Behavioral Neuroscience: Exam 3 Flashcards
Neural Development
An ongoing process ; the nervous system is plastic.
The Case of Genie
At the age of 13, Genie was discovered in a dark room tied to a chair. She weighed 62 pounds and was unable to chew solid food. She could not speak because she was never introduced to speech. She was beaten, starved, restrained, kept in a dark room, and denied normal human interactions.
Even with special care and training after her rescue, her behavior never become normal.
Zygote
Ovum + Sperm
Developing Neurons Accomplish Things in Five Phases (5 Phases of Development) Essay Question
- Induction of the neural plate
- Neural proliferation
- Migration and aggregation
- Axon growth and synapse formation
- Neuron death and synapse rearrangement
Induction of the Neural Plate
Starting off with a collection of cells. The new zygote is plate shaped. The collection of cells will start to fold on itself and form a valley (neural groove). This process begins shaping the nervous system (neural tube).
A patch of tissue on the dorsal surface of the embryo becomes the neural plate. Neural plate cells are often referred to as embryonic stem cells. Development is induced by chemical signals from the mesoderm. The neural plate is visible 3 weeks after conception.
Neural Proliferation
The mass growing of neural stem cells.
Migration and Aggregation
The moving of neural stem cells throughout the body. Migrating cells are immature, lacking axons and dendrites. The clotting of cells together and then they begin to specialize (aggregation).
Axon Growth and Synapse Formation
Once cells are specialized they seek out other compatible cells and make a connection, and then build a synapse. These then become functional neural circuits and additional specialization.
Neuron Death and Synapse Rearrangement
After the first several years of life, the brain starts pruning away neurons that did not make a connection or form a functional synapse. So the brain kills off these cells through starvation or the will be genetically triggered to kill themselves. This allows the remaining neurons to become stronger, and they form stronger synaptic connections (rearrangement).
Three layers of embryonic cells:
Ectoderm
Mesoderm
Endoderm
Endoderm
(Innermost Layer) Will become all of our guts and organs.
Mesoderm
(Middle Layer) Will become our muscles. The “organizer”.
Ectoderm
(Outermost Layer) Will become all of our peripheral nerves and all of our central nervous system.
Embryonic Stem Cells
- AKA Neural Plate Cells
- Have unlimited capacity for self renewal
- Can become any kind of mature cell
Totipotent
The earliest embryonic stem cells have the ability to become any type of body cell.
Multipotent
With development, neural plate cells are limited to becoming one of the range of mature nervous system cells.
Two Types of Neural Tube Migration
- Radial Migration (moving out)
- Tangential Migration (moving up)
Two Methods of Migration
- Somal - an extension develops that leads migration, cell body follows
- Glial - mediated migration (the cell moves along a radial glial network)
*Most cells engage in both types of migration
Neural Crest
- Formed from neural tube cells
- Develops into the cells of the peripheral nervous system
- Cells migrate long distances
Cell-Adhesion Molecules (CAMs)
- Aid both migration and aggregation
- CAMs recognize and adhere to molecules
Pioneer Growth Cone
The first to travel a route, interact with guidance molecules.
Fasiculation
The tendency of developing axons to grow along the paths established by preceding axons.
Synapse Formation
- High levels of cholesterol are needed which is supplied by astrocytes
- Depends on the presence of glial cells
Neurotrophins
Promote growth and survival. They guide axons and stimulate synaptogenesis (the formation of additional synapses).
Necrosis
Passive cell death.
Apoptosis
Active cell death.
Postnatal Growth
Is a consequence of:
- Synaptogenesis
- Myelination
- Increased dendritic branches
*Overproduction of synapses may underlie the greater plasticity of the young brain
Development of the Prefrontal Cortex
- Believed to underlie age-related changes in cognitive function
- No single theory explains the function of this area
- Prefrontal cortex plays a role in working memory, planning and carrying out sequences of actions, and inhibiting inappropriate/ dangerous responses.
Permissive Experiences
Experiences that are necessary for information in genetic programs to be manifested. Give the brain permission to grow a specific structure. Must happen during the critical period of development,
Instructive Experiences
Those that contribute to the direction of development.
Nuerogenesis
Growth of new neurons. Adult neural stem cells are created in the epedymal layer lining in ventricles and adjacent tissues.
*Enriched environments can promote neurogenesis
Tinnitus
Ringing in the ears. Produces major reorganization of primary auditory cortex.
Autism
Three core symptoms:
- Reduced ability to interpret emotions
- Reduced capacity for social interaction
- Preoccupation with a single subject or activity
- Autism is heterogenous (the level of brain damage and dysfunction varies)
- Often considered a spectrum disorder
William’s Syndrome
- Mental retardation, and an uneven pattern of abilities and disabilities
- Opposite of autism
- Profound impairments in spatial cognition
- Mutation on chromosome 7
H.M Case Study
H.M. was a man suffering from severe epilepsy. He could no longer live independently or manage his own self-care. He had his temporal lobes removed in 1953. His seizures were dramatically reduced, but so was his long-term memory. H.M is unable to form most types of new long-term memories, but his short-term memory is still intact.
-Mild retrograde amnesia and severe anterograde amnesia.
Retrograde Amnesia
- Backward acting
- Unable to remember the past
Anterograde Amnesia
- Forward acting
- Unable to form new memories
- You can remember things from the past
Digit Span
H.M. can repeat digits provide the time between learning and recall is within the duration of short-term memory
Block-Tapping Memory-Span Test
This test demonstrated that H.M.s amnesia was global - not limited to one sensory modality
3 Major Contributions of H.M.s Case
- Medial temporal lobes are involved in memory
- Short term memory, remote memory and long term memory and distinctly separate
- Memory may exist but not be recalled (explicit vs. implicit)
Explicit
-Conscious memories
Implicit
-Unconscious memories, as when H.M. shows the benefits of prior experience
Medial Temporal Lobe Amnesia
-These people may have trouble imagining future events
R.B. Case Study
- R.B. suffered damage to just one part of the hippocampus and developed amnesia
- R.B.s case suggest that hippocampal damage alone can produce amnesia
- H.M.s damage and amnesia was more severe than R.B.s