Psychoanalysis in the age of neuroscience -  Neuroscience in a nutshell


December 2019
The brain never rests
Did you always believe that your brain rests while you are sleeping?

As we spend most part of our lives sleeping, it is vital to understand why sleeping is so necessary for the brain. To explain this, brain activity during sleep must be examined. A lot of current studies explore the mechanism involved with the production of sleep/dreams and the process of cognition. From the 50’s onward the discovery of REM/ non-REM sleep lead to increased research in neurophysiology and the anatomic correlation between sleep and dreams. The “resting state”, like sleep/dream, mind wandering, restful state, all share the same circuits associated with non-evocative tasks. The DMN (Default Mode Network) is one of them. I'm going to suggest few new studies that can be helpful to keep us updated about new developments in this topic.

Houldin (2019) [1] writes:  "The function of sleep is a longstanding mystery of the brain. By contrast, the function of resting state networks (RSNs) is one of its most recent mysteries". 

The author outlines three studies involving an evaluation of RSNs, across wakefulness and sleep using an  experimental paradigm in which healthy, non-sleep-deprived participants slept in an MRI scanner, as their brain activity was recorded using simultaneous electroencephalography (EEG)-fMRI. 

The results indicate that:

 a) sleep is supported by much the same RSN structure as wakefulness

b) one of the functions of sleep may be to counterbalance wakefulness by homeostasis

c) the pattern of frequency band representation dynamics reflects the cortical neurophysiological dynamics. 


What does that mean?


The author says “By observing communication changes amongst these networks, we can make use of these known associations to infer what the brain might be doing during sleep”.

More specifically: The first study found that the resting state networks that are consistently identifiable in a waking state are also consistently present during sleep, with no new networks appearing, despite the unique functions of sleep

The second study suggests that the function of deep sleep may be to “reset” brain activity closer towards a baseline pattern, so that the brain might be better prepared for the need to adapt and to create new patterns the following day. 

The third study found that, beyond the activity of the networks themselves, representing the collective activity of billions of neurons, subset neuronal populations appear to largely change their activity according to some predictions. 


A few years ago, in 2011, Rosazza & Minati [2] noted:  

"Functional connectivity can be studied during the performance of active tasks, such as finger tapping or visual stimulation, as well as during resting state, a condition in which the participant is not performing any active task and is simply instructed to remain still, with eyes closed or open while fixating a cross. In fact, it is well known that under resting conditions the brain is engaged in spontaneous activity which is not attributable to specific inputs or to the generation of specific output but is intrinsically originated. The brain under normal physiological conditions is never idle, but always remains neuro-electrically and metabolically active". In the meantime: "Many other brain networks have now been observed at rest, including those involved in vision, hearing, and memory. In each of these cases, the same regions that fire together during tasks seem to hum along together at rest, maintaining a signature of their functional organization. The slow, synchronized oscillations within each network—which are independent of each other—are also remarkably robust, persisting even during sleep and under anaesthesia" [3].


What does it say about the anatomical destination of memory in the dream/sleep?

We know that clinical and brain imaging studies link episodic memory and auto-noetic awareness with activity in several prefrontal brain regions (e.g. the medial, dorsolateral), the visual cortex and the medial temporal lobe-including the hippocampus. Hippocampal regions are especially active when the self-referential quality of the memory task is high. Changes in brain function during REM sleep, especially increased activity in the hippocampal formation and decreased activity in prefrontal regions, are consistent with the view that altered episodic memory functioning, linked to these brain regions contributes to the unique quality of dream experience[4] (Nielsen & Stenstrom, 2005).  

In the online page of Neuroscience News [5], they sum up this topic as follows: "While we sleep, the hippocampus reactivates itself spontaneously by generating activity similar to that while we are awake. It sends information to the cortex, which reacts in turn. This exchange is often followed by a period of silence called a ‘delta wave’, then by rhythmic activity called a ‘sleep spindle’. This is when the cortical circuits reorganize to form stable memories. However, the role of delta waves in the formation of new memories is still a puzzle: why does a period of silence interrupt the sequence of information exchanges between the hippocampus and the cortex, and the functional reorganization of the cortex?".

We know that new information is stored into different types of memories.  Neuroscientists call this - the multiple memory systems.  The model of this system originated from the evidence of a pattern of learning impairment after damage to the mammalian hippocampal system. For many reasons they have proposed a dual-memory theory of memory: hippocampus-dependent and non-hippocampus-dependent, or simply, declarative and non-declarative (procedural) memory. The hippocampus and neocortex, moreover, are the neural structures associated with the temporary and long-term memory storage, respectively. 

"Current memory models maintain that these two brain structures accomplish unique, but interactive, memory functions. Specifically:  most modeling suggests that memories are rapidly acquired during waking experience by the hippocampus, before being later consolidated into the cortex for long-term storage. Sleep has been shown to be critical for the transfer and consolidation of memories in the cortex" suggests Langille J. J. (2019)[6] . During subsequent consolidation periods, it is assumed that this network will make it possible to strengthen and integrate new memories with pre-existing memories in long-term memory storage. Off-line periods, such as sleep, are considered the ideal periods for reproduction, since no new incoming information will interfere with consolidation.  

Todorova & Zugaro (2019)[7] carried out a new study exploring the brain structure involved with deep sleep. Neuroscience news sums up this paper as follows: " Spontaneous reactivations of the hippocampus determine which cortical neurons remain active during the delta waves and reveal transmission of information between the two cerebral structures. In addition, the assemblies activated during the delta waves are formed of neurons that have participated in learning a spatial memory task during the day. Together these elements suggest that these processes are involved in memory consolidation. To demonstrate it, in rats the scientists caused artificial delta waves to isolate either neurons associated with reactivations in the hippocampus, or random neurons".  

Todorova and Zugaro argue:  "Does this isolation of cortical computations play a critical role in memory consolidation? A prediction of this hypothesis is that isolating cortical assemblies by experimental induction of delta waves should trigger memory consolidation, but only if the isolated activity is relevant to the hippocampo-cortical dialogue (partner spikes). We have already shown that triggering delta waves, when endogenous mechanisms fail to do so, can boost memory consolidation provided the delta waves are induced in an appropriate time window". In reporting the results of this study the authors note: "We focused on delta spikes and found that they are not neuronal noise due to imperfect silencing of the cortical mantle. On the contrary, they constitute a common phenomenon potentially implicating all neurons and all delta waves, and they react genuine processing involved in memory consolidation. This also provides a mechanism for the documented but puzzling role of delta waves in memory consolidation: synchronized silence across most of the cortex isolates the network from competing inputs, while a select subpopulation of neurons maintains relevant spike patterns active between epochs of hippocampo-cortical information transfer and epochs of cortical plasticity and network reorganization".

The therapeutic targets for various kinds of memory disorders are quite different. For example, for extreme fear-based memories like phobias, one must target the amygdala; for strong habit-based memories like obsessive–compulsive disorders, one must target the striatum;  for severe forgetfulness, as in Alzheimer’s disease, one must target the hippocampus and adjacent structures. 

One possible implication of these studies on memory consolidation is that traumatic memories  will be stored, remembered or forgotten, according to this hippocampus-cortical information transfer and network reorganization.


Rosa Spagnolo


[1] Houldin, E. (2019). Resting State Network Dynamics Across Wakefulness and Sleep. Electronic Thesis and Dissertation Repository. 6397. https://ir.lib.uwo.ca/etd/6397

[2]    Rosazza C. &Minati L. (2011). Resting-state brain networks: literature review and clinical applications. Neurol. Sci. 32:773–785.  DOI 10.1007/s10072-011-0636-y

[3]Shen, H.,  H. (2015).   Core Concept: Resting-state connectivity. PNAS,  17/112: 46 | 14115–14116 https://www.pnas.org/content/112/46/14115

[4] Nielsen, T., A. & Stenstrom P. (2005). What are the memory sources of dreaming? Nature, Vol. 437|27 October 2005|doi:10.1038/nature04288

[5] CNRS (2019). "A new discovery: How our memories stabilize while we sleep." ScienceDaily. ScienceDaily, 18 October

2019. www.sciencedaily.com/releases/2019/10/191018125514.htm

[6] Langille, J.,J. (2019). Remembering to Forget: A Dual Role for Sleep Oscillations in Memory Consolidation and Forgetting. Front. Cell. Neurosci. 13:71. doi: 10.3389/fncel.2019.00071

[7]Todorova R. & Zugaro, M. (2019). Isolated cortical computations during delta waves support memory consolidation. Science, 2019; 366 (6463): 377 DOI: 10.1126/science.aay0616

 



March 2019
Mapping the brain. A step forward the regional connectivity matrix.

Mapping connections between neurons, from different brain regions, and then drawing an atlas of connectivity  is one of the next challenges for scientists. This challenge was taken upby Professor Partha Mitra, from the RIKEN Center for Brain Science in Japan, who is leading a project to map individual brains onto a common reference atlas, despite their significant individual variation. The study involves the common marmoset (Callithrix jacchus), better for this mapping than both the common mouse and primates (like Macaque), because of its flatter cortexandsmaller brain size, that potentially allow more comprehensive analysis of  neuronal circuitry,furthermoreMarmosets exhibit more developed social behavior (Miller et al., 2016) and vocal communication (Marx, 2016). For many reasons, following the initiative in Europe (HBP- Human Brain Project) and US (BRAIN project), Japan launched the Brain/Minds project as an NHPs (Not Humane Primates) model. Tract-tracing methods are the best way for studying the whole brain, whereas previous studies have been based on literature curation and meta-analysis. Now, for the marmoset, an online database of  more than 140 retrograde tracer injection studies in about 50 cortical areas is available online (http://monash.marmoset.brainarchitecture.org)

All the studies carried out shed light on both qualitative and quantitative aspects of neural connections. That means building up an ideal data set which would contain the position, morphology, synaptic connectivity together with transmitter/receptor identities at each synapse as well as spatial maps of the diffuse neuro-modulatory transmitters and receptors of every neuron.This mapping could have a great importance for the studies on connectivity and its dysfunctions (in depression, schizophrenia, autism) but each mapping - even if comprehensive mapping was performed in one brain- would still not address the problem of individual variation across brains, which would ideally require doing the same detailed map for many brains.

The authors introduce detailed information about how to address biological variation and display the three- dimensional reconstruction by different stages of image acquisition, showing an accurate parcellation of the brain. The registration process permitted brain surface reconstruction (Video 1), three- dimensional visualizations of projections, and virtual cuts in planes of section other than the original coronal sectionsso as to finally create a brain map of the regional  connectivity matrix.

 

For further reading please see: 

A high-throughput neurohistological pipeline for brain-wide mesoscale connectivity mapping of the common marmoset.

Meng K. L. , et. al./ Lin et. Al. (2019). eLife, 8:e40042

DOI: https://doi.org/10.7554/eLife.40042

The video

DOI: https://doi.org/10.7554/eLife.40042.011

 

Rosa Spagnolo



January 2019

Topic 1: Knowledge in Pills
When you surf the web on a neuroscience topic, what will you find first? Everybody seeks information through the internet, psychoanalysts included. Therefore, starting a dialogue between neuroscience and psychoanalysis today means to look through many web proposals. By this fast surfing you gain general information: you look at everything, without going into detail. 

Some surfers spend time going into greater depth and reviewing the concepts "reached" by the internet: most surfers   remain trapped in the network of offers. The "knowledge in pills" feeds many fields, including both neuroscience and psychoanalysis.

Our, question today is: Do you think it is possible to gain new insights from this kind of surfing? Does "viewing" the information by scrolling down a page, really mean "knowledge"? Let's start by visiting the neuroscientific top ten

Top 10 Neuroscience News Stories of 2017
Dec 14, 2017 | by Adam Tozer PhD, Science Writer
https://www.technologynetworks.com/neuroscience/lists/top-10-neuroscience-news-stories-of-2017-295213 

And  the 100 best neuroscience blogs
https://blog.feedspot.com/neuroscience_blogs/

Or the top ten of neuroscience video: A collection of TED Talks (and more) on the topic of Neuroscience
https://www.ted.com/playlists/browse?topics=neuroscience

This heading, neuroscience in a nutshell, will try to navigate among  within the enormous amount a lot of neuroscientific information that invests confronts us every day.  It will  work like be a  function as a scanner, which browses through information, selecting and  offering  presenting web news. 

Any input, suggestion and proposal will be considered. Write us.