Week 1
Chapter 2: Introducing the brain:
All neurons have basically the same
structure. They consist of a cell body (or
soma), dendrites, and an axon.
Synapse → communication between
neurons via a small gap through chemical
signals (neurotransmitters)
Neurons are organized within the brain to
form white matter and gray matter. Gray matter consists of neuronal cell bodies. White matter
consists of axons and support cells (glia).
→ gray matter includes the basal ganglia, the limbic
system, and the diencephalon
The ventricles are filled with cerebrospinal fluid
(CSF), which does serve some useful functions, as
caring waste metabolites, transfers some
messenger signals, and provides a protective
cushion for the brain
There are three different kinds of white
matter tracts, depending on the nature of
the regions that are connected
,Gyri: the raised surfaces of the cortex
Sulci: the dips or folds of the cortex
The cortex consists of the: neocortex, mesocortex and the allocortex. It also consists of four
lobes: frontal, parietal, temporal and occipital. There are three different ways in which regions of
cerebral cortex may be divided and hence, labeled:
1) Regions divides by the patterns of gyri and sulci
2) Regions divided by cytoarchitecture, in terms of
Brodmann’s areas; divided the cortex up into
approximately 52 areas, based on relative
distribution of cell types across the cortical layer
3) Regions divided by function
The subcortex can be typically divided into a number of
different system with different evolutionary and functional
histories
1) Basal ganglia → involved in regulating motor activity, and programming and termination
of action
a) Disorders can be characterized as hypokinetic or hyperkinetic, including
Parkinson’s and Huntington’s disease
b) Also involved in the learning of rewards, skills, and habits
c) The main structures comprising the basal ganglia are
i) The caudate nucleus
ii) The putamen
iii) The globus pallidus
2) The limbic system → important for relating the
organism to its environment based on current
needs and the present situation, and based on
previous experiences by emotions (everything a
dog does, is probably regulated by the limbic
system)
a) Involved in the detection and expression of emotional responses
b) Amygdala (2 small balls)→ detection of fearful or threatening stimuli
c) Cingulate gyrus → detection of emotional cognitive conflicts
d) Hippocampus → learning memory
e) The mamillary bodies → two round
protrusions that have been traditionally been
implicated in memory
f) Olfactory bulbs → importance of smell and its
influence on mood and memory
,3) The diencephalon → the two main structures:
a) Thalamus
i) Main sensory relay for all senses (except smell)
ii) Projections to almost all parts of the cortex and basal ganglia
iii) Lateral geniculate nucleus → primary visual
iv) Medial geniculate nucleus → primary auditory
b) Hypothalamus
i) Variety of nuclei that are specialized for different functions primarily
concerned with the body. These include body temperature, hunger and
thirst, sexual activity, and regulation of endocrine functions
4) The midbrain and hindbrain
a) Superior colliculus → integrate information from several senses (vision, hearing,
and touch)
b) Inferior colliculus → specialized for auditory processing
c) Substantia nigra → cell loss is associated with the symptoms of parkinson's
syndrome
d) The cerebellum → important for
dexterity and smooth execution of
movement, as well as balance and
coordination
e) The pons → key link between the
cerebellum and the cerebrum. It
receives information from visuals
areas to control eye and body
movements
f) Medulla oblongata → protrudes from
the pons and merges with the spinal
cord. It regulates vital function such
as breathing, swallowing, heart rate,
and the wake-sleep cycle
, Wait but why: Neuralink post
The brain has three membranes around it
underneath the skull:
1) Dura mater → On the outside, a firm,
rugged, waterproof layer. This layer is sensitive to pain, just as skin (headaches)
2) Arachnoid mater→ below dura mater, which is a layer of skin and then an open space
with these stretchy-looking fibers. The fibers stabilize the brain in position, and act as a
shock absorber. This area is filled with spinal fluid, with density similar to water
3) Pia mater → a fine delicate layer of skin that’s fused with the outside of the brain.
Contain blood vessels
The nervous system is divided into two parts:
1) The central nervous system → brain and spinal cord
2) Peripheral nervous system → neurons that radiate outwards from the spinal cord intro
the rest of the body
Interneurons: neurons that communicate with other neurons
Sensory / motor neurons: head down into your spinal cord and make up the peripheral nervous
system
The peripheral nervous system originates from the two strips, motor cortex and somatosensory
cortex
Nerve: a few bundles of axons wrapped together in a little cord
→ ending:
We know the most important parts, but the inbetween parts are still unknown