Ventral hippocampal shock encoding modulates the expression of trace cued fear
Whoa, there’s a TON in this one and I need to follow up on, but this bit caught me by total surprise:
Contextual fear learning was largely intact, although a subset of animals in each sex were differentially affected by shock-silencing.
Despite the conclusion the authors came to (which of course supported their hypothesis), and despite the fuzziness of definitions across various studies of “memory ability” or “memory performance”, it does not appear that hippocampal volume is related to memory ability. This should be expected, as the hippocampus appears to work mostly as a stream constructor/deconstructor with actual “memory” construction occurring in the surrounding association cortexes (e.g. perirhinal cortex, entorhinal cortex). There’s a stronger (but still kind of weak) relationship between VVIQ results and hippocampal volume which is an interesting follow up point here.
This is laden with cognitive crap, but gives a bit of insight into the hand-off between dorsal and ventral stream evaluation of novel information.
I’ve been tracking ultrasound for imaging and general poking brains with a stick ability for the last year, this gives some hope that the training models we will need in order to deploy fUS stimulation won’t be as rigid as I’d been assuming.
Was ready to write this one off but those are some banging effect sizes. Hrm.
Short- and long-term effects of 3.5–23.0 Tesla ultra-high magnetic fields on mice behaviour
Good god. I really need to get a peek at this setup, the cooling mechanisms have to be bonkers. Interestingly, it reaffirms brains don’t really care about the type or source of stimulation, it views them all agnostically. Focusing the chemicals instead of the circuit is probably going to be one of those “Humans are made out of types of bile” moments for science.
Kind of expected, while dorsal and ventral processes have a hemispherical preference, there’s a pretty good body of evidence which demonstrates task based flexibility. More interesting is that astrocyte response. In a perfect world, all neuron studies would tag GFAP as well.
Hippocampus as a scene constructor/deconstructor, not “memory”.
Decoupling astrocytes in adult mice impairs synaptic plasticity and spatial learning
Astrocytes, not neurons, are the primary units of calculation in brains. Astrocytes fully regulate information flow in a brain and are required to store information.
Hippocampal astrocytes represent navigation space
Saying it again for the people in the back.
Transforming Social Perspectives with Cognitive Maps
Yeah pretty close. The important point they’ve hit upon is that “social” constructs are the same type of interpreted mapped function as place or space. Hello CA2 region.
Neural correlates of repeated retrieval of emotional autobiographical events
Three cheers for replication work! Hooray! Hooray! Hooray! To help translate this “Anterior” is “Dorsal”, “Posterior” is “Ventral”. Repeated retrieval (“PTSD”) or intrusive retrieval likely requires a low activation state in the dorsal hippocampus.
The dorsal and ventral streams are interdependent but distinct streams.
Complementary encoding of spatial information in hippocampal astrocytes
Astrocytes pull data from one end of the synapse, process it, then transmit to the other side. Astrocytes calculate. Neurons transmit.
All salience (“behavioral motivation”) initiates in the brain stem.