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MRes Cognitive Neuroscience Exam > Single-Cell > Flashcards

Single-Cell Flashcards

1
Q

what are the two types of single - cell recording schemes?

A

intracellular and extracellular

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2
Q

extracellular electrode is what size? …

A

small electrode less than 10 microns !
LOCAL SCALE
plunged in to tissue by neurosurgeons

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3
Q

extracellular electrode has a very XXX xxxx

A

Very high impedance (M) resists the flow of current

Needs special pre-amplifier to get over this

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4
Q

what are the issues with extracellular?

A

1) Mixing of neurons (signal from other cells picked up - need spike sorting)
2) Unit isolation
3) Lack of anatomical details

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5
Q

intracellular electrode is …

A

Glass pipette electrode (<1 micron) is inserted inside the cell membrane

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6
Q

what is the pipette filled with?

A

Pipette is filled with a solution with similar ionic composition to the intracellular fluid

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7
Q

what is benefit of intracellular recording?

A

Ideal for recording graded potential leading up to spike discharge or failure of spike discharge in a neuron

Extra has no information here

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8
Q

And what can intracellular discriminate?

A

Differentiates excitatory from inhibitory synaptic activity

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9
Q

what are the issues with intracellular?

A

1) Cell damage

2) Not very feasible in behaving animal (invasive)

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10
Q

what are Complex Cells (CC) ?

A

respond to specific orientation / movement

directionally selective

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11
Q

Complex Cells are located in? and were found by?

A

first noted in V1 by Hubel DH, Wiesel T (1962)

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12
Q

other key cells discovered through single cell?

A

Hierarchical Information Processing
Mirror Neuron
Multisensory Neuron
Place Cells

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13
Q

Choose the correct statement about Action Potential (AP)

A

A. AP fire with varying degrees of input stimulation
B. The profiles of APs of one neuron can not vary depending on the state of the neuron
C. AP propagates in a decremental fashion
D. The duration of AP is approx. 2 ms

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14
Q

single cell recordings in humans are only taken from

A

medical patients with pharmacologically resistant epilepsy

MTL (mid temporal lobe) is the primary target area
– Hippoacmapus, Amygdala, Entorhinal cortex, Parahippocampal cortex

They must have failed to respond to medical management (antiepileptic drugs)

Their quality of life would be markedly enhanced by achieving a seizure-free surgical outcome. The ideal surgical candidate is a young person whose educational and vocational opportunities promise to be enhanced substantially by eliminating seizures. These patients also are ideal
• subjects for invasive brain research.
• Third, their seizure focus must be localized to a circumscribed portion of the brain that can be safely removed surgically

Average hospital stay = 7-14 days

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15
Q

what is their treatment ?

A

Electrodes are surgically implanted to localize the focus of the seizures

Treatment Removal of brain tissues generating seizures

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16
Q

What are the 5 main Advantages of Single Unit Recording in Humans?

A

1) Signal source: Direct recording
2) Spatial resolution: 1-2 mm (EEG ~ cm)
3) Temporal resolution: ~ ms
4) Signal-to-noise ratio: (less artefacts, i.e. no blink artefacts)
5) High frequency brain activity

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17
Q

Acute Recording is ? and USES WHICH ELECTRODE ?

A

critical to do immediately - > No requirement of preoperative diagnostic testing.

no time - done quickly

microelectrode

always conscious - to communicate if the tissue being removed has no sig imput - minimal impact of removed tissue

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18
Q

details of an acute recording?

A

> No requirement of preoperative diagnostic testing
Experiments inside the operating room
Max duration of experiment = 30 min
Noisy/challenging environment; no room for debugging faults Patient’s responses are limited (simple verbalization or button press)
Patient is in supine position (minimal movement is allowed)

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19
Q

What is chronic recording?

A

more common

when unsure of location

  • There is some residual uncertainty about the location of seizure foci
  • Requirement of additional diagnostic testing (recording from electrode arrays chronically implanted)
  • Experiments are carried out in a specially equipped hospital suite (less noisier than Acute recording)
  • A lot of variability (devices, techniques, protocols) across epilepsy centers
  • Patients are less restricted and more demanding tasks can be performed
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20
Q

what is MRI used for in single-cell?

A

locating exactly where electrodes are placed

• Pre- and post- MRI scans are necessary to localize electrodes

21
Q

In chronic recording, the patient is often tired, why?

A

– Doctors need patients to have fits to discover where they come from.
– Usually antileptic medication is lowered to increase the chance of epilepsy
– If no seizure is recorded, patient is often sleep deprived

fits keep peeps up at night

22
Q

In chronic recording, tests at two points are required… why?

A

Cognitive and sensory functions are tested through testing
– Both pre- and post-operative testing are necessary in order to ensure that IQ, visual function and other factors won’t confound the data

23
Q

when is chronic testing done?

A

• Testing is done several days after electrode implantation

Testing window spans only for a few days when the patient is awake and alert, has minimal seizure, and not sleep- deprived

24
Q

What are the 3 main practical/technique steps of single -cell recording?

A

1) Amplification (1000-5000)
2) Notch Filtering (50 Hz ± 1 Hz) [60 Hz in USA]
3) High-pass Filter (250-300 Hz)

25
Q

What si the common sampling frequency of single-cell?

A

~ 20 kHz (high frequency data, so high sampling rate)

0.05 every millisecond

26
Q

what two kinds of recording style are there?

A 
Continuous Signal
Discrete signal (signal > threshold)
27
Q

What are the two types of neuronal coding?

A

rate

temporal

28
Q

what is rate coding ?

A

Number of action potential
– Information is in the mean firing rate of the neuron
– Most widely used and understood
– Robust for recognition and processing of static objects, – Less suitable for fast and dynamic action

29
Q

what is temporal coding ?

A

– Information is in the timing of the spike

– No precise definition, anything not based on rate can be based on timing (most important is neuronal synchronization)

30
Q

what is spike detection and sorting?

A

detecting signal from noise

separating signal from an intended neuron, against a neighboring neuron or group of neurons

Spike Sorting – Neural Cocktail Party Problem

31
Q

core features of spike?

A

Spike amplitude
Spike waveform
Firing rate

Additional features:
Context
Correlational function
Modulation of loudness by prosody

32
Q

spike sorting techniques ?

A 
Raw data
filtered data
spike detection 
feature extraction 
clustering 
Misc. spike sorting method: 
PCA based (principal components)
ICA based (independent components)
Other classifiers
33
Q

how do we usually display single - cell?

A

Peri-Stimulus Time Histogram (PSTH)

  • Align spike sequences with stimulus onset (or any event) which repeated n times
  • Divide the stimulus period S into N bins of size D
  • Count the number of spikes (ki) within individual bin for all trials
  • Compute the histogram

Basically counting how many times it fires in response to an event

34
Q 
The typical sampling frequency used for recording single neuron activity is
A. 2KHz
B. 20 KHz
C. 200 KHz
D. 200 Hz
A

B. 20 KHz

35
Q

Which of the following features is not used in spike sorting?.
Spike shape
Spike amplitude
Firing rate

A

well all of them. unclear actually (i emailed joy)

possibly they were looking for all

36
Q

Which of the following features is not used in spike sorting?.
Spike shape
Spike amplitude
Firing rate

A

well all of them. unclear actually (i emailed joy)

possibly they were looking for all

37
Q

Neurons should have discernible statistical differences….

A

in their firing patterns in response to the different external stimuli

38
Q

what is a Responsive Neuron?

A
  • Activity at task is different than activity at baseline
39
Q

what is a (Category) Selective Neuron

A

Activity for the category is different from baseline activity

  • Activity for the category is different from baseline activity
    (t-test, Wilcoxon test)
  • Differences in activity among categories
    (ANOVA)
  • Differences in activity among pair-wise (selected category vs any category) (Wilcoxon test)
  • No differences in activity to distinct
    individual stimuli within the category
    (ANOVA)
40
Q

example of a category neuron / Single Neuron & Object Recognition

A

1) Famous face neuron in hippocampus
2) Spatial encoding hippocampi = place cells in rats and taxi drivers from hugo spiers
3) Entorhinal Cortex coding ‘Animal’ Category

41
Q

what about difference between perception and imaginary ?

A

Kreiman et al (2000)

= Correlation between Perception & Imagery

• Three types of neurons – Visual selective
– Imagery selective
– Both selective
• Tight coupling between perception and imagery
• Role of MTL in imagery

42
Q

what is Visual Invariance?

A

Quiroga et al (2005)

Out of 132 neurons, 51 showed invariance to a particular individual, landmark building, animal or object

  • Are these neurons ‘grandmother cells’?
  • These cells make link between perception and long-term memory
  • Representation is fairly abstract and invariant
  • Possibly they are crucial for storing new associations
43
Q

what is one-shot learning ?

A

Rustihauser et al (2006)
MTL neurons
• contain information
sufficient for reliable novelty- familiarity discrimination
• show rapid plasticity as a result of single trial learning

sequences of faces - new face or old face?

44
Q

Emotion & Single-Unit Response

A

Kawasaki et al (2001)

Emotion Processing by PFC Neurons

45
Q

‘Mirror Neuron’ in Humans

A

Mukamel et al (2010) Current Biology

  • A significant proportion of neurons in Supplementary Motor Area (SMA), hippocampus responded to both observation and execution of actions
  • A subset of neurons demonstrated excitation matching, another subset inhibition matching, and a final subset excitation-inhibition matching
  • Existence of multiple systems with neural mirroring mechanisms for flexible integration and differentiation of perceptual and motor aspects of actions performed by self and others
46
Q

Clinical applications of single-cell?

A
  • Epileptic subjects: Localizing seizure foci
  • Depressive/ OCD: Cingulotomy
  • Parkinsonian
  • Brain-computer-interface
  • Neural Prosthetics
47
Q

Limitations & Open Challenges

A
  • Only patients can be participants (poor generalizability)
  • Total experiment time is limited (usually 1 week)
  • Effect of medication
  • Heterogeneity of participants (age, cognitive skills, task performance etc)
  • Brain areas of study are limited by clinical constraints
  • Electrodes cannot be moved
  • Number of brain areas to study simultaneously are limited
  • Poorly understood spontaneous activity (“resting state”)
  • Possibility of microstimulation to the neurons to explore the causal role in perception
48
Q

in comparison to other techiniques, single-cell offers…

A

Single-neuron recording offers the best temporal and spatial resolutions

A diverse range of brain functions are represented by the activities at micro (neuronal) level

but

  • But only patients can be the participants
  • Recording is very invasive and complex

MRes Cognitive Neuroscience Exam (9 decks)

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