3 - conceptual issues + methodologies

  • watch video (HM and memory task)

  • watch video (VR testing)

  • watch video (EEG)

  • make flashcards for the tech parts

What’s the difference between attention and memory?

  • focused attention makes it more likely for memories to be encoded, stored or retrieved.

  • lapses in attention make it less likely for memories to be encoded, stored or retrieved.

  • Attention as a spotlight:

    • amplifies components of your conscious experience/environment

Mindfulness to reduce distractibility

  • aims of mindfulness: attentional control, emotion regulation, self-awareness (self regulation)

  • anchor: object to return attention to when mind has drifted (usually breath)

    • gently returning to anchor is only action taken (aside from observation)

  • stages of mindfulness:

    • early: effortful doing

    • middle: effort to reduce mind wandering

    • advanced: effortless being


MISC FACTS

cerebellum’s Purkinje neurons have 1 million synapses

average is 1000 synapses per neuron!

number of neurons in brain: 86 billion

number of neurons in cerebral cortex: 20 billion

synapse: fundamental storage unit in the brain


Is LTP memory?

  • experience inducing LTP caused by high frequency electrical events

    • done artificially (with electrical signals) instead of sensory inputs in ecological contexts

      • doesn’t represent behavioural experience

  • it is the fundamental source of hypotheses about how brain makes memories. NOT whole story about how brain makes memories.

ode to lab rats ❤


Paradigm:

  • inferred memory trace when training experience influences behaviour.

How can we study memory?

  • damage brain region

  • inject drugs into brain to influence aspect of neural function

  • modify DNA to increase or decrease expression of molecule

** however, hard to isolate Memory as the only affected component. must do other experiments to rule out other component processes.

LTP: first domino is NMDA receptor!


How can we categorize memory traces?

  • 3 dimensions: duration, state, vulnerability to disruption

  • active: “in mind”

  • after a memory’s initial formation, additional post-acquisition processes stabilize the trace (memory consolidation)

  • older memories are more resistant to disruption than new memories


How can we study the phenomenon of time-limited retrograde amnesia?

Electroconvulsive shock therapy (attempted)

  • Cerletti and Bini

    • electrical current across brain to treat psychiatric disorders

  • not super successful at providing more insight experimentally.


How do we test memory in humans?

Wisconsin card sorting task

  • sorts cards (by color, shape, number) and invigilator tells them correct/incorrect

  • measures memory and executive function (perseveration- DLPFC)

Neuropsychological testing

  • various tests for different domains.


What are some ways to measure memory in the brain?

Neuroimaging

  • structural: static (MRI, CT)

    • focus on spatial resolution

  • functional: how is the brain changing over time? (fMRI, PET, EEG)

    • focus on temporal resolution

CT (Computerized Axial Tomography) scans: useful for diagnosis, stroke/brain tumour…

MRI (Magnetic Resonance Imaging): apply strong uniform magnetic field (aligning protons in atoms) and “let it go” to see contrasting

fMRI (functional magnetic resonance imaging): changes based on blood flow. blood oxygen-level dependent (BOLD) contrast

  • neuronal activation and cerebral blood flow are coupled (related)

  • NOT informed about inhibitory or excitatory (or individual neuron activity in general, just about broad locations of activation that blood flows towards)

PET (Positron Emission Tomography) scan: radioactive tracer in bloodstream indirectly measures blood flow

  • assumption with both fMRI and PET is that higher blood flow indicates higher brain activity

EEG (electroencephalography): can change spatial resolution by changing # of electrodes on scalp. but overall not precise.

MEG (Magnetoencephalography): sensitive device, small local changes in magnetic field orientation or strength

  • indicate fast temporal current flow changes.

  • very good functional neuroimaging due to high temporal resolution.

TMS (transcranial magnetic stimulation): current flow around coils generate magnetic field to stimulate certain cortical regions. induce a current.

  • can be used to treat treatment-resistant depression, can assess normal function


SIDENOTE about exercise 1

  • developing personal mnemonic procedures (like mind palaces!!!)

  • think: what modalities to use?

    • *should have motor component

    • visual

    • auditory

    • somatosensory (tactile)

hippocampal index theory for declarative memories