One study concluded that humans have five times the information-processing capacity of cetaceans, whom they placed beneath chimps, monkeys, and some birds. But in the same study, horses—with smaller brains than chimps—were found to have five times the number of cortical neurons. Does this mean horses are smarter than chimps? A major confounding factor in these types of comparisons appears to be that every factor is itself quite confounding. Estimating numbers of neurons is a very rough science, so the raw number comparisons are crude. There are lots of different kinds of neurons, and they are arranged in different configurations and proportions in different species. We know all these variations mean something, that they will determine what brains are capable of, but we don’t know yet quite what, or how that might change from one moment to the next in different parts of the brain. There are a lot of assumptions at play, and it can be misleading to extrapolate from one brain to another.
This also applies to comparing cognitive ability. Trying to infer from brains and their structures which animals are “better” at cognition and ranking animal brains in order of “intelligence” is as treacherous as it is tempting. Stan Kuczaj, who spent his lifetime studying the cognition and behavior of different animals, put it bluntly: “We suck at being able to validly measure intelligence in humans. We’re even worse when we try to compare species.” Intelligence is a slippery concept and perhaps unmeasurable. As mentioned earlier, many biologists conceive of it as an animal’s ability to solve problems. But because different animals live in different environments with different problems, you can’t really translate scores of how well their brains perform. A brain attribute is not simply “good” or “bad” for thinking, but rather varies depending on the situation and the thinking that brain needs to undertake. Intelligence is a moving target.
What confounds this dilemma further is that individual animals within a species have varying cognitive abilities. To quote the Yosemite National Park ranger who, when asked why it was proving so hard to make a garbage can that bears couldn’t break into, said, “There is considerable overlap between the intelligence of the smartest bears and the dumbest tourists.”
— In the Mind of a Whale
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Interesting Papers for Week 30, 2023
Adult-born neurons inhibit developmentally-born neurons during spatial learning. Ash, A. M., Regele-Blasco, E., Seib, D. R., Chahley, E., Skelton, P. D., Luikart, B. W., & Snyder, J. S. (2023). Neurobiology of Learning and Memory, 198, 107710.
Behavioral origin of sound-evoked activity in mouse visual cortex. Bimbard, C., Sit, T. P. H., Lebedeva, A., Reddy, C. B., Harris, K. D., & Carandini, M. (2023). Nature Neuroscience, 26(2), 251–258.
Exploration patterns shape cognitive map learning. Brunec, I. K., Nantais, M. M., Sutton, J. E., Epstein, R. A., & Newcombe, N. S. (2023). Cognition, 233, 105360.
Distinct contributions of ventral CA1/amygdala co-activation to the induction and maintenance of synaptic plasticity. Chong, Y. S., Wong, L.-W., Gaunt, J., Lee, Y. J., Goh, C. S., Morris, R. G. M., … Sajikumar, S. (2023). Cerebral Cortex, 33(3), 676–690.
An intrinsic oscillator underlies visual navigation in ants. Clement, L., Schwarz, S., & Wystrach, A. (2023). Current Biology, 33(3), 411-422.e5.
Not so optimal: The evolution of mutual information in potassium voltage-gated channels. Duran-Urriago, A., & Marzen, S. (2023). PLOS ONE, 18(2), e0264424.
Successor-like representation guides the prediction of future events in human visual cortex and hippocampus. Ekman, M., Kusch, S., & de Lange, F. P. (2023). eLife, 12, e78904.
Residual dynamics resolves recurrent contributions to neural computation. Galgali, A. R., Sahani, M., & Mante, V. (2023). Nature Neuroscience, 26(2), 326–338.
Dorsal attention network activity during perceptual organization is distinct in schizophrenia and predictive of cognitive disorganization. Keane, B. P., Krekelberg, B., Mill, R. D., Silverstein, S. M., Thompson, J. L., Serody, M. R., … Cole, M. W. (2023). European Journal of Neuroscience, 57(3), 458–478.
A striatal circuit balances learned fear in the presence and absence of sensory cues. Kintscher, M., Kochubey, O., & Schneggenburger, R. (2023). eLife, 12, e75703.
Hippocampal engram networks for fear memory recruit new synapses and modify pre-existing synapses in vivo. Lee, C., Lee, B. H., Jung, H., Lee, C., Sung, Y., Kim, H., … Kaang, B.-K. (2023). Current Biology, 33(3), 507-516.e3.
Neocortical synaptic engrams for remote contextual memories. Lee, J.-H., Kim, W. Bin, Park, E. H., & Cho, J.-H. (2023). Nature Neuroscience, 26(2), 259–273.
The effect of temporal expectation on the correlations of frontal neural activity with alpha oscillation and sensory-motor latency. Lee, J. (2023). Scientific Reports, 13, 2012.
Describing movement learning using metric learning. Loriette, A., Liu, W., Bevilacqua, F., & Caramiaux, B. (2023). PLOS ONE, 18(2), e0272509.
The geometry of cortical representations of touch in rodents. Nogueira, R., Rodgers, C. C., Bruno, R. M., & Fusi, S. (2023). Nature Neuroscience, 26(2), 239–250.
Contextual and pure time coding for self and other in the hippocampus. Omer, D. B., Las, L., & Ulanovsky, N. (2023). Nature Neuroscience, 26(2), 285–294.
Reshaping the full body illusion through visuo-electro-tactile sensations. Preatoni, G., Dell’Eva, F., Valle, G., Pedrocchi, A., & Raspopovic, S. (2023). PLOS ONE, 18(2), e0280628.
Experiencing sweet taste is associated with an increase in prosocial behavior. Schaefer, M., Kühnel, A., Schweitzer, F., Rumpel, F., & Gärtner, M. (2023). Scientific Reports, 13, 1954.
Cortical encoding of rhythmic kinematic structures in biological motion. Shen, L., Lu, X., Yuan, X., Hu, R., Wang, Y., & Jiang, Y. (2023). NeuroImage, 268, 119893.
Mindful self-focus–an interaction affecting Theory of Mind? Wundrack, R., & Specht, J. (2023). PLOS ONE, 18(2), e0279544.
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Delving Deeper into Neuron Anatomy and Brain Functionality (Part 2)
Welcome back, Tumblr enthusiasts! In Part 1, we took our first steps into the neuron and brain universe. Now, let's journey further into their astonishing anatomy and intricate physiology. 🌌💡
Now that we've dived even deeper into the neuron's inner workings and explored more brain regions, I hope you're as captivated as I am by the wonders of neuroscience. Continue to feed your curiosity and stay tuned for more brainy adventures! 🧠
Neuron Anatomy (Continued)
Myelin Sheath: Wrapped around many axons, this fatty insulating layer is like the neuron's protective armor. It speeds up the transmission of electrical signals by allowing them to "jump" from one gap in the myelin sheath, called the Nodes of Ranvier, to the next. Think of it as a high-speed neural highway.
Schwann Cells and Oligodendrocytes: These specialized cells produce the myelin sheath. In the peripheral nervous system (PNS), Schwann cells individually wrap around axons. In the central nervous system (CNS), oligodendrocytes extend processes to multiple axons, forming myelin sheaths around them.
Sensory and Motor Neurons: Neurons aren't one-size-fits-all; they come in different shapes and sizes. Sensory neurons (afferent) bring sensory information from your body and surroundings to your brain and spinal cord. Motor neurons (efferent) carry commands from the brain and spinal cord to muscles and glands, allowing you to move and react.
Neuron Physiology (Continued)
Neurotransmitters: These chemical messengers are the key to communication between neurons. When an action potential reaches the axon terminals, it triggers the release of neurotransmitters into the synapse. These molecules bind to receptors on the neighboring neuron, initiating or inhibiting a new electrical signal, depending on the neurotransmitter type.
Synaptic Plasticity: Neurons can change the strength of their connections through a phenomenon called synaptic plasticity. This allows us to adapt and learn. Two important types include long-term potentiation (LTP), which strengthens synapses, and long-term depression (LTD), which weakens them.
Brain Functionality (Continued)
Thalamus: Often called the "relay station," the thalamus acts as a switchboard, directing sensory information (except for smell) to the appropriate regions of the cerebral cortex for further processing.
Hypothalamus: This small but mighty structure regulates many essential functions, including hunger, thirst, body temperature, and the body's internal clock (circadian rhythms).
Frontal Cortex: Located in the frontal lobes of the cerebral cortex, this region is responsible for higher cognitive functions like decision-making, planning, reasoning, and personality.
Temporal Lobes: These are crucial for auditory processing and memory. The hippocampus, nestled deep within the temporal lobes, is essential for forming new memories.
References
Purves, D., et al. (2017). "Neuroscience." Sinauer Associates, Inc.
Kandel, E. R., Schwartz, J. H., & Jessell, T. M. (2012). "Principles of Neural Science." McGraw-Hill Education.
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