The effects of reversible inactivation of the red nucleus on learning-related and auditory-evoked unit activity in the pontine nuclei of classically conditioned rabbits.

Cartford, M. Claire; Gohl, E B; Singson, M; Lavond, David G.

doi:10.1101/lm.3.6.519

Cited by 33 publications

(29 citation statements)

References 37 publications

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“…However, studies in adult rabbits found that cooling the cerebellum or red nucleus did not reduce baseline activity in the pontine nuclei (Cartford et al 1997;Clark et al 1997). It is possible that the previous studies did not record from exactly the same population of neurons examined in the present study because they selected pontine units that showed conditioning-related activity.…”

Section: Discussioncontrasting

confidence: 41%

“…One of the previous studies also found that cooling the red nucleus reduced stimulus evoked activity in the pontine nuclei (Cartford et al 1997). The developmental change in the magnitude of short latency evoked activity (phasic activity) in the pontine nuclei could therefore be related to a developmental change in the efficacy of the projection from the red nucleus to the pontine nuclei.…”

Section: Discussionmentioning

confidence: 96%

“…In adult rabbits, inactivation of the interpositus nucleus or the red nucleus blocks excitatory feedback to the pontine nuclei, abolishing increases in neuronal activity at the end of the CS period (Cartford et al 1997;Clark et al 1997;Bao et al 2000). Excitatory feedback might be more effectively driving pontine activity during the CS in the sustained and late response units in the older rats.…”

Section: Discussionmentioning

confidence: 99%

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Developmental Changes in Eyeblink Conditioning and Neuronal Activity in the Pontine Nuclei

Freeman¹,

Muckler²

2003

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Neuronal activity was recorded in the pontine nuclei of developing rats during eyeblink conditioning on postnatal days 17-18 (P17-P18) or P24-P25. A pretraining session consisted of unpaired presentations of a 300-msec tone conditioned stimulus (CS) and a 10-msec periorbital shock unconditioned stimulus (US). Five paired training sessions followed the unpaired session, consisting of 100 trials of the CS paired with the US. The rats trained on P24-P25 exhibited significantly more conditioned responses (CRs) than the rats trained on P17-P18, although both groups produced CRs by the end of training. Ontogenetic increases in pre-CS and stimulus-elicited activity in the pontine nuclei were observed during the pretraining session and after paired training. The activity of pontine units was greater on trials with CRs relative to trials without CRs in rats trained on P24-P25, but almost no CR-related modulation was observed in the pontine units of rats trained on P17-P18. The findings indicate that pontine neuronal responses to the CS and modulation of pontine activity by the cerebellum and red nucleus undergo substantial postnatal maturation. The developmental changes in pontine neuronal activity might play a significant role in the ontogeny of eyeblink conditioning.

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Section: Discussioncontrasting

confidence: 41%

Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 99%

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Developmental Changes in Eyeblink Conditioning and Neuronal Activity in the Pontine Nuclei

Freeman¹,

Muckler²

2003

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“…The developmental change in pontine neuronal activity during an acoustic CS is probably not related to maturation of the peripheral auditory system or cochlear nuclei, because behavioral and auditory brainstem response studies indicate that basic auditory function is evident by P15 or P16 in rats (Hyson andRudy 1984, 1987;Blatchley et al 1987;Sananes et al 1988;Stanton et al 1992). However, we do not know whether the developmental change in pontine responsiveness to acoustic stimuli is due to developmental changes in the projection of the cochlear nuclei to the pons, intrinsic properties of pontine neurons, or feedback projections from the cerebellum and red nucleus (Cartford et al 1997;Clark et al 1997). It is also possible that there are developmental changes in the mossy fiber projection to the cerebellum including myelination and increased synaptic efficacy.…”

Section: Discussionmentioning

confidence: 94%

Pontine stimulation overcomes developmental limitations in the neural mechanisms of eyeblink conditioning

2005

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Pontine neuronal activation during auditory stimuli increases ontogenetically between postnatal days (P) P17 and P24 in rats. Pontine neurons are an essential component of the conditioned stimulus (CS) pathway for eyeblink conditioning, providing mossy fiber input to the cerebellum. Here we examined whether the developmental limitation in pontine responsiveness to a CS in P17 rats could be overcome by direct stimulation of the CS pathway. Eyeblink conditioning was established in infant rats on P17-P18 and P24-P25 using pontine stimulation as a CS. There were no significant age-related differences in the rate or level of conditioning. Eyeblink conditioned responses established with the stimulation CS were abolished by inactivation of the ipsilateral cerebellar nuclei and overlying cortex in both age groups. The findings suggest that developmental changes in the CS pathway play an important role in the ontogeny of eyeblink conditioning.Eyeblink classical conditioning has been used as a model system for examining developmental changes in the neural mechanisms underlying motor learning . It is well established that eyeblink conditioning in adult mammals depends on cerebellar interactions with its afferent and efferent brainstem nuclei (Mauk and Donegan 1997;Christian and Thompson 2003). The cerebellum receives input stimulation from an auditory conditioned stimulus (CS) through the pontine mossy fiber projection (Steinmetz et al. , 1987(Steinmetz et al. , 1989Steinmetz 1990;Steinmetz and Sengelaub 1992;Tracy et al. 1998). Input stimulation from an air puff or face shock unconditioned stimulus (US) reaches the cerebellum through the climbing fiber projection from the inferior olive (McCormick et al. 1985;Mauk et al. 1986;Steinmetz et al. 1989). The convergence of mossy and climbing fiber activation of cerebellar neurons is thought to result in changes in synaptic efficacy that constitute the substrate of learning and drive the production of the eyeblink conditioned response (CR). Cerebellar output produces inhibitory feedback to the inferior olive and excitatory feedback to the pons (Sears and Steinmetz 1991;Clark et al. 1997;Kim et al. 1998;Bao et al. 2000;Medina et al. 2002). The feedback connections are thought to be important for acquisition and maintenance of CRs (Medina et al. 2002).Eyeblink conditioning emerges ontogenetically between postnatal days (P) P17 and P24 in rats (Stanton et al. 1992). Neurophysiological, neuropharmacological, and neuroanatomical analyses of the ontogeny of eyeblink conditioning in rats indicate that the developmental emergence of eyeblink conditioning is due to developmental changes in the CS and US pathways . The most substantial developmental change in the US pathway is an increase in the magnitude of cerebellar inhibitory feedback to the inferior olive (Nicholson and Freeman Jr. 2003a,b). The developmental change in inhibitory feedback is due to an increase in inhibitory synapses within the inferior olive (Nicholson and Freeman Jr. 2003a). Developmental addition of inhibitory syn...

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“…Auditory cues were previously reported to be selectively relayed to the cerebellum through the LPN (Bao, Chen, & Thompson, 2000;Steinmetz et al, 1987), while other research found auditory-evoked responses throughout both the LPN and MPN (Cartford, Gohl, Singson, & Lavond, 1997). Based on multi-unit recordings, Taub and Mintz (2010) argued that amygdala-dependent CRs enhance tone-mediated reactivity in PN neurons along most of its medial-lateral axis.…”

Section: Discussionmentioning

confidence: 99%

Central amygdala lesions inhibit pontine nuclei acoustic reactivity and retard delay eyeblink conditioning acquisition in adult rats

Pochiro

Lindquist

2015

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In delay eyeblink conditioning (EBC) a neutral conditioned stimulus (CS; tone) is repeatedly paired with a mildly aversive unconditioned stimulus (US; periorbital electrical shock). Over training, subjects learn to produce an anticipatory eyeblink conditioned response (CR) during the CS, prior to US onset. While cerebellar synaptic plasticity is necessary for successful EBC, the amygdala is proposed to enhance eyeblink CR acquisition. In the current study, adult Long-Evans rats received bilateral sham or neurotoxic lesions of the central nucleus of the amygdala (CEA) followed by 1 or 4 EBC sessions. Fear-evoked freezing behavior, CS-mediated enhancement of the unconditioned response (UR), and eyeblink CR acquisition were all impaired in the CEA lesion rats relative to sham controls. There were also significantly fewer c-Fos immunoreactive cells in the pontine nuclei (PN)-major relays of acoustic information to the cerebellum-following the first and fourth EBC session in lesion rats. In sham rats, freezing behavior decreased from session 1 to 4, commensurate with nucleus-specific reductions in amygdala Fos+ cell counts. Results suggest delay EBC proceeds through three stages: in stage one the amygdala rapidly excites diffuse fear responses and PN acoustic reactivity, facilitating cerebellar synaptic plasticity and the development of eyeblink CRs in stage two, leading, in stage three, to a diminution or stabilization of conditioned fear responding.

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The effects of reversible inactivation of the red nucleus on learning-related and auditory-evoked unit activity in the pontine nuclei of classically conditioned rabbits.

Cited by 33 publications

References 37 publications

Developmental Changes in Eyeblink Conditioning and Neuronal Activity in the Pontine Nuclei

Developmental Changes in Eyeblink Conditioning and Neuronal Activity in the Pontine Nuclei

Pontine stimulation overcomes developmental limitations in the neural mechanisms of eyeblink conditioning

Central amygdala lesions inhibit pontine nuclei acoustic reactivity and retard delay eyeblink conditioning acquisition in adult rats

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