Cortex Flashcards
Cerebral hemispheres =
a mantle of nervous tissue that overlies the brainstem and is divided at the midline into two mirrored halves.
The deep layers of the cortex contain _________________________________________ that interconnects the various areas of the overlying cortex.
white matter (axons)
The external surface of the cerebral hemispheres is composed of ____________________________________________________ which is convoluted.
gray matter (containing neuronal cell bodies)
On the external surface of the cerebral hemispheres, the crest of a given convolution is called a ______________________.
gyrus (gyri; pl.)
On the external surface of the cerebral hemispheres, a groove or depression in the surface of the cerebral hemispheres is called a ____________________________________.
sulcus (sulci; pl.) or fissure (deepest ones).
The cerebral cortex also has a functional organization which can be most easily demonstrated in the sensorimotor homunculi on either side of the ___________________________.
central sulcus.
Brodmann’s areas: In addition to subdividing the above lobes into gyri and sulci, they may also be subdivided according to the ___________________________ arrangement of the neurons as they are differentially arranged in the various regions of the cortex. Using this criterion, a variety of investigators have attempted to map the cerebral cortex, resulting in classification schemes ranging from 20 cortical areas to more than 200. The most widely referenced classification of cortical areas is that outlined by Brodmann, who identified more than 50 different cortical areas.
cytoarchitectural
Although Brodmann’s areas are primarily based on cytoarchitectural criteria, there is a strong association with discrete functions (taste, vision, primary motor, primary somatosensory, etc.). Although Brodmann’s areas generally follow discrete gyri they frequently overlap one or more gyri, or conversely, there may be ________________________ Brodmann’s area in one gyrus.
more than one
What are 3 functional categories of efferent neurons?
- projection
- association
- commissural
Define projection neurons (function category of efferent neuron):
to subcortical areas; basal ganglia, thalamus, brainstem, spinal cord
Define association neurons (function category of efferent neuron):
connections between areas of cortex in the same hemisphere
Define commissural neurons (function category of efferent neuron):
- connections between areas in different hemispheres (corpus callosum, anterior commissure)
Interhemispheric transfer of information - the two hemispheres are highly interconnected through the ______________________ and the ______________________. Each area of cortex on one side sends axons to the identical area on the other side.
corpus callosum
anterior commissure
What is the importance of hemispheric connectivity?
THIS CONNECTIVITY IS VERY IMPORTANT FOR STORING MEMORY ON BOTH SIDES OF THE BRAIN, FOR COMPARING THE LEFT AND RIGHT HALVES OF THE BODY AND EXTERNAL ENVIRONMENT.
Primary sensory cortices are the regions that first interpret the ___________________________________ information. It is very specific, just “pieces” of the actual perception of that sensation or thought.
Association areas are cortical areas that put the encoded sensation into _______________. Without association areas, the individual stimulus makes little sense.
encoding of sensory
context
Do association areas respond to multiple modalites or just a signle modality?
Association areas can be specific to a single modality or respond to multiple modalities.
Learning and memory - long term memory resides in the ________________but how and where is poorly understood. Latest idea is that memory is parceled out to anatomically separated areas that are close to the ________________ area. For example, the memory of a flower is stored as separate entities of smell, color, feel. There are cortical and _______________areas that are then connected to each of the modality specific association areas which seem to function in laying down the entire memory. These areas also seem to be critical in retrieval of memories, needing only a part of the entire memory to access the entire memory.
cortex
primary cortical
thalamic
Is the whole memory necessary for retrieval of the memory?
NO, retrieval of memories, needing only a part of the entire memory to access the entire memory.
Cerebral dominance and functional representation :
as we mature, one hemisphere or the other takes responsibility for language comprehension and speech.
Hand dominance is correlated with the ______________________.
dominant hemisphere
**but this is not how hemisphere dominance is determined
About 95% of all people are left hemisphere dominant and about 90% of people are right-handed; which is the dominant hemisphere of right handed people?
is controlled by the left hemisphere.
The non-dominant hemisphere appears to specialize in:
nonverbal, non-mathematical domains, functions such as music appreciation, artistic activity and appreciation for the significance of sensory stimuli (should we ignore or pay attention to the stimuli).
What is the dominant hemisphere is defined by?
the presence of language, both the speech component and the comprehensive component
Parts of the inferior frontal gyrus that lie anterior to the face region of precentral gyrus function in the motor part of speech production are known as:
(Broca’s area; Brodmann’s areas 44, 45).
Parts of the parietal lobe and superior temporal gyrus that are located at the caudal tip of the lateral fissure function in the comprehension of language =
(Wernicke’s area; Brodmann’s areas 22, 39)
In most individuals, whether right or left hand dominant, the dominant hemisphere is located in the _______ hemisphere as determined by the presence of language.
left
The non-dominant hemisphere has similar (as the dominant hemisphere) cytoarchitectural areas, but they are involved in:
prosody
What is prosody?
the inflection, emotion, or color components of language, both production and comprehension.
_____________________________ cortex also seems to play a role in language. Experimental stimulation results in vocalization of sustained vowel sounds.
Supplementary motor
Premotor and supplementary motor cortical regions are located in Brodmann’s area __.
6
Premotor cortex, on the lateral surface, receives a majority of the:
thalamocortical projections from VL (cerebellar connections),
Supplementary motor cortex receives a majority of:
thalamocortical projections from VL/VA (basal ganglia connections).
Experimental evidence of these two “premotor” (premotor and supplementary motor) regions indicates a difference in function (explained by extracortical motor circuitry?). Stimulation of lateral premotor region results in movements of____________________________________, while ablation results in loss of ______________________________________________________________________.This is termed _________.
contralateral limb (mostly proximal joints)
interjoint coordination indicating deficits in coordination of timing for each joint.
apraxia
Stimulation of supplementary motor cortex results in _______________________________________________________________________________________. Grasping can be elicited, but not from a fine motor standpoint.
multijoint movements of the extremities and may be displayed bilaterally as postural and proximal joint responses.
When is supplementary motor most active?
the movement is internally generated rather than sensory generated.
Can these “premotor” regions (premotor and supplementary motor) motor responses take place without area 4?
Yes, While these two “premotor” regions (premotor and supplementary motor) send efferents to primary motor cortex, motor responses from both of these regions can take place without area 4.
Both premotor regions (premotor and supplementary motor) contribute fibers to__________________________________________ tracts.
A major component of the efferent pathway from supplementary motor area is to brainstem __________________motor areas, as a component of the ___________________________pathway.
corticospinal and corticobulbar
reticular
corticoreticulospinal pathway
List the motor areas of the frontal lobe:
- primary motor cortex
- supplementary motor area
- lateral premotor area
- frontal eye fields
- vergence eye control
- motor writing center of exner
Broca’s area
What is the broadmans area of primary motor cortex:
precentral gyrus, area 4
What is the broadmans area of supplementary motor area:
midline area 6 rostral to paracentral lobule
What is the broadmans area of lateral premotor area:
area 6
What is the broadmans area of frontal eye fields:
area 8; contains lateral gaze and vertical gaze centers
What is the broadmans area of vergence eye control:
area 8 rostral to frontal eye fields
What is the broadmans area of motor writing center of exner:
area 8
What is the broadmans area of Broca’s area:
44, 45
Prefrontal Cortex consists of the non-motor regions of the frontal lobe and is divided into ________________________________________ regions. These regions are continuous into the ______________________ regions
lateral prefrontal and orbitofrontal regions.
midline cortical regions.
What is the function of the lateral prefrontal cortex?
self-awareness and executive function or goal-oriented behavior.
How can the lateral prefrontal cortex be parceled out?
- deciding on a goal
- planning how to accomplish
- executing the plan
- monitoring the execution of the plan
Orbitofrontal cortex functions :
attaching or interpreting emotion within the context of the situation
Which part of the prefrontal cortex is associated with the limbic system function?
orbitofrontal
Where is the orbitofrontal cortex connectively related closely to?
amygdala
What are 3 functions of the orbitofrontal cortex?
- regulating mood (subjective feelings)
- affect (observable demeanor)
- processing of some types of memory (emotionally charged, fear)
The prefrontal cortex functions as part of the system that is activated by the ___________________________________ to direct ___________________________ to ongoing environment (consciousness), and to choose the best response.
reticular formation
attention (cognition)
The responses from the prefrontal cortex in regards to directing attention to the ongoing EN (consciousness), may be new experiences or response based on retention of past experiences (memory). In doing so, specific neurotransmitter pathways of the reticular system have been associated with specific cortical functions:
- Serotonin
- norephinephrine
- acetylcholine
- dopamine
serotonin =
(raphe nuclei) - generalized arousal level
norepinephrine =
(locus ceruleus) - direction of consciousness
Acetylcholine =
(pedunculopontine nucleus) - selection of object of attention, based upon goals
basal forebrain - general arousal of cortex - loss of cholinergic neurons in this area are implicated in Alzheimer’s disease
Dopamine =
(ventral tegmental area and substantia nigra) - motivation, motor activity, and cognition
There are lateralized differences in the parietal lobe and how the sides function with respect to ______________________.
spatial awareness.
In the parietal lobe, which hemisphere is more dominant?
The right hemisphere is the more dominant (don’t confuse this with dominance of hemisphere; see discussion on language) in terms of understanding the “entire” spatial map as it is interpreted by the proprioceptive and visual systems.
What do damages to the right parietal lobe cause?
Damage to the right parietal lobe has profound consequences in attending to the left side of body and visual space.
What does damage to the left parietal lobe cause?
Damage to the left parietal lobe has only minimal and non-lasting effect on attending to the right side of the body and visual space.
Describe hemineglect:
Neglect (hemineglect) is a phenomenon that is seen following damage to the right parietal lobe. Following damage, patients tend to “ignore” the left side of visual, auditory and body space.
Extinction is a form of ______________________________________________________________________________________________________
However, if the stimulus is presented on both sides simultaneously, it is attended to only on the intact side and “ignored” on the involved side. This can be evoked with visual, tactile or auditory stimuli.
inattention that manifests when a stimulus is attended to on the involved side, contralateral to the parietal lobe lesion.
What is required for an extinction test to be accurate?
requires that the damage has not involved the primary sensory area.
