Neural and Hormonal Systems

Biology, Behavior, and Mind

• Biological Psychologists: study links between biological (genetic, neural, hormonal) and psychological processes

Research over the past century includes:

• adaptive brain is wired by our experiences

• among the body’s cells and nerve cells that conduct electricity and “talk” to each other by sending chemical messages across a tiny gap that separates them

• specific brain systems serve specific functions

• we integrate info processed in different brain systems to construct our experiences of sights and sounds, meanings and memories, pain and passion

The body creates systems in larger and smaller groups

• example: tiny cells → body organs → body functions → entire body/person’s actions

• these combine to form the study and impact biopsychosocial systems among human behavior

The Power of Plasticity

• Plasticity: the brain’s ability change, especially during childhood, by reorganizing after damage or by building new pathways based on experience

Neural changes occurring in brain are essential to growth and learning, often described using plasticity. This can occur when the brain changes in the practice and dedication of ideas, skills, and consistent interactions with people you spend time with.

Neural Communication

Animals may differ in the complexities of their brains, but their nervous systems are relatively the same to humans and other mammals, which can be used to compare and learn about our own neurons.

What we’ve learned so far includes:

• building blocks of the brain are neurons, or nerve cells

• cell body and branching fibers are part of the structure

• dendrite fibers at the end of the neuron receive and integrate info, which passes the message using the axon fiber

  • remember: dendrites listen, axons speak

• myelin sheath provides a fatty tissue layer that insulates axons and speeds their impulses

• glial cells in the nervous system helps nourish and protect neurons, while playing a role in learning, thinking, and memory

  • ex: worker bees to queen bees are as glial cells are to neurons in the nervous system

• action potential describes the neural impulses occurring in our brains, such as a brief electrical charge that travels down an axon

• reflexes are delayed and take longer to process, depending on type of neurons being activated

• ions are exchanged in a neurons chemical-electric process

• axons surface to selectively permeable areas of the cell, chooses what enters

• resting potential separates the positive and negative charges of the ions entering the neuron cell

• most neural signals are excitatory, like “pushing a neuron’s gas pedal”

• some neural signals are inhibitory, like “pushing a neuron’s brake”

• the threshold is the level of stimulation required to trigger a neural impulse

• strong stimulus trigger more neurons to fire and the frequency of firing to increase

  • this doesn’t affect the action potential’s strength or speed

• a slight lag between neurons is cause by the gap separating them (neurons don’t touch!)

• synapse is the meeting point between two neurons, which carry signals from one to the next

  • dendrites and axons don’t fully touch, also called “protoplasmic kisses”

• neurotransmitters are chemical messengers that cross the synaptic gaps between neurons

• reuptake describes a neurotransmitter’s reabsorption by the sending neuron

Experimental Discoveries of the Brain

The Tools of Discovery: Having our Head Examined

• early discoveries focused on larger regions/generalizations of the brain, as they didn’t have the tools to look further or confirm their theories

• modern day tools are used to detect smaller intricacies, down to electrical pulse of a single neuron

• optogenetics allow researches to observe and control the activity of individual neurons

• MRIs, PETs, and EEGs are forms of brain scans to provide insight into structure, function, and activity of the brain in different settings and tasks

Responses to Damage

• a severed brain and spinal cord neurons, unlike cut skin, usually do not regenerate or connect again

• some brain functions seem preassigned to specific areas

• functions can be reassigned when damage occurs, often thanks to neurogenesis and plasticity

• some neurons are automatically being created, especially in extremely active brain areas

  • ex: 700 new hippocampus neurons are born daily (relates to learning and memory functions)

The Divided Brain

• the brain is split into two hemispheres, the lateralization of left and right brain

• split brain patients often do tasks separately, different parts of their brain control left vs right side

• the brain often runs on autopilot, it acts first and explains itself which is shown through the verbal explanations provided by the left brain

• left hemisphere can make quick, literal interpretations of language and reasoning

• the right hemisphere excels in making inferences, helps us modulate our speech, and orchestrate self awareness and perception