Macro-anatomy

Brain

Human brains (vs animals)

  • Metabolically expensive
  • High EQ (brain size controlled for body size)
  • Cerebral cortex well developed
    => evolutionary advantage - range of intelligence

Size comparison (vs animals)

  • Absolute brain mass != intelligence
  • Encephalisation quotient: log brain mass / log body mass

Investigative techniques

Brain injury

Psychosurgery

Neuroimaging

Brain stimulation

Invasive

Non-invasive

Invasive

Non-invasive

TMS: Transcranial Magnetic Stimulation

  • Electromagnetic field to induce currents in brain
  • Use: MDD (depression)

PET: Positron Emission Tomography

  • Injected radioactive 'tracer' that binds to brain molecules
  • High spatial, poor temporal
  • Use: brain function; diagnose cancer, dementia

EEG: Electroencephalography

  • Electrodes on scalp
  • High temporal, low spatial
  • Use: evaluate brain disorders (seizure timing, narcolepsy - sleep, psychoses, Alzheimer's)

MRI: Magnetic Resonance Imaging

  • Magnetic fields to measure brain/body tissue
  • High spatial, (low temporal)
  • Use: brain structure; diagnosis (bleeding, swelling, tumours, seizures, strokes)

DBS: Deep Brain Stimulation

  • Insert electrodes in brain
  • Use: treat Parkinsons, essential tremour, MS
  • Disease

  • Injury


  • Limited: imprecise, uncontrolled

  • Animals: ablation, electrode insertion
  • Humans: lesion, DBS

fMRI: Functional MRI

  • Indirect measure - changes in blood levels - BOLD
  • Low temporal
  • Use: brain function; detect abnormalities (tumours), effect of stroke/disease

Resolution

  • Spatial: precise area
  • Temporal: how fast

Subcortical

Cerebral cortex

Frontal lobe

  • Voluntary movement
  • Personality
  • Working memory
  • Reward & punishment

Occipital lobe

  • Vision

Parietal lobe

Temporal lobe

  • Hearing
  • Object recognition & facial perception
  • Memory

Hindbrain
(Brain stem + cerebellum)

Brain stem

Pons

Midbrain

Forebrain
(Limbic system)

  • Higher order functions

Thalamus

Hypothalamus

Amygdala

Hippocampus

Basal ganglia

Cerebellum

Reticular formation

Medulla oblongata

Corpus callosum

Primary motor cortex

DPFC (dorsolateral prefrontal cortex)

Somatosensory cortex

Parietal cortex

  • Transmit (sensory) signals from spinal cord
  • Respiratory, cardiovascular
  • Reflexes: vomit, cough, sneeze, swallow
  • Neurons crossover (bridge)
  • REM sleep (inhibit movement)

Inside medulla & pons

  • Sleep & wake & arousal
  • Ascending pathway: from body -> cortices
    e.g. cats sleep / wake

Tectum

  • Vision & eye movement (superior colliculus)
  • Hearing (inferior colliculus)
    Tegmentum
  • Motor control & movement reward (substantia nigra)
  • Movement / motor control
  • Balance
  • Gait & posture
    e.g. girl with cerebellar hypoplasia
  • Gateway for sensory (except smell)
    ** Tongue -> gustatory cortex
    ** Visual -> lateral geniculate nucleus -> primary visual cortex
    ** Sound -> medial geniculate nucleus -> auditory cortex
    ** Touch/pain/pressure/temp -> primary somatosensory cortex
  • Spatial processing & spatial/non-spatial memory
    e.g. rats & smell order (sequence memory)
  • Fight/flight/feed/mate
  • Hormones & ANS - homeostasis (temp, weight, emotion)
    e.g. cats & rats, starvation & aggression
  • Nuclei: globus pallidus (mvt), caudate nucleus, putamen, subthalamic nucleus, substantia nigra (mvt), nucleus accumbens (reward)
  • Motor control - planned & spontaneous movement
    e.g. Parkinson's Disease
  • Reward - dopamine release
    e.g. rats self-stimulating
  • Memory, emotional expression
  • Memory encoding & consolidation
  • Spatial processing
    e.g. H.M. - anterograde amnesia
  • Relevance detector
  • Threat detection & fear
  • Fight (aggression) or flight
    e.g. S.M. showed no fear
  • Share info with contralateral side
    e.g. split for Grand Mal seizure ->
    name object in L, not see in R
  • Voluntary movement
  • Pre central gyrus
  • Homunculus
    ** Top = feet/legs/groin torso,
    bottom = hands/arms/face/tongue
    ** Larger areas for fine motor
    e.g. TMS spasm
  • Processes touch/pressure/pain/temp/proprioception
  • In post central gyrus
    e.g. stimulate cortex
  • Visual processing
    e.g. cortical blindness, achromatopsia (cannot see colour), akinetopsia (cannot perceive movement)

Primary auditory cortex

  • Gyri: bumps

  • Sulci: depressions (deep = fissures)


  • Increased surface area (less space) -> more functions (highly adaptive)

  • Executive function (abstract thinking)

Fusiform face area (R lobe)

Broca's area

  • No fluent speech
  • Inferior frontal gyrus (usually L hemisphere)
    e.g. Patient Tan

Wernike's area

e.g. prosopagnosia (cannot recognise face)

  • No language meaning/comprehension
  • L hemisphere, between temporal & parietal

Limitations of
neurobiological approaches

Description != explanation

  • Don't know how it works
  • Modern expression of phrenology

Combine with cognitive, behavioural & clinical studies
for accurate view of brain & behaviour

Brain regions heavily connected (not in isolation)

  • Spatial navigation
    e.g. hemispatial neglect