Welcome to the future: computational neuroscience Flashcards
Why is computational neuroscience important?
It helps us understand complex networks like those in the brain.
Why do we use it?
To model neural circuits and network functions
What is it?
The mathematical modelling of core features of cells, circuits and neural networks
What are sequences of actions?
Units that are either hierarchical or serially organised into adaptive behaviour
What are the two brain regions that are known to be involved in action selection?
1 human and 1 from the fruit fly
human: basal ganglia
Insect : central complex
What are the 4 main components of the basal ganglia?
1) caudate nucleus
2) the putamen, which together forms the striatum
3) the globus pallidus, which is the outer and inner segment
4) subthalamic nucleus and the substantia nigra, and they together innervate the thalamus.
the mushroom bodies, MB, which are kind of the hippocampus in an insect
true or false
tRUE
What are the three fundamental features of the insect central complex?
1) Connections from the protocerebral bridge (PB) to the ellipsoid body (EB) (columnar neurons)
2) FB-EB neurons and EB ring neurons: intersect the neuropil (meshwork) (tangential neurons)
3) Columnar and tangential neurons innervate these neuropil.
All of the cells responded in the same way, and together they produce a coherent output
true or false
FALSE
None of the cells responded in the same way, but together they produce a coherent output
What are the parts needed to generate an action potential in an insect?
Soma, axon, synaptic currents, voltage-gated currents
Who developed a model and insight into action potential propagation?
Huxley and Hodgkin
What are the physiological features of a neuron and its axon. There are 3 currents and one potential?
potassium current
sodium current
leakage current
membrane potential
Core features of neural activity
Action potential resembles core aspects of a sine wave.
true or false?
TRUE
What does a sine wave resemble?
a circular motion
What is a Period T?
a full circle
Circular frequency is also called what?
angular velocity omega
Circular frequency can be defined by?
period T
the frequency of the angular movement can only be short.
true or false?
False
The frequency of the angular movement can be short or long
Frequency in the time domain is called?
Hertz
To describe idealised action potential, we need what 2 things?
period T and amplitude
We can describe a sinusoidal wave by what 3 things?
angular velocity [ω], period t and frequency in the time domain.
Action potential resembles core aspects of 2 things?
rotating phasor and sine wave
A firing action potential can be described as a?
quasi-periodic sine wave
Multiple firing action potentials can be described as?
multiple quasi-periodic rotating phasors
Circuit and network activity can be described as?
the sum of multiple sinusoidal waves in the time and frequency domains.
Circuit and network activity is the result of multiple sinusoidal waves that influence each other; the resulting sum can be calculated and described with?
the Fourier Transform (FT)
Neural activity is not always periodic.
true or false?
true
Neural activity is often aperiodic.
Each 360 degree turn in phase space corresponds to a burst of the neuron
true or false?
true
What is an Attractor state?
a point in phase space to which the system converges
Neural activity is not only aperiodic, its also?
Chaotic
Neural activity of an open nonequilibrium system can be described as a?
dynamical nonlinear phase transition of attractor state.
Neural activity of circuits in networks are nonlinear dynamical systems, and cannot be described with linear dynamics.
true or false?
true
Neural circuits and networks can be described as nonlinear dynamical systems
What are the 3 nonlinear systems?
(1) Instability
Dynamical systems operate near instability:
• respond rapidly with a large, flexible repertoire of sensory and motor patterns
• rapid response is important for animal behaviour (eg avoiding predators)
(2) Phase space
Dynamical systems can be described in a phase space:
• a mathematical space with independent coordinates representing the dynamic variables needed to specify the instantaneous state of the system
(3) Activity changes of dynamical systems can be described by attractor states:
• a trajectory or point in phase space to which the system will converge from a set of initial coordinates
• a nonlinear system may have more than one attractor
Neural circuits and networks can be described as nonlinear dynamical systems
What are the 3 nonlinear systems?
(1) Instability
Dynamical systems operate near instability:
• respond rapidly with a large, flexible repertoire of sensory and motor patterns
• rapid response is important for animal behaviour (eg avoiding predators)
(2) Phase space
Dynamical systems can be described in a phase space:
• a mathematical space with independent coordinates representing the dynamic variables needed to specify the instantaneous state of the system
(3) Activity changes of dynamical systems can be described by attractor states:
• a trajectory or point in phase space to which the system will converge from a set of initial coordinates
• a nonlinear system may have more than one attractor
What is the Lorenz attractor?
a very specific form of an attractor and its description in phase space
(makes a butterfly winged shape)
TOPIC 2: Applied computational neuroscience
Action selection in health and disease
What are the two most important pathways of the basal ganglia?
direct and indirect pathway
Explain the direct pathway in more detail?
The direct connection is by GABAergic inhibitory interneurons. These interneurons also express the dopamine receptor, D1.
(a) from the stratum to the
(b) GPi/SNr (substantia nigra pars reticulata)
(c) to the thalamus
Explain the indirect pathway in more detail?
the input nuclei striatum and the output nuclei GPi and SNr are not directly connected, it’s indirect.
(a) striatum (GABA)
(b) to the GPE (globus pallidus external segment) (GABA)
(c) STN ( subthalamic nucleus) (Glutamate, excitatory to the
(d) output nuclei GPi and SNr
Both the direct and indirect pathways are gateways to the?
associative and sensory motor cortex, which then coordinates behavioural output
explain the 3 steps of Optogenetics?
- light sensitive proteins are expressed in targeted neurons
- fibre optic cable plus electrode are implanted in the brain
- light activates the targeted neuron
activity in the D1 (direct) pathway facilitates what?
movement
activity in the D2 (indirect) pathway terminates what?
movement
D1 and D2 pathways work together to manage a directed movement.
true or false?
TRUE
Why is it important to have coordinated activity between the direct and indirect pathways?
Impaired action selection may lead to Dyskinesia Motor neuron disease (MND) Parkinson’s disease (PD) Frontotemporal dementia (FTD)
Basal ganglia dysfunction. What are the pathological manifestations?
- motor abnormalities
- impaired memory formation
- attention deficits
- affective disorders
- sleep disturbances
Name a few Basal ganglia-related disorders?
• Parkinson’s disease • Huntington’s disease • dystonia • abulia • dementia • Tourette’s • attention deficit hyperactivity disorder • obsessive-compulsive disorder • depression • schizophrenia
What is Parkinson’s disease?
Dysfunction and loss of nigrostriatal pathway
What are the symptoms of PD?
Symptoms: • tremor • rigidity • bradykinesia - motor and non-motor symptoms
Explain the Behavioural manifestations regulated by neuronal activity of vertebrate basal ganglia and insect central complex?
Basal ganglia: Vertebrate
Striatum, globus pallidus subthalamic nucleus, substantia nigra Postural muscle tone Coordinated locomotion Goal-directed movement Saccadic eye movement Visual orientation and space integration Sleep Arousal Attention Sensorimotor learning Habit learning Reward-seeking behaviour Emotional expression
Central complex: Insect
Protocerebral bridge, fan-shaped body, ellipsoid body, lateral accessory lobe Coordinated locomotion Goal-directed movement Visual orientation and space integration Sleep Arousal Attention Courtship behaviour Place memory Reward-seeking behaviour
What is the common denominator between behaviours?
shared action selections
Does the insect central complex have an direct and indirect pathway like the vertebrate?
No, only a direct pathway (GABAergic)
The ellipsoid body ring neurons and especially the central complex are involved in what? 6 things
higher motor control
visual short-term memory and place learning
direction selective orientation tuning
landmark orientation and angular path integration
attention and arousal
Decision making
These behaviours are controlled by the same neural network, which is involved in the regulation of?
Action selections
the three core functions of R-neurons implementing action selection in the central complex?
Salience detection, switching and activity maintenance
Part 3
Similarities between the basal ganglia and the insect central complex
It is the loss of what pathway, that characterises this kind of Parkinsonism in Drosophila?
the dEB/LAL pathway
Despite the differences in size and composition between the basal ganglia and the insect central complex, there are underlying similarities in their neuromechanisms and computations.
True or false?
TRUE
Facilitation, inhibition, and disinhibition of activities and their intricate interplay enables what?
directed actions
Spatially organised parallel-projecting loops integrate and convey sensorimotor representations that?
select and maintain behavioural activity
Topic 3: The future within reach: Brain-machine interface in neuro-prosthetics
Define neuroprosthetics?
a neuroprosthetic is a device that supplants or supplements the input/output of the nervous system.
Explain a spinal cord injury (SCI) in more detail?
a damage to any part of the spinal cord or nerves at the end of the spinal canal that can lead to changes in strength, mobility and sensations.
With spinal cord injury the sooner treatments are implemented, the better the prognosis.
true or false?
true
What are 4 current recovery strategies after SCI?
Physical therapy
Surgery
Steroid injections
Stem cells
What are 3 ways in which neuroprosthetic devices can be implanted?
(1) EEG (electroencephalography): most common
Non-invasive method where electrodes are placed on the scalp and brain electrical rhythms are recorded
(2) Electrodes implanted into the brain: For more serious and severe injuries of spinal cord
More invasive, provides a higher resolution measurement
(3) Neuroprostheses can be used in other areas of the body:
Eg through implementation in the sacral nerve to treat bladder dysfunction
What is a limitation of electrical neuromodulation of spinal circuits?
specifically epidural electrical stimulation (EES)
EES (epidural electrical stimulation) alone was not able to allow severely impaired patients to walk alone
computerised simulations can predict the onset, modulation and strength of motor responses, evoked in leg muscles, when delivering EES in rats
true or false
TRUE
EES activates interneurons and motor neurons directly
true or false?
FALSE
EES activates interneurons and motor neurons indirectly
