Mark Brandon
London
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Heart always in the ice
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Articles by Mark Brandon
Overlapping representations in the ventral hippocampus support rapid fear memory retrieval
Abstract The dorsal and ventral hippocampus (dCA1 and vCA1) are critical for contextual fear conditioning. The canonical theory states that the hippocampus generates dissimilar context representations to prevent interference and facilitate discrimination between contexts. Here, to test this, we monitored dCA1 and vCA1 context representations as mice were instantaneously transitioned between threatening and neutral contexts.
Author Correction: Predictive coding of reward in the hippocampus
Scott Galloway says skills like computer science and Mandarin are no longer relevant. Here's what kids need instead With the AI boom well underway, tech giants are competing for users to see who can advance the quickest, and the data centers that are being built to …
Author Correction: Predictive coding of reward in the hippocampus
Correction to: Nature https://doi.org/10.1038/s41586-025-09958-0 Published online 14 January 2026 In the version of the article initially published, in Fig. 4b, the colour bar labels “Last” and “First” were switched and have now been corrected so that “Last” is at the pink end and “First” is the blue end. In the third paragraph of the “Pre-reward encoding increases with learning” section, both callouts to Fig. 5 should have been to Fig. 3 and have now been corrected.
Warming substantially amplifies Antarctic coastal polynyas as key carbon sinks
A. S. Studer et al., Increased nutrient supply to the Southern Ocean during the Holocene and its implications for the pre-industrial atmospheric CO2 rise. Nat. Geosci. 11, 756–760 (2018). L. S. Peck, D. K. Barnes, A. J. Cook, A. H. Fleming, A. Clarke, Negative feedback in the cold: Ice retreat produces new carbon sinks in Antarctica. Glob. Change Biol. 16, 2614–2623 (2010). K. I. Ohshima et al., Antarctic bottom water production by intense sea-ice formation in the Cape Darnley polynya. Nat. Geosci. 6, 235–240 (2013). P.
Identifying representational structure in CA1 to benchmark theoretical models of cognitive mapping
Keywords hippocampus CA1 cognitive mapping remapping representational similarity calcium imaging spatial cognition navigation computational modeling place cells Get full text access Log in, subscribe or purchase for full access. References 1. O’Keefe, J. ∙ Nadel, L. The Hippocampus as a Cognitive Map 2. Nieh, E.H. ∙ Schottdorf, M. ∙ Freeman, N.W. ... Geometry of abstract learned knowledge in the hippocampus Nature. 2021; 595:80-84 3. Lee, J.S. ∙ Briguglio, J.J. ∙ Cohen, J.D. ...
Icebergs at the Southern end of Antarctic Sound Mark Brandon
I love looking at satellite images of the Antarctic and picking out the icebergs. In the last few years we have had great stories about the giant icebergs A68 in 2020, A76 in 2022 and most recently A23a currently in the Southern Scotia Sea. At the moment there are two of very large icebergs at the southern end of Antarctic Sound. Here is a map to orientate yourself and show where they are. There is a lot in the image above. As well as the Antarctic Peninsula there are clouds, sea ice, and icebergs.
Medial Entorhinal VIP-expressing interneurons receive direct input from Anterior Dorsal Thalamus and are critical for spatial memory
Abstract Head-direction (HD) cells are found across several regions in the brain, including the anterodorsal thalamic nucleus (ADN), the subicular complex, and the medial entorhinal cortex (MEC). A fundamental role of head direction cells is to provide input to MEC grid cells, which are thought to translate information about head direction into a metric code for spatial location.
Optogenetic silencing of medial septal GABAergic neurons disrupts grid cell spatial and temporal coding in the medial entorhinal cortex
Highlights • Medial septum (MS)-GABAergic inhibition reduces theta rhythms • MS-GABAergic inhibition disrupts grid cell spatial periodicity and theta phase precession • Theta rhythm is restored immediately after MS-GABAergic inhibition • Grid cell spatial coding takes longer (60 s) to recover from MS-GABAergic inhibition Summary The hippocampus and medial entorhinal cortex (MEC) form a cognitive map that facilitates spatial navigation.
Optogenetic Silencing of Medial Septal GABAergic Neurons Disrupts Grid Cell Spatial and Temporal Coding in the Medial Entorhinal Cortex
Abstract The hippocampus and medial entorhinal cortex (MEC) form a cognitive map that facilitates spatial navigation. As part of this map, MEC grid cells fire in a repeating hexagonal pattern across an environment. This grid pattern relies on inputs from the medial septum (MS). The MS, and specifically its GABAergic neurons, are essential for theta rhythm oscillations in the entorhinal-hippocampal network, however, it is unknown if this subpopulation is also essential for grid cell function.
Identifying representational structure in CA1 to benchmark theoretical models of cognitive mapping
Abstract Decades of theoretical and empirical work have suggested the hippocampus instantiates some form of a cognitive map, yet tests of competing theories have been limited in scope and largely qualitative in nature. Here, we develop a novel framework to benchmark model predictions against observed neuronal population dynamics as animals navigate a series of geometrically distinct environments.
Newly formed place cells are stabilized by coordinated population activity during REM sleep.
Abstract The involvement of rapid-eye-movement sleep (REMs) in spatial memory formation was recently demonstrated, although how neural activity during REMs influences newly-formed place field stability remains unclear. Here, we combined large-scale single-unit recordings of mouse hippocampal CA1 with an established optogenetic approach enabling REMs-selective inhibition of medial septum GABAergic neurons (MSGABA), resulting in spatial memory deficits when applied post-learning.
The representation of context in mouse hippocampus is preserved despite neural drift - Nature Communications
Abstract The hippocampus is thought to mediate episodic memory through the instantiation and reinstatement of context-specific cognitive maps. However, recent longitudinal experiments have challenged this view, reporting that most hippocampal cells change their tuning properties over days even in the same environment. Often referred to as neural or representational drift, these dynamics raise questions about the capacity and content of the hippocampal code.
Path integration in normal aging and Alzheimer’s disease
World Health Organization Ageing and Health. Alzheimer’s Association 2021 Alzheimer’s disease facts and figures. Alzheimers Dement. 2021; 17: 327-406 Lester A.W. et al. The aging navigational system. Neuron. 2017; 95: 1019-1035 Mittelstaedt M.-L. Mittelstaedt H. Homing by path integration in a mammal. Naturwissenschaften. 1980; 67: 566-567 Etienne A.S. Jeffery K.J. Path integration in mammals. Hippocampus. 2004; 14: 180-192 Fyhn M. Spatial representation in the entorhinal cortex. Science.
Why Home Workout Equipment Was the Best Move For This Sydney Business
Skip to content May 25, 2020 By Mark Brandon Top Knot Carpentry’s new venture is worth its weight in gold for team morale. With new jobs stalling and productivity down by 30 per cent during the COVID-19 crisis, Sydney company Top Knot Carpentry & Joinery was in a crunch. Forced to reduce their headcount from 750 to 600 staff, they needed a plan to radically reshape. So they paired a love of working out with an expertise in timber manufacturing and a new business was born: Dumbbells By Design.
The IPPC report on the melting ice caps makes for terrifying reading
A Greeland iceberg, 2007. Image: Getty. Earlier this year, the Intergovernmental Panel on Climate Change (IPCC) – the UN body responsible for communicating the science of climate breakdown – released its long-awaited Special Report on the Ocean and Cryosphere in a Changing Climate. Based on almost 7,000 peer-reviewed research articles, the report is a cutting-edge crash course in how human-caused climate breakdown is changing our ice and oceans and what it means for humanity and the living planet.
IPCC report paints catastrophic picture of melting ice and rising sea levels-and reality may be even worse
Greenland’s ice sheet suffered major melting in July 2019, dumping billions of tons of meltwater into the Atlantic Ocean. Credit: Jennifer Latuperisa-Andresen/Unsplash, CC BY-SA The Intergovernmental Panel on Climate Change (IPCC) – the UN body responsible for communicating the science of climate breakdown—has released its long-awaited Special Report on the Ocean and Cryosphere in a Changing Climate.
- Mallemaroking
Greenland’s ice sheet suffered major melting in July 2019, dumping billions of tons of meltwater into the Atlantic Ocena. Jennifer Latuperisa-Andresen/Unsplash, CC BY-SA Mark Brandon, The Open University The Intergovernmental Panel on Climate Change (IPCC) – the UN body responsible for communicating the science of climate breakdown – has released its long-awaited Special Report on the Ocean and Cryosphere in a Changing Climate.
IPCC report paints catastrophic picture of melting ice and rising sea levels - and reality may be even worse
The Intergovernmental Panel on Climate Change (IPCC) – the UN body responsible for communicating the science of climate breakdown – has released its long-awaited Special Report on the Ocean and Cryosphere in a Changing Climate. Based on almost 7,000 peer-reviewed research articles, the report is a cutting-edge crash course in how human-caused climate breakdown is changing our ice and oceans and what it means for humanity and the living planet. In a nutshell, the news isn’t good.
An antarctic storm at sea
As a marine scientist I have always had an obsession with the sea and what it is doing. You can see that by looking at the photos section of this site, or my flickr stream. A couple of weeks ago Dr Ian Brooks (Leeds) tweeted to a colleague, a movie clip of a ship in bad storm. I looked at the video and there was no doubt. It was taken on the RRS James Clark Ross when I was on board.
N113DQ | Airbus A220-100 | Delta Air Lines | Mark Brandon | JetPhotos
Aircraft Airline Country / Airport Photographer / Group Category Keywords Photo year If you are looking for photos of a specific aircraft type, use this menu. Please note that, due to space constraints, this menu includes only some of the more requested aircraft in our database. If the aircraft you're searching for is not in this list, use the 'Keywords' field further down in the search menus. Some menu selections include a generic aircraft model, as well as more specific variants of that airliner.
Hudson Bay is breaking up early
On 25th April 2019, the Arctic sea ice extent was 1.2 million km² below the 1981-2010 mean. Sea ice in the Arctic currently ~1.2 million km² below the 1981-2010 mean. 25 April 2019. If we compare the sea ice extent today, with the mean sea ice extent for the period 1989-93, the red colours show where there is currently relatively low sea ice. The Arctic sea ice extent on 25 April 2019 (LHS), with the mean extent 25 April 1989-93. On the RHS blues = more sea ice than 89-93 mean, reds less sea ice.
Revisiting Antarctic ice loss due to marine ice-cliff instability
Abstract Predictions for sea-level rise this century due to melt from Antarctica range from zero to more than one metre. The highest predictions are driven by the controversial marine ice-cliff instability (MICI) hypothesis, which assumes that coastal ice cliffs can rapidly collapse after ice shelves disintegrate, as a result of surface and sub-shelf melting caused by global warming.
N101DU | Airbus A220-100 | Delta Air Lines | Mark Brandon | JetPhotos
If you are looking for photos of a specific aircraft type, use this menu. Please note that, due to space constraints, this menu includes only some of the more requested aircraft in our database. If the aircraft you're searching for is not in this list, use the 'Keywords' field further down in the search menus. Some menu selections include a generic aircraft model, as well as more specific variants of that airliner. These variants are denoted by a - before the aircraft name.
A trillion tonnes of ice on the move: Iceberg A68A
Just over a year ago in July 2017 iceberg A68 calved from the Larsen C Ice Shelf. I appeared on BBC News before it actually calved explaining what was happening. At first A68 was slow to move and as I predicted back then, it likely got stuck on the sea bed (we say "grounded"). It has stayed pretty much in the same place through to July 2018. But now A68 has started to swing northwards. As the light is coming back to Antarctica, at high latitudes visual imagery is very washed out.
polynya Archives - Mallemaroking
I love watching the opening of a polynya in satellite data. This is North Water at the NW tip of Greenland expanding over 6 days. You can see the wind is to the SW and it is both pushing the mobile sea ice away from the fast ice of Nares Strait (the strait is named for George Nares), and the growth of new sea ice. The Opening of North Water 9-14 May 2018. This is the location of North Water. It is a famous polynya and important for the local wildlife and first peoples.
Hippocampal Neural Circuits Respond to Optogenetic Pacing of Theta Frequencies by Generating Accelerated Oscillation Frequencies
Optogenetic Stimulation of Medial Septal PV Neurons Was Sufficient to Supersede Endogenous Theta Oscillations Septal Control of Theta Oscillations Depended on the Extent of Opsin Expression Theta Frequency Was Controlled by Septal Stimulation while Theta Amplitude Remained Modulated by Running Speed Place Coding by Individual Hippocampal Cells Remained Intact during Optogenetic Pacing of Hippocampal Theta Oscillations The Frequency of Spiking Rhythmicity Partially Scaled with Optogenetically...
Antarctic sea ice growing season - Mallemaroking
The sea ice in the Antarctic is at minimum extent in February and expands through to mid September. This movie shows the Antarctic sea ice extent from 1 Feb to 25 July 2017. The data come from the DMSP SMMI sensor, and it shows the expansion of the sea ice as winter progresses. For me the stand out feature is how late the sea ice expands in the Bellingshausen Sea.
Arctic sea ice 22 July 2017 and the North West Passage - Mallemaroking
I thought it was time to look at the sea ice data as the summer Arctic melt proceeds. The image below shows the mean sea ice extent 1989-93 on 22 July, the sea ice extent 22 July 2017, and the difference between the two data sets. Reds imply less sea ice than the mean 1989-93, and blues an increased sea ice extent. As we would expect, compared with the 1989-93 data the sea ice edge is consistently further north. Things that stand out for me are the virtually open water in the Barents and Kara Seas.
Iceberg A68 is big
Project MIDAS shows us that the iceberg A68 is about one trillion tonnes. This is the Antarctic Peninsula and the outline of A68 from the satellite image on 14 July 2017 shown in black. The ice front is from the Bedmap2 data set (so a little out of date), and the bathymetry from the IBCSO data set. Larsen C Ice shelf on the Antarctic Peninsula and the location and area of iceberg A68. The outline of A68 is derived from a satellite image of the ice shelf 14 July 2017.
Arctic sea ice 13 May 2017 - Mallemaroking
Approaching the middle of May and well into the Arctic sea ice retreat we can see that the sea ice extent (area of ocean with at least 15% sea ice) is still well below the mean over the satellite record. I like a geographic perspective, so this is the mean sea ice extent 1989-93 on 13 May, the sea ice extent 13 May 2017, and the difference between the two data sets. Reds imply less sea ice than the mean 1989-93, and blues an increased sea ice extent.
Joab Jackson's schedule for CloudNativeCon + KubeCon Europe 2017
Joab Jackson TheNewStack Managing Editor
Gavin Schmidt: Climate research where we are
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Sea ice absence January 2017: The Arctic - Mallemaroking
Sea ice continues to be very low in the Arctic this winter. A geographical perspective always helps so here is the status of the sea ice concentration compared with the 1989-1993 mean on the 18 January 2017. RED shades = less sea ice than the 1989-93 mean on 18 January. BLUE shades = more sea ice than the 1989-93 mean on 18 January. A few interesting areas that caught my eye: The first highlight region is the Northern Barents Sea.
Antarctic sea ice 2016: Historic lows - Mallemaroking
The seasonal cycle of sea ice extent in Antarctica has been fairly stable over the length of the satellite record. There is a slow growth of sea ice from a minimum of ~3x106 km2 in February to a maximum of ~19 x106km2 in September, before there is a relatively rapid fall in the Antarctic spring. But this year something different is happening. Below is Tamino's image for the Southern Hemisphere sea ice extent, the red line is 2016 up to 16 November 2016.
The Antarctic 2016 sea ice anomalies - Mallemaroking
The Antarctic 2016 sea ice anomalies This is the the full years data to 21 November for the anomalies of the sea ice extent in 2016. The plot shows the difference between the mean sea ice extent by day for the 5-year period 1989-1993 minus the concentration from that day in 2016. Blue shades imply an increased sea ice extent compared with a 5-year mean, and reds imply a decreased sea ice extent. The five year average sea ice extent (1989-93) - the extent for the same day in 2016.
Record Low Arctic Sea Ice Extent - Mallemaroking
The summer of 2016 saw the joint second lowest Arctic sea ice extent. But in the middle of October unusual Arctic weather has led to it becoming the lowest extent. At the same time, Antarctic sea ice extent has also reached record lows. Tamino has a simple and clear post about what a surprising thing this is. Why is it slow low? The plot below shows the mean November Arctic sea ice extent, the sea ice extent on 16 November 2016, and the difference between the extents from 1993 to 2016.
An Arctic Ocean plankton bloom
The MODIS sensor satellite imagery is showing a beautiful and evolving large plankton bloom in the Chukchi Sea at the moment. The plankton are the lighter green bands I've labelled and the full image is available at an astonishing 250m resolution. If the Bering Straight looks odd it's because this image is taken from over the North Pole and looking southwards.
How are Antarctica's ice shelves changing?
Ask people what they know about Antarctica and they usually mention cold, snow and ice. In fact, there’s so much ice on Antarctica that if it all melted into the ocean, average sea level around the entire world would rise about 200 feet, roughly the height of a 20-story building. Could this happen? There’s evidence that at various times in the past there was much less ice on Antarctica than there is today.
When an Iceberg the Size of a Country Breaks Free, What Happens?
You never forget the first time you see an iceberg. The horizon of a ship at sea is a two dimensional space and to see a three dimensional piece of ice appear in the ocean is quite something. But, in truth, the first iceberg you see is likely to be small. Most icebergs that make it far enough north from Antarctica to where they are danger to shipping are sometimes many years old and at the end of their lives. They are small fragments of what once left the continent.
Destructive 'mega' icebergs breaking off Antarctica
You never forget the first time you see an iceberg. The horizon of a ship at sea is a two dimensional space and to see a three dimensional piece of ice appear in the ocean is quite something. But, in truth, the first iceberg you see is likely to be small. Most icebergs that make it far enough north from Antarctica to where they are danger to shipping are sometimes many years old and at the end of their lives. They are small fragments of what once left the continent.
When an Antarctic Iceberg the Size of a Country Breaks Away, What Happens Next?
You never forget the first time you see an iceberg. The horizon of a ship at sea is a two dimensional space and to see a three dimensional piece of ice appear in the ocean is quite something. But, in truth, the first iceberg you see is likely to be small. Most icebergs that make it far enough north from Antarctica to where they are danger to shipping are sometimes many years old and at the end of their lives. They are small fragments of what once left the continent.
When an Antarctic iceberg the size of a country breaks away, what happens next?
You never forget the first time you see an iceberg. The horizon of a ship at sea is a two dimensional space and to see a three dimensional piece of ice appear in the ocean is quite something. But, in truth, the first iceberg you see is likely to be small. Most icebergs that make it far enough north from Antarctica to where they are danger to shipping are sometimes many years old and at the end of their lives. They are small fragments of what once left the continent.
Sea ice off Southern Greenland
I very much like looking at the AQUA and TERRA MODIS sensor images every now and then. Today I saw this beautiful image off the southern tip of Greenland which was captured on 23rd February 2015. What you are looking at are three different white things: snow on Greenland, clouds and my favorite of course, the sea ice. You may find it hard to pick out the different white features. This is because it is a true colour image.
Polar Leadership: Captain Robert Falcon Scott
Captain Robert Falcon Scott "England knows Scott as a hero; she has little idea of him as a man. He was certainly the most dominating character in our not uninteresting community: indeed, there is no doubt that he would carry weight in any gathering of human beings. But few who knew him realized how shy and reserved the man was, and it was partly for this reason that he so often laid himself open to misunderstanding.
Google Streetview at South Georgia
I do like Google streetview and often use it if I am going somewhere new to see where I am supposed to be heading. So it's really nice to see it at South Georgia in the South Atlantic. The landing page has links to various locations, but I particularly like this one of the grave of Sir Ernest Shackleton. It is a bit clunky as the poor person doing it had to cope with poor weather and moving tourists.
Eaten by the Terror’s cat
The cod icefish re-discovered and published in 1904 by Louis Dollo. The original caption says “Mangé par le chat de l'équipage de la Terror” or “Eaten by the Terror’s cat"! The famous polar ships HMS Erebus and HMS terror had been in the ice long before Franklin took them to their doom in the Northwest Passage. James Clark Ross took them to the Antarctic from 1839-43 on a hugely successful voyage to find the South Magnetic Pole.
Amundsen Sea Embayment | Mallemaroking
-- UPDATED 11 June 2014 -- This post got the dreaded TL; DR on Reddit - but at least "they" acknowledged it was useful. Since it takes someone else to pick out the value in your work I offer this tweet from Jason Major. - ORIGINAL POST A significant area of Antarctic glaciological interest is the West Antarctic Ice Sheet (WAIS) and where it discharges into the Amundsen Sea Embayment. It is a research focus (e.g. iSTAR) because it is the region where the glacier ice is melting very rapidly.
What is a water sky?
I was reading my copy of Nansen's Farthest North the other day and came across a discussion of The Jeannette Expedition which was led by Lt. Cmdr. George DeLong. Nansen wrote I wondered if people knew what a water sky was? This is the American Meteorological Society definition Water Sky - The dark appearance of the underside of a cloud layer when it is over a surface of open water. The picture above which I took in Antarctica tells the story. First look at the lower foreground of the image.
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