Neuroscience final exam study guide

Week 9

Sensory Receptors & Sensation

Ascending Pathways carry sensory info to the brain (e.g., Lateral Spinothalamic Tract).

• Thalamus processes all sensation except olfaction.

Receptor Types

• Exteroceptors: external stimuli (touch, vision, hearing).

• Interoceptors: internal stimuli (pain, pressure).

• Proprioceptors: body position, prevent overstretch.

• Cutaneous Receptors: skin—pain, temp, touch.

• Visceral Receptors: from internal organs.

Special Sense Receptors: Visual, Auditory, Olfactory, Gustatory, Equilibrium

Receptor Structures & Functions

• Mechanoreceptors: touch, pressure, vibration, proprioception

• Examples: Pacinian (vibration), Meissner (touch), Merkel (pressure), Baroreceptors (blood pressure)

• Thermoreceptors: temp (hot/cold), pain from extreme temps

• Chemoreceptors: taste (direct), smell (distance/gas)

• Photoreceptors: light (Rods: B&W, Cones: color)

Receptor Fields

• Small fields = high sensitivity (lips, hands)

• Large fields = low sensitivity (back, legs)

Homunculus: Map of body parts’ sensory representation in the brain

Developmental Classification

• Protopathic: basic touch, danger detection (hyporeactive)

• Epicritic: precise sensation (hyperreactive, sensory defensiveness)

Sensory Dysfunction & Occupational Impact

• Issues in receptors (cutaneous, proprioceptive, visual, auditory, olfactory) affect performance

• Pain disrupts engagement in tasks

Pain

• Nociceptors: detect harmful stimuli

Pain Stages:

• Transduction → Transmission (A-delta, C fibers) → Perception → Modulation

• Pain Threshold vs. Pain Tolerance

Pain Pathways

• Spinothalamic: conscious pain (skin/muscle)

• Reticulospinal: sends pain to brainstem, releases endorphins

• Trigeminothalamic: facial pain via trigeminal nerve

Pain Types

• Somatic: skin, muscle, bones

• Visceral: internal organs

• Acute: < 30 days

• Chronic: prolonged

Chronic Pain

• Prostaglandins → lower pain thresholds → Allodynia

• Leads to pain memory in spinal cord

Referred Pain: Pain felt away from origin site

Theories of Pain Control

• Gate Theory: pain blocked at spinal level (basis for future theories)

• Counterirritant Theory: non-pain input inhibits pain (e.g., rubbing area)

Pain Inhibition

• Analgesia: no pain from pain-causing stimulus

• Endorphins: natural pain blockers (enkephalins, beta-endorphins)

• Pharmaceuticals: opiates, NSAIDs, acetaminophen, muscle relaxants

Pain Management

• Invasive:Nerve Blocks, Spinal Surgery, Intrathecal Pumps

• Non-Invasive: Massage, TENS, heat/cold, acupuncture, meditation, kinesio tape

Pain Diminishment

• NSAIDs inhibit prostaglandins

• Local anesthetics block nerve endings

• Heat/cold alter circulation

Pain Intensification: Anxiety, fear, inflammation, edema increase sensitivity

Occupational Impacts of Pain

• Loss of pain: risk of unnoticed injury

• Chronic pain: limits function and participation

Fibromyalgia

• Chronic pain condition

• CNS sensitization → widespread tenderness

• Possibly linked to poor sleep or HPA axis dysfunction

Week 10

Special Senses Overview

Five Special Senses: Olfaction (smell), Gustation (taste), Vision, Audition (hearing), Equilibrium (balance)

Olfaction (Smell)

• Nerve: Olfactory (CN I)

• Pathway: Nasal membrane → Olfactory bulb/tract → Temporal lobe (olfactory cortex) → Hypothalamus → Thalamus → Orbitofrontal cortex

Functions:

• Links smell to memory/emotion (limbic system)

• Conscious odor recognition

Therapeutic Use:

• Stimulates CNS in comatose patients

• Mood enhancement via aromatherapy

Pathologies:

• Anosmia: Loss of smell (bilateral lesion)

• Seizure auras with smell hallucinations (olfactory cortex damage)

Gustation (Taste)

Nerves: CN VII (Facial), IX (Glossopharyngeal), X (Vagus)

Receptors: Taste buds on tongue papillae

Pathway: Taste buds → CN 7/9/10 → Medulla → Thalamus → Gustatory cortex (insula)

• Smell enhances taste

Therapeutic Use:

• Used in coma care

• Supports oral motor development

Vision

Nerve: Optic (CN II)

Receptor: Retina (fovea/periphery)

Pathway: Retina → Optic nerve → Chiasm → Tract → Midbrain/Thalamus → Occipital lobe

Cortex:

• Primary: Detection

• Association: Interpretation

Visual Field Mapping:

• Nasal visual field = lateral retina

• Temporal field = medial retina (crosses at chiasm)

Pathologies:

• Homonymous hemianopia: One-sided field loss

• Bitemporal hemianopia: Loss of both outer fields

• Complete chiasm damage: Total blindness

• Nystagmus: Can be normal or pathological (labyrinth, CN8, cerebellum)

Audition (Hearing)

Nerve: Vestibulocochlear (CN VIII)

Receptors: Hair cells

Pathway: Sound → Tympanic membrane → Ossicles (hammer, anvil, stirrup) → Inner ear

Pathologies:

• Sensorineural: Inner ear/CN8/brain damage

• Conductive: Outer/middle ear damage

• CN8 lesion: Deafness/tinnitus

• Auditory cortex lesion: Cortical deafness

• Association cortex lesion: Auditory agnosia

Equilibrium (Balance)

System: Vestibular (inner ear)

Nerve: Vestibulocochlear (CN VIII)

Pathway: Vestibular input → Vestibulospinal tract → Motor neurons → Antigravity muscles → Feedback to cerebellum

Connected to:

• Reticular formation (brainstem)

• Autonomic NS (via Vagus nerve)

Symptoms of Dysfunction:

• Nystagmus, vertigo, tinnitus, balance issues, falls

• Broad stance, nausea, vomiting

Week 11

Motor Function

Primary Areas of Motor Control:

• Cerebral Cortex

• Basal Ganglia

• Cerebellum

Cerebrum: Motor Areas

• Primary Motor Cortex (M1)

• Located in precentral gyrus; origin of corticospinal tract

• Plans/executes voluntary movement with other motor areas

• Lesions → contralateral voluntary movement loss

Premotor & Supplementary Motor Areas

• Premotor: anterior to M1; involved in praxis (motor planning)

• Supplementary: assists bilateral control of posture and praxis

Frontal Eye Fields: direct visual attention/saccades

Motor Planning

Ideational Praxis: understanding motor demands

Ideomotor Planning: executing the motor plan

Basal Ganglia

• Controls stereotyped, automated movements (e.g., walking, writing)

• Involved in reward, impulse control (e.g., ADHD)

• Neurotransmitters: dopamine, GABA, acetylcholine

Pathway: M1 → Basal Ganglia → Thalamus → M1/premotor

• Lesions: trouble starting/stopping movement

• Conditions: Parkinson’s, Huntington’s, Tourette’s, dystonias

Cerebellum

• Coordinates movement, tone, posture, proprioception

• Lobes & Damage Effects:

• Archicerebellum (Flocculonodular): balance/gait issues

• Paleocerebellum (Anterior): impaired precision movements

• Neocerebellum (Posterior): issues with anticipatory/cognitive motor planning

• Lesion Effects:

• Ataxia, dysmetria, disrupted reciprocal movement

Sensory Function & Dysfunction

Pathway: Sensory input → Thalamus → Postcentral gyrus (SS1)

• Damage → contralateral sensory loss

Secondary Somatosensory Cortex (SS2)

• Integrates and gives meaning to sensory input

• Lesion Effects (Perceptual Dysfunction):

• Tactile Agnosia: can't recognize by touch

• Visual Agnosia: can't recognize by sight

• Auditory Agnosia: can't recognize sounds

Week 12

PERCEPTION

Definition: Integrating sensory input into meaningful experiences.

Sensory Modes: Olfaction, gustation, tactile, auditory, visual

Multimodal Association Areas

• Posterior (parietal-occipital-temporal): Sensory perception

• Anterior (prefrontal cortex): Motor perception & planning

Limbic: Emotional perception (hippocampus, cingulate, amygdala); links sensory info to emotion/motivation

Motor Planning Terms

• Ideational praxis: Understanding motor task demands

• Ideomotor Planning I: Knowing how to implement plan

• Ideomotor Planning II: Actually performing the plan

Perceptual Impairments: Commonly due to right hemisphere damage

Visual Perception

• Visual agnosia: Can't recognize objects

• Prosopagnosia: Can't recognize faces

• Simultanagnosia: Only perceives one object at a time

• Metamorphopsia: Visual distortion

• Color agnosia/anomia: Can't recognize/name colors

Visual-Spatial Deficits

• R-L discrimination

• Figure-ground & form-constancy issues

• Depth perception, spatial orientation, topographical disorientation

Tactile Perception

• Tactile agnosia / Astereognosis: Can't recognize by touch

• Ahylognosia: Can't ID materials

• 2-point discrimination, agraphesthesia, abarognosis, atopognosia

Body Schema Disorders

• Finger agnosia, unilateral neglect, anosognosia

• Extinction of simultaneous stimulation

Language Perception (Aphasias)

• Receptive aphasia: Poor comprehension

• Expressive aphasia: Poor production

• Alexia/dyslexia: Can't read

• Agraphia: Can't write

• Acalculia: Can't calculate

• Anomia: Can't name objects

• Agrammatism, asymbolia, aprosodia

Apraxias (Motor Planning Disorders)

• Ideational: Can't select a motor plan

• Ideomotor I: Can't access motor plan

• Ideomotor II: Can't execute it

• Dressing apraxia, 2D/3D constructional apraxia

COGNITION

Definition: Mental processing (begins in the frontal lobe)

Multimodal Association Areas

• Posterior: Integrates sensory info

• Anterior (Prefrontal): Memory, planning, higher reasoning

Neural Pathway for Decision Making

• Prefrontal Cortex → Anterior Cingulate → Limbic System → Memory Centers

Levels of Cognition

• Low: Arousal, attention, memory, recognition, simple commands

• High: Insight, planning, abstraction, problem-solving, new learning, safety/judgment

Cognitive Functions & Examples

• Orientation: Time/place awareness

• Categorization: Grouping by traits

• Sequencing: Ordering steps

• Organization: Structuring tasks

• Planning/Problem-solving: Strategies, overcoming obstacles

• Self-regulation/Inhibition: Controlling emotions/impulses

• Initiation/Termination: Starting & stopping tasks appropriately

• New learning/Generalization: Acquiring & applying knowledge

• Direction following: Acting on instructions

• Abstraction: Understanding non-concrete concepts

• Insight: Self-awareness

• Judgment: Making sound decisions

• Metacognition: Thinking about thinking

• Delayed gratification: Resisting immediate rewards

• Motivation: Drive toward goals

• Mental flexibility: Adapting to change

Proprioception

Definition: The ability to sense one’s body position in space.

Systems Involved: 

Visual

• Provides environmental cues to locate the body in space.

• Visual deficits make proprioception harder due to lack of visual reference.

Vestibular

• Maintains balance and equilibrium, aiding body orientation.

Proprioceptive System

• Involves feedback/feedforward loops among: Muscle spindles, Golgi tendon organs (GTO), Joint receptors, Cerebellum

Muscle Spindles: Detect changes in muscle length.

Structure:

• Equatorial part (non-contractile): Detects stretch.

• Polar part (contractile): Adjusts spindle sensitivity.

• Fibers: Nuclear bag + Nuclear chain

Sensory Fibers:

• Type Ia (primary): Large, fast, responds to stretch.

• Type II: Medium, slower, responds to sustained length.

Gamma Motor Neurons

• Regulate spindle sensitivity.

• Gamma 1 (dynamic): Rapid response, targets nuclear bag.

• Gamma 2 (static): Slower, targets nuclear chain.

Golgi Tendon Organs (GTO)

• Located in tendons near muscle insertions.

• Detect muscle tension and prevent over-contraction.

Action: Muscle contraction → GTO activation → Muscle relaxation via inhibition.

Joint Receptors

• Detect mechanical changes in joint capsules/ligaments.

• Send info to cerebellum and spinal cord.

Types:

• Ruffini endings, Paciniform corpuscles (II fibers)

• Ligament receptors (Ib fibers)

• Free nerve endings (A and C fibers)

Week 14

Muscle Tone

Muscle Tone: Continuous, unconscious muscle contraction at rest.

• Maintains posture and joint stability.

Muscle Strength: Conscious ability to contract muscles to generate force.

Upper Motor Neurons (CNS):

• Corticospinal tract, Basal Ganglia, Brainstem centers (vestibular & reticular nuclei), Cerebellum

• Involves extrapyramidal tracts: vestibulospinal, rubrospinal, reticulospinal

• Sensory input via spinocerebellar & cuneocerebellar tracts, joint receptors, muscle spindles, GTOs

Lower Motor Neurons (PNS):

• Alpha & gamma motor neurons (ventral horn)

• Peripheral nerves to skeletal muscles

Hypotonicity: Low tone; seen in LMN lesions & posterior cerebellar damage

Hypertonicity (UMN lesions): High tone

• Spasticity: one-sided resistance

• Rigidity: bilateral resistance

• Clasp Knife: sudden release after stretch

• Cogwheel: jerky movements

• Lead Pipe: constant resistance

• Clonus: rhythmic, involuntary contractions

Causes of Spasticity

• Overactive reflexes

• Reduced antagonist inhibition

• Loss of upper motor neuron control

• M1 or brainstem damage (vestibular, reticular, pontine nuclei)

Therapeutic Techniques

• To Increase Tone (hypotonicity): Quick stretch, tapping

• To Decrease Tone (hypertonicity): Slow stretch, deep tendon pressure, splinting, serial casting

Attention

Definition: Core cognitive function influencing focus; linked to arousal and alertness.

Types:

• Sustained: Maintain attention over time (e.g., vigilance).

• Selective: Focus on specific input while ignoring others.

• Shifting (Divided): Attend to multiple tasks (e.g., cooking while talking).

Attentional Networks

Alerting

• Brain: Thalamus, frontal & parietal lobes

• NT: Norepinephrine

• Function: Reacting to new stimuli (e.g., siren)

Orienting

• Brain: Superior parietal, temporo-parietal junction, frontal eye fields

• NT: Acetylcholine

• Function: Shifting focus (e.g., turning to a speaker)

Executive Control

• Brain: Anterior cingulate, lateral prefrontal cortex

• NT: Dopamine

• Function: Planning, managing attention goals

Goal-Directed Attention

• Frontal cortex: Attention control

• Parietal cortex: Alerting

• Multimodal association areas: Integration of sensory info

Memory

Key Brain Areas:

• Limbic System: Emotions (hippocampus, amygdala)

• Basal Ganglia: Habits, movements

• Cerebellum: Motor learning

• Frontal Lobe: STM (prefrontal cortex)

• Other Lobes: Storage of object/person attributes

• Hemispheres: Right = spatial, Left = language

Memory Types

• Short-term vs. Long-term: Seconds vs. hours/days/years

• Explicit: Conscious recall

• Implicit: Unconscious memory

• Retrospective: Past recall

• Prospective: Future planning

Memory Encoding & Storage

• STM → LTM through associations (time, place, emotion)

• Fragmented storage by sensory type (sound, touch, etc.)

• Consolidation: Requires sleep

Mnemonics

• Method of loci: Visual + spatial memory

• Acronyms & Rhymes: Verbal aids

Amnesia Types

• Retrograde: Loss of past memories

• Anterograde: Can't form new memories

• Transient Global Amnesia: Temporary total memory loss

Emotion

Primary Structures: Prefrontal cortex, limbic system, anterior cingulate

Secondary: Thalamus, anterior insula, septum pellucidum

Hemispheric Differences

• Right Prefrontal: Negative emotions (anxiety, depression)

• Left Prefrontal: Positive mood, well-being

Emotion & Brain Injury

• Left PFC damage: Emotional lability, depression

• Right PFC damage: Euphoria, lack of concern

• Orbitofrontal lesion: Impulsivity, poor regulation

• Dorsolateral lesion: Apathy, low motivation

Amygdala

• Role: Threat detection, emotional cue processing

• Lesions: Reduced fear, increased risk-taking

PTSD: Overactive amygdala, reduced language function, somatic flooding

Other Disorders

• Anxiety/OCD: Anterior cingulate → amygdala → temporal cortex

• Anger: Septal area

• Depression: ↓ Prefrontal/ACG activity, ↑ amygdala/hippocampus

• Involves serotonin, norepinephrine, dopamine imbalance