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 Techniques Used 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”