biological bases

Cortex structural features

• Gray matter

• 4 main lobes: frontal, parietal, temporal, occipital

• characterized by gyri & sulk

Frontal lobe core functions

• Executive function, impulse control, planning, personality,& motor cortex

Frontal lobe’s Executive function responsible for:

• Planning, organizing, problem-solving, decision-making, working memory.

• “filter, foresight, & follow through”

• EPPP cue: Problems w/ it can cause “difficulty planning” “poor organization”

Frontal lobe’s Impulse control responsible for:

• Inhibition of inappropriate behavior, delayed gratification, socially appropriate responses.

Frontal lobe’s Planning responsible for

• Goal setting/goal-directed behavior, sequencing steps, anticipating consequences.

Frontal lobe’s personality responsible for:

• Social judgment, emotional regulation, motivation, initiative

• EPPP cue: problems w/ it cause “ personality change” “apathy,” “ socially inappropriate”

Frontal lobe damage

• Can cause disinhibition (inappropriate social behavior), impulsivity, poor judgment, &/or personality change

Parietal lobe functions

• Sensory processing, spatial awareness, integration of sensory input (perception & position)

Somatosensory cortex

• Located in parietal lobe

• Responsible for touch, pain, temperature, & proprioception (subconscious sense of body’s position & movement; provides essential input)

• EPPP cue: problems w/ it cause: “ loss of sensation,” “ numbness”

Spatial processing

• Parietal lobe function

• Includes body awareness, orientation in space

• Conscious understanding of your body’s location, relative to the environment & objects around you

• EPPP cue: problems w/ it cause: “getting lost” & “misjudge distance”

Parietal lobe damage

• Sensory neglect (ignores one side of the body/space

  • Damage to the right one usually causes left side neglect

• Sensory deficits (impaired touch or proprioception)

Temporal lobe functions

• Memory, auditory processing, language comprehension, emotion, & facial recognition

Auditory cortex

• Located in temporal lobe

• Responsible for sound processing

Language comprehension

• Temporal lobe function

  • Wernicke’s Area

Wernicke's area

• understanding spoken/written words & producing meaningful speech

Wernicke’s Aphasia

• Fluent but nonsensical speech

• poor comprehension

location of Wernicke’s Area

• Left Temporal lobe

location of Hippocampus

• Medial temporal lobe

Hippocampus functions

• memory formation (especially converting short-term to long-term) & crucial for organizing and storing memories,

• spatial navigation, acting like the brain's GPS

• heavily influences learning, emotions, and decision-making by linking experiences, facts, and places to form new memories.

  • vital for episodic (life events) memory

  • semantic (facts) memory

  • helps create the cognitive maps needed to find your way around (aiding spatial awareness)

Damage to hippocampus

• Anterograde amnesia; difficulty forming new memories and may also affect older memories.

• Mood changes/emotional dysregulation

• Seizures, learning difficulties, spatial awareness challenges, & more.

Amygdala responsible for

• Emotional learning

• Processing emotions (especially fear)

• "fight-or-flight" response,

• Memory formation (linking emotions to memories),

• Decision-making

• Vigilance

• Social cognition

  • recognizing facial expressions

  • interpreting social signals.

Temporal lobe damage causes:

• Memory impairment (inability to form new memories)

• Wernicke's Aphasia

• Auditory processing challenges

• Mood changes, personality shifts, anxiety

• Problems with object/face recognition (visual agnosia, prosopagnosia)

Functions of occipital lobe

• Visual processing

  • interpreting color, form, and motion

  • allowing for object and face recognition

  • depth perception

  • visuospatial processing

Function of Visual cortex

• Processing visual info

  • features like color, shape, & motion

Occipital lobe damage causes

• Visual deficits

  • blindness

  • visual field cuts

  • difficulty recognizing objects

What Amygdala does

• Attaches emotional significance to stimuli → conditions fear responses

  • It is the body’s alarm system

Damage to amygdala causes

• Reduced fear; emotional blunting; poor threat recognition

Amygdala overactivity associated with:

• Anxiety; PTSD; phobias

Amygdala located

• Medial Temporal lobe

Disorders associated with hippocampus damage

• Alzheimer’s disease (early involvement)

• PTSD (memory contextualization → flashbacks)

• Epilepsy

• Depression

• Anxiety disorders

• Vascular dementia

• Schizophrenia

• Stroke

Memory contextualization

• Ability to link a memory with its specific time, place, and circumstances.

• In those with PTSD, it’s often impaired, leading to intrusive flashbacks where the trauma feels real and present rather than past event

• Primary structures responsible for it: hippocampus & Prefrontal Cortex (PFC)

Core functions of basal ganglia

• Movement regulation

  • action selection, initiation, and inhibition

    • acting as a "gatekeeper" for voluntary movement

    • filtering motor signals and facilitating smooth, purposeful behaviors. They select intended actions, suppress unwanted movements,

• Crucial roles in learning, cognition, emotion, and reward

  • learn habits, and influence decision-making

Basal ganglia damage causes

• movement disorders

  • tremors, tics, rigidity

• cognitive problems

  • OCD, attention issues

  • by disrupting the brain's control over voluntary movement, emotion, and executive functions

basal ganglia disorders

• Parkinson’s disease (decreased dopamine)

• Huntington’s disease (neurodegeneration)

• Dystonia:

  • Involuntary muscle contractions leading to twisting, repetitive movements, and abnormal postures

• Tourette's Syndrome

Core functions of the brain stem

• Basic life structures; arousal; consciousness; vital reflexes

  • stay alive and stay awake

Brain stem controls:

• Breathing, heart rate, blood pressure, sleep wake cycle

Reticular Activating System (RAS)

• Controls alertness & consciousness

  • Receives input from all sensory systems (except smell), filters sensory input, & decides what reaches conscious awareness

Location of Reticular Activating System (RAS)

• primarily in the brainstem, extending from the medulla, through the pons, and into the midbrain

• with projections to the thalamus, hypothalamus, and cerebral cortex,

Damage to Reticular Activating System can cause:

• coma, persistent vegetative states,

• severe impairment of arousal

  • hypersomnolence (excessive sleepiness), drowsiness, and altered sensorium (difficulty interpreting sensory stimuli)

• problems with focus, filtering stimuli, and the sleep-wake cycle

Brainstem damage can cause:

• Loss of consciousness; coma; death (in severe cases)

Core functions of cerebellum

• Coordination of voluntary movement; maintaining posture and balance; timing; regulating muscle tone, and enabling motor learning

  • fine-tuning the body's movements to be smooth and precise. It

• coordination and calibration

  • Does NOT initiate movement; does NOT Control strength

Cerebellar damage can cause:

• ataxia (uncoordinated, clumsy movements, poor balance, unsteady gait)

• tremors (especially when reaching)

• speech issues (slurred, slow, or uneven speech),

• eye movement problems (like nystagmus or blurry vision).

• It also affects motor skills, muscle tone

• Can lead to cognitive and emotional difficulties

  • impacting planning, memory, attention, and mood

Ataxia

• Poor muscle control, causing clumsy, uncoordinated movements affecting balance, walking, speech, and fine motor skills

• often due to damage to the cerebellum, but also other parts of the nervous system.

• Can be symptom of another condition (stroke, MS, alcohol misuse)

Impact alcohol has on the cerebellum

• poor balance, slurred speech, and jerky movements (ataxia)

location of the thalamus

• Subcortical structure; sits deep in the brain

• in between the cerebral hemispheres

  • acts as relay station to the cortex

Thalamus functions

• relay station

  • processing and transmitting sensory info (sight, sound, touch, taste), motor signals, & limbic (emotional) information to the cerebral cortex for interpretation and response

• regulating consciousness, alertness, sleep, and attention

Damage to the thalamus can cause:

• sensory deficits (numbness, confusion); altered consciousness; attention problems, memory loss, aphasia (speech/language issues), sleep disorders, vision problems, chronic pain, and motor impairments

  • severe cases potentially leading to coma

• EPPP Classic Example: “patient has difficulty processing sensory information despite intact sensory organs”

Core functions of the hypothalamus

• acts as the body's smart control center,

  • maintaining homeostasis by regulating vital functions like body temperature, hunger, thirst, sleep cycles, blood pressure, and stress responses

• links the nervous system to the endocrine system via hormone production (like ADH, oxytocin, CRH) and direct influence on the ANS.

• Controls emotions, arousal/drive, and coordinates the pituitary gland's hormone release (influencing growth, metabolism, and reproduction)

Hypothalamus regulates

• body temperature, hunger, thirst, sleep (circadian rhythms), mood, heart rate

• The release of hormones

  • by controlling the pituitary gland → managing stress response (HPA axis), growth, metabolism, reproduction, and fluid balance

Hormonal control

• Function of the hypothalamus

• which controls the pituitary gland;

  • which influences cortisol, growth hormone, & sex hormones

Hypothalamus damage can cause

• hormonal imbalances, temperature dysregulation, severe thirst (diabetes insipidus), appetite changes leading to obesity or weight loss, sleep disturbances, fatigue, blood pressure problems, delayed puberty, infertility, sexual dysfunction, & seizures

Pituitary gland core functions

• Release hormones that regulate other endocrine glands; “master gland”

  • growth ((GH, or somatotropin)

  • metabolism (thyroid-stimulating hormone) reproduction

  • stress response (ACTH; Adrenocorticotropic Hormone)

  • water balance (Antidiuretic Hormone (ADH); vasopressin)

Pituitary dysfunction can cause:

• Growth abnormalities (enlarged hands/feet)

• hormonal imbalances (menstrual irregularities, low libido, problems w/ reproduction)

• metabolic issues (weight changes)

• headaches; vision problems

• problem w/ stress response; fatigue; mood swings

Primary functions of Dopamine

• motivation, reward, movement, and cognition/attention,

  • acts as a chemical messenger that reinforces pleasurable behaviors

  • drives goal-directed action

  • influences learning, mood, attention, and memory

Disorders & behaviors associated with a decrease in dopamine

• movement disorders

  • Parkinson's Disease, Restless Leg Syndrome (RLS), Dystonia (involuntary muscle contractions)

• mood and attention issues

  • Depression, ADHD, and symptoms in Schizophrenia

    • often leading to lack of motivation, pleasure (anhedonia), focus problems, and fatigue.

• Addiction withdrawal, & potentially disruptions in sleep and memory

• tardive dyskinesia stems from blocked _____ receptors

• imbalances linked to depression, anxiety, and GI issues

Disorders & behaviors associated with an in dopamine

• Schizophrenia

  • positive symptoms: hallucinations & paranoia

• Symptoms of ADHD & addiction

• Can lead to euphoria, impulsivity, aggression, & poor impulse control

Activities that trigger an influx in dopamine

• eating, sex, music, exercise, “using substances”

Significant increase in dopamine associated with

• addictive behaviors, impulsivity, euphoria, aggression, and potentially psychosis,

  • triggered by natural rewards (food, sex, music) or drugs (cocaine, amphetamines, alcohol) that stimulate the reward pathway

Impact antipsychotics have on dopamine

• blocks dopamine D2 receptors → preventing dopamine from activating receptors

  • Dopamine antagonists

Dopamine antagonists used to

• Reduce excessive brain activity

  • for schizophrenia and bipolar disorder

• Manage certain movement disorders by stopping it from activating brain cells

Extrapyramidal Symptoms (EPS)

• Dopamine related movement disorder, which involves involuntary movement issues (like spasms restlessness, tremors, or slow movements)

Primary functions of Serotonin (5-HT)

• Regulates mood, sleep, appetite, and cognition/impulse control

• Controls gut motility, blood clotting, bone health, and sexual desire, acting as a neurotransmitter

• As a hormone it affects mood, learning, memory, and body functions (e.g., digestion, temperature, and wound healing)

Disorders and behaviors associated with a decrease in serotonin:

• mood disorders

  • depression, anxiety, OCD,

• sleep problems, digestive issues (like IBS), chronic pain, aggression, impulsivity, and cognitive decline, (affecting emotional stability, appetite, and energy levels)

• Research continues to explore its role in PTSD or autism. 

Serotonin medication link

• SSRIs increase it by blocking the reabsorption (reuptake)

Norepinephrine (NE) primary functions

• Alertness, arousal, attention, stress response

• Mobilize the brain and body for action

  • boosts alertness, attention, and arousal, especially during stress (fight-or-flight)

• Plays a role in mood, memory formation, and regulating cardiovascular functions (e.g., heart rate, blood pressure).

• Acts as a neurotransmitter in the brain and a hormone

  • enhancing vigilance, focus, and energy mobilization for challenging situations

Disorders & behaviors associated with a decrease in norepinephrine:

• Depression, fatigue, poor focus (ADHD symptoms), memory issues, low energy, anxiety, and hypotension

  • resulting from underactivity in the alertness/arousal system, often seen in chronic stress, Parkinson's, or Alzheimer's, causing lethargy and lack of motivation

Disorders & behaviors associated with an increase in norepinephrine

• Anxiety, heightened alertness, irritability, insomnia, panic attacks, high blood pressure, rapid heart rate, and hyperactivity

• often seen in conditions like ADHD, mood disorders (mania in bipolar disorder), PTSD

• Can cause physical symptoms like sweating, headaches, and jitters, reflecting its role in the "fight-or-flight" response

Functions of SNRIs

• increasing levels of serotonin and norepinephrine, and sometimes even dopamine

  • by blocking their reabsorption

Acetylcholine (ACh) primary functions

• Muscle contraction (voluntary & involuntary)

• Learning

• Memory

• functions of the ANS

  • heart rate, blood pressure, digestion, and glandular secretions

• influences attention, arousal, and immune responses.

• controlling bodily processes by acting as a chemical messenger in the CNS & PNS (nerve endings)

  • from blinking to breathing

Disorders & behaviors associated with a decrease in acetylcholine:

• strongly linked to Alzheimer's disease

  • causing memory loss, confusion, and attention issues

• plays a role in:

  • Parkinson's disease (imbalance with dopamine)

  • myasthenia gravis (receptor issues) and delirium,

  • impacting learning, memory, focus, and muscle control

• potentially contributing to apathy

Disorders & behaviors associated with an increase in acetylcholine

• cholinergic crisis

  • leading to excessive muscle contractions/twitches, paralysis, slow heart rate, breathing issues, salivation, tears, nausea, diarrhea, blurred vision, and potentially seizures or coma,

• Can induce or worsen depression, anxiety, and psychotic symptoms

  • affecting attention and emotional regulation

Functions of GABA neurotransmitter

• Primary inhibitory neurotransmitter

  • nervous system's brakes to calm nerve activity, reduce excitability, and control the speed of information flow between neurons

  • leading to calming effects that help manage anxiety, stress, and fear.

• Decreases neuronal firing, preventing neurons from sending signals and keeping the nervous system from becoming overstimulated or overwhelmed

Disorders & behaviors associated with low GABA levels

• Increase in Anxiety, panic attacks

• mood disorders (depression, bipolar), epilepsy/seizures, ADHD, autism spectrum disorder, PTSD, and schizophrenia,

• Manifests as heightened stress, irritability, poor sleep, and difficulty regulating emotions

• aggressiveness and hyperactivity.

Disorders & behaviors associated with high GABA levels

• Increased inhibition in the brain

  • Linked to sedation, drowsiness, reduced anxiety, and slowed neural activity

• Imbalances are implicated in anxiety, depression, autism, epilepsy, and sleep disorders

Benzodiazepine’s impact on neurotransmitters

• Enhances GABA (gamma-aminobutyric acid; main inhibitory neurotransmitter)

  • it binds to GABA-A receptors → chloride ions enter neurons → slows down nerve activity → producing calming, sedative, and anxiety-reducing effects on the CNS

Glutamate primary function

• Primary excitatory neurotransmitter

• crucial for fast nerve signal transmission, learning, memory (synaptic plasticity), cognition, and mood.

• It excites neurons → more likely to fire & balances with GABA (inhibitory) → controls overall brain activity.

• Vital for metabolism, energy, waste removal (urea), and regulating sleep cycles, & an energy source in the brain when glucose is low

Disorders & behaviors associated with high levels of glutamate:

• Excitotoxicity

  • Overexcites neurons, damaging them and disrupting brain function → seizures

  • Leading to behaviors and disorders like anxiety, restlessness, poor focus, depression, & OCD

• Potentially worsening neurodegenerative diseases (Alzheimer's, Parkinson's, ALS)

• Contributing to symptoms in autism, schizophrenia, stroke, and chronic pain.

• Imbalances can manifest as being easily overwhelmed, disorganized attention, or a restless mind, affecting mood, cognition, and impulse control,

Disorders & behaviors associated with low levels of glutamate:

• Linked to Depression

  • causing low mood, fatigue, insomnia, and poor concentration, and are

• Also implicated in schizophrenia, ASD & ADHD

  • contributing to cognitive deficits, anxiety, and social impairments, with research pointing to dysregulation in mood and cognitive areas.

Neurotoxicity

• Damage to the nervous system from exposure to natural or neurotoxins, causing issues like confusion, weakness, memory loss, or paralysis with symptoms varying from mild to severe and potentially permanent

• Can be caused by mental health-related drugs

  • especially illicit stimulants (meth, cocaine, MDMA) and sometimes prescribed psychostimulants (like Adderall), antidepressants, antipsychotics, and dissociatives,

Central Nervous System (CNS)

Brain & spinal cord.

Damage to CNS can cause:

Cognitive impairment; personality change; sensory deficits; motor deficits

Spinal Cord

• Pathway for sensory & motor signals

• Reflexes (simple behaviors w/o cortex)

• EPPP Cue for damage to it: “reflex intact despite brain injury”

CNS’ Protective structures

Skull, vertebrae, meninges, cerebrospinal fluid

Peripheral Nervous System

• Nerves outside of the CNS (brain and spinal cord).

• Relays sensory info to CNS and motor commands to the body.

• Divided into 2 systems

  • somatic nervous system

  • autonomic nervous system

    • ANS split into 2 branches

Autonomic Nervous System (ANS)

• Regulates involuntary physiological processes

  • e.g., heart rate; blood pressure; breathing, digestion, & “arousal”

  • to maintain homeostasis.

• Split into 3 branches:

  • sympathetic (fight or flight)

  • parasympathetic (rest & digest)

  • enteric nervous systems (gastrointestinal system)

Sympathetic Nervous System

• Part of ANS.

• Triggers “fight or flight” response

  • prepping the body for stress, danger, or intense activity. I

  • increases heart rate, blood pressure, breathing rate, & pupil size, & inhibits digestion

Parasympathetic Nervous System

• Part of ANS

• Governs “rest and digest” bodily functions

  • conserving energy & maintaining homeostasis.

  • Lowers heart rate, simulate digestion, constricts pupils, & relaxes muscles.

• Primarily uses acetylcholine (ACh) for nerve transmission

Nervous vs Endocrine System

what it uses & its impact on the body

• Uses neurotransmitters yo transmit signals quickly, resulting in short-lasting effects

  • Its effects are short-lasting

• Uses hormones to regulate bodily functions with slower and longer-lasting effects.

Endocrine system

• Uses hormones (chemical messengers) to regulate behavior, mood, & mental health.

• Influences stress (cortisol), social bonding (oxytocin), sleep (melatonin), & sex drive (testosterone/estrogen).

• Bidirectional interactions between hormones & behavior:

  • hormones shape behavior & behavior can alter hormone levels, affecting personality, cognition, & emotional states.

Endocrine Dysregulation

• Can be induced from:

  • chronic stress

  • over-activating HPA axis which causes alteration in cortisol production (initially high then later low)

  • reduced cortisol receptor sensitivity (effectiveness of hormone is reduced).

• Chronic disruption of it:

  • suppresses reproductive hormones, impairs thyroid function, weakens immunity, promotes inflammation

    • leads to structural & functional brain changes → contributing to anxiety, depression, & cognitive impairment

Hypothalamic-Pituitary-Adrenal (HPA) axis

• Communication network linking hypothalamus & pituitary & endocrine glands to manage stress by releasing cortisol

  • critical to survival & homeostasis

• Hypothalamus releases CRH → signals pituitary to release ACTH →tells adrenals to produce cortisol→ affecting mood, immunity, & metabolism

• Chronic over-activation can lead to immunity problems, anxiety, & depression

Thyroid Gland

• Releases hormones to regulate metabolism, energy level, heart rate, & body temperature

• Body’s metabolic accelerator

• Controls speed:

  • if it releases too much of the hormones → speeds everything up

    • hyper____

  • if it does not release enough of the hormones→ slows everything down

    • hypo____

Hypothyroidism

Thyroid does not release enough

Too little thyroid hormone

Effects include: slowed metabolism, fatigue, weight gain, depression-like symptoms, cold intolerance, slowed thinking

Hyperthyroidism

• Thyroid releases too much hormone

  • Effects include increased metabolism, anxiety, weight loss, heat intolerance, restlessness, rapid heart rate

Hypothyroidism

• Thyroid does not release enough hormone

  • Slows your metabolism → causing fatigue, weight gain, cold intolerance, dry skin/hair, constipation, and depression

  • Impacts nearly every body system

    • heart (slowed rate, high cholesterol)

    • brain (brain fog, memory issues, nerve damage)

    • reproductive system (irregular periods).

    • Severe, untreated cases risk heart failure, nerve damage, infertility, and a dangerous coma

Structures made up of the Endocrine system

• Major glands like the Pituitary, Thyroid, Parathyroid, Adrenal, and Pineal Glands

• Hypothalamus, which links to the brain

• Pancreas, which manages blood sugar

• Gonads (ovaries and testes) for reproduction

• Kidneys, heart, and liver also have functions, producing hormones that travel through the bloodstream

Hypothalamus

• Maintains homeostasis

• links nervous system to endocrine systems

• controls pituitary

• Regulates: hunger, thirst, sex drive, temperature, stress (1st part of HPA axis)

Pituitary Gland

• “Master gland;” releases hormones that regulate other glands

• it is controlled by hypothalamus

Adrenal Glands

• body’s stress response

• releases cortisol & epinephrine

• “fight or flight”

Lateralization

• Certain cognitive functions are dominant in 1 hemisphere

• Left hemisphere excels in language, logic, and fine motor skills

• Right hemisphere handles visuospatial tasks, emotion, and holistic processing

• Key structures like the motor/somatosensory cortices, auditory cortex, and cingulate gyrus have specialized roles

  • all connected by the corpus callosum, allowing efficient processing despite both sides working together.