Psych 100 U4 Biological Bases of Behaviour

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Questions and Answers

What is the effect of damage to Broca's area?

Inability to produce any speech

Telegraphic speech (correct)

Difficulty understanding language

Fluent but nonsensical speech

What condition results from damage to Wernicke's area?

Difficulty in reading comprehension

Total loss of speech

Fluent but nonsensical speech (correct)

Poor memory retention

Which of the following was a belief of phrenologists?

The brain does not change with experience

Mental traits can be measured by skull shape (correct)

All personality traits are fixed at birth

Brain functions are entirely localized in one area

What do we know about complex behaviors according to modern neuroscience?

They emerge from the interaction of multiple brain regions Signup and view all the answers

What misconception did phrenology promote regarding the brain?

The skull shape determines personality traits Signup and view all the answers

What structure connects the left and right hemispheres of the cerebral cortex?

Corpus Callosum Signup and view all the answers

What does contralateral organization in the brain refer to?

Each hemisphere controls the opposite side of the body Signup and view all the answers

Which function is primarily associated with the left hemisphere of the brain?

Language skills Signup and view all the answers

What is the primary purpose of the split-brain procedure?

To limit the extent of seizures Signup and view all the answers

How do split-brain patients respond when a visual stimulus is presented in the left visual field?

They can identify it with the left hand but cannot say what it is Signup and view all the answers

What significant evidence do strokes provide regarding the two hemispheres?

Right hemisphere damage leads to deficits in recognizing faces Signup and view all the answers

Which statement best describes the interaction between the two hemispheres of the brain?

They communicate through the corpus callosum for coordination Signup and view all the answers

What phenomenon occurs in split-brain patients when information is given to only one hemisphere?

Behavior indicative of having two separate minds Signup and view all the answers

What is the relationship between thicker cerebral cortices and learning capacity?

Thicker cortices are associated with enhanced learning capacities. Signup and view all the answers

What occurs during critical periods of brain development?

Neural connections change more significantly. Signup and view all the answers

What is damage plasticity?

Modification and reorganization of neural pathways after injury. Signup and view all the answers

How does extensive spatial learning affect hippocampal size?

It is linked to an increase in hippocampal size. Signup and view all the answers

What happens in the brain after an amputation, as observed in phantom limb syndrome?

Adjacent brain regions take over the cortical space left vacant. Signup and view all the answers

What is the primary function of sensory neurons?

Transmit messages from sensory organs to the spinal cord and brain. Signup and view all the answers

Which part of the neuron is responsible for transmitting electrical impulses?

Axon Signup and view all the answers

What triggers the release of neurotransmitters from the presynaptic neuron?

The arrival of the action potential at the axon terminal. Signup and view all the answers

What does the all-or-nothing response refer to in the context of action potentials?

An action potential either occurs at full strength or not at all. Signup and view all the answers

What is the role of glial cells in the nervous system?

Providing structural support and cleaning up debris. Signup and view all the answers

What happens during depolarization of a neuron?

Positively charged sodium ions enter the neuron. Signup and view all the answers

Which neurotransmitter is primarily involved in the fight or flight response?

Norepinephrine Signup and view all the answers

What is the primary inhibitory neurotransmitter in the human brain?

GABA Signup and view all the answers

How does the myelin sheath affect action potentials?

It insulates axons and speeds up electrical signal transmission. Signup and view all the answers

What is the function of the refractory period in action potential propagation?

It ensures the action potential moves forward. Signup and view all the answers

What consequence can arise from excess norepinephrine?

High blood pressure and anxiety. Signup and view all the answers

What mechanism is NOT involved in tidying up the synapse after neurotransmission?

Replication of neurotransmitters in the postsynaptic neuron. Signup and view all the answers

What can low levels of acetylcholine lead to in the brain?

Dementia associated with Alzheimer’s disease. Signup and view all the answers

What is the primary role of the medulla in the brainstem?

Controlling heart rate and blood pressure Signup and view all the answers

Which brain structure is primarily involved in processing emotional significance of sensory information?

Amygdala Signup and view all the answers

Which lobe of the brain is responsible for auditory processing and understanding language?

Temporal lobe Signup and view all the answers

What function does the hypothalamus serve?

Maintaining homeostasis and biological rhythms Signup and view all the answers

The primary motor cortex is located in which part of the brain?

Frontal lobe Signup and view all the answers

Which structure is known as the 'emotional brain'?

Limbic system Signup and view all the answers

What is the role of the primary somatosensory cortex?

Mapping the body's skin surface for touch sensations Signup and view all the answers

Which structure in the brain is responsible for planning, executing, and controlling voluntary movement?

Basal ganglia Signup and view all the answers

What effects can oxytocin have on trust in social situations?

It can decrease trust towards out-group members. Signup and view all the answers

Which lobe primarily manages visual processing and interpretation?

Occipital lobe Signup and view all the answers

What is the function of the insular lobe?

Perception of the internal state of the body Signup and view all the answers

What phenomenon results from damage to the amygdala?

Loss of emotional significance in visual stimuli Signup and view all the answers

Which area of the brain is known for relaying sensory signals to higher brain regions?

Thalamus Signup and view all the answers

Which of the following best describes the effects of frontal lobotomies?

Lead to emotional blunting and impulsive behavior Signup and view all the answers

What is the primary function of an agonist in neurotransmission?

Mimics neurotransmitters and activates receptors Signup and view all the answers

How does the body respond during the fight-or-flight reaction initiated by the sympathetic nervous system?

Increased heart rate and pupil dilation Signup and view all the answers

What role does oxytocin play in relation to social bonding in prairie voles?

Stimulates uterine contractions during birth Signup and view all the answers

What effect does repeated use of opioid drugs have on receptor structure?

Decreases the number of receptors Signup and view all the answers

What is the main function of the parasympathetic nervous system?

Regulates involuntary bodily functions Signup and view all the answers

Which gland is often referred to as the 'master gland' of the endocrine system?

Pituitary gland Signup and view all the answers

What physiological changes are primarily caused by the release of adrenaline during stressful events?

Increased energy and heightened alertness Signup and view all the answers

In the context of opioid addiction, what shifts in behavior occur as tolerance develops?

From positive to negative reinforcement Signup and view all the answers

What distinguishes prairie voles from montane voles in terms of social behavior?

Prairie voles show pair bonding; montane voles do not Signup and view all the answers

What happens to the number of oxytocin receptors in the brain of prairie voles compared to montane voles?

Prairie voles have a higher density of receptors Signup and view all the answers

How do adrenal hormones like cortisol function during stressful situations?

They increase alertness and provide immediate energy boosts Signup and view all the answers

What characterizes the autonomic nervous system?

Operates without conscious control Signup and view all the answers

Which of the following is a primary role of hormones in the endocrine system?

Serve as slower acting chemical messengers Signup and view all the answers

What effect does increased density of oxytocin receptors have on prairie voles?

Enhances pair bonding and biparental care Signup and view all the answers

Study Notes

The Biological Bases of Behaviour

The nervous system is a complex network of nerves, or bundles of neurons, controlling all bodily functions.
Neurons are specialized cells for sending and receiving neural messages. There are approximately 100 billion neurons in the brain, creating over 100 trillion connections.
Sensory neurons transmit messages from sensory organs (eyes, tongue, skin) to the spinal cord and brain.
Motor neurons carry messages from the brain and spinal cord to muscles and glands.
Interneurons collect, integrate, and retrieve messages within the brain and spinal cord.

Structure of Neurons

Dendrites receive chemical messages from other neurons.
The cell body, or soma, collects neural impulses, contains the nucleus, and sustains cellular functions.
Axons transport electrical impulses to other neurons through terminal branches.
Axon terminals/terminal branches transform electrical signals into chemical messages for other neurons.
Myelin sheath is a fatty insulating layer that speeds up the transmission of electrical signals.

Glial Cells

Glial cells provide structural support and scaffolding for neurons.
They also clean up debris, form the blood-brain barrier, facilitate communication between neurons, provide nourishment, and insulation.

The Action Potential

Neurons communicate via electrical impulses called action potentials.
Action potentials originate at the junction between the axon and cell body and travel down the axon to its terminal.
At the terminal, they trigger the release of chemical messages to neighbouring cells.

Cell Membrane

The cell membrane encloses the neuron and separates the intracellular fluid from the extracellular fluid.
Intracellular and extracellular fluids contain charged particles (ions) like sodium (Na+), chloride (Cl-), potassium (K+), and calcium (Ca2+).
The membrane is selectively permeable, meaning it allows some ions to pass through but not others.

Before an Action Potential

At rest, more negatively charged particles are inside the cell compared to the outside.
The resting potential is the electrical charge across the membrane, approximately -70 millivolts.
A neuron cannot fire an action potential in this resting state.

Beginning Depolarization

When the neuron is sufficiently stimulated by other neurons, ion channels open at the axon end.
Positively charged sodium ions (Na+) enter the cell.
The electrical charge across the membrane reverses, initiating depolarization.

Action Potential

Voltage threshold is the critical level of depolarization needed to initiate an action potential, about -55 mV.
Once the threshold is reached, voltage-gated ion channels open, allowing positively charged sodium ions (Na+) to flood into the cell.
The action potential's peak involves a more positive charge inside the cell than outside.
It's an all-or-none response.

Repolarization

Depolarization triggers the closing of sodium channels, but potassium (K+) channels remain open.
Potassium ions (K+) flow out of the cell, causing repolarization.
This process leads to a temporary dip below the resting potential, a characteristic of the refractory period making it difficult for the neuron to fire again immediately.

Propagation of the Action Potential

The action potential travels along the axon.
Myelination speeds up the process by allowing the signal to "jump" between nodes.
The refractory period ensures the action potential propagates in one direction.

Communicating Across the Synaptic Cleft

The synaptic cleft is the gap between neurons.
An electrical signal must be converted to a chemical one to cross this gap.
Presynaptic neurons release chemical messengers called neurotransmitters.
Neurotransmitters bind to receptors on the postsynaptic neuron, which are channels in the membrane that bind specific neurotransmitters.

Tidy Up the Synapse

Neurotransmitters need to be removed from the synapse to terminate the chemical message.
Neurotransmitters are cleared through diffusion (drifting out), degradation (breakdown), or reuptake (reabsorption into the presynaptic terminal branches).

Excitation & Inhibition

Interactions between neurotransmitters and receptors either excite or inhibit the receiving neuron.
Excitation slightly depolarizes the neuron, making it more likely to fire an action potential.
Inhibition slightly hyperpolarizes the neuron, reducing the likelihood of firing.

Types of Neurotransmitters

Major classes of neurotransmitters include amino acids (e.g., GABA), acetylchoine, monoamines (e.g., norepinephrine, serotonin, dopamine), neuropeptides, and endorphins.

GABA, Acetylcholine, Norepinephrine, Serotonin, Dopamine

GABA is the most prevalent inhibitory neurotransmitter, influencing stress, anxiety, and fear responses. Sedative drugs target GABA receptors while alcohol promotes GABA activity.
Acetylcholine plays roles in both excitatory and inhibitory signals, muscle movement, and autonomic nervous responses; low levels are associated with Alzheimer's disease.
Norepinephrine is crucial for the "fight or flight" response. Elevated levels can lead to anxiety and high blood pressure.
Serotonin regulates sleep, appetite, mood, and aggression and may play a role in depression but the precise mechanism is still unclear.
Dopamine is involved in movement, planning, reward, and plays a part in addictive behaviours; high levels correlate with schizophrenia, while low levels are linked to Parkinson's disease.

Endorphins

Endorphins are "endogenous morphine," prompting feelings of pleasure and reducing pain.

Psychoactive Drugs

These substances influence thoughts, feelings, and behaviour by affecting neurotransmitter function.
They include prescription medications, street drugs, caffeine, nicotine, and alcohol.

Agonists & Antagonists

Agonists enhance neurotransmitter effects by increasing release, blocking reuptake, or mimicking neurotransmitters to activate postsynaptic receptors.
Antagonists inhibit neurotransmitter effects by blocking release, destroying neurotransmitters in the synapse, or mimicking neurotransmitters to block the binding to postsynaptic receptors.

Model of Opioid Addiction

Opioid drugs hijack the reward system triggering tolerance to the drug and eventually a shift from positive reinforcement in taking the drug to alleviate negative feelings (withdrawal).
Repeated use can change receptor structure, leading to a reduction in receptor number and sensitivity.

Nervous System

The nervous system is a complex network of nerves (bundles of neurons) that control and regulate all bodily functions.
Subdivisions include the central nervous system (CNS) comprising the brain and spinal cord, and the peripheral nervous system (PNS), which includes nerves connecting the brain to the rest of the body.
PNS can be further divided into somatic and autonomic nervous systems - somatic enables voluntary body movements and brings sensory information to the CNS; autonomic enables involuntary control of organs and glands.

Peripheral Nervous System

Somatic nervous system—controls voluntary movement from the CNS to muscles and brings sensory input to the CNS..
Autonomic nervous system—controls involuntary organs, glands, and blood vessels. Further subdivided into sympathetic and parasympathetic branches.

Sympathetic Nervous System

Prepares the body for situations requiring energy expenditure (fight-or-flight response). This can be seen by pupil dilation, increased breathing, heart rate & blood flow to muscles - redirecting energy away from non-essential processes like digestion.

Parasympathetic Nervous System

Calms the body and returns it to a resting state (rest-and-digest). It controls glands, organs & returns the body to a resting state or "rest and digest" mode. Includes nutrient storage, digestion and growth.

Endocrine System

The endocrine system comprises glands that work in conjunction with the CNS and PNS.
Hormones are the blood-borne chemical messengers secreted by the endocrine system. Hormones travel over greater distances and are slower than CNS neurotransmitters.

Adrenal Hormones

Adrenal glands, atop the kidneys, release adrenaline (epinephrine) during stress & cortisol.
Adrenaline boosts energy, increases heart rate, blood pressure and blood sugar levels.
Cortisol has a slower onset but longer lasting effects compared to adrenaline.

Pituitary Gland

The pituitary gland directs other glands and regulates various bodily functions, like hunger, sexual arousal, growth, sleep (often via the pineal gland), and social behaviour.

Oxytocin

Hormone released by the pituitary gland.
Involved in parturition (uterine contractions during birth).
Promotes lactation & considered crucial for social bonding.

A Tale of Two Voles

Prairie voles exhibit strong pair bonding and parental care, due to a higher density of oxytocin receptors in reward-related brain areas.
Montane voles, conversely, do not exhibit consistent pair-bonding but have less oxytocin receptors compared to prairie voles.

What About Humans?

Research has shown that intranasal oxytocin can increase trust in economic trust games in humans, including generating acts of generosity and cooperation.

Not So Fast!

The effects of oxytocin agonists in humans are not always consistent and can even sometimes result in negative or antisocial effects.

Brain Stem, Midbrain, Pons, Medulla Oblongata

The brainstem is the lowest region of the brain, atop the spinal cord, responsible for vital functions; damage can be lethal.
Key brainstem structures include the Midbrain, Pons & Medulla.
- Midbrain handles orientation to stimuli, movement, motivation and reward, and down-regulates pain signals.
- Pons manages breathing, balance, coordination, and relaying certain sensations (hearing, taste) to higher brain areas.
- Medulla governs heart rate, blood pressure, and reflex activity like swallowing, coughing.

### Cerebellum

Regulates coordination, balance, precise movements, and accurate timing of those movements.

Limbic System

The limbic system, or the "emotional brain”, controls various emotions including basic drives; it includes Hypothalamus, Thalamus, Amygdala, Hippocampus and Basal Ganglia.

Hypothalamus

Acts as an interface between the brain & body controlling homeostasis like thirst, hunger, temperature regulation and rhythms. It also manages motivation, reward-seeking, and the fight-or-flight responses. It communicates with the autonomic and endocrine systems.

Thalamus

The thalamus serves as a relay station for virtually all sensory information (except smell) and is important for alertness and consciousness.

Amygdala

Processes the emotional significance of sensory information, responding to both positive and negative stimuli and working with the hippocampus creating vivid memories. Damage can lead to psychic blindness.

Hippocampus

Supports spatial navigation and mental time travel. crucial for forming lasting memories.

Basal Ganglia

Involved in planning and executing voluntary movements, and suppressing unwanted movements.
Plays a role in reward and pleasure.

Cerebral Cortex

The outermost and largest region of the brain, divided into four main lobes, and the insular lobe:
- Frontal lobe—responsible for complex thought, planning, control of movement, and map of the body's muscles, and executive function.
- Parietal lobe—deals with touch, spatial awareness, and a map of the body's skin surface.
- Temporal lobe—processes hearing, object memory, and language.
- Occipital lobe—visual processing and sight analysis.
- Insular lobe—important for taste, internal organ awareness.

Primary Sensory Areas

The primary sensory areas are the first cortical areas receiving sensory signals from their associated nerves.
- Parietal lobe—somatosensory, processing touch.
- Occipital lobe—visual.
- Temporal lobe—auditory, olfactory.
- Insular lobe—taste.

Association Cortex

Integrates information from different sensory areas and existing knowledge to generate meaningful experiences.
Involved in multisensory integration (combining information from different senses).
Facilitates understanding sensation, action, language and abstract thought.

Organization of Primary Somatosensory & Motor Areas

Brain regions (maps) of body parts are organized topographically; adjacent body parts are represented by adjacent areas of cortex.

The Symmetrical Brain

Almost every structure in the brain is duplicated in the left and right portions (eg, cerebellum, thalamus, amygdala). The cerebral cortex is also divided into left and right hemispheres by a deep fissure.

Corpus Callosum

The corpus callosum is a bridge of fibers connecting the two cerebral hemispheres. Information is transferred between the two hemispheres.

Contralateral Organization

Primary sensory and motor functions are controlled by the opposite hemisphere of the brain—that is, the left hemisphere controls the right side of the body, and vice versa.

Lateralization

Some brain functions are specialized to either the right or left side of the brain, with areas on the left hemisphere particularly specialized for language, and analogous area in the right hemisphere specialised for non-verbal and visuo-spatial information processing.
This specialization is demonstrated by evidence from strokes.

Split Brain Procedure

Surgeons sever the corpus callosum to limit seizures, and this disrupts communication between hemispheres.
Individuals with split-brain behavior illustrate that hemispheres operate somewhat independently.

Broca's Area

Damage to Broca's area (in the left frontal lobe) leads to telegraphic speech (e.g., "I hungry").
Individuals with damage to Broca's area can still understand speech.

Wernicke's Area

Damage to Wernicke's area (in the temporal lobe) results in fluent but nonsensical speech, making it difficult to understand what they're saying.

Phrenology

19th-century belief that mental faculties are located in specific skull regions, measurable through skull bumps.

What Phrenologists Got Wrong & Right

Modern science recognizes that the skull does not accurately represent brain regions. However, phrenology correctly identified the specialization of certain brain areas.

How Do We Study The Brain?

Methods for examining the brain include:

Neuropsychology (examining altered function following brain injury).
Brain stimulation (inducing lesions or altering activity, eg, deep brain stimulation, TMS, TDCS).
Functional imaging techniques, like PET and fMRI (examining brain activity, ie, blood flow and oxygenation).

Dissociation

A lesion to one brain area can disrupt one function without influencing another, signifying that individual brain areas have specific functions.
Double dissociation implies that damage to two different areas or structures disrupts two different, functionally independent functions.

Limitations of brain study methods

Naturally occurring brain damage might not be easy to limit and might over time spread over affected areas of the brain.
Generalizations from one person's brain might not be appropriate for everyone else in terms of brain behavior.

Non-Human Animal Studies

Studying non-human animals using electrical or chemical methods to induce lesions allows for the study of resulting behavioral changes.

Brain Stimulation Studies

Deep brain stimulation (DBS) involves stimulating specific brain areas with implanted electrodes, often for treatment of conditions such as depression.
Transcranial magnetic stimulation (TMS) applies magnetic pulses to stimulate or disrupt brain function, and is non-invasive.
Transcranial direct current stimulation (tDCS) uses direct current to modulate brain activity.

PET, fMRI, and Single-Cell Recording

Positron emission tomography (PET) injects radioactive tracers (like glucose) to visualize brain activity, showing higher concentrations of tracer in active areas.
Functional magnetic resonance imaging (fMRI) measures brain activity by detecting changes in blood oxygenation.
Single-cell recording measures the electrical activity of individual neurons, helping researchers understand the role of specific neurons in different tasks and abilities.

Electroencephalography (EEG)

Measures electrical wave activity of many thousands of neurons by placing electrodes on the scalp, diagnosing states like sleep or wakefulness.

EEG data analysis can reveal synchronized electrical responses to events. This provides insight into how the brain responds to stimuli or tasks.

Magnetoencephalography (MEG)

This method measures the magnetic fields produced by brain's electrical currents, allowing for greater temporal resolution.

Neural Plasticity

Neural plasticity is the brain's ability to change and adapt throughout life, reorganizing neural networks in response to learning, experience, and injury.
Critical periods are specific timeframes in development where the brain is receptive to environmental stimuli leading to greater changes in neural connections.

If You Use It, It Will Grow

Extensive spatial learning (eg, London cab drivers) is correlated with increased hippocampal size.

Damage Plasticity

Damage plasticity refers to neural modification or reorganization after injury eg, Phantom limb syndrome and brain regions taking over when others are affected.

### Additional Points

Methods with good spatial resolution have limited temporal resolution, while those with adequate temporal resolution have poor spatial resolution.
It's important to consider potential limitations and control conditions in interpreting the data obtained from imaging techniques.
Different research studies need to match the control conditions appropriately.

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