Lecture 10 - The Claustrum Flashcards
what does the word “claustrum” mean?
‘hidden away’, or ‘to close/shut’
the claustrum is hidden away as a thin sheet of cells between:
the striatum/putamen and the insula
what percent of cells in the cerebral cortex are part of the claustrum?
<1%
why is it difficult to stimulate the claustrum directly?
it is surrounded by axon white matter fibre tracts which signal between many different regions (so stimulating the claustrum is difficult without stimulating these bundles of axons)
can detect claustrum connections with the cortex
diffusion tensor imaging
the claustrum was found to be the most:
densely connected region (as a function of its volume)
axons from the claustrum were found to connect to:
the most frontal and most posterior parts of the cerebral cortex
the claustrum has the strongest _____ with the frontal cortex
bidirectional communication
region of the brain involved in integrating
association cortex
there is generally weak ______ input to the claustrum
sensory cortex
_____, _____, and _____ cells also project to the claustrum
serotonin, dopamine, acetylcholine
the cortex is responsible for:
sensing the world and is topographically organized into different sensory and motor regions
each sensory/motor cortical region provides input to:
different zones of the claustrum
is it possible for different cortical regions to receive inputs from the claustrum?
yes
claustrum outputs are predominantly:
glutamatergic (they release glutamate and depolarize neurons)
frontal cortical regions receive inputs from the _____, and more posterior regions receive inputs from the ______
dorsal claustrum, ventral claustrum
true or false: species differences exist with respect to the anatomical organization of claustrum-cortex connections
true
in humans, cats, and primates, there is a pronounced connection with areas of the:
visual cortex
in rodents, claustrum connections with pre-motor areas of the frontal cortex are dominant, suggesting:
a role in motor control
claustrum connectivity depends on:
species specific sensory/motor specialization (prefers connectivity to parts of the cortex being used most)
excitatory cells in the claustrum can be classified into how many major subgroups?
two
have low dendritic spines, small dentritic branches, and do not typically fire action potential bursts
type one (non spiny) excitatory cells
have extensive dendrites and fire action potential bursts in response to inputs
type two (spiny) excitatory cells
inhibitory claustrum cells appear to be similar to the cortex and express GABA, with different subtypes such as:
parvalbumin, somatostatin, and vasoactive intestinal polypeptide
overall, the composition of neuron types in the claustrum is:
comparable to the cortex
how do neurons in the claustrum respond to cortical inputs?
- the inputs to the parvalbumin (PV) cells was stronger
- detection of an inhibitory response was found in excitatory cells, with a longer latency after the stimulation (this implies a feedforward inhibitory circuit)
excitation happens _____, whereas inhibiton happens due to _____
directly, the activation of an interneuron
the cortex activates the ______ and inhibits the ______
contralateral claustrum, ipsolateral claustrum
using the claustrum, areas of the frontal cortex can:
modulate the posterior cortex efficiantly
due to the claustrum’s high connectivity, it can serve as a way for:
disconnected cortical regions to communicate
activation of the left frontal anterior cingulate cortex activates the claustrum neurons projecting to:
the right visual cortex
signals from one hemisphere activates the other hemisphere in order to:
let it know what’s happening
can be used to specifically activate claustrum neurons with blue light
optogenetics
an opsin that can be used to increase inward sodium currents in neurons
channelrhodopsin (ChR2)
how can ChR2 be expressed in specific cells?
using an adeno associated virus (AAV) that is coupled to a fluorescent tag (GFP) that shows us where the virus is located
go review slide 190
weeeeeeee
claustrum cells can reduce cortical inhibition by:
inhibiting specific interneurons (decreases the inhibitory response)
the effects of claustrum stimulation is similar to:
spontaneous slow waves (sleepy waves)
slow wave sleep is essential for many functions such as:
learning and memory
claustrum cells are more active during:
sleep than during awake
thought to be consolidated or stabilized during sleep
episodic memories
replay or reactivation of neurons during REM or slow wave sleep have been show to:
participate in memory consolidation
if claustrum cells are active during slow wave sleep, this it is possible that:
this region functions in memory consolidation
how do we test the memory of mice?
by measuring how much time they spend exploring objects/spaces (if they explore something a lot, they likely believe it is new)
activation of the claustrum in mice during slow wave sleep increases:
their exploration of the new, displaced object
claustrum stimulation induces a _____, which help consolidate memories
delta wave
is the claustrum associated with associative learning?
some claustrum neurons start to increase their firing during the conditioned stimulus (see slide 196), indicating that they could be participating in this learned response
lesioning the claustrum slowed down the learning of the:
coditioned stimulus (CS) - conditioned response (CR) relationship
claustrum lesions slowed down associative learning in rabbits by:
4-5 days (instead of showing peak performance on day 3, they were delayed until day 7-8)
the active component in ‘magic mushrooms’ that activates serotonergic 5-HT2a receptors to cause hallucinations, euphoria, and changes in perception
psilocybin
claustrum neurons have a dense expression of:
5-HT2a
what effect does psilocybin have on the prefrontal cortex?
increases spine density (particularly in female mice)
spine density reflects:
excitatory synaptic input
the prefrontal cortex receives dense input from:
the claustrum
what effect does psilocybin have on the claustrum?
decreases claustrum activity
how do the actions of psilocybin on the claustrum explain the increase of cortical activity?
the claustrum facilitates feedforward inhibition on the cortex, thus reduced claustrum activity would reduce the amount of inhibition on the cortex
which major diseases is the claustrum involved in?
1) decreased claustrum/cortical connectivity in Parkinson’s
2) increased/decrease claustrum activity in epilepsy
3) smaller claustrum size in schizophrenia and major depression
a rare condition where a healthy individual presents with epilepsy without a known cause
new onset refractory status epilepticus (NORSE)
new onset refractory status epilepticus (NORSE) is often associated with:
claustrum lesion or hyperintensity
a toxin injected into animal paws in order to induce pain
CFA
pain caused by CFA is associated with a pathological increase in neural firing in the:
anterior cingulate cortex (ACC)
what effect does the claustrum have on the anterior cingulate cortex (ACC)?
supresses ACC activity
activating claustrum-cingulate connections reduces:
pain
