cells). Electrical transmissions are extremely rapid and typically bi-directional. The process of which can be shown below, and involves the transmission of an electrical current via “gap junction” channels that are highly conductive and low-resistant to electricity. Furthermore, in the post-synaptic cell features non-gated channels by which some of the electrical current will escape, reducing the electrical potential within the cell.

(a) Electrical Synapse                                   (b) Chemical Synapse

[1]

Now onto the true answer to the question, what is the purpose of these dang things?

Perhaps the most notable reason I could think of for the purpose of this is that of the purpose of sustainability and efficiency in the process of chemical neuro-transmission. The chemical synapse requires more processes than that of an electrical synapse, ( binding of neurotransmitters to vesicles, releasing of neurotransmitters into synaptic cleft, diffuse across cleft, potentially recycling through process of reuptake, etc… i.e: more processes than the simpler electrical synapse)…

Now, imagine a electrical current going through a small pre-synaptic cell, it reaches the synapse and “sees” (bare with me on the lack of technicality) a large post-synaptic cell, how is the subsequent, smaller electrical current going to achieve the threshold and initiate an action potential? Through chemical diffusion of thousands of neurotransmitters diffusing across this small synaptic cleft, of which permit amplification of the synaptic response, enabling a smaller pre-synaptic cell to trigger an action potential in a potentially, much larger post-synaptic cell. This further hints at the fact that there is such a immense diversity of neurons… that a synapse can efficiently and functionally connect different shaped, sized, etc. neurons and have neurotransmitters serve as the liaisons (in transmitting information) between the two different shaped, sized, neurons further hints at its purpose, especially as brains (cerebral cortices, specifically) have augmented in complexity over thousands and thousands of years.

Essentially, a synapse provides the most biologically efficient, robust, versatile (synapses can be modified) mechanism for information to be transmitted chemically and electrically in the brain…

Other reasons for which there is a synaptic gap would include ([2]):

- For chemical synapses, the synaptic gap ensures a unidirectional flow of electrical impulses.

- Permits a ‘refractory period’ of which the process of action potentials is bounded by a upper limit due to limit on neurotransmitter resourcers.. This ensues in sensory adaptation, e.g: you are not constantly stimulated because your shorts are touching your skin…

- Permits impulses to be distributed across multiple post-synaptic neurons and vice versa, multiple impulses can converge at a synapse…

- Further permit spatial summation (many pre-synaptic neurons’ impulses converge on a singular post-synaptic neuron reaching its threshold and firing an action potential) and temporal summation (a rapidly firing, single, pre-synaptic  neuron causes a post-synaptic neuron to fire an action potential) … ensuing in the grading of neural responses (i,e.: too “low” or “infrequent”, not important => don’t transmit).

[1] http://kin450-neurophysiology.wi…
[2] http://www.biologymad.com/nervou…

Short answer: Your brain and the neural activity occurring within it is constantly changing, therefore the answer is “yes.”

Longer Answer:

When you exercise and close your eyes, you will lose a great sense of balance, as vision is crucial for proper balance and posture. However, despite your eyes being closed, your Visual Cortex will still be active, perhaps not as active as before, but active nonetheless, as you will be visualizing and creating some semblance of your surroundings based on visual memories. Also, the visual system is highly connected to other regions of the brain that are responsible for balance and sensory-motor coordination, as will be discussed further in this answer.

On the other hand, neural activity will most likely increase in the other areas responsible for sensory-motor coordination such as the semicircular canals that comprise your vestibular sense which can best be described in this paper called “Balanced Vision: How the Visual and Vestibular Systems Interact:”[2]

“Sometimes called the “balance system,” the vestibular system is located in the inner ear. It is the first fully myelinated sensorimotor system of the human body, and is fully functional at birth, because the mother’s movements during pregnancy stimulate vestibular development in the fetus.

The job of the vestibular system is to sense changes in motion. It is not a motion detector, but rather more of an accelerometer of sorts. It senses both linear and rotational acceleration/deceleration and gravity. It lets us know our position with gravity and whether or not we are moving. It registers linear motion through the utricles (mostly horizontal), and saccules (mostly vertical), which together make up organs called otoliths. Registration of rotary motion is through the six semicircular canals.

Stimulation of the otoliths releases serotonin producing calmness, relaxation and lowered tone. Stimulation of the semicircular canals releases adrenaline producing excitation, arousal and increased tone.”

and in areas of muscular proprioception and your kinesthetic sense. Kinesthetic sense can best be clarified in this article [4]:

[The Kinesthetic sense is] the sense that tells a home-run  hitter that the ball will go out of the park, because he hit the ball  just right & he knows before the crowd does that the ball is on the  way to the bleachers. The proprioceptors in his muscles as he swings the  bat send information to his brain, which puts together all the sensory  input and formulates based on past experience what feels right. Someone  like Sadaharu Oh, the Japanese baseball player who holds the all-time  world record of 868 home runs, would have an excellent sense of what it  feels like to hit a home run.  Like kinesthetic sense, proprioception  describes how much we know about where we are in space and where all of  our parts are in relationship to each other.

Our  kinesthetic sense helps us move with greater precision, avoid injuries,  and be fully present in the moment. This awareness assists us in healing  by enabling us to both consciously & unconsciously direct our  energy and healing activities like fluid and chemical exchanges more  effectively to an injured area. All sorts of factors will influence  human proprioception. The neural pathways in the brain give us an almost  unconscious sense of the right sequence of muscle contractions that  will cause our foot to take a step. Microscopic sensory receptors  throughout our bodies send information. Our mind sorts through and  processes this information in a complex way that science is only  beginning to understand fully. One thing is clear – greater body  awareness leads to improved function and better overall health.

The  neural pathways of kinesthetic sense become more ingrained through  repetition. It can be a challenging process to overcome habits or  tendencies ingrained in movement patterns. One movement pattern will  feel more “normal” or “right” because it is customary… With practice and with time movement training  helps develop greater awareness.”

While your vision has been deemed the most “significant contributor to balance”[1], without it, it would be logical that neural activity would still occur in the Visual Cortex (for the aforementioned reasons), but perhaps not at such copious metabolic rates, and neural activity would continue (if not, augment) in other areas responsible for sensory-motor coordination, particularly the vestibular sense and proprioception and kinesthetic networks of the brain.

References:
[1] http://en.wikipedia.org/wiki/Vis…
[2] http://www.google.com/url?sa=t&r…
[3] http://en.wikipedia.org/wiki/Ves…