Lecture 1:
Cognitive Psychology: Study of the mind. Functional explanations; process models. How do
these processes interact?
Biological Psychology: Study of the biological basis of the mind. Focus on brain processes;
structural models. How do brain areas interact?
Nowadays integration: cognitive neuroscience. Dus nu processes (e.g. LTM, perception..) +
how does it work in the brain (biological basis)? Want cognitive en biological zijn niet anders,
different perspectives of more or less the same thing: human mind and human behavior.
Cognitive neuroscience: very young science. Why? 1. Long-time dominance of body-mind
dualism. Now: “the mind is what the brain does” 2. Het was ook lastig om al die dingen te
onderzoeken: nowadays technological developments: fMRI (and PET).
Cognitive psychology: 19th century.
1860: Weber / Fechner’s law. Psychophysics. Relation physical energy to sensation
1867: Hermann von Helmholtz. Examine how individuals subjectively interpret outside
world. Proposes perception as process of unconscious inferences about the world. Dus niet 1
op 1 representatie van wereld.
1879: Wundt opened first psychology lab
1886: Ebbinghaus’ memory research.
Physiological chronometry (timing of biological/mental processes): Johannes Müller (first
half 1850). Nerve conduction velocity is infinitely fast (niet waar overigens). He came up with
term ‘’spiritual Lebenskraft”: spiritual/mental force that guides biological processes, that
leads to nerve conduction through brain. Interaction mental and biological aspects!
Von Helmholtz (1850): Nerve conduction velocity = 30 m/s (frog) and 60 m/s (human).
Physiological chronometry paves the way for mental chronometry. Mental chronometry:
Fransiscus Cornelis Donders: he did something similar, maar dan niet met nerves maar met
mental processes. Donders’s idea after Helmholtz’ discovery that nerve conduction velocity
is not infinite: als nerve conduction tijd inneemt, is het dan niet ook zo dat mentale
processen tijd kosten? Rests on two assumptions: 1. Nerve conduction takes time dus ook
mentale processen take time. 2. We can measure that time. How?
Donders’s subtraction method: Goal: Estimate duration of a postulated mental process, X.
Method: Create two identical tasks (virtually identical), except for involvement of X: dus one
task includes X, the other does not. Measure RT in both tasks. Subtract
RTs: dus RT met X – RT zonder X -> Duration of X. VB:
1. First task: GO/ No-go task. Stimulus: green dot (ja zeggen+ next
klikken) or blue dot (next klikken). Opdracht: Respond only to
one color; not to the other. Can we find out how long it takes to
distinguish blue from green? (This question is our X).
2. Second task: simple RT task. No X. stimulus green and blue dot. Always respond: yes
en next.
3. RT (go-nogo) – RT (simple) = stimulus discrimination time.
Problems: 1. Depends on assumptions about stages. Not entirely correct. Het is niet zo dat je
eerst detecteert, dan discriminate en dan motor. As soon as you start to detect it, begint ook
discrimination. Het is niet dat je wacht tot het einde van de fase. 2. Strong assumption
about stages being independent. Processing of later stages changes the processing of earlier
stages. Kortom: there is a lot of interaction going between the stages.
,Ebbinghaus: hij gebruikte zichzelf als subject. Procedure: Study phase: learn a list of
nonsense syllables (e.g. DAX, ZUG, YOP, …) to perfection. Register time this takes. Wait a
certain time (minutes, day, several days): memory decay. Test phase: Register how long it
takes to relearn the list. Calculate percentage of savings.
Era of behaviorism: 20th century.
John B. Watson (1913). “Behaviorist manifesto”. Ignore the mind, mental processes;
Exclusive focus on behavior: input and output bestuderen. S – R psychology (stimulus and
response). Focus on learning: dominant paradigms:
- classical conditioning (Pavlov) “conditioned reflex”
- Operant conditioning (Skinner) reinforcement learning
Research tradition still alive and kicking. BUT interpretation has changed -> S – O (organism)
–R
Towards a cognitive interpretation: Tolman: what the rat learns is: NOT a behavioral
response (“turn right for food”) BUT a “cognitive map”. That is what the rat uses to find the
food -> S – O – R.
Cognitive psychology: Core: human as information
processor. Input (stimulus) -> processing -> output
(response) (zie plaatje: processing = LTM+STM).
Measuring “central processor” speed: Scanning short-term memory. Memorize:
H and L. en dan krijg je steeds lijst met letters, en moet je aangeven of H of L
erin zit. Hoe meer letters je moet onthouden, hoe groter je reactietijd.
What happens? Now:
From the retina visual info travels via the lateral geniculate nucleus in thalamus to the
occipital lobe (the visual receiving area).
From there it is distributed to the brain. 2 primary pathways: Dorsal (space and actions;
“where/how”): from occipital lobe to parietal cortex. Ventral (concepts; “what”, identity):
from occipital lobe to temporal cortex.
Daarna to frontal cortex: goals, motivations enz. Interactions with behavoural goals &
motivations (frontal). Here: task rule.
Daarna passed back to Premotor cortex / supplementary motor area -> Primary motor
cortex.
From primary motor cortex -> spinal cord.
This leads to: Spinal column -> effector (a response)
The brain: how do we know?
- Neuropsychological studies with patients (strokes; accidents). Dus patients met brain
damage: they show impairments -> compare that with control subjects. Dan weet je
dat brain region has something to do with a specific function. Double dissociation:
the double dissociation: evidence for localization of function: Functions A and B are
served by different brain areas.
- Brain imaging techniques.
, o EEG / MEG . EEG: Electrodes register electrical activity on the scalp, as
produced by the brain. MEG is similar to EEG, except that coils register
magnetic activity produced by the brain. Both techniques allow us to derive
event related potentials (ERPs). We “time-lock” the EEG or MEG signal to an
event in the outside world (a stimulus or a response). Individual trials are very
noisy. Dus heel veel trials en daarna averaging. Then time lock to certain
event. Dan krijg je ERPs: pieken en dalen. De negatieve toppen krijgen een P
gevolgd door nummer, en de negatieve een N. EEG and MEG are direct
measurements of neural activity. Maar dus niet measured from the source,
maar van scalp.
o PET and fMRI. Indirect measurements of neural activity. fMRI: Principle:
Active brain areas attract blood (need oxygen). Oxygen reduction in
hemoglobin -> change in magnetic properties. fMRI detectors pick up the
changing magnetic properties. fMRI (like PET) measures neural activity
indirectly, via differences in local blood supply. Zowel fMRI als PET gebruiken
het feit dat actieve delen zuurstof gebruiken. Voor fMRI: zuurstofreductie,
zorgt voor een verandering in magnetische eigenschap. Dus bij fMRI kijk je
naar bloodflow. Maar dat is dus relatief langzaam, dus je kunt niet snel laten
zien, maar wel precies laten zien waar.
- Single cell recordings. Measures activation of a few neurons in behaving animals or
patients under surgery.
Temporal resolution (how precise in terms of time) vs. spatial resolution (how precise in
terms of location):
- EEG: high temporal resolution (accurate in showing when something happens); low
spatial resolution (inaccurate in showing where the activation is coming from).
- fMRI: low temporal resolution; high spatial resolution.
- Single cell recordings: Highest spatial & temporal resolution
Bij single cell recordings bleek dat specifieke neuronen reageren op zeer specifieke stimuli.
So, do we have “grandmother cells” (dus een neuron grootmoeder, een neuron vriendin, ....)
? How specifically do neurons represent information? One person one neuron? Very
uncertain, because there may be more neurons sensitive to Jennifer Aniston. Als die ene
neuron afsterft, kun je mensen dan opeens niet meer herkennen? Nee. A neuron sensitive to
Jennifer Aniston may also be sensitive to other pictures.
Distribution across brain areas: Properties, like shape, color, sound, movement may belong
to a single object or event. Yet, they activate different brain areas. The brain is a distributed
neural network, like an orchestra with different instruments playing in perfect harmony.
Lecture 2
Bonding elements: 1. Ionic bond (electrostatic force). Dus plus trekt min aan, bijv NaCl =
keukenzout. 2. Covalent bond (sharing of electrons forms molecules). Denk aan water. H
heeft maar 1 elektron buitenste schil, en zuurstof maar 6, dus die twee gaan binding aan. De
8+ protonenkern trekt harder aan elektronen dan waterstofkern, dus de zuurstof is meer
negatief dan waterstofatomen.
, Covalent bonds: vb 1: glucose (C6H12O6). Vb 2: aminozuur: altijd een aminogroep, een
zuurgroep (=carboxylgroep) en een sidechain (die verschilt, koolstofatomen). Vb 3: een
keten van aminozuren = eiwit. Korte eiwitketens = peptides. Vb 4: lipids (fat). Lange
koolstofketens, gemaakt door covalente binding. Vb 5: fosfolipiden. Bestaan uit hoofd en
twee hydrofobe vette staarten. Hoofd is ook een covalente binding, maar wel met fosfor (P),
dus hoofd is netto negatief geladen (Want fosfor heeft negatieve lading). Daarom is het
hoofd hydrofiel (want watermoleculen zijn positief geladen bij waterstofatomen). Staarten
zijn niet geladen, hydrofoob. Double layer of phospholipids forms cell membrane.
Neurons:
Inhibitory + excitatory signals -> het totaal beslist of er action
potential komt.
Axon is covered with fatty layers: myelin sheath, speeds up
electrical conduction of action potential.
Transcription: genes are read from the DNA and converted to
messenger RNA (mRNA). mRNA then leaves the nucleus through
the pores, and is read out by ribosomes (complex of proteins), to form a new protein.
Produced proteins then have to travel through axon to terminal buttons: for this there is a
special kind of protein: Kinesin: Lopende ‘mannetjes’ over de microtubuli. Dynein: Weer
zelfde ‘’mannetjes’’.
Oligodendrocyten en Cellen van Schwann.
Astrocytes Take nutrients out of blood and give to neurons. Belangrijk want: bloed-
hersenbarrière (BBB). Neuronen hebben nutriënten en glucose nodig. Dus astrocyten zetten
zich tegen bloedvaten in brein: extract nutrients from bloodstream. Geven die nutriënten
aan neuronen. Bijv bij glucose: convert glucose in blood to lactate en geef dat direct aan
neuronen of convert glucose to glycogen and store that.
A neuron is a small battery! Can hold a charge.
Electrostatics en diffusion.
The membrane contains ionkanalen (Na+, K+, Cl-, etc). makes membranes permeable. At
rest: inside cell worden eiwitten gemaakt. A- kan uberhaupt niet naar buiten. K+ ionen
lekken wel naar buiten at rest via kaliumpoorten. Maar binnenkant wordt steeds negatiever.
Daardoor wordt het voor K+ steeds lastiger om naar buiten te gaan. Op een gegeven
moment is electrostatic pressure zo hoog dat K+ niet meer naar buiten kan. Dat is dus
ongeveer bij -70/65 mV.
Na-K pomp . 24/7 is deze pomp actief, en dus highly energy consuming (ATP). Dus hierdoor
wordt inside of cell negatively charged gehouden.
Dus: 1. Na+ wil naar binnen door zowel de electrostatische druk (binnenkant is negatief
geladen) als diffusie (hogere concentratie Na buiten dan binnen). 2. K+ wil naar binnen door
electrostatische druk, maar naar buiten door diffusie. 3. chloride ionen naar buiten door
electrostatische druk, maar naar binnen door diffusie.
