m8ta
use https for features.
text: sort by
tags: modified
type: chronology
{208}
hide / / print
ref: -2012 tags: cortex striatum learning carmena costa basal ganglia date: 09-13-2019 18:30 gmt revision:6 [5] [4] [3] [2] [1] [0] [head]

PMID-22388818 Corticostriatal plasticity is necessary for learning intentional neuroprosthetic skills.

  • Trained a mouse to control an auditory cursor, as in Kipke's task {99}. Did not cite that paper, claimed it was 'novel'. oops.
  • Summed neuronal firing rate of groups of 2 or 4 M1 neurons.
  • Auditory feedback was essential for the operant learning.
    • One group increased the frequency with increased firing rate; the other decreased tone with increasing FR.
  • Specific deletion of striatal NMDA receptors impairs the ability to learn neuroprosthetic skills.
    • Hence, they argue, cortico-striatal plastciity is required to learn abstract skills, such as this tone to firing rate target acquisition task.
  • Controlled by recording EMG of the vibrissae + injection of lidocane into the whisker pad.
  • One reward was sucrose solution; the other was a food pellet. When the rat was satiated on one modality, they showed increased preference for the opposite reward during BMI control -- thereby demonstrating intentionality. Clever!.
  • Noticed pronounced oscillatory spike coupling, the coherence of which was increased in low-frequency bands in late learning relative to early learning (figure 3).
  • Genetic manipulations: knockin line that expresses Cre recombinase in both striatonigral and striatopallidal medium spiny neurons, crossed with mice carrying a floxed allele of the NMDAR1 gene.
    • These animals are relatively normal, and can learn to perform rapid sequential movements, but are unable to learn precise motor sequences.
    • Acute pharmacological blockade of NMDAR did not affect performance of the neuroprosthetic skill.
    • Hence the deficits in the transgenic mice are due to an inability to perform the skill.

{241}
hide / / print
ref: Costa-2006.1 tags: Rui Costa Miguel Nicolelis Dopamine depletion excess cortex striatum hyperkinesia akinesia parkinsons DAT-KO date: 03-02-2012 01:03 gmt revision:8 [7] [6] [5] [4] [3] [2] [head]

PMID-17046697 Rapid alterations in corticostriatal ensemble coordination during acute dopamine-dependent motor dysfunction.

  • used rats where they could rapidly switch between dopamine depletion (0.2%) and overexpression (500%)
  • most cortical and striatal neurons ( approximately 70%) changed firing rate during the transition between dopamine-related hyperkinesia and akinesia,
    • buuut the overall cortical firing rate remained unchanged
  • repeated dopamine depletion is accompanied by the loss of glutamergic synapses in striatopallidal neurons (Day et al 2006) PMID-16415865 (Kaneda et al 2005). PMID-16367790
  • with Marc Caron
  • Dopamine is believed to modulate positively the direct striatal pathway that contains predominantly D1-type receptors and disinhibits cortical neurons to modulate negatively the indirect pathway that predominantly contains D2-type receptors and increased crotical inhibition (Albin et al 1989 {1050}, Filion and Tremblay 1991; Gerfen 1992, Parr-Brownlie and Hyland, 2005).
  • According to the classical view (Albin et al 1989), lack of DA release should lead to inhibition of cortical activity and an inability to produce movement, while an excess of Dopamine should lead to increased cortical activity and hyperactivity (Gerfen, 1992).
    • mouse model: DDD PMID-17030735[] (dopamine transporter knockout)

{689}
hide / / print
ref: HilArio-2007.01 tags: Rui Costa endocannabinoid habit reward striatum basal ganglia date: 03-05-2009 19:04 gmt revision:0 [head]

PMID-18958234 Endocannabinoid Signaling is Critical for Habit Formation.

  • quick review (the intro is packed with grat information):
    • in goal-directed learning, behavior is highly sensitive to the incentive value of the outcome, and contingency between the action and the outcome.
    • with repetition actions become both more efficient and more automatic.
    • after extensive training, rats move from goal-directed behavior to more habitual response independent of outcome value.
      • random interval schedules favor this more than random ratio reward schedules.
        • in mice, random interval schedules promoted habit formation, whereas random ratio schedules promoted acquisition of goal-directed behaviors. does this also apply to humans? I would guess so. Might be an interesting tool to have in the toolbox.
        • interval schedules promoted the exploration of a random lever whereas ratio schedules promoted the exploitation of the reward lever.
    • the underlying circuitry supporting goal-directed behav and habit formation are different:
      • goal directed behavior seems to require the associative BG/cortex including:
        • dorsomedial or associative striatum (medial!)
          • COMT, a transporter, is more highly expressed here than DAT.
        • pre-limbic ctx
        • mediodorsal thalamus
      • habit formation requries:
        • dorsolateral or sensorimotor striatum (lateral!)
          • DAT, dopamine transporter, is highly expressed here.
        • infralimbic cortex
    • amphetamine sensitization can lead to increased spine density in medium spiny neurons in the dorsolateral striatum, while decreasing spine density in the dorsomedial striatum. (interesting!)
    • lesions of nigrostriatal input to dorsolateral striatum impairs habit formation;
    • infusion of dopamine into the ventral medial prefrontal cortex favors goal-directed behavior
      • that is a rather broad statement to make ...
  • endocannabinoid release in the striatum is required for LTD induction.
  • endocannabinoid signaling regulated bt DA.
  • CB1 (the receptor implicated in addiction) is highly expressed in the dorsolateral striatum (habit!) at both excitatory and inhibitory terminals.
  • used mice with CB1 mutations therefore!
  • CB1 mutant mice have impaired habit formation and enhanced exploration.
    • suggest that endocannabinoid signaling is critical for both habit formation and increased exploration in interval schedules.