Transcript nervous system

Introduction to the
nervous System
1
Development of the Nervous
System
Formation of neurons – neurogenesis- largely
prenatal

Majority of cells develop in first 3 months gestation up to 150,000 cells per minute easily disrupted by
chemicals and radiation
Migration pre and post natal


Cells move from where they were formed to their
target area
They move either toward or away from chemicals
released by areas of the brain
Interconnections develop – largely postnatal
Programmed cell death
2
Divisions of the nervous system
Central nervous system - encased in bone


Spinal cord
brain
Peripheral nervous system – everything else

Somatic nervous system – voluntary control
Sensory nerves
Motor nerves

Autonomic nervous system – no conscious control
Sympathetic nervous system – fight or flight response
Parasympathetic nervous system -
3
The spinal cord
4
Function of the spinal cord
White matter – nerve
fibers running to and
from the brain
Gray matter –
neurons and
synapses, mediates
reflexes
Dorsa horn – sensory
Ventral horn - motor
5
The Mammalian Brain
6
Mammal Brains
7
The Human Brain
8
Hindbrain
Medulla – involved with
autonomic system –regulating
breathing and vomiting, etc.
Reticular activating and raphe
system – activates the brain
maintaining arousal or reduces
arousal for sleep
Locus coeruleus – mood
control and alerting response
Cerebellum – coordination of
voluntary movements, eye
saccades, and simple learning
9
Midbrain
Contains centres for the receipt and integration of
several types of sensory information
The superior and inferior colliculi are part of the visual
and auditory systems
The reticular formation is the core of the brainstem
running through the mid-brain, pons and medulla
Some researchers have speculated that the reticular
formation controls approximately 25 specific behaviors,
including sleeping, walking, eating, urination, defecation,
and sexual activity
10
Hindbrain and Midbrain
11
Limbic System
Hypothalamus

Controls eating drinking,
sexual, etc. behaviors
Hippocampus

Formation of new
memories
Septum

Emotion and emotional
memories
Amygdala


Implements aggressive
behavior
Active in fear conditioning
12
Cerebrum
Two hemispheres
Major coordinating centers for from which
sensory information and accompanying
motor actions originate
The surface of the cerebrum is known as
the cerebral cortex
13
Cortex
Composed of grey matter
Has many folds that increase surface area
(called fissures)
Posterior and central areas primarily
concerned with sensory and motor functions
Frontal lobe – inhibition of behaviors,
expression of emotion, availability of rewards
Prefrontal areas




Orbitofrontal – learning reward associations
Prefrontal working memory and thinking
Dorsolateral – maintenance of attentional demands
of a task
Anterior cingulate – mediates attention, inhibition of
dominant behaviors
14
The Cortex
15
Occipital Lobe
Sensory areas associated with vision
Association areas interpret visual
information
16
Temporal Lobe
Sensory areas associated with vision and
hearing
Association areas have been linked to
memory and interpretation of sensory
information
17
Parietal Lobe
Sensory areas associated with touch and
temperature awareness
Association areas have been linked to
emotions and interpreting speech
18