HOSA BH - The Mind

Central Nervous System (CNS)

• The body’s main control center, consisting of the brain and the spinal cord. Protected by cerebrospinal fluid.

Peripheral Nervous System (PNS)

• The nerves around/separate from the CNS.

• Divided into the somatic (voluntary, e.g. movement and sensory) and autonomic (automatic, e.g. heart rate) nervous systems.

The three types of neurons are:

Sensory - information about environment or body

Motor - commands to muscles and glands

Interneurons - neither sensory nor motor, the “middle man” that connects sensory and motor pathways.

Lateralization

The division of labor between the two hemispheres of the brain, where each hemisphere has specialized functions.

• Allows for multitasking and language, but may allow for schizophrenia and ASD in extremes.

• sensation from one side of the body is processed by the opposite hemisphere

Brainstem

• Contains the midbrain, pons and medulla

• Connects the cerebrum to the spinal cord

Medulla

• Part of the brainstem

• Controls essential functions, such as heart rate, breathing and blood pressure

Pons

• part of the brainstem

• located between the medulla and the midbrain

• controls alertness, such as sleep, arousal, pain signals and facial expressions

Cerebrum

• divided into four lobes

• split into two hemispheres connected by the corpus callosum

Corpus callosum

• a band of nerve fibres

• connects the right and left hemispheres of the cerebrum

cerebral cortex

• the outer layer of neural tissue in the cerebrum

• performs localized functions

Parietal lobe

• top of the brain, behind the frontal lobe

• processes sensory information, especially touch, pain and temperature (somatosensory cortex)

temporal lobe

• located above the brainstem

• processes auditory information (auditory cortex), language comprehension (Wernicke’s area) and memory

• contains the amygdala

Occipital lobe

• back of the brain

• processes visual information, such as colour, shape, depth perception (visual cortex)

Frontal lobe

• the largest lobe, by the forehead

• controls complex stuff, such as decision making, impulsivity, problem solving and speech/language (Broca’s area)

• Not fully developed until mid 20s

Limbic system *sub-colour

• located beneath the temporal lobe

• contains a set of subcortical structures, including the amygdala and nucleus accumbens

• performs a variety of functions related to memory, emotion, behaviour and smell

nucleus accumbens

• the “reward center”

• processes pleasure, motivation, reward

• implicated in addiction, anxiety, depression and OCD

• part of the limbic system

amygdala

• processes emotional responses and decision-making

• part of the limbic system

cingulate cortex

• above the corpus callosum

• processes emotions and connects the right and left of the cerebrum

• part of the limbic system

hippocampus

• responsible for long-term memory formation and spatial navigation

• impacted by alzheimer’s

• part of the limbic system

Hypothalamus

• located below the thalamus

• the body’s main regulator of homeostasis

• controls thirst, hunger, temperature, sexual behaviour and aggression

• part of the limbic system

Basal ganglia

• a collection of subcortical structures

• voluntary movement control

• affected by Parkinson’s

• part of the limbic system

Thalamus

• a subcortical structure

• located above the brainstem

• relays sensory and movement information, and regulates alertness

• part of the limbic system

Cerebellum

• the “little brain”

• located behind the brainstem at the back of your head

• controls balance, posture, coordination and motor learning

Endocrine system

The system of glands and organs that produce/secrete hormones.

Pineal gland

• produces melatonin, regulates sleep/wake cycles

Pituitary gland

• master gland, controls the other glands in the endocrine system

• also releases/triggers release of growth hormones, sex hormones, and social/behavioural hormones (oxytocin and vasopressin)

Adrenal glands

• Release cortisol and adrenaline

Thyroid gland

• regulates growth and metabolism

• can cause similar symptoms to depression if not working properly

Islets of Langerhans

• Release insulin for digestion

• when attacked by T-cells, causes T1D

Explain this

Reuptake

The process in which a neurotransmitter in the synapse is recycled to the axon it was released from

Acetycholine

• a neurotransmitter crucial for learning, memory and movement

• Alzheimer’s causes a deficiency of this

Norepinephrine

• a neurotransmitter that controls arousal and fight-or-flight

• elevated in BP mania and PTSD

Dopamine

• a neurotransmitter that regulates reward, motivation and movement

• lower levels in ADHD and Parkinson’s, higher in schizophrenia

Serotonin

• a neurotransmitter that regulates happiness, sleep and appetite

• lower levels in depression and anxiety, sleep issues

Endorphins

• neurotransmitters that help with pain relief and mood boosting after stress or pain

• deficiencies associated with depression and anxiety,

Transduction

When sensory information is turned into neural signals

Sensory adaptation vs selective attention

sensory adaptation - ignoring non-changing stimuli (background noise) in favour of changing stimuli

selective attention - prioritizing specific stimuli

Bottom-up vs top-down processing

bottom up - building perceptions from simple input

top down - using prior knowledge/memories to interpret input

absolute threshold vs difference threshold

absolute - the smallest detectable amount of stimulus

difference - the smallest detectable different between two stimuli

Signal detection & four outcomes

Separating certain stimuli from background noise

Hit - stimuli present and correctly detected

Correct rejection - stimuli present but not detected

Miss - stimuli not present and not detected

False alarm - stimuli not present but accidentally detected

Information processing continuum

The three steps of memory: encoding, storage and retrieval

Types/stages of memory *e.g. short-term

Sensory - incoming sensory information, very brief memory (a few seconds)

Short-term memory - small amount of information for a short time, includes working memory (information in active use)

Long-term memory - large amounts of information held for a long time

Types of long term memory

semantic - general knowledge

episodic - personal history

autobiographical - combination of semantic and episodic relating to the self

procedural - skills/abilities

memory decay vs interference

decay - harder to access memories that haven’t been used recently

interference - harder to access memories due to competition with other memories, either more recent or older

Classical vs Operant conditioning

Classical - Pavlov’s dogs - associating two stimuli to produce an involuntary response

Operant conditioning - Skinner box - associating a behaviour with punishment or reward to elicit or eliminate the behaviour

James-Lange theory

A theory that emotions occur after the body’s physical reactions to stimuli, as a response to the reaction

Stimuli → physical reaction → interpretation → emotion

Cannon-Bard theory

A theory that emotions and the body’s physical reactions to stimuli occur at the same time

Stimuli → physical reaction + emotion

Schacter-singer theory

A theory that the body’s physical reactions to stimuli work in combination with the brain’s assessment of the stimuli to produce emotions, based on cues and past experiences

Stimuli → physical reactions + assessment —> emotions

SAME model of emotion

A theory that different stimuli need different physical and cognitive processes to produce emotion. (Essentially a combination of James-Lange, Cannon-Bard and Schacter-Singer)

Leptin

A hormone that controls appetite. High leptin levels causes satiety/fullness

Default mode network

A brain network that activates when an individual is not focused on the outside world (e.g. daydreaming, self-reflecting)

What are the three waking brain waves detected by EEG?

Alpha - relaxed, 2-12 cycles per second

Beta - alert, 15-30 cycles per second

Gamma - intense focus >30 cycles per second

What are the 4 stages of N-REM sleep?

Stage 1 - unaware they are sleeping, theta waves 4-7 cycles per second

Stage 2 - may sleep through stimuli, theta waves 4-7 cycles per second

Stage 3 and 4 - deep sleep, delta waves 1-4 cycles per second

REM sleep

• the dreaming stage

• rapid eye movement and muscle twitches

• called paradoxical sleep because brain activity is like being awake

Narcolepsy vs cataplexy

Narcolepsy is daytime sleepiness + sleep attacks

Cataplexy is temporary muscle paralysis, but the person maintains consciousness

Partial vs generalized seizures

Partial starts in a specific spot of the brain, generalized starts in both hemispheres at once

Tonic-clonic vs absence seizures

Tonic-clonic - lost consciousness, violent muscle contractions, often temporary cessation of breathing

Absence - lost consciousness but aware of surroundings, blinking and eye movements instead of large contractions