PSYC 311

what did Penfield discover in his stimulations

the somatotopic organization of the gyri homunculus.

What are the characteristics of the gyri homunculus

inverted map of body, disproportionatebody representation based on sensory input, contralateral control

How is the medial temporal lobe divided?

Parahippocampal gyrus, fusiform gyrus, ITG (inferior temporal gyrus)

How many layers does the limbic cortex have

3 or 4

What are the sulci of the medial surface

cigulate sulcus, cingulate gyrus, CC

pyramidal neurons

soma is shaped like a pyramid. Basal dendrites, apical dendrites, and long axons. these are the typical cortical neuron

granule/stellate neurons

much smaller, rounder cells. axons usually do not leave the, mainly distribute info to the other layers

How can we look at cell body

Nissl stain

What is the study of the cytoarchitecture of the cortex

the study of how these cells vary in size and density

cytoarchitecture of primary sensory areas

receive lots of direct input from specific nuclei of the thalamus and have a very large layer 4

which areas are hypergranular

primary sensory areas (koniocortex)

what is the cytoarchitecture of the motor cortex

agranular (lacks cells in layer 4)

why is the motor cortex agranular

because it needs to send info subcortically

What are the characteristics of the primary motor cortex

Betz cells, in layer 5 of BA4 extremely large pyramidal neurons whose axons project directly to spinal cord

• larger in dorsal primary cortex *BA4 is hidden within the anterior bank of the central sulcus, except at dorsal end

Where is S1

Post central gyrus

What are the three distinct areas of the PCG

BA3 (posterior bank of central sulcus) BA1 and BA2

Why is BA3 distinct

it has the largest layer 4 and is the first cortical area to receive input from the thalamus

What is the transverse gyrus within the temporal lobe

the Hesschl gyrus

Where is the primary auditory cortex (and area)

A1/BA41, sits on Hesschl gyrus

Cortico-cortical connections axons

primarily axons from layer 3 pyramidal cells.

Association fibers

cortico-cortical connections within the same hemisphere

commissural fibers

cortico-cortical connections between hemispheres

Cortico-subcortical connections

projection fibers

rostrum of the CC

connects the orbito-frontal cortex

genu of CC

Connects the frontal lobes

Body of CC function

Connects the motor and somatosensory areas

Splenium of CC

connects the posterior parietal and occipital lobes

What does Mohr propose for reason of Broca's aphasia

caused by blockage of the upper division of the left middle cerebral artery

what does Mohr propose happens when there is damage to broca's area alone

a mild language deficit

Where did Broca report damage

in the left posterior inferior gyrus but there was also damage in the insula, the claustrum, the putamen, the inferior parietal lobule

What did Dronkers discover

damage in insula results in speech apraxia

according to Dronkers, what is the anterior insula responsible for?

motor control

according to Dronkers, what is the posterior insula responsible for?

Somatosensory control

what are area 4 and 6 responsible for

motor control of orofacial musculature

area 44

higher level motor control of utterrances, probably works with anterior insula to regulate motor control for speech

area 45

a higher cognitive area involved in active memory retrieval. In left hemi, probably necessary for retrieving info that is to be communicated

Wada test

usage of sodium amytal test. Researchers would inject into the left or right internal carotid and monkeys are temporarily paralyzed on the opposite side of the body. Suggested this could be used on patients to determine lateralization of language. Inject into the left internal carotid artery and left hemisphere will temporarily shut down. patient raises both arms and names words. the right arm will fall and the patient will stop talking

what did HM have trouble with?

memory consolidation. short term to long term.

what happens when there is unilateral MTL damage on the left?

verbal memory impairment

what happens when there is unilateral MTL damage on the right?

nonverbal memory impairment (abstract designs, spatial tasks, music)

What did Corsi find with patients with unilateral damage to left limbic MTL

The number of repetitions needed to learn the sequence correlated with the amount of damage. The more posterior the damage went, the bigger the impairment

What did Corsi find with patients with unilateral damage to right limbic MTL

tapping sequence. Results similar, the more posterior the damage went, the more trials needed.

what is a visual discrimination task

works through extinction, not punishment. response to B never gets rewarded, A does. Procedural memory

what makes up procedural memory

unidirectional connections. Cortico-striatal and cortico-basal ganglia connections. Striatum-caudate nucleus, putamen, GP

What is parallel processing

you can have two independent types of learning about the same objects: memory with awareness and procedural memory

what does the inferior temporal gyrus compute

visual processing

how does visual processing work?

the image of the stimulus goes into the medial temporal lobes to be able to remember the object and also to the basal ganglia to remember how to interact with the object

What happens when there is lesions to pathway 1 (medial temporal lobes)

monkeys cannot perform the DNMS, can perform VD tasks

What happens when there is lesions to pathway 2 (basal ganglia)

can't preform VD tasks, can perform DNMS

apraxia

a problme with action but not due to paralysis or a lack of comprehension

ideomotor apraxia

failure to coordinate the muscles to create an action for communication

patients with ideomotor apraxia have what kind of damage?

damage to the left supramarginal gyrus and underlying white matter

Geschwind's interpretation of ideomotor apraxia

ideomotor apraxia is a disconnection syndrome. the problem lies in going from understanding the command to carrying out the action. importance of the left arcuate fasciculus. verbal command is heard via auditory cortex (Heschl's gyrus), command understood in Wernickes area, command is sent to motor association cortex (BA6) via arcuate fasciculus, then sent to primary motor cortex (area 4) to carry out command directly with muscles

what will happen if there is damage to left arcuate fasciculus

means that the patient can understand the command and move normally but cannot perform the command with either side of the body

sympathetic apraxia

ideomotor apraxia with just one side of the body. some patients have a right hemiplegia and an ideomotor apraxia of the left side of the body. Often have brocas aphasia or at least some speech problems. Damage to left premotor and motor areas. Geschwind hypothesized that the command is hear and understood by the left hemisphere but cannot get to teh right motor cortex because of damage to the left motor areas

Which areas did Brodmann identify on the PCG

area 3, 1, 2

Area 3

the real S1 neurons have small receptive fields and respond to tactile stimulation of contralateral side of body

area 1

receptive fields are bigger, neurons seem to code vibrations of tactile stimulation

area 2

receptive fields are even bigger, neurons seem to change in joint poisition

where is information from the SS cortex sent

to the anterior SPL and IPL

what do neurons in the anterior SPL and IPL respond to

not tactile stimulation, but sepcific body movements. there is an integration of info about the body so that neurons code specific body movements and postures

mirror neurons

found in anterior area 6. respond when a monkey carries out an action and also when the monkey sees someone else do the same action. also found in the SMG

what happens to patients with damage to parietal lobes

they lose their body schema

what do the parietal lobes do

they integrate SS info from the post central gyrus and visual info from the OCC lobes to code for movement of the body in space and allow us to interact with our environment.

ideational apraxia

the programming of a sequence of actions to coordinate the use of various objects to execute a complex act. patient understood the command, could name objects, but could not perform the task.

ideational apraxia due to damage where?

large lesions in the left parietal lobe. can often co-occur with ideomotor apraxia

constructional apraxia

an inability to reconstruct or create 2D or 3D models. Occurs more frequently with damage in the right parietal lobe

spatial neglect

damage in the right parietal lobe, patients ignore the left side of the visual field and often the left side of their bodies

What happens to patients with damage in the left SMG?

ideomotor apraxia, conduction aphasia, agraphia

angular gyrus

reading and writing. important for linguistic interpretation. angular gyrus important for interpreting the linguistic meaning of visual input

what are the posterior parietal occipital temporal regions of the brain important for?

the extraction and interpretation of information in the world. Through interactions with the medial temporal lobe areas (amygdala, entorhinal, etc) we are able to store and create permanent knowledge.

what cortex is on the precentral gyrus

motor cortex

what are the regions in front of the central sulcus on the PCG for?

planning and organizing movements

frontal granular cortex

large part of the cortex that has layer 4 re-emerging with small granular neurons. The cortex that lies in front of the frontal agranular cortex is the motor areas and anterior to it you have the frontal granular cortex. ALSO KNOWN AS PFC

What did Hebb find in the PFC in regards to intelligence?

patients with brain tumours and other kinds of abnormalities in the anterior part of the frontal lobe have no difference in intelligence with people with damage at the PFC. Intelligence, measured by IQ tests are not affected by the prefrontal lesions.

convergent thinking

specific relationship that you have to figure out in order to give the precise answer. IQ tests.

divergent intelligence

refers tot eh types of problem-solving that does NOT have a clear answer. situations in which you require creativity, open-mindedness and cognitive flexibility.

In terms of memory, what is the hippocampus important for?

consolidation to long-term memory

Mishkin: what happens when there are lesions to just EC?

Failure to do DNMS task

What is the entorhinal cortex important for?

important for processing familiarity of stimuli that are first processed by neocortex

Where does info from the EC go?

First to the amygdala (for affective component) and hippocampus (context information)

left hippocampus

involved in semantic of linguistic context (remembering the name of someone when you see his or her face)

What is the amygdala important for in memory

Memories associated with a certain stimulus

In the animal studies, what did the EC contribute to in terms of memory consolidation?

familiarity

What happens to the information from EC after it is sent to the amygdala and hippocampus?

Back to the neocortex to be stored

What happens if you don't have an EC

neocortex functions normally (perfect perceptions, comprehension) and the info can be held within working memory but CANNOT be familiarized.

Where does visual information start?

V1 in the occipital lobe

ventral pathway

extracts the spatial relationship about objects (where)

dorsal stream

extract the patterns or features of an object (what)

Where is the perception of an object done?

in posterior infero-temporal cortex

What is area TE important for?

responsible for recognition of an object based on visual input

What happens when you have bilateral TE lesions?

No activation of the concept of the object based on visual input

Apperceptive agnosia

patient doesn't appear to be blind but perception is not perfect. Cannot draw objects when they see them, cannot match objects. Often complain of a loss of fine detail.

What causes apperceptive agnosia?

probably due to bilateral damage of equivalent of monkey area TEO (temporal occipital junction). Can also include parieto-occipital junction where patients have some problems with spatial perception

What is area TEO

temporal occipital junction

associative agnosia

patient can produce elegant drawings when viewing the object and can match objects. Cannot recognize the object based on visual input alone, no trigger of teh concept.

what causes associative agnosia?

probably due to bilateral damage of equivalent of monkey area TE

what is area TE

anterior inferiotemporal cortex

prosopagnosia

problem with recognizing faces, learn to use hair,voice, etc as cue for recognition.

what causes prosopagnosia

bilateral damage to fusiform gyrus