Neural Stem Cells and Connectionism
Let us look at the case of neural stem cell transplantation within the body. Neural cell transplantation in monkeys has shown to have formed connections with other areas of the brain. Moreover, a recent study of neural stem cell transplantation for chronic spinal cord injury revealed increase in neurological performance, suggesting that the neurons did, in fact, connect with the host’s original neurons. Other studies do show that neural stem cells have promise for integrating with neurodegenerative regions; Furthermore, research has shown that neurons do not show adverse effects and increased neurological function in humans that had traumatic brain injury. So in conclusion, yes,neural connections in-vivo appear to increase through the use of stem cells. Note, however, that these connections I refer to are between the implanted stem cells and existing ones, not between already existing stem cells. Although it can be speculated that existing connections are improved through stem cells, this seems unlikely and difficult to justify since there is no reason for implanted stem cells to augment previously existing connections (I have not found any research relating to such a possibility).
Now, let us look at the case in-vitro. This perhaps does not even require research to justify: Yes, neurons tend to form connections when grown in a cell plate.This is because increased confluency (i.e, neural density) forces neural dendrites to contact with each other, yielding new connections. However, these connections by no means represent ‘thought’ or consciousness. Furthermore, neural connections have been shown to connect in a manner that mimics in-vivo connectivity. In fact, this connectivity is what leads to the development of brain organoids (3-D masses of neural stem cells connected together to form tissue), where neurons tend to aggregate in a self-organizing way that resembles ‘mini-brains’, and are often used as models in pathological research.  A mechanism for developing mid-brain organoids containing interconnected neurons via synapses is shown here, again supporting the possibility of neural connection strengthening over time.