The Biology of the Mind

Chapter 2

Neuron

A nerve cell, or a neuron, consists of many different parts.

Pretty Neurons

Pretty neurons

Neurons

How do neurons work?

• How does the signal get from one end of the neuron to the other?– Sometimes traveling several feet almost

instantaneously!

• How does the signal get passed from one neuron to another neuron?

Action PotentialA neural impulse. A

brief electrical charge that travels down an

axon and is generated by the movement of positively charged atoms in and out of

channels in the axon’s membrane.

Synapse

Reuptake

This process stops the

neurotransmitter action.

How Neurotransmitters Influence Us

Serotonin pathways are involved with mood regulation.

From Mapping the Mind, Rita Carter, © 1989 University of California Press

Dopamine Pathways

Dopamine pathways are involved with

diseases such as schizophrenia and

Parkinson’s disease.

From Mapping the Mind, Rita Carter, © 1989 University of California Press

Neurotransmitters

The Endocrine System: of Chemicals and Glands

• Chemical communication network that sends messages throughout the body via the bloodstream– Hormones– Pituitary gland

Feldman

How are Hormones Regulated? Example:

Regulation of Sex

hormones

Hormones of interest

– Vasopressin – helps maintain proper concentrations in our bodies

– Oxytocin – labor and lactation, Love– Testosterone

• http://www.thisamericanlife.org/radio-archives/episode/220/testosterone/

– Estrogens

The Nervous System

The Brain: Older Brain Structures

The Brainstem is the oldest part of the brain, beginning where the spinal cord swells and enters the skull. It is responsible for automatic survival

functions.

The Limbic System associated with

emotions such as fear, aggression

and drives for food and sex. It includes the hippocampus,

amygdala, and hypothalamus.

The Brain: The Limbic System

The Brain: Structure of the Cortex

More intelligent animals have increased “uncommitted” or association areas of the

cortex.

Association Areas

Methods for studying the Brain

Lesioning

Hubel (1990)

Electroencephalogram (EEG)measured by electrodes placed on the

scalp.A

J Photo/ P

hoto Researchers, Inc.

PET Scan

PET (positron emission tomography)

Scan is a visual display of brain

activity that detects a radioactive form of

glucose.

Courtesy of N

ational Brookhaven N

ational Laboratories

MRI ScanMRI (magnetic

resonance imaging)

Both photos from Daniel Weinberger, M.D., CBDB, NIMH

James Salzano/ Salzano Photo Lucy Reading/ Lucy Illustrations

Neuroplasticity and the Brain

• Neuroplasticity– The brain continually reorganizing itself

• Neurogenesis – New neurons created in certain areas of the

brain during adulthood

Right-Left Differences in the Intact Brain

People with intact brains also show left-right hemispheric differences in mental

abilities.What is the difference in the function

between the left and right hemisphere of the Cortex?

Splitting the BrainA procedure in which the two hemispheres of the brain are isolated by cutting the connecting fibers

(mainly those of the corpus callosum) between them.

Corpus Callosum

Ma

rtin M

. Ro

the

r

Courtesy of T

erence William

s, University of Iow

a

Split Brain Patients

With the corpus callosum severed, objects (apple) presented in the right visual field can be named.

Objects (pencil) in the left visual field cannot.

Divided Consciousness