Neutral and Hormonal Systems

Biology, Behavior, and Mind

LOQ: Why are psychologists concerned with human biology?

• Hippocrates correctly identified that the mind was located within the brain

• Aristotle believed that the heart was where the mind was, pumping warth throughout the body

• Franz Gall, a German physician, proposed that phrenology, the study of bumps on the skull, was a way to see the person’s mental abilities as well as their charateristics, during the early 1800s

  • The UK had 29 different phrenological societies during one time that went all around North America and gave skull readings.

• Phrenology succeed in brining attention that different regions of the brain have various functions

• Biological psychologists use new technologies that let them study the links between osycholigal process as well as biological (genetic, neural, hormonal) process

  • Within the past 100 years, they have been able to understand more of the biology of our mind and discovered things such as

    • Our brain is adaptive and is wired by out experiences

    • The body and nerve cells that conduct electricity “talk” to each other and send chemical messages across a small gap

    • specific brain systems serve specific functions (not the functions that Gall supposed)

    • Integrated information processed in the different systems of the brain construct our experiences of sights, sounds, meanings, memories, pain, and passion.

Biological Pyschology: the scientific study of the links between biological (genetic, neural, hormonal) and psychological processes. Some biological psychologists call themselves behavioral neuroscientist, neuropsychologists, behavior geneticists, physiological psychologist, or biopsychologists.

• We are biopsychosocial systems and we need to understand the ability to the brain to rewire itself to understan our behavior

The Power of Plasticity

LOQ: How do biology and experience interact?

• Our brains are sculpted by our genes as well as our life

  • This neural change of building new pathways is called plasticity

• Plasticity is what makes the brain in humans unique (Gómez- Robles et al. 2015)

  • Our brains change more than any other species

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

Neural Communication

Neurons

LOQ: What are neurons, and how do they transmit information?

• Our neural informations system is made out of building blocks called neurons, or nerve cells

  • New neurons are born and unused neurons wither and die

  • Neurons are all variations of the same theme

  • They all are made of a cell body and its branching fibers

    • Bushy dendrite fibers receive and integrate information to the cell body

      • Then the cells signal is passed through the axon fiber and spreads to other neurons, muscles, or glands

      • Dendrites listen. Axons speak

      • Axons can be very long (several feet through the body)

      • Some axons are encased in a myelin sheath that isulates them and speeds the impulses

    • Glial cells “glue cells” support billions of nerve cells

      • They also play a role in learning, thinking, and memory

      • They “chat” transmit information and memory

Cell Body: the part of a neuron that contains the nucleus; the cell’s life-support system center

Dendrites: a neuron’s often bushy, branching extensions that receive and integrate messages, conducting impulses toward the cell body

Axon: the meuron extension that passes messages through its branches to other neurons or to muscles or glands.

Myelin Sheath: a fatty tissue layer segmentally encasing the axons of some neurons; enables vastly greater transmission speed as neural impulses hop from one node to another

Glial Cells (Gila): cells in the nervous system that support, nourish, and protect neurons; they also play a role in learning, thinking, and memory

The Neural Impulse

• Neurons send messages when stimulated by our senses or from nearby neurons

  • These impulses are called the action potential

• Neurons generate electricity from chemical events

• Most neural signals are exitatoey, like pushing a neuron’s gas pedal

• Some are inhibitory, like pushing its brake

• Is the excitatory signals exceed the inhibitory signals by a minimum level, threshold, combine the signals to trigger an action potential

• Neurons need very short breaks (fractions of an blink)

  • This is called the refractory period and no action potientals can occur until the axon returns to its resting state.

Action Potential: a neural impulse; a brief electrical charge that travels down an axon

Threshold: the level of stimulation required to trigger a neural impluse

Refractory Period: in neural processing, a brief resting pause that occurs after a neuron has fired; subsequent action potentials cannot occur until the axon returns to its resting state

All-Or-None Response: a neuron’s reaction of either firing (with a full-strength response) or not firing

How Neurons Communicate

LOQ: How do nerve cells communicate with other nerve cells?

• Scientist used to believe that the axon of one cell fused with the dendrites or another in an uninterrupted fabric

  • British psychologist, Sir Charles Sherrington (1857-1952) noticed that neural impulses took an unexpectedly long time to travel a neural pathway

    • He inferred that a brief interruption in the transmission, he called the connection point of neurons a synapse

  • We now know that the axon terminal of one neuron is separated from the receiving neuron by the synaptic gap

• Neurotransmitters cross the synaptic gap and join to receptor sites on the receiving neurons

  • Excess neurotransmitters dift away, broken down by enzymes, or reabsored by sending neurons through a process called reuptake

Synapse: the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. The tiny gap at this junction is called the synaptic gap or synaptic cleft.

Neurotransmitters: chemical messengers that cross the synaptic gaps between neurons. When released by the sending neuron, neurotransmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether that neuron will generate a neural impulse.

How do Neurotransmitters Influence Us

LOQ: How do neurotransmitters influence behavior, and how do drugs and other chemicals affect neurotransmisson?

Neurotransmitter systems interact and the effects vary with the receptors they stimulate

• Acetylcholine (ACh) plays a role in learning and memory

  • Also the messenger at junction between motor neurons

• Reasearcher confirmed that the brain produces its own naturally occurring opiates

  • Many of these are similar to morphine in response to pain and vigorous exercise

    • Endorphins explain good feelings such as “runner’s high”, painkilling effects of acupuncture, and indifference to pain in some severely injured people

Endorphins: “morphine withing” - natural, opiate-like neurotransmitters linked to pain control and to pleasure

How Drugs and Other Chemicals Alter Neurotransmission

• Flooding “feel-good” artificial opiates into the brain causes an imbalance of the brain’s naturally opiates

  • This may cause the brain to stop producing their own opiates which causes intense discomfort when withdrawing from the drugs

• Agonist molecules increase the actions of neurotransmitters, or block reuptake in the synapse

  • Other agonist are enough to act like the natural neurotransmitter to join its receptor and mimic its excitatory or inhibitory effects.

• Antagonists decrease a neurotransmitter’s action by blocking production or release

  • Botulin causes paralysis by blocking ACh release

  • These antagonists are enough to act like the natural neurotransmitter to occupy its receptor site and block its effect, but isn’t similar enough to stimulate the receptor

Agonist: a molecule that increases a neurotransmitter’s action

Antagonists: a molecule that inhibits or blocks a neurotransmitter’s action

The Nervous System

LOQ: What are the functions of the nervous system’s main divisions, and what are the three main types of neurons?

Nerves communicating with neurotransmitter causes our nervous system to wake up

• It takes in information around us and the body’s tissues to make decisions

• The brain and spinal cord form the central nervous system (CNS), body’s decision maker

• Peripheral nervous system (PNS) gathers information for transmitting CNA dexcions to other body parts

• Nerves form groups of axons and links the CNS with the body’s sensory receptors, muscles, and glands

  • Optic nerves gather million axons into a single message from the eye to the brain

Information travels through three types of neurons

• Sensory neurons carry messages from sensory receptos and body tissue inward (they are afferent) to the brain and spinal cord for processing

• Motor neurons (which are efferent) carry directions to the muscles and glands from the CNS

• Interneurons process sensory input and motor output

Central Nervous System: the brain and spinal cord

Peripheral Nervous System (PNS): the sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body

Nerves: bundled axons that form neural cables connecting the central nervous system with muscles, glands, and sense organs.

Sensory (Afferent) Neurons: neurons that carry incoming information from the body’s tissues and sensory receptors to the brain and spinal cord.

Motor (Efferent) Neurons: neurons that carry outgoing information from the brain and spinal cord to the muscles and gland.

Interneurons: neurons within the brain and spinal cord; they communicate internally and process information between the sensory inputs and motor outputs.

The Peripheral Nervous System

The peripheral nervous system has two parts

• Somatic nervous system

  • Enables voluntary control of our skelatal muscles

• Automatic nervous system (ANS)

  • Controls our glands and our internal organ muscles. ANS influences functions such as glangulat activity, heartbeat, and digestion (Automatic means “self-regulating”)

    • May be consciously overridden

  • Also has two parts

    • Sympathetic nervous system

      • Arouses and gives off energy

      • Can increases heartrate, raise blood pressure, slow digestions, raise blood sugar, and make you sweat

        • Once this is over, patasympathatic nervous system will start reversing opposite effects

    • Parasympathetic nervous system

      • Conserves energy as it calms you

    • Sympathetic and parasympathetic nervous system work together and maintain homeostasis

Sympathetic Nervous System: the division of the autonomic nervous system that arouses the body, mobilizing its energy

Parasympathetic Nervous System: the division of the autonomic nervous system that calms the body, conserving its energy.

The Central Nervous System

The brain’s neurons gather into groups called neural networks.

• Neurons network with close neurons to have quick connections

The spinal cord both sends and receives information connecting to the peripheral nervous system as well as the brain.

• Ascending (rising) neural fiber send sensory information

• Descending (lowering) fibers send motor-control information back

• The neural pathways govern our reflexes

Reflex: a simple, automatic response to a sensory stimulus, such as the knee-jerk response.

The Endocrine System

LOQ: How does the endocrine system transmit information and interact with the nervous system?

Endocrine System: the body’s “slow” chemical communication system; a set of glands that secrete hormones into the bloodstream

Hormones: chemical messages that are manufactured by the endocrine glands, travel through the bloodstream, and affect other tissues

The endocrine and nervous system are close relatives

• Both produce molecules acting as receptors elsewhere

• The nervous system is faster at sending messages

• Messages from the endocrine are very slow when they move through the bloodstream

  • Endocrine messages last longer than the effects of neural messages

The ANS tells to adrenal glands to release epinephrine and noreprinpheren (a.k.a. Adrenaline and noradrenaline)

• Located on the kidneys

• These increase heart rate, blood pressure, and blood sugar, giving off a surge energy

• The pituitary gland is the most influential endocrine gland and is located in the core of the brain

  • Directs other endocrine glands to secrete hormones

• The pituitary is a growth hormone that stimulates the physical aspects of development

• Oxycotin enables contractions with birthing, the flow of breastmilk, and orgasms

  • Also promotes pair bonding, group cohesion, as well as social trust

Pituitary Gland: the endocrine system’s most influential gland. Under the influence of the hypothalamus, the pituitary regulates growth and controls other endocrine glands.

Tools of Discover, Older Brain Structures, and the Limbic System

The Tools of Discovery: Having Our Head Examined

LOQ: How do neuroscientists study the brain’s connections to behavior and mind?

Scientists have been able to develop new tools and technology to research the brain without causing permanent damage

• They can selectively lesion (destroy) tiny groups of irregular or regulat brain cells without hurting the cells around them

• They can also stimulate various parts of the brain through electricity, chemically, and magnetical

• They can also look at the messages of individual neurons.

• Optogentics is a technique that allows neuroscientis to have the ability to control individual neurons activity

• An electroencephalogram (EEG) allows scientist to see the electrical activity in your brain

  • This lets them see electrical wakes caused by the stimulus

• A magnetoencephalgraphy (MEG) mesuaasres the magnetic fields from the natural electrical activity in the brain

  • The do this in a room that cancels out all other magnetic signals

  • This allows them to understand how specific tasks influence brain activity

• PET (positrion emission tomography) scan shows the brain activity by showing the each are of the brain’s consumption of its chemical fuel

  • PET scans can track the gamma rays releases from the radioactive glucose

  • Shows “hot-spots” of the most active areas of the brain

• MRI (magnestic resonance imaging) brain scans use strong magnetic fields around your head

  • This aligns the spinning atoms in the brain molecules

  • A radio-wave pluse then temporarily disorients the atoms

  • When the atoms return to normal, they emit signals that show detailed pictures of soft tissues

• Special uses of MRI is called fMRI (functional MRI)

  • This shows brain sturutce and and fucntions

All of these scans for the brain show us how the brain works in different parts of the area and causes of psycholocgical disorders

Lesion: tissue deconstruction. A brain lesion is a naturally or experimentally caused destruction of brain tissue

Electroencephalogram (EEG): an amplified recording of the waves of electrical activity sweeping across the brain’s surface. These waves are measured by electrodes placed on the scalp.

Magnetoencephalography  (MEG): a brain-imaging technique that measures magnetic fields from the brain’s natural electrical activity.

PET (Positron Emission Tomography) Scan: a visual display of brain activity

MRI (Magnetic Resonance Imaging): a technique that uses magnetic fields and radio waves to produce computer-generated images of soft tissue. MRI scans show brain anatomy.

fMRI: a technique for revealing blood flow and, therefore, brain activity by comparing successive MRI scans. fMRI scans show brain function as well as structure.

Older Brain Structures

LOQ: What structures make up the brainstem, and what are the functions of the brainstem, thalamus, recticular formation, and cerebellum?

The Brainstem

The brainstem is the brains oldest and innermost regions

• Base is in the medulla

• The controls for heartbeat and breathing are located here

• Above the medilla is the pons which helps corrediante movements and control sleep

• The crossover point

  • Most nerves to and from both sides of the brain join and connect with the body’s opposite side

Brainstem: the oldest part and central core of the brain, beginning where the spinal cord swells as it enters the skull; the brainstem is responsible for automatic survival functions

Medulla: the base of the brainstem; controls heartbeat and breathing.

The Cerebellum

The cerebellum allows for nonverbal learning, skill memories, judge time, modulate our emotions, and differentiate the differences between sounds and textures

• Would have difficulty walking, keeping balance, and shaking hands if your cerebellum was damaged

Cerebellum: the “little brain” at the rear of the brainstem; functions include processing sensory input, coordinating movement output and balance, and enabling nonverbal learning and memory.

The Limbic System

LOQ: What are the limbic system’s structures and functions?

The limbic system is between the cerebral hemispheres.

• This system contains the amygdala, the hypothalamus, and the hippocampus

Limbic System: neural system (including the amygdala, hypothalamus, and hippocampus) located below the cerebral hemispheres; associated with emotions and drives.

The Amygdala

The amygdala is linked to aggression and fear

• Peopel with amygdala lesions usually show decreased arousal to fear and anguring-arousing stimuli

• One study showed that it has found that math anxiety and hyperactivity

• Some studies link criminal behaviors with amygdala dysfunctions

Amygdala:

two lima-bean-sized neural clusters in the limbic system; linked to emotion.

The Hypothalamus

Hypothalamus is a important link in the communication and command chain ruling over boldly maintenance, such as hunger, thirst, body temperature, and sexual behavors

• There are different areas for each of the body maintenaces

• Later experiments found what is now called “reward centers” (used to be called “pleasure centers”)

• Some research shows that by stimulating the “hedonic hotspots” (reward circuits) in the brain produce more desire than just pure enjoyment

• Some researchers believe that substance use may develop from malfunctions in the natural rewards and pleasure in the brain

Hypothalamus: a neural structure lying below (hypo) the thalamus; it directs several maintenance activities (eating, drinking, body temperature), helps govern the endocrine system via the pituitary gland, and is linked to emotion and reward.

The Hippocampus

Processes conscious, explicit memories

• Decreases in size and function as we age

• People can lose their hippocampus from surgery or an injury

  • This can lead to them not being able to develop new memories of events and news

  • Children that survived a hippocampal brain tumor often don’t rember new information in their current adult life.

Hippocampus: a neural center located in the limbic system; helps process explicit (conscious) memories—of facts and events—for storage.

The Cerebral Cortex

LOQ: What four lobes make up the cerebral cortex, and what functions of the motor cortex, somatosensory cortex, and association areas?

Old brain networks sustain simple life functions and enable memory, emotions, and basic drives.

• Newer neural connections located in the makes up 85% of the brain’s weight and forms specalised groups the change our perception, thinking, and speaking

The Cerebral Mantle is a thin layer of interconeccted neural cells

The cerebral cortex is relivily new in the evolutions of the human brain.

• It’s the brain’s thinking hat and the untilamte control and information- processing cnter of your body

Cerebral Cortex: the intricate fabric of interconnected neural cells covering the cerebral hemispheres; the body’s ultimate control and information-processing center.

Stutucture of the Cortex

Each hemisphere of the cortex is divided into four different lobes and each lobe is separated from prominent folds of fissures

• Top and and frontal lobes (behind your forehead)

• Parietal lobes (top and back of the brain)

• Occipital lobes (back of the head)

• Temporal lobes (above your ears)

• All of these lobes carry out different rols and work together for different functions

Frontal Lobes: the portion of the cerebral cortex lying just behind the forehead; involved in speaking and muscle movements and in making plans and judgments.

Parietal Lobes: the portion of the cerebral cortex lying at the top of the head and toward the rear; receives sensory input for touch and body position.

Occipital Lobes: the portion of the cerebral cortex lying at the back of the head; includes areas that receive information from the visual fields.

Temporal Lobes: the portion of the cerebral cortex lying roughly above the ears; includes the auditory areas, each receiving information primarily from the opposite ear.

Functions of the Cortex

Motor Functions

Gustav Fritsch and  Eduard Hitzig discovered the motor cortex

• Ran several experiments in 1870 when they found out about the mortar cortex

Motor Cortex: an area at the rear of the frontal lobes that controls voluntary movements.

Mapping the Motor Cortex

The brain has no sensory receptors

• In the 1930s, Otfrid Foster and Wilder Penfield mapped out the motor cortex on hundreds of patients that were fully awake\

  • They did this by stimulating cortical areas and then observing the response

  • Discovered body areas that required precise control such as the fingers and mouth

• Jośe Delgado stimulated a spot on a patients left morot cotex

  • This caused the paitents right hand to make a fist

  • Delgado asked for the ptietns to keep his fingers open but he wasn’t able to

Findings of how the motor cortex can be controlled has let research on brain-controlled computer technology to begin experimenting

Brain-Computer Interfaces

This research and experimentation has let scientists to help benefit people

• Were able to have humans control a robotic arm and a wheelchair that would help them obtain food

Research has recorded messages from the brain area in control of planning and intention.

• This could be helpful in patients that cannot speak but are still able to think (ex after a stroke)

• Richard Andersen and his colleagues have theorized that if researches were able to implant electrodes in speech areas and then ask the patients to “think of differnt words” and then they would be able to see how the cells fire in different ways

  • You would then be able to take this data and research and turn it into a speech synthisizer

  • There have been clinical trials of cognitive nerual prothetics being tested in patients with severe paralasis or have lost a limb

Sensory Functions

The somatosensory coretex specializes in receiving information from sense on the skin such as touch, temperature, and movements of body parts

• The more sensitive the body region, the larger the somatosesory area speciallized for it

Somatosensory Cortex: an area at the front of the parietal lobes that registers and processes body touch and movement sensations.

Association Areas

Neurons in this area working with higher mental functions that make us human

• Association areas cannot be neatly mappes unlike somatosensory and motor areas

• Can preform other mental functions

  • Ex. paitnets wanting to move an uper limb, lips, or their tongue without any actual movement

    • With more stimulation patients thought they had moved but never did

  • Allows us to recognize faces

Prefrontal cortex in the frontal lobes enables judgment, planning, and processing of new memories

• Frontal lobe damage can alter personality and remove a person’s inhibitions

  • Studies on this notice less inhibited as well as their moral judgments might be unrestrained

• People with damaged frontol lobes might have high intelligence test scores and good cake baking skills

  • They wouldn’t be able to plan ahead to start making the cake and if they do start baking it, the recipe might be forgotten

Association Areas: areas of the cerebral cortex that are not involved in primary motor or sensory functions; rather, they are involved in higher mental functions such as learning, remembering, thinking, and speaking.

Responses to Damage

LOQ: To what extent can a damaged brai reorganize itself, and what is neurogenesis?

Most brain-ddmanged effects are from two facts

• Severed brain and spinal cord neurons that usually don’t regertatte unlike skin \

  • If your spinal cord was severed you would most likely be permanently paralazed

• Some brian functions seem preassigned to areas

  • Some neural tissue can reogranize from the cause of the damage

Plasticity also sometimes occur after severe damage

• Happens alot in young children

• Constraint-induced therapy trys to rewire brians and also improve the dexterity of a damaged brain

• It can be good for people who suffer from blindeness or deafness

  • It allows the parts of the brains where these functions were dedicated to and allow other functions be able to become usable for other sense and areas of the brain

Nuclear test during 1945-1963 during the Cold War later allowed scientiis to confrim the creation of new brain neurons

• Since then scientits have been able to discover that 700 new neurons are born every day in the hippocampus (almost a 2% turnover rate yearly)

Master stem cells can develop into any type of brain cell

• These have been discovered in human embryos

• Reasearchers have been able to produce stem cells the are similar to fuctionging human neurons

  • This could help treat diseases or damaged brains

  • Also helps to understand brain development, memory, and other simple psychological processes

Neurogenesis: the formation of new neurons

The Divided Brain

LOQ: What do split brains reveal about the functions of our two brain hemispheres?

Splitting the Brain

In 1961, Phillip Vogel and Joseph Bogen thought that major epeleptic seizures were caused from abnormal brain activity moving from the two cerebral hemispheres

• They wondered if severing the corpus callosum

• After the operation the seizures dissapeared and the paitents with “split brains” were normal and their intelligence and personality traits weren’t effected at all

Corpus Callosum: the large band of neural fibers connecting the two brain hemispheres and carrying messages between them.

Split Brain: a condition resulting from surgery that isolates the brain’s two hemispheres by cutting the fibers (mainly those of the corpus callosum) connecting them.

Right-Left Brain Differences in the Intact Brain

Each side of our hemispheres perform different functions

• When a perceptual task is performed a brain scans usually often shows increased brain activity (brain waves, blood flow, and glucose use) in the right hemisphere

• When a person speak or does a math equation, activity usually increase in the left hemisphere