Optimal synaptic assignment for locomotory behavior in C. elegans (Rakowski & Karbowski 2017)

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"The detailed knowledge of C. elegans connectome for 3 decades has not contributed dramatically to our understanding of worm’s behavior. One of main reasons for this situation has been the lack of data on the type of synaptic signaling between particular neurons in the worm’s connectome. The aim of this study was to determine synaptic polarities for each connection in a small pre-motor circuit controlling locomotion. Even in this compact network of just 7 neurons the space of all possible patterns of connection types (excitation vs. inhibition) is huge. To deal effectively with this combinatorial problem we devised a novel and relatively fast technique based on genetic algorithms and large-scale parallel computations, which we combined with detailed neurophysiological modeling of interneuron dynamics and compared the theory to the available behavioral data. As a result of these massive computations, we found that the optimal connectivity pattern that matches the best locomotory data is the one in which all interneuron connections are inhibitory, even those terminating on motor neurons. ..."
1 . Rakowski F, Karbowski J (2017) Optimal synaptic signaling connectome for locomotory behavior in Caenorhabditis elegans: Design minimizing energy cost. PLoS Comput Biol 13:e1005834 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Synapse;
Brain Region(s)/Organism:
Cell Type(s):
Gap Junctions:
Transmitter(s): Acetylcholine;
Simulation Environment: Java (web link to model); Mathematica (web link to model);
Model Concept(s): Invertebrate;
Implementer(s): Rakowski, Franciszek ;
Search NeuronDB for information about:  Acetylcholine;
(located via links below)
# Copyright (c) 2006, 2008 Junio C Hamano
# The "pre-rebase" hook is run just before "git rebase" starts doing
# its job, and can prevent the command from running by exiting with
# non-zero status.
# The hook is called with the following parameters:
# $1 -- the upstream the series was forked from.
# $2 -- the branch being rebased (or empty when rebasing the current branch).
# This sample shows how to prevent topic branches that are already
# merged to 'next' branch from getting rebased, because allowing it
# would result in rebasing already published history.

if test "$#" = 2
	topic=`git symbolic-ref HEAD` ||
	exit 0 ;# we do not interrupt rebasing detached HEAD

case "$topic" in
	exit 0 ;# we do not interrupt others.

# Now we are dealing with a topic branch being rebased
# on top of master.  Is it OK to rebase it?

# Does the topic really exist?
git show-ref -q "$topic" || {
	echo >&2 "No such branch $topic"
	exit 1

# Is topic fully merged to master?
not_in_master=`git rev-list --pretty=oneline ^master "$topic"`
if test -z "$not_in_master"
	echo >&2 "$topic is fully merged to master; better remove it."
	exit 1 ;# we could allow it, but there is no point.

# Is topic ever merged to next?  If so you should not be rebasing it.
only_next_1=`git rev-list ^master "^$topic" ${publish} | sort`
only_next_2=`git rev-list ^master           ${publish} | sort`
if test "$only_next_1" = "$only_next_2"
	not_in_topic=`git rev-list "^$topic" master`
	if test -z "$not_in_topic"
		echo >&2 "$topic is already up-to-date with master"
		exit 1 ;# we could allow it, but there is no point.
		exit 0
	not_in_next=`git rev-list --pretty=oneline ^${publish} "$topic"`
	/usr/bin/perl -e '
		my $topic = $ARGV[0];
		my $msg = "* $topic has commits already merged to public branch:\n";
		my (%not_in_next) = map {
			/^([0-9a-f]+) /;
			($1 => 1);
		} split(/\n/, $ARGV[1]);
		for my $elem (map {
				/^([0-9a-f]+) (.*)$/;
				[$1 => $2];
			} split(/\n/, $ARGV[2])) {
			if (!exists $not_in_next{$elem->[0]}) {
				if ($msg) {
					print STDERR $msg;
					undef $msg;
				print STDERR " $elem->[1]\n";
	' "$topic" "$not_in_next" "$not_in_master"
	exit 1

exit 0


This sample hook safeguards topic branches that have been
published from being rewound.

The workflow assumed here is:

 * Once a topic branch forks from "master", "master" is never
   merged into it again (either directly or indirectly).

 * Once a topic branch is fully cooked and merged into "master",
   it is deleted.  If you need to build on top of it to correct
   earlier mistakes, a new topic branch is created by forking at
   the tip of the "master".  This is not strictly necessary, but
   it makes it easier to keep your history simple.

 * Whenever you need to test or publish your changes to topic
   branches, merge them into "next" branch.

The script, being an example, hardcodes the publish branch name
to be "next", but it is trivial to make it configurable via
$GIT_DIR/config mechanism.

With this workflow, you would want to know:

(1) ... if a topic branch has ever been merged to "next".  Young
    topic branches can have stupid mistakes you would rather
    clean up before publishing, and things that have not been
    merged into other branches can be easily rebased without
    affecting other people.  But once it is published, you would
    not want to rewind it.

(2) ... if a topic branch has been fully merged to "master".
    Then you can delete it.  More importantly, you should not
    build on top of it -- other people may already want to
    change things related to the topic as patches against your
    "master", so if you need further changes, it is better to
    fork the topic (perhaps with the same name) afresh from the
    tip of "master".

Let's look at this example:

		   o---o---o---o---o---o---o---o---o---o "next"
		  /       /           /           /
		 /   a---a---b A     /           /
		/   /               /           /
	       /   /   c---c---c---c B         /
	      /   /   /             \         /
	     /   /   /   b---b C     \       /
	    /   /   /   /             \     /
    ---o---o---o---o---o---o---o---o---o---o---o "master"

A, B and C are topic branches.

 * A has one fix since it was merged up to "next".

 * B has finished.  It has been fully merged up to "master" and "next",
   and is ready to be deleted.

 * C has not merged to "next" at all.

We would want to allow C to be rebased, refuse A, and encourage
B to be deleted.

To compute (1):

	git rev-list ^master ^topic next
	git rev-list ^master        next

	if these match, topic has not merged in next at all.

To compute (2):

	git rev-list master..topic

	if this is empty, it is fully merged to "master".

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