Neurophysiology chapter
Central vs Peripheral Nervous System
I. Hierarchy of Brain organization
a. Based on its embryonic development, the brain can be divided into 3 regions the
forebrain, the midbrain, and the hindbrain
II. Central (Brain)
a. Forebrain (foreword most portion of brain) contains the cerebral cortex, the
limbic system, the basal ganglia, and the dienephalon
i. Cerebrum or cerebral cortex
1. Is arbitrarily divided into lobes named after the bones that cover
them: the frontal, parietal, temporal, and occipital
a. Frontal
i. Associated with reasoning, planning, parts
of speech, movement, emotions, and
problem solving
ii. Major Components
1. motor cortex (movement)
2. prefrontal cortex (executive functions)
3. Broca’s area (speech)
b. Parietal
i. Associated with movement, orientation in
3-D space (spacial) recognition, perception
of stimuli,
ii. Major components
1. somatosensory complex (pain, touch,
pressure sensation) - located next to motor
cortex of frontal lobe
c. Temporal
i. Associated with perception and recognition of
auditory stimuli, memory, and speech
ii. We often focus on the hippocampus here. This
part of the brain is important for learning and
memory...specifically converting short term to
more perminant memory and for recalling spatial
relationships
iii. Area of the brain first affected by Alzheimer’s
disease
, d. Occipital
i. Associated with visual processing
2. The medial aspect of the cerebrum is organized into concentric
bands that are referred to as the limbic system - often referred to
as the emotional brain
a.Includes
i. Cingulate
ii. Parahippocampal gyri
iii. Amyglada
iv. Thalamus (also considered part of the
diencephalon)
v. Hypothalamus (also considered part of
diencephalon)
vi. Hippocampus
b. Stimulation of the limbic system can lead to feelings of
dread, high anxiety, or exquisite pleasure. It also can result
in violent behaviors, including attack, defense, or
explosive/emotional speech.
ii. Diencephalon
a. Thalamus
i. The thalamus plays a role in relaying critical
information regarding motor activities to and from
selected areas of motor cortex
ii. 2 neuronal pathways are significant: one is the
pathway from the cerebral cortex to the pons and
cerebellum and then by the way of the thalamus
back to the Motor cortex, the second is a feedback
circuit that travels from the cortex to the basal
ganglia, then to the thalamus, and from the
thalamus back to the cortex.
iii. See discussion on motor control
b. Hypothalamus (master regulator of homeostatic control)
i. Controls the tropic hormones that control the
anterior pituitary gland
ii. Produces oxytocin and ADH
iii. Regulation of water balance (osmoreceptors)
iv. Regulation of appetite (target of hormones
ghrelin and leptin)
v. Regulates body temperature
, vi. Participates in the regulation of ANS vii.
Regulates reproductive function via GnRH
iii. Basal ganglia
1. Lies lateral to the thalamus and consists of
a. Caudate nucleus
b. Putamen
c. Globus pallitus (Internal and External)
d. Note that the Striatum = caudate + putamen
2. Supply axial and proximal unlearned and learned postures and
movements, which have gracefulness to upper motor neuron
controlled movements.
a. Intact basal ganglia allow for fine tuned movements that
we often take for granted including but not limited to
i. Arm swinging during walking
ii. Turning while walking
3. See motor lecture for details on integration
a. Disorders of the basal ganglia that will be discussed in
5226 include: Parkinson’s disease and Huntington’s disease
b. Hindbrain
i. Cerebellum (part of hind brain)
1. Coordinates movement, important for
posture and balance
2. Participates in small aspects of learning ii.
Pons, Medulla Oblongata)
1. Contains all fibers passing between the spinal cord, forebrain and
cerebellum
2. Contains integrating neurons/centers for respiratory and
cardiovascular systems
3. Contains cranial nerves III through XII
c. Midbrain
i. Part of brainstem (with Pons and Medulla Oblongata - portions of the
hindbrain)
ii. Midbrain also consists of the tectum and tegmentum
III. Central (Spinal Cord)
a. The spinal cord is divided into two areas: central gray matter, which contains
nerve cell bodies and dendrites; and white matter, which surrounds the gray
matter and contains myelinated axons organized into ascending or descending
tracts
i. The axons of the afferent and efferent neurons form the spinal nerves
IV. Peripheral Nervous System (PNS)