Are neural connections one-way?
Are neural connections one-way?


Yes. Action potentials travel only from dendrites towards axon.


  typically shown in pictures as an electric pulse traveling along a long, thin connective tissue.


What connective tissue? That thin "wire" which carries the action potential is a part of the neural cell body called axon.

Depending on what the axon connects to, there are 6 types of synapses:

"Blausen 0843 SynapseTypes" by BruceBlaus. When using this image in external sources it can be cited as:
Blausen.com staff. "Blausen gallery 2014". Wikiversity Journal of Medicine. DOI:10.15347/wjm/2014.010. ISSN 20018762. - Own work. Licensed under CC BY 3.0 via Wikimedia Commons. 

A synapse is the connection between two structures: the axon of a neuron which "outputs" a signal (chemical or electrical) and the other structure ("input") that can be:


a dendrite or any other specific receptor from a cell
a neural body (can receive both electrical and chemical stimuli) 



  what happens if both neurons fire at the same time on that connection?


In the situation of an axoaxonic synapse (example 2 and even 5 and 6 from the above illustration), the presynaptic neuron can have inhibitory action (nicely explained on michaeldmann.net at Presynaptic inhibition) from where I quote:


  Activity at the axoaxonic synapse partially hypopolarizes the terminal so that, when an action potential comes down the [...] afferent fiber into that terminal, its amplitude is reduced. Because the amount of transmitter substance released by a bouton is proportional to the amplitude of the action potential in it, less transmitter substance is released, resulting in a smaller EPSP and less excitation of the postsynaptic cell [...]




Links:


http://en.wikipedia.org/wiki/Synapse
http://www.getbodysmart.com/ap/nervoussystem/neurophysiology/synapses/introduction/synaptic_contacts/tutorial.html
http://michaeldmann.net/mann13.html