Biological and Psychology

Why are psychologists concerned about human biology?

  • The nervous system and body chemistry play a vital role in our behavior and mental processes
  • Many of the important questions that psychologists ask are related to biology and the brain
  • Questions
  • Are the two halves of the brain specialized to perform different functions?
  • How do mood altering drugs work?
  • What happens inside the body when you feel a strong emotion?
  • Are some mental disorders the result of chemical imbalances in the brain?

Biological Psychology - Branch of psychology concerned with the links between biology and behavior

Some biological psychologists call themselves behavioral neuroscientists, neuropsychologists, behavior geneticists, physiological psychologists, or biopsychologists

Key: Understanding Neurons and the Nervous system

The Nervous System

  • the body’s speedy, electrochemical communication system
  • consists of all the nerve cells of the peripheral and central nervous systems
  • Billions of interconnected cells

The Nervous System: Divisions

  • Central nervous system (CNS) - Brain and spinal cord
  • Peripheral nervous system (PNS)
  • Somatic nervous system - Sensory nerves and muscular activity
  • Autonomic nervous system – internal organs
  • Sympathetic nervous system – arouses
  • Parasympathetic nervous system – calms

The Nervous System: Pathways

  • Interneurons – neurons of the spinal cord and brain which process information
  • Afferent Nerves (sensory nerves) - Carry information to the spinal cord and brain
  • Efferent Nerves (motor nerves) - Carry information to the muscles

Neurons are individual cells in the nervous system that receive, integrate, and transmit information.

  • Approximately 100 billion neurons and 10 trillion connections
  • Speeds up to 330 miles per hour
  • Glia Cells: Provide support and nutrition
  • Over 200 types of neurons and glia cells

Common Features of Neurons

  • Dendrites
  • Cell body or soma
  • Axon
  • Myelin sheath
  • Terminal buttons

Synapse - a junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. This tiny gap is called the synaptic gap or cleft.

Neurotransmitters – chemicals that transmit information from one neuron to another.

  • Stored in small sacs within the terminal buttons
  • Nerve impulse triggers their release
  • Over 50 have been identified
  • Major ones are described in the text

Drugs and Neurotransmitters

  • Agonist – mimics or enhances NT effects
  • Antagonist – blocks effects of NT

Brain and its Structures

Brain: 3 Main divisions

  • Hindbrain – vital functions – medulla, pons, and cerebellum
  • Midbrain – sensory functions –reticular activating system
  • Forebrain – emotion, complex thought – thalamus, hypothalamus, limbic system, cerebrum, cerebral cortex

Hindbrain- Most primitive part of the brain – basic life sustaining functions

  • Brain Stem - Alertness, breathing, heart rate, blood pressure
  • Medulla – control breathing, regulate reflexes
  • Cerebellum – movement, motor coordination
  • Pons – governs sleep and arousal

Midbrain

Relay between hindbrain and forebrain

Integrating sensory info.

Reticular Formation - Regulates arousal, attention, sleep/wakefulness, pain perception

Forebrain - Largest and most complex regions of the brain

(Thalamus, hypothalamus, limbic system, cerebrum, or cerebral cortex)

Thalamus - Relay station for much sensory information

Hypothalamus - Eating, drinking, sexual behaviors

It directs several maintenance activities like eating, drinking, body temperature, and control of emotions.

It helps govern the endocrine system via the pituitary gland.

Limbic System – memory, motivation and emotions

  • Amygdala - Emotional awareness and expression
  • Hippocampus - Formation and storage of memories

Damage to the Hippocampus – The case of Clive Wearing

Forebrain: Cerebrum

Largest and most complex part of the brain

The cerebral cortex is the convoluted outer layer of the cerebrum

Cerebral Cortex

  • Occipital Lobe – Vision
  • Temporal Lobe – Hearing, language processing, memory
  • Frontal Lobe – Intelligence, personality, voluntary muscles
  • Parietal Lobe - Spatial location, attention, motor control

Functions of the Cortex

  • The Motor Cortex is the area at the rear of the frontal lobes that control voluntary movements.
  • The Sensory Cortex (parietal cortex) receives information from skin surface and sense organs.

Association Cortex - Region of the cortex in which the highest intellectual functions occur

75% of the cortex

Damage does not lead to specific loss of function

e.g., Phineas Gage Video

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

Cerebral Hemispheres

The cerebral cortex is divided into 2 hemispheres (left and right) connected by the corpus callosum.

Research has shown the some lateralization of the hemispheres exist

Lateralization is the specialization of one the hemispheres to handle a particular function

The left brain control the right side of the body and the right brain controls the left side of the body

Left hemisphere – verbal processing: language, speech, reading, writing

Right hemisphere – nonverbal processing: spatial, musical, visual recognition

Handedness

90% of world’s population is right handed

In 95% of right-handers and about 62% of left-handers, the left hemisphere handles most of the language functions (Hellige, 1990)Including: speaking, writing, reading, and understanding the spoken word

Paul Broca in 1861 noticed that damage to the left hemisphere led to aphasia

Aphasia is an impairment of language, usually caused by left hemisphere damage either to Broca’s area (impaired speaking) or to Wernicke’s area (impaired understanding).

Damage to the right brain often had an effect of stopping spatial recognition of faces and objects

Right Hemisphere - Generally considered to be the hemisphere more adept at visual spatial abilities and at interpreting nonverbal behavior.

Specializations not as evident in young children. Why?

The brain is sculpted by our genes but also by our experiences.

Plasticity refers to the brain’s ability to modify itself after some type of injury or illness.

Split-Brain Research

Splitting the Brain -A procedure in which the two hemispheres of the brain are isolated by cutting the connecting fibers (mainly those of the corpus callosum) between them.

Research by Roger Sperry and Michael Gazzaniga

Non-Split Brains - People with intact brains also show left-right hemispheric differences in mental abilities.

A number of brain scan studies show normal individuals engage their right brain when completing a perceptual task and their left brain when carrying out a linguistic task.