1. What is Biological Psychology?

• Biological psychology defines that the mind is what the brain does - monism
• Also known as behavioral neuroscience, biological psychology is the study of the reciprocal connections between the structure and activity of the nervous system and behavior and mental processes.
• behavior & cognitions and biology influences one another.
  • ghrelin is a type of hormone that gets released when we are hungry,
  • this hormone is sent to brain, and we respond to it by feeling hungry.
  • Icecream experiment tells us that the thought can influence biology as well.
    • when we are told that the ice cream is high calorie, after eating, we think we are full.

1-1. Early attempts to understand biological psychology

• History of psychology is driven by the advancements of technology like brain-imaging.
• Early attempts to understand biological psychology involved clinical examinations like autopsy.
• Artistotle (384-322 BCE) thought that the source of mind is located in heart.
• Phrenologists thought that the bumps on humans' skulls were the result of brains being used frequently, leading to bulging of certain parts of brains.
  • Though this idea is incorrect, relating specific part of brain to a specific function is considered correct today.

  1-2. Contemporary appraoches in Biological Psychology

• Anatomist Santiago Ramon y Cajal (1852-1934) and neurologist John Hughlings Jackson (1835-1911)
• Ramon y Cajal helped us understand microscopic level of the nervous system.
  • His idea of Neuron Doctrine proposed that nervous system was made up of separate cells instead of single continuous network.
• Jackson proposed that the nervous system is organized as hierarchy, with progressively more complicated behaviors being managed by more recently evolved and complex structures.
  • Drinking diminishes higher level areas of the brain that manages decisions making (complicated behavior),
  • which results in unrestrained, lower level primitive behaviors like aggression and sexuality.
• Understanding relationship between brain and behaviors have been largely influenced by improvements in research methods, like positron emission tomography (PET), or functional magnetic resonance imaging (fMRI).
  • Now we can guess a person's gender just by looking at the brain image while thinking of a person!
    

2. How is the nervous system organized?

• The nervous system can be divided into two major components: the central and the peripheral nervous systems.

• Central Nervous System (CNS): Brain and backbone.

  • one continuous unit of system.
  • protected by bone.

• Peripheral Nervous System (PNS): branched out of central nervous system.

  • Not protected by bone.

  

3. What are the Structures and Functions of the Central Nervous System?

• Spine vs Spinal cord:
  • Spine is a bone column that surrounds the spinal cord.
  • Spinal cord is a long cylinder of neural tissue extending from medulla of the brain down to the middle of the back; part of the CNS.
  • The adult spinal cord is shorter than your spine.
• Protections:
  • Bones: Skull and spinal vertebrae.
  • Meninges: membranes. If infected, suffer meningitis.
  • Cerebrospinal Fluid (CSF): Flow through outer spaces of skull and spinal cord.
    • Stored in ventricles.
    • Provides cushioning that limits damages from minor concussions.
    • Also makes the brain float to prevent wrong signaling caused by heavy neurons pressing down on others.

3-1. The Spinal Cord, Brainstem, and Cerebellum

Spinal Cord

• The spinal cord acts as a conduit for information flowing along with many sensory fibers.

• 31 pairs of spinal nerves exit out of spinal cord and brings sensory information back to the CNS and carry motor commands to muscles.
• Many important reflexes are initiated by spinal cord without any assistance from the brain.
  • Knee-jerk reflex & 3 types of neurons:
    • Sensory neurons tell the spinal cord the muscle has been stretched by the tap of the hammer.
    • Motor neurons carry commands from the CNS back to muscles.
    • Inter neurons are not used for this specific reflex, but it is importantly used in other reflexes.

Brainstem

Structure of brainstem

• 3 bulges of brain in 4th week of gestational weeks:
  • forebrain: 2 large cerebral hemispheres.
  • Hindbrain (medulla, pons, cerebellum) + midbrain = brainstem (does not include cerebellum, but is connected with it)
    • Medulla: contains nerve fibers from and to brain.
      • manages life-essential functions like breathing, heart rate, and blood pressure.
    • Pons: Management of sleep, arousal, and facial expressions
      • Pons means "bridge" in latin,
      • Bridges between higher and lower parts of the brain, as well as cerebellum to the rest of the brain.
    • midbrain:
      • sensory reflexes, movement, and pain.
      • periaqueductal gray contains receptors for endorphins, which reduces pain by decreasing the strength of pain messages traveling to higher levels of the brain.
  • Cerebellum: Maintains balance and motor coordination.
    • First structures to be affected by alcohol.
    • Contains more nerve cells than the rest of the brain combined.
    • Today's neuroscientists believe it is associated with making mental and motor skills more automatic.
  • Reticular Formation: management of levels of arousal.
    • Quick firing of cells: awake
    • Slow: sleep, or unconscious.

3-2. Subcortical Structures

Thalamus

• Gateway to cortex
• sensory systems travel first to thalamus, then thalamus forwards information to cerebral cortex.
• Involved with memory (just like hippocampus...!) and states of consciousness ().
• Lesions can lead to major memory losses.
  

Tha Basal Ganglia

• Curves around Thalamus.
• Associated with voluntary movement systems.
  • coordinate movement in response to emotional stimuli
• Lesions in basal ganglia results in not being able to identify disgusted facial expression.
• Degeneration can lead to Parkinson's disease

Hypothalamus

• motivation and homeostasis (regulation of body functions such as temperature, thirst, hunger, biological rhythms, and sexual activities)
• "4F" behaviors: feeding, fleeing, fighting, fornication (sex)
• Directs the autonomic nervous system and the endocrine systems and its hormones.

The Hippocampus

• (seahorse)
• Formation and retrieval of long term memories.
• intelligence, personality, or memories formed before its damage remain intact.
• manages stress (less effective when going through major depressive orders)

The Cingulate Cortex

• Activated when going through physical pain as well as negative feelings.

• Anterior cingulate cortex (ACC):

  • control of autonomic nervous system
  • Decision making, emotion, anticipation of reward, and empathy
  • Offenders with low activity in the ACC has twice the risk of reoffending.

• Posterior cingulate cortex (PCC):

  • memory and visual processing

Amygdala

• "almond"
• Significant in remembering, responding, and identifying fear & aggression.
• receives sensory information from the thalamus and produces emotional and motivational output that is sent to cerebral cortex.
• Salient or relevant stimuli regardless of whether they are positive or negative.
• Social behavior, emotion, and learning about reward.
  • Even a blind man's amygdala was activated when he was shown a picture of an angry face.
  • Patient named S.M. had difficulties identifying fear expressions with damaged Amygdala.

The Nucleus Accumbens

• reward and pleasure circuitry
• addiction
• Happy scene observation:
  • When people with strong connections view a happy scene, their Nucleus Accumbens are active,
  • For weaker connections people, less active.
    

3-3. The Cerebral Cortex

• Corpus callosum: nerve fiber that connects two hemispheres
• Cerebral cortex: thin layer of neurons covering the outer surface of the cerebral hemispheres.
• Lobes exist both in right and left hemispheres (pairs).
• Frontal Lobe: The most forward of the four lobes of the cerebral cortex; location of the primary motor cortex and areas responsible for some of the most complex cognitive processes.
• Parietal Lobe: cortex that lies at the top of the brain between the frontal and the occipital lobes; location of the primary somatosensory cortex.
• occipital lobe: The lobe of the cerebral cortex located at the back of the brain; location of the primary visual cortex.
• temporal lobe: The lobe of the cerebral cortex that curves around the side of each hemisphere; location of the primary auditory cortex.

Localisation of Functions in the Cerebral Cortex

• 3 functions: Sensory, motor, and association.

• Sensory cortex:

  • vision: occipital lobe (back of head),
  • hearing: temporal lobe
  • somatosensory (soma means body): parietal lobe - processes information of touch, pain (same as midbrain..!), etc.

• Motor cortex:

  • rear most frontal lobe
  • voluntary control over movement

• Association cortex:

  • Bridges between sensation, action, and abstract thought.

  

Frontal Lobe

• Primary motor cortex & cognitive functions.
  • Primary motor cortex == Basal Ganglia == voluntary movements.
• Broca's area: production of speech.
  • damage can lead to difficulty in speaking, though comprehension of speech remains good.
• Prefrontal cortex:
  • Most forward part of frontal lobes.
  • planning of behavior, attention, and judgment.
• Alien hand syndrome:
  • Happens when connections between the prefrontal cortex and lower parts of the brain involved in movement are damaged.
  • Unaware of their hands' movements.
• Phineas Gage (railroad worker):
  • Damaged frontal lobe,
  • prone to angry outbursts and unreliability.
• orbitofrontal cortex:
  • emotional lives & impulse control
  • Make us feel the shame for doing the wrong thing, thus influences decision making immensely.
  • damage can lead to deficits in social behavior and experience of emotion,
  • fail to anitipate emotional consequences, unable to delay gratification.
    

Occipital Lobe

• Visual cortex.
• Connects with temporal lobe to recognize objects.
• Connects with parietal lobe to process the movement of objects.

Temporal Lobe

• Primary auditory cortex.
• Processes higher visual system tasks:
  • recognizing objects or faces of familiar people.
• Wernicke's area: damage to it makes speaking no sense.

Parietal Lobe

• Primary somatosensory cortex - helps localise touch, pain, skin temperature, and body position
• Help better understand where our body is in time and space.
• Damage can lead to negative syndrome which causes difficulty paying attention to the space opposite to the damaged side.
• coordinates vision and movement.
  • damaged parietal lobe can lead to difficulties while inserting a card to a reader.

Mirror Neurons

• Monkeys have "mirror neurons" that help that notice the intentions of certain actions.
• Humans seem to have "mirror systems" that act the similar way.

Right Brain and Left Brain

• There are many functions of the brain that are lateralized (localised on one side of the brain)
• Split-brain operation: Cutting the corpus callosum resulted in reducing or eliminating seizures (Then why the hell does it exist??)
• Left:
  • Movement and sensation of right side of the body
  • right half of the visual field
  • mathematical computation and logical reasoning (for most ppl, others are right or both)
• Right:
  • Movement and sensation of left side of the body
  • left half of the visual field
  • language (again not for every person)
  • emotional behaviors

Right-Left Brain Myths

• "learning to access" one side of the brain to improve cetain talents does not hold up in labs.
• Hemisphere dominance - as measured by relative sizes of hemispheres and localization of language and handedness - does not predict any talent or occupational choice.

The Function of Lateralization

• Lateralization might provide organisms with ability to multitask.
  • Chicks raised in dark do not lateralize normally. They also cannot multitask, which put them in risks while feeding and watching for predators simultaneously.
• Human lateralization might have made language possible.
  • People with schizophrenia show abnormal laterlization and are more likely to be left-handed or ambiguous

4. The Peripheral Nervous System (PNS) and the Endocrine System

• The systems coordinate to to produce consistent patterns of movement, hormone release, and arousal.
• 2 types of PNS:
  • Somatic Nervous System (everything except for brain and spinal cord )
  • Autonomic Nervous System
• Endocrine System

The Somatic Nervous System

• Transmits commands from CNS for voluntary movements to the muscles.
• Brings sensory information back to CNS for further processing.
• Carried out by 31 pairs of spinal nerves and 12 pairs of cranial (head, neck, and some internal organs) nerves.

The Autonomic Nervous System

• function: Control of glands and organs tissues.
• Cruise control, because it keeps my heart beating and lung inhaling and exhaling without conscious direction.
• 3 subdivisions:
  • the sympathetic
  • the parasympathetic
  • the enteric?

Sympathetic nervous system

• prepares body for situations requiring expenditure of energy.
• A close call on a highway can result in our hearts racing, breathing rapidly, faces becoming pale, and other activities to provide muscles with the resources in a fight-or-flight situation.

Parasympathetic nervous system

• Storage of energy
• at time of relative calm.
• Store nutrients, repair body, return the activities of internal organs to baseline levels.

Enteric nervous system

• Consists of nerve cells embedded in the lining of the gastrointestinal system
• Communicates with the endocrine system to ensure the release of chemicals essential to digestion
• Some functions of enteric system lead to conscious perception (gastrointestinal pain, hunger, satiety), while others operate below the threshold of conscious awareness.

The Endocrine System

• Made up of glands that release chemical messengers known as hormones into the blood
• Hormones affect more distant cells in a coordinated fashion.
• Involved with arousal, metabolism, growth, and sex.
• Glands:

pineal gland

• melatonin: maintenance of sleep-wake cycle.
• breaks down in the presence of light,
• so no artificial light before sleep recommended.

pituitary gland

• Body's master gland.
• Oxytocin, vasopressin, human growth hormone.
• influences the release of other glands,
  • pituitary hormones control the production and release of sex hormones by the ovaries and testes.
  • thyroid gland, in response to pituitary gland, lowers or increases metabolism rate.
  • adrenal gland activated by pituitary to release other hormones (like cortisol) to provide wake-up message
• When amygdala receives danger inputs, it starts a hormonal cascades - pituitary gland and adrenal gland.

islets of Langerhans?

• Digestion hormone, like insulin.
  

5. How do neurons communicate?

• There are 86 billion neurons in human brains.
• Gila: Nervous system cells that perform a variety of support functions, including formation of the blood–brain barrier and myelin.

5-1. Neurons and Gila

• Neuron has large central mass, or cell body.
• Nucleus within cell body.
• Translation of genetic codes into manufacture of proteins happens in the cell body.
• Membranes are composed of fatty materials that do not dissolve in water, so to separate the extraceullular and intracellular fluids.
• Pores within the membranes allow chemicals to move in and out.
• Axons are responsible for carrying information to other neurons,
• Dendrites receive input from other neurons.
• Many dendrites, one axon.
• White matter: axons (insulation repells chemicals for keeping the brain for study from being absorbed).
• Gray matter: cell bodies (absorbed chemicals that makes its color pink-gray)
  

Gila

• Gila make it possible for neurons to do their job effectively.
• Some gila provide a structural matrix for neurons (like the picture above) to ensure that the neurons stay in place.
• Other gila are mobile and they clean up the debris of damaged neurons.
• Tight connections with blood vessels serving the nervous system.
  • This connection forms blood-brain barrier and prevents many toxins in the blood from exiting into brain where neurons can be harmed.
    

Myelin

• insulating material covering some axons.
• speeds up transmission of neural signals
• quicker recovery between signals
• Myelin in the CNS and the PNS react differently to nerve damage:
  • Gila in the CNS form scar tissue, which inhibits repair to damaged nerves - permanent damage.
  • PNS do not form scar tissue: help the damaged axons regrow.

5-2. Neural Signaling

• 2 step process:
  1. Neuron generates an electrical signal known as action potential.
  2. The action potential travels to the axon terminal and signals the release of chemical messangers that float across extracellular fluid separating two neurons.
  • these chemical messangers influence the likelihood of second neuron responding to the action potential - sending message along.

Electrical Signaling

• Squid has large axons that are even visible to naked eyes, which helps demonstrating the production of action potential.
• resting potential: the difference between the readings of electrodes inside of the axon and the external fluid.
  • Inside is more negatively charged than outside.
• neurons become depolarized when:
  • Electrical charges of the extracellular and intracellular recordings decrease,
  • Meaning they do not attract each other,
  • Meaning neurons will be closer to each other rather than being attracted outwards.
• neurons become hyperpolarized (being farther away) when the opposite happens.
  

1. When a neuron is depolarized by sufficient input, the threshold for producing an action potential is reached.
2. Reaching the threshold opens the channels, causing the positively charged sodium ion into the neuron.
3. The interior is more positively charged than the exterior now.
4. Potassium ion begins to leave the cell.
5. Becoming negatively charged again
6. Refractory period: no producing another action potential.
7. Propagates (duplicates the electrical signal) through axon to the terminal

Propagation:

• Way faster in myelinated axons:
  • Propagation skips the myelinated segments.
  • Action potentials are only formed between myelinated segments - these parts are known as nodes of Ranvier.
• Less energy required in myelinated axons:
  • more action potentials -> more energy expended returning the cell to its original state.