Test 2: lecture 14 Telencephalon Flashcards
5 subdivisions of the telencephalon
neocortex
paleocortex
archicortex
basal ganglia
basal forebrain
lesions in the telencephlaon lead to ___ sided signs
contralateral (other side)
lesions in the telencephalon lead to ___
•blindness, depression, seizures
fissure down the center of the two hemispheres
longitudinal
fissure between the frontal and parietal lobe
central sulcus
ansate sulcus (sheep)
There is a region of underlying white matter consisting of ___that carry axons from individual gyri into and out of the ____, which is the major fiber bundle attaching the telencephalon to the brainstem
corona radiata
internal capsules
•There are white matter ____that connect the two cerebral hemispheres.
commissures
___ is white matter that connects the two lateral hemispheres
corpus callosum [CoC]
____ connects the two temporal lobes of the cerebral hemisphere across the midline
rostral/anterior commissure [AC]
___ connects the pretectal nuclei, mediating the consensual pupillary light reflex
caudal (posterior) commissures [PC]
what ventricles are in the telenchalon?
lateral ventricles
three parts of the basal ganglia
striatum → caudate /putamen [PUT] (input)
globus pallidus [GP] (output)
___participate in complex locomotor behavior and emotions
basal ganglia
____ is important in memory
basal forebrain
3 type of cortex in the telencephalon
neocortex
archicortex
paleocortex
neocortex
frontal, parietal, occipital, and temporal lobes
- Most modern, largest and most developed part of the cortex
- only in mammals; 6 layers
archicortex
Hippocampus
- involved in declarative memory function
- Spatial memory, cognitive map of space
- mood, reward
paleocortex
Olfactory Cortex or piriform lobe
-separated from neocortex by the rhinal fissure
layer 2-3 of the neocortex
to other cortical areas
local circuit, short association, long association
____ layer of the neocortex:
to other cortical areas. local circuit, short association, long associatio
2-3
___ is the input layer of the neocortex
layer 4
___ layer of the neocortex
provides feedback to to subcortical areas
(spinal cord, brainstem, basal ganglia)
layer 5
layer 5 of the neocortex
to subcortical areas
(spinal cord, brainstem, basal ganglia)
layer 6 of the neocortex
feedback to the thalamus
___ layer of the neocortex gives feedback to the thalamus
layer 6
the frontal lobe has what primary receiving area?
motor (M1)
thalamic nucleus VL/VA
the parietal lobe has what primary receiving area?
somatic sensory (S1)
thalamic nucleus VPL/VPM
the occipital lobe has what primary receiving area?
visual (V1)
thalamic nucleus: LGN
the temporal lobe has what primary receiving area?
hearing (A1)
thalamic nucleus MGN
each primary receiving areas are organized
topographically: little body in proportion to input
green: Supplementary motor area, SMA: Premotor area, PMA:
area 6 • Motor Planning
orange: P-T-O Association cortex •Analysis of sensory inputs •Constructs representation of our sensory world
pink: Prefrontal Association cortex: •executive function •Abstract thought •decision making •anticipating consequences of action
what area is for •executive function •Abstract thought •decision making •anticipating consequences of action
prefrontal association cortex
(pink)
Brodmann’s area 4
M1- primary motor cortex- initiation of complex voluntary movement
corticospinal tract
Brodmann’s area 6
Supplementary motor area, SMA: Premotor area, PMA:
Motor Planning
somatotopic organization of the primary motor cortex
Betz cells
found in layer 5 of the neocortex in the primary motor cortex
Origin of the corticospinal tract (upper motor neuron)
•Initiation of complex voluntary movement
- Activity in M1 neurons occurs before and during a voluntary movement.
- Activity encodes force and direction of movement
(the more frequent firing= stronger force. Specific Betz cells for specific movements)
Activity in M1 neurons occurs before and during a____movement.
voluntary
Betz cells
lesions ____ where result in the loss of the ability to make independent finger movements
corticospinal tract
lesions in the corticospinal tract will cause
- Difficulty moving distal limbs – may recover over time
- Loss of ability to make independent finger movements – does not recover
____ are involved in motor planning and send signals to M1
area 6- SMA and PMA
Supplementary motor area, SMA:
Premotor area, PMA:
(get set- signal to get ready to perform a specific task)
two main groups of descending spinal pathways from the brain
lateral pathways
ventromedial pathway
descending lateral pathways are:
coricospinal - distal finger movements
rubrospinal- distal
what are the descending spinal pathways ?
tectospinal
vestibulospinal
pontine reticulospinal
medullary reticulospinal
what do the descending lateral pathways control?
- Voluntary movement of distal musculature
- Under direct cortical control
- Innervate distal musculature
ventromedial pathways control ___ and are under __ control. They innervate __ musculature.
Control of posture, locomotion, orienting and balance
- Under brainstem control
- Innervate axial and proximal musculature
lateral descending pathways control ____ are under ____ control and innervate ___
Voluntary movement of distal musculature
- Under direct cortical control
- Innervate distal musculature
lateral spinal pathway comes from ___ area
brodman’s area 4 in the frontal lobe (primary motor cortex)
corticospinal tract: limbs and detailed finger movement
rubrospinal tract: distal limb muscles
corticobulbar tract
(bulb=brainstem) from the cortex to the brainstem
travels with CST (in the lateral funiculus) and provides UMN innervation to LMNs in cranial nerve motor nuclei
Face, jaw, tongue and throat
corticopontine travel in the cerebral peduncles to the ___
pontine nuclei
orienting reflexes are caused by ___
tectospinal tract (head)
tectobulbar tract (eyes)
come from superior colliculus down the spinal cord in the ventral colliculus to the ventral horn
what spinal tract controls balance?
- *vestibulospinal tract**
medial: bilateral to neck
Lateral: ipsilateral to forelimb and hindlimb
from the vestibular nucleus is the medulla down the ventral funiculus to the ventral horn
what tract controls same side posture and locomotion
Pontine reticulospinal tract: ipsilateral
pontine reticular formation down the ventral medial funiculus to the intermediate zone?
what tract controls bilateral posture and locomotion?
medullary reticulospinal tract: bilateral
UMN signs of lesions
Increased tone (spasticity)
Hyperactive reflexes
Pathological reflexes
(plantar extensor or Babinski)
(upper= more tone)
LMN signs of a lesion
Decreased tone
Hypoactive reflexes
Weakness
Atrophy
Fasciculations
(lower= less tone/weakness)
hyperactive reflexes is a sign of ___ lesion
UMN
____ and ____ act on cerebral cortex through relay nuclei in the thalamus (VL/VA)
Basal ganglia
cerebellum
Basal ganglia and cerebellum act on cerebral cortex through relay nuclei _____ in the thalamus
VL: ventral lateral
VA: ventral anterior
___ is involved in the selection and initiation of willed movements procedural learning
basal ganglia
basal ganglia receives info from ___ and relays it to ____
cortex
VL and VA nucleus of the thalamus and up to the motor cortex to effect descending tracts that are controlling voluntary and involuntary movement
inputs of the basal ganglia
caudate and putamen (striatum
___ is the output of the basal ganglia
globus pallidus (pallidum)
5 parts of the basal ganglia
Striatum: caudate/ putamen
Globus pallidus (pallidum)
Subthalamus
Substantia nigra
involved in the selection and initiation of willed movements procedural learning
direct pathway of the basal ganglia
input from cortex comes to the putamen
this synapses at the globus pallidus
globus pallidus stops inhibiting the VL and VA nuclei in the thalamus.
this allows the thalamus to impact the somatic motor area of the brain to effect UMN of voluntary and involuntary muscle movements
____is tonically active and inhibiting the VL/VA thalamus
Globus pallidus
In the basal ganglia, cortex transiently excites ____
striatum (putamen)
striatum = putamen/caudate
(this leads to the temporary inhibition of the globus pallidus which will allow the VA and VL in the thalamus to send a signal to the Somatic motor area)
Putamen transiently ___globus pallidus
inhibits
what happens when the stiatum is stimulated
globus pallidus, which is always sending turn off signals to the VA/VL nucleus of the thalamus, will turn off. this will allow a signal from the VA/VL to go to the motor cortex
how does damage to substantia nigra effect the basal ganglia?
if dopaminergic cells in the substantia nigra are damaged that means it will be harder to turn off the inhibitory signal from the globus pallidus to the VA/VL in the thalamus
it will be harder to make a movement→ hypokinesis → parkinsons
hypokinesis
if dopaminergic cells in the substantia nigra are damaged that means it will be harder to turn off the inhibitory signal from the globus pallidus to the VA/VL in the thalamus
it will be harder to make a movement→ hypokinesis → parkinsons→ tremor harder to initiate a movement
what happens to the basal ganglia if the subthalamus is damaged
Decreased GP output leads to hyperkinesis e.g., Hemiballismus
- loss of tonic inhibitory output to thalamus, cell loss in subthalamus
subthalamus increases the inhibitory action of the globus pallidus on the VL/VA of the thalamus- if you decrease the action of the subthalamus it will be easier to turn off the globus pallidus → easier to make a movement- too big movements- huntington’s chorea (constant movement)
basal ganglia damage results in :
Disturbances of muscle tone (either hypotonia or hypertonia)
Dyskinesias or abnormal involuntary movements
athetosis (writhing movements)
chorea (brisk, involuntary ‘dance-like’ movements of extremities)
ballismus (wild, flinging movements of the limbs)
Resting tremor (Parkinson’s Disease)
In animals with basal ganglia lesions the most typical disturbance
of motor activity is one of excessive locomotion–constant pacing or
___
hyperkinesia
