PSYC 280 Chapter 2

Nerves

Nerves

sensory fibres → connect to assoc. nuclei

Periphery

body → ex. gut, skin

Viscera

ex. glands, internal organs (ex. heart, lungs, gut)

Encephalization

worm-like animal evolves head on FRONT

White matter

set of myelinated axons

Somatosensory

touch

Olfactory

smell

Gustatory

taste

Horizontal plane

div's top/bottom → runs para to ground

Sagittal plane

div's left/right → runs from front to back

Midsagittal plane

EXACTLY in MIDDLE of left/right hemis

Coronal plane

div's front/back → runs from left to right

Dorsal

TOP (brain) / BACK (spinal cord / PNS)

Ventral

BOTTOM (brain) / FRONT (spinal cord / PNS)

Rostral (AKA anterior)

FRONT (brain) / TOP (spinal cord / PNS) → twds head

Caudal (AKA posterior)

BACK (brain) / BOTTOM (spinal cord / PNS) → twds tail

Medial

NEAR midline

Lateral

FAR from midline

Peripheral nervous system (PNS)

nerves in body → touch & mvmnt → inc. MOST inputs/outputs to brain

Somatic nervous system (SNS)

body parts w/ volitional control = ability to move by thinking → need to reach nutrients/water

Afferent nerves

• type of spinal nerve → part of SNS

• input → ENTER dorsal spinal cord

• somatosensory → feel touch / detect motion

• can move (NOT feel) muscles below cut if severed

Efferent nerves

• type of spinal nerve → part of SNS

• output → EXIT ventral spinal cord

• motor sys → synapse w/ muscles → allows to move muscles

• can feel (NOT move) muscles below cut if severed

How do signals travel along afferent/efferent nerves?

1. Sensory signals from afferent nerves move UP dorsal spinal cord to brain

2. Sensory signals = processed/felt → UPDATES motor progs

3. Motor signals from brain move DOWN ventral spinal cord to efferent nerves

4. Motor signals EXIT to muscles

Reflexes

• SMALLEST units of org of behav → exist @ spinal cord lvl

• Learning to act/move volitionally involves coord'ing/inhibiting in pattern

• Ex. afferent neuron connected to motor neuron in spinal cord

  • If afferent neuron feels stimulation, motor neuron sends signal to muscles to move

Autonomic nervous system (ANS)

• body parts w/ NO volitional control

• Things control for viscera:

  • Sensory/motor ftns → MANY involve relay ganglia

  • Rates → ex. heart rate

• Lungs have volitional control → so can consciously CHANGE breathing rate

  • ONLY way to affect body parts w/ NO volitional control → INDIR

    • Ex. can only INC heart rate by breathing HARD

    • b/c breathing = ONLY way SNS/ANS interxt

Enteric nervous system (ENS)

digestive system (AKA GI tract) → part of ANS

Sympathetic division

• division of ANS

• sympathetic chain = ganglia in chain along spinal cord → just OUTSIDE vertebrae

• Activating/arousing

  • Twds fight/flight/freeze → senses focused on dealing w/ threat

  • Active when:

    • Aroused → ex. sexually

    • Inhaling

Parasympathetic division

• division of ANS

• vagus nerve

• Calming

  • Twds broaden/build → ready to create / play / expand outwd

  • Active when exhaling

Cranial nerves

nerves in head/neck → part of SNS

cranial nerve nuclei

nuclei in hindbrain

Sensory nerves

carry info about wld that allows to sense

Motor nerves

carry signals from brainstem that allow to move

Olfactory

cranial nerve for smell

Optic

cranial nerve for vision

Oculomotor

cranial nerve for MOST eye mvmnt

Trochlear

cranial nerve for rotation & vert eye mvmnt

Trigeminal

• cranial nerve for jaw mvmnt & face sense

• ALL parts (jaw & above) = sensory → only ALSO motor in jaw

• Causes migraines

Abducens

cranial nerve for outwd horiz eye mvmnt

Facial

• cranial nerve for face mvmnt

• Motor ABOVE jaw → so wk's w/ trigeminal

• allows to express/detect emo → esp. muscles around eyes

Vestibulocochlear (AKA auditory)

cranial nerve for balance & hearing

Glossopharyngeal

• cranial nerve for taste & throat mvmnt

• Ex. swallowing → wk's w/ trigeminal (does chewing)

Vagus (AKA vagal complex)

cranial nerve comprising ANS parasympathetic division

Spinal accessory

cranial nerve for neck mvmnt

Hypoglossal

cranial nerve for tongue mvmnt

Central nervous system (CNS)

brain + spinal cord

Why is spinal cord thicker closer to brain?

includes MORE of axons from PNS

Nucleus

bundle of somas in CNS → type of bulbous struct

Ganglion

bundle of somas in PNS → type of bulbous struct

Dorsal root ganglion

1st loc. where signals from afferent neurons collected B/F moving UP spinal cord to brain

What is weight of brain (AKA encephalon)?

3lbs

Hindbrain

brainstem → contains medulla & metencephalon

Medulla (AKA myelencephalon)

• Part of hindbrain

• ANS life-support sys → above spinal cord

• WORST area to damage → ex. stroke can affect breathing/heart rate

• Contains:

  • Reticular activating system

  • Cranial nerve nuclei → cranial nerves enter/exit

  • OTHER nuclei

Reticular activating system (RAS)

• part of medulla

• sends arousing/activating signals UP to REST of brain

• midpt b/w / coordinates HIGHER brain areas & body

Metencephalon

Part of hindbrain containing pons & cerebellum

Pons

• part of metencephalon

• bulbous part → above / continuation of brainstem

• Made of white matter

  • Axons enter/exit cerebellum → send signals to coord motor progs from cerebellum to spinal cord

• Contains:

  • Cranial nerve nuclei → cranial nerves enter/exit

  • OTHER nuclei → source of neurotransmitters (ex. dopamine, serotonin, norepinephrine)

Cerebellum

• part of metencephalon

• behind brainstem

• Contains 1/2 of brain's neurons → DENSELY packed b/c SMALL area

• Stores motor progs

Motor programs

• skilled/coord'd/well-prac'd/automatic mvmnts NOT req'ing conscious thinking

• REGRESS to lvl of kid learning mvmnt if consciously think too HARD about mvmnt

• Initiated volitionally by frontal lobe

Midbrain (AKA mesencephalon)

• Contains:

  • Cranial nerve nuclei → cranial nerves enter/exit

  • OTHER nuclei → act as sensory & motor relays

Sensory & motor relays

integration pts b/w DIFF behav brain sys's

Forebrain

Contains diencephalon & telencephalon

What are the evolutionarily newest brain areas?

forebrain & cerebral cortex

Diencephalon

part of forebrain containing thalamus & hypothalamus

Thalamus

• UPPER part of diencephalon

• Sensorimotor integrator = integrates sensory perception & initiated motor progs

  • Allows to compare motor progs' EXPECTED (dev'd by brain) & ACTUAL (shown by sensory sys) outcome

    • Allows to MIN prediction error = DIFF b/w (signals about) EXPECTED/ACTUAL outcome

• Central hub for ALL brain netwks → ALL sensory pathways pass thru to comm w/ cortex

Hypothalamus

• LOWER/FRONT part of diencephalon & part of limbic sys connected to brainstem

• Neuroendocrine integrator → interface b/w nerv & endocrine (hormone) sys's

• Connects to pituitary gland

• Elec stimulating causes EITHER agg/calming behav

  • 4 Fs = fighting, fleeing, feeding, mating

• Controls/coords homeostasis / behav (ex. motivational, sexual) (drives) by integrating w/ brainstem structs

Pituitary gland

• MASTER gland → releases hormones thruout body

• creates feedbk cycle by affecting OTHER brain areas thru circulation

Telencephalon (AKA cerebral hemispheres)

part of forebrain containing basal ganglia, limbic sys, & cerebral cortex

Basal ganglia

• Subcortical part of telencephalon

• nuclei in brain → motor ftn (ex. tracking)

• Inc. part of thalamus & (debated) substantia nigra

• MINS prediction error

• Contains:

  • Dorsal/ventral striatum

  • Internal/external globus pallidus

  • Subthalamic nucleus

  • Substantia nigra

Dorsal striatum (AKA striatum / caudate putamen)

• LARGEST part of basal ganglia

• caudate + putamen

• Controls amount of force/vigour/motivation in mvmnt

Ventral striatum

• part of basal ganglia

• reward/reinforcement circuit → controls amount of motivation / effort used to get what want

Nucleus accumbens

MAIN part of ventral striatum

Internal & external globus pallidus

• part of basal ganglia

• control info flow thru basal ganglia

Subthalamic nucleus

• part of basal ganglia

• connects/coordinates basal ganglia & thalamus

Substantia nigra

• part of basal ganglia in midbrain

• Source of dopamine for striatum → somas make/send dopamine down axons to axon terminals in striatum → regulates striatum motor component

• LOSS of neurons = neural correlate of Parkinson’s disease

Parkinson’s disease

tremors → neural correlate = LOSS of substantia nigra neurons → b/c NO dopamine for striatum

Cortico-striato-thalamo-cortical loop

• neural circuit of activity where basal ganglia, thalamus, & cortex wk tog for consciousness

• Steps → 1 cycle → REPEATS:

1. Cortex sends signal thru striatum to basal ganglia

2. Basal ganglia sends signal to thalamus

3. Thalamus sends signal as feedbk to cortex

Feedback frequency

• Type of rate → see things changing FASTER as continuous INSTEAD

• Ex. flicker fusion phenomenon → see flickering light as STEADY when flickers FASTER

What is feedback frequency of cortico-striato-thalamo-cortical loop?

40Hz (cycles/s) = 25ms/cycle (+/-5) → so see things changing FASTER than 20ms as continuous INSTEAD

Limbic system

• MOSTLY subcortical part of telencephalon

• Emos

• Contains:

  • Septal nuclei

  • Amygdala

  • Hippocampus

  • Hypothalamus

  • Cingulate cortex

Septal nuclei

• Medial part of limbic sys

• pleasure & reward

Amygdala

• part of limbic sys

• emo (valence) → ex. fear conditioning

  • Inc. soc emos → ex. soc avoidance/approach/perception

• Degraded by toxoplasmosis gondii

Toxoplasmosis gondii

bacterial infection → degrades amygdala → so LOSE fear ability

Hippocampus

• part of limbic sys

• mem consolidation → mems pass thru B/F stored in LTM → ALTHO does NOT store mems

• LOSS causes anterograde amnesia

Anterograde amnesia

• CANNOT form/consolidate NEW declarative mems b/c lose BOTH hippocampi → BUT:

  • Keep OLD mems

  • Can STILL learn NEW skills → b/c stored in cerebellum

Cingulate cortex

• cortical part of limbic sys → medial & ABOVE corpus callosum

• stimulus valuation, goal tracking, self-awareness

• Parts → anterior & posterior

Stimulus valuation

amount that prefer thing

Goal tracking

check whether reached subgoals of LARGER goal → COMPLEX behav

Cerebral cortex (AKA cortex / neocortex)

• Part of telencephalon

• OUTER brain layer

• 2mm deep, 10-20bil neurons

• 5 lobes → EACH assoc. w/ MAIN sense → occipital, temporal, parietal, frontal, insular

• Transition zones b/w lobes coord / assoc. w/ BOTH senses → BETTER than 1 sense

• 6 layers → based on neuron type/struct & chara input/output

• Local categorization → based on localizing ftns → b/c MAIN senses of EACH lobe do NOT use WHOLE lobe → primary/secondary sensory/motor cortices, association cortex

  • If based on cell type → B/F - 50 areas, NOW - 150-200 areas

• Contains corpus callosum

Occipital lobe

Visual part of cortex → MOST impt sense

Temporal lobe

Auditory part of cortex → ALSO has OTHER ftns

Parietal

• Somatosensory part of cortex → ABOVE temporal & in FRONT of occipital

• Does spatial/temporal processing → ex. determine space's layout by touch

• Contains postcentral gyrus

Postcentral gyrus

• MOST anterior part of parietal lobe BESIDE frontal lobe

• Where exp touch

• Contains body plan for OUTSIDE of body

Body plan

maps which brain areas' neurons get elec stimulated when spec body part touched

Frontal lobe

Olfactory & executive ftn part of cortex → contains prefrontal cortex

Prefrontal cortex

Part of frontal cortex BEHIND motor strip

Insular lobe

• Gustatory & somatosensory (ONLY for INSIDE of body) part of cortex

  • Contains body plan for INSIDE of body (ex. viscera)

• INSIDE brain UNDER Sylvian fissure

Sylvian fissure

line div'ing temporal from frontal/parietal cortex

Gyrus

groove

Sulcus

valley

Interneurons

• inhibit/stabilize/regulate local SHORT-dist neural circuits/comm

  • binds input & output signals across layers so ALL layers send SAME signal to DIFF areas

Columns

SMALL ftn'al units / sections of cortex