Behavioral Neuroscience Exam 3 Review

What is a cladogram?

A diagram showing evolutionary relationships between organisms based on shared characteristics and common ancestors.

What does a branch point in a cladogram represent?

A moment in evolution where one group split into two different lineages.

What is the significance of the proximity of two species on a cladogram?

The closer two species are, the more recently they shared a common ancestor and the more similar they tend to be.

What is a nerve net?

A loose network of neurons spread throughout the body, found in simple organisms like jellyfish, lacking a central brain.

What is a segmented nervous system?

A system where neurons are organized into repeating units along the body, allowing for coordinated movement.

What are ganglia?

Clusters of neurons that act as mini processing centers within a nervous system.

What are nerve trunks?

Long bundles of neurons that connect different parts of the body to facilitate communication.

What is the primary advantage of a centralized nervous system with a brain?

It allows for advanced processing, decision-making, learning, and complex behavior.

Why is DNA similarity between humans and chimpanzees not the only factor in their differences?

Differences in gene expression, regulation, and the timing of development lead to significant phenotypic variations despite similar DNA sequences.

What is the role of the ASPM gene?

It influences cortical size in the brain.

What is the role of the FOXP2 gene?

It is associated with language ability.

What is the difference between genotype and phenotype?

Genotype refers to the genetic code itself, while phenotype refers to the observable traits of an organism.

What is a silent mutation?

A change in the DNA sequence that does not result in a change to the protein produced, often having no noticeable effect on the organism.

Why are silent mutations considered neutral?

Because they do not increase or decrease an organism's chances of survival or reproduction.

What is the central idea of Darwin's principles of evolution?

Organisms produce more offspring than can survive, and those with advantageous traits are more likely to reproduce and pass those traits to the next generation.

What creates competition for survival according to Darwin?

The fact that organisms produce more offspring than the environment can support.

What is the source of natural variation among individuals?

Sexual reproduction.

What acts as the selective force in evolution?

The environment, which favors individuals with traits that increase survival and reproduction.

How does evolution lead to gradual changes in a population?

By favoring individuals with inheritable, advantageous traits, which become more common in the population over generations.

What does it mean that humans 'built on top of' earlier nervous systems?

Humans retain basic neural structures seen in simpler organisms while adding more complex layers.

What is the primary mechanism for the difference in brain structure between humans and other primates?

Differences in gene expression during development, such as prolonged brain development and increased cortical growth.

Why do silent mutations persist in a population?

Because they are neutral and not subject to strong selection pressure.

What is the definition of a codon in the context of mutations?

A DNA sequence that codes for a specific amino acid; multiple codons can code for the same amino acid, allowing for silent mutations.

What is the relationship between genetic differences and phenotypic differences?

Small genetic differences can lead to large phenotypic differences, and conversely, some species with larger genetic differences may appear very similar.

What is the primary function of nerve trunks in complex organisms?

To connect different parts of the body for better communication and organized control.

How long have humans and chimpanzees/bonobos been evolving separately?

Approximately 2 million years.

Is evolution goal-directed or progressive?

No, evolution is not goal-directed; it selects traits that improve reproductive success in a specific environment.

Why does sickle cell anemia persist in some populations?

It provides resistance to malaria, which increases survival rates in environments where malaria is prevalent.

How did Darwin's principles change the understanding of the brain?

They established that the brain, like physical traits, is a product of evolution shaped by natural selection rather than a fixed or uniquely human structure.

What is the relationship between environmental pressure and brain structure?

Species evolve specific brain structures and abilities to support the behaviors required for survival in their unique ecological niche.

What is directional selection?

A type of selection where one extreme version of a trait is favored, causing the population average to shift in that direction over time.

What is stabilizing selection?

A type of selection that favors the average or intermediate form of a trait and selects against extreme variations, reducing population variance.

What is disruptive selection?

A type of selection that favors individuals at both extremes of a trait while selecting against the middle, which can increase variation and lead to new species.

What does it mean that brain evolution involved 'elaboration'?

It means existing brain structures became more complex over time rather than entirely new structures being added.

What role did diet play in the evolution of the human brain?

The shift to high-calorie diets, such as meat, provided the necessary energy to support the metabolically expensive brain.

What is the radiator hypothesis?

The theory that adaptations in blood flow helped dissipate heat from the brain, allowing it to grow larger without overheating.

What is neoteny?

The retention of juvenile characteristics into adulthood, which in humans allows for an extended period of brain development and increased plasticity.

What is encephalization?

A measure of how large an animal's brain is compared to what would be expected for its body size.

Does brain size directly determine intelligence within a species?

No, factors such as brain organization, neuron density, cortical folding, and synaptic complexity are more important than raw size.

Why do humans have a high level of encephalization?

Humans have brains that are disproportionately large relative to their body size, supporting advanced cognitive abilities.

What is the primary benefit of an extended childhood in humans?

It allows for more time for experience-dependent changes, increasing the brain's plasticity and ability to learn.

How does social complexity influence brain evolution?

Living in large, complex groups favors individuals with better communication, memory, and problem-solving skills, driving the development of larger, more complex brains.

What biological changes occurred in the human brain during evolution?

There were increases in neuron number, cortical size, and connectivity, particularly in the neocortex.

What is the significance of cortical folding in the brain?

It is a factor that contributes to cognitive ability by allowing for more surface area and complexity within the skull.

How does natural selection affect traits in a population?

Individuals with advantageous traits are more likely to reproduce, causing those traits to become more common over generations.

What is the relationship between spatial memory and brain anatomy?

Animals that rely heavily on spatial memory often possess larger hippocampi.

What is the relationship between social interaction and brain anatomy?

Species that engage in complex social interactions tend to have more developed cortical regions.

What does 'behavioral flexibility' refer to in human evolution?

The ability to adapt behavior to different environmental challenges, which was enhanced by the expansion of the cortex.

Why is the neocortex important in human evolution?

It is the area where increased connectivity and size led to greater cognitive flexibility and problem-solving abilities.

How does the brain's organization affect its performance?

A smaller but more efficiently connected brain can outperform a larger but less organized one.

What is the role of environmental challenges in evolution?

They act as selective pressures that favor individuals who can adapt behaviorally, such as through migration or climate adaptation.

What is the primary driver of trait distribution changes in a population?

Genetic selection, which is dictated by how traits affect an organism's survival and reproductive success.

What is neoteny in the context of human brain development?

A longer childhood period that allows for more experience-dependent brain changes and increased plasticity.

How does neoteny affect human adaptability?

By keeping the brain in an immature and flexible state for longer, it allows humans to adapt more effectively to their environment.

What is the most significant anatomical difference between human and ape brains?

The size and expansion of the neocortex, particularly in the frontal and parietal lobes.

What is gyrification?

The degree of cortical folding (gyri and sulci) which increases the surface area of the cortex without significantly increasing skull size.

What is the function of the prefrontal cortex in humans?

It is associated with executive functions, impulse control, and social behavior.

What does the phrase 'elaboration rather than addition' mean regarding brain evolution?

It describes how higher brain regions, like the cerebral cortex, take over functions previously controlled by lower regions as the brain becomes more complex.

How did climate change influence human brain evolution?

Moving from stable forests to unpredictable savannas required flexible behavior and advanced cognitive abilities to navigate changing conditions.

Why was the shift to a calorie-dense diet (like meat) important for brain evolution?

The brain is an energy-demanding organ; higher-energy nutrition provided the fuel necessary for the brain to grow larger and more complex.

How did social complexity drive brain evolution?

Living in large groups required understanding hierarchies, cooperation, and communication, which selected for increased memory, emotional regulation, and cortex development.

What cellular differences exist between human and ape neurons?

Human neurons have more complex dendritic branching, allowing for more synaptic connections and sophisticated information processing.

How does cultural transmission contribute to human intelligence?

It allows knowledge to accumulate across generations, creating a feedback loop where better tools and culture select for even more advanced brains.

What is the primary role of NMDA receptor function in brain development?

It enhances synaptic plasticity, which is associated with the prolonged development period in humans.

Why is the human brain considered highly encephalized?

Because human brains are much larger than what would be predicted based on body size alone.

What is the benefit of increased connectivity between brain regions?

It allows different parts of the brain to communicate more efficiently, supporting complex cognitive functions.

What role does tool use play in brain evolution?

It requires planning and foresight, which stimulated the development of brain structures associated with higher-order cognitive functions.

What is the result of the 'cumulative culture' unique to humans?

It allows humans to build upon the knowledge of previous generations, continuously increasing the complexity of human society and intelligence.

How does the neocortex support higher-order functions?

It facilitates reasoning, planning, decision-making, and language.

Is brain size the only factor determining intelligence?

No, intelligence is also determined by brain organization, connectivity, functional specialization, and environmental pressures.

What physiological adaptation helps the human brain manage metabolic heat?

Increased blood flow through the skull, which acts as a radiator to carry heat away from brain tissue.

What does 'plasticity' refer to in the brain?

The brain's ability to form and reorganize connections in response to experience.

How does social intelligence relate to brain structure?

The need to function in complex social groups selected for more developed brain structures, particularly the cortex.

What is the main advantage of having more folds in the cortex?

It increases the surface area of the cortex, allowing for more neurons and more complex processing power.

What is the relationship between brain development and learning?

Extended brain development (neoteny) increases the window of plasticity, allowing humans to acquire complex skills like language and culture.

Why is the human brain considered 'specialized'?

It is highly interconnected and organized to prioritize higher cognitive functions like abstract thinking and social cooperation.

Why is the 'five senses' model considered an oversimplification in neuroscience?

It is a philosophical concept rather than a biological one; the brain processes many distinct sensory inputs using specialized receptors, pathways, and cortical areas rather than just five categories.

What are the four submodalities of somatosensation?

Mechanoreception (touch and pressure), thermoreception (temperature), nociception (pain), and proprioception (body position and movement).

What is the function of mechanoreceptors?

They respond to pressure, stretch, and vibration in the skin to allow for the detection of texture and physical contact.

What is the function of thermoreceptors?

They respond specifically to heat or cold to help the body maintain homeostasis.

What is the function of nociceptors?

They detect potentially damaging stimuli, triggering protective responses and pain perception.

What is the function of proprioception?

It relies on receptors in muscles and joints to inform the brain about limb position and movement, which is essential for coordination.

What two major sensory systems are processed by the inner ear?

The auditory system (hearing) and the vestibular system (balance and spatial orientation).

What is the role of the vestibular system?

It detects head movement and position, including rotational movements via semicircular canals and linear acceleration/gravity via otolith organs, to maintain balance and posture.

What is the primary difference between sensory receptors and neurotransmitter receptors?

Sensory receptors detect external physical or environmental stimuli (transduction), while neurotransmitter receptors detect internal chemical signals released by other neurons at synapses.

What is sensory salience?

The degree to which a stimulus is important or attention-grabbing to the brain, prioritized based on biological or behavioral relevance rather than just physical intensity.

What is the Doctrine of Specific Nerve Energies?

The principle that the brain interprets sensory signals based on which specific neural pathway is activated, rather than the nature of the stimulus itself.

Do sensory receptors always fire action potentials?

No; they typically produce a graded electrical change called a receptor potential first.

What is proprioception?

The sense of body position and movement.

What is equilibrioception?

The sense of balance.

What is interoception?

The sense of internal body states, such as hunger or heart rate.

What process converts physical stimuli into electrical signals in sensory receptors?

Transduction.

Why does pressure on the eye cause a person to 'see stars'?

According to the Doctrine of Specific Nerve Energies, activating the visual pathway is interpreted by the brain as light, regardless of the actual stimulus.

What determines sensory salience beyond physical intensity?

Context and biological or behavioral relevance.

How does the brain organize sensory information?

Functionally, based on the type of stimulus and the specific processing pathway used.

What structures in the inner ear detect rotational head movements?

The semicircular canals.

What structures in the inner ear detect linear acceleration and gravitational forces?

The otolith organs (utricle and saccule).

What is a receptor potential?

A graded electrical change produced by a sensory receptor in response to a stimulus.

What is the primary purpose of the auditory system?

To detect changes in air pressure over time and interpret them as pitch, loudness, and sound location.

Why can neurological damage selectively affect one type of sensation?

Because different submodalities use distinct receptor types, neural pathways, and brain processing regions.