Chapter 10 Flashcards
hierarchical organization ex
grooming in the rat (Kent Berridge & Ian Whishaw 1992)
- many levels of the nervous system participate in producing the elements and the organization of grooming behavior
- grooming behavior is produced from many levels - spinal cord to cortex
- each region adds difference to behavior
spinal cord
- center for reflexes
- can mediate many reflexes, inlcuding limb approach to attack stimulus and limp withdrawl from noxious stimulation
- stepping responses and walking
hind brain
postural support
- cranial nerves have motor nuclei in hindbrain - host efferent outgoing fibers that controlled muscles in head and neck
- sensory input also includes spinal motor system
low decerebrates
(Bazett & Penfield 1922)
- if hindbrain and spinal cord remain connected from injury, but disconnected from the rest of the brain
- difficulty maintaining consciousness
- inactive when undisturbed
- no effective ability to thermoregulate
- ability to swallow food
- affective behaviors when stimulated
- effective emotional behaviors shown
- slow-wave sleep and active sleep
- sudden collapse accompanied by loss of all body tone that lasts from 15 sec - 12 min → active REM sleep
high decerebrates
(Bard & Macht 1958, Bignall & Schramm 1974)
disconnected diencephalon from the midbrain regions
intact olfactory, hypothalamus, pituitary
- respond to simple visual and auditory stimulation
- automatic behaviors
- voluntary movements
- hormonal system and homeostasis
midbrain
- all of the subsets of voluntary movements
- bc they are executed through lower level postural support and reflex systems, voluntary movement can also be elicited by lower level sensory input bc they are executed through lower level postural support and reflex systems
- integrated with lower-level sensory inputs by both ascending and descending connections
- effective automatic movements
- ascending and descending connections
mesencephalic child
Brachville 1971
- had no brain above the diencephalon
- response did not change in magnitude and did not habituated, gradually decrease in intensity, to repeated presentations
- so they concluded that the forebrain is not important in producing movements but is important in not generating and inhibiting them
diencephalon
- affect and motivation
- energizes and sustains behavior
sham rage/quasi emotional phenomenon
(Canon & Britain, 1924)
- displays sympathetic nervous system signs of rage
- to occur, the posterior part of the hypothalamus must be intact
- suggest that the diencephalon energizes an animal’s behavior
decorticated animals
removal of neocortex
- typical sleeping-waking cycles
- ability to sequence series of movements
- ability to generate biologically adaptive behaviors by inhibiting
- ex: decorticated animal walks until it finds food or water, and then inhibits walking to consume the food or water -> the basal ganglia probably provides the circuitry required for the stimulus to inhibit movement so that ingestion can occur
- do not build nests, some nest building behaviors
- do not hoard food, but might carry food around
- difficulty making skilled movements w tongue and limbs because cannot protrude the tongue or extend one limb
- Oakley 1979: decorticated animals perform well in tests of classical conditioning, operant conditioning, approached learning, cue learning, pattern discrimination
- cortex is not essential for learning itself
- fail at learning complex pattern discernations and how to find their way around a space
modular organization Zeki 1993
- cortical module might be performing same basic function throughout cortex
- most interaction between the cortical layers take place vertically within the neurons, directly above or below adjacent layers
- vertical bias —> basis for 2nd type of neocortical organizations —> columns or modules
- evidence comes from standing and probing methodologies
- physiological way evidence
- If microelectrode is placed in the somatosensory cortex and lowered vertically from layer one to layer five for ex, all the neurons encountered appear functionally similar, the functional similarity of cells across all six layers at any point in the cortex.
modular organization Pauves et al 1992
- some modular patterns in the cortex may correspond to secondary functions of cortical organization
- one possibility is that cortical modules may be an incidental consequence of synoptic processing in the cortex
vertical modules
efficient pattern of connectivity
- nerve cells easily distinguished in the cortex has spiny neurons or aspiny neurons by the presence or absence respectively of dendritic spines
spiny neurons
- excitatory
- 95% of excitatory synapses are found on the spines
- likely to have receptors for the excitatory transmitter glutamate or aspartate
- ex: pyramid cells
pyramid cells
spiny neurons
- send info from a cortical region to another cortical region of the central nervous system
- efferent projection neurons of the cortex
- largest population of cortical neurons
- found in layer 2,3,5,6
spiny stellate cells
smaller stars shaped interneurons whose processes remain within the region of the brain, where the cell body is located
aspiny neurons
- interneurons with short axons and non dendritic spines
- inhibitory
- likely use gamma aminobutyric acid GABA as neurotransmitter
neocortex layers
4-6 layers with different functions, different afferents, and different efferent axons
- thickness corresponds to function
- somatosensory cortex has a relatively large layer 4 and smaller 5
- motor cortex has relatively large layer 5 and smaller layer 4
- various cortical layers can be distinguished by the neuronal elements that each one contain
neocortex layer 4
- input zone of sensory analysis
- receive projections from other cortical areas and other areas of the brain
neocortex layer 5-6
- output zone
- send axons to other cortical areas or other brain areas
mapping reality
Penfield 1950s
- stimulated their patient’s motor and somatosensory strips - identified two regions of parietal cortex that appeared to represent localized body parts (like leg and face)
- dozens of maps in each sensory modality
- multimodal cortex presumably function to combine characteristics of stimuli across different sensory modality
multimodal cortex
Ghazanfar 2005
- the convergence of qualitatively different sensory info alters our perception of the world
- areas that have more than one sensory modality
- When monkeys listened to a recording of another monkey’s voice, the auditory neurons’ firing rate increased by about 25% if the voice was accompanied by a visual image of a monkey cooing, but only if the voice and facial movements were in synchrony
- shows that we have parallel cortical systems
- one system allows us to understand the world and the other to move us around and manipulate it
Jerison 1991
our knowledge of reality is directly related to the structure and number of our cortical maps
primary sensory cortex
cortical system
- primary sensory cortex - projects to interconnected sensory association regions
- these regions project to several cortical targets
- these targets can be the frontal lobe, the paralimbic cortex, the multimodal cortex, and the subcortical connections and loops
frontal lobe
primary motor cortex
- motor homunculous
- most sensory region fibers connect directly to primary motor cortex
- and may project either to the premotor or prefrontal cortices
premotor cortex
(frontal lobe)
- ordering movements in time
- controlling hand, limb, or eye movements with respect to specific sensory stimuli
prefrontal cortex
(frontal lobe)
- controlling movements in time
- forming short term memories of sensory info
paralimbic cortex
- forming long term memories
- comprised of three layers adjacent and directly connected to the limbic structures of paralimbic cortex
- can be seen in two places:
- medial surface of temporal lobe
* perirhinal cortex, entorhinal cortex, and parahippocampal cortex
- medial surface of temporal lobe
- just above corpus callosum where it is referred to as the cingulate cortex
neocortex
- recieves all sensory input through subcortical structures
- either directly from the thalamus
- or indirectly through midbrain structures such as the tectum
subcortical loops
- each level interacts and is integrated with higher and lower levels by ascending and descending connections
- connect the cortex, thalamus, amygdala, and hippocampus
- indirect loop with the striatum connects with the thalamus
- plays some role in amplifying or modulating ongoing cortical activity
binding problem
How does sensation in specific channels, whether touch, vision, hearing, smell, and taste combine into perceptions that translate as a unified experience that we call reality? → how the brain ties single and varied sensory and motor events together into a unified perception on behavior that will bring us to another point
serial hierarchical model
Luria 1973
- anatomical criteria can help in delineating a hierarchical organization of cortical areas
- sensory unit: posterior cortex, parietal, occipital, temporal lobe
- motor unit: anterior cortex, frontal lobe
- zonal pathways
- sensory input enters primary sensory zone is elaborated in the secondary zone and is integrated in the tertiary zones of the posterior unit
- to execute an action, activation is sent from the posterior tertiary sensory zones to the tertiary frontal motor zone for formulation, to the secondary motor zone for elaboration and then to the primary frontal zone for execution
zonal pathways
perceived that the cortical units worked in concert along zonal pathways
serial hierarchical model assumptions
- the brain processes information serially
- serial processing is hierarchical
- our perception of the world is unified and coherent
serial hierarchical model problems
- a strictly hierarchical processing model requires that all cortical areas be linked serially, but this serial linkage is not the case
- all cortical areas have reentrant reciprocal connections with the region to which they connect
- no simple feed forward system
- the fact that cortical operations are relayed directly to sub-cortical areas implies that cortical processing can bypass Luria’s model hierarchy and go directly to sub-cortical model structures
- we can experience a single precept despite the fact that no single terminal area is producing it
distributed hierarchical system
Felleman & Essen 1991
- cortical areas are indeed hierarchically organized in some well-defined sense
- with each area occupying a specific position relative to others, but with more than one area occupying a given hierarchical level
- human connectome project: ambition venture aimed at shorting human brain connectivity using noninvasive mirror imaging in a population of 1200 healthy adults
- based on the observation that a living brain is always active by studying resting state fMRIs
the ability of our brains to be changed by experience and to recover from damage is due to the quality known as
plasticity
an animal in which only the hindbrain and spinal cord remain is said to be
low decerebrate
a person in a persistent vegetative state most resembles an animal with experimental lesions to the
hindbrain
all aspiny neurons are thought to release ___ as on of their neurotransmitters
GABA
areas that function to combine characteristics of stimuli across different sensory modalities are called
polymodal
what does the binding problem ask?
how to sensations in specific channels combine into perceptions that translate as a unified experience that we call reality?
___ are reciprocal feedback loops that play some role in amplifying or modulating cortical activity
subcortical loops
the paralimbic cortex is primarily concerned with
memory formation
postural support
- sensory input also includes spinal motor system
hind brain
(Bazett & Penfield 1922)
- if hindbrain and spinal cord remain connected from injury, but disconnected from the rest of the brain
low decerebrates
(Bard & Macht 1958, Bignall & Schramm 1974)
disconnected diencephalon from the midbrain regions
intact olfactory, hypothalamus, pituitary
high decerebrates
- all of the subsets of voluntary movements
- bc they are executed through lower level postural support and reflex systems, voluntary movement can also be elicited by lower level sensory input bc they are executed through lower level postural support and reflex systems
- integrated with lower-level sensory inputs by both ascending and descending connections
- effective automatic movements
- ascending and descending connections
midbrain
Brachville 1971
- had no brain above the diencephalon
- response did not change in magnitude and did not habituated, gradually decrease in intensity, to repeated presentations
- so they concluded that the forebrain is not important in producing movements but is important in not generating and inhibiting them
mesencephalic child
(Canon & Britain, 1924)
- displays sympathetic nervous system signs of rage
- to occur, the posterior part of the hypothalamus must be intact
- suggest that the diencephalon energizes an animal’s behavior
sham rage/quasi emotional phenomenon
removal of neocortex
decorticated animals
- cortical module might be performing same basic function throughout cortex
- evolutionary expansion of the cortex corresponds to increase in the number of basic units
- most interaction between the cortical layers take place vertically within the neurons, directly above or below adjacent layers
- vertical bias —> basis for 2nd type of neocortical organizations —> columns or modules
- evidence comes from standing and probing methodologies
- physiological way evidence
- If micro electrode is placed in the somatosensory cortex and lowered vertically from layer one to layer five for example, all the neurons encountered appear functionally similar, the functional similarity of cells across all six layers at any point in the cortex.
modular organization Zeki 1993
- some modular patterns in the cortex may correspond to secondary functions of cortical organization
- one possibility is that cortical modules may be an incidental consequence of synoptic processing in the cortex
modular organization Pauves et al 1992
efficient pattern of connectivity
- nerve cells easily distinguished in the cortex has spiny neurons or aspiny neurons by the presence or absence respectively of dendritic spines
vertical modules
- excitatory
- 95% of excitatory synapses are found on the spines
- likely to have receptors for the excitatory transmitter glutamate or aspartate
- ex: pyramid cells
spiny neurons
- send info from a cortical region to another cortical region of the central nervous system
- efferent projection neurons of the cortex
pyramid cells
smaller stars shaped interneurons whose processes remain within the region of the brain, where the cell body is located
spiny stellate cells
- interneurons with short axons and non dendritic spines
- inhibitory
aspiny neurons
4-6 layers with different functions, different afferents, and different efferent axons
- thickness corresponds to function
- somatosensory cortex has a relatively large layer 4 and smaller 5
- motor cortex has relatively large layer 5 and smaller layer 4
- various cortical layers can be distinguished by the neuronal elements that each one contain
neocortex layers
- input zone of sensory analysis
- receive projections from other cortical areas and other areas of the brain
neocortex layer 4
- output zone
- send axons to other cortical areas or other brain areas
neocortex layer 5-6
- stimulated their patient’s motor and somatosensory strips - identified two regions of parietal cortex that appeared to represent localized body parts (like leg and face)
- dozens of maps in each sensory modality
- multimodal cortex presumably function to combine characteristics of stimuli across different sensory modality
mapping reality
Ghazanfar 2005
- the convergence of qualitatively different sensory info alters our perception of the world
- When monkeys listened to a recording of another monkey’s voice, the auditory neurons’ firing rate increased by about 25% if the voice was accompanied by a visual image of a monkey cooing, but only if the voice and facial movements were in synchrony
- shows that we have parallel cortical systems
- one system allows us to understand the world and the other to move us around and manipulate it
multimodal cortex
our knowledge of reality is directly related to the structure and number of our cortical maps
Jerison 1991
- primary sensory cortex - projects to interconnected sensory association regions
- these regions project to several cortical targets
- these targets can be the frontal lobe, the paralimbic cortex, the multimodal cortex, and the subcortical connections and loops
primary sensory cortex
cortical system
- motor homunculous
- most sensory region fibers connect directly to primary motor cortex
- and may project either to the premotor or prefrontal cortices
primary motor cortex
(frontal lobe)
- ordering movements in time
- controlling hand, limb, or eye movements with respect to specific sensory stimuli
premotor cortex
(frontal lobe)
- controlling movements in time
- forming short term memories of sensory info
prefrontal cortex
forming long term memories
paralimbic cortex
- recieves all sensory input through subcortical structures
- either directly from the thalamus
- or indirectly through midbrain structures such as the tectum
neocortex
- each level interacts and is integrated with higher and lower levels by ascending and descending connections
- connect the cortex, thalamus, amygdala, and hippocampus
- indirect loop with the striatum connects with the thalamus
- plays some role in amplifying or modulating ongoing cortical activity
subcortical loops
How does sensation in specific channels, whether touch, vision, hearing, smell, and taste combine into perceptions that translate as a unified experience that we call reality? → how the brain ties single and varied sensory and motor events together into a unified perception on behavior that will bring us to another point
binding problem
Luria 1973
- anatomical criteria can help in delineating a hierarchical organization of cortical areas
- sensory unit: posterior cortex, parietal, occipital, temporal lobe
- motor unit: anterior cortex, frontal lobe
- zonal pathways
- sensory input enters primary sensory zone is elaborated in the secondary zone and is integrated in the tertiary zones of the posterior unit
- to execute an action, activation is sent from the posterior tertiary sensory zones to the tertiary frontal motor zone for formulation, to the secondary motor zone for elaboration and then to the primary frontal zone for execution
serial hierarchical model
perceived that the cortical units worked in concert along zonal pathways
zonal pathways
- a strictly hierarchical processing model requires that all cortical areas be linked serially, but this serial linkage is not the case
- all cortical areas have reentrant reciprocal connections with the region to which they connect
- no simple feed forward system
- the fact that cortical operations are relayed directly to sub-cortical areas implies that cortical processing can bypass Luria’s model hierarchy and go directly to sub-cortical model structures
- we can experience a single precept despite the fact that no single terminal area is producing it
serial hierarchical model problems
Felleman & Essen 1991
- cortical areas are indeed hierarchically organized in some well-defined sense
- with each area occupying a specific position relative to others, but with more than one area occupying a given hierarchical level
- human connectome project: ambition venture aimed at shorting human brain connectivity using noninvasive mirror imaging in a population of 1200 healthy adults
- based on the observation that a living brain is always active by studying resting state fMRIs
distributed hierarchical system
cerebellum
coordinated motor control
central sulcus
midline to lateral fissure
- separates frontal lobe from parietal lobe
- front of it: voluntary movement, motor cortex
- behind it: sensation, sensory cortex
- broca’s area: anterior to central sulcus and on the left
frontal lobe
planning, motor execution, execution of judgement and actions
parietal lobe
somatic sensation from face and body
occipital lobe
visual information processing and recognition
temporal lobe
auditory information & new memories
lateral fissure
in superior temporal gyrus
hippocampus
(temporal lobe)
formation of new memories
corpus callosum
large bundle of fibers that hold two hemispheres together
cerebral cortex
special gray matter at the outer layer of the brain
coordinated motor control
cerebellum
midline to lateral fissure
- separates frontal lobe from parietal lobe
- front of it: voluntary movement, motor cortex
- behind it: sensation, sensory cortex
- broca’s area: anterior to central sulcus and on the left
central sulcus
planning, motor execution, execution of judgement and actions
frontal lobe
somatic sensation from face and body
parietal lobe
visual information processing and recognition
occipital lobe
auditory information & new memories
temporal lobe
in superior temporal gyrus
lateral fissure
(temporal lobe)
formation of new memories
hippocampus
large bundle of fibers that hold two hemispheres together
corpus callosum
special gray matter at the outer layer of the brain
cerebral cortex
affect and motivation
diencephalon
diencephalon disconnected from midbrain
high decerebration
diencephalic
- without the basal ganglia and cerebral hemispheres
- intact olfactory system, hypothalamus, and pituitary
- ability to control hormonal systems and maintain homeostasis
- sham rage/quasi emotional phenomenon (Canon & Britain, 1924)
- displays sympathetic nervous system signs of rage
- to occur, the posterior part of the hypothalamus must be intact
- suggest that the diencephalon energizes an animal’s behavior
- hyperactivity and energized behavior
- without the basal ganglia and cerebral hemispheres
- intact olfactory system, hypothalamus, and pituitary
diencephalic
paralimbic cortex
- difficulty maintaining consciousness
- inactive when undisturbed
- no effective ability to thermoregulate
- ability to swallow food
- affective behaviors when stimulated
- effective emotional behaviors shown
- slow-wave sleep and active sleep
- sudden collapse accompanied by loss of all body tone that lasts from 15 sec - 12 min → active REM sleep
low decerebrates
- typical sleeping-waking cycles
- ability to sequence series of movements
- ability to generate biologically adaptive behaviors by inhibiting
- ex: decorticated animal walks until it finds food or water, and then inhibits walking to consume the food or water -> the basal ganglia probably provides the circuitry required for the stimulus to inhibit movement so that ingestion can occur
- do not build nests, some nest building behaviors
- do not hoard food, but might carry food around
- difficulty making skilled movements w tongue and limbs because cannot protrude the tongue or extend one limb
decorticated animals
(Bard & Macht 1958, Bignall & Schramm 1974)
- respond to simple visual and auditory stimulation
- automatic behaviors
- voluntary movements
- hormonal system and homeostasis
high decerebrates
- ability to control hormonal systems and maintain homeostasis
- sham rage/quasi emotional phenomenon
- hyperactivity and energized behavior
diencephalic
