Welcome to this course
about the cellular mechanisms of brain function.
Brain function governs our every thought and every action.
Activity in our brain allows us 
to perceive the world and learn from our experiences.
So, how does the brain do that?
This course aims for a causal and mechanistic explanation
of brain function, at the level of the brain's irreducible components:
its neurons and synapses.
The neurons are the excitable cells of the brain,
and the synapses are the specializations
where the neurons communicate with each other.
In the same way that Newtonian and quantum mechanics
provide equations for the laws of physics,
here we seek the underlying laws governing neuronal activity:
the biophysics of brain function.
However, in contrast to physics, neuroscience is still a very young field.
It's only just over a hundred years ago
that the neurons of the brain were first described,
and there's much that still remains unknown.
Neuroscience is now undergoing a revolution,
with an ever-increasing speed of discovery
driven by new techniques and exciting hypotheses
that are continuously being developed.
This course will take you through the basic principles
of mammalian brain function,
and try to assemble that knowledge into a coherent and up-to-date description
of how neuronal activity can process sensory information,
leading to subjective percepts and behavioral decisions.
Here, in this introductory video,
I'll give you a brief overview of the course.
The course lasts seven weeks, and every week there'll be five videos,
each lasting 15 to 30 minutes.
At the end of each video, there'll be a short quiz
to help you better understand the subject matter.
If you have further questions or you want to go deeper,
then you should write comments in the online discussion forum,
which I hope will be a lively, fun, and interactive environment.
We'll begin in weeks one to three
with studying the basic principles of how neurons and synapses work.
In weeks four and five, we'll think about how neurons are wired
into networks of excitatory and inhibitory neurons.
And finally, in weeks six and seven,
we'll consider how to study neuronal network function in behaving animals,
and how we can now begin to causally link brain function and behavior.
The brain is essentially an electrical device.
Electricity is not generated by the movement of electrons,
as in an electronic computer,
but rather by the movement of charged atoms: that is, ions.
It's the movement of ions across the cell membrane
that generates the electrical signals in the brain.
These ionic currents flow across the elongated neuronal structures,
and at synapses, these electrical signals
are converted into the release of chemical messages:
so-called neurotransmitters that affect specific target neurons.
After this introductory video, there are four further videos of week one.
We'll discuss the lipid bilayer of the cell membrane
that electrically acts as a capacitor;
and we will also discuss the protein ion channels
that allow transport of speciifc ions across the cell membrane.
The different concentrations of ions inside and outside of cells
and the differential ion permeability of the cell membrane
causes an electrical potential: the so-called membrane potential.
Because neurons have long, elongated processes that act as cables,
these electrical potentials have complex spaciotemporal dynamics.
In week two, we'll learn about nonlinear signal processing inside neurons
generated by so-called voltage-gated ion channels
with complex kinetics of activation and inactivation,
depending upon the membrane potential.
These nonlinear ionic conductances form the basis
of an all-or-none digital signal, the action potential,
which forms an important unit of information in the brain.
The action potential actively propagates down the neuronal cables,
and is therefore useful for transfering information
from one part of the brain to another.
At the end of week two, we'll make a lab excursion
to see how neuronal membrane potential and action potentials
can be measured in vitro in mouse brain slices
using the whole-cell patch clamp recording technique.
A key function of the action potential is to drive synaptic transmission:
the release of a chemical substance, a neurotransmitter,
sending a signal  to other specific neurons.
Synaptic transmission involves a complex cascade of molecular processes
which are strongly influenced by recent patterns of activity,
giving rise to interesting  presynaptic dynamics.
Synaptic transmission is also strongly regulated
by the presence of other chemical substances, termed neuromodulators,
which are present in the extracellular space of the brain.
In the last video of week three, we'll make another lab excursion:
this time, to see how we can image synapses at high resolution
using electron microscopy.
Having got a basic understanding of the components of the brain,
we'll next turn our attention to how the neurons work together
in neuronal networks.
We'll focus on the two most important neurotransmitters in the brain:
the excitatory neurotransmitter glutamate and the inhibitory neurotransmitter GABA.
These are released from different cell types in the brain
which are wired together in highly-specific networks.
In week four of the course, we will study the receptors
that receive the glutamate signals from other neurons,
and we'll discuss the excitatory electrical signals
driven by the activation of the glutamate receptors:
the so-called excitatory post-synaptic potentials.
We'll also study examples of specific neuronal circuits
used for signalling information from the sensory periphery
to higher stations in the brain.
These synaptic circuits are not written in stone;
rather, they can change through a process known as synaptic plasticity.
And these long-lasting, activity-dependent changes in synaptic strength
are thought to underlie learning and memory.
Much of this synaptic plasticity occurs
at the specialized structures called dendritic spines
that we'll study in some detail.
Whereas the neurotransmitter glutamate drives excitation of the neurons,
the neurotransmitter GABA inhibits neurons.
Neuronal networks, therefore, work through a dynamic process
of integrating excitatory  glutamatergic signals
with inhibitory GABAergic signals.
We'll study the synaptic conductances evoked by GABA
and some specific neuronal circuits  in the brain that use GABA.
In addition, we'll introduce the field of neuropharmacology
in the context of benzodiazepines,
which act specifically at GABA receptors
and are widely used as an anxiolytic medication.
Neuropharmacology is of obvious importance
because it provides the simplest means of treating brain disorders.
The purpose of the brain is to govern behavior;
so in order to understand brain function,
we need to correlate and control neuronal activity in living animals
during quantified behavior.
This is an important challenge for modern, integrative neuroscience,
and solving this will provide causal and mechanistic insight
into deep questions about how our brains work.
Breakthroughs in linking neuronal activity to behavior
will also form the foundations necessary for developing rational therapies
to treat the many brain diseases.
Up to this point in the course, 
we will largely have covered principles of neuroscience
derived from reduced, in vitro preparations.
In order to investigate mammalian brain function during behavior
in mechanistic detail,
we need to make invasive, in vivo measurements and manipulations.
The overall organization of the mammalian brain
is similar across a wide range of species, 
and currently, substantial effort goes into understanding the mouse brain.
What we learn from studying the mouse brain
will in many cases likely be directly analogous
to what happens in the human brain.
We'll describe techniques for optical imaging of the mouse brain,
resolving signals at millisecond temporal resolution
and with cellular and subcellular spatial resolution.
Electrophysiological measurements can also be made in behaving mice,
allowing action potential firing and membrane potential dynamics
to be studied during quantified behavior.
In order to gain causal insight,
these methods for correlating neuronal activity with behavior
must now be complemented by manipulations of neuronal activity.
Over the last few years, the development of optogenetics
is providing tools that allow neuroscientists
to control highly-specific neuronal activity
with millisecond precision.
We are now in a position
to investigate the causal, neuronal mechanisms underlying behavior.
In the final week of the course, we'll begin by considering behavior
as a result of movements driven by specific motor neurons.
Sensory input provides important information for guiding motor control,
and so the simplest behaviors 
can be regarded as sensorimotor interactions.
We'll also learn that sensory perception is an active process
whereby we make movements to gain specific information:
like moving our eyes to look at an interesting object,
or touching a surface to feel its shape and texture.
Sensory perception is also an active process
from an internal, computational perspective
whereby the neurons in our brains generate sensory percepts
derived from our past experiences and current expectations.
We'll also study aspects of reward-based learning,
in which the brain tries to organize behavior to maximize reward.
Finally, we'll discuss  how the cellular mechanisms
of some brain diseases are beginning to be understood,
giving hope for future treatments.
So, in this course, you'll see  that the unitary elements of the brain,
the neurons and synapses, are beginning to be understood in biophysical detail.
We already have quite a good quantitative description
of membrane potential, action potentials, and synaptic transmission.
Neuroscientists have also made good progress
in delineating the synaptic connectivity of specific neuronal cell types.
We're thus learning a lot about the rules underlying the wiring diagram
of the mammalian brain.
The next major challenge for modern neuroscience
is now to causally link neuronal activity to behavior.
This requires in vivo measurements and manipulations
to correlate and perturb brain function during behavior.
Fortunately, enormous progress has been made,
and many neuroscientists think that we'll have a deep understanding
of how the basic operating principles of the mammalian brain govern behavior
within the next 50 years, and hopefully within our lifetimes.