PSY 2210 Exam 2

What do you know about neuroscience's explanations of why we sleep and why we dream?

We sleep to rest our skeletal muscles, decreas metabolism, perform cellular maintenance in neurons, reorganize synapses, strengthen memory. Originally, it was to conserve energy. -We dream to cope with the events of the day. To either deal with trauma and issues that we faced during the day, or to interpret our "good" events of the day. Basically, dreaming is used as a coping mechanism and interpretation of the day.

What do you know about collateral sprouting and denervation supersensitivity?

Collateral Sprouts are new branches formed by other non-damaged axons that attach to vacant receptors. Cells that have lost their source of innervation release neurotophins that induce axons to form collateral sprouts. They can be helpful, neutral, or harmful. -Denervation Supersensitivity is the heightened sensitivity to a neurotransmitter after the destruction of an incoming axon. This can cause consequences such as chronic pain.

What do you know about the genetics of dominant versus recessive traits? What about intermediate expression of genes?

-Dominant Genes are the genes that are expressed compared to Recessive Genes. If a Dominant Gene is present with a Recessive Gene also present, then the Dominant Gene will be expressed. Same with two Dominant Genes. The only time a Recessive Gene is expressed is if the parents are both carriers for a Recessive Gene or if both parents are solely Recessive. Intermediate Gene Expression is a combination of Dominant and Recessive Gene Expression. One gene is not fully expressed over the other, like flower petal colors.

What do you know about endogenous cycles, biological clocks, and the brain mechanisms that are involved in them?

-Endogenous Cycles, also Circannual Rhythms, are internal mechanisms that operate on an annual or yearly cycle, such as squirrels storing food for winter. Circadian Rhythms are a biological internal mechanism that operates on a slightly longer than 24-hour cycle, resetting them can be necessary sometimes. Changes in our environment are associated with endogenous biological clocks and circadian rhythms. -The Suprachiasmatic Nucleus (SCN), genes that produce certain proteins (PER and TIM), and melatonin levels are involved.

How does evolution work? What were Lamarck's ideas about evolution? What evolutionary explanations for altruism have been proposed?

-Evolution is the long process of different kinds of organisms being developed and diversified from earlier forms during the Earth's existence, often arising from natural selection and provide an advantage to survival (not always). -Lamarck hypothesized that giraffes grew their necks to reach the leaves in taller trees. As the trees grew, so did the giraffe's neck. His version of evolution was much quicker than reality. -Altruism is the idea that individuals help those that will return the favor. Further, building a reputation for helpfulness only works if others are willing to cooperate with you. Organisms behave altruistically when its behavior benefits others, and not itself, in hope for reciprocity in the future.

What is heritability and how is it measured? What do you know about PKU?

-Heritability is a statistic used in the fields of breeding and genetics that estimates the degree of variation in a phenotypic trait in a population that is due to genetic variation between individuals in that population. PKU is phenylketonuria and it is an error of the metabolism that results in decreased metabolism of the amino acid phenylalanine.

What do you know about CNS development in the embryo? What about development in the fetus? What happens to the brain during an infant's first year?

-It begins to develop around 2 weeks old. The ectoderm thickens, and fold to form a neural tube surrounding a fluid filled cavity. It undergoes the embryonic stage: neural tube folding becoming the central canal and the four ventricles. Differentiates to the mid, hind, and forebrain. The rest of the neural tube becomes the spinal cord. The fetal stage: the CNS becomes increasingly complex. Around 9 months old the child should achieve object permanence. And weigh around 1000 grams.

How do neurons grow and what happens as we mature to the wealth of neurons we are born with? What is known about axon path finding? What do you know about Roger Sperry's research that built on the work of Paul Weiss? What is neural Darwinism?

-Neural Growth Factor (NGF) is a type of protein released by muscles that promotes the survival and growth of axons. Neurotropins are chemicals that promote neural survival and activity of neurons. Proliferation occurs, then differentiation forms the supportive structures of the neuron. Most of the neurons that are made a kept, however if a neuron is deemed unnecessary or unneeded, they will be pruned away. -Axon pathfinding is when a neuronal axon is looking for specific connections to another neuron. Weiss grafted a third leg on a salamander, and it gained control of the leg, thus concluding neuronal branching to the new limb. Sperry cut axons of the optic nerve to tectum and rotated a newt's eye but axons returned to their original site. -Neural Dwarfism: Selection Process of Neural Connections; We form more initial neural connections than we need

Can you name and describe the processes that neurons undergo as they develop?

-Proliferation: Production of new cells/neurons in the brain (early in life) -Migration: Movement of newly formed neurons and glia to their eventual locations -Differentiation: Forming of the axon and dendrites -Myelination: Glia produce fatty sheath that covers some axons -Synaptogenesis: Formation of synapses between neurons

What do you know about the human karyotype, especially the sex chromosomes? What are sex-linked and sex-limited traits?

A human karyotype is a visual representation of the 23 pairs of chromosomes that make up the human genetic code. For the 23rd pair, the sex chromosomes, the X is large and if a Y is present it is small. However, if another X is present, being XX, then they will be closer in size than the XY combination. -Sex Linked Traits are traits that are often determined by the sex chromosome. Typically, they only affect the males (XY). Sex Limited Traits are autosomal, not sex linked, meaning they are not determinate solely on the sex chromosomes.

What are the stages of sleep and what happens to the brain and the body in these stages?

Alpha Waves occur when one is relaxed. Stage One occurs when someone first falls asleep (Theta Waves), Stage Two has sleep spindles and K-Complexes, Stage Three and Four constitute slow wave sleep (Delta Waves)

Can you differentiate phenotype and genotype?

Genotype is genes. Phenotype is physical features.

What is the nature of threats to the developing brain?

Homeobox genes regulate the expression of other genes and control the start of anatomical development. A mutation on one gene can lead to many defects. During early development, the brain is vulnerable to malnutrition, radiation, toxic chemicals, and infections. These can cause significant impairment and developmental problems. FAS (Fetal Alcohol Syndrome is an example)

What factors promote sleep and what do you know about sleep abnormalities/disorders?

Melatonin is the neurotransmitter that causes the tired feeling and promotes sleep. Sleep Disorders include Insomnia, Sleep Apnea, Narcolepsy, Sexomnia, Periodic Limb Movement Disorder, REM Behavior Disorder, Night Terrors, etc.

What distinguishes REM from NREM sleep and what happens in the brain during REM sleep that keeps us from acting out our dreams?

REM Sleep, aka Paradoxical Sleep, is a deep sleep in some ways, but light sleep in other ways. REM is Rapid Eye Movement during sleep. Beta Waves occur during REM. Our brain shuts down motor function for our limbs so that we do not actively act out our dreams. NREM is Non-REM Sleep.

Can the brain generate new neurons? How and where?

The Brain can regenerate olfactory receptors to replace the dying ones. Stem cells differentiate in the hippocampus. They form through stem cells and differentiation. Cerebral Cortex neurons do not form any, or no, new neurons.

What role does the environment play for good or ill in nervous system development? How does experience "fine-tune" the brain? Can you explain, for example, focal hand dystonia?

The Brain can reorganize itself in response to experience. Axons and dendrites continue to modify their structure and connections throughout life. Dendrites continue to grow new spines. The loss or gain of dendritic spines indicates new connections, which relates to learning. -Focal Hand Dystonia is caused by the overuse of the thenar and hypothenar muscles (the hand muscles). It is often called writers or musicians cramp.

What do you know about the types of injuries the brain can sustain? What factors influence recovery?

The Brain can sustain strokes, concussions, closed/open head traumas, hemorrhages, etc. Recovery is dependent on the type of cerebral accident that happened. If it is severe like a hemorrhage, then the recovery will take longer, and the person usually will not fully recover. If it is more mild like a concussion, then the person is able to recover quicker and their neural plasticity can aid in this recovery if any neurons or its components are damaged.

What do you know about brain organization? Can you explain what happens in early onset blindness and the phantom limb phenomenon?

The brain is able to reorganize itself through a process called plasticity. Neural Plasticity means that the brain, if injured, is able to rewire its circuitry to be able to perform tasks and functions that may have been lost due to the injury. Early Onset Blindness Individuals still use their Occipital Lobe for sense purposes, but it is different from a sighted person. The Phantom Limb Phenomenon is when a person with an amputated limb, typically, can feel sensations in the area where the limb previously occupied.