L&M Flashcards
Epilepsy: What happens in neurons?
Glutamate (excitatory neurotransmitter) and GABA (inhibitory neurotransmitter) are in trade-off all the time. In seizure, lack of GABA leads to overwhelming excitation.
What is epilepsy?
Sudden excitation in groups of neurons with loss of inhibitory potential
(All neurons fire at same time; brain can’t process it)
What is TLE?
Sudden, unprovoked seizures emerging from medial or lateral temporal lobe. Can be simple partial or complex partial
Cause of TLE
Most common hippocampal sclerosis - loss of neurons, growth of glial cells
What is declarative memory
Conscious access to previously learned information. Memory that can be articulated
What is procedural memory?
‘How to’ memory (eg riding a bike)
HM’s memory loss?
Lack of declarative memory; anterograde amnesia; procedural memory intact (can learn new skills, can’t remember having learnt them)
Are medial temporal lobes more important for anterograde or retrograde; declarative or procedural memories?
Anterograde and declarative
What is result of left MTL lesion?
Verbal episodic memory impairment
What is result of right MTL lesion?
Visual / spatial memory impairment
What role do temporal lobes play in memory?
Engine room of memory
What are the pathways memory takes?
Sensory input (unimodal and polymodal associations) from FTP (frontal, temporal, parietal); info into (or out of) perirhinal and para hippocampal cortices; into (or out of) entorhinal cortex, into (or out of) hippocampus (process goes both ways)
What is role of hippocampus?
In association w surrounding structures, hippocampus essential for learning and consolidating. Two views: retrieval can happen independent of hippocampus (squire - consolidation theory); retrieval dependent on hippocampus (Moscovitch - multiple trace theory)
What are relational memory tasks?
Association of two things: eg table as word and table as object. Hippocampus essential.
What are the 3 extra temporal zones related to processing of memory?
Papez’s circuit
Diencephalon
Frontal lobes
What is Papez’s circuit responsible for?
Amygdala + Papez’s circuit = limbic region (emotional expression and experience)
Declarative memory
What does Papez’s circuit comprise of?
Mammillary bodies, anterior thalamic nuclei, fornix, cingulate gyrus, hippocampus. Circuit starts and ends with hippocampus
What do lesions in Papez’s circuit result in?
Declarative and relational memory impairment
What role do frontal lobes play in memory?
Motor programming (posterior of frontal lobe - just before central sulcus) Problem solving and higher level cognitive functioning (anterior of frontal lobe [pre-frontal cortex]). This separates us from all other animals
Where are strategies developed and implemented for storing and retrieving memories?
Frontal lobes
What do lesions in frontal lobe result in?
Lack of context for memories (eg don’t remember source for memory/information), confabulation and distortion of memories,
What is the diencephalon?
Thalamus and hypothalamus
What does damage to dorso-medial nuclei in thalamus result in?
deficit in selecting appropriate information
What does damage to intralaminar/midline nuclei of thalamus do?
Damage to semantic memory and memory retrieval (reduced mental flexibility)
What is synaptic plasticity?
Where learning occurs because biochemistry of synapses has changed, altering effect on post-synaptic neuron
What is long-term potentiation?
Long term increase in excitability of neuron due to particular synaptic input caused by repeated high frequency activity of that input.
What is Hebb’s rule?
Strengthening of a synapse that is repeatedly active when the post-synaptic cell fires
What is glutamate?
Excitatory neurotransmitter