The aim of this thesis is the computational study of the electrical field distribution during
transcranial direct current stimulation (tDCS). Initially, the anatomy and the importance of some
brain tissues are mentioned. In the following, the organization of memory, the stages of sleep and
the relationship between sleep and memory are given. The method of transcranial direct current
stimulation is then described. A brief reference to the electromagnetic theory and the computational
techniques, which were used, follow. Finally, the computational models are described. The first is a
simple brain model (stratified model) and two realistic human models of an adult man and an
adult woman, named as Duke and Ella, from the Virtual Population project. The latter are also
studied with dielectric properties corresponding to an older age. The clinical experiment, which is
closely related to the present work, is also mentioned. Finally, the results of all models (percentage
diagrams and pictures of electrical field distribution) are given and discussed. The last
chapter contains the conclusions of the work.
2024 State of Marketing Report – by HubspotMarius Sescu
https://www.hubspot.com/state-of-marketing
· Scaling relationships and proving ROI
· Social media is the place for search, sales, and service
· Authentic influencer partnerships fuel brand growth
· The strongest connections happen via call, click, chat, and camera.
· Time saved with AI leads to more creative work
· Seeking: A single source of truth
· TLDR; Get on social, try AI, and align your systems.
· More human marketing, powered by robots
ChatGPT is a revolutionary addition to the world since its introduction in 2022. A big shift in the sector of information gathering and processing happened because of this chatbot. What is the story of ChatGPT? How is the bot responding to prompts and generating contents? Swipe through these slides prepared by Expeed Software, a web development company regarding the development and technical intricacies of ChatGPT!
The aim of this thesis is the computational study of the electrical field distribution during
transcranial direct current stimulation (tDCS). Initially, the anatomy and the importance of some
brain tissues are mentioned. In the following, the organization of memory, the stages of sleep and
the relationship between sleep and memory are given. The method of transcranial direct current
stimulation is then described. A brief reference to the electromagnetic theory and the computational
techniques, which were used, follow. Finally, the computational models are described. The first is a
simple brain model (stratified model) and two realistic human models of an adult man and an
adult woman, named as Duke and Ella, from the Virtual Population project. The latter are also
studied with dielectric properties corresponding to an older age. The clinical experiment, which is
closely related to the present work, is also mentioned. Finally, the results of all models (percentage
diagrams and pictures of electrical field distribution) are given and discussed. The last
chapter contains the conclusions of the work.
2024 State of Marketing Report – by HubspotMarius Sescu
https://www.hubspot.com/state-of-marketing
· Scaling relationships and proving ROI
· Social media is the place for search, sales, and service
· Authentic influencer partnerships fuel brand growth
· The strongest connections happen via call, click, chat, and camera.
· Time saved with AI leads to more creative work
· Seeking: A single source of truth
· TLDR; Get on social, try AI, and align your systems.
· More human marketing, powered by robots
ChatGPT is a revolutionary addition to the world since its introduction in 2022. A big shift in the sector of information gathering and processing happened because of this chatbot. What is the story of ChatGPT? How is the bot responding to prompts and generating contents? Swipe through these slides prepared by Expeed Software, a web development company regarding the development and technical intricacies of ChatGPT!
Product Design Trends in 2024 | Teenage EngineeringsPixeldarts
The realm of product design is a constantly changing environment where technology and style intersect. Every year introduces fresh challenges and exciting trends that mold the future of this captivating art form. In this piece, we delve into the significant trends set to influence the look and functionality of product design in the year 2024.
How Race, Age and Gender Shape Attitudes Towards Mental HealthThinkNow
Mental health has been in the news quite a bit lately. Dozens of U.S. states are currently suing Meta for contributing to the youth mental health crisis by inserting addictive features into their products, while the U.S. Surgeon General is touring the nation to bring awareness to the growing epidemic of loneliness and isolation. The country has endured periods of low national morale, such as in the 1970s when high inflation and the energy crisis worsened public sentiment following the Vietnam War. The current mood, however, feels different. Gallup recently reported that national mental health is at an all-time low, with few bright spots to lift spirits.
To better understand how Americans are feeling and their attitudes towards mental health in general, ThinkNow conducted a nationally representative quantitative survey of 1,500 respondents and found some interesting differences among ethnic, age and gender groups.
Technology
For example, 52% agree that technology and social media have a negative impact on mental health, but when broken out by race, 61% of Whites felt technology had a negative effect, and only 48% of Hispanics thought it did.
While technology has helped us keep in touch with friends and family in faraway places, it appears to have degraded our ability to connect in person. Staying connected online is a double-edged sword since the same news feed that brings us pictures of the grandkids and fluffy kittens also feeds us news about the wars in Israel and Ukraine, the dysfunction in Washington, the latest mass shooting and the climate crisis.
Hispanics may have a built-in defense against the isolation technology breeds, owing to their large, multigenerational households, strong social support systems, and tendency to use social media to stay connected with relatives abroad.
Age and Gender
When asked how individuals rate their mental health, men rate it higher than women by 11 percentage points, and Baby Boomers rank it highest at 83%, saying it’s good or excellent vs. 57% of Gen Z saying the same.
Gen Z spends the most amount of time on social media, so the notion that social media negatively affects mental health appears to be correlated. Unfortunately, Gen Z is also the generation that’s least comfortable discussing mental health concerns with healthcare professionals. Only 40% of them state they’re comfortable discussing their issues with a professional compared to 60% of Millennials and 65% of Boomers.
Race Affects Attitudes
As seen in previous research conducted by ThinkNow, Asian Americans lag other groups when it comes to awareness of mental health issues. Twenty-four percent of Asian Americans believe that having a mental health issue is a sign of weakness compared to the 16% average for all groups. Asians are also considerably less likely to be aware of mental health services in their communities (42% vs. 55%) and most likely to seek out information on social media (51% vs. 35%).
AI Trends in Creative Operations 2024 by Artwork Flow.pdfmarketingartwork
This article is all about what AI trends will emerge in the field of creative operations in 2024. All the marketers and brand builders should be aware of these trends for their further use and save themselves some time!
A report by thenetworkone and Kurio.
The contributing experts and agencies are (in an alphabetical order): Sylwia Rytel, Social Media Supervisor, 180heartbeats + JUNG v MATT (PL), Sharlene Jenner, Vice President - Director of Engagement Strategy, Abelson Taylor (USA), Alex Casanovas, Digital Director, Atrevia (ES), Dora Beilin, Senior Social Strategist, Barrett Hoffher (USA), Min Seo, Campaign Director, Brand New Agency (KR), Deshé M. Gully, Associate Strategist, Day One Agency (USA), Francesca Trevisan, Strategist, Different (IT), Trevor Crossman, CX and Digital Transformation Director; Olivia Hussey, Strategic Planner; Simi Srinarula, Social Media Manager, The Hallway (AUS), James Hebbert, Managing Director, Hylink (CN / UK), Mundy Álvarez, Planning Director; Pedro Rojas, Social Media Manager; Pancho González, CCO, Inbrax (CH), Oana Oprea, Head of Digital Planning, Jam Session Agency (RO), Amy Bottrill, Social Account Director, Launch (UK), Gaby Arriaga, Founder, Leonardo1452 (MX), Shantesh S Row, Creative Director, Liwa (UAE), Rajesh Mehta, Chief Strategy Officer; Dhruv Gaur, Digital Planning Lead; Leonie Mergulhao, Account Supervisor - Social Media & PR, Medulla (IN), Aurelija Plioplytė, Head of Digital & Social, Not Perfect (LI), Daiana Khaidargaliyeva, Account Manager, Osaka Labs (UK / USA), Stefanie Söhnchen, Vice President Digital, PIABO Communications (DE), Elisabeth Winiartati, Managing Consultant, Head of Global Integrated Communications; Lydia Aprina, Account Manager, Integrated Marketing and Communications; Nita Prabowo, Account Manager, Integrated Marketing and Communications; Okhi, Web Developer, PNTR Group (ID), Kei Obusan, Insights Director; Daffi Ranandi, Insights Manager, Radarr (SG), Gautam Reghunath, Co-founder & CEO, Talented (IN), Donagh Humphreys, Head of Social and Digital Innovation, THINKHOUSE (IRE), Sarah Yim, Strategy Director, Zulu Alpha Kilo (CA).
Trends In Paid Search: Navigating The Digital Landscape In 2024Search Engine Journal
The search marketing landscape is evolving rapidly with new technologies, and professionals, like you, rely on innovative paid search strategies to meet changing demands.
It’s important that you’re ready to implement new strategies in 2024.
Check this out and learn the top trends in paid search advertising that are expected to gain traction, so you can drive higher ROI more efficiently in 2024.
You’ll learn:
- The latest trends in AI and automation, and what this means for an evolving paid search ecosystem.
- New developments in privacy and data regulation.
- Emerging ad formats that are expected to make an impact next year.
Watch Sreekant Lanka from iQuanti and Irina Klein from OneMain Financial as they dive into the future of paid search and explore the trends, strategies, and technologies that will shape the search marketing landscape.
If you’re looking to assess your paid search strategy and design an industry-aligned plan for 2024, then this webinar is for you.
5 Public speaking tips from TED - Visualized summarySpeakerHub
From their humble beginnings in 1984, TED has grown into the world’s most powerful amplifier for speakers and thought-leaders to share their ideas. They have over 2,400 filmed talks (not including the 30,000+ TEDx videos) freely available online, and have hosted over 17,500 events around the world.
With over one billion views in a year, it’s no wonder that so many speakers are looking to TED for ideas on how to share their message more effectively.
The article “5 Public-Speaking Tips TED Gives Its Speakers”, by Carmine Gallo for Forbes, gives speakers five practical ways to connect with their audience, and effectively share their ideas on stage.
Whether you are gearing up to get on a TED stage yourself, or just want to master the skills that so many of their speakers possess, these tips and quotes from Chris Anderson, the TED Talks Curator, will encourage you to make the most impactful impression on your audience.
See the full article and more summaries like this on SpeakerHub here: https://speakerhub.com/blog/5-presentation-tips-ted-gives-its-speakers
See the original article on Forbes here:
http://www.forbes.com/forbes/welcome/?toURL=http://www.forbes.com/sites/carminegallo/2016/05/06/5-public-speaking-tips-ted-gives-its-speakers/&refURL=&referrer=#5c07a8221d9b
ChatGPT and the Future of Work - Clark Boyd Clark Boyd
Everyone is in agreement that ChatGPT (and other generative AI tools) will shape the future of work. Yet there is little consensus on exactly how, when, and to what extent this technology will change our world.
Businesses that extract maximum value from ChatGPT will use it as a collaborative tool for everything from brainstorming to technical maintenance.
For individuals, now is the time to pinpoint the skills the future professional will need to thrive in the AI age.
Check out this presentation to understand what ChatGPT is, how it will shape the future of work, and how you can prepare to take advantage.
A brief introduction to DataScience with explaining of the concepts, algorithms, machine learning, supervised and unsupervised learning, clustering, statistics, data preprocessing, real-world applications etc.
It's part of a Data Science Corner Campaign where I will be discussing the fundamentals of DataScience, AIML, Statistics etc.
Time Management & Productivity - Best PracticesVit Horky
Here's my presentation on by proven best practices how to manage your work time effectively and how to improve your productivity. It includes practical tips and how to use tools such as Slack, Google Apps, Hubspot, Google Calendar, Gmail and others.
The six step guide to practical project managementMindGenius
The six step guide to practical project management
If you think managing projects is too difficult, think again.
We’ve stripped back project management processes to the
basics – to make it quicker and easier, without sacrificing
the vital ingredients for success.
“If you’re looking for some real-world guidance, then The Six Step Guide to Practical Project Management will help.”
Dr Andrew Makar, Tactical Project Management
Unlocking the Power of ChatGPT and AI in Testing - A Real-World Look, present...Applitools
During this webinar, Anand Bagmar demonstrates how AI tools such as ChatGPT can be applied to various stages of the software development life cycle (SDLC) using an eCommerce application case study. Find the on-demand recording and more info at https://applitools.info/b59
Key takeaways:
• Learn how to use ChatGPT to add AI power to your testing and test automation
• Understand the limitations of the technology and where human expertise is crucial
• Gain insight into different AI-based tools
• Adopt AI-based tools to stay relevant and optimize work for developers and testers
* ChatGPT and OpenAI belong to OpenAI, L.L.C.
Product Design Trends in 2024 | Teenage EngineeringsPixeldarts
The realm of product design is a constantly changing environment where technology and style intersect. Every year introduces fresh challenges and exciting trends that mold the future of this captivating art form. In this piece, we delve into the significant trends set to influence the look and functionality of product design in the year 2024.
How Race, Age and Gender Shape Attitudes Towards Mental HealthThinkNow
Mental health has been in the news quite a bit lately. Dozens of U.S. states are currently suing Meta for contributing to the youth mental health crisis by inserting addictive features into their products, while the U.S. Surgeon General is touring the nation to bring awareness to the growing epidemic of loneliness and isolation. The country has endured periods of low national morale, such as in the 1970s when high inflation and the energy crisis worsened public sentiment following the Vietnam War. The current mood, however, feels different. Gallup recently reported that national mental health is at an all-time low, with few bright spots to lift spirits.
To better understand how Americans are feeling and their attitudes towards mental health in general, ThinkNow conducted a nationally representative quantitative survey of 1,500 respondents and found some interesting differences among ethnic, age and gender groups.
Technology
For example, 52% agree that technology and social media have a negative impact on mental health, but when broken out by race, 61% of Whites felt technology had a negative effect, and only 48% of Hispanics thought it did.
While technology has helped us keep in touch with friends and family in faraway places, it appears to have degraded our ability to connect in person. Staying connected online is a double-edged sword since the same news feed that brings us pictures of the grandkids and fluffy kittens also feeds us news about the wars in Israel and Ukraine, the dysfunction in Washington, the latest mass shooting and the climate crisis.
Hispanics may have a built-in defense against the isolation technology breeds, owing to their large, multigenerational households, strong social support systems, and tendency to use social media to stay connected with relatives abroad.
Age and Gender
When asked how individuals rate their mental health, men rate it higher than women by 11 percentage points, and Baby Boomers rank it highest at 83%, saying it’s good or excellent vs. 57% of Gen Z saying the same.
Gen Z spends the most amount of time on social media, so the notion that social media negatively affects mental health appears to be correlated. Unfortunately, Gen Z is also the generation that’s least comfortable discussing mental health concerns with healthcare professionals. Only 40% of them state they’re comfortable discussing their issues with a professional compared to 60% of Millennials and 65% of Boomers.
Race Affects Attitudes
As seen in previous research conducted by ThinkNow, Asian Americans lag other groups when it comes to awareness of mental health issues. Twenty-four percent of Asian Americans believe that having a mental health issue is a sign of weakness compared to the 16% average for all groups. Asians are also considerably less likely to be aware of mental health services in their communities (42% vs. 55%) and most likely to seek out information on social media (51% vs. 35%).
AI Trends in Creative Operations 2024 by Artwork Flow.pdfmarketingartwork
This article is all about what AI trends will emerge in the field of creative operations in 2024. All the marketers and brand builders should be aware of these trends for their further use and save themselves some time!
A report by thenetworkone and Kurio.
The contributing experts and agencies are (in an alphabetical order): Sylwia Rytel, Social Media Supervisor, 180heartbeats + JUNG v MATT (PL), Sharlene Jenner, Vice President - Director of Engagement Strategy, Abelson Taylor (USA), Alex Casanovas, Digital Director, Atrevia (ES), Dora Beilin, Senior Social Strategist, Barrett Hoffher (USA), Min Seo, Campaign Director, Brand New Agency (KR), Deshé M. Gully, Associate Strategist, Day One Agency (USA), Francesca Trevisan, Strategist, Different (IT), Trevor Crossman, CX and Digital Transformation Director; Olivia Hussey, Strategic Planner; Simi Srinarula, Social Media Manager, The Hallway (AUS), James Hebbert, Managing Director, Hylink (CN / UK), Mundy Álvarez, Planning Director; Pedro Rojas, Social Media Manager; Pancho González, CCO, Inbrax (CH), Oana Oprea, Head of Digital Planning, Jam Session Agency (RO), Amy Bottrill, Social Account Director, Launch (UK), Gaby Arriaga, Founder, Leonardo1452 (MX), Shantesh S Row, Creative Director, Liwa (UAE), Rajesh Mehta, Chief Strategy Officer; Dhruv Gaur, Digital Planning Lead; Leonie Mergulhao, Account Supervisor - Social Media & PR, Medulla (IN), Aurelija Plioplytė, Head of Digital & Social, Not Perfect (LI), Daiana Khaidargaliyeva, Account Manager, Osaka Labs (UK / USA), Stefanie Söhnchen, Vice President Digital, PIABO Communications (DE), Elisabeth Winiartati, Managing Consultant, Head of Global Integrated Communications; Lydia Aprina, Account Manager, Integrated Marketing and Communications; Nita Prabowo, Account Manager, Integrated Marketing and Communications; Okhi, Web Developer, PNTR Group (ID), Kei Obusan, Insights Director; Daffi Ranandi, Insights Manager, Radarr (SG), Gautam Reghunath, Co-founder & CEO, Talented (IN), Donagh Humphreys, Head of Social and Digital Innovation, THINKHOUSE (IRE), Sarah Yim, Strategy Director, Zulu Alpha Kilo (CA).
Trends In Paid Search: Navigating The Digital Landscape In 2024Search Engine Journal
The search marketing landscape is evolving rapidly with new technologies, and professionals, like you, rely on innovative paid search strategies to meet changing demands.
It’s important that you’re ready to implement new strategies in 2024.
Check this out and learn the top trends in paid search advertising that are expected to gain traction, so you can drive higher ROI more efficiently in 2024.
You’ll learn:
- The latest trends in AI and automation, and what this means for an evolving paid search ecosystem.
- New developments in privacy and data regulation.
- Emerging ad formats that are expected to make an impact next year.
Watch Sreekant Lanka from iQuanti and Irina Klein from OneMain Financial as they dive into the future of paid search and explore the trends, strategies, and technologies that will shape the search marketing landscape.
If you’re looking to assess your paid search strategy and design an industry-aligned plan for 2024, then this webinar is for you.
5 Public speaking tips from TED - Visualized summarySpeakerHub
From their humble beginnings in 1984, TED has grown into the world’s most powerful amplifier for speakers and thought-leaders to share their ideas. They have over 2,400 filmed talks (not including the 30,000+ TEDx videos) freely available online, and have hosted over 17,500 events around the world.
With over one billion views in a year, it’s no wonder that so many speakers are looking to TED for ideas on how to share their message more effectively.
The article “5 Public-Speaking Tips TED Gives Its Speakers”, by Carmine Gallo for Forbes, gives speakers five practical ways to connect with their audience, and effectively share their ideas on stage.
Whether you are gearing up to get on a TED stage yourself, or just want to master the skills that so many of their speakers possess, these tips and quotes from Chris Anderson, the TED Talks Curator, will encourage you to make the most impactful impression on your audience.
See the full article and more summaries like this on SpeakerHub here: https://speakerhub.com/blog/5-presentation-tips-ted-gives-its-speakers
See the original article on Forbes here:
http://www.forbes.com/forbes/welcome/?toURL=http://www.forbes.com/sites/carminegallo/2016/05/06/5-public-speaking-tips-ted-gives-its-speakers/&refURL=&referrer=#5c07a8221d9b
ChatGPT and the Future of Work - Clark Boyd Clark Boyd
Everyone is in agreement that ChatGPT (and other generative AI tools) will shape the future of work. Yet there is little consensus on exactly how, when, and to what extent this technology will change our world.
Businesses that extract maximum value from ChatGPT will use it as a collaborative tool for everything from brainstorming to technical maintenance.
For individuals, now is the time to pinpoint the skills the future professional will need to thrive in the AI age.
Check out this presentation to understand what ChatGPT is, how it will shape the future of work, and how you can prepare to take advantage.
A brief introduction to DataScience with explaining of the concepts, algorithms, machine learning, supervised and unsupervised learning, clustering, statistics, data preprocessing, real-world applications etc.
It's part of a Data Science Corner Campaign where I will be discussing the fundamentals of DataScience, AIML, Statistics etc.
Time Management & Productivity - Best PracticesVit Horky
Here's my presentation on by proven best practices how to manage your work time effectively and how to improve your productivity. It includes practical tips and how to use tools such as Slack, Google Apps, Hubspot, Google Calendar, Gmail and others.
The six step guide to practical project managementMindGenius
The six step guide to practical project management
If you think managing projects is too difficult, think again.
We’ve stripped back project management processes to the
basics – to make it quicker and easier, without sacrificing
the vital ingredients for success.
“If you’re looking for some real-world guidance, then The Six Step Guide to Practical Project Management will help.”
Dr Andrew Makar, Tactical Project Management
Unlocking the Power of ChatGPT and AI in Testing - A Real-World Look, present...Applitools
During this webinar, Anand Bagmar demonstrates how AI tools such as ChatGPT can be applied to various stages of the software development life cycle (SDLC) using an eCommerce application case study. Find the on-demand recording and more info at https://applitools.info/b59
Key takeaways:
• Learn how to use ChatGPT to add AI power to your testing and test automation
• Understand the limitations of the technology and where human expertise is crucial
• Gain insight into different AI-based tools
• Adopt AI-based tools to stay relevant and optimize work for developers and testers
* ChatGPT and OpenAI belong to OpenAI, L.L.C.
2. Εγκέφαλος και Μνήμη
Μνήμη Μακράς Διάρκειας
Δεν έχει βρεθεί ξεκάθαρος
μηχανισμός
Εντοπίζεται στον φλοιό (συγκεκριμένο
μέρος δεν έχει βρεθεί)
Μνήμη Βραχείας Διάρκειας
Έχει αναλυθεί ιδίως τα τελευταία
χρόνια ο μηχανισμός
Εντοπίζεται κυρίως στον Ιππόκαμπο
Από μελέτες βρέθηκε ότι η “μνήμη ”
χωρίζεται σε δύο κατηγορίες
Μακράς Διάρκειας
Βραχείας Διάρκειας
1
2
4. Ιππόκαμπος
Μνήμη
(μελέτες σε
ανθρώπους που τους
έχει αφαιρεθεί ο
ιππόκαμπος έδειξαν
αδυναμία
συγκράτησης νέων
πληροφοριών)
Χώρος
(μελέτες με εικόνες
σε ανθρώπους και
μελέτες
προσανατολισμού με
αρουραίους)
1 2
Κύριες
λειτουργίες
6. Οδηγοί ταξί και πλαστικότητα
Αποτελέσματα από αξονική
τομογραφία (MRI scan)
εγκεφάλων στους οδηγούς
ταξί έδειξαν ότι:
Τα 2 οπίσθια
τμήματα του
ιππόκαμπου
ήταν
διογκωμένα
Τα 2 πρόσθια
τμήματα του
ιππόκαμπου
ήταν
συρρικνωμένα
7. Οδηγοί ταξί και πλαστικότητα
Οι αλλαγές που
παρατηρήθηκαν,
πηγάζουν από:
• Αλλαγές στη
γονιδιακή έκφραση
• Αλλαγές στη δομή
και στην
συγκέντρωση των
μορίων
1
Ο παραπάνω
μηχανισμός έχει ως
αποτέλεσμα την
μεταβολή στην ισχύ
της διαβίβασης μιας
σύναψης:
• Ενίσχυση (διευκόλυνση
σύναψης)
• Καταστολή (αποτροπή
σύναψης)
Ενίσχυση/Αποτροπ
ή συνάψεων
μπορεί να είναι:
• Βραχυπρόθεσμη
(διάρκεια
χιλιοστών
δευτερολέπτου)
• Μακροπρόθεσμη
(διάρκεια μέχρι και
30 λεπτά)
2 3
8. LTP (Long-Term Potentiation)
Δημιουργείται από επαναλαμβανόμενα δυναμικά ενέργειας στα προσυναπτικά
κύτταρα, με αποτέλεσμα ενδυνάμωση συναπτικών διασυνδέσεων
Έχει μελετηθεί περισσότερο σε συνάψεις του ιππόκαμπου με
νευροδιαβιβαστή το γλουταμινικό οξύ
Δύο είδη υποδοχέων (AMPA, NMDA)
Συμμετοχή ιόντων (Ca, Mg, Na)
Για την πραγμάτωση του φαινομένου μπορούν να συμβούν αλλαγές στα
προσυναπτικά και μετασυναπτικά κύτταρα
9. LTD (Long-Term Potentiation)
Δημιουργείται από παρατεταμένη διέγερση χαμηλής έντασης, με αποτέλεσμα
αποδυνάμωση συναπτικών διασυνδέσεων
Αναδιαμορφώνει τις συνάψεις ώστε να αποθηκευτούν νέες
πληροφορίες
Δύο είδη υποδοχέων (AMPA, NMDA)
Συμμετοχή ιόντων (Ca, Mg, Na)
12. Σύναψη
1. Αναλλοίωτη μεταφορά δυναμικού
δράσης κατά μήκος του άξονα
2. Απελευθέρωση σήματος στη
συναπτική σχισμή
3. Αλλαγή δυναμικού στο
μετασυναπτικό κύτταρο
13. Νευροδιαβιβαστές
Οι νευροδιαβιβαστές είναι ουσίες οι οποίες απελευθερώνονται από
ένα νευρικό κύτταρο και δρουν ως «ερέθισμα» σε ένα άλλο κύτταρο
«στόχο».
Επιδρούν στα μετασυναπτικά
κύτταρα μεταβάλλοντας την
ηλεκτρική τους δραστηριότητα
(εκπόλωση/υπερπόλωση)
15. Γλουταμινικό οξύ
Είναι ένα πρωτεϊνικό αμινοξύ
Μη «απαραίτητο»
(συντίθεται από γλουταμίνη στα
γλοιακά κύτταρα)
Σημαντικός νευροδιαβιβαστής (συμμετέχει
σε πάνω από τις μισές συνάψεις) που σχετίζεται με
την εγκεφαλική ανάπτυξη, την μάθηση και την
μνήμη
16. Γλουταμινικό ως Νευροδιαβιβαστής
Το γλουταμινικό οξύ χρησιμοποιεί δυο ειδών
μεταφορείς:
EAAT 1-5 (excitatory amino-acid
transporter)
• Μεταφέρει το γλουταμινικό από τη
συναπτική σχισμή και τις
εξωσυναπτικές θέσεις προς γλοιακά
κύτταρα και προσυναπτικούς
νευρώνες
VGLUT 1-3 (vesicular glutamate
transporter)
• Μεταφέρει το γλουταμινικό από το
κυτταρόπλασμα στα συναπτικά
κυστίδια
18. Κύριοι υποδοχείς
Στον ιππόκαμπο παρατηρούνται κυρίως δύο είδη υποδοχέων:
ΥποδοχείςAMPA
i. Ελέγχονται από γλουταμινικό
ii. Λειτουργεί με τυποποιημένο τρόπο
1
2
19. Υποδοχείς NMDA
i. Υποκατηγορία διαύλων
ελεγχόμενων από
γλουταμινικό
ii. Ενεργοποιούνται από τεχνητό
ανάλογο του γλουταμινικού
iii. Διπλά ελεγχόμενοι:
i. Γλουταμινικό στον
υποδοχέα
ii. Μεμβράνη ισχυρά
εκπολωμένη
Κύριοι υποδοχείς
1
2
3
Στον ιππόκαμπο παρατηρούνται κυρίως δύο είδη υποδοχέων:
20. Βασικός κανόνας LTP
LTP συμβαίνει
όταν
Το προσυναπτικό
κύτταρο πυροδοτεί
(μια/περισσότερες
φορές)
Η μετασυναπτική
μεμβράνη είναι ισχυρά
εκπολωμένη (από
πρόσφατη
επαναλαμβανόμενη
πυροδότηση του
προσυναπτικού κυττάρου
ή άλλου μέσου)
1 2
21. Μηχανισμός LTP
Προσυναπτικό
κύτταρο
απελευθερώνει
γλουταμινικό
Υποδοχέας AMPA
ενεργοποιείται και αφήνει
Na+ να εισέλθει στη
μετασυναπτική μεμβράνη
Εκπολώνεται
μετασυναπτική
μεμβράνη
Η εκπόλωση
απομακρύνει
προσδεδεμένο Mg2+ που
παρεμποδίζει το δίαυλο
NMDA
Ca2+ εισέρχεται
από δίαυλο
NMDA
Αύξηση ποσότητας Ca2+
στην μετασυναπτική
μεμβράνη προκαλεί
ενσωμάτωση νέων
υποδοχέων AMPA σε αυτήν
Αύξηση
ευαισθησίας
κυττάρου στο
γλουταμινικό
22. Ρόλος NMDA σε LTP
Όταν παρεμποδίζεται επιλεκτικά (γενετικά/ειδικό
αναστολέα) δεν πραγματοποιείται LTP, αλλά συνεχίζεται
κανονικά η συνήθης συναπτική διαβίβαση.
Ζώα με προβλήματα στον
μηχανισμό παρουσιάζουν ελλείψεις
σε μαθησιακές ικανότητες αλλά
συμπεριφέρονται φυσιολογικά
23. Υποδοχείς NMDA και Ca2+
Χαμηλά επίπεδα Ca2+
• Μέσω ένεσης EGTA, χηλικού παράγοντα
δέσμευσης του Ca2+
• LTP αποτρέπεται
Οι υποδοχείς NMDA είναι ιδιαίτερα διαπερατοί από Ca2+
Υψηλά επίπεδα Ca2+
• Μέσω τεχνητής αύξησης ενδοκυττάριου
Ca2+
• Δέσμευση Ca2+ σε κινάσες, οι οποίες
μεταφέρουν υποδοχείς AMPA και
διευρύνουν τους ήδη υπάρχοντες
• Προκαλείται LTP
Ca2+ είναι ενδοκυττάριος
σηματοδότης που
προκαλεί καταρράκτη από
αντιδράσεις που
ευθύνονται για
πραγματοποίηση LTP
24. Αν οι συνάψεις ήταν ικανές μόνο για
LTP το κύτταρο θα έφτανε σε σημείο
κορεσμού
Άρα πως θα επέλθει η ισορροπία?
25. Μηχανισμός LTD
Προσυναπτικό
κύτταρο
απελευθερώνει
γλουταμινικό
Υποδοχέας AMPA
ενεργοποιείται και αφήνει
Na+ να εισέλθει στη
μετασυναπτική μεμβράνη
Εκπολώνεται
μετασυναπτική
μεμβράνη
Η εκπόλωση
απομακρύνει
προσδεδεμένο Mg2+ που
παρεμποδίζει το δίαυλο
NMDA
Ca2+ εισέρχεται
από δίαυλο
NMDA (μικρή
ποσότητα)
Χαμηλή συγκέντρωση
Ca2+ οδηγεί στην
απομάκρυνση των
υποδοχέωνAMPA
Επαναφορά δυναμικού
μεμβράνης με
αποτέλεσμα την
επαναπρόσδεση Mg2+
στους υποδοχείς NMDA
Μικρότερη εισροή
Na+ στο
μετασυναπτικό
κύτταρο
26. LTD και Ca2+
01
Η μικρή ποσότητα ασβεστίου
ενεργοποιεί μικρή ποσότητα
καλμοδουλίνης
02
03
Αυτή με τη σειρά της
ενεργοποιεί φωσφατάσες
Φωσφατάσες
ΑπομακρύνουνAMPA με
ενδοκυττάρωση
ΑποφωσφορυλιώνουνAMPA, το οποίο οδηγεί στη μείωση της
αγωγιμότητας τους με αποτέλεσμα να υπάρχουν λιγότερα Na+
27. LTD και μνήμη
1
22η θεωρία
1η θεωρία
Το LTD χρησιμοποιείται για διαγραφή υπάρχουσας μνήμης
Το LTD χρησιμοποιείται για τη δημιουργία νέας μνήμης
(ηλεκτρική διέγερση στον εγκέφαλο κατά την διάρκεια μιας νέας εμπειρίας
ενσωματώνεται στην μνήμη η οποία αποθηκεύεται ως LTD των ενεργών
συνάψεων)
28. Πως χάνεται η μνήμη
Γήρανση
i. Εγκεφαλική συρρίκνωση
ii. Μείωση παραγωγής
νευροδιαβιβαστών
Καταστάσεις στρες
29. LTP ή LTD?
Κύριοι παράγοντες που επηρεάζουν
την σηματοδοτική δράση του Ca2+
• Εύρος συχνότητας
• Διάρκεια συχνότητας
• Τοποθεσία/Απόσταση
Η λειτουργία του
Ca2+ εξαρτάται από
τα μόρια που το
προσδένουν
CaMKII – Ca2+
Φωσφορυλιωτικές ενέργειες, που
οδηγούν σε LTP
Calcineurin – Ca2+
Αποφωσφορυλιωτικές ενέργειες, που
οδηγούν σε LTD
1
2
30. Εύρος συχνότητας
Θεωρία
“The two thresholds”
Μέτρια αύξηση συγκέντρωσηςCa2+, οδηγεί σε LTD
Υψηλή αύξηση συγκέντρωσηςCa2+, οδηγεί σε LTP
Επιστημονικές Μελέτες
FDP (Frequency Dependent Plasticity)
STDP (SpikeTiming Dependent Plasticity)
31. Διάρκεια Συχνότητας
Θεωρία
“Low and slow, High and fast”
Αργή και χαμηλή διάρκεια, οδηγεί σε LTD
Γρήγορη και υψηλή διάρκεια, οδηγεί σε LTP
Επιστημονικές Μελέτες
Calcium release manipulation
Εσωτερικοί χώροι αποθήκευσης Ca2+
Υποδοχείς NMDA καιVGCC
i
ii
32. Συνδυασμός 1ης και 2ης θεωρίας
Φωσφατάσες χρειάζονται
“χαμηλά” επίπεδα Ca2+ για LTD
Κινάσες χρειάζονται “υψηλά”
επίπεδα Ca2+ για LTP
“Veto-μηχανισμός” χρειάζεται
“μέτρια” επίπεδα Ca2+ για
παρεμπόδιση LTD
33. Θεωρία
“Micro domains and Nano
domains”
Η τοποθεσία στην οποία γίνεται η απελευθέρωση
Ca2+ καθορίζει την κατεύθυνση της
πλαστικότητας
(διόγκωση/συρρίκνωση)
Επιστημονικές Μελέτες
Εξειδίκευση διαύλων και τοποθεσίας Ca2+
Διαφορετικοί τύποι διαύλων –
διαφορετική τοποθεσία
Ίδιοι τύποι διαύλων – διαφορετική
τοποθεσία
Τοποθεσία/Απόσταση
36. Πηγές - Βιβλιογραφία
3. Maguire, E A et al. “Navigation-related
structural change in the hippocampi of
taxi drivers.” Proceedings of the National
Academy of Sciences of the United States
of America vol. 97,8 (2000): 4398-403.
doi:10.1073/pnas.070039597
4. Παπαθεοδωρόπουλος, Κ. 2015.
Νευροδιαβιβαστές. [Κεφάλαιο
Συγγράμματος]. Στο
Παπαθεοδωρόπουλος, Κ. 2015. Έννοιες
στην επιστήμη της μνήμης. [ηλεκτρ.
βιβλ.] Αθήνα:Σύνδεσμος Ελληνικών
Ακαδημαϊκών Βιβλιοθηκών. κεφ 26.
Διαθέσιμο στο:
(http://hdl.handle.net/11419/3265)
1. Νευρική Πλαστικότητα και Νόηση
(https://www.cognifit.com/el/brain-
plasticity-and-
cognition?fbclid=IwAR3GvOjQXgGivazfb
RCI6zaZ5iIMuwFglhtnYa9w1jL8ufGjPBGr
91Guwyg)
2. Παπαθεοδωρόπουλος, Κ. 2015.
Πλαστικότητα. [Κεφάλαιο
Συγγράμματος]. Στο
Παπαθεοδωρόπουλος, Κ. 2015. Έννοιες
στην επιστήμη της μνήμης. [ηλεκτρ.
βιβλ.] Αθήνα:Σύνδεσμος Ελληνικών
Ακαδημαϊκών Βιβλιοθηκών. κεφ 31.
Διαθέσιμο στο:
(http://hdl.handle.net/11419/3269)
37. Πηγές - Βιβλιογραφία
5. Νευροδιαβιβαστές : Οι χημικοί
αγγελιοφόροι του εγκεφάλου,
Επιστήμες Ζωής, Ηλίας Κανελλόπουλος
(https://eliaskanellopoulos.wordpress.co
m/2011/01/08/νευροδιαβιβαστές-οι-
χημικοί-
αγγελιο/?fbclid=IwAR07X6XhO1bu1WLE
mS1nKojrgREGMLbGKrUG8bH_vecJHr0
WWddFXYJDzw0)
6. Γλουταμινικό οξύ, Σαββούλα Μάλλιου
Κριαρά
(https://www.emedi.gr/διατροφή/item/5
051-γλουταμινικό-
οξύ.html?fbclid=IwAR3GvOjQXgGivazfb
RCI6zaZ5iIMuwFglhtnYa9w1jL8ufGjPBGr
91Guwyg#.XhMZgj7VK01)
7. Διάλεξη 7 Νευροδιαβιβαστές
(Nerotransmitters), Νευροφυσιολογία
και Αισθήσεις, University of Cyprus
Optical Diagnostics Laboratory
(http://www.eng.ucy.ac.cy/cpitris/courses
/ECE471/presentations/Lecture%207.pdf
?fbclid=IwAR1KwziXjTwtjnxmFuvOQx51
4byhkjlSzmBN4DGNwGxYOPxW5w3Du
Mnvo9A)
8. Evans, R C, and KT Blackwell. “Calcium:
amplitude, duration, or location?.” The
Biological bulletin vol. 228,1 (2015): 75-83.
doi:10.1086/BBLv228n1p75
38. Πηγές - Βιβλιογραφία
9. Signal propagation:The movement of
signals between neurons, Khan Academy
(https://www.khanacademy.org/test-
prep/mcat/organ-systems/neural-
synapses/a/signal-propagation-the-
movement-of-signals-between-neurons)
10. The synapse, Khan Academy
(https://www.khanacademy.org/science/biolo
gy/human-biology/neuron-nervous-
system/a/the-synapse)
11. 12.4 Communication Between Neurons,
Anatomy & Physiology, Oregon State
University
(https://open.oregonstate.education/aandp/c
hapter/12-4-communication-between-
neurons/)
12. Lea-Carnall, Caroline A et al. “Evidence
for frequency-dependent cortical
plasticity in the human
brain.” Proceedings of the National
Academy of Sciences of the United States
of America vol. 114,33 (2017): 8871-8876.
doi:10.1073/pnas.1620988114
13. LongTerm Potentiation and Memory
Formation, Animation, Alila Medical
Media
(https://www.youtube.com/watch?v=4H
m08ksPtMo)
14. Long-Term Potentiation and Memory, M.
A. LYNCH, Physiological
Reviews 2004 84:1, 87-136
39. Πηγές - Βιβλιογραφία
15. LongTerm Depression and the
Weakening of Synaptic Strength,
Narrated and Illustrated by George D.
Pollak, Section of Neurobiology,
University ofTexas at Austin
(https://www.youtube.com/watch?v=DM
HbOuqjQ3Y)
16. How memories form and how we lose
them, CatharineYoung,TED-Ed
(https://ed.ted.com/lessons/how-
memories-form-and-how-we-lose-them-
catharine-young)
17. Bear, M F. “Homosynaptic long-term
depression: a mechanism for
memory?.” Proceedings of the National
Academy of Sciences of the United States
of America vol. 96,17 (1999): 9457-8.
doi:10.1073/pnas.96.17.9457
18. Hippocampus, Michael A.Yassa,
Encyclopaedia Britannica, November 18,
2018
(https://www.britannica.com/science/hip
pocampus)
19. Bruce Alberts et al, Molecular Biology of
the Cell, 6th American Edition, 2015,
Chapter 11, “Channels and electrical
properties of membranes”, p. 603-605.
41. Πηγές - Εικόνες
6. Evans, R C, and KT Blackwell. “Calcium:
amplitude, duration, or location?.” The
Biological bulletin vol. 228,1 (2015): 75-83.
doi:10.1086/BBLv228n1p75
7. 12.4 Communication Between Neurons,
Anatomy & Physiology, Oregon State
University
(https://open.oregonstate.education/aan
dp/chapter/12-4-communication-
between-neurons/)
8. Castagnola,Valentina. (2014).
Implantable microelectrodes on soft
substrate with nanostructured active
surface for stimulation and recording of
brain activities.
9. LONG-TERM DEPRESSION,The Brain
FromTopTo Bottom
(https://thebrain.mcgill.ca/flash//i/i_07/i_
07_m/i_07_m_oub/i_07_m_oub.html)
10. Dickie, David & Job, Dominic &
Rodriguez Gonzalez, David & Shenkin,
Susan & Ahearn,Trevor & Murray, Alison
&Wardlaw, Joanna. (2014).Variance in
BrainVolume with Advancing Age:
Implications for Defining the Limits of
Normality. PloS one. 9.
10.1371/annotation/21fb1298-a831-423f-
a247-205641dda40c.
42. Πηγές - Εικόνες
11. Stress – learning and memory killer
(http://spdrdng.com/posts/stress-
learning-and-memory-killer)
12. Brain (http://www.pngall.com/brain-png)
13. AMPA receptor
(https://commons.wikimedia.org/wiki/Fil
e:AMPA_receptor.png)
14. The Lobes ofThe Brain,The Ultimate
Guide to the Brain for AP Psychology
(https://www.albert.io/blog/ultimate-
brain-guide-for-ap-psychology/)
15. Li, Jih-Heng &Vicknasingam, Balasingam
& Cheung,Yuet-Wah & Zhou, Wang &
Nurhidayat, Adhi & Des Jarlais, Don &
Schottenfeld, Richard. (2011).To use or
not to use: an update on licit and illicit
ketamine use. Substance abuse and
rehabilitation. 2. 11-20.
10.2147/SAR.S15458.
16. Huang, Emily & Stevens, Charles. (1998).
The matter of mind: Molecular control of
memory. Essays in biochemistry. 33. 165-
78. 10.1042/bse0330165.
43. Πηγές - Εικόνες
17. Hippocampus, Neuroscientifically
Challenged
(https://www.neuroscientificallychalleng
ed.com/glossary/hippocampus)
18. Explainer: what happens in
the hippocampus?,The Conversation
(http://theconversation.com/explainer-
what-happens-in-the-hippocampus-
32589)