Michael Levin Bioelectricity 101 Crash Course Lesson 34: Planarian Memory After Decapitation: Bioelectric Memory Storage Summary
- Planarian flatworms are famous for their remarkable regenerative abilities; they can regrow entire bodies, including their heads and brains, from small fragments.
- Classical neuroscience assumes that long-term memories are stored in the physical structure of the brain (synaptic connections).
- Experiments with planaria demonstrate that learned behaviors (memories) can be retrieved even after the original brain has been completely removed and a new one has regrown.
- This challenges the brain-centric view of memory and suggests that memories can be stored outside the brain, in other tissues of the body.
- Bioelectric networks are a strong candidate for this extra-cerebral (outside the brain) memory storage mechanism.
- Bioelectric circuits can maintain stable patterns of voltage, which could encode information (like a biological “memory”).
- These bioelectric patterns can influence the development of the new brain, guiding it to reconstruct the neural circuits associated with the original memory. This is consistent with Levin’s concepts around how bioelectic “software” programs/provides goals for the genetic “hardware”.
- This is not “memory transfer”; the new brain is built, following body-level electrical and physiological signalling.
- The implications extend far beyond planaria, suggesting new possibilities for understanding memory in other organisms, including humans, and for developing regenerative therapies.
- This demonstrates that the “memories” (consistent patterns across tissues, which can program structure and behaviour), exists as an enduring template within the tissues even during periods where the tissue itself might be vastly different.
Michael Levin Bioelectricity 101 Crash Course Lesson 34: Planarian Memory After Decapitation: Bioelectric Memory Storage
We’ve explored the incredible regenerative abilities of planarian flatworms in previous lessons (Lessons 9, 10, 11, 12, 14, 16, 22, and 34). These masters of regeneration can regrow an entire body, including a complete head and brain, from even a tiny fragment of their original body. This already challenges our intuitive understanding of biology, as it shows that the “blueprint” for the entire organism is somehow stored throughout the body, not just in the head or in a special set of stem cells. But what about memory? What happens to a planarian’s learned experiences when its head – and brain – is removed?
Traditionally, neuroscience has held a very “brain-centric” view of memory. The dominant idea is that long-term memories are encoded in the physical structure of the brain, specifically in the patterns of connections between neurons (synapses). Learning, according to this view, involves strengthening or weakening these connections, creating a physical trace of the experience – an engram. If you destroy the brain, you destroy the memory. This makes intuitive sense; it’s like saying the information on a hard drive is stored in the physical arrangement of magnetic particles. If you smash the hard drive, the information is lost.
But experiments with planaria completely overturn this simple picture. Researchers have trained planaria to perform specific tasks, like associating a light with food or navigating a maze to find a food source. Then, in a truly mind-boggling experiment, they cut off the planarians’ heads, removing their entire brains. The worms, as expected, regrew new heads, including new brains. The astonishing part is that when the regenerated planaria were tested, they remembered the learned behaviors! They still associated the light with food, or they could navigate the maze more quickly than untrained planaria. The original training occurred in a different brain, no longer present in any form.
This is not a minor effect; it’s a fundamental challenge to the standard model of memory. It’s as if you could smash a hard drive, build a completely new one from scratch, and then find that the original data is still somehow accessible. How is this possible?
The answer, increasingly, points to bioelectricity as a crucial player in a more distributed, body-wide memory system. Here’s how it might work:
- Learning and Bioelectric Patterns: When a planarian learns something, it’s not just changing the connections between neurons in its brain. It’s also likely altering the bioelectric state of its tissues. As we’ve learned, cells communicate using electrical signals, and these signals can form stable, persistent patterns. These patterns could represent a kind of “memory” of the learned experience.
- Bioelectric Circuits as Memory Storage: Imagine a complex electronic circuit. The circuit’s behavior isn’t just determined by the presence of components (resistors, capacitors, transistors), but also by how those components are connected and by the electrical state of the circuit (voltages and currents). Similarly, a bioelectric circuit – a network of cells communicating through ion channels and gap junctions – could store information in its pattern of electrical activity. This is analogous to memory in a computer, where a stable distribution of electrical potentials in solid-state non-volatile media.
- Regeneration and Bioelectric Guidance: When a planarian’s head is removed, the remaining body fragment still contains this bioelectric “memory.” It’s not stored in the brain anymore, but it’s present in the other cells of the body, in their membrane potentials and gap junction connections. When regeneration begins, this bioelectric pattern acts as a kind of “template” or “blueprint”, guiding the growth and development of the new brain.
- Reconstructing Neural Circuits: The bioelectric pattern doesn’t directly “transfer” the memory to the new brain. Instead, it influences how the new neurons connect to each other. It guides the formation of the same neural circuits that were associated with the original memory. It’s like having a set of instructions that tells the construction workers how to rebuild the smashed hard drive in a way that preserves the original data. This is critical: bioelectricity is proposed not to literally be “memory transfer”, but to serve to bias/affect what otherwise “randomly” forming brain tissue connects.
This model is still under investigation, but it’s supported by several lines of evidence:
- Bioelectric Manipulations Affect Memory: Experiments have shown that altering the bioelectric state of planaria can interfere with their memory, even without removing their heads. This suggests that bioelectricity is directly involved in memory storage and retrieval.
- Gap Junctions are Crucial: Gap junctions, which allow direct electrical communication between cells, are essential for planarian regeneration and for the retrieval of memory after decapitation. Blocking gap junctions disrupts both processes.
- Modeling Bioelectric Networks: Computational models of bioelectric networks have shown that these networks can indeed store information in stable patterns of voltage. These models provide a theoretical framework for understanding how bioelectricity could function as a memory system.
The implications of this research are profound:
- Memory is More Distributed Than We Thought: It suggests that memories might not be solely located in the brain, but could be distributed throughout the body, in the bioelectric networks of tissues.
- New Avenues for Regenerative Medicine: Understanding how bioelectricity guides regeneration and memory retrieval could lead to new therapies for brain injuries and neurodegenerative diseases. If we could learn to “read” and “write” the bioelectric code, we might be able to restore lost memories or promote the regeneration of damaged brain tissue.
- A New Understanding of Learning and Cognition: It suggests that even relatively simple organisms, without complex brains, might have surprisingly sophisticated cognitive abilities, based on bioelectric information processing. This is at the foundation of Levin’s hypothesis of Basal Cognition.
It is vital to emphasize that we are not describing some sort of Lamarckian inheritance. Lamarck hypothesized (incorrectly) that features changed within an adult animal’s lifespan will be directly inherited and influence their genetically-based characteristics. Rather, this describes an electrophysiolgical model, that represents “memory” outside of brains. This kind of data/patterning does not modify genetics (genes) and does not represent evolution in action.
It’s important to note that this research is still in its early stages. We don’t yet fully understand the details of how bioelectric patterns encode memories or how they guide the reconstruction of neural circuits. But the planarian experiments provide compelling evidence that bioelectricity is a crucial player in a more distributed and dynamic memory system than previously imagined. This work is shifting, with empirical, the prior belief-models into newer, deeper understandings. It’s opening up a whole new frontier in our understanding of memory, learning, and the remarkable regenerative abilities of life.
Michael Levin Bioelectricity 101 Crash Course Lesson 34: Planarian Memory After Decapitation: Bioelectric Memory Storage Quiz
1. What is the traditional, “brain-centric” view of memory storage?
A) Memories are stored in the DNA of cells.
B) Memories are stored in the physical structure of the brain, specifically in synaptic connections.
C) Memories are stored in the bioelectric patterns of the body.
D) Memories are stored in the chemical gradients of the body.
2. What happens to a planarian’s learned behaviors after its head (and brain) is removed?
A) The memories are permanently lost.
B) The planarian can sometimes retrieve the memories after regenerating a new head.
C) The planarian immediately learns new behaviors.
D) The planarian becomes paralyzed.
3. What is the proposed role of bioelectricity in planarian memory retrieval after decapitation?
A) Bioelectric signals directly transfer memories from the old brain to the new brain.
B) Bioelectricity plays a very minor supporting role, compared to chemical changes.
B) Bioelectric patterns in the remaining body tissues store information about the learned behaviors and guide the development of the new brain.
C) Bioelectricity is not involved in planarian memory.
D) Bioelectricity only affects motor skills.
4. What is a key component of cells required for this to be possible?
A) A complex and large neuron-based brain.
B) That it has a spinal chord.
C) Electrical connectivity across tissues and gap junctions
D) Chemical memories.
5. What are gap junctions?
A) Spaces between neurons where neurotransmitters are released.
B) Direct channels connecting the cytoplasm of adjacent cells.
C) Proteins that form the cytoskeleton.
D) Specialized structures in the brain that store memories.
6. True or False: The bioelectric model of memory suggests that memories are solely located in the brain.
A) True
B) False
7. What kind of computational model can be created to represent this storage?
A) Action potential models, representing spikes
B) Chemical-only model, and associated gradients.
C) Electronic-like circuit diagrams, which represents activity flow.
D) Very complex genetic analysis tools.
8. What evidence supports the involvement of bioelectricity in planarian memory?
A) Manipulating bioelectric signals can affect memory, even without head removal.
B) Blocking gap junctions disrupts regeneration and memory retrieval.
C) Computational models show that bioelectric networks can store information.
D) All of the above.
9. What role is the actual planarian doing, physically, after its head is cut off?
A) Nothing, as it is dead
B) Moving chemicals around, but it has very little electrical component to its biology
C) Growing back, and regenerating it’s whole self.
D) Slowly diminishing to eventual starvation.
10. Which describes how the planarian has memories after having regrown it’s head:
A) It had two brains originally, it only loses one upon the cut, and uses it’s second brain still.
B) Magic!
C) “Bioelectric networks maintain stable patterns, retaining information outside of neural tissues”
D) Bioelectric signals form directly to store behaviour experiences.
11. Which of the following is a potential implication of the planarian memory research?
A) Memories might be more distributed throughout the body than previously thought.
B) New therapies for brain injuries and neurodegenerative diseases might be possible.
C) Even simple organisms might have surprisingly sophisticated cognitive abilities.
D) All of the above.
12. Lamarck, an early evolutionary scholar, believed that:
A) Features learned during the lifespan of a creature would then modify its genetics to influence offspring.
B) Chemical gradients drove the shaping of limbs.
C) Regeneration could replace entire organs, including memories.
D) Evolution worked as later described by Darwin.
13. This experiment by scientists on planarian brains directly showed that memory
A) Can exist independent from neural activity, within genetics
B) Exists only, and within the structure of neurons.
C) Does not involve any part of a biological mechanism
D) Exists within persistent tissue states.
14. Bioelectricity plays a/an _______ in these kinds of “outside of the brain” memory experiments.
A) Irrelevant role
B) Important role.
C) Role that diminishes upon a re-grown brain
D) Chemical role.
15. Planarians use electrical networks in their body
A) To pass thoughts along to eachother
B) Maintain goal representations or desired physiological set-points to guide growth.
C) Directly contain information on all proteins for all growth, requiring no reference to their DNA.
D) Store information for evolution, not covered by Darwin.
16. True/False: It can be possible to grow animals to distinct types of heads without adjusting or editing genes?
A) True
B) False
17. The experimental studies provide the biggest challenge to:
A) Prior beliefs in brain/neural centered methods to account for memories.
B) Explaining basic facts that organisms regenerate
C) Prior beliefs about the capabilities and fundamental physics.
D) Standard chemical gradient biology models
18. It could turn out, as a possible conclusion or finding, given results of these experiements:
A) The genome encodes the “parts list,” while non-neural bioelectricity can guide the large-scale organization.
B) Other parts of body also seem capable of holding information.
C) Very simple organisms, such as planaria, have more basal intelligence that often granted to them.
D) All of the above
19. True/False: The new planarian brain has the memories somehow transferred from it’s prior (original) one:
A) True
B) False
20. Levin proposes that new memories might be created after de-capitation:
A) Magically
B) The original memory circuits are re-created by guidance from persistent bioelectrical signalling templates
C) By way of transfer from the previous body tissues
D) Randomly.
Michael Levin Bioelectricity 101 Crash Course Lesson 34: Planarian Memory After Decapitation: Bioelectric Memory Storage Answer Sheet
1. B
2. B
3. B
4. C
5. B
6. B
7. C
8. D
9. C
10. C
11. D
12. A
13. D
14. B
15. B
16. A
17. A
18. D
19. B
20. B
迈克尔·莱文 生物电 101 速成课程 第34课：涡虫斩首后的记忆：生物电记忆存储 摘要
- 涡虫扁虫以其非凡的再生能力而闻名；它们可以从小碎片中再生出整个身体，包括头部和大脑。
- 经典神经科学认为长期记忆存储在大脑的物理结构中（突触连接）。
- 涡虫实验表明，即使在原始大脑被完全移除并重新生长出新的大脑之后，学习行为（记忆）仍然可以恢复。
- 这挑战了以大脑为中心的记忆观，并表明记忆可以存储在大脑之外，在身体的其他组织中。
- 生物电网络是这种脑外记忆存储机制的有力候选者。
- 生物电回路可以维持稳定的电压模式，这可以编码信息（就像生物“记忆”）。
- 这些生物电模式可以影响新大脑的发育，引导它重建与原始记忆相关的神经回路。 这与 Levin 关于生物电“软件”如何编程/提供基因“硬件”目标的概念是一致的。
- 这不是“记忆转移”； 新的大脑是在身体层面的电生理信号的指导下构建的。
- 其意义远远超出涡虫，为理解包括人类在内的其他生物的记忆以及开发再生疗法提供了新的可能性。
- 这表明“记忆”（跨组织的稳定模式，可以规划结构和行为）作为组织内持久的模板存在，即使在组织本身可能发生巨大变化的时期也是如此。
迈克尔·莱文 生物电 101 速成课程 第34课：涡虫斩首后的记忆：生物电记忆存储
我们在之前的课程中探讨了涡虫扁虫令人难以置信的再生能力（第 9、10、11、12、14、16、22 和 34 课）。 这些再生大师甚至可以从其原始身体的一小块碎片中再生出整个身体，包括完整的头部和大脑。 这已经挑战了我们对生物学的直观理解，因为它表明整个生物体的“蓝图”以某种方式存储在整个身体中，而不仅仅是在头部或一组特殊的干细胞中。 但是记忆呢？ 当涡虫的头部（和大脑）被移除时，它的学习经验会发生什么？
传统上，神经科学对记忆持有一种非常“以大脑为中心”的观点。 主流观点认为，长期记忆编码在大脑的物理结构中，特别是在神经元之间的连接（突触）模式中。 根据这种观点，学习涉及加强或削弱这些连接，从而创建经验的物理痕迹——印迹。 如果你破坏了大脑，你就破坏了记忆。 这很有道理； 这就像说硬盘上的信息存储在磁性颗粒的物理排列中。 如果你砸碎硬盘，信息就会丢失。
但是涡虫的实验完全颠覆了这种简单的图景。 研究人员训练涡虫执行特定任务，例如将光与食物联系起来，或者在迷宫中导航以找到食物来源。 然后，在一个真正令人难以置信的实验中，他们切掉了涡虫的头，移除了它们的整个大脑。 正如预期的那样，蠕虫重新长出了新的头，包括新的大脑。 令人惊讶的是，当对再生的涡虫进行测试时，它们记得学习过的行为！ 它们仍然将光与食物联系起来，或者它们可以比未训练的涡虫更快地在迷宫中导航。最初的培训发生在一个*不同的大脑*中，该大脑已经不复存在。
这不是一个小小的影响； 这是对标准记忆模型的根本挑战。 这就像你可以砸碎一个硬盘，从头开始构建一个完全新的硬盘，然后发现原始数据仍然以某种方式可以访问。 这怎么可能？
越来越多的答案表明，生物电是更分散的全身记忆系统中的关键参与者。 以下是它可能的工作原理：
- 学习和生物电模式： 当涡虫学习某件事时，它不仅仅是改变大脑中神经元之间的连接。 它还可能改变其组织的生物电状态。 正如我们所了解的，细胞使用电信号进行通信，这些信号可以形成稳定的、持久的模式。 这些模式可以代表一种学习经验的“记忆”。
- 作为记忆存储的生物电回路： 想象一个复杂的电子电路。 电路的行为不仅仅取决于组件（电阻器、电容器、晶体管）的存在，还取决于这些组件的连接方式以及电路的电状态（电压和电流）。 类似地，生物电回路——通过离子通道和间隙连接进行通信的细胞网络——可以在其电活动模式中存储信息。 这类似于计算机中的内存，其中固态非易失性介质中的稳定电位分布。
- 再生和生物电引导： 当涡虫的头部被移除时，剩余的身体碎片仍然包含这种生物电“记忆”。 它不再存储在大脑中，而是存在于身体的其他细胞中，存在于它们的膜电位和间隙连接中。 当再生开始时，这种生物电模式充当一种“模板”或“蓝图”，指导新大脑的生长和发育。
- 重建神经回路： 生物电模式不会将记忆直接“转移”到新大脑。 相反，它会影响新神经元相互连接的方式。 它指导形成与原始记忆相关的相同神经回路。 这就像有一组指令告诉建筑工人如何重建被砸碎的硬盘以保留原始数据。 这是关键：生物电被认为不是字面上的“记忆转移”，而是用来偏向/影响原本“随机”形成的大脑组织的连接。
该模型仍在研究中，但它得到了多方面证据的支持：
- 生物电操作会影响记忆： 实验表明，即使不移除头部，改变涡虫的生物电状态也会干扰它们的记忆。 这表明生物电直接参与记忆存储和检索。
- 间隙连接至关重要： 间隙连接允许细胞之间进行直接的电通信，这对于涡虫再生和斩首后记忆的恢复至关重要。 阻断间隙连接会破坏这两个过程。
- 生物电网络建模： 生物电网络的计算模型表明，这些网络确实可以将信息存储在稳定的电压模式中。 这些模型为理解生物电如何作为记忆系统发挥作用提供了一个理论框架。
这项研究的意义深远：
- 记忆比我们想象的更分散： 这表明记忆可能不仅仅位于大脑中，还可能分布在全身，分布在组织的生物电网络中。
- 再生医学的新途径： 了解生物电如何引导再生和记忆恢复可能会为脑损伤和神经退行性疾病带来新的治疗方法。 如果我们能够学会“读取”和“写入”生物电代码，我们也许能够恢复失去的记忆或促进受损脑组织的再生。
- 对学习和认知的重新理解： 这表明，即使是没有复杂大脑的相对简单的生物，也可能具有基于生物电信息处理的惊人的复杂认知能力。这是Levin基础认知假设的基础。
强调我们不是在描述某种拉马克式遗传是很重要的。 拉马克假设（不正确）成年动物生命周期内改变的特征将直接遗传并影响其基于遗传的特征。 相反，这描述了一种电生理模型，代表大脑之外的“记忆”。 这种数据/模式不会修改遗传学（基因），也不代表进化在起作用。
值得注意的是，这项研究仍处于早期阶段。 我们尚未完全了解生物电模式如何编码记忆或它们如何指导神经回路重建的细节。 但涡虫实验提供了令人信服的证据，表明生物电是比以前想象的更分散和动态的记忆系统中的关键参与者。 这项工作正在用经验将先前的信念模型转变为更新、更深入的理解。 它为我们理解记忆、学习和生命非凡的再生能力开辟了一个全新的领域。
迈克尔·莱文 生物电 101 速成课程 第34课：涡虫斩首后的记忆：生物电记忆存储 小测验
1. 传统的、“以大脑为中心”的记忆存储观点是什么？
A) 记忆存储在细胞的 DNA 中。
B) 记忆存储在大脑的物理结构中，特别是突触连接中。
C) 记忆存储在身体的生物电模式中。
D) 记忆存储在身体的化学梯度中。
2. 涡虫的头部（和大脑）被移除后，其学习行为会发生什么？
A) 记忆永久丢失。
B) 涡虫有时可以在再生新头部后恢复记忆。
C) 涡虫立即学习新的行为。
D) 涡虫瘫痪。
3. 生物电在涡虫斩首后记忆恢复中的作用是什么？
A) 生物电信号将记忆从旧大脑直接转移到新大脑。
B) 与化学变化相比，生物电起着非常小的支持作用。
B) 残留身体组织中的生物电模式存储有关学习行为的信息并指导新大脑的发育。
C) 生物电与涡虫记忆无关。
D) 生物电仅影响运动技能。
4. 这可能需要的细胞的关键组成部分是什么？
A) 复杂而庞大的基于神经元的大脑。
B) 它有一条脊髓。
C) 跨组织和间隙连接的电连接性
D) 化学记忆。
5. 什么是间隙连接？
A) 神经元之间释放神经递质的空间。
B) 连接相邻细胞细胞质的直接通道。
C) 形成细胞骨架的蛋白质。
D) 存储记忆的大脑中的特殊结构。
6. 对或错：生物电记忆模型表明记忆仅位于大脑中。
A) 对
B) 错
7. 可以创建什么样的计算模型来表示这种存储？
A) 动作电位模型，代表尖峰
B) 仅化学模型，以及相关的梯度。
C) 类似电子的电路图，代表活动流。
D) 非常复杂的遗传分析工具。
8. 有什么证据支持生物电参与涡虫记忆？
A) 即使不移除头部，操纵生物电信号也会影响记忆。
B) 阻断间隙连接会破坏再生和记忆恢复。
C) 计算模型表明生物电网络可以存储信息。
D) 以上都是。
9. 涡虫的头部被切掉后，它实际上在做什么？
A) 什么都不做，因为它已经死了
B) 四处移动化学物质，但它的生物学中只有很少的电成分
C) 长回来，并再生它的整个自我。
D) 慢慢减少直至最终饿死。
10. 哪个描述了涡虫在重新长出头部后是如何拥有记忆的：
A) 它最初有两个大脑，切掉时只失去一个，并且仍然使用它的第二个大脑。
B) 魔法！
C) “生物电网络保持稳定的模式，将信息保留在神经组织之外”
D) 生物电信号直接形成以存储行为体验。
11. 涡虫记忆研究的潜在含义是什么？
A) 记忆可能比以前认为的更分散在全身。
B) 脑损伤和神经退行性疾病的新疗法可能成为可能。
C) 即使是简单的生物也可能具有惊人的复杂认知能力。
D) 以上都是。
12. 拉马克，一位早期的进化论学者，认为：
A) 在生物的生命周期中习得的特征会改变其遗传以影响后代。
B) 化学梯度驱动四肢的形成。
C) 再生可以取代整个器官，包括记忆。
D) 进化就像达尔文后来描述的那样。
13. 科学家对涡虫大脑的这项实验直接表明记忆
A) 可以独立于神经活动而存在，存在于遗传学中
B) 仅存在于神经元的结构中。
C) 不涉及任何生物机制
D) 存在于持久的组织状态中。
14. 在这些“大脑之外”的记忆实验中，生物电起着_______的作用。
A) 无关紧要的作用
B) 重要作用.
C) 重新生长大脑后会减弱的作用
D) 化学作用。
15. 涡虫在体内使用电网络
A) 互相传递思想
B) 维持目标表示或所需的生理设定点以指导生长.
C) 直接包含所有生长的所有蛋白质的信息，无需参考其 DNA。
D) 存储达尔文未涵盖的进化信息。
16. 对/错：无需调整或编辑基因即可将动物培育成不同类型的头部？
A) 对
B) 错
17. 实验研究对以下方面提出了最大的挑战：
A) 以前关于以大脑/神经为中心的方法来解释记忆的信念。
B) 解释生物再生的基本事实
C) 先前关于能力和基本物理学的信念。
D) 标准化学梯度生物学模型
18. 鉴于这些实验的结果，可能得出的结论或发现是：
A) 基因组编码“零件清单”，而非神经生物电可以指导大规模组织。
B) 身体的其他部位似乎也能够保存信息。
C) 非常简单的生物，例如涡虫，比通常认为的具有更多的基础智力。
D) 以上都是
19. 对/错：新的涡虫大脑以某种方式从其先前（原始）的大脑中转移了记忆：
A) 对
B) 错
20. Levin 提出，斩首后可能会产生新的记忆：
A) 神奇地
B) 原始记忆回路通过持久的生物电信号模板的指导重新创建
C) 通过从先前身体组织的转移
D) 随机地。
迈克尔·莱文 生物电 101 速成课程 第34课：涡虫斩首后的记忆：生物电记忆存储 答案表
1. B
2. B
3. B
4. C
5. B
6. B
7. C
8. D
9. C
10. C
11. D
12. A
13. D
14. B
15. B
16. A
17. A
18. D
19. B
20. B