Biology and Behavior

Chapter 2

Part II

A Walk Through the Brain

• The brain stem.• The cerebellum.• The thalamus.• The hypothalamus and the pituitary gland.• The amygdala.• The hippocampus.• The cerebrum and lobes of the cerebral

cortex..

Mapping the Brain Web-site

• http://www.howstuffworks.com/brain.htm/printable

The Brain Stem

• Pons – involved in sleeping, waking and

dreaming.

• Medulla – responsible for certain

automatic functions such as breathing and heart rate.

• Reticular activating system (or formation)– arouses cortex and screens

incoming information.

The Cerebellum

• Regulates movement and balance.

• Involved in remembering simple skills and acquired reflexes.

• Plays a part in analyzing sensory information, solving problems and understanding words

The Thalamus

• Relays sensory messages to the cerebral cortex.• Includes all sensory messages except those from

olfactory bulb.

Hypothalamus and Pituitary Gland• Involved in emotions and

drives vital to survival including fear, hunger, thirst, and reproduction.

• Also regulates autonomic nervous system.

• The pituitary gland is a small endocrine gland which releases hormones and regulates other endocrine glands.

Pituitary Gland

The Amygdala• Responsible for arousal

and regulation of emotion and the initial emotional response to sensory information.

• Plays important role in mediating anxiety and depression.

The Hippocampus• Responsible for the

storage of new information in memory.

• Compares information with what the brain has come to expect about the world.

• “Gateway to memory” because it enables us to navigate through the environment.

The Cerebrum

• Largest brain structure.• Consists of upper part of brain and divided

into two cerebral hemispheres which are connected by the corpus callosum.

• In charge of most sensory, motor and cognitive processes.

• Surrounded by cerebral cortex, a collection of several thin layers of cells (gray matter).

Lobes of the Cerebral Cortex• Occipital lobes (Latin-in back of head)

– Visual cortex.

• Parietal lobes (Latin-pertaining to walls)– Somatosensory cortex.

• Temporal lobes (pertaining to the temples)– Memory, perception, emotion and auditory cortex.– Left lobe, Wernicke’s area.

• Frontal lobes – Emotion, planning, creative thinking and motor

cortex.– Left lobe, Broca’s area.

The Corpus Callosum

• Millions of myelinated axons connecting the brain’s hemispheres.

• Provides a pathway for communication between the hemispheres.

• If surgically severed for treatment of epilepsy, hemispheres cannot communicate directly.

©1999 Prentice Hall

Cerebral Hemispheres

Are There “His” and “Hers” Brains?

• After analyzing 49 studies of sex differences in brain anatomy, researchers found small differences between the two groups and larger differences within groups.

• There does appear to be sex differences in lateralization of language. Males show left hemisphere activation only. Females, left and right.

• There also appears to be differences in amounts of gray matter. Females have more.

©1999 Prentice Hall

Genes and Behavioral Genetics

• Genes– The segments of DNA that are located on the

chromosomes and are the basic units for the transmission of all hereditary traits

• Chromosomes– Rod-shaped structures in the nuclei of body cells

that contain all the genes and carry all the hereditary information

• Zygote– A single cell formed from the union of 23

chromosomes from the male’s sperm and 23 chromosomes from the female’s egg

©1999 Prentice Hall

Genes and Behavioral Genetics

• Sex-linked inheritance– Involves the genes on the X and Y chromosomes– In females, the harmful gene is offset by the gene

that is not harmful – In males, if the single X chromosome carries a

harmful gene, there is no offsetting gene on the Y chromosome because it is very small and carries only the genes needed to create the male body type

Electroencephalogram (EEG)

• A recording of neural activity detected by electrodes.

Magnetic Resonance Imaging (MRI)

• Method for studying body and brain tissue.

• Magnetic fields align certain ions and compounds

• When field is removed, these molecules release energy as radio waves

• Computer calculates tissue density from radio waves.

• Provides clear, 3D images.

Positron Emission Tomography (PET)

• A method for analyzing biochemical activity in the brain, using injections of a glucose-like substance containing a radioactive element.

• Active areas have increased blood flow.

• Sensors detect radioactivity.

• Different tasks show distinct activity patterns.

The Origin or the CAT Scan

The Lesson of Einstein’s Brain

• Like any muscle, a life time of thinking can bulk up your brain as well!