Cognitive Neuroscience 2.5,2.6,2.7 Flashcards
Research on neural networks
What does neural networks mean?
Groups of neurons or structures that are connected together.
Perception of pain is caused by the activation of a network called what?
Pain matrix
What does the pain matrix consist of?
Number of connected structures that are all involved in the perception of pain
Figure 2.21 show: Pain matrix
- In this figure, we have replaced the names of structures with some of the functions these structures serve. Thus, one area is involved in determining the location of pain and its sensory aspects (described by words like throbbing, prickly and intense); some areas are involved in emotional aspects of pain (described by words such as unpleasant, torturing and frightful); other areas are involved in evaluating the significance of a pain stimulus for ongoing behaviour, directing attention to or away from a painful stimulus, and recording memories of the stimulus.
- All of the structures in this network, working together, determine the nature of the overall experience of pain.
Electroencephalgoram (EEG)
How does it work?
- Non-invasive
- Recorded from the scalp
- suitable to study the synchrony and thereby functional connectivity between certain cortical brain areas.
(ERPS)
Event-related potentials
How does it work?
- derived from the EEG when participants are involved in some kind of (computer) information processing task, providing information about the timing and activation level of different stages of information processing.
- ERPs are also used as an index of the number of items in short-term or working memory or as an index of semantic integration
Whats does EEG record?
summed electrical activity of a great number of cortical neurons
measured from scalp electrodes, which are typically embedded in an electrode cap (see Figure 2.22a).
Amplitude and frequency of the EEG signal that can be seen on the computer screen (see Figure 2.22b) strongly correlate with the general brain state of the participant. For example, when one falls asleep the signal becomes slower in frequency (a decrease in the number of cycles per second) and higher in amplitude.
Wehn EEG is recorded from multiples electrodes, one can calculate at which site on the scalp the EEG shows the same rhythm with same starting point is called what?
Phase coherent
What is assumed with phase-coherent?
assumed that the neural populations underlying these recorded EEG rhythms might literally work together as different parts from one and the same neural network.
In other words, they are functionally synchronized and can therefore be taken as a measure of functional connectivity
Compared with fMRI what does EEG measure?
offer the possibility to go beyond the identification of anatomical areas involved in a particular cognitive function, by showing, on a millisecond-by-millisecond basis, the dynamic interactions and communication between different brain areas.
Advantage of EEG?
emporal information derived from the EEG signal is excellent (i.e., EEG has a high temporal resolution)
Disadvantage of EEG
EEG is not as good as fMRI in providing information about where exactly in the brain the signals are coming from (i.e., EEG has a poor spatial resolution).
Definition of temporal resolution?
Refers to the precision of a measurement with regards to time
Definition of spatial resolution
Refers to the precision of a measurement with regards to place
Errors with using fMRI and EEG methods?
Nevertheless, as many sceptics have pointed out, both fMRI and EEG are “just” correlational methods and are as such not able to directly endorse causal relationships. Indeed, a causal relationship can only be demonstrated by altering neural activity and then observing the psychological or behavioural consequences.
To find out causal relationship e.g scanning
For a long time, due to ethical reasons, such methods could be applied to animal models only, for example, in the form of electrical stimulation or lesion studies.
TMS
Transcranial magnetic stimulation
is what?
TMS is a non-invasive method that can be used to stimulate or inhibit certain brain regions. This is done by placing a magnetic field stimulator, or coil, near the head of a person (see Figure 2.23). The magnetic coil induces electrical currents within the cerebral cortex without any discomfort (Nevler & Ash, 2015).
What can TMS be used for?
ap cognitive functions and to intervene in cognitive processes.
What happens if a single TMS pulse or a short sequence of TMS pulse is applied to a specific cortical region?
the electrical activity of that region is temporarily disrupted.
As such, a “virtual lesion” can be created and the resulting disturbance of a specific task performance can be measured.
What can TMS is able to identify a direct relationship between?
e.g
studied brain region and the behavioural outcome
For example, if a participant’s recall performance drops significantly when TMS is applied to cortical region A while he/she is studying a list of words, then it is evident that region A is crucially involved with some kind of memory storage function.
Advantage TMS
This type of reasoning is also used when studying patients with damage to region A, but with TMS there is the added advantage that a change in recall performance can be observed, as one can compare performance with and without TMS.
Disadvantage TMS
not possible to obtain in retrospect a (baseline) performance measure from a patient while his/her brain was still intact. In addition, it is often difficult to find patients with damage that is restricted to exactly region
Vary timing of TMS
E.G
relation to the hypothesized function of certain brain regions, if it is believed to be involved in memory encoding or memory retrieval. Thus, while fMRI and EEG primarily enable us to study function-brain correlations (and certainly this is also a worthwhile exercise), TMS can bring us one step closer to examining causal relationships between cognitive function and brain structure.
Groups of neurons or structures that are connected together are called
Neural networks
Groups of neurons or structures that are connected together are called neural networks.
Which technique is able to trace the communication pathways among neurons?
diuffision tensor imaging
Diffusion tensor imaging (DTI) is based on detection of how water diffuses along the length of nerve fibres and can be used to trace communication pathways among neurons
