Introduction to Psychology: Biological Psychology

Biological Psychology

  • also known as behavioral neuroscience or physiological psychology
  • Branch of psychology concerned with the linked between biology and behavior
  • Some biological psychologists call themselves behavior neuroscientists, neuropsychologists, behavior geneticists, physiological psychologists, or biopsychologists

Principles

  • Everything psychological is simultaneously biological
  • The nervous system is “plastic” (changed or modeled) especially at early ages of development

Philosophical Roots of Biological Psychology

  • Rene Descartes
    • Father of modern philosophy
    • Discussed the role of the mind and the brain in the control of behavior
    • Reflexes: behaviors that seem to be executed automatically
    • believed that the mind controls the body’s movements, while the sense organs provide information to the mind
  • Pineal Body
    • The brain is composed of hollow chambers filled with pressurized fluids
    • When the mind decides to perform an action, the pineal body tilts (like a joystick), thus causing the fluid to flow onto the specific nerves and inflating the muscles to move
    • Principal seat of the soul and the place in which all our thoughts are formed
    • It is nowadays known that the pineal gland is an endocrine organ, which produces the hormone melatonin in amounts which vary with the time of day
    • But this is a relatively recent discovery long before it was made, physicians and philosophers were already busily speculating about its functions
    • The pineal gland played the important role in Descartes’s account because it was involved in sensation, imagination, memory, and the causation of bodily movements
    • Unfortunately, however, some of Descartes’s basic anatomical and physiological assumptions were totally mistaken, not only by our standards, but also in light of what was already known in his time
  • Luigi Galvani
    • Found out that stimulating specific nerve through electricity made the muscle connected to such nerve
    • Galvani’s work pioneered the field of electrophysiology, the branch of science concerned with electrical phenomena in the body, and Volta’s experiments resulted in his development of the Voltaic pile, an early form of the battery
  • Johannes Muller
    • Demonstrated that there are 5 types of sensory nerves; furthermore, each nerve type, when stimulated results in its own characteristic sensation. Thus, the same stimulus may produce different sensations depending on what nerves of sense were activated
  • Pierre Flourens
    • Was accepted as a pioneer of the modern theory of brain function. According to this theory, the brain acts only as a functional entity although specific functions are controlled by specific parts of the brain
    • Reached this theory using ablation and stimulation methods and many experimental investigations on mammalian species, especially rabbit and pigeons
  • Paul Broca
    • Applied the principle of experimental ablation by studying human brains which were damaged because of stroke
    • **Broca’s Area **has since ranked among the brain’s most closely examined language regions in cognitive psychology. People with Broca’s aphasia are characterized as having suffered damage to the brain’s frontal lobe and tend to speak in short, stilted phrases that often omit short connecting words such as “the” and “and”
  • Gustav Fritsch and Eduard Hitzig
    • Motor cortex
    • First indication that the cortex was electrically excitable
    • First evidence of a topographically organized representation in the brain

Split the Brain: A Case of Disclosure and Brain Function

Why is there electrical activity in the brain? Describe how is it used by neurons?

  • The nervous system operates using an electrochemical process
  • An electrical charge moves through the neuron itself and chemicals are used to transmit information between neurons. Within the neuron, when a signal is strong enough is received by the dendrites, it is transmitted to the soma in the form of an electrical signal and if the signal is strong enough. I may, then, be passed on to the axon and then to the terminal buttons. If the signal reaches the terminal buttons, they are signaled to emit chemicals known as neurotransmitters, which communicate with other neurons across the spaces between the cells (synapses)
    • Cell Body: soma
    • Dendrites: receive messages from other cells or from other neurons
    • Axon: passes messages away from the cell body to other neurons
    • Action Potential: electrical signal traveling down the axon
    • Myelin Sheath: covers the axon of some neurons and helps speed neural impulses
    • Terminal Buttons: form junctions with other cells
  • Neurons in the brain communicate via rapid electrical impulses the allow the brain to coordinate behavior, sensation, thoughts, and emotion
  • Neurons decode information with electrical signals and transmit that information to other neurons by synapses. The action potential is a very important electrical signal (spike) because it typically occurs in less than a second and involves a big voltage change, for a cell, of many tens of millivolts

What happens to the brain during a seizure?

  • Neurons normally communicate by using electrical and chemical signals or messages that cause “depolarization”. But sometimes neurons might send out an abnormal message.
  • If just a single neuron behaves like this and sends out an unusual message, it is unlikely to cause a seizure. But if lots of neurons, from the same part of the brain, send out unusual messages together, then this could cause a seizure to happen.
  • For the messages to cause a seizure:
    • Every neuron must be excited
    • They must be connected to many other neurons within just a few synapses
    • The message must be large enough to cause the other neurons to act in the same way
  • May affect just a part of the brain (partial seizure)
  • Could spread to affect the whole part of the brain (generalized seizure)
  • Epileptic Focus: the part of the brain where the disruption starts

What might cause neurons to behave differently from normal?

  • If neurons are damaged, this might change how they normally work and affect how they send signals.
  • If there are too many or not enough neurotransmitters, this affects how the neurons can communicate, and could cause seizures
  • Some neurons have ion channels which are slower than normal, that is the messages are not “turned off” as quickly as they would normally
  • Some neurons may have different synaptic receptors that receive the neurotransmitters, and this could make it harder for the neuron to stop or “switch off” the message. So the neuron continues to send the message even after it isn’t needed anymore