Brain and Nervous System

Anatomy of the Brain: Structure and Function

Neurons: The Basic Unit of Communication

Neurotransmitters and Hormones

Neuroplasticity

Interdisciplinary Approach: Neuroscience

Begins with studying cells of the nervous system

Neurons - up to one billion cells

- inter-connections up to 50,000 per neuron

Glia - outnumber neurons 10:1

- function not incompletely understood

Studying the Nervous System

Clinical observation

Neuropsychology

Studying the Nervous System

Experimental Techniques

Neuroimaging TechniquesUsed to examine structures and functioning of brain

Computerized Tomography (CT):

Magnetic Resonance Imaging (MRI), functional MRI (fMRI):

Neuroimaging techniques, cont’d.

Positron Emission Tomography (PET):

Electroencephalography (EEG):

The Nervous System

Communication throughout the body

Highly organized network

Relays, processes, and integrates information

The Architecture of the Nervous System

Limbic System

Involved in the regulation of motivational and emotional states

Aggression, fear, anxiety, appetite (stress-induced eating)

Kluver-Bucy Syndrome: (Humans)

The Cerebral Cortex

Cortical Brain Structures

3 mm thickness; millions of cells 80% of total brain volume Convoluted (folded) structure increases overall

amount of tissue (total area = 1 sq metre) Divided into 2 hemispheres and 4 paired lobes:

frontal, temporal, occipital, parietal

Lateralization

Two “sides” to the brain: LEFT and RIGHT hemispheres

Contralateral organization: LEFT hemisphere controls actions of RIGHT side of body

Most structures are bilateral

Hemispheres connected through “commissures” – bundled neural fibers

Cerebral Commissures

Tracts that connect the left and right cerebral hemispheres 

Example: Corpus Callosum  

Lateralization - Cerebral Asymmetry

Cortical Control of Sensory and Motor Information

(Sensory and Motor Homunculus)

The Developing Nervous System

Neurogenesis: Differentiation among cells Proliferation of cells; Migration Nearly complete by month 5 of uterine gestation in

humans

Connections among neurons and selective death of neurons: (Pruning/Wiring)

Can continue into adulthood.

The Neuron

Characteristics of the Neuron

Communication within the Neuron

Communication between Neurons

Communication within the Neuron

Distribution of charged particles; ions

Sodium; Potassium

Communication within the Neuron

Action Potential

Momentary change from about -70 mV to +50 mV.

Communication between Neurons

Neurotransmitters and Receptors

Endorphins, NPY, PYY, Urocortin, Substance P.

Neurotransmitter vs Hormone

[Hormones are chemicals released by endocrine

glands into blood circulation]

Some final thoughts on the CNS…..

The Brain is “PLASTIC”