This is a summary of 3.6 Neuropsychology. Some of the literature might differ as this is based on literature used during covid and online tutorials. I added tables to summarise the main points which really helped me for the exam, I hope it helps you too!
Part 0: Intro:
Reading 1: Kolb (2015) – Organization of the motor system (p.232-250 – chap.9):
(Skip Spinal Cord paragraph)
• INTRODUCTION:
o Picking a coffee mug:
Visual system (determines which part to grab) -> visual cortex
gives this info to motor cortex (this plans to initiate the
movement) -> sends info to part of the spinal cord (this controls
your arm & hand muscles)
Sensory receptors (send message mug is grabbed to sensory cortex)
• Sensory cortex tells motor cortex the mug is being held
Basal ganglia = helps produce appropriate amount of force to grab mug
Cerebellum = corrects movement errors (timing & accuracy)
o Many parts of brain are activated for smallest actions
o Motor system = mainly used for movement
Spinal cord -> commands muscles (through peripheral nerves)
o How do the brain & spinal cord work together to make movements?
Neocortex + brainstem + basal ganglia + cerebellum how they contribute?
• THE NEOCORTEX: INITIATING MOVEMENT:
o Posterior cortex = movement goals – sends sensory info to PFC
Prefrontal cortex (PFC) = generates plans for movements
Premotor cortex = has a movement repertoire – organize movement sequence
Primary motor cortex (M1; Brodmann’s area 4; precentral gyrus) = more
basic movements (e.g., hand & mouth movement)
Simple movement => posterior -> premotor & M1
Complex movement => posterior -> planning in temporal & PFC -> premotor & M1
(e.g., when using finger to go through maze)
• Mapping the motor cortex using electrical stimulation:
o Penfield did this -> found most action in M1
Dorsal part of premotor cortex (= area 6/supplementary motor cortex)
He stimulated these brain parts with electrical pulses & people moved
o Homunculus (“little human”) is spread out across M1 (upside down)
Body is symmetrical -> each side has same homunculus rep
Found secondary one in sup motor cortex
Body sizes are disproportionate (e.g., big hands) -> bigger parts = more
precise/fine motor control there
• Multiple representations of the motor cortex:
o Tech advancement -> did same as Penfield but with microelectrodes = found many
more homunculi (≈10) – probs not as simple as he sketched
E.g., different locations for each finger
• Natural movement categories:
o Graziano -> used 0.5s electrical stimulation in conscious monkeys
Found “ethological categories of movement” – that monkeys use everyday
(e.g., hand movement to mouth to eat; climbing; chewing; defense…)
Stimulating specific area will do same movement but in dif ways depending
on starting position
1
, Hand stays there if keep stimulating + :/ hits object if it’s in the way
o 3 types of organization in each region (body part to move; special location of where
movement is directed; movement function)
Flexible map (depends on past/recent experience, objects available)
o Penfield + Graziano = whole body movement in dorsal premotor cortex
Hand/reaching is ventrally
Hand movement to mouth in most ventral part of premotor cortex
-> Whole body movements more in premotor cortex + more discrete in M1
• Visual-parietal-motor connections:
o Can also get movements by stimulating parietal cortex
Parietal topography = mirrors homunculus
Stepping -> dorsal – reaching -> medial – hand & mouth -> ventral
o E.g., reaching = visual cortex (shape & location) -> parietal (id body part that will
contact the object-reach out) -> motor (moves arm to grab it)
Movement itself = from brainstem or spinal cord
Movement = premotor (whole body) + M1 (discrete) – but also the parietal cortex!!
- Homunculus (Penfield)
• The movement lexicon:
o Graziano -> support for movement lexicon
E.g., many mammals use pincer grip (thumb & index) to grab stuff -> lesions
in thumb area of homunculus = weak thumb + poor coordination linked to it
(i.e., can’t pincer grip)
-> This stuff ≠ just learned – but part of vocab in pre-wired lexicon
o Different in every mammal (more complex in humans)
o Premotor cortex repertoire = more complex > M1 (specific stuff)
E.g., monkey can make hand movements (M1) but not coordinate them (PM)
o Fukuda -> learning to move = learning how to use pre-organized movement
o Motor cortex -> plans action – firing more pre-lifting (+ more when heavy)
Movement direction
Monkey with lever -> move towards him = max neuron discharge
• The discharge reduces as you go more far away from this position
• Motor cortex = calculates direction + distance
• Mirroring movement:
o Activity in premotor cortex when making movement + when seeing someone else
do this movement (≈sympathy)
= Mirror system neurons (= encode goal of an action)
Doesn’t always happen (e.g., only f object within reach)
Some still respond when change in target/size
• Some can fill in the blanks (e.g., when only see part of movement)
o Monkeys -> core mirror neurons = more broadly tuned – wide range of actions for
obtaining a goal (= transitive movements) – includes parietal/motor circuit
o Humans -> core mirror neurons = transitive movements (= goal) – includes Broca’s area
Distributed system = respond to intransitive movements (≠ goal)
Flexible properties of mirror neurons = ability to imagine movements
• Control BCIs
o Mirror neuron theory = we understand own & other’s actions by internally
replicating the movement for it
-> Self/social-awareness + awareness of intention/action of others
Probably important for verbal & gestural language
Lack of empathy (seen in autism) -> maybe cause of mirror neuron dysfunction
2
, Mirror neurons = internally replicate other’s actions -> helps us understand their actions
- Helps us imagine movements / Part of premotor cells
Core mirror neurons = transitive movements (= goal) – in ventral parietal + ventral premotor
& motor
• THE BRAINSTEM: MOTOR CONTROL: (automatic movements)
o 26 pathways from brain stem to spinal cord
Info on balance & posture – control automatic nervous system
Often whole body movements (≠ neocortex)
o Hess -> implemented electrodes into brain of animals – then to
stimulating lead
Stimulate part = sudden movement (e.g., erect hair in cat)
Could also modulate animal’s emotional behavior (e.g., excitement vs fear)
o Brainstem functions = posture; standing up; coordinate movements; swimming;
walking; drinking; sex; grooming…
• The basal ganglia & movement force: (non-automatic movements)
o Basal ganglia = collection of subcortical nuclei in forebrain – connect motor
cortex to midbrain + sensory regions of neocortex to motor cortex
Caudate putamen (= large cluster of nuclei under frontal cortex)
• Part of it extends into a tail in temporal lobe – ending in amygdala
o BG = receives input from 2 main sources
All areas of neocortex & limbic cortex (includes motor) project to it
Nigrostriatal dopamine pathway (from substantia nigra)
• (Vice versa -> BG sends back to motor & substantia nigra)
Caudate + Putamen = main part of basal ganglia (part of striata)
- Basal ganglia = send & receive to motor (neocortex) + substantia nigra (force control)
o Movement disorders caused by damage in basal ganglia:
1. Damage in caudate putamen -> leads to unwanted movements
(dyskinesias – hyperkinetic)
• Seen in Huntington’s disease + Tourette’s syndrome
2. Cells of basal ganglia left intact + damaged input -> difficulty making
movements (hypokinetic symptoms) – loss of dopamine from sub nigra
• Parkinson’s disease (loss dopamine cells in substantia nigra + their
input into the basal ganglia)
=> So one of its major functions must be to modulate movement
Problems with basal ganglia = hypo/hyperkinetic / so must link to movement
o Keele & Ivry -> BG’s underlying function = generate force required per movement
Tested by asking people to press button (force determined line length)
• (People with BG dysfunction pressed to
hard/lightly
o Redgrave -> 2 pathways to motor cortex
Excitatory & inhibitory pathways
If indirect pathway dominates -> excitation of
GPi = inhibits thalamus = lower movement
If direct pathway -> inhibition in GPi = more
activity in thalamus = amplifies movement
Globus pallidus (GPi) = where both paths
converge – determines strength of movement
• Lower/destroying/stimulate it this can help Parkinson’s patients
Inhibitory/indirect = high GPi -> low thalamus -> low movement
3
, Excitatory/direct = low GPi -> high thalamus -> high movement
• The cerebellum & motor learning:
o Cerebellum = acquiring + maintaining motor skills
Under cerebral cortex – above brain stem
Smaller but contain 4x more neurons than neocortex
o Flocculus (small lobe on ventral surface of C – eye movement & balance)
Homunculus (middle linked to face…)
o Pathway between 2 hemispheres/midline -> cerebellar nuclei -> brain regions
Tumors/damage here = disrupt balance + eye movement + posture +
walking – but not other movements
Damage in lateral parts = disrupts arm + hand + finger movement
o 2 main ideas about cerebellum’s link to movement = (1) timing; (2) accuracy
Keele & Ivry support (1)
• Study -> damaged cerebellum difficulty in taping in rhythm
• Another found they were bad at estimating time duration
• => Loss in timing – in movement & perception
Thach (2)
• Study -> dart throwing with weird glasses – lean to left
o Healthy people correct error until good with glasses on –
then overcompensate when no glasses to right at start
o ≠ Unhealthy (never correct when glasses on)
• => Movements depend on accuracy adjustment made by C
o Feedback chains:
What you want to do vs what you actually do
• Correct first depending on feedback of second
=> Cerebellum likely involved in improving our stuff (e.g., painting)
Cerebellum = acquire & maintain skills / Timing & accuracy of movements
- Help us improve on stuff (through feedback)
Helps us combine simple movements into more complex ones
M1 = program movements
M2 = program movements Supplementary motor cortex (SMA) + premotor (mirror neurons)
Basal ganglia = modulate motor output + cog processes Complex of connected nuclei
Cerebellum = receives info from M1 & M2 -> integrates it with external input – motor learning?
4
Les avantages d'acheter des résumés chez Stuvia:
Qualité garantie par les avis des clients
Les clients de Stuvia ont évalués plus de 700 000 résumés. C'est comme ça que vous savez que vous achetez les meilleurs documents.
L’achat facile et rapide
Vous pouvez payer rapidement avec iDeal, carte de crédit ou Stuvia-crédit pour les résumés. Il n'y a pas d'adhésion nécessaire.
Focus sur l’essentiel
Vos camarades écrivent eux-mêmes les notes d’étude, c’est pourquoi les documents sont toujours fiables et à jour. Cela garantit que vous arrivez rapidement au coeur du matériel.
Foire aux questions
Qu'est-ce que j'obtiens en achetant ce document ?
Vous obtenez un PDF, disponible immédiatement après votre achat. Le document acheté est accessible à tout moment, n'importe où et indéfiniment via votre profil.
Garantie de remboursement : comment ça marche ?
Notre garantie de satisfaction garantit que vous trouverez toujours un document d'étude qui vous convient. Vous remplissez un formulaire et notre équipe du service client s'occupe du reste.
Auprès de qui est-ce que j'achète ce résumé ?
Stuvia est une place de marché. Alors, vous n'achetez donc pas ce document chez nous, mais auprès du vendeur eurpsychology. Stuvia facilite les paiements au vendeur.
Est-ce que j'aurai un abonnement?
Non, vous n'achetez ce résumé que pour 10,49 €. Vous n'êtes lié à rien après votre achat.
